The dose–response of the Copenhagen adduction exercise on adductor strength in high-level youth hockey players: A three-arm randomised controlled trial

The aim of this cluster-randomised controlled trial was to investigate the training and detraining effects of two different-volume Copenhagen Adduction Exercise (CAE) protocols on adductor squeeze strength. Thirty high-level rink hockey players (14 y.o.) were allocated to a warm-up low-volume (LVG), high-volume (HVG) protocol, or a control group. Adductor strength change was evaluated over a period of 11 weeks (eight of intervention + three of detraining). Adherence to the intervention and reporting of delayed onset muscle soreness (DOMS) were also collected. Adductor strength increase was significantly higher in HVG compared to LVG (+24%, mean difference 0.68 Nm/kg, p = 0.03) or controls (+34%, mean difference 0.9 Nm/kg, p = 0.009) at the end of the intervention. No significant strength drop was observed after three weeks of detraining in any group (−2.7% − 6%, p = 0.16 - 0.66), while HVG values were still significantly higher compared to controls (+27%, mean difference 0.71 Nm/kg, p = 0.027) at week 11. Compliance was identical in both intervention groups (LVG: 92.3%, HVG: 93.3%) and one case of DOMS was reported across 208 individual sessions (0.48%). The CAE protocol performed twice a week enhances squeeze strength to a further extent compared to one weekly session.