Because you mentioned 'anaerobic' my replies have been oriented to that interesting subject. I used to eat lunch at 12 and then play tennis at 4:30 PM after work. My energy in the 2nd set would crash. I believe that nutrition timing issues are often related to losing energy in a tennis match.
Another issue is that heavy exercise requires recovery time, the over training that you mention. That is less related to the nutrition timing and more related to allowing muscles time to recovery. For circuit training + tennis both nutrition and time for muscle recovery seem important.
When I was younger I would play a lot of singles tennis throughout the summer. By each August my thighs would have increased in size. The size increase indicated that the tennis alone was causing quad hypertrophy and probably some recovery after matches would have been called for. My doubles now does not produce quad hypertrophy, I need the gym for that.
In other words, I don't know how much rest is good when doing both circuit training and tennis. But I would be especially aware both of the glycogen nutrition issue and muscle recovery.
Taking your question to the next level there have been TW threads on 'periodization' for goals of serious muscle hypertrophy and tennis. The approach emphasizes each over a different period. I guess that the tennis pros are often using periodization.
Reference: Periodization Training for Sports, T. Bompa, M. Carrera
Last edited by Chas Tennis : 08-21-2012 at 12:41 AM.