Does complex contrast training induce higher physical fitness improvement in stronger compared to weaker individuals?

This study compared the effects of complex contrast training (CCT) on measures of physical fitness in stronger compared to weaker individuals. Forty-one participants were initially recruited for relative strength assessment in the back squat. Thereafter, 26 participants were purposively assigned to either a stronger group (CCT-ST; relative strength ≥1.75; n = 12) or a weaker group (CCT-WK; relative strength <1.55; n = 14). Physical fitness tests were assessed pre- and post-six weeks of CCT training. Tests included 30-m sprint for speed, standing long jump and countermovement jump for power, and isokinetic peak torque of the knee flexors and extensors for strength. ANOVA revealed a significant effect of time for all dependent variables (all p <0.001, ɳp2 = 0.83 – 0.89 [large]). Post-hoc tests indicated significant performance improvements within-group for CCT-ST (all p <0.001, Hedge’s g = 0.27 – 0.98 [small to moderate], %Δ = 3.0 – 16.4) and CCT-WK (all p <0.001, Hedge’s g = 0.37 to 1.34 [small to large], %Δ = 3.1 – 17.4) for all dependent variables. No group-by-time interaction was found for the included variables. In conclusion, CCT intervention provided similar effects on the assessed measures of physical fitness in both stronger as well as weaker active individuals. Therefore, CCT can be an effective training strategy to improve physical fitness among active individuals irrespective of their relative strength.