Few athletes do not know about the glycogen window, or at least that you should eat after a workout. However, many do not fully understand why this is important, or that nutrient timing (NT) may differ between sports, by fitness level, and even by gender. While eating something is better than nothing, optimal recovery and hence performance can be strongly influenced by recognizing what type of NT is best for for you. A recent blog explores new research regarding the impact of protein intake following training in body builders vs new trainees.
Bottom line: Regardless of training status, eating immediately after training is best for maximizing gains, particularly the greater your training history.
Why does all this matter?
Adaptation to any exercise depends on energy and raw materials. During exercise fuel stores are drained (or exhausted), muscle is damaged in different ways, and hormones are released to aid in maintaining blood glucose and ultimately energy to the brain and muscles; i.e., this is all catabolic. Following exercise, the hormone mix shifts to the restoration of fuel stores (e.g., restoring glycogen) and remodeling muscle (adapting muscle to better respond to the stress just placed on it); this is anabolic. In general, the damage and breakdown of muscle is greatest following eccentric (lengthening) contractions, like the “negatives” of weight lifting, or landing phase during running. However, fuel use, catabolic hormones, and oxidative stress all cause “damage”. This damage is the signal to adapt and hence CRITICALLY IMPORTANT to improving performance (i.e., adapting). This is a good reason to skip the NSAIDS and anti-oxidants, both of which reduce this catabolism.
Following specific types of exercise, the fuel needs differ between activities, durations, intensities, and apparently training level. In general, glycogen use is highest in endurance sports, so refueling is needed more than protein, while resistance training requires more protein than carbs. However, the combination of both has been shown to be best. As the article mentions above, timing is critical to resistance training for many possible reasons, but based on my understanding of the literature, anabolic hormone (e.g., testosterone, growth hormone) increases a very short-lived, therefore to maximize their effect you need to eat as soon as possible. Likewise, if you’re doing back to back races with less than 24 hrs recovery, glycogen repletion is maximized in the first 30-120 min.
Broad Recommendations for Refueling
Endurance: If you trained “hard” for at least 1 hr then 10-15 g of protein and 30-60 g of carbs in the first 30 min is what to aim for. Adjust total calories based on your weight goals and caloric expenditure.
Strength: Assuming you trained hard for at least 30 min and your goal is to improve muscle “tone” (really hypertrophy) and overall adaptation, 15-25 g of protein and 30- 50 g of carbs immediately after is a good place to start. If mass and weight gain are major goals, then repeat that in the first 2 hrs. You might also consider do this before training, as well. Regardless of your goals, the equivalent of a glass of milk should be consumed after training otherwise you’re likely missing some gains.
But what about fasting?
Fasting, as discussed on this blog and elsewhere is HOT. Everyone is talking about all the benefits of fasting, and even I discussed some of these. However, the research on fueling as an aid to performance is far more extensive, particularly after training. In my opinion, if you train hard consistently, even if you’re trying to lose weight, there simply is no good evidence to support NOT EATING after exercise!