Progress Killers: Hard Cardio and CNS Fatigue – Bigger Stronger Leaner – COMMUNITY

Facts About CNS Fatigue

main point

• very much like overtraining Doesn’t mean training too much, central fatigue has nothing to do with feeling tired. It’s just a weakened central drive from the motor cortex to the musculature.
• To function, high-threshold motor units (fast twitch fibers) requires a strong excitatory signal. Central fatigue weakens this signal, making it harder for these fibers to recover, even during sets to failure. This is true for strength, speed, power and even hypertrophy, since fast-twitch fibers have greater growth potential.
• We used to think lifting weights was the hardest thing for the nervous system. This is not untrue. When you do heavy compound lifts, you need more central nervous system activity (motor skill complexity, higher tension, etc.)
• Failure also increases central fatigue. That last rep felt like a best effort rep.
• But the main factor that increases central fatigue is vigorous aerobic exercise. We’re not talking long runs, but the kind of high-intensity energy system that makes you feel like you’re drowning while being on fire at the same time: high-intensity interval training, the energy burn of a CrossFit workout, etc.
• The main triggers of central fatigue are signals of pain and discomfort. The more signals sent to the brain, the more the brain shuts down to prevent damage. Central fatigue is a protective mechanism.
• HIIT sends out these signals. From a neurological standpoint, high-intensity HIIT training may be more damaging than weight training.
• Inhibitory signals leading to central fatigue can last up to 48 hours. Doing high-intensity aerobic exercise the day before lifting weights may affect the effectiveness of weight training.
• I only use HIIT classes once a week at the end of my fat loss phase. (Longer calorie-burning sessions, such as walking with a heavy backpack, are less damaging to the nervous system.) I’m not saying don’t use high-intensity interval training, but don’t do it every day and keep the central fatigue mental.

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