There is 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 look at 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 protein synthesis rates stay elevated for up to 48 hours after a heavy resistance training session. If protein-containing food or amino acids are delivered either immediately before exercise or in the postesxercsie period then the rise is greater. If an insufficient supply 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 the exercise bout when consumed pre-workout than after exercise (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. These results indicate 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 6 grams of amino acids plus 35 grams of sucrose consumed 1 hour post exercise and 3 hours post exercise made little difference because the same positive net protein balance resulted at both times ( Rasmussen et al., 2000). Comparison of the two studies mentioned above 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 are not needed to increase balance. Borsheim also indicated 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) and the response of net muscle protein synthesis to the drink ingested 2 hours after exercise was comparable to the drink consumed 1 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 1 hour after a bout of leg extensions. Subjects consumed either placebo, 20 grams of casein protein, or 20 grams of whey protein. The results indicated that ingestion of whey or casein protein after a bout of resistance exercise increases net muscle protein synthesis. In a review by Rennie and colleagues they concluded that there is no doubt that increasing amino acid concentrations by intravenous infusion, meal feeding, or 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 carbohydrate on muscle protein synthesis after resistance exercise. Addition of 35 grams of carbohydrate to 6 grams of mixed AA did not cause a greater stimulation of net muscle protein synthesis thatn the AAs alone. From these results, it is clear that stimulation of protein synthesis by EAAs is not a caloric effect, because ingestion of an additional 3 grams of EAA (difference in EAA content between mixed AA and EAA groups) caused a much larger effect than addition of 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 only when ingested immediately after, as opposed to 2 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 2 hours later.
Protein Ttiming: My Thoughts
Consumpiton of protein (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 ? What I am saying is this study was done while looking at the comparison of two meals without looking at other meals throughout the day which have an additive effect on net protein balance (the study was also done in a fasted state, generally this would only occur if workout was done first thing in the morning).
I often recommend that a protein shake or meal be consumed before and after (within one hour after workout) the training session. If you are consuming a mixed protein meal I would suggest it be eaten 90 minutes to 2 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 would recommend 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 affect of what you do through out the entire day that will probably have the biggest impact on net protein balance.
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