The level of effort, rather than muscle exercise intensity determines strength gain following a six-week training.

AIM: This study investigated the effect of voluntary motor effort during a low-intensity (30% maximal voluntary contraction [MVC]) muscle exercise training program on increasing muscle strength.

MATERIALS AND METHODS: Eighteen young and healthy individuals were randomly assigned to one of three groups: high mental effort (HME), low mental effort (LME), or a no-training control (CTRL) group. Training lasted for 6weeks (15min/day, 5days/week). The participants' right-elbow flexor muscle strength was measured before and after the training program.

KEY FINDINGS: After training, the HME group gained 20.47±8.33% (P=0.01) strength while the LME and CTRL groups had negligible strength changes (1.89±0.96% and -3.27±2.61%, respectively; P>0.05) despite muscle contraction intensity (30% MVC) sustained during training was the same for the HME and LME groups. These results suggest that the level of effort involved in resistance exercise training plays a critical role in determining the amount of strength augmentation.

SIGNIFICANCE: The finding that high effort combined with low-level physical exercise training can significantly increase muscle strength has rehabilitation applications as many patients and frail older adults have difficulties in participating in high-intensity exercise training such as lifting heavy weights. High effort plus low-level muscle exercise might serve as a safe training regimen for effective muscle strengthening in vulnerable populations.