Chronic Adaptations to Eccentric Cycling Training: A Systematic Review and Meta-Analysis

Abstract

This study aimed to investigate the effects of eccentric cycling (ECC_CYC) training on performance, physiological, and morphological parameters in comparison to concentric cycling (CON_CYC) training. Searches were conducted using PubMed, Embase, and ScienceDirect. Studies comparing the effect of ECC_CYC and CON_CYC training regimens on performance, physiological, and/or morphological parameters were included. Bayesian multilevel meta-analysis models were used to estimate the population's mean difference between chronic responses from ECC_CYC and CON_CYC training protocols. Group levels and meta-regression were used to evaluate the specific effects of subjects and study characteristics. Fourteen studies were included in this review. The meta-analyses showed that ECC_CYC training was more effective in increasing knee extensor strength, vastus lateralis fiber cross-sectional area, and six-minute walking distance compared to CON_CYC. Moreover, ECC_CYC was as effective as CON_CYC in decreasing body fat percentage. CON_CYC was more effective in increasing V˙O2max and peak power output attained during concentric incremental tests. However, group-level analyses revealed that ECC_CYC was more effective than CON_CYC in improving V˙O2max in patients with cardiopulmonary diseases. ECC_CYC is a viable modality for exercise interventions aiming to improve parameters of muscle strength, hypertrophy, functional capacity, aerobic power, and body composition, with more advantages than CON_CYC training in improving neuromuscular variables.

Keywords: COPD; aerobic capacity; eccentric exercise; strength.

Figure 1

Flow diagram of the selection process of eligible studies. Abbreviations: CON_CYC—concentric cycling; ECC_CYC—eccentric cycling.

Figure 2

Forest plot of effect sizes (% mean difference) of CON_CYC training (A), ECC_CYC training (B), and net effect between training modalities (C) on isometric peak torque. Heterogeneity between effects of CON_CYC training (D), ECC_CYC training (E), and net effects (F). The densities represent model estimates (i.e., the posterior distribution). Black dots and whiskers are the posterior effect size median and 95% credible interval, respectively. The triangles are the studies’ observed mean effect sizes, and their sizes represent the precision of the effect, presented as the inverse of the standard error (1/SE), i.e., the larger the size of the triangle, the smaller the standard error. The letters a, b, c, and d in Lewis et al. (2018) [25] indicate assessments performed at different time points (after 3, 5, 7, and 8 weeks, respectively). The letters a, b, c, d, e, f, g, h, and i in LaStayo et al. (2000) [24] indicate assessments performed at different time points (after 1, 2, 3, 4, 5, 6, 7, 8, and 10 weeks, respectively). The letters a, b, c, d, e, f, and g in LaStayo et al. (1999) [46] indicate assessments performed at different time points (after 1, 2, 3, 4, 5, 6, and 7 weeks, respectively). Abbreviations: CON_CYC—concentric cycling; ECC_CYC—eccentric cycling. References: [14,19,20,24,25,26,34,35,44,45,46].

Figure 3

Meta-regression derived changes pre-to-post on CON_CYC and ECC_CYC conditions for isometric peak torque. Posterior medians with 95% credible intervals for conditional effects regarding the duration of the intervention adjusted for the minimum (A), mean (B), and maximum (C) values of $\dot{V}{O}_{2\max }$. observed on subjects of included studies and for $\dot{V}{O}_{2\max }$ adjusted to the minimum (D), mean (E), and maximum (F) values of intervention duration observed in the included studies. Modifying effects (posterior median [95% credible intervals]) in relation to the reference condition * (G). Heterogeneity as standard deviations (tau) values for random effects included in the meta-regression (H). Abbreviations: CON_CYC—concentric cycling; ECC_CYC—eccentric cycling; $\dot{V}{O}_{2\max }$—maximal oxygen uptake. * Reference condition adjusted to CON_CYC, with 7 days of intervention, and subjects $\dot{V}{O}_{2\max }$ of 16 mL/kg/min.

Figure 4

Forest plot of effect sizes (% mean difference) of CON_CYC training (A), ECC_CYC training (B), and net effect between training modalities (C) on peak power output. Heterogeneity between effects of CON_CYC training (D), ECC_CYC training (E), and net effects (F). The densities represent model estimates (i.e., the posterior distribution). Black dots and whiskers are the posterior effect size median and 95% credible interval, respectively. The triangles are the studies’ observed mean effect sizes, and their sizes represent the precision of the effect, presented as the inverse of the standard error (1/SE), i.e., the larger the size of the triangle, the smaller the standard error. Abbreviations: CON_CYC—concentric cycling; ECC_CYC—eccentric cycling. References: [14,19,20,23,25,26,35,43,44,45].

Figure 5

Meta-regression-derived changes pre-to-post on CON_CYC and ECC_CYC conditions for the peak power output of an incremental test. Posterior medians with 95% credible intervals for conditional effects regarding the duration of the intervention adjusted for the minimum (A), mean (B), and maximum (C) values of $\dot{V}{O}_{2\max }$. observed on subjects of the included studies and for $\dot{V}{O}_{2\max }$ adjusted to the minimum (D), mean (E), and maximum (F) values of intervention duration observed in the included studies. Modifying effects (posterior median [95% credible intervals]) in relation to the reference condition * (G). Heterogeneity as standard deviations (tau) values for random effects included in the meta-regression (H). Abbreviations: CON_CYC—concentric cycling; ECC_CYC—eccentric cycling; $\dot{V}{O}_{2\max }$—maximal oxygen uptake. * Reference condition adjusted to CON_CYC, with 35 days of intervention, and subjects $\dot{V}{O}_{2\max }$ of 16 mL/kg/min.

Figure 6

Forest plot of effect sizes (% mean difference) of CON_CYC training (A), ECC_CYC training (B), and net effect between training modalities (C) on maximal oxygen uptake. Heterogeneity between effects of CON_CYC training (D), ECC_CYC training (E), and net effects (F). Group-level effects of intervention duration of CON_CYC training (G), ECC_CYC training (H), and net effect between training modalities (I) on maximal oxygen uptake. Heterogeneity between group-level effects of intervention duration of CON_CYC training (J), ECC_CYC training (K), and net effects (L). Group-level effects of the population of CON_CYC training (M), ECC_CYC training (N), and net effect between training modalities (O) on maximal oxygen uptake. Heterogeneity between group-level effects of the population of CON_CYC training (P), ECC_CYC training (Q), and net effects (R). The densities represent model estimates (i.e., the posterior distribution). Black dots and whiskers are the posterior effect size median and 95% credible interval, respectively. The triangles are the studies’ observed mean effect sizes, and, in panels a, b, and c, their sizes represent the precision of the effect, presented as the inverse of the standard error (1/SE), i.e., the larger the size of the triangle, the smaller the standard error. Abbreviations: CON_CYC—concentric cycling; ECC_CYC—eccentric cycling. References: [19,20,23,24,25,26,43,44,45].

Figure 7

Forest plot of effect sizes (% mean difference) of CON_CYC training (A), ECC_CYC training (B), and net effect between training modalities (C) on six-minute walking distance. Heterogeneity between the effects of CON_CYC training (D), ECC_CYC training (E), and net effects (F). Group-level effects of intervention duration of CON_CYC training (G), ECC_CYC training (H), and net effect between training modalities (I) on six-minute walking distance. Heterogeneity between group-level effects of intervention duration of CON_CYC training (J), ECC_CYC training (K), and net effects (L). The densities represent model estimates (i.e., the posterior distribution). Black dots and whiskers are the posterior effect size median and 95% credible interval, respectively. The triangles are the studies’ observed mean effect sizes, and, in panels a, b, and c, their sizes represent the precision of the effect, presented as the inverse of the standard error (1/SE), i.e., the larger the size of the triangle, the smaller the standard error. Abbreviations: CON_CYC—concentric cycling; ECC_CYC—eccentric cycling. References: [14,18,19,44,45].