The Chris and Paul Show
The biggest factors in truly killing your gains - FATIGUE
Podcast summary created with Snipd AI
Quick takeaways
- Understanding CNS fatigue is crucial for breaking through plateaus and maximizing muscle growth.
- Calcium ion-related fatigue interferes with muscle contractions, reducing force production and the ability to recruit high-threshold motor units.
- Central nervous system fatigue can be measured through voluntary activation tests, providing insights into designing effective training programs.
- Fatigue affects muscle tension and recruitment, emphasizing the need for longer rest periods and appropriate exercise selection.
Deep dives
Central Nervous System Fatigue and Motor Unit Recruitment
Central nervous system fatigue reduces motor unit recruitment, particularly in the highest threshold motor units responsible for hypertrophy. Understanding CNS fatigue is crucial for breaking through plateaus and maximizing muscle growth. It can be caused by factors such as the perception of effort and discomfort during exercise.
Calcium Ion-Related Fatigue and Mechanical Tension
Calcium ion-related fatigue occurs when there is an influx of calcium ions into muscle fibers, particularly type 2 fibers. These fibers have low mitochondrial density, making them less efficient at removing calcium ions. This fatigue interferes with muscle contractions, reducing force production and the ability to recruit high-threshold motor units. Calcium ion-related fatigue is one of the root causes of reduced hypertrophy.
Testing and Measuring Central Nervous System Fatigue
Central nervous system fatigue can be measured through voluntary activation tests, which assess the recruitment of motor units. These tests evaluate the capacity to produce force and detect the presence of fatigue. Other measurements, such as motor-evoked potentials and intercortical inhibition, provide further insights into CNS fatigue but do not serve as the gold standard. Understanding and managing central nervous system fatigue is essential in designing effective training programs.
Super Spinal and Spinal Level CNS Fatigue
Super spinal CNS fatigue occurs in the sensory part of the brain, limiting the level of central motor command and motor unit recruitment. Factors like discomfort during exercise contribute to perceived effort, reducing the CNS's capacity to produce maximum motor recruitment. Spinal level CNS fatigue refers to desensitization of motor neurons due to repeated signals sent through the spinal cord. Both mechanisms impact motor unit recruitment and overall exercise performance.
Central nervous system fatigue and its duration after a workout
After a workout, central nervous system fatigue occurs, but it dissipates within a few minutes after the workout. However, it has been shown to last for at least a week after certain types of workouts. The fatigue is caused by the desensitization of motor neurons in the spinal cord. This knowledge challenges the popular belief that achieving a high level of centrometic motor unit recruitment during a workout leads to post-workout central nervous activity.
The impact of fatigue on muscle tension and recruitment
Fatigue affects muscle tension and recruitment. The accumulation of metabolites during a workout can create a burning sensation in the muscle, which impacts the ability to produce a motor command and creates super spinal central nervous system fatigue. Short rest periods can lead to metabolite accumulation and central fatigue. Additionally, cardiorespiratory demands can also contribute to central fatigue. To maximize motor unit recruitment and minimize fatigue, longer rest periods and appropriate exercise selection are recommended.
Fatigue mechanisms and their impact on recovery
Fatigue mechanisms, such as calcium ion-related fatigue and muscle damage, affect post-workout recovery. The accumulation of calcium ions during a workout suppresses mechanical tension and inhibits the formation of crossbridges in muscle fibers, leading to reduced force production. Muscle damage caused by enzymes during exercise further impairs the ability to produce force and triggers inflammation. This inflammatory response can cause super spinal central nervous system fatigue. The recovery of these fatigue mechanisms can take several days, depending on the intensity and duration of the workout.
Addressing common misconceptions about fatigue
There are common misconceptions about fatigue, such as the idea that high reps cause more fatigue or that there is weak evidence for the impact of fatigue on muscle tension. Numerous studies have shown that higher reps result in more central fatigue, and there is ample research supporting the relationship between fatigue and muscle tension. It is important to acknowledge the extensive body of literature on fatigue and consider its implications for training strategies and recovery.
In this podcast, we talk about fatigue, starting with the definition and moving on to explain how it works both during and after a strength training workout. https://www.patreon.com/posts/podcast-8-85671319
You can find Chris on his social and publications here -
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You can find Paul on Instagram -
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And his hypertrophy training groups here -
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Valkyrie - https://marketplace.trainheroic.com/workout-plan/team/the-valkyrie
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Garage Gals - https://marketplace.trainheroic.com/workout-plan/team/garage-gals
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