Lifting lighter weights as effective as heavy weights

By: Dr. Victor Marchione | General Health | Monday, July 10, 2017 - 02:15 PM

Lift WeightsBuilding strength is traditionally achieved through lifting very heavy weights. However, according to a new research study from the University of Nebraska-Lincoln, physical strength may improve just as much from exercising the nervous system as the muscles themselves.

Everyone will tell you that, in order to get stronger and build muscle, you have to lift heavy and perform more repetitions. While this is a tried and true saying, it is tough for many people looking to stay strong throughout the years.

Lifting lighter weight may be the better choice for you

However, previous studies on the topic have found that lifting lighter weights with more repetitions can build muscle just as well as heavy weights with fewer repetitions. However, those who trained with heavier weights did still see better gains in strength compared to people who lifted lighter.

The researchers were not interested in increases in muscle mass. Instead, increases in strength were measured, as that is far more important for overall functionality in day to day life. They sought out to discover the reasons why levels of strength differ, regardless of muscle size.

Their research led them to study the brain and various motor neurons that are responsible for the movement of the bodily limbs.

How muscles work

When muscles contract, they are receiving signals that originate from the neuron-rich motor cortex. These signals travel down the spine, jumping to other motor neurons until they reach their destination, causing a muscle contraction.

The researchers found evidence that the activation of motor neurons—and subsequently more muscle contraction—translated to increased muscle strength, despite the size of the muscle.

The study in question involved 26 men who trained for six weeks on a leg extension workout machine loaded with either 80 or 30 percent of the maximum weight they could lift. For three days out of the week, the participants carried out this exercise until they could not complete any more repetitions.

Both groups saw similar growth in muscle mass, but the group lifting heavier weights saw a roughly 10lb worth increased in strength.

Differences seen

The researchers also applied electrodes for electrical stimulation of the leg nerves that stimulate the quadriceps during exercise. They found that when unassisted by electrical stimulation, none of the participants ever reached 100 percent muscle-use capacity, even when pushing their legs the hardest.

When adding electrical stimulation, the researchers measured the maximum force a participant could generate with stimulation. They called this measurement the “voluntary activation.”

Voluntary activation of the low-load group increased from 90.07 to 90.22 percent over a three-week span. The high-load group saw an increase from 90.94 to 93.29 percent during the same time.

“During a maximal contraction, it would be advantageous if we are activating—or more fully activating—more motor units. The result of that should be greater voluntary force production—an increase in strength. That’s consistent with what we’re seeing,” said Nathaniel Jenkins, an assistant professor of exercise physiology at Oklahoma State University, and conductor of this study.
This study demonstrates how our nervous system plays a vital role in the development of strength. Despite knowing that lifting heavy will lead to increased strength, lifting lighter with more repetition is still a viable option. It’s not only more time efficient, but is easier on the joints of older adults.

Sources:
https://medicalxpress.com/news/2017-07-strength-muscle.html


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