How important is Protein Timing? A New Meta-Data Analysis
Protein timing is considered an important aspect of building fitness and strength by professional and amateur athletes.
The term ‘protein timing’ basically refers to identifying key times in which to consume high protein foods. This is used to encourage faster muscle development, plus to supply the body with nutrients to rebuild, repair and replenish muscles after workouts. It’s a particularly common practice among bodybuilders and other athletes that rely on muscle mass.
Over the years there has been considerable debate surrounding the efficiency of protein timing. Fortifying normal diets with supplements, amino acids and protein powders has always attracted criticism. However, there has been a general agreement within the scientific community that the composition and timing of protein consumption is particularly important in relation to the recovery process following exercise. The practice advocates the consumption of carbs and proteins within an hour of a workout to maximise muscle nourishment.
A new meta-data study analysis published in volume 10 of the 2013 edition of Journal of the International Society of Sports Nutrition raises serious questions surrounding the validity of protein timing. While there have been many studies published that demonstrate an “anabolic window of opportunity”, Schoenfeld and colleagues have questioned the accuracy of these results in their meta-analysis.
Although the concept of increasing nutritional supply after exercise to refuel the body makes logical sense, there have been critical flaws identified in studies testing this theory. Schoenfeld and his co-authors found a significant disparity in long-term research throughout their literature review. Some studies showed no major changes, while others revealed clear muscular adaptations.
There are several constraints with long-term studies that make it difficult to get statistically accurate results. Due to the costs involved in such research, the study sample size is typically small. With few participants, it isn’t possible to generate results that can be statistically significant. However, a meta-data analysis compiling all the results from different studies can provide a valid quantative analysis and greater statistical meaning.
Analysing The Research
During the meta-data analysis Schoenfeld and colleagues meticulously assessed data using different methodology to ensure accuracy. Initial results from a simple pooled analysis showed no increase in strength as a result of protein timing, although a small but significant effect was noted in respect to muscle hypertrophy. However, this analysis wasn’t detailed enough to confirm the presence of an anabolic window.
Schoenfeld and his co-authors then completed a sophisticated regression analysis to independently evaluate each variable and how these variables impacted the results. They found that the quantity of protein consumed determined the variance in results across virtually all studies examined in the meta-data analysis.
The majority of studies failed to match the protein intake between subjects and controls. The experimental groups were found to have consumed substantially more protein compared with the control groups. This meant that the average protein intake within control groups was not sufficient to maximize protein synthesis connected with resistance training. In a few studies where protein intake was matched between the control group and the study group, Schoenfeld and colleagues found no significant impact as a result of protein timing.
Following the meta-data analysis, Schoenfeld and his co-authors concluded that protein timing appears to be irrelevant. Whether protein is consumed immediately after training or a couple of hours later does not seem to make a significant difference. The ‘anabolic window of opportunity’ appears to be absent.
Meta-data Analysis Limitations
However, Schoenfeld and colleagues did acknowledge that their criterion for protein timing was less than an hour pre- or post-workout, and non-timed consumption was greater than 2 hours. They did not analyse if waiting for five hours or longer to consume protein after a training session would have a negative impact. The authors believe that an ‘anabolic window of opportunity’ probably does exist. However, it is likely to be much wider at around four to six hours and will partly depend on when the pre-workout meal is consumed.
Another limitation in the meta-data analysis was a restricted number of studies that had matched protein consumption between untimed and timed groups. A lack of statistical power means that it isn’t possible to rule out underlying effects that couldn’t be detected in this analysis. Also, the studies focused largely on untrained subjects and not elite athletes or bodybuilders. How the body reacts and the training capacity is very different between these groups. Thus, it’s possible that protein timing may be more important for trained subjects.
The work by Schoenfeld and colleagues suggests that protein timing may not be as crucial as once thought. However, the analysis also had its own limitations and there is certainly room for further research. This meta-data analysis has done the groundwork to direct future studies to achieve a better insight into the significance of protein timing.