Effects of Plyometric Training on Lower Body Muscle Architecture, Tendon Structure, Stiffness and Physical Performance: A Systematic Review and Meta-analysis

Abstract

Background Plyometric training (PT) has been widely studied in sport science. However, there is no review that determines the impact of PT on the structural variables and mechanical properties of the lower limbs and physical performance. Objective The aim of this systematic review and meta-analysis was to determine the effects of PT on lower body muscle architecture, tendon structure, stiffness and physical performance. Methods Five electronic databases were analysed. The inclusion criteria were: (1) Availability in English; (2) Experimental studies that included a PT of at least eight sessions; and (3) Healthy adults subjects. Four meta-analyses were performed using Review Manager software: (1) muscle architecture; (2) tendon structure; (3) muscle and tendon stiffness; (4) physical performance. Results From 1008 search records, 32 studies were eligible for meta-analysis. Muscle architecture meta-analysis found a moderate effect of PT on muscle thickness (Standard Mean Difference (SMD): 0.59; [95% Confidence Interval (CI) 0.47, 0.71]) and fascicle length (SMD: 0.51; [95% CI 0.26, 0.76]), and a small effect of PT on pennation angle (SMD: 0.29; [95% CI 0.02, 0.57]). The meta-analysis found a moderate effect of PT on tendon stiffness (SMD: 0.55; [95% CI 0.28, 0.82]). The lower body physical performance meta-analysis found a moderate effect of PT on jumping (SMD: 0.61; [95% CI 0.47, 0.74]) and strength (SMD: 0.57; [95% CI 0.42, 0.73]). Conclusion PT increased the thickness, pennation angle and fascicle length of the evaluated muscles. In addition, plyometrics is an effective tool for increasing tendon stiffness and improving jump and strength performance of the lower body.

Effect of Plyometric Jump Training on Skeletal Muscle Hypertrophy in Healthy Individuals: A Systematic Review With Multilevel Meta-Analysis

“…The main findings of the present meta-analysis indicated small to moderate effects of plyometric jump training on skeletal muscle hypertrophy [SMD = 0.47 (95% CIs = 0.23-0.71)], regardless of sex, age, and training experience. The current outcomes corroborate the results of a recently published systematic review with meta-analysis where authors reported a moderate effect of plyometric jump training on muscle thickness (SMD = 0.59) and fascicle length (SMD = 0.51) in healthy adults (Ramírez-delaCruz et al, 2022). However, our results are relatively more conservative, which we attribute to our more stringent inclusion criteria for plyometric jump training as well as the comparison of the plyometric jump training to an active/ passive control group.…”

“…However, our results are relatively more conservative, which we attribute to our more stringent inclusion criteria for plyometric jump training as well as the comparison of the plyometric jump training to an active/ passive control group. In sum, the findings of the current study as well as those of recent ones (Grgic et al, 2020;Ramírez-delaCruz et al, 2022) question the common belief, indicating that plyometric jump training can indeed increase not only the motor drive to the active muscles but also skeletal muscle hypertrophy.…”

“… Markovic and Mikulic (2010) conducted a comprehensive review of the effects of plyometric jump training on neuromuscular and performance outcomes and concluded that plyometric jump training has the potential to enhance skeletal muscle hypertrophy but to a lesser extent compared with traditional resistance training. Recently, Ramírez-delaCruz et al (2022) conducted a systematic review and meta-analysis on the effects of plyometric jump training on lower body muscle architecture in healthy adults (≥18 years). The authors revealed that plyometric jump training is an effective method to increase muscle thickness of the vastus lateralis, vastus medialis, rectus femoris, and triceps surae.…”

“…For example, some studies have used plyometric jump training with increased or reduced body mass ( Hirayama et al, 2017 ; Ullrich et al, 2018 ; Stien et al, 2020 ), others used a combination of plyometric jump training with traditional resistance training ( Hunter and Marshall, 2002 ; Kijowksi et al, 2015 ) and some of the included studies actually did not use plyometric training at all ( Helland et al, 2017 ; Horwath et al, 2019 ; Kudo et al, 2020 ; van der Zwaard et al, 2021 ). Additionally, the authors calculated within-group pre-post effect size ( Ramírez-delaCruz et al, 2022 ). Of note, such an approach has been criticized as it results in biased outcomes ( Cuijpers et al, 2017 ).…”

“…Given the inconsistent outcomes as to the effects of plyometric jump training on skeletal muscle hypertrophy from individual studies and the methodological shortcomings in a recent meta-analysis ( Ramírez-delaCruz et al, 2022 ), there is a need to systematically summarize the literature and aggregate data from the available studies to draw more conclusive evidence ( Higgins, 2011 ). Additionally, factors such as age, sex, and training experience as well as different training variables like weekly session frequency, number of jumps per session, and training duration appear to moderate the effects of plyometric jump training on measures of physical fitness ( de Villarreal et al, 2009 ; Sáez-Sáez de Villarreal et al, 2010 ; Asadi et al, 2016 ), yet are not well elucidated for skeletal muscle hypertrophy.…”