FIELD OF THE INVENTION

The present invention generally relates to compositions and methods for supporting exercise performance or activities of daily living. The compositions described herein are pharmaceutical or nutritional compositions suitable for enhancing exercise performance. The compositions are based on a specially formulated mixture of essential amino acids (EAAs) with additional components. The compositions target support of muscle protein synthesis and reduction of muscle breakdown during exercise, increasing muscle blood flow during exercise, decreasing the perception of fatigue by supporting optimal availability of neurotransmitter precursors, providing energy for rapids bursts of exertion during exercise, and maintaining adequate electrolyte balance during exercise.

BACKGROUND OF THE INVENTION

Muscle protein is in a constant state of turnover, meaning muscle protein is being broken down and synthesized continuously. Exercise workouts are undertaken to improve muscle performance. Regardless of the nature of the exercise workout, the principle physiological mechanism underlying improvements in muscle function and muscle size is the balance between muscle protein synthesis and muscle protein breakdown. Exercise causes an increase in blood flow to the muscle, which in essence “flushes out” intracellular essential amino acids (EAAs) into the blood. When concentrations of EAAs inside the muscle cells are lowered, the rate of muscle protein breakdown is increased. In addition, intracellular EAAs serve as precursors for the synthesis of new muscle protein. As the muscle EAAs are flushed from the intracellular fluid to the blood, there are fewer EAAs available for reincorporation into muscle protein via protein synthesis. The impaired ability of muscle protein synthesis to keep pace with muscle protein breakdown during exercise is also due to an increased oxidation of certain (but not all) EAAs. Some of the EAAs released in the process of muscle protein breakdown are oxidized to produce the energy needed to support muscle contraction. Once EAAs are oxidized, they are not available to be reincorporated into muscle protein.

Leucine is the most abundant EAA in muscle and also can play a role as a “nutraceutical”, meaning that in addition to its role as a precursor for protein synthesis it also serves as a signal to the molecular mechanisms in muscle cells that are involved in the initiation of protein synthesis. Consequently, leucine availability can become rate limiting in terms of the synthesis of muscle protein during exercise. For example, even just light exercise causes a 4-fold increase in leucine oxidation, while the oxidation of other EAAs such as lysine and phenylalanine do not increase. The disparate rate of oxidation of different EAAs reduces leucine concentration in blood, creating an imbalance in EAA concentrations in the blood. Leucine depletion in the blood during exercise not only decreases synthesis of new muscle proteins, but also induces the perception of fatigue. Tryptophan, the precursor to serotonin, and leucine are structurally similar and compete for the same transporter for entry into the brain. When the blood concentration of leucine falls relative to tryptophan concentration during prolonged aerobic exercise, more tryptophan enters the brain and the amount of serotonin is increased. An increase of brain serotonin during exercise can decrease mental focus, giving the perception of fatigue even when physical capacity is not limited.

The notion that leucine can be rate limiting during exercise has led to the popularity of dietary supplements of leucine or the branched chain amino acids (BCAAs) leucine, isoleucine and valine. However, provision of these supplements has proven ineffective in stimulating muscle protein synthesis, during exercise or in any other circumstance. In addition, increased BCAA levels only slightly improve mental focus. This is because an increase in BCAAs will not only decrease tryptophan uptake by the brain, but also limit the uptake of phenylalanine. Phenylalanine is the precursor for the synthesis of dopamine, which is the principal excitatory neurotransmitter in the brain. Mental focus and alertness is the result of the balance between dopamine and serotonin in the brain. Consequently, an EAA formulation with abundant BCAAs as well as phenlyalanine will most effectively enhance mental focus during exercise. Therefore, there is a need in the art for compositions comprising a unique combination of ingredients for improving exercise performance, wherein the combination of ingredients accounts for the disparate rates of oxidation of different EAAs and promotes mental focus during exercise. Such compositions can result in an increase in muscle protein synthesis and a reduction of muscle protein breakdown during and immediately following exercise, ultimately increasing muscle mass, muscle strength, and muscle function, and can also improve exercise performance by reducing the perception of fatigue.

