In a new study published on June 29 in the Journal of Neuroscience, scientists claim that workouts such as weight lifting alters the brain before making any significant changes to the muscles.

In their experiment, the scientists taught macaque monkeys how to strength train. During the process, they analyzed how the exercise transformed their body and brain. The findings of the study revealed that weightlifting strengthens the nervous system through the reticulospinal tract.

The tract is primarily responsible for postural control and locomotion. The researchers found that it was first stimulated before any muscle in the body.

Isabel Glover, an author of the study from Newcastle University, tells Inverse that strength isn't merely about muscle mass. She says that strength builds up because the neural input to the muscles increases upon starting to weight lift. The muscles only begin to get bigger a few weeks later, after the initiation of the activity.

The study subjects were macaque monkeys, whose brain systems were deemed similar to humans, particularly when it comes to movement. According to Stuart Baker, another co-author of the study, the study results should be closely translatable to humans.

The researchers point out that people who lift lift but don't see immediate changes in their bodies should realize that something is occurring in their system. Moreover, intense neural changes in the brain can result in long term physiological benefits.

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The Link Between Brain and Body

In the study, the team stimulated the monkeys' motor cortex and two motor tracts, namely, the corticospinal tract (CST) and reticulospinal tract (RST). They also measured the electrical activity in their arm muscles as they did the weight lifting.

The primary pathway, CST, carries movement-related information from the cerebellum to the spinal cord. This pathway allows animals and humans to move their limbs and trunk, particularly walking or reaching for objects. Meanwhile, the old developmental pathway, RST, which is acknowledged as less dominant, influences muscle tone and posture.

Throughout the training regimen, the team found significant increases in the strength of the old evolutionary pathway (RST), and no change in the main pathway (CST).

After three months of the monkeys' strength training, stimulating the RST gave off a greater response in the spinal cord's side linked to the trained arm. The researchers found that generally, outputs from the RST became more effective during weight training.

Baker explains how their results show that strength training initially increases the intensity of connections from the reticulospinal tract to the spinal cord. After the bond is made, muscles are then activated even more. He adds that this occurs early on, and muscles only grow larger later, giving off maximum strength.

Possible Benefits of Weight Training to Stroke Patients

According to Glover, the results of their study are applicable to bodybuilders and could also aid patients who suffered from a stroke.

 If neural mechanisms of strength can be studied, helping individuals suffering from a loss of strength could also be developed.

Since the indirect pathway is also involved in stroke recovery, this entails that improving the function of a hand-rendered weak by a stroke could be using the same means as strength training in a healthy young bodybuilder, says Baker.

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