These are muscle cramps associated with exercise ans can occur as little as 10 minutes after high intensity exercise or after one to two hours of exercise.
Exercising in heat, dehydration, decreased concentration of serum electrolytes due to sweating or over consumption of water during exercise, are causes for experiencing these cramps.
Prolonged exercise and intensive one, are more often associated with muscle cramps than short-lasting and less intensive exercises, in other words, muscle fatigue will result in cramps.
He should drink plenty of electrolytic fluid before, during, and after exercise.
He need to practice stretching exercises, especially after the end of his exercising program and should avoid sudden intensive changes in his exercise programe.

When he experiences cramps he should massage the muscle and stretch it gently.

If they appear more frequently he can consult his physician!

ok , somehow im loosing blood when im actually eating fine and drinkin plenty water .I've eating like i always have since then and my doctor say's i have little blood in my body .Its confusing suddenly i have less blood , why is that?