The lactate link to muscle fatigue

The lactate link to muscle fatigue

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  1. Muscle fatigue is not caused by lactic acid. Glycolytic pathways or the breakdown of glucose creates lactate molecules and for every molecule produced a hydrogen ion is formed. As hydrogen ions accumulate within the muscular cell the area becomes acidic. Muscle acidity reduces enzymatic reactions.

    The normal pH of a muscle is 7.1 as hydrogen ions increase the pH levels change to about 6.5. The acidic environment stimulates the nerve endings in the muscle creating the perception of pain and burning. The point of muscle fatigue is referred to by coaches and athletes as the lactate threshold (LT) or anaerobic threshold (AT).

    The accumulation of hydrogen ions may not be the only culprit in muscle fatigue. Potassium increases may also play an extensive role in muscle failure and pain. (Bangsbo J, Madsen K, Kiens B, Richter AE,1996).

    Intense exercise produces higher levels of extracellular potassium which indicates that hydrogen ions may not work independently in muscle fatigue. Intermittent training decreases the accumulation of potassium delaying exhaustion. (Nielsen JJ, Mohr M, Klarskov C, Kritensen M, Krustrup P, Joel C, Bangsbo J, 2004).

    Muscle acidity along with potassium levels influence fatigue. The pain experienced during high intensity exercise can be credited to the muscular system’s inability to shuttle the hydrogen and potassium levels out of the muscle cells resulting in acidosis.

    An individual can train specifically to accelerate the clearance of lactate molecules and hydrogen ions. Increasing lactate thresholds also improves the tolerance for increased muscle plasma acidity. The outcome of the training program focusing on increased lactate thresholds or aneorobic thresholds will result in an athlete’s ability to work longer and harder delaying the onset of fatigue.

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