anabolic window - do you need your post-workout protein ?
Anabolism refers to muscle growth (muscle protein synthesis or MPS), which is the opposite of catabolism (muscle protein breakdown or MPB).
Exercise is naturally a catabolic process, as it breaks down protein, which makes up the muscle for energy use. However, physical activity also increases muscle growth due to the increase in blood flow to the muscle as a result of exercise, which in turn increases muscle protein turnover, contributing to greater MPS. The growth process overrides muscle break down, which results in bigger, stronger muscles (MPS > MPB).
The post-exercise period is often considered important for nutrient timing, as theoretically, consuming protein within ~30min post-workout limits muscle break down caused by exercise, by repairing damaged tissue and repleting energy stores. It has also been suggested that during this time anabolic signalling (the mechanism which leads to muscle growth) is more sensitive, thereby increasing muscle mass and performance. This concept is known as anabolic window.
BUT, as it often occurs in science, theory ≠ practice. So let’s explore the research on whether anabolic window is effective in practice.
The anabolic window hypothesis assumes that exercise is carried out in a fasted state. A prolonged fasted state, such an as overnight sleep encourages muscle break down. Exercising in a fasted state further exacerbates MPB, for reasons described previously. So, in this case it would make sense to consume a combination of protein and carbohydrates to end the MPB state and encourage MPS.
However, as not everyone exercises right after waking up, it is important to consider how much protein there is in the circulation. Data shows that even minimal-to-moderate intake of essential amino acids pre-workout sustains amino acid delivery to the muscle until the post-workout period, eliminating the need for a post-workout protein re-load. So, a full meal may not be necessary to stop the catabolic state, but it is important to have some protein circulating in the system.
If the last meal was consumed 4-6h before exercise, consuming a protein-rich meal would be beneficial for muscle growth / /maintenance whether you have exercised or not. Regular protein intake throughout the day is particularly important for healthy ageing to avoid age-related sarcopenia. Keep in mind that the concept of “healthy-ageing” needs to be applied BEFORE the old age is reached for it to be effective.
Can consuming more protein than needed result in extra muscle growth? No. This is due to what’s known as the “muscle-full effect”, where despite the availability of amino acids in the circulation (protein available in the body), muscle growth is attenuated after 20-40g of protein has been consumed and any excess is oxidised and excreted.
In other words, being a wanna be body builder with no science knowledge and eating kilos of boiled chicken in one go is going to result in a lot of nitrogen (protein) down the toilet. A more efficient way of building muscle is regular consumption of 20-40g high quality protein. Whey protein has been shown to be among the highest quality of proteins.
Take-away:
Unless you workout first thing in the morning and if you eat regular meals, post-workout protein is not needed.
An easy and efficient way to stimulate post-workout muscle growth may be consuming a pre-workout containing BCAAs (branched-chain amino acids).
On a personal note, I love taking BCAAs before working out, as they contribute to my leucine intake (read on the importance of leucine for healthy ageing in previous posts on the leucine trigger). BCAAs also boost my exercise performance, as they are often mixed with caffeine sources, which is known to stimulate performance.
