Gaining Physical Strength Requires Training the Mind too, Study Suggests
How do we gain physical strength? Isn’t it by exercising our body, particularly our muscles? That’s right. But strength depends on more than the muscle. According to a new study, it involves exercising the nervous system too.
Over the past years, researchers revealed that lifting more repetitions of lighter weight can build muscle mass just as well as fewer reps of heavier weight. But if strength differs even when muscle mass does not, what explains the disparity?
In the new study, researchers from University of Nebraska-Lincoln sought to figure out the answer. They randomly assigned 26 men to train for six weeks on a leg-extension machine loaded with either 80 or 30 percent of the maximum weight they could lift. Three times per week, the participants lifted until they could not complete another repetition.
At the same time, researchers supplied an electric current to the nerve that stimulates the quadriceps muscles used in leg extensions. Even at full effort, most people do not generate 100 percent of the force their muscles can physiologically produce, Jenkins said. By comparing the force of a participant’s "hardest" unassisted kick with the maximum force they can generate when aided by electric current, scientists can determine how much of that capacity a person has reached - a measure known as voluntary activation.
They found that the voluntary activation of the low-load group increased from 90.07 to 90.22 percent - 0.15 percent - over a three-week span. The high-load group saw their voluntary activation jump from 90.94 to 93.29 percent, a rise of 2.35 per cent.
"During a maximal contraction, it would be advantageous if we are activating - or more fully activating - more motor units," lead author Nathaniel Jenkins said. "The result of that should be greater voluntary force production - an increase in strength. That’s consistent with what we’re seeing."
Their findings suggest that the nervous system activates more of those motor neurons - or excites them more frequently - when subjected to high-load training. That increased excitation could account for the greater strength gains despite comparable growth in muscle mass.
The new study was published in the journal Frontiers in Physiology.
Source of this article:
Greater Neural Adaptations following High- vs. Low-Load Resistance Training
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