Training on an Empty Stomach
Everyone should pay particular attention to pre and post-workout fuel demands. While I do have clients (particularly those who are obese) who utilize the "cardio on an empty stomach" approach, let us realize that when glycogen levels are low or depleted, so is ATP. ATP is the source for muscular contraction for both weight training and cardio-involved activity (remember, cardio training also requires muscle fibers to contract). The primary source of contraction for aerobic work are Type 1, or "slow twitch" fibers which use primarily carbohydrate and fat to produce energy.The body may also use protein when carb and/or fat energy are not available (by breaking down its muscle tissue for energy-Not good, guys!). We all have 3 choices for meeting energy requirements.1. Using stored glycogen 2. Using stored fat 3. Using amino acids (muscle). Cardio/and or weight training in the a.m on an empty stomach eliminates number 1. Those who display a higher degree of muscular development and/or lower bodyfat levels will quickly move to number 3. After 8-10 hours with no food, liver and blood glycogen levels will be almost depleted, and performing taxing activities may speed up muscle-breakdown at an alarming rate.
For those complaining of diminished energy and a lagging workout performance, consider consuming a favorable liquid protein/amino acid source or even a low G.I. carbohydrate/favorable protein pre-workout meal, roughly 90 minutes prior to an intense weight training or cardio session. Remember, while of course we do burn calories (energy) during the activity, we DO NOT immediately lose fat. That is an end result of properly regulated exercise and a disciplined diet, and occurs subsequent to the activity and over an extended course of time-- Precisely why there is no "1 Day Physique Transformation Challenge!!" Finally, keep in mind that there are 2 distinct times when "insulin sensitivity" (nutrient uptake) is most favorable. When we get up in the morning (after a 6-10 hr. sleep period/fast), and immediately following the workout.
Just some considerations, particularly for those with diminshed energy/training concerns.
-Eric Shrieves