Last week in my introduction to this Anabolic Window Series we discussed some of the common beliefs behind post-workout nutrition. We talked about the misconception of how fast protein needs to get into your system post-workout, how casein and whey had very similar effects on muscle-protein synthesis post-workout despite the very different patterns of blood amino acid responses and talked about how unless you have a lactose intolerance whey protein concentrate is your best bet for whey protein in any scenario. This week as promised we will look at plenty of research relating to the supposed anabolic window and get that much closer to making a determination if there is such a thing or not.
Since we’ve already established that how fast protein is absorbed post-workout doesn’t make much of a difference, if at all, the next thing to look at is does it matter how soon after your workout is done you get your nutrients in? Pitkanen et al., 2003 (2) looked at free amino acid concentrations and protein synthesis and breakdown in subjects post-resistance training in a fasted state compared to a control group who did no exercise. The results may shock you. They found there was no difference in muscle-protein synthesis or muscle-protein breakdown between the groups 60 minutes after completing exercise. At 195 minutes, however, the net protein balance was worse. As they concluded, in fasting conditions, protein net balance is negative and resistance training induces an increase in muscle-protein synthesis and breakdown at 195 minutes but not yet at 60 minutes of recovery. Did you catch that? At 60 minutes post-workout there was not an increase in muscle-protein synthesis or breakdown observed.
Rasmussen et al. (3) showed that subjects who took a mixture of whey protein and carbohydrates post-workout at either 1 hour or 3 hours post-workout had no significant difference in muscle-protein synthesis. So while the essential amino acid drink did promote anabolism, the timing of ingestion in relation to the time after exercise did not matter. I want to make sure you caught that. There was no difference in muscle-protein synthesis post-workout whether nutrients were consumed 1 hour or 3 hours post-workout. So much for the idea you need to slam that protein shake as soon as your last set is done.
While post-workout nutrition has been said to be extremely important, pre-workout nutrition is also considered important if for no other reason than to make sure you are properly fueled for your workout. But what about when it comes to muscle-protein synthesis? Tipton et al. 2001 (4) looked at the difference between taking an essential amino acid-carbohydrate supplement before exercise or after exercise to determine which method had a greater anabolic response. Amino acid delivery to the leg was increased during exercise and remained elevated for 2 hours after exercise in both trials. However, amino acid delivery was significantly greater in the pre-workout trial than it was in the post trial during exercise and as well in the 1st hour after exercise. The results of this study led them to believe the response of net muscle-protein synthesis to consumption of EAC’s immediately before resistance training is greater than when taking it after exercise. One could argue based on this research that pre-workout nutrition may be even more important than the supposed post-workout anabolic window. This is something we will look at this closer next week.
For now I’d like to point out there is certainly plenty of research available showing increases in muscle-protein synthesis and hypertrophy from post-workout nutrition, but the problem with most of them is those studies tend to use pre and post-workout supplementation, so there is no way of knowing if it was one, the other, or both that made the difference. (5,6,7,8) You can also find plenty of conflicting reports such as Esmarck et al. (9) which showed elderly subjects had a greater increase in muscle growth by supplementing with protein right after training when compared to 2 hours after training whereas Verdijk et al. (10) showed no difference in muscle mass from consuming a post-workout protein supplement in elderly men. The other thing to keep in mind when using elderly subjects is they not only digest protein different from younger healthy adults but they have also been show to benefit from having most of their protein intake for the day in one sitting (11). The other question that comes into play with the studies that use protein ingestion before and after workouts that showed better results is; were the results because of the timing of the protein in relation to the exercise, or was it because subjects now had a higher daily protein intake than before?
In what might be the best news yet for protein synthesis was a study done by Tipton et al., 2003 (12) that took 7 subjects who participated in 2 different studies. In one study they rested and in the other study they rested plus did resistance training and took an essential amino acid drink. They found that responsiveness of protein synthesis was enhanced for a full 24 hour period after resistance training. That’s one heck of an anabolic window! This research backs up what MacDougall et al., 1995 (13) showed which also showed muscle-protein synthesis to be elevated for 24 hours post-workout. Some research such as work by Phillips et al., 1997 (14) even shows that protein synthesis can be elevated for up to 48 hours post-workout.
As much as it sounds like I’m ready to put the final nail in the coffin for the anabolic window, I’m not ready to do that quite yet. There is more research I would like to present next week which could give some good news, or bad news depending on how you look at it, for the anabolic window. Next week I will follow-up on the pre vs. post-workout differences as promised earlier, take a look at some comparisons of milk vs. supplements post-workout, and try to put the final wrap on this by giving you my personal conclusions of it all. I sure hope you will join me!