It is common knowledge that lifting weights increases strength — but it has never really been determined just how much and how often people should lift. New data reveals that while light weight lifting builds muscle mass, heavy weight lifting makes muscles stronger. The reason behind this, researchers say, is due to the neural connections the brain and body make while lifting heavy weights.
Motor neurons relay signals from the brain to the muscles. This is how we decide when and how to flex our muscles. Researchers noted that heavy lifting engaged the neural connections between these cells more so than light weight lifting, even if one does fewer reps. (Related: Increase Strength and Metabolism: Lift Heavier Weights for Fewer Repetitions.)
Researchers recruited 26 regular gym-goers (all men) and observed their training sessions for a period of six weeks. Participants were asked to use a leg-extension machine loaded with either 30 or 80 percent of the maximum weight they could lift. The team then noted how many reps each participant could make in a week. It was found that both light and heavy lifting experienced the same amount of muscle growth. However, those who carried heavy weights increased their strength by around ten pounds.
Examined even further, each man was strapped to a machine that supplied an electric current to the nerves that stimulated the leg muscles. This electrical stimulation device was used for a basis of comparison to determine how each participant’s nerve cells could achieve 100 percent efficiency, which cannot be achieved through exercise alone. Researchers repeated this test several times over three weeks. During this trial period, the team saw that those who lifted light weights increased their nerve capacity from 90.7 percent to 90.22 percent, which is hardly a difference. Those who lifted heavy weights, on the other hand, increased their nerve capacity by 2.35 percent, with a jump from 90.94 percent to 93.29 percent.
Professor Nathaniel Jenkins, who conducted the research, hypothesized that the increase in nerve capacity directly translated into muscle strength. He claims that high-load training is “more efficient” and prompts “greater [neural cell] adaptations.”
Bigger is not always better
The assumption that bigger bodies are stronger is misleading. There is evidence that proves that those with a bigger frame are more capable of carrying heavier loads; but this is not entirely inclusive nor conclusive of strength. Body-building experts, along with medical professionals, are now noting a distinct nuance between body mass and strength. Most indicative of strength, these professionals say, is how well-engaged motor neurons are.
The power of a muscle’s contraction is heavily reliant on neural associations. The more motor neurons are activated, as well as the strength of impulse sent by each cell, determine the quantity of muscle fibers that contract. Heavy weight lifting is more effective in making motor neurons act more efficiently. In a sedentary person, motor neurons still discharge impulses, but in a disorderly fashion. Constant training improves this process, generating more powerful nerve impulses. To fully reach this state, people should perform weight training exercises with loads that are 80 percent of their maximum strength.
Understand the hidden implication of this: there will be days when one feels stronger. This has nothing to do with the size of the muscles, but the efficiency of the central nervous system. People who are not well-rested will feel minute differences in their overall strength.