Most gyms now stock protein shakes and bars for a post-workout fix. Here in the UK even our petrol stations now boast an array of protein balls, bars and shakes. But do you really need this protein straight after your workout, or is it just a cheeky way of selling you more stuff?
The answer depends largely on the type of workout you’ve just done. If the session took you into full overload, either with cardio or weights (ie a super hard workout that might be above and beyond a usual session) then the answer is yes. HIIT, high volume strength training (anything over 3 sets per muscle group) insanity or a hardcore circuit would be an example of a workout which will benefit from a post protein fix. On the other hand, a steady more habitual workout will not cause the need for a quick protein fix afterwards.
One often overlooked factor is carbohydrate. In training we are breaking down muscle fibres, which then adapt larger and stronger in recovery. Protein is the building block of muscle, so will help this process. But the body runs primarily on glycogen, or blood sugar. This will be severely depleted after an intense workout, so needs to be replaced to aid the adaptation process – getting fitter. The food most easily turned into glycogen is carbohydrate. So in fact the perfect post-workout meal would be a combination of the two. Incidentally, this is why milk is sometimes promoted as a great post workout drink – it contains both protein and carbohydrate.
Immediately after training there is a window of opportunity where the metabolic rate and release enzymes that help the body pull carbohydrate into the muscles and liver are highest. So for those 15-30 minutes energy taken in will be used to replenish and repair, with little needed for fat storage. Eat outside of that recovery window and the benefits are reduced. In addition, starving the body of carbohydrate after a workout places it in a stressful situation; this stress will diminish the gains of your session.
Front loading the session with protein will also be beneficial – the body can only take in and properly assimilate around 20g of protein at once. This is why most protein shakes are in 20g doses. So 20g an hour before and then 20g straight after would be the ideal intake; as above be sure to include some healthy, fibre filled carbohydrate too, like sweet potato or brown rice.
The International Society of Sports Nutrition in the US suggests active people aim for an overall daily protein intake between 1.4–2 grams per kilo of body weight and taking in this protein in even doses every 3–4 hours. So a hard training 70kg lady would need around 70 x 1.8g of protein a day – 126g of protein.