After training one limb to produce force more quickly, the same improvement in the opposite limb fades after four weeks without training, suggesting that the nervous system changes enabling faster...
Mechanism
Synthesis from 1 study
Training one leg makes the brain better at sending fast signals to the other leg, helping it produce force more quickly. But if you stop training, the brain forgets how to send those strong signals, and the improvement goes away — even though the muscle doesn't shrink.
Most probable mechanism
When one side of the body is trained with resistance exercises, the brain becomes better at sending quick, strong signals to the opposite side, making it produce force faster. This improvement fades if training stops, because the brain doesn't keep sending those strong signals without regular practice.
Unilateral resistance training induces neuroplastic changes in the motor cortex that increase the efficiency and magnitude of descending neural signals.
These enhanced descending signals drive more synchronous and rapid recruitment of motor units in the contralateral muscle during the initial phase of contraction.
The increased motor unit recruitment rate during early force development elevates the rate of torque production without changes in muscle size or spinal reflex sensitivity.
Without continued training, the strengthened cortical drive gradually weakens, leading to a return to baseline motor unit recruitment patterns and loss of rapid force production gains.
Evidence from Studies
Supporting (1)
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Contralateral training effects of low-intensity blood-flow restricted and high-intensity unilateral resistance training
Contradicting (0)
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