Short-Term Effects of Eccentric Overload Versus Traditional Back Squat Training on Strength and Power

Background of Study: Benefits of training with eccentric overload (EO) include increased concentric strength, eccentric strength, explosiveness, and muscle adaptation. There is a lack of practical strength training protocols that compare traditional methods and EO. Purpose: Compare effects of eccentric overload versus traditional training on strength and performance. Method: Thirty-three trained males (age: 21.4 ± 2.7 years) were divided into three groups: Traditional (TRAD, N =12), EO, (N =11), and Control (CTRL, N =10). Back squat training lasted five weeks. The average intensity (%1RM) for each repetition and the volume was the same between groups. Results: Multiple 3x2 (Group x Time) Analyses of Variance (ANOVAs) were performed on the following: 1RM, eccentric 1RM (Ecc1RM), countermovement jump height (CMJ), and 20-meter sprint times. A significant Group x Time interaction (p =.001) was observed for Ecc1RM. The source was a significant increase in Ecc1RM strength from pre to post-test for the EO group (+16.9 kg) and TRAD group (+12.7 kg). A significant Group x Time interaction (p =.026) was observed for CMJ. The source was a significant increase in CMJ height from pre to post-test for the EO group (+3.8 cm) and TRAD group (+2.9 cm). Conclusions: Using EO and TRAD during a short-term back squat training protocol enhanced vertical jump explosiveness and eccentric strength. Athletes aiming to enhance lower body explosiveness and eccentric strength are likely benefit from EO. Athletes looking to enhance concentric strength should adhere to methods whereby paired concentric-eccentric actions are the primary focus.