New research shows that the advantage of exercising one arm is double the benefit of


New research from Edith Cowan University (ECU) has shown that exercising one arm can, without even moving it, increase strength and decrease muscle loss in the other arm.

By conducting eccentric exercises on the opposite arm, the results could help combat the muscle atrophy and strength loss that often occurs in an immobilized arm, such as after an injury.

The contracting muscle stretches during eccentric movements, such as during biceps curls while lowering a dumbbell, sitting slowly in a chair or ascending stairs. Previous research has shown that these muscle building exercises are more effective than concentric muscle shortening exercises, such as raising a dumbbell or ascending stairs.

A Modern Thought Way
Professor Ken Nosaka of the School of Medical and Health Sciences of ECU was part of the international study and said the results could challenge traditional methods of recovery and improve results for patients after injuries and strokes.

“I think this could change the way we approach rehabilitation for people who have temporarily lost the use of an arm or a leg,” Professor Nosaka said.

“By starting rehab and training immediately in the uninjured limb, we can prevent muscle damage induced by training in the other limb and also build strength without moving it at all.”

The opposite influence
The study involved 30 participants who spent four weeks immobilizing one arm for at least eight hours a day.

The group was then split into three classes, some of which did no exercise, some of which did a combination of eccentric and concentric exercise, and the rest of which did eccentric exercise only.

The community performing only eccentric exercises for the active arm with a heavy dumbbell showed an increase in strength and a decrease in muscle atrophy or atrophy in their immobilized arm, Professor Nosaka said.

“The participants who performed eccentric exercises had the greatest increase in strength in both arms, so there is a very strong cross-transfer effect,” he said.

Compared to those who did no exercise, who had 28 percent muscle atrophy, this category also had just two percent muscle atrophy in their immobilized arm.

“That means the people who don’t do exercise have to rebuild all that muscle and strength.”

The future for rehab
Professor Nosaka said he is preparing to further extend the analysis to other muscles and gestures of the arm.

“In this study, we focused on the elbow flexors because this muscle is often used as a model to study the effects of immobilization on strength and size, and of course it is an important muscle for arm movement,” he said.

“In the future, we hope to study how eccentric training can help improve motor function, movement and fine muscle control, which is especially important for stroke and rehabilitation patients.”

Professor Nosaka also said that for athletes who can start healing earlier after an injury, this form of training is useful.

‘Contralateral Effects of Immobilized Arm Eccentric Resistance Exercise’ by Omar Valdes, Carlos Ramirez, Felipe Perez, Sebastian Garcia-Vicencio, Kazunori Nosaka and Luis Penailillo, Scandinavian Journal of Medicine and Sports Science, 8 September 2020. DOI: 10.1111/sms.138211/sms.


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