Effects of Off-Season Heavy-Load Resistance Training on Lower Limb Mechanical Muscle Function and Physical Performance in Elite Female Team Handball Players

Background/Objectives: Team handball involves a high number of rapid and forceful muscle actions. Progressive heavy-load resistance training is known to enhance mechanical muscle function; however, its transfer into functional performance in team handball athletes remains largely unknown. The current study aimed to analyze the effects of eight weeks undulating heavy-load resistance training on lower limb mechanical muscle function and sports-specific performance in elite female team handball players. Methods: Players from the Danish Women’s Handball League were block randomized to perform an off-season resistance training program (RT, n = 12, 23.0 ± 2.7 yr) or follow a training-as-usual control program (CON, n = 15, 24.1 ± 3.8 yr). All study participants were tested before and after an eight-week period during the off-season phase, including assessments of maximal isometric knee extensor and flexor peak torque, rate of torque development, countermovement jump (CMJ) power/work, and sports-specific performance (maximal vertical countermovement jump height, sprint capacity, team handball-specific on-court agility). Results: Agility performance improved for RT (−3.5%, p = 0.008), different from CON (p < 0.001) following eight weeks of designated resistance training. Additionally, CON demonstrated impaired agility (+4.0–7.3%, p < 0.05) and 20-m sprint (+1.9%, p = 0.002) performance. Maximal knee extensor peak torque increased in RT (4.5%, p = 0.044). Vertical CMJ flight height (JH) increased in both groups (RT +4.8%, p = 0.012, CON +8.4% p = 0.044); however, jump height relative to ground level (JHGL) increased in RT only (+8.0%, p = 0.013). Conclusions: In conclusion, designated resistance training during the off-season period is effective in maintaining and improving essential components of sports-specific performance and maximal knee extensor strength in elite female team handball players. Comparable protocols of twice-a-week heavy-load resistance training may also be beneficial in other types of intermittent elite team sports (i.e., football, basketball) that include maximal jumping actions, short-distance sprints, and rapid change of direction movements.