The effects of 6 weeks of high load or low-load blood flow restriction resistance exercise training on motor unit firing rates in males and females

To stimulate muscle growth, resistance exercises must be performed with adequate duration and precision to activate most of the motor units within the muscle.

In young adults who have not trained before, performing resistance exercises with restricted blood flow for six weeks leads to increases in knee strength, with higher loads producing greater gains. These strength improvements occur without changes in the electrical signals from nerves to muscles, suggesting the muscles themselves become stronger rather than the nervous system driving them harder.

During muscle contractions, women and men show different patterns of nerve signal activity in specific thigh muscles: women have higher nerve firing rates in the outer thigh muscle at low and moderate intensities and in more powerful motor units at higher intensities, while men have higher nerve firing rates in the inner thigh muscle’s initial motor units regardless of intensity.

Men and women show different patterns of nerve signal rates in certain leg muscles during exercise, with women having higher rates in one muscle (vastus lateralis) at lower effort levels and men having higher rates in another muscle (vastus medialis) during initial muscle activation, suggesting that neural control differs by muscle and how hard the muscle is working.

After six weeks of strength training, the nerve signals to the main thigh muscles do not become stronger in young people who have not trained before.

Electrical signals controlling muscle contraction are consistently stronger in the outer thigh muscle (vastus lateralis) than in the inner thigh muscle (vastus medialis), regardless of the intensity of the contraction, the person's sex, or their training background.