An eccentric muscle contraction occurs when a muscle creates force as it is lengthened. In the squat exercise, for example, the quadriceps and gluteus muscles are lengthened as the lifter lowers themselves toward the ground. However, the muscles still produce force so the lifter does not drop too quickly or fall to the floor. Another example of an eccentric contraction is the downward phase of the biceps curl exercise, in which the biceps muscle is lengthened but produces force to control the resistance.
In a recent study, researchers examined the potential unique role of eccentric muscle contractions in improving muscle function. Thirty participants completed a 4-week intervention. Ten of the participants performed eccentric-only training with one arm. Another 10 participants performed concentric-eccentric training also with just one arm. For these 20 participants, the arm not used in training was placed in a sling over the 4-week intervention. The purpose of placing the non-training arm in a sling was to immobilise it, similar to how a limb is immobilised during recovery from injury or surgery. The researchers wanted to determine if resistance training with one arm increases muscles strength of the immobilised arm and thus might have implications for physiotherapy.
Participants in the eccentric-only training group performed 3-4 sets of 10 eccentric repetitions of the biceps curl. Participants in the concentric-eccentric training performed 4-6 sets of 10 concentric-eccentric repetitions of the biceps curl. Heavy resistances were used by all participants, and total work performed by the two training groups was equal. Before and after training, isometric and concentric muscle strength of the elbow flexor muscles was measured from the arm that performed the training as well as the non-training immobilised arm. Ten participants in a control group did not perform any training but still had one of their arms immobilised in a sling.
Participants in the control group experienced, on average, a strength loss of 20% in their immobilised arm. Participants who performed concentric-eccentric training did not experience this strength loss. Moreover, participants who performed eccentric-only training increased muscle strength of their immobilised arm by 3-12% – a phenomenon called “cross-education.”
The results from the study illustrate eccentric resistance training of one arm can maintain or improve muscle strength of the opposite arm. This has implications for rehabilitation. Individuals who have their arms in a sling from injury can still perform resistance training with their healthy arm to prevent loss of muscle strength and muscle mass in their immobilised arm.
To apply the findings of this research to the V-Form Trainer:
- attach the handles to the V-Form trainer
- select the “biceps curl” exercise
- select “eccentric only” mode
- select the desired resistance and number of repetitions for the exercise
- set movement range of motion for the exercise with the first 3 calibration reps
- once the exercise begins, pause at the top of the movement to load the eccentric phase
- control the load slowly down to the bottom of the movement
- pause at the bottom to de-load the V-Form
- lift the handles again to the top of the movement range and then repeat until the desired number of repetitions have been completed
Valdes O, et al. Contralateral effects of eccentric resistance training on immobilized arm. Scandinavian Journal of Medicine and Science in Sports 31: 76-90, 2021. DOI: 10.1111/sms.13821.