New study provides hope for injured athletes and aging population.
New research has found that lifting weights with one arm only can actually improve strength in the other arm.
The international study run by Edith Cowan University in Perth, WA also found that exercising one arm only can decrease muscle loss in the other, non-exercised arm.
This research has implications for the aging population, as well as athletes and trainees who have an injury on one side of their body.
In particular, the study looked at the eccentric movement — the lowering portion of the lift. The study found this yielded the most benefit on the inactive arm, even more than a full concentric-eccentric repetition.
Previous research has shown that the eccentric portion of a lift — where the muscle actually lengthens — is more effective at growing muscle than the concentric — muscle shortening — exercises.
“I think this could change the way we approach rehabilitation for people who have temporarily lost the use of one arm or one leg,” said Professor Ken Nosaka from ECU, one of the study’s authors.
“By starting rehab and exercise in the uninjured limb right away, we can prevent muscle damage induced by exercise in the other limb and also build strength without moving it at all.”
Researchers took 30 participants who had one arm immobilised for a period of eight hours a day for the duration of the study. All of these participants were in the age range of 18-34.
These participants were then split into three groups: no exercise; concentric and eccentric exercise; and eccentric exercise only.
The participants performed heavy dumbbell curls three times a week. Each session consisted of between three and six sets of 10 repetitions.
The exercise was performed with the participants’ active arm only. In addition, the exercised arm was always the participants’ preferred arm.
After four weeks, the results showed that the group who performed eccentric exercise only showed an increase in strength. In addition, there was also as a decrease in muscle atrophy in their immobilised arm.
“Participants who did eccentric exercise had the biggest increase in strength in both arms, so it has a very powerful cross-transfer effect,” Professor Nosaka said.
“This group also had just two per cent muscle wastage in their immobilised arm, compared with those who did no exercise who had a 28 per cent loss of muscle. This means that for those people who do no exercise, they have to regain all that muscle and strength again.”
As the study says in its conclusion, “The eccentric-only resistance training of the contralateral arm was more effective to counteract the negative immobilization effects than the concentric-eccentric training.”
Life Fitness offers a range of unilateral equipment, including the Insignia Series and the Hammer Strength Plate Loaded range, which allow exercisers to work one side of the body at a time. In addition, we also supply free weights and accessories.
Valdes, et al. (2020.) ‘Contralateral effects of eccentric resistance training on immobilized arm.’ Scandinavian Journal of Medicine and Sports Science.
First published: 08 September 2020. https://doi.org/10.1111/sms.13821