Fat Burning Cardio Workout Lengths: Which is better?

[Jack the Hack]

For fat burning purposes, does performing two 30 minute cardio workouts in a day equal the same as doing one 60 minute workout?

I have read that a body does not start tapping into fat reserves for energy until about 15-20 minutes into a cardio workout. A Running Magazine article even stated that for maximum weight loss, a person should do 45 minute runs 5 days a week, and a 90 minute run once a week.

In my particular situation, aside from playing tennis for at least an hour 5-6 days a week, I am already doing sprints, agility drills, light weights, and abdominal work, which takes about 30-45 minutes each day. However, to really take a step up with my game and accomplish my tournament goals, I need to lose the extra 25-30 pounds I've been carrying around for the past 5 years. In an effort to do this, in the past month, I have gotten up early in the morning and rode an elliptical ski machine for 30 minutes, followed by stretching, and then one of the weight workouts. I did lose some pounds last month, but thought that I might be able to enhance the weight loss with another 30 minute elliptical ride at night. However, for fat burning purposes, I am wondering if I might be better off doing 60 minutes in the morning and moving the weight routine to later in the day?

I have a feeling that the 60 minute workout might dig into the fat reserves deeper, but that the effect of two 30 minutes workouts (which is more convenient for me) is pretty close.

Does anybody know the real answer?

 

[Ash_Smith]

Get a heart rate monitor and use that to monitor your workout. 60-70% max has slight cardio benefit and some fat burning, 70-80% max has good cardio and fat benefits and 80%+ max is elite level training. These are the rough numbers give or take a % or two. Sustain the required level for the 30 minutes and you'll see the benefit. Max heart rate is 220-age by the way, so a 25 year old would be max 195bpm so 75% would be 146bpm.

 

[forehander]

Jack, that's difficult to say and I think you would hear different responses from different people. On the one hand, it is probably true that you will dip into more fat reserves with a single workout. On the other hand, your metabolism is significantly raised for a time period after you workout, so a morning and evening workout might serve to raise your post workout metabolism for a longer period. The bottom line is, it sounds like you are doing quite a bit of aerobic excersize daily. I'd probably not worry too much about the difference between a single 60 minute and two 30 minute workouts. Instead, focus on your diet and caloric intake. With a healthy diet of around 1800 calories and all of the work you are doing, you should be able to lose about 2 lbs of fat a week. You really don't want to lose faster than that, because if you do, you are probably losing muscle also and that's not good. A healthy loss of 2lbs a week is the way to safely lose fat and keep it off.

 

[CrazyScheiner]

Most effective way to run would be two 30 minutes sessions of MIIT (Medium Intensity Interval Training). A basic version of a workout should be

1 minute of medium (jogging)
1 minute of medium-high (wind sprint)
1 minute of high (full out sprint)
1 minute of low-medium (light jog/fast walk)
5-6 times

Run once in the morning and once in the evening for the most efficent burning. Running in the morning will burn fat rather than glycerin since sleeping burned it off, whcih means you could generally burn 300% more fat, so you would be able to burn about 1000 calories in that run, which reversible would mean that you can burn 1 1/2 lbs of fat from running alone. Always remember to bring water with you and stretch before and after running, which will keep you from getting any stretching injuries. And like forehander said, maintain your diet as well as you can.

Edit: And for people who dont understand how I get 1000 calories, here is the proportion:

Due to the constant changing of running, your body actually puts more effort into burning calories. When burning fat, you burn about 1.5x more then when you are burning carbs so its like this.

175lb man = 650 calories every half hour of running at 8 miles an hour.
Burning fat means 1.5 times more calories when efficently changing speeds.

650 x 1.5 = 975 calories.

Easy, is it not?

 

[Craig Sheppard]

When burning fat, you burn about 1.5x more then when you are burning carbs so its like this.

Where do you get this from? A calorie is a unit of energy... burning 1 calorie is burning 1 calorie no matter what it's made of.

 

[CrazyScheiner]

What I mean is that generally the calories that you will burn from carbs will not effect your weight, but the effect of burning fat like that is more effective. Every carb and protein is 4.5 kCal / gram, but fat is 9 kCal / gram and so when you run it will affect you more. And I forgot where I got the 1.5x thing from, I must have read well over a thousand sites over the last 3 months on lifting, running and dieting.

 

[Jack the Hack]

CrazyScheiner,

Thank you very much for the detailed information!!!

For my weight loss goals, it sounds like I am doing the right thing. The elliptical ski machine I have been doing my cardio on has a 30 minute preprogrammed "Performance Intervals" option, which actually varies the resistance in a simular fashion to what you described. I like doing the elliptical because it works my muscles and does the cardio training without any actual high impact stress on my joints. With the time I am putting on the tennis court and in doing sprints/agility drills, my joints are already getting pounded enough!

 

[goober]

The important part of the equation that you also have to address is your diet. You can workout 5 hours a day, but if you are still consuming more calories than you are burning you will not lose weight. Many failed weight loss attempts result from people subconsciously eating more as a result of increased demand on the body from a new or more vigorous workout regimen.