Posted by Dr. Robert Portman on 9/5/2018
Most of the muscle adaptations that increase strength and endurance occur in the interval following moderate to intense exercise. Central to these adaptations is the repair and rebuilding of muscle protein. Although your muscles have multiple mechanisms to activate muscle protein synthesis the central mechanism involves a protein called mTOR. mTOR is a critical cellular switch that activates the cellular machinery responsible for repairing and building new muscle mass.
Posted by Dr. Robert Portman on 8/30/2018
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Performance Tip Of The Week
Most endurance athletes are familiar with cortisol, a catabolic hormone. In other words, it breaks down muscle tissue. Cortisol has a pretty bad image, especially among the endurance athletes. Yet it plays a vital role in helping athletes perform.
Posted by Dr. Robert Portman on 8/21/2018
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Performance Tip Of The Week
One of the more controversial nutrition questions is the amount of protein that should be consumed daily? According to the recommended daily allowance, protein intake should be about 0.36 g/lb of body weight. That means a 150-lb person should consume 54 grams of protein per day as shown in the Table below. The problem with the government allowance is the nutritionists who developed it were using sedentary adults as their models. Furthermore, the government recommendation is based on the fact that this level would maintain zero nitrogen balance, which means you would neither gain nor lose protein.
Posted by Dr. Robert Portman on 8/13/2018
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Performance Tip Of The Week
You cannot overestimate the critical importance that timing plays in post-exercise muscle recovery. Immediately after exercise, the cellular processes responsible for replenishing depleted glycogen stores and rebuilding and repairing muscle protein are activated. Providing the right combination of nutrients during this period of cellular activation has a dramatic effect on the completeness of the recovery process. The graph below illustrates this fact. The data is a compilation of multiple studies in which investigators measured the impact of delay on glycogen replenishment as well as repair and rebuilding of muscle protein.
Posted by Dr. Robert Portman on 8/7/2018
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Performance Tip Of The Week
A recent study showing that artificial sweeteners may impact diabetes has generated a great deal of media attention. Beverages sweetened with aspartame dominate the beverage category. Many people consume them because they want to reduce or eliminate their consumption of sugar. The researchers found that artificial sweeteners interfere with normal energy metabolism in a manner similar to that seen with diabetes. Laboratory animals fed artificial sweeteners, showed an increase in blood amino acid levels indicative of a greater breakdown of muscle protein for energy.
Posted by Dr. Robert Portman on 8/3/2018
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Performance Tip Of The Week
Of the 21 amino acids, leucine has a special place in endurance exercise. Although amino acids are the building blocks of protein, leucine, in its free state, has a major impact on endurance as well as muscle recovery. Leucine belongs to a class called branched chain amino acids (BCAAs), which compose about one-third of muscle protein. At one time, researchers believed that carbohydrate and fat were the only sources of muscle energy. In the mid 80’s it was discovered that when exercise exceeds 40 minutes BCCAs become an important fuel source supplying up to 20% of muscle energy needs. Even among the three BCCAs, leucine has a special role in this regard being far more readily converted to energy than the other two.
