A concentric muscle contraction occurs when a muscle creates forces as it shortens (e.g., upward lifting phase of the biceps curl exercise). An eccentric muscle contraction occurs when a muscle creates force as it is lengthened (e.g., downward lowering phase of the biceps curl exercise). When performed repeatedly over several weeks, concentric and eccentric muscle contractions do not necessarily lead to the same improvements in health and function.
In a recent study, groups of participants performed low-load eccentric training, 2 times per week for either 8 weeks or 16 weeks. During each exercise session, participants completed 5 sets of 6 eccentric contractions of the biceps curl exercise with a weight of 10% of their individual maximum (~2-3 kilograms). For each repetition of the exercise, the weight was lowered over 3 seconds. Then, to ensure the exercise was eccentric-only, the investigator grabbed the weight from the participant, such that the participant would not lift the weight during the upward concentric phase. After the 6 eccentric repetitions were completed, participants rested for 2 minutes before going on to the next set.
After 8 and 16 weeks of low-intensity eccentric training, participants improved their muscle strength. Interestingly, although training was performed eccentrically, the researchers measured strength isometrically and concentrically. This was done to see if the effects of eccentric training transfers over to other muscle contraction types. The researchers found that 8 weeks of low-intensity eccentric training improved isometric muscle strength by 13% and concentric strength by 16%. Moreover, 16 weeks of low-intensity eccentric training improved isometric strength increased by 30% and concentric strength by 37%. Muscle thickness increased by 4%.
The findings reveal eccentric training performed for several weeks at 10% of maximum improves muscle strength. The result is somewhat surprising – or as the researchers put it, “striking” – given the weight used was minimal. Nevertheless, the effect was demonstrated in two different groups of participants. Thus, for individuals who may be unable to exercise with heavier resistances, minimal resistance that is controlled eccentrically, can still be used to maintain or improve muscle size and strength. Also, study participants improved their isometric and concentric strength, even though they did not perform these types of muscle contractions in their training. Thus, the effects of low-intensity eccentric training are not limited to the specific training movement. They appear to transfer over to other strength tests for the same muscle group. Finally, the strength improvements were cumulative over time. Strength improvements were greater in magnitude after 16 weeks than 8 weeks of training. Thus, over a period of a few months, muscle strength can continue to increase with continued low-intensity eccentric training.
To incorporate the findings of this research on eccentric training into your V-Form trainer:
- attach the handles to the V-Form trainer
- select the “biceps curl” exercise
- select the “eccentric only” mode
- select the desired force and number of repetitions for your set of eccentric curls
- set your full training range
- once the exercise begins, pause at the top of your training range to load the eccentric phase
- control the load slowly down to the bottom of your training range
- pause at the bottom of your training range to de-load the V-Form
- lift the handles again to the top of your training range and then repeat the process until you have completed the desired number of repetitions
Chen TC, et al. Striking muscle adaptations induced by volume-dependent repeated bouts of low-intensity eccentric exercise of the elbow flexors. Applied Physiology, Nutrition, and Metabolism, 2021. DOI: 10.1139/apnm-2020-1016.