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Post-Exercise Metabolic Window

The golden opportunity for muscle growth

Maximizing muscle and glycogen synthesis

The Golden Hour

The Metabolic Window - Post-Exercise

  • A metabolic opportunity exists immediately post-exercise that can have a great impact on training success.
  • Whether you are involved in endurance sports or are trying to increase muscle mass, by not understanding this metabolic change, you risk missing out on taking advantage of a profound anabolic potential in this early post-exercise stage.
  • Between 15 minutes and 45 minutes, there is a 600% increase in glucose uptake and protein synthesis! 32
  • You have between 15 minutes to 45 minutes post-exercise to influence protein synthesis and glycogen storage. Beyond 1 hour, you will have lost this potential and at 2 hours, the insulin receptors become insulin resistant and at this point, there is a
    negative net protein balance change32.
  • Thus without nutritional support in this immediate post-exercise period, you can actually lose muscle mass16.

The high cost of delaying nutrient supplementation post-exercise

  • As mentioned above, the greatest opportunity lies between 15 minutes and 45 minutes to take advantage of the anabolic window post-exercise.
  • You need to take advantage of the exquisite insulin receptor sensitivity that occurs post-exercise. Once insulin resistance sets in at around 2 hours, you have the potential for net muscle mass loss16,32.
  • All that hard work in the gym absolutely lost because optimal nutrition has once again been underestimated for its potential to stimulate an anabolic state in terms of glycogen and protein synthesis.
  • The great cost of nutrient delay is shown in the graph below

How does post-exercise supplementation work?

  • Post-exercise supplementation increases insulin either via a glucose polymer or insulin or both.
  • What many people do not realize is that protein itself is a powerful stimulator of insulin this makes sense if you realize that insulin also stimulates transport of amino acids into cells for protein synthesis. Whey Protein Isolate [WPI] in particular is a powerful stimulator of insulin and is an important component of the post-exercise supplementation protocol.
  • Insulin is normally seen as the 'bad guy' and essentially, you need to control your insulin responses in day-to-day eating to prevent many chronic illnesses such as diabetes and weight gain. However, in the post-exercise period, insulin is your friend and can help you increase muscle mass and replenish glycogen stores rapidly.
  • Insulin will help to increase glucose transport into cells by 600% as shown above and to increase amino acid transport into muscle cells by 50% and to also stimulate the production of the enzymes responsible for protein synthesis by as much as 67%32

Insulin suppresses the powerful catabolic hormome cortisol post-exercise

  • Cortisol is a stress hormone released when your body is fighting an infection or if you are starving or after strenuous exercise.
  • Cortisol is your enemy post-exercise
  • Cortisol has an antagonistic effect to insulin and does things opposite to what insulin does. Cortisol draws amino acids such as glutamine and alanine away from muscles so that they can be converted into glucose during intense exercise. Glycogen stores can also be raided in the liver to release glucose.
  • Remember, your brain depends on glucose to function and the brain has to be supplied at all costs even if this means the loss of muscle mass. Glycogen stores that normally keep the blood glucose levels optimal during exercise, can diminish rapidly during intense exercise and may in fact be depleted within 90 minutes. As glycogen stores diminish, cortisol [along with epinephrine (adrenaline) and norepinephrine (noradrenaline)] will increase to ensure an adequate supply of nutrients for brain and cellular functions.
  • It is important to understand that exercise is a catabolic process resulting in tissue breakdown.
  • To begin the anabolic process after exercise, you must put an end to this tissue breakdown process immediately after exercise. The Golden Hour supplementation strategy outlined in NutriDesk and based on important work by Dr John Ivy from Texas University, offers strategies depending on whether your exercise routine is likely to completely deplete glycogen or not.
  • The post-exercise supplementation is designed to help increase insulin levels substantially and to help the recovery process and to stimulate protein synthesis independently of insulin levels. 

Link to Exercise Topic References

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The Performance Zone

Dr John Ivy