Posted on June 24, 2015 by Jenny Cromack

Nutritional timing is an important and popular strategy used around exercise sessions, and generally involves the manipulation of carbohydrates and proteins. It has been stated that such manipulations can have dramatic effects on body composition. In fact it has even been stated that timing of nutritional content may be more important than overall daily consumption.

This is a complex topic and far exceeds the capacity of this blog, however when we look specifically the period of time post training is often considered the most important window for nutrimental timing. So should I drink a protein shake after a workout? This blog is going to look at whether or not protein consumption after a workout is beneficial if you want to develop muscle mass. Luckily, there has been an extensive amount of research examining protein consumption post exercise.

The results of theses studies are actually very conflicting which makes things confusing! Also a lot of the research has included both a pre and post workout shake, making it difficult to get to the bottom of post workout nutrition. It may be that pre or post workout is all that is required instead of both, however research is limited.

One of the first studies was completed by Esmark et al., (2001), this study involved participants following one of two protocols, consuming 10g of a combination milk/ soya protein either immediately after exercise or 2 hours post exercise. The session involved compound movements, such as the lat pull down and squat for 3 whole body sessions a week over 12 weeks. The study reported significantly greater increases in hypertrophy in the group that consumer protein immediately following training, opposed to the 2 hour group.

However more recently Verijk et al., (2009) was unable to replicate these findings, in which they established no difference in hypertrophy between groups, it is worth noting however than only 10g of casein protein was ingested post workout over the 12 weeks study. Furthermore measures of hyperhtophy were isolated to the legs, leaving us wondering… what about the rest of the body? When studies have been conducted more thoroughly such as the work of Cribb and Hayes., (2006), the positive benefits of post exercise protein consumption can be identified. They compared the ingestion of the protein shake over 2 time periods (daily protein content for calories was matched between groups):

• In the early morning and the evening
• Before and after training

Both groups consumed 1g/kg body weight of protein during each time period, furthermore both groups completed the exact same gym sessions. The researches established a significant increase in hypertrophy when protein was consumed pre and post workout, highlighting the significance of this critical window.

Moving forwards Willoughby et al., (2009) also found positive hypertrophy occurs when protein was consumed post workout, however during this study the researchers also attempted to identify any possible implications towards fat mass. So instead of comparing protein consumption to non protein consumption, the researchers compared pre, and post workout protein to pre and post workout dextrose.  After 10 weeks of 3 sets of 6-8 reps at 85-90% intensity the group that consumed protein immediately pre and post workout had, greater total body mass, greater fat free mass and greater muscle mass compared to the carbohydrate group. The only limitation of this was the fact that the protein groups consumed a total of 40g more protein than the carbohydrate group each training day, this make its difficult to say with 100% certainty that the timing was the crucial factor.

Similar to the study by Crib and Hayes., (2006), Hofmann et al., (2009) examined the same interventions of pre, post workout shakes against consuming protein shakes in the morning and evening. Interestingly in this study no significant difference was noted in the hypertrophy levels after 10 weeks of good resistance training. It is worth noting that this study unlike others used DXA scanning which is not as accurate and may not detect subtle changes compared to MRI and CT, used in the other studies.

In conusion as you can see the notion that you must consume post workout protein shakes to build muscle is very far from definitive, however you could argue there is some strong evidence to suggest its not a bad idea. Particularly when we consider no studies have demonstrated fat gain from their consumption. Despite the claims of many protein companies from guidelines on protein form, type and amount are still not clear. Studies have shown benefit from small amounts such as 10g all the way upto 1g/kg.