Understanding Local Muscle Endurance
Learn The True Cause Of Local Muscle Fatigue & Start Making Measurable Performance Improvements.
Understanding Local Muscle Endurance
Local muscle endurance is a commonly cited exercise limiter among Crossfit athletes. However, the cause of local muscle fatigue is poorly understood, and training interventions intended to improve local muscle endurance have mixed results.
One of the primary causes of local muscle fatigue is a restriction of muscle blood flow due to high intramuscular mechanical pressure. Under ordinary circumstances, there are two different mechanisms by which muscle blood flow increases. During muscle contraction, muscle blood flow is diminished, and during muscle relaxation, blood flow increases. This process is known as active hyperemia, and it regulates blood flow on a contraction-by-contraction basis.
Across many muscle contractions, there is another process called auto-regulation that increases blood flow in response to muscle deoxygenation. Interestingly, the NNOXX One wearable clues athletes into this process by monitoring both muscle oxygenation (SmO2) and nitric oxide (NO), the latter of which regulates local muscle blood flow and oxygen delivery.
The combined effects of active and reactive hyperemia determine the net change in blood flow during exercise. Only NNOXX can clue athlete’s into these processes by measuring nitric oxide, the primary regulator of muscle blood flow.
Both of the processes mentioned above occur simultaneously, and their combined effects determine the net change in blood flow from moment to moment.
However, there are cases where both of these responses are blunted, thus decreasing muscle blood flow and oxygen availability. For example, when individuals employ high threshold movement strategies, contract their muscles with excessive force, or have elongated muscle relaxation times, they will impede muscle blood flow, quickly leading to local muscle fatigue limitations and an inability to sustain work output.
Learn More!
To learn more about the causes of local muscle fatigue in Crossfit and how you can train to improve you can check out my full-length article titled, A Guide To Improving Muscle Endurance In Crossfit.
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