The effects of plyometric jump training on physical fitness attributes in basketball players: A meta-analysis

Background: There is a growing body of experimental evidence examining the effects of plyometric jump training (PJT) on physical fitness attributes in basketball players; however, this evidence has not yet been comprehensively and systematically aggregated. Objective: To meta-analyse the effects of PJT on measures of physical fitness in basketball players compared with a control condition. Data sources: A systematic literature search was conducted in the databases PubMed, Web of Science, and SCOPUS up to July 2020. Study eligibility criteria: Peer-reviewed controlled trials with baseline and follow-up measures investigating the effects of PJT on physical fitness attributes (muscle power [i.e. jumping performance], linear and change-of-direction sprint speed, balance, muscle strength) in basketball players, with no restrictions on their playing level, sex, or age were included. Study appraisal and synthesis methods: Hedge`s g effect sizes (ES) were calculated for physical fitness variables. Using a random-effects model, potential sources of heterogeneity were selected, including subgroup analyses (age, sex, body mass, height) and single training factor analysis (programme duration, training frequency, total number of training sessions). Computation of meta-regression was also performed. Results: Thirty-two studies were included involving 818 total basketball players. Significant (p<0.05) small-to-large effects of PJT were evident on vertical jump power (ES=0.45), countermovement jump height with (ES=1.24) and without arm swing (ES=0.88), squat jump height (ES=0.80), drop jump height (ES=0.53), horizontal jump distance (ES=0.65), linear sprint time across distances <10 m (ES=1.67) and >10 m (ES=0.92), change-of-direction performance time across distances <40 m (ES=1.15) and >40 m (ES=1.02), dynamic (ES=1.16) and static balance (ES=1.48), and maximal strength (ES=0.57). The meta-regression revealed that training duration, training frequency, and total number of sessions did not predict the effects of PJT on measures of physical fitness. Subgroup analysis indicated larger improvements in older compared with younger players in horizontal jump distance (>17.15 years, ES=2.11; ≤17.15 years, ES=0.10; p<0.001), linear sprint time >10 m (>16.3 years, ES=1.83; ≤16.3 years, ES=0.36; p=0.010), and change-of-direction performance time ≤40 m (>16.3 years, ES=1.65; ≤16.3 years, ES=0.75; p=0.005). Furthermore, greater increases in horizontal jump distance were apparent with >2 compared with ≤2 weekly sessions (p<0.001; ES=2.12 and 0.39, respectively). Conclusions: Data from 32 studies (28 demonstrating moderate-to-high methodological quality) indicates that PJT improves muscle power, linear and change-of-direction sprint speed, balance and muscle strength in basketball players independent of sex, age, or PJT programme variables. However, horizontal jump distance, linear sprint time >10 m and change-of-direction performance time ≤40 m seem to be more responsive to the beneficial effects of PJT among older players.