Muscles need amino acids to grow. You need plenty of them around following a weight workout. Amino acids such as leucine are the building blocks of muscle proteins and serve as signaling chemicals that turn on protein synthesis.

Researchers from Great Britain and the Netherlands found that protein synthesis was 20 percent higher in an exercised leg compared to a non-exercised leg after eating a high-protein meal.

They studied the rate of muscle protein synthesis by measuring the muscle uptake of a labeled amino acid following unilateral leg presses and leg extensions (one leg exercised, while the other was inactive; 8 sets of 10 reps). They took muscle biopsies from both legs.

A practical application of this study would be to consume a high-protein energy bar or shake about 30 minutes before a weight-training workout.