There is no doubt that Paul Cribb's and Alan Hayes' amazing paper, "Effects of Supplement Timing and Resistance Exercise on Skeletal Muscle Hypertrophy1" will be quoted for years and probably decades. The questions is: Can others duplicate their results? This brings to mind the Isidori2 paper (low dose arginine and lysine ingested orally increased growth hormone 700%), which is still cited 25 years after its publication, even though numerous researchers have failed to reproduce its effects. Replication of Cribb's and Hayes' findings by others is critical since this, like most papers on ergogenic aids, was done with a small sample size.
The research was designed to determine if there were any differences in the time of day that serious weightlifters ingested nutritional supplements to promote muscle strength and size. There have been studies showing that protein and carbohydrate, either before or following exercise, are beneficial when compared to placebo in stimulating protein synthesis, muscle strength, and muscle mass. In order to test these theories, the subjects normal meal patterns are altered. For example, outside a laboratory those who lift weights for strength and size do not wait 3-5 hours after a workout to eat. Nor do they train after an overnight fast. To me, these studies simply reinforce the fact that food is required to build muscle. I'm not impressed when groups who drink a protein/carb shake after a workout make better gains than those who have zero calorie placebo, because in real life, people go and eat after workouts.
In this case, the subjects' diets were analyzed for 8 weeks prior to the study and also monitored during the study. Thus the authors could insure that the subjects did not alter their diet or meal patterns during the research. The diet analysis revealed that all subjects had a high protein intake of around 2 gm per kilogram of body weight (slightly less than 1 gm per pound, which is 2 1/2 times the RDA). In addition to protein and carbohydrate, creatine was also included in this trial.
The supplement was dosed by body weight. For an 80 kg (175 lb) subject, this equated to approximately 270 calories, 32 gm of protein, 34.4 gm of carbohydrate, 0.4 gm of fat, and 5.6 gm of creatine. It was taken twice daily on the 4 days per week the subjects worked out. One group drank the supplement in the morning and the evening, while the other group took the supplement just before and just after their workouts.
The exercise routine was mostly free-weights, which emphasized compound movements involving large muscle groups. The 3 exercises that were measured at the beginning and at the end of the 10 week (40 workout) study were bench press, squat, and dead lift. The study methods included whole body scans, muscle biopsies, diets analyzed before and during the trial, workout diaries, and workout supervision with personal trainers who were blinded to the test groupings.
Both groups experienced strength gains and the authors point out that the creatine used was clearly a factor and when subjects engage in resistance exercise programs take creatine, most notice accelerated muscle response. What was unique about this trial was that it compared the timing of creatine dosing. Prior to this study, the time of day that creatine was ingested was not considered important as long as the amount consumed raised and then maintained elevated intracellular levels. This is because creatine is not a substance (like caffeine) which is felt shortly after ingestion. Instead creatine is not noticed and will not work until it builds up. This takes a minimum of 3 days.
The group who took the supplements before and after exercise had greater increases in strength on the bench press, squat, and dead lifts than the group who took the same product in the morning and evening. They accrued more lean mass and muscle hypertrophy (greater increases of type 2A and type 2X muscle fibers diameter as well as higher levels of intramuscular contractile protein) than the AM/PM users. The pre/post group also had more muscle glycogen, total creatine and phosphocreatine (as measured by muscle biopsy). In other words, 10 weeks of the same amount of supplemental creatine, protein and carbohydrate yielded greater intracellular levels of total creatine, protein and carbohydrate when taken a few minutes before and after workouts compared to AM-PM dosing. And these findings were not due to a post praandial spike, because in week one the pre-post group did not have higher intracellular levels of creatine glycogen or contractile protein than the AM-PM group. Because we know people will quote these results for years, it will be very interesting to see if others can replicate the results of this study.