With regard to speed or velocity of muscle contraction, one study found that you could combine the two types of work together and realize positive results, but not at high speeds of contractions (like throwing). This is important if you are a speed-power athlete, as your combined training program will hinder your ability to be explosive.
One other study is the gains and maintenance you would expect if you did five weeks of strength training followed by five weeks of endurance training and vice versa. One group looked at this using high velocity contractions and low velocity contractions. It was concluded that no matter which training velocity you are using, you would achieve better results if you do your initial strength work first followed by endurance training. It appears that strength increases are more readily maintained in this sequence.
Simultaneous training appears to compromise strength improvement only when both modes of training engage the same muscle group. If you want to run, I recommend you finish practice first and then try some distance running.
Coach Payan
www.CoachesEducation.com