Tennis Fitness Workout

Question about Sit ups/Abdominal workouts?
Now that summer has started I am playing tennis for 3 hours in the morning and running 4 miles in the afternoon (I’m trying to keep a base for both of the sports). Recently I have had the problem of having a side stitch while I am running, and I believe the problem is that my abs are not strong enough to maintain this level of fitness. My side always feels better if I have been doing sit ups, so I have been doing them daily, but I am not sure how many to do.
I did 100 sit ups yesterday, and I am wondering if it is safe to do 100 sit ups a day?
Thanks
That’s not needed, you’re actually over training your abs. Doing too much could do more damage.
For my ab workout, I train three days a week (mon – wed – fri) for only about 5-8 minutes. I start with 10-15 crunches, and then immediately do some side crunches for your obliques (about 10-15). Then, do some leg raises (also 10-15). Try to do that two times during your workout with no breaks. This will develop your abs nicely without over training. Make sure your diet is good with plenty of protein.