Why do I feel pumped after training?

That feeling of tighter shirt after training is normal and easily explained.

This effect results on the blood that is pumped into the challenged muscles, this situation creates a momentary increased swelling effect, almost as if the muscle has increased in size.

Unfortunately this result lasts about 30 minutes, from that time on the muscles begins to go to their original size.

However regular and supervised training can cause muscle size changes, but for that to happen you need many months of regular training.

Continuation of good workouts!