Forehand KC and how we initiate strokes - My Chat with Claude

[MGArchitect]

Link to AI chat: https://claude.ai/share/01241d52-d53f-4127-a791-b63e695e6946

Part 1 of 3 (more at posts #33-#37)

In the tennis forehand, how is power generated? Use scientific journals and resources and not online discussion forums in exploring the answer.

This is a rich topic with strong scientific literature. Here is a thorough synthesis drawing from peer-reviewed sources — primarily Elliott's foundational British Journal of Sports Medicine paper, the Strength & Conditioning Journal review, and several PMC/journal studies.

​

---

How Power Is Generated in the Tennis Forehand

Power in the tennis forehand is not produced by a single action, but through a cascade of coordinated mechanical events. The scientific literature consistently organizes these around three interlocking mechanisms: the kinetic chain, the stretch-shortening cycle, and internal rotation of the shoulder.

​

---

1. The Kinetic Chain: Ground Up

The foundational principle of forehand power is proximal-to-distal sequencing — the transfer of energy from the ground upward through successively faster body segments.

The process begins with ground reaction forces that are channeled through the legs and hips, accelerating the pelvis. The trunk then acts as a force-transmitting and force-multiplying link, rotating explosively to accelerate the shoulder girdle. This proximal-to-distal sequencing culminates in the rapid acceleration of the arm, wrist, and racket, with each successive segment reaching a higher peak angular velocity.

Relative to intermediate players, high-performance athletes do not adopt radically different joint postures, but rather generate and transmit force more effectively along the kinetic chain — from the legs and pelvis through the trunk to the distal segments — culminating in a faster whipping action of the wrist.

Research on skill-level differences confirms that the tendency toward higher racket velocity was caused by significantly different timing patterns of maximum angular pelvis and trunk rotation rather than differences in arm mechanics alone.

​

---

2. Trunk and Hip Rotation as the Engine

The torso is where raw power is largely generated before being transmitted upward.

Vigorous axial hip and upper-trunk rotation allow for energy transfer from the lower extremity to the upper extremity in the square-stance forehand. The upper trunk tends to counter-rotate about 90–100° from parallel to the baseline and about 30° beyond the hip in the transverse plane in preparation for the stroke. Forward axial torque to rotate the hips achieves its peak at the initiation of the forward stroke.

The main kinetic chain motions that create racket speed in the forehand are trunk rotation, horizontal shoulder adduction, and internal rotation.

​

---

3. The Stretch-Shortening Cycle: Elastic Energy Storage

A critical but often underappreciated mechanism is the muscular pre-tensioning that occurs during the backswing. This is known as the stretch-shortening cycle (SSC).

In a stretch-shorten cycle, elastic energy stored during the eccentric phase of the action (the stretch) is partially recovered, such that the concentric phase (shorten) is enhanced. This is also supported by the fact that the concentric action begins with the appropriate muscles under higher tension than would be created if they were to contract purely concentrically from a resting state. Research has shown that the benefit to performance from these two factors, particularly the muscle pre-tension, is critical to success in sports such as tennis.

In the forehand specifically, rotation of the shoulders greater than the hips (creating a separation angle) and the positioning of the upper limb relative to the trunk during the backswing phase place appropriate muscles on stretch.

The trunk acts as a primary power generator, with a counter-rotation during the preparation phase storing elastic energy in the trunk muscles, which is then explosively released during the forward swing.

Timing is critical: the benefit of this stored energy is reduced if a delay occurs between these phases of the movement. In the bench press, after a period of about one second, 55% of the stored energy was lost. This is why a smooth, continuous transition from backswing to forward swing is mechanically essential.

​

---

4. Shoulder Internal Rotation: The Final Accelerator

Once energy has been transferred from the ground through the trunk and shoulder girdle, the final and decisive accelerator is internal rotation of the upper arm at the shoulder joint.

Work by Elliott's team has primarily been responsible for identifying the important role that internal rotation of the upper arm at the shoulder joint plays in the forehand strokes. Functionally, the internal rotator musculature must accelerate the upper arm in the swing to impact, before the external rotators eccentrically contract to decelerate this rotation during the follow-through phase of the action.

Forward rotation of the upper trunk coincides with a lag in the upper extremity resisted by eccentric muscle actions and large peak shoulder horizontal adductor and internal rotation torques. Well-coordinated sequential rotations up the kinetic chain through the trunk and upper extremity take advantage of the stretch-shortening cycle of muscle actions.

Research using inertial measurement units has confirmed that shoulder horizontal flexion, elbow extension, and shoulder internal rotation are major contributors to racket-head speed in attacking forehands.

​

---

5. The Role of the Wrist and Grip

The wrist and grip are not primary power generators, but they are essential transmitters.

The forearm flexors and grip musculature are important not because these muscles create a great deal of joint rotation to accelerate the racket, or because grip forces increase ball impulse, but because the energy from the lower body and trunk must be transferred to the racket in the later stages of the stroke.

Research on grip style shows that force production was significantly greater with an eastern grip at early, mid, and late contact than with other grips, and force was greater for men at all contact points.

​

---

Summary

Power in the tennis forehand emerges from a tightly orchestrated sequence: legs drive into the ground, the pelvis rotates, the upper trunk follows with a separation angle that pre-loads the trunk muscles eccentrically, this elastic energy is released explosively as the shoulders rotate forward, the arm lags and then accelerates through shoulder internal rotation and horizontal adduction, and the wrist finalizes the transfer to the racket head. Disruption anywhere in this chain — a weak core, poor timing, or a rushed backswing — measurably reduces racket-head speed, because each proximal segment must peak before the next distal one begins its acceleration phase.

 

[MGArchitect]

Part 2 of 3

This appears to be a good summary, but I do not understand which leg is generating the force, or why the swing is not actually initiated by the shoulder or trunk rather than the legs.

Great questions — let me address both directly, drawing from the research.Two excellent questions. Let me address each one clearly.

---

​

Which Leg Is Generating the Force?

The answer depends on which stance the player uses — and this is an area of active research. There are two main stances in the modern game:

In the square (or neutral/closed) stance, the player steps into the ball with the front foot (for a right-hander, the left foot steps toward the net). Here, vigorous extension of the lower extremity in classic closed-stance forehands creates greater axial torques to rotate the pelvis and hips. Research indicates that lower extremity motion is more important for generating power in the closed-stance forehand than in the open-stance forehand. The knee extension of both legs contributes, but the driving leg pushes off the ground to propel rotational momentum forward.

In the open stance (which is now the dominant style, used 60–70% of the time on the professional tour), the player's hips remain roughly parallel to the baseline, and the footwork picture changes considerably. Here, the rear leg drive is mainly responsible for the pelvis and the later trunk rotation in the tennis forehand. Peak values of rear leg extension almost coincided with maximum pelvis angular velocities in the high-performance group. For a right-handed player in open stance, this means the right leg (the back, dominant-side leg) is the primary force producer. Research on plantar pressure supports this: due to higher force in the dominant leg, a higher rotation in the pelvis and trunk is achieved, resulting in higher stroke speed.

In short: in the open stance, the rear (dominant-side) leg drives the pelvis rotation; in the closed/square stance, both legs contribute, with leg extension propelling forward linear momentum that converts to rotation at the hips.

---

​

Why Don't the Shoulder and Trunk Initiate the Swing?

This is a genuinely interesting question — and the physics answer is counterintuitive.

The reason the legs must initiate, rather than the shoulders or trunk, comes down to Newton's Third Law and force origin. The body can only generate force against an external resistance. The only such resistance available during a forehand is the ground. Muscles acting at the shoulder or trunk have nothing to "push against" unless the segments below them are already anchored and loaded. The ground is the only place where the body can exchange force with the external environment, and that force is delivered through the feet.

The process begins with ground reaction forces that are channeled through the legs and hips, accelerating the pelvis. The trunk then acts as a force-transmitting and force-multiplying link. The shoulder and arm cannot bypass this — they are literally downstream of the trunk, which is downstream of the pelvis, which is downstream of the legs and ground. Initiating from the shoulder would be like trying to crack a whip from the tip rather than the handle.

There is also a crucial energy efficiency argument: research at the University of Tokyo identified the importance of internal extensor moments at the back hip in forehand strokes, and the importance of hip (pelvic) rotation has been highlighted in both forehand and backhand strokes. If the trunk fired first without the pelvis being pre-rotated by the legs, there would be far less elastic energy stored in the trunk muscles to explosively release — the stretch-shortening cycle would be undermined.

Finally, shoulder speed has been shown to contribute only about 25% of racket speed. The rotation of the upper arm, forearm, and hand account for the remaining 75%. The shoulder's role is as an amplifier and director of energy already arriving from below, not as the engine itself. Starting the swing at the shoulder would essentially skip the largest source of energy in the chain.

So the sequence — ground → legs → pelvis → trunk → shoulder → arm → racket — is not arbitrary. It is dictated by physics: each segment can only accelerate effectively once the segment below it has peaked and begun to decelerate, transferring its momentum upward in the chain.

 

[MGArchitect]

Part 3 of 3

So that explains how the biomechanics work, but how about how our brains initiate the movement? Are they thinking about racket and hand location first and not about all the other items?

Great question — this moves from biomechanics into motor control and neuroscience. Let me search the scientific literature on this.This is a rich area that bridges motor neuroscience and cognitive psychology. Here is what the science says.

---

​

How the Brain Initiates the Tennis Forehand

Your intuition is essentially correct — and it is one of the most important findings in sports motor neuroscience. Expert players are not consciously thinking about their legs, hips, or trunk at all. Their brains are focused outward, and the biomechanical chain runs automatically underneath conscious awareness.

---

​

The Brain Thinks in Goals, Not Body Parts

The key scientific framework here is the Constrained Action Hypothesis, developed by Wulf and colleagues. The hypothesis holds that an external focus facilitates motor performance because it promotes automatic control of movement. By contrast, adopting an internal focus of attention induces more deliberate and conscious control of movement, thereby constraining or disrupting normal automatic control processes.

In practical terms, an "external focus" means thinking about the ball, the target, or the racket's effect on the ball. An "internal focus" means thinking about your legs, hips, grip, or swing path. Research in racket sports specifically confirms that an external focus benefits the learning and performance of racket sport skills compared to an internal focus. The findings suggest that coaches and practitioners should consider the adoption of an external focus to optimize racket sports performance.

So yes — the brain of a skilled player is focused primarily on the ball and the target, not on the sequence of body segments producing the stroke.

---

​

Why Thinking About Body Parts Actually Hurts Performance

This is not merely a coaching preference — it has a neurological explanation. Focusing on movement mechanisms evokes self-consciousness in the performer and triggers attempts to control automatized motor processes, resulting in performance impairment. There is even neuroimaging evidence for this: an internal focus promotes conscious motor processing in the form of increased coherence between verbal, analytical, and motor planning brain regions. Essentially, thinking about your hip rotation recruits the analytical, language-based parts of your brain — exactly the wrong tools for executing a fast, coordinated movement.

This also explains the phenomenon of "choking under pressure." The phenomenon of "choking under pressure" is theorized to occur when a performer tries to consciously apply declarative motor knowledge to an action that had become automatized at an implicit level. A player who normally hits their forehand fluidly can fall apart the moment they start consciously analyzing it — a coach's overly technical mid-match advice can literally disrupt what was working.

---

​

What the Expert Brain Is Actually Doing: Forward Models

At a deeper neural level, expert tennis players have built what neuroscientists call internal forward models — predictive simulations of their own movement and its consequences, stored largely in the cerebellum and superior parietal cortex. Tennis players are required to predict the effect of an opponent's motion on ball trajectory by using forward models that allow rapid processing of incoming sensory stimuli. This offers the acting individual a clear advantage in producing a quick motor response, which is mandatory in both sports.

The superior parietal cortex during action prediction is associated with the storage of internal models and perceptual-motor representations. These models allow the brain to issue a single high-level motor command — essentially "hit the ball to that location" — and the cerebellum and motor cortex fill in all the lower-level details of the kinetic chain automatically, without conscious direction.

---

​

The Novice vs. Expert Distinction

This distinction is critical for understanding skill development. When novices focus on proximal aspects, such as racket motion, they attune to specific perceptual information and assemble optimal coordination patterns. Experts, by contrast, have internalized those patterns and shift attention outward entirely. The research on motor imagery reinforces this: when expert tennis players mentally rehearse a stroke, motor imagery focused on the trajectory of the ball and the target area — not the body mechanics — produces better performance outcomes.

---

​

What This Means in Practice

The picture that emerges from the science is that the kinetic chain we discussed earlier — legs, pelvis, trunk, shoulder, arm, racket — runs as an automatic subroutine. The expert brain sends a goal-level command ("intercept that ball at this location with this pace"), and the motor system executes the entire biomechanical sequence without requiring conscious step-by-step instruction. Thinking explicitly about any link in that chain — "drive with my right leg now," "rotate my hip now" — actually interferes with the very automatic processes that make it work.

This is why elite coaching at advanced levels focuses overwhelmingly on ball recognition, tactical positioning, and outcome cues rather than body mechanics. The mechanics have to be trained into automaticity first, largely through repetition, so that by match play the brain is free to focus entirely on the ball.

 

[ballmachineguy]

tl;dr

 

[liimey86]

I was going to reflexively complain about AI slop. Instead I ended up reading the whole thing, despite the length. (Nice set of prompts, btw.)

I appreciated the AI's use of the more relevant term "pelvis" (vs just saying hip or hips) regarding ground force -> trunk rotation. Also its mention of the term "shoulder girdle".

I'm still mixed on what percentage of a current LLM's output may be hallucination, but those first two sections appear (to my bias) to be quite well said/explained, imo.

 

[MGArchitect]

I was going to reflexively complain about AI slop. Instead I ended up reading the whole thing, despite the length. (Nice set of prompts, btw.)

I appreciated the AI's use of the more relevant term "pelvis" (vs just saying hip or hips) regarding ground force -> trunk rotation. Also its mention of the term "shoulder girdle".

I'm still mixed on what percentage of a current LLM's output may be hallucination, but those first two sections appear (to my bias) to be really well said/explained, imo.

it actually gave me all the links/footnotes as well, but those got lost when I hit the copy button. So pretty good at directing you to where information might be coming from. I've been on the AI fence, but if you prompt it well, I find I like it. Still not sure about generative AI, but for summarizing topics, it's great.

 

[10sbeast888]

'how brain initiates' is all that matters.

"ball and target" is close enough.. but what is the closest to the ball? the hand. Therefore the sequence starts with the hand.

the kinetic chain, initiated from the ground or not, has no learning/coaching value.

 

[ppma]

There is stuff that is misleading like that role of the trunk as force multiplier but well...

Nice trolling on the 2947473th thread on the same topic. I won't argue in this one lol

 

[10sbeast888]

There is stuff that is misleading like that role of the trunk as force multiplier but well...

Nice trolling on the 2947473th thread on the same topic. I won't argue in this one lol

what? I won?

you can not be serious.

 

[liimey86]

There is stuff that is misleading like that role of the trunk as force multiplier but well...

I noticed that strange 'trunk as force multiplier' phrase as well. Maybe it means something about being more distal to the legs, but regardless, I too wouldn't waste any time debating over an LLMs output.

 

[ppma]

what? I won?

You won what?

 

[ProStaffFanatic]

You won what?

His made up game

 

[ProStaffFanatic]

Overall it seems like a fairly decent explanation to me.

Especially the part about how the brain operates in novice vs experienced players.

Novice players will be more busy with actual mechanics, while those who have already internalised mechanics (muscle memory) will rather think about ball quality they shoot for and the body will just do what is needed on basically auto-pilot.

 

[GrandSlammer]

it actually gave me all the links/footnotes as well, but those got lost when I hit the copy button. So pretty good at directing you to where information might be coming from. I've been on the AI fence, but if you prompt it well, I find I like it. [..]

You can share the chat so everyone can see the entire conversation, including sources. Then it's only one link in the OP and it saves all that c&p!

I did something similar with ChatGPT when trying to steelman @10sbeast888's argument about the KC starting with the hand:

Check out this chat

Here's a chat someone thought you'd want to see.

chatgpt.com

LLMs will all return the same result on this particular topic imo (give or take), since there is a relatively standardised and accepted body of literature. I see @ppma doesn't like the trunk force multiplier concept. Anyway, unless some new revolutionary study comes along and blows it all out of the water, not much will change.

@ballmachineguy has already acknowledged he thinks it is all wrong.

Another one of those so-called-coaches talking about leg drive, hip firing, and this silly KC stuff. I mean, you watch him and others, or research and study the science of it, but you know based on TTW how wrong they are. Sad days.[..]

Great post!

 

[Chas Tennis]

Part 1 of 3
..................................................................

---

....................................................................
Summary

Power in the tennis forehand emerges from a tightly orchestrated sequence: legs drive into the ground, the pelvis rotates, the upper trunk follows with a separation angle that pre-loads the trunk muscles eccentrically, this elastic energy is released explosively as the shoulders rotate forward, the arm lags and then accelerates through shoulder internal rotation and horizontal adduction, and the wrist finalizes the transfer to the racket head. Disruption anywhere in this chain — a weak core, poor timing, or a rushed backswing — measurably reduces racket-head speed, because each proximal segment must peak before the next distal one begins its acceleration phase.

Words Plus Videos.

Did you have a summary reference for all this or did you create it? What is the earliest source reference?

If you showed a video of an ATP forehand and matched your comments to parts of the video or times of the video, we could all follow along.

In other words, high speed videos along with detailed comments together are very good for communicating tennis strokes (and everything else involving objects and motions). The forum can do that and a book can't.

Video does not have to leave anything out. Maybe you need two camera angles on some things.

You can start a video the first time from any frame and select a Youtube link to do that. Could you try and match 5 times of your word description to video frames? (The forum only allows 5 videos per post.) Start with one clear sub-motion or sub-motions.
_________________________________________________________________________________

"the transfer of energy from the ground upward through successively faster body segments."

My problem with the Kinetic Chain Concept is how poorly it handles the Stretch-Shorten-Cycle. It is not successively faster segments. For example, the take back can transfer energy into stretched torso muscles and stop the upper body and then use that elastic energy to help accelerate the forward swing. The segments can stop.

The Kinetic Chain Concept is an early thought - often said by those now wishing to impress - that is not very complete. Get the original book by John W. Bunn that is frequently referenced, Scientific Principles of Coaching. The original book was printed in 1955 and my 2nd edition 1972. My phone has information when I ask What did John Bunn have to do with the Kinetic Chain Concept.

Biomechanics - on the other hand - is a science that adopts new things when they have become understood. Is there a quote for the speeding up of segments in B. Elliott's work? Of course, Elliott & Marshall said that ISR was the "missing link" in the tennis serve to point out and emphasize that the Kinetic Chain Concept missed ISR! I did see the Kinetic Chain Concept term said, but it always lacks the Stretch Shorten Cycle that is always significant in current biomechanics. KCC is a past scientific view from decades ago. Bunn wrote an interesting coaching book. It was for 12 sports including tennis. Bunn was a basketball coach. Of course he did not catch ISR in tennis serving and neither did any tennis biomechanics researchers that might have applied the Kinetic Chain Concept to the tennis serve.

Some popular views of the past have gone out of usage, but not the old Kinetic Chain Concept.

Exceptions to the Rule Everywhere in Athletics. On the serve, the leg thrust causes ESR at the shoulder joint through many slow body segments. That muscle stretch of ISR muscles is then used for the most significant racket head speed in tennis for impact. Tell us how those slow segments pass on speed for that ESR-ISR sub-motion with the Kinetic Chain Concept. Sometimes when your ask a direct question and get no answer, there's a reason for no answer......

Can one brief sentence explain all athletic motions with a segment speed theory from the 1950s?

Leg thrust slow - body up slow - shoulder joint ESR slow - stop with pre-stretched ISR muscles - ISR to impact fast. Where are the speeding segments? I don't see them. Where is the Stretch Shorten Cycle? In the ESR-ISR sub-motion & other sub-motions. In athletics, everywhere. Walking around the house, everywhere. Athletes exaggerate the SSC for speed. Athletes might be SSC Specialists, almost by definition. Look at some pictures of baseball pitchers to see body exaggerations.

See a video.

To single frame on Youtube, stop video, go full screen, use the period & comma keys.

 

[MGArchitect]

@Chas Tennis I did not create this. This was generated by my chat with Claude, Anthropic’s AI.

@GrandSlammer Here is the link to the chat which includes links to various scientific papers: https://claude.ai/share/01241d52-d53f-4127-a791-b63e695e6946

@ppma and @liimey86 This is a link to the paper that Claude grabbed the reference to the trunk being a force multiplier (paper is from 2025): https://www.ijcrt.org/papers/IJCRT25A1249.pdf

 

[ppma]

@Chas Tennis I did not create this. This was generated by my chat with Claude, Anthropic’s AI.

@GrandSlammer Here is the link to the chat which includes links to various scientific papers: https://claude.ai/share/01241d52-d53f-4127-a791-b63e695e6946

@ppma and @liimey86 This is a link to the paper that Claude grabbed the reference to the trunk being a force multiplier (paper is from 2025): https://www.ijcrt.org/papers/IJCRT25A1249.pdf

Thanks. Appreciate it.
Sadly, it does not elaborate on the force multiplication concept. It is accompanied, however with force tranfering, which I agree.

I think the author means that the core transfers energy from distal to proximal segments and also adds some energy/work of its own. Then it's not a mutiplier but it adds to the existing energy from the bottom. Anyways, sloppy non-rigurous writing there.

 

[Chas Tennis]

e

@Chas Tennis I did not create this. This was generated by my chat with Claude, Anthropic’s AI.

@GrandSlammer Here is the link to the chat which includes links to various scientific papers: https://claude.ai/share/01241d52-d53f-4127-a791-b63e695e6946

@ppma and @liimey86 This is a link to the paper that Claude grabbed the reference to the trunk being a force multiplier (paper is from 2025): https://www.ijcrt.org/papers/IJCRT25A1249.pdf

I did not know that Claude was an AI.
AI tells things that may not be true.

It is possible that AI could contaminate the scientific literature because of the true vs false issue.

Widely held beliefs in tennis are already contaminated by many false beliefs. For example, that most ATP players watch the ball to impact while serving. High speed videos show that most don't. A smaller percentage do watch it to impact. Or that ATP players 'toss the ball over their heads for a kick serve'. They toss the ball to a forward location and move their heads forward and impact the ball over their heads. Videos of a few ATP servers show what is true.

Many false beliefs about tennis strokes are show stoppers as far as performing the tennis stroke at a high level.

If you ask AT about "Pronation Tennis Serve" does it find what is true? Or parrot what is not true because the truth is so muddled in usage.

If 1 o 2 false things that Claude says are believed they may prevent performing a high level stroke as in the ATP.

For example, before 1995 and the discovery of ISR by tennis researchers, AI would probably not have mentioned ISR at all. Does AI mention that the tossing arm is inverted after ball release for the ATP serve? Can AI analyze high speed videos of tennis strokes. Can AI see something new in a video that is not discussed on the internet in searchable words?

Don't worry, humans have an infinity ability to handle any amount of mind clutter in the future.

 

[liimey86]

.

 

[liimey86]

@ppma and @liimey86 This is a link to the paper that Claude grabbed the reference to the trunk being a force multiplier (paper is from 2025): https://www.ijcrt.org/papers/IJCRT25A1249.pdf

The paper looks interesting and I'll likely read through it, but, as an aside.. I'm not familiar with the journal it was published in. Is it just me, or does the name of the journal itself seem a bit sketchy? "International Journal of Creative Research Thoughts".

 

[liimey86]

The paper looks interesting and I'll likely read through it, but, as an aside.. I'm not familiar with the journal it was published in. Is it just me, or does the name of the journal itself seem a bit sketchy? "International Journal of Creative Research Thoughts".

Additionally, since the paper is self described in its abstract as 'systematic review and meta-analysis', vs original research, does that make it potentially more possibly an AI generated paper? Not saying it is, and in fact that might be easily disputed by someone who knows more about that journal and that paper - I'm just wondering aloud in general.

 

[SystemicAnomaly]

The paper looks interesting and I'll likely read through it, but, as an aside.. I'm not familiar with the journal it was published in. Is it just me, or does the name of the journal itself seem a bit sketchy? "International Journal of Creative Research Thoughts".

When I initially looked into this journal, it appeared to be ok:

IJCRT is a Transparent Peer-Reviewed Open Access Journal (Refereed Journal), aligning with UGC & UGC CARE recommendations.

Is IJCRT indexed in Google Scholar?

IJCRT is Scholarly open access journals, Peer-reviewed, and Refereed Journals, High Impact factor 7.97 (Calculate by google scholar and Semantic Scholar | AI-Powered Research Tool), Multidisciplinary, Monthly, Indexing in all major database & Metadata, Citation Generator, Digital Object Identifier(DOI) with Open-Access ...

However, with a deeper dive, I did come across some unsettling feedback:

The International Journal of Creative Research Thoughts (IJCRT) is widely considered by the academic community to be a predatory journal. It exhibits several major red flags common to pay-to-publish schemes, including a lack of rigorous peer review, questionable indexing claims, and aggressive solicitation of submissions.

Key factors to consider include:

• Peer Review Concerns: The journal is known to accept articles almost immediately, which is highly indicative of inadequate or non-existent peer review.
• Indexing Discrepancies: While IJCRT claims indexing in various databases, academics frequently report that their papers are not actually indexed or discoverable in major, reputable platforms like Scopus.
• Impact Factor: The journal often advertises "Impact Factors" that are self-assigned or originate from non-standard, unofficial metric companies (e.g., SJIF).
• UGC-CARE Status: The UGC Consortium for Academic and Research Ethics (UGC-CARE) previously dropped many such journals from their lists due to compromised academic standards.

Because publishing in predatory journals can damage a researcher's academic profile and credibility, it is highly recommended to seek out established, peer-reviewed, open-access journals. You can verify the legitimacy of academic publications using vetting tools like the Directory of Open Access Journals (DOAJ).

https://www.researchgate.net/post/Is-INTERNATIONAL-JOURNAL-OF-CREATIVE-RESEARCH-THOUGHTS-IJCRT-a-genuine-journal

Research Guides: Evaluating Information Sources: Predatory Publishing

Tips on evaluating popular and scholarly articles, bias and propaganda in publishing, impact metrics and predatory publishing.

libguides.usc.edu

 

[ballmachineguy]

Can’t learn one solitary thing about tennis in this thread. Wear your caps and gowns proudly though.

 

[Chas Tennis]

e

Thanks. Appreciate it.
Sadly, it does not elaborate on the force multiplication concept. It is accompanied, however with force tranfering, which I agree.

I think the author means that the core transfers energy from distal to proximal segments and also adds some energy/work of its own. Then it's not a mutiplier but it adds to the existing energy from the bottom. Anyways, sloppy non-rigurous writing there.

What text of the OP or author are you quoting?

In KCC, energy always goes from proximal to distal? ??

 

[ppma]

e

What text of the OP or author are you quoting?

In KCC, energy always goes from proximal to distal? ??

To the two paragraphs that talk about the force-multiplying link. Such thing exists in physics (for example a lever), but there is no body segment that works like that.

Sure, I've not read all about KCT, but in my understanding it speaks about how momentum is taken from the ground into the distal parts. However, there are other ways to hit a groundstroke. E.g. the jack kife does not take momentum from the ground if we leave the jump aside. Instead, the leg kicks to stabilize the body subject to the swing action. However, these are mostly exceptions that do not add up to a significant share of the tennis practice.

I prefer no to talk about energy transfer. Energy is produced stored in the body and converted into kinetic energy in all the parts of the body involved in a shot, so I am not very keen on the idea of "energy transfer". I prefer the idea of momentum transfer (although one could translate that into kinetic energy, but that's another subject). So, here it is essential to understand that whatever musce movement one does, is subject to laws of physics; specifically momentum conservation. Swinging an racquet, if done in isolation, would imply a general displacement of the body back, a counter rotation of the lower body, and a rotation back around the hips axis. For that not to happen KCT explains that the momentum of the swing is taken from a heavier object (ground) and that the forces that are generated against it compensate for the abovementioned motions that would come from swinging.

Words Plus Videos.

Did you have a summary reference for all this or did you create it? What is the earliest source reference?

If you showed a video of an ATP forehand and matched your comments to parts of the video or times of the video, we could all follow along.

In other words, high speed videos along with detailed comments together are very good for communicating tennis strokes (and everything else involving objects and motions). The forum can do that and a book can't.

Video does not have to leave anything out. Maybe you need two camera angles on some things.

You can start a video the first time from any frame and select a Youtube link to do that. Could you try and match 5 times of your word description to video frames? (The forum only allows 5 videos per post.) Start with one clear sub-motion or sub-motions.
_________________________________________________________________________________

"the transfer of energy from the ground upward through successively faster body segments."

My problem with the Kinetic Chain Concept is how poorly it handles the Stretch-Shorten-Cycle. It is not successively faster segments. For example, the take back can transfer energy into stretched torso muscles and stop the upper body and then use that elastic energy to help accelerate the forward swing. The segments can stop.

The Kinetic Chain Concept is an early thought - often said by those now wishing to impress - that is not very complete. Get the original book by John W. Bunn that is frequently referenced, Scientific Principles of Coaching. The original book was printed in 1955 and my 2nd edition 1972. My phone has information when I ask What did John Bunn have to do with the Kinetic Chain Concept.

Biomechanics - on the other hand - is a science that adopts new things when they have become understood. Is there a quote for the speeding up of segments in B. Elliott's work? Of course, Elliott & Marshall said that ISR was the "missing link" in the tennis serve to point out and emphasize that the Kinetic Chain Concept missed ISR! I did see the Kinetic Chain Concept term said, but it always lacks the Stretch Shorten Cycle that is always significant in current biomechanics. KCC is a past scientific view from decades ago. Bunn wrote an interesting coaching book. It was for 12 sports including tennis. Bunn was a basketball coach. Of course he did not catch ISR in tennis serving and neither did any tennis biomechanics researchers that might have applied the Kinetic Chain Concept to the tennis serve.

Some popular views of the past have gone out of usage, but not the old Kinetic Chain Concept.

Exceptions to the Rule Everywhere in Athletics. On the serve, the leg thrust causes ESR at the shoulder joint through many slow body segments. That muscle stretch of ISR muscles is then used for the most significant racket head speed in tennis for impact. Tell us how those slow segments pass on speed for that ESR-ISR sub-motion with the Kinetic Chain Concept. Sometimes when your ask a direct question and get no answer, there's a reason for no answer......

Can one brief sentence explain all athletic motions with a segment speed theory from the 1950s?

Leg thrust slow - body up slow - shoulder joint ESR slow - stop with pre-stretched ISR muscles - ISR to impact fast. Where are the speeding segments? I don't see them. Where is the Stretch Shorten Cycle? In the ESR-ISR sub-motion & other sub-motions. In athletics, everywhere. Walking around the house, everywhere. Athletes exaggerate the SSC for speed. Athletes might be SSC Specialists, almost by definition. Look at some pictures of baseball pitchers to see body exaggerations.

See a video.

To single frame on Youtube, stop video, go full screen, use the period & comma keys.

KC comes from applied mechanics leaving aside concepts that relate more to living organisms motion mechanisms or muscle/joint specific motions. Instead, it talks about where momentum is taken and how that translates into the desired motion in a dynamic balance. IMO, that relates much about general mechanics, while biomechanics sets its focus on the specific operation of joint motions. Think both approaches see things from different perspectives that complement.

 

[Chas Tennis]

............................................................................

I think the author means that the core transfers energy from distal to proximal segments and also adds some energy/work of its own. ..............................

You are saying what someone means by saying something that is not identified.

1) What was said?

AND

2) What did you mean by

"I think the author means that the core transfers energy from distal to proximal segments....."?


Using direct quotes takes care of many communication problems.

 

[ppma]

You are quite an exhausting poster.

 

[user92626]

You are quite an exhausting poster.

a new MEP ?

 

[liimey86]

.

 

[ShinMezame]

Gonna have to disagree. I have it on very reputable authority that the kinetic chain starts from the hand.

 

[Chas Tennis]

AI presented a large number of statements often with what sounded like confidence, like most forum posters. If there were X statements, how many were false?

Reminds me of a turd in soup.

 

[SystemicAnomaly]

Gonna have to disagree. I have it on very reputable authority that the kinetic chain starts from the hand.

All we really know at this point is that the KC started with the Big Bang... the original mover as we know it. Before that, its all conjecture,

 

[MGArchitect]

Continued the chat….

Link to updated chat: https://claude.ai/share/01241d52-d53f-4127-a791-b63e695e6946

Part 4 of 6

Let’s return to the original topic on tennis forehands. In discussing with some tennis enthusiasts that I know, it was expressed that the kinetic chain may be an outdated concept. Please discuss the evolution of tennis biomechanic research with an emphasis on recent research. Also, exclude resources like the International Journal of Creative Research Thoughts that are known predatory journals.
This is an excellent and nuanced question, and the research literature is genuinely evolving. Here is a careful survey of how the field has developed, and where the real scientific debates now lie.

---

The Evolution of Tennis Forehand Biomechanics Research​

Phase 1: The Kinematic Era (1970s–1990s)​

The earliest systematic biomechanics research on the forehand was primarily descriptive — using film and early motion capture to document joint angles, segment positions, and racket velocities. The primary questions were "what does the stroke look like?" rather than "how does it work mechanically?" Researchers like Elliott at the University of Western Australia were among the first to apply rigorous laboratory methods to tennis strokes, using high-speed cameras to isolate the contributions of individual limb segments. The consensus of this research supports the importance of axial rotation of the pelvis, trunk, shoulder horizontal adduction, and internal rotation as the primary contributors to racket speed in the forehand.

Crucially, this era relied almost entirely on lab-based optical motion capture — players were filmed in controlled settings, often hitting balls fed from machines, not in competitive conditions. The ecological validity of those findings was always a latent limitation.

---

Phase 2: The Kinetic Chain Model Is Formalized (1990s–2010s)​

Through the 1990s and 2000s, the proximal-to-distal sequencing model — what became popularly called the kinetic chain — was systematically established. Elliott and colleagues published influential work showing that energy generated at the ground traveled through the legs, pelvis, trunk, and into the arm and racket. Efficient function, with maximal performance and minimal risk of injury, requires optimum activation of all the links in the kinetic chain designed for power. Injury is often associated with alterations in the flow of energy across segments, such that if one segment is removed from the chain, there is an increased reliance on the others to accommodate this loss, which may lead to tissue overload.

Importantly, this research also revealed that the model was not entirely rigid. Even within this era, work by Knudson showed that selected aspects of the stroke production of high-performance players are variable — an early signal that the strict "chain" metaphor had limitations.

A landmark 2010 Journal of Sports Science & Medicine study by Landlinger and colleagues using an eight-camera Vicon system at 400Hz found that the later occurrence of maximum angular pelvis and trunk rotations were the main reasons for the tendency toward higher horizontal shoulder and racquet velocities in the elite group, confirming that timing of segment sequencing — not just magnitudes — was a key differentiator between elite and sub-elite players.

---

Phase 3: Methodology Shifts and the Dynamical Systems Challenge (2010s)​

A significant intellectual challenge came not from tennis-specific research but from the broader sports biomechanics field, where dynamical systems theory began to offer an alternative lens. Historically, biomechanics research had examined discrete kinematics. However, founded in dynamical systems theory, there is now a general appreciation that movement variability and inter-joint coordination play equally important roles in the execution of assorted movement skills.

The dynamical systems perspective argues that the kinetic chain metaphor is mechanistically misleading — it implies a relatively fixed, domino-like sequence, when in reality skilled movement is better understood as emergent coordinationarising from the interaction of many components (neural, muscular, environmental). Under this view, expert coordination emerges as flexible yet stable — flexible in its use of controlled variations of the different coordinated degrees of freedom and stable, but not rigid, in its ability to efficiently produce effective outcomes.

This was not a rejection of proximal-to-distal sequencing as an observed phenomenon, but a challenge to the rigid causal narrative it carried — particularly the idea that each segment must "fire" in a strict relay-race order.

---

Phase 4: IMU Technology Opens the Real World (2018–Present)​

Perhaps the single biggest methodological advance in recent years is the shift from optical motion capture in laboratories to wearable inertial measurement units (IMUs) on actual courts in competitive conditions. This has substantially changed what researchers can see.

A 2022 study in Sensors (Pedro et al., University of Lisbon) used mini-IMUs to study elite players executing cross-court and inside-out forehands in a competitive environment — a first for this level of ecological realism. The study aimed to quantify and compare the upper limb angular kinematics and its contributions to racket head speed between the cross-court and inside-out attacking tennis forehand of elite tennis players in a competitive environment. It found higher shoulder rotation angular velocity during inside-out shots and differential segment contributions to racket velocity depending on shot direction, advancing understanding of upper limb coordination variability linked to tactical shot variations. This is significant: the relative contribution of body segments varies with tactical shot intent — something lab-based research with fed balls could never capture.

A 2025 study published in Frontiers in Sports and Active Living (van Trigt et al.) using high-end IMUs at 1,000 Hz on Dutch professional players directly tested the kinetic chain assumption and produced one of the most important recent findings: professional players do not strictly follow a proximal-to-distal sequence. Intersegmental timing appears to be less important in the tennis serve compared to the segmental angular velocities. The study found that ball speed was significantly positively associated with peak angular velocities of the trunk and upper arm on both the first and second serve, while the strict timing of handoff between segments mattered less than previously assumed.

---

So Is the Kinetic Chain Outdated?​

The honest scientific answer is: the concept is not wrong, but the way it has been described and taught is likely oversimplified.

What the evidence now supports is a more nuanced picture:

What holds up: The general proximal-to-distal pattern is real and observable. Ground reaction forces are essential. Trunk rotation is a primary driver of racket speed. Disruption of any segment has downstream consequences for performance and injury risk.

What is being revised: The strict "relay race" timing model — where each segment must peak and decelerate before the next one begins — does not appear to describe what professional players actually do. Assessing the kinetic chain of the tennis serve requires multiple biomechanical variables spanning kinematics, kinetics, and temporal coordination — and not all of these elements can be captured using wearable IMUs or portable force plates, reflecting that the full picture remains technically difficult to measure.

Furthermore, the myofascial and connective tissue dimensions of force transfer are increasingly recognized. The concept of the integrated kinetic chain asserts that muscular chains and pathways are interlinked through soft tissue viscoelastic envelopment of polyarticular myofascial chains. These chains can transfer force, provide sensory and neuromotor input, and act like organized muscle synergies. This complicates the simple "bone and joint" picture that early kinetic chain models implied.

The emerging consensus is that the kinetic chain remains a useful pedagogical heuristic but is an incomplete scientific model — particularly its assumption of rigid sequential timing. The field is moving toward frameworks that incorporate angular momentum redistribution, movement variability as a functional (not erroneous) feature, and coordination patterns that adapt dynamically to tactical and environmental demands. These are not replacements for the kinetic chain concept so much as more mechanistically complete versions of it.

 

[MGArchitect]

Part 5.1/6

Thanks for the timeline. Still using scientific resources or professional resources how does this knowledge translate to the teaching and learning of the forehand for beginners to intermediate players and up to advanced players? How can a regular person apply this knowledge?

This is a large body of research to synthesize, so let me organize it carefully by skill level and make the practical implications concrete and actionable.

---

From Research to the Court: Teaching and Learning the Forehand Across Skill Levels​

The biomechanics and motor learning literature, taken together, produce a surprisingly coherent and practical picture. The key insight is that what you should consciously think about, and how practice should be structured, changes fundamentally as you advance. Here is what the evidence says at each stage.

---

Beginners: Build the Contact Point, Not the Chain​

The instinct of many early coaches — and learners themselves — is to teach the forehand as a sequence of steps: "turn your shoulders, step forward, swing through." This is the explicit learning approach, and research reveals it has real limitations, particularly for young learners.

A 2024 Frontiers in Psychology study found that instructions to children to focus attention externally facilitate learning the groundstroke technique significantly better than internal (body-focused) instructions. In practice, this means cues like "hit the ball to that target" or "brush up over the ball" outperform "rotate your hips" or "extend your arm." This aligns exactly with what the motor control research said earlier about the Constrained Action Hypothesis — the finding holds even for novices.

There is also strong evidence for analogy learning at the early stage. Analogy learning can use image-specific signals to reduce conscious processing and alleviate working memory load. Analogical learning is more likely to maintain the stability of motor performance than explicit learning in the presence of stress. A metaphor like "wipe a foggy window with your racket" or "swing in a low-to-high rainbow arc" encodes the biomechanical essentials — low-to-high swing path, contact in front of the body — without overloading the learner with sequential instructions. In a study on children learning the tennis forehand, the group that underwent analogical learning followed by explicit learning performed better compared to other groups, suggesting that for beginners, analogy first and technical detail later is the better sequence.

Equipment and court scaling also matter more than most beginners realize. Research has confirmed the largely positive role of modified courts and balls in increasing the technical proficiency, number, and success of forehand shots of beginner children. Lower-compression balls slow the game down enough that beginners can actually develop proper swing mechanics — rather than flinching at the incoming ball and developing compensatory habits that become entrenched.

Practical takeaway for beginners: Don't think about your hips or feet. Think about the ball, pick a target, and use a simple image for your swing. Start with slower balls and a shorter court if at all possible.

---

Intermediate Players: Explicit Technical Work Has a Window​

The intermediate stage — roughly where a recreational player can rally but has inconsistent power or direction — is where explicit technical instruction becomes more appropriate, but still needs to be applied carefully.

Research on intermediate junior players found that both analogy and explicit instructions produced improvements in accuracy and velocity over a five-week training period, with no significant differences between groups. This suggests that at the intermediate level, either approach can work — but the type of instruction should match what the player is trying to fix.

This is also the stage where the biomechanical research becomes directly applicable to self-correction. The research on skill-level differences consistently shows that different timing of maximum angular pelvis and trunk rotation separated elite from high-performance players, and coaches should focus on proper pelvis and trunk rotation to improve forehand performance. Intermediate players often have reasonable arm mechanics but disconnect the lower body — the pelvis and trunk do not fire before the arm. Drills that isolate and exaggerate hip-trunk separation (hitting balls while keeping the non-dominant arm pointing at the target during the backswing, for example) directly address this documented gap.

The constraints-led approach (CLA), extensively discussed in the ITF Coaching & Sport Science Review, offers a particularly useful framework here. Rather than correcting technique through verbal instruction, the CLA manipulates the task environment to nudge the player's body toward better movement spontaneously. Task, environment, and individual constraints act as boundaries which guide the emergence of skilled movement behavior. The interaction of these constraints can have a dramatic influence on performance. Practical examples include hitting from inside the baseline (which forces a compact swing and earlier preparation), or hitting rally balls fed from a shorter distance (which forces trunk engagement because there is no time to arm-swing).

Practice structure matters too. A 2022 study in the International Journal of Sports Science & Coaching found that motor learning through the distribution of practice among children showed significant improvement in skill acquisition of the forehand shot, confirming that spreading practice sessions out (distributed practice) is more effective for intermediate learners than cramming repetitions into single long sessions.

Practical takeaway for intermediates: This is the window where some technical coaching genuinely helps — particularly around hip-trunk rotation and separation angle. But combine it with constraint manipulation, not just verbal correction. Shorter sessions spread across more days beat long infrequent ones.

---

​

 

[MGArchitect]

Part 5.2/6

Advanced Players: Get Out of Your Own Way​

At the advanced level, the research gives what seems at first like counterintuitive advice: stop thinking about technique during play, and use practice variability to keep the motor system adaptable.

The attentional focus literature is unambiguous here. The body of evidence has shown that external focus of attention rather than internal focus enhances motor skill learning and performance. Within racket sports, effectively directing attention is essential to elicit improvements in athletic performance. For advanced players, any return to internal body-focused thinking during match play actively degrades the automatic processes that produce elite-level strokes.

This connects directly to the dynamical systems findings discussed in the previous response. The recent IMU research showing that professional players do not follow a strict proximal-to-distal timing sequence implies that their movement is adaptively variable, not rigidly programmed — and preserving that adaptability requires practicing in conditions that demand it. Technique and skill are different. What coaching "correct" techniques doesn't take into consideration is that individual, environmental, and task constraints act as boundaries which guide the emergence of skilled movement behavior.

Differential learning — deliberately practicing with exaggerated variations (hitting with an extremely open stance, then extremely closed; with a very low contact point, then very high) — is emerging as an evidence-supported method for advanced players. In the case of learning a tennis forehand stroke, the focus should be on performing the forehand with an extended elbow, then with a flexed elbow, then stiff knees, and so on, deliberately exploring the movement solution space. This approach keeps the motor system adaptively calibrated rather than locked into a single pattern.

For advanced players working on power specifically, the biomechanical evidence points to the rear leg drive and the separation angle (hip-shoulder differential) as the two most productive targets — not arm mechanics, which are typically already well-developed. A 2024 study found that the shoulder-hip angle of high-level tennis players is significantly greater than that of ordinary tennis players — meaning that actively training the separation between hip and shoulder rotation during the backswing is a measurable differentiator of performance level.

Practical takeaway for advanced players: In matches, keep your attention external — ball, target, opponent. In practice, deliberately vary constraints and exaggerate different aspects of the stroke rather than grinding the same technique repeatedly. If you want more power, work on the rear leg drive and shoulder-hip separation, not the arm.

---

The Universal Thread Across All Levels​

One finding cuts across all skill levels and is probably the single most actionable piece of research: practice structure and the nature of feedback matter as much as, if not more than, the technical content of instruction. Whether you are a beginner using analogy cues, an intermediate working on hip rotation, or an advanced player using differential learning, the consistent finding is that frequent external feedback given after every repetition slows long-term learning — because the learner becomes dependent on it. Research across motor learning consistently supports reduced, summary feedback (given every few repetitions) and self-directed error detection as superior for durable skill development. The body, when given slightly ambiguous or varying problems to solve, learns to self-organize more robustly than when it is given a perfect template to copy.

In short, the research suggests that the best tennis practice — any level — looks less like drilling a perfect technique and more like solving varied problems within a well-designed environment.

 

[MGArchitect]

Part 6.1/6

Many people learning and developing tennis started as adults, how does learning at these different levels differ for adults versus children?
This is a rich question, and recent research has substantially overturned several popular assumptions about adult versus child learners. Let me lay out what the evidence actually says.

---

Adult versus Child Learning of Tennis: What the Research Shows​

First, Challenging a Popular Myth: The "Golden Age" Is Not What It Seems​

A widely held belief among coaches and sporting organizations is that there is a special pre-pubescent "golden age" — roughly ages 6 to 12 — during which motor skills are learned uniquely fast and that adults who start later are fundamentally disadvantaged. The scientific evidence is considerably more nuanced.

When comparing motor learning between children and adults, studies have typically found little difference or differences favoring adults. Studies that have reported precocious learning within the so-called golden age appear not to have controlled all relevant variables — the different age groups typically have not started from similar baselines and tested tasks that have not been scaled according to physical differences. A 2020 Frontiers in Psychology study that carefully controlled for baseline performance found no significant differences in motor learning between 10-year-olds, 18-year-olds, and 40-year-olds when each group started from a comparable starting point and tasks were scaled to body size.

This was reinforced by a landmark 2024 Developmental Science study from the University of Copenhagen testing 132 participants across four age groups. Contrary to common beliefs, adults can learn new motor skills faster than children, but children retain these skills better due to more effective sleep-driven memory consolidation. During the training session itself, both the 16–18-year-olds and 20–30-year-olds improved their skills significantly more than the 8–10-year-olds.

The key distinction is therefore not whether adults can learn, but how learning and retention differ mechanistically — and this has direct practical implications.

---

Where Children Have an Advantage: Sleep and Consolidation​

The genuine edge children hold over adults is not in the training session itself, but in what happens afterward. School-aged children show training-dependent gains in performance in the hours after a practice session, even without further practice. These positive gains were retained two weeks later. These behavioral findings indicate different underlying post-training processes in children's and adults' motor skill learning, supporting differential tutoring of skills.

The youngest learners are better at consolidating and reinforcing memory after they have practiced — sleep appears to play a particularly powerful role. Adults' mature cognitive abilities likely contribute to faster learning during sessions, while children's sleep architecture aids longer-term memory consolidation.

What this means practically is that children benefit enormously from short, frequent sessions with adequate sleep between them — their brains are doing consolidation work offline. Adults, by contrast, do more of their learning during the session and rely more on accumulated deliberate practice for retention.

There is also an important interference finding relevant to adult learners. The establishment of a memory trace for a trained movement sequence was significantly more susceptible to interference by a subsequent motor learning experience in older adolescents compared to younger children. Unlike older groups, younger children showed significant delayed gains even after exposure to interfering tasks. Adults learning multiple new motor patterns in the same session — for instance, a forehand and a backhand in the same lesson — are more vulnerable to having each pattern interfere with the consolidation of the other. Children are more resilient to this.

---

Where Adults Have Real Advantages​

Adults bring substantial resources to motor learning that children do not have, and these are often underappreciated.

Cognitive leverage. Adults have more developed working memory, more sophisticated metacognition (awareness of their own learning), and a greater capacity for explicit instruction. This is why explicit instructions produced improvements in accuracy and velocity in intermediate junior players, but the same explicit instruction proves even more effective for adult learners, who can map technical cues to body awareness more efficiently. An adult being told "your hip rotation is initiating too late" can understand and act on that feedback in a way a young child cannot.

Transfer from existing movement experience. Adults who have participated in other sports or physical activities carry a reservoir of existing movement patterns — rotational sports like baseball or golf, for instance, develop trunk rotation mechanics that transfer meaningfully to the tennis forehand. Variable practice conditions and experience in different sports allow for a repertoire of functional movement skills to be developed. This variability enhances the long-term retention of motor programs and leads to benefits in transfer situations, where skills learned in one context can be applied to another. Coaches working with adult beginners can explicitly bridge from existing movement knowledge: "this hip-shoulder rotation is similar to a baseball swing or throwing a ball."

Motor imagery. Adults also use motor imagery (mental rehearsal) far more effectively than young children, whose imagery capacities are still developing. Mental visualization is effective in augmenting the acquisition of motor skills. The mental representation of an action and its overt execution are functionally indistinguishable, except for the activation of the terminal actuator. An adult can meaningfully supplement on-court practice with mental rehearsal — visualizing the stroke sequence between sessions — in ways that younger children cannot reliably do.

---

The Adult-Specific Challenge: Overwriting Existing Habits​

Adults who are not complete beginners face a challenge children largely do not: they have entrenched motor patternsthat must be modified, not simply built from scratch. This is neurologically more demanding than clean acquisition.

In the initial stage, a learner is described as locking or "freezing" their degrees of freedom in order to create a motor solution because they have not yet attuned to the relevant task variables. Following practice, degrees of freedom are gradually released to form more efficient coordination patterns. The problem for adults modifying an existing stroke is that their degrees of freedom are not frozen — they are already locked into a habitual pattern, and the nervous system resists overwriting it, particularly under pressure or fatigue when the old pattern reasserts itself.

This is directly relevant to intermediate adult players who developed their forehand through recreational play without coaching, and now want to add more power or topspin. Their brain has automated a motor program that, while inefficient, is deeply consolidated. Research on this "relearning" challenge consistently shows that the constraints-led approach — manipulating the environment to make the old pattern unrewarding and the new pattern necessary — is more effective than telling an adult what to change, because explicit verbal correction actually reactivates the very conscious processing that interferes with motor automaticity.

 

[MGArchitect]

Part 6.2/6

---

Age Within Adulthood: The Older Adult Learner​

The picture changes again for older adults (generally 50+). There is a general age-related decline in neural plasticity, and an age-related deterioration in motor performance that is more pronounced with increasing task difficulty, accompanied by a more bilateral activity pattern in older adults' brains. This does not mean older adults cannot learn — they demonstrably can — but it means the learning process is slower, more effort-dependent, and more sensitive to fatigue.

Critically, sleep consolidation also weakens with age. Sleep-related benefits for motor memory consolidation appear to be predominantly absent in healthy older adults, a result that is at least partially linked to age-related degradations in sleep architecture. This is one of the stronger arguments for older adult learners to prioritize practice session structure — shorter, more focused sessions with longer recovery intervals — rather than trying to match the high-volume training that younger adults can sustain.

---

Practical Summary by Learner Type​

Pulling this together into actionable guidance:

Adult beginner (no prior tennis): The research suggests you can learn faster per session than a child, but you consolidate less efficiently overnight. Prioritize short, frequent sessions over occasional long ones. Use your cognitive advantages — explicit technical instruction, video review, mental rehearsal between sessions — rather than assuming you need to "feel it out" the way children do. Seek coaches who bridge from movement patterns you already know.

Adult intermediate (self-taught habits to modify): This is the hardest position, neurologically. Explicit correction alone is insufficient — it tends to produce short-term awareness without durable change. Constraints-based drilling (practice conditions that make the old habit unworkable) is more effective. Expect regression under pressure; your nervous system will revert to the consolidated pattern when stressed. This is normal and not a sign of failure — it is the known behavior of a system consolidating a competing motor program.

Adult advanced (refining under performance pressure): The motor control and attention literature discussed earlier applies most directly here. Systematic variability in practice, external attentional focus during performance, and deliberately avoiding over-analysis of technique during match play are the evidence-supported levers.

Older adult (50+): Reduce session duration and increase recovery time between sessions. Prioritize sleep quality. Keep instruction simple — complexity taxes a system that is working harder per unit of learning. The enjoyment and social dimensions of the sport matter more at this stage: motivation and consistent participation are stronger predictors of long-term skill maintenance than any specific technical intervention.

 

[10sbeast888]

pretty good chat.

- relay race is dead;
- train the hand first, make sure the WW is real;
- the event chain starts with the hand, the rest of the body responds.

that's the TLDR.

I was right from day 1.

 

[ppma]

Hahahah

Did not read but I was always right

Non-spoiler: no.

 

[AnyPUG]

pretty good chat.

- relay race is dead;
- train the hand first, make sure the WW is real;
- the event chain starts with the hand, the rest of the body responds.

that's the TLDR.

I was right from day 1.

Absolutely correct. It all starts with hand skill as coaches who know what they are talking about teach.
This is just one example. What does he teach first? That's right, the hand skill.

 

[MGArchitect]

pretty good chat.

- relay race is dead;
- train the hand first, make sure the WW is real;
- the event chain starts with the hand, the rest of the body responds.

that's the TLDR.

I was right from day 1.

only item 1 in your list comes from the chat. Whether true or not, the other 2 are your own and not from the chat with Claude.

 

[liimey86]

Absolutely correct. It all starts with hand skill as coaches who know what they are talking about teach.
This is just one example. What does he teach first? That's right, the hand skill.

Watching the first 2 minutes of that EssentialTennis video, the coach is having players literally "turn the doorknob", actively with their forearm and wrist and without any help from an "already moving racquet". That looks like wrist injury just waiting to happen. Whether he means it literally, or if players assume he meant it literally but didn't.

 

[liimey86]

Continued the chat….
Part 4 of 6

A number of interesting ideas in here (assuming none of the output is hallucinated). Personally, I find the below interesting info for improving at tennis. (I have previously asked Gemini about inverse dynamics approach to tennis biomechanics and got a more detailed answer about the varying kinds of muscle activations we utilize in tennis strokes, including the below.)

Furthermore, the myofascial and connective tissue dimensions of force transfer are increasingly recognized. The concept of the integrated kinetic chain asserts that muscular chains and pathways are interlinked through soft tissue .. chains. These chains can transfer force, provide sensory and neuromotor input, and act like organized muscle synergies. This complicates the simple "bone and joint" picture that early kinetic chain models implied.

 

[liimey86]

Part 5.2/6

This seems actionable as well (tho perhaps its known and obvious to all the coaches out there):

Differential learning — deliberately practicing with exaggerated variations (hitting with an extremely open stance, then extremely closed; with a very low contact point, then very high) — is emerging as an evidence-supported method for advanced players.

 

[AnyPUG]

Watching the first 2 minutes of that EssentialTennis video, the coach is having players literally "turn the doorknob", actively with their forearm and wrist and without any help from an "already moving racquet". That looks like wrist injury just waiting to happen. Whether he means it literally, or if players assume he meant it literally but didn't.

I guess it takes some training to watch tennis videos and undestand what's going on. He didn't move his wrist joint one bit. He rotated the arm from the shoulder joint with a bit of additional rotation around the eblow.
He demonstrated the long axis rotation to spin the ball up, like here -

 

[liimey86]

He demonstrated the long axis rotation to spin the ball up, like here -

If you watch the few seconds of that ET video starting at this timestamp (below) .. I don't think that's ISR. That is dangerous wrist (forearm with stiff wrist) WW to me, no?

www.youtube.com/watch?v=aSiguvqibjs&t=80s

 

[AnyPUG]

If you watch the few seconds of that ET video starting at this timestamp (below) .. I don't think that's ISR. That is dangerous wrist (forearm with stiff wrist) WW to me, no?

www.youtube.com/watch?v=aSiguvqibjs&t=80s

He was a college player and a coach with 2 decades of teaching experience. Trust him over what you can conjure up (unless you have had better tennis qualifications)

 

[liimey86]

He was a college player and a coach with 2 decades of teaching experience.

Yes. I watched a lot of his videos when I was starting out a few years back. He's a nice guy and I bet he helps lots of rec players with clear issues. He's not my cup of tea anymore, but that's here nor there.

 

[AnyPUG]

Yes. I watched a lot of his videos when I was starting out a few years back. He's a nice guy and I bet he helps lots of rec players with clear issues. He's not my cup of tea anymore, but that's here nor there.

I can tell you with 100% certainty that you have barely scratched the surface of what these advanced players and coaches have been trying to teach - not even 10%. You will realize one day and hopefully that day will come soon and won't take 5-7 years of self help experimentation.

 

[liimey86]

I can tell you with 100% certainty that you have barely scratched the surface of what these advanced players and coaches have been trying to teach - not even 10%. You will realize one day and hopefully that day will come soon and won't take 5-7 years of self help experimentation.

All good.