Can In-Season Nordic Hamstring Exercise Microdosing Maintain Eccentric Hamstring Strength?

Exercise microdosing has been adopted in sports to maintain physical capacities throughout the competitive season. This study aimed to determine whether in-season Nordic hamstring exercise microdosing could retain eccentric hamstring strength after a preseason Nordic hamstring exercise program. Thirty-four athletes completed a 5-week preseason program including a typical-volume Nordic hamstring exercise protocol (up to 60 repetitions/wk). Athletes were then randomized to either a control group, which performed no Nordic hamstring exercise during the in-season period, or a microdose group, which performed one set of six Nordic hamstring exercise repetitions per week. Eccentric hamstring strength was assessed at baseline, immediately after the preseason program, and after 5 and 10 weeks of the in-season period. From baseline to the end of the preseason program, athletes experienced a mean increase of 9.5% (95% confidence interval: 5.3 to 14.3%) in eccentric hamstring strength (microdose: 317±82 N to 346±82 N and control: 292±82 N to 321±82 N). After 5 weeks of the in-season period, strength values returned to baseline levels (microdose: 324±83 N and control: 289±83 N) and remained stable through the 10^th in-season week (microdose: 330±83 N and control: 290±84 N). No significant between-group differences were observed. In conclusion, this microdose strategy was insufficient to retain eccentric hamstring strength after the preseason training period.