Taken directly from the book Nutrient Timing: The Future of Sports Nutrition by John Ivy, PhD. and Robert Portman, PhD.
NTS (Nutrient Timing System) ENERGY PHASE (preworkout)
1. Increase Nutrient Delivery to Muscles and Spare Muscle Glycogen and Protein
Although glycogen depletion has traditionally been the concern of endurance athletes, it is also an important issue for strength athletes. Muscle glycogen levels following multiple sets can be reduced as much as 40%. Doubling the intensity of the workout doubles the breakdown.
ATP and creatine phosphate provide most of the energy for muslce contraction, but glycolysis still plays an important role. Between sets, muscle cells use the glycolytic pathway to regenerate ATP. By consuming a carbohydrate or carbohydrate/protein sports drink during your workout, you can preserve muscle glycogen and remain strong throughout your workout.
Haff and colleagues studied the effect of carb supplementation during resistance exercise. They found that when the carb supplements were provided, the decline in muscle glycogen was 50% less and that subjects could perform more work than subjects receiving flavored water.
The latest research now shows that the addition of protein to a carb supplement during resistance exercise offers further advantages in terms of preserving muslce protein, increasing protein synthesis, and even extending endurance.
Druing extended exercise, amino acids--principally the BCAAs: leucine, isoleucine, and v****e--may supply up to 15% of the muscles' energy needs. The use of some BCAAs for energy can be increased by as much as 500%, depending on the intensity and duration of the exercise. The addition of protein to a carb supplement promotes the metabolism of the ingested protein and lessens the demand for amino acid release from the muscles.
Recent studies coming out of the University of Texas Health Science Center in Galveston suggest that when protein is added to a carb supplement and provided at the beginning of exercise, there is even an increase in protein synthesis after exercise.
Finally, the addition of protein to a carb supplement has been shown to extend muscular endurance. Researchers from the University of Texas in Austin found that a carb/protein drink improved endurance 57% compared with water and 24% compared with a carb/electrolyte drink. The improvement in endurance was thought to be due to a sparing of muscle glycogen and possibly to the preferential metabolism of the ingested protein.
2. Limit Immune System Suppresion
A second objective of the NTS during the Energy Phase is limiting immune system suppresion. During moderate intensity exercise, immune function is heightened, increasing resistance to infection. However, as discussed, with strenuous exercise, the immune system is suppressed, and the risk of infection is thereby increased.
The immune system is closely linked to the neuroendocrince system, which controls the release of hormones. During strenuous and sustained exercise, this system is activated, causing the release of cortisol. Most of the immunosuppressive responses caused by intense exercise correlate with increases in blood cortisol levels. Cortisol lowers the concentration and activities of many of the important immune cells that fight infection.
Interestingly, blood cortisol levels can be regulated to a significant degree during exercise by controlling glucose availability. Bishop and colleagues showed that when athletes were given a 6% carb solution during exercise, cortisol levels dropped by almost 80% compared with subjects receiving water.
Because of the high correlation between cortisol and immune system suppression, it is logical that carb supplementation would limit the suppressive effects of exercise on the immune system. In fact, this has been confirmed, most notably by David Nieman and colleagues at Appalachian State University. These researchers have compared a number of immune system parameters during exercise with and without carb supplementation. They found that subjects receiving carb supplementation during intense exercise had lower blood cortisol levels and limited immune suppression--as indicated by a lessened T cell and NK cell reduction--compared with subjects receiving placebo.
Carb supplementation provided dual benefit during exercise...maintaining blood glucose helps maintain immune function while decreasing cortisol levels.
During resistance exercise, cortisol levels can increase fivefold. Strength athletes who ignore the benefits of nutrient supplementation during their workouts place themselves at a greater risk of experiencing the immune-suppressive effects of cortisol, which include a transient weakening of the body's major mechanisms of fighting infection.
It is also important to note...that strength athletes who severely restrict their daily carb intake may be more susceptible to infection.
3. Minimize Muscle Damage
The third important objective of Nutrient Timing during the Energy Phase is to reduce muscle damage. This damage is beneficial to a degree because it stimulates the remodeling process, which leads to larger and stronger muscles. However, the damage to the muscles must be repaired before the remodeling process can begin. Because there is no single cause of exercise-related muscle damage, nutritional intervention must address all the causes.
Carb supplementation during exercise reduces the rise in cortisol and decreases specific agents responsible for producing inflammation. Bishop and colleagues from Longborough University in England showed that carb supplementation could reduce biochemical markers of inflammation by almost 50%.
Supplementation with the antioxidant vitamin E and C and BCAAs may also help minimize muscle damage. While there does not appear to be a performance benefit from vitamins C and E, Rokitzki and colleagues found that supplementation with these antioxidants decreased levels of CPK, and important marker of muscle damage, twenty-four hours after a marathon. This finding suggests that they may limit tissue damage due to free radicals. Dr. William Evans from the University of Arkansas, a leader in this area, has suggested that antioxidants may be of benefit in the body's overall response and adaptation to exercise.
4. Set the Nutritional Stage for a Faster Recovery Following Your Workout
An important tenet of the NTS is nutritional intervention at all stages in the muscle's growth cycle. Increase muscle mass comes from a cycle of muscle stimulation, muscle breakdown, and muscle rebuilding. Every athlete knows the expression, No pain, no gain. This is true in the sense that you must train hard enough to cause a degree of muscle tissue disruption. However, training hard without appropriate nutrition intervention results in a more prolonged recovery and ultimately a weaker training response.
Although you cannot entirely prevent muscle damage and depletion of your energy stores during resistance exercise, by applying the principles of NTS you can minimize these effects, setting the stage for faster recovery.
As seen above, there is increased muscle protein degredation, in part to help supply muscle energy needs during exercise. Consuming protein during exercise will enable you to utilize the ingested protein and thereby decrease protein degredation and spare muscle protein. The same principle holds true with regard to muscle glycogen. Consuming carb during resistance exercise results in less depletion of glycogen stores.
The replenishment of muscle glycogen stores is an essentail cellular function that is given a metabolic priority by the muscles' anabolic machinery following exercise. The faster this process occurs, the quicker the muscle machinery can be reoriented toward the remodeling of your muscle fibers. The replenishment of your energy stores occurs much faster if you have limited their depletion during your workout by supplementing appropriately.
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