First up I'll discuss a very recent article regarding carbohydrate supplementation to enhance post-workout protein synthesis, followed by one that added protein to the mix and also measured protein synthesis.
Here's a bit of background to help lay the groundwork. Net muscle protein balance is essentially protein synthesis minus protein breakdown. Diet and exercise are just two factors that play a role with this. More important than consuming protein itself, however, is the total energy (calories) intake. Consuming an adequate amount of energy is the first step; then it's time to fine tune where the energy is coming from.
One obvious source of calories that will help promote a positive protein balance is protein itself. I know, not cutting edge. Keep in mind when you hit the gym, you're actually breaking down muscle tissue (protein) rather than building it (catabolism). The end result is that during recovery, a person is generally in negative protein balance unless they optimize their nutrition during this recovery period.
There's a fine line between an optimal dose of weight training and overtraining; dietary manipulation can help reduce the negative effects of overtraining, but sometimes you can only do so much. Subsequently, it's important to consider the optimal time to feed the body and more importantly feed the body what it needs.
While going to the nearest fast food restaurant after a grueling leg workout may be appealing, it's not going to put you on your way to achieving your physique goals. Instead, you need to concentrate on getting in some quality nutrients as soon as possible after your workout.
The easiest way to do this is through some type of post-workout drink; a product that provides both carbohydrates and protein, but is low in fat since that slows digestion. The goal with post-workout nutrition is to shuttle the nutrients into your muscles ASAP, helping reduce catabolism.
Post-workout (and pre-workout) nutrition has been a hot topic in laboratories across the country as of late and I'll continue to report on this important topic as it continues to develop.
The goal of this study was to assess whether ingestion of carbohydrate during recovery from resistance exercise had any effect on net protein balance. A number of recent studies from this group and others have shown that oral administration or infusion of just 6 grams of essential amino acids (EAA) positively effected protein synthesis (remember, you want synthesis to be greater than degradation to maintain a positive nitrogen balance).
However, the effect of these EAA was surprisingly not enhanced with a carbohydrate supplement, which increases insulin release, subsequently shuttling nutrients into the "hungry" muscle cells. Therefore, this peaked the curiosity of the researchers and they were determined to see if the carbohydrates alone had any impact on protein synthesis.
Sixteen otherwise healthy male and female subjects participated in the study. The subjects were divided into two groups (8 subjects per group) and randomly assigned to either a 100 g carbohydrate drink or a noncaloric placebo drink (this is done so subjects don't know which group they are in and if they are receiving the actual supplement).
A placebo is essentially a non-nutritive pill or drink. By having a placebo group, the subjects are "blinded" as to what they're actually consuming (to avoid the "placebo effect" which is when you feel you are taking something, so therefore perform better, when really you are taking nothing useful). I digress.
One week prior to the start of the actual protocol, subjects were first familiarized with the exercise protocol and measured their 1 repetition maximum (RM)-the maximum amount of weight that can be lifted one time for a particular exercise.
The protocol then called for them to perform a resistance exercise bout consisting of 10 sets of 8 repetitions of leg presses at 80% of subjects' predetermined 1-RM (i.e., it wasn't very fun). After the workout, subjects were instructed to rest in bed for 4-hours. While resting, both the carbohydrate group and placebo group received their drinks 60-minutes post-workout.
Without putting you to sleep with the excruciating details of how they measured protein synthesis, suffice it to say they did it and did it well. Turns out the group supplementing with the carbohydrate drink had a significant increase in insulin levels vs. the placebo group (not surprising).
In addition, net muscle protein balance improved in the carbohydrate group, whereas it remained unchanged in the placebo group. Huh, looks like we can throw those protein supplements out the window, right? Well, not so fast. While the carbohydrate group did improve over the placebo group, the results were not close to as impressive as some previous studies using both carbohydrates and protein combined.
However, if you're in a bind and don't have protein at hand, getting in some carbohydrate - try not to make it soda, as I've amazingly seen people do - immediately after a workout is better than nothing at all.
As I mentioned earlier, one effect of carbohydrates is to increase insulin release in the body. Insulin is the mother of all hormones and acts as a shuttle to put nutrients where they belong (and sometimes where they don't belong, like fat cells).
Therefore, if the "shuttle" is turned on from the carbohydrates, and the protein is available to be shuttled, we kill two birds with one stone-get those nutrients where they need to go as quickly as possible so you can slow or hopefully prevent catabolism and keep on growing!
2004 Journal of Applied Physiology 96:674-678
Borsheim E, Cree MG, Tipton KD, Elliott TA, Aarsland A, and Wolfe RR