Effect of Eccentric Training with Different Durations, Intensities, and Contraction Velocities on Upper Limb Muscle...

Eccentric training may be more effective for muscle strength, but the optimal duration, intensity, and contraction velocity for improving upper limb strength remain unclear. We conducted a search across four databases (PubMed, Embase, Web of Science, and Cochrane) to evaluate the impact of eccentric training on upper limb skeletal muscle strength. A meta-analysis using standardized mean differences (SMDs) and 95% confidence intervals (CIs) was performed. The results from 11 studies involving 368 participants indicated that eccentric training significantly enhanced upper limb strength (SMD = 0.55, CI: 0.32-0.79). Subgroup analysis showed a slight increase in strength in the 1-4 week period (SMD = 0.38, CI: 0.02-0.73), a significant increase in the 4-8 week period (SMD = 0.69, CI: 0.27-1.10), and a substantial increase at 20 weeks (SMD = 0.71, CI: 0.22-1.21). Moderate intensity showed moderate improvements (SMD = 0.47, CI: 0.18-0.77), while high intensity led to significant adaptations (SMD = 0.70, CI: 0.30-1.10). Rapid eccentric contractions (SMD = 0.70, CI: 0.39-1.02) outperformed slow contractions (SMD = 0.35, CI: -0.01-0.71). Eccentric training is effective, with significant results generally requiring 4-8 weeks of high-intensity rapid eccentric training.