Exercising one arm gives twice the benefits

How cool is this?  A new research study from Edith Cowan University shows training one arm improves strength and decreases muscle loss in the other – without even moving it.  

30 healthy participants had their non-dominant arm immobilised for a minimum of 8 hours a day for 4 weeks. The group were randomly allocated into 3 groups (no exercise, a combination of eccentric and concentric exercise or eccentric exercise only).  

Eccentric exercise is when the contracting muscle is lengthening (e.g. when lowering a dumbbell in bicep curls, sitting on a chair slowly or walking downstairs).  Concentric exercise is when the muscle contracts while producing force (e.g. lifting a dumbbell).  Previous research shows that eccentric exercise is more effective at growing muscle than concentric exercise.  

The group who used a heavy dumbbell to perform only eccentric exercise on their active arm showed increased strength and decreased muscle wasting in their immobilised arm.  Participants who did only eccentric exercises had the biggest increase in strength in both arms.  This group also had just 2% muscle wastage in their immobilised arm, compared with those who did no exercise who showed a 28% loss of muscle. While only a small study, these findings may have important implications for post-injury and stroke patients.  By starting rehab and exercise in the uninjured limb straight away we can build strength in the injured limb without even moving it.

Journal Reference: Valdes, O., Ramirez, C., Perez, F., Garcia‐Vicencio, S., Nosaka, K., & Penailillo, L. (2020). Contralateral effects of eccentric resistance training on immobilized arm. Scandinavian Journal Of Medicine & Science In Sports. doi: 10.1111/sms.13821

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