There’s a window of opportunity around workout time where protein consumption enhances muscle protein synthesis above normal levels (in addition to the protein synthesizing effects of resistance training). In this section, we will examine what various researchers have found regarding protein timing. Some authorities have reported that protein timing is just as important as total protein intake. (My note: I doubt that.) 
A session of heavy resistance training increases muscle protein synthetic rates rapidly. MPS rates return close to baseline at approximately 36 hours. Some studies have even suggested that protein synthesis rates stay elevated for up to 48 hours after a heavy resistance training session. If foods containing proteins or amino acids are delivered either immediately before exercise or in the post-exercise period then the rise is greater. If insufficient supplies of amino acids are provided, protein breakdown will exceed protein synthesis and there will be no net accretion of protein.
A study conducted by Tipton showed the delivery of amino acids to be significantly greater during exercise when consumed pre-workout than post-workout (Tipton 2001). The study was designed to determine whether consumption of an oral essential amino acid, carbohydrate supplement (EAC) before exercise results in a greater anabolic response than supplementation after resistance exercise.
Six healthy human subjects participated in two trials in random order, PRE (EAC consumed immediately before exercise) and POST (EAC consumed immediately after exercise). A primed, continuous infusion of L-[ring-(2)H(5)]phenylalanine, femoral arteriovenous catheterization, and muscle biopsies from the vastus lateralis were used to determine phenylalanine concentrations, enrichments, and net uptake across the leg. The results indicated that the response of net muscle protein synthesis to consumption of an EAC solution immediately before resistance exercise is greater than that when the solution is consumed after exercise, primarily because of an increase in muscle protein synthesis as a result of increased delivery of amino acids to the leg.
In one study, the consumption of six grams of amino acids plus 35 grams of sucrose consumed one hour post-exercise and three hours post-exercise made little difference because the same positive net protein balance resulted at both times (Rasmussen et al. 2000). A comparison of the two studies indicated that the response of net muscle protein balance was greatest when the carbohydrate-amino acid mixture was consumed immediately before exercise.
A study by Borsheim indicated that essential amino acid ingestion after exercise increased net muscle protein balance while non-essential amino acids were not needed to increase balance. Borsheim also indicated that there is a dose dependent response to essential amino acid ingestion (there may be a point of essential amino acid availability above which no further stimulation occurs). Additional support for this concept comes from the fact that net muscle protein synthesis was similar when 20 grams and 40 grams of essential amino acids were ingested after resistance exercise (Tipton et al. 1999). The response of net muscle protein synthesis to the drink ingested two hours after exercise was comparable to the drink consumed one hour after exercise.
In another study conducted by Tipton and colleagues, they evaluated the effects of casein and whey protein ingestion on protein balance after resistance training. Twenty-three subjects consumed one of three drinks, one hour after a bout of leg extensions. Subjects consumed the placebo, 20 grams of casein protein, or 20 grams of whey protein. The results indicated that ingestion of whey or casein protein after resistance exercise increases net muscle protein synthesis.
In a review by Rennie and colleagues, they concluded that increasing amino acid concentrations by intravenous infusion, meal feeding, or the ingestion of free amino acids increases muscle protein synthesis. They also concluded that in the post-exercise period increased availability of amino acids enhances protein synthesis.
In a recent study, Miller et al. compared the independent and combined effects of a balanced mixture of amino acids (EAAs + NEAAs) and carbohydrates on muscle protein synthesis after resistance exercise. Adding 35 grams of carbohydrate to six grams of mixed AA did not cause a greater stimulation of net muscle protein synthesis than the AAs alone. From these results, it is clear that the stimulation of protein synthesis by EAAs is not a caloric effect. The ingestion of an additional three grams of EAA (difference in EAA content between mixed AA and EAA groups) caused a much larger effect than adding 35 grams of carbohydrate to the amino acid mixture, and 35 grams of carbohydrate alone had a minimal effect.
Esmarck et al. reported that a protein-carbohydrate-fat supplement was effective in stimulating muscle protein gain over a period of resistance training in elderly men but only when ingested immediately after as opposed to two hours after exercise. Levenhagen et al. found a greater stimulation of net muscle protein synthesis when a protein-carbohydrate-fat supplement was given immediately after aerobic exercise than when it was given two hours later.
Protein Timing: My Thoughts
Protein consumption (non limiting protein) immediately before or following the workout has shown positive results regarding muscle protein balance. The question is which one is better. The study that compared before and after showed better results when consumed before. But does this make a significant difference if we consider all of the other protein meals throughout the day?
My point is that this study compared two meals but didn’t look at other meals throughout the day. These other meals have an additive effect on net protein balance (the study was also done in a fasted state, and generally this would only occur if the workout was done first thing in the morning).
I often recommend consuming a protein shake or meal before and after (within one hour after workout) the training session. If you are consuming a mixed protein meal, I suggest eating it 90 minutes to two hours before the session (consume minimal amounts of saturated fat and fiber in this meal as it slows gastric emptying). If consuming a shake before training, I recommend drinking a whey protein shake about 15–20 minutes before training. Ingesting any high quality protein will probably be efficient post-workout.
If you will not be eating again for a long time after the post-workout meal, a slow acting protein might be better (casein or mixed protein meal). The pre- or post-workout meal plays an important role in protein gains, but it is the overall effect of what you do throughout the entire day that will probably have the biggest impact on net protein balance.