For many years, it was assumed that muscle size was the primary factor that determined strength. Yes, bigger muscles do generally produce greater force. However, as exercise science has evolved, it has become clear that “there is increasing evidence that the neural control of the trained muscle is also altered, allowing a greater force production from the muscle” (229). Although there is a correlation between muscle mass and strength, size isn’t the only factor.
Neural Mechanisms Help You Get Stronger
As a result of resistance training, there are multiple changes that occur within the neuromuscular system that lead to strength gains. In fact, increases in strength are inextricably linked to neural adaptations, whereas increased muscle size is not always a factor.
3 Neural factors that contribute to increased strength:
1. Motor unit recruitment is an important neural factor in understanding resistance training. Motor unit recruitment and “synchronization does improve the rate of force development and the capability to exert steady forces” (230). However, the body’s motor units usually aren’t recruited all at the same time. The simultaneous activation of these important motor units can result in sudden, superhuman acts of strength.
2. Another neural factor is autogenic inhibition, an inhibitory mechanism which prevents the muscles from exerting more force than the connecting bones and tissue can withstand. Think of this as a built-in injury prevention system. When these same inhibitory impulses are decreased or counteracted with resistance training, strength gains occur.
3. Lastly, the co-activation of agonist and antagonist muscles also contributes to strength gains as a result of resistance training. In order to maximize strength, the force created by the antagonist muscles must be minimized.
Gains in Muscle Size Means Gains in Strength
If your muscles are getting bigger, you are indeed getting stronger. Muscle fibers adapt to resistance training by changing in size and amount. With disuse (from injury or other inactivity), the muscles shrink or atrophy. Conversely, hypertrophy is the increase in muscle mass as a result of weight-lifting and other strength-training activities.
There are 2 Types of Hypertrophy:
1. Muscle fiber hypertrophy is an increase in the size of existing individual muscle fibers. Resistance training causes a net increase in muscle protein synthesis and thus, muscle fiber hypertrophy, or enlargement.
2. Muscle fiber hyperplasia is an increase in the number of fibers. However, most of the research on hyperplasia has been done on animals. It is still unclear how hyperplasia contributes to muscle mass in humans.
You have now discovered how both neural and muscular adaptations help you get stronger.
Physiology of Sport and Exercise, Kenney, Wilmore,