Muscle performance between contra-lateral knee extensors is most often assessed using maximal test for isometric/isokinetic torque evaluation. Recently, the rate of force development scaling factor (RFD-SF) has been used to evaluate neuromuscular capacity with a range of submaximal target peak torques, which could highlight other aspects of inter-limb (a)symmetry. The aim of our study was to investigate the differences, associations, and agreement between inter-limb symmetries of knee extensors using maximal torque (T_max) rate of torque development (RTD), slope of the RFD-SF regression line (k), and theoretical peak of RTD (TP_RTD). A total of 236 young, healthy athletes participated in the cross-sectional study. All participants performed unilateral knee extension (maximal voluntary contraction protocol and RFD-SF protocol) with both legs in the isometric knee dynamometer. Inter-limb symmetries were calculated for each outcome measure. Our results showed significant differences between all symmetry values (T_max (91.7%), RTD (85.2%), k (94.2%), TP_RTD (95.9%)). Significant strong correlations were found between symmetry values calculated from k and TP_RTD (r = 0.88, p < 0.001), while weak correlation was found between T_max and RTD (r = 0.17, p < 0.01. Fair agreement regarding leg dominance was found between T_max and RTD values. Our results suggest that inter-limb (a)symmetries are metric- and task-specific.

Peripheral magnetic stimulation has recently been introduced as a non-invasive but effective physical agent to improve muscle strength and everyday function. The aim of this study was to evaluate the feasibility and safety of an exercise program focusing on the abdominal muscles in combination with the peripheral magnetic stimulation of the abdominal muscles. Male and female overweight and obese adults (n = 19) participated in an eight-week exercise program with the additional peripheral magnetic stimulation of the abdominal muscles. Outcome measures included changes in abdominal subcutaneous fat thickness, trunk muscle strength, body composition, and self-reported body satisfaction. Subcutaneous fat thickness was significantly reduced after the intervention (p < 0.01–p < 0.001). Trunk flexion and left side flexion strength increased significantly after the intervention, although no significant changes were observed for trunk extension (p = 0.07) and right side flexion strength (p = 0.13). The body satisfaction self-assessment score significantly increased (p < 0.01), while body mass, body mass index, and fat mass significantly decreased after the intervention (p < 0.05). Our findings suggest that an exercise program with the additional peripheral magnetic stimulation is feasible and safe for overweight and obese participants. These results support the use of peripheral magnetic stimulation as a safe adjunct to the voluntary abdominal muscle contraction. Future studies are needed to evaluate the efficacy of the additional peripheral magnetic stimulation of the abdominal muscles compared to the voluntary contraction of the abdominal muscles alone.