Nutrient Timing: The Window of Opportunity

Many of us have heard about the "window of opportunity" in regards to nutrient intake and exercise. I recently attended the Northwest Personal Training Forum in Vancouver, WA, where Dr. Len Kravitz Ph.D. from the University of New Mexico helped to demystify this topic. This is what I learned:

Nutrient Timing: Delivering the right nutrient mixture at the right time to enhance recovery from exercise and improve muscle growth, strength, and power.

Nutrient Activation: The proportion and type of nutrients (fat, CHO, protein) effects the goals you wish to attain. For example, high-glycemic CHO (carbohydrate) following exercise stimulates insulin which stimulates protein synthesis. The effectiveness of any protein is largely dependent on WHEN you take it.

I am going to try and briefly explain this without getting into all the "nitty-gritty" scientific jargon...

Insulin (the anabolic regulator of muscle) has many different functions in the human body. When pertaining to fat synthesis and muscle development it is essential to understand how insulin works, in order to manipulate its functions in your favor.

Insulin is the "fat storing" hormone, and is more active in this function in people who are sedentary, but muscle cells are very sensitive to insulin after exercise. Following exercise, insulin will help increase the synthesis of muscle proteins, and increase blood flow to exercising muscle.


How does this effect you and your goals?

Goal: Exercise to Lose Fat

-Insulin is the strongest inhibitor to lipolysis ("fat burning"). When exercising to lose fat, one needs to participate in aerobic activity at a moderate intensity for a prolonged period of time. During this type of exercise, the need for fat is high, so insulin levels will be low. If you consume high-glycemic index foods prior to this exercise, this will spike your insulin levels, and inhibit "fat burning." Consume low-glycemic index foods prior to exercise and avoid high-glycemic index foods 2 hours prior to cardiovascular training.

Goal: Exercise to Gain Muscle

-Insulin promotes protein synthesis, this means you need insulin to build muscle. So when exercising to build muscle, consume high-glycemic index food 30minutes prior to weight lifting to increase your insulin levels.

- The "window of opportunity" is the 45 minute window following your weight lifting, which is the most important nutrient opportunity for muscle. Consume a CHO, protein, electrolyte, antioxidant "cocktail" following your exercise to replenish lost glycogen stores, and promote protein synthesis.


Glycemic Index - http://en.wikipedia.org/wiki/Glycemic_index

References: http://www.drlenkravitz.com/Articles/nutrientDLK.html

http://www.drlenkravitz.com/Articles/glycemicDLK.html