Protein, in doses of about 20 g, is recommended immediately after a workout and through the rest of the 24 hour post-workout period in order to maximize the rate of muscle protein synthesis. Animal sources of protein (meat, eggs, and especially whey) and soy protein are high quality protein choices. It is debated as to whether protein before or during the workout is better than immediately after the workout, so, if it is more comfortable or feels better for you, consuming protein before or during the workout may also have equal benefit.
There have been very few studies on proline as a dietary supplement and cannot be recommended at this time.