Strength gains and absence of hypertrophy and cross-education in knee extensors following short-term low-volume eccentric training in untrained young men.

This study investigated the effects of a short-term, low-volume eccentric training protocol on knee extensor strength and thickness in untrained young men, including the potential cross-education effect. Twenty-six healthy male participants with no resistance training experience were assigned to the training (n = 14) or control (n = 12) group. The training group performed five maximal voluntary eccentric contractions of the knee extensors on the dominant leg, twice weekly for 2 weeks. Maximal voluntary contraction torque in isometric (MVIC), concentric (MVCC), and eccentric (MVEC) modes, along with quadriceps muscle thickness, were measured before and after the intervention. Significant increases in the MVIC (15.7% ± 24.8%, d = 0.66), MVCC (8.8% ± 7.3%, d = 0.65), and MVEC (22.1% ± 16.4%, d = 0.87) torques were observed in the trained legs (all p < 0.05). MVIC, MVCC, and MVEC torque showed no significant changes in the untrained legs and the control group. The muscle thickness remained unchanged across all groups. In conclusion, a 2-week protocol involving five maximal eccentric contractions twice weekly effectively increased knee-extensor strength in untrained individuals, while no hypertrophic changes were detected. However, the minimal protocol did not elicit cross-education, suggesting that a higher training volume or longer duration may be necessary to induce this effect. Such a time-efficient strategy may be suitable for early-stage rehabilitation or for populations with limited training capacity.