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Comparison Of Muscular Strength Gains Utilizing Eccentric, Standard And Concentric Resistance Training Protocols

Carothers, Kyle; Carothers, Kyle F; Alvar, Brent A; Dodd, Daniel J; Johanson, Jeremy C; Kincade, Brian J; Kelly, Stephen B

The Journal of Strength & Conditioning Research: January 2010 - Volume 24 - Issue - p 1
doi: 10.1097/01.JSC.0000367079.76059.a5

The purpose of this study was to examine the strength benefits of an eccentric-only protocol versus a standard and concentric-only protocol in a multi-joint lift (bench press). Additionally, a secondary purpose was to examine the same protocol's ability to elicit power benefits (seated medicine ball put). Forty-Two men (mean±SD, age 24.9 ± 5.1 yr., height 71.0 ± 3.0 in, weight 189.2 ±31.1 lbs) with recreational resistance training experience (>6 months at least two times per week) performed two sessions a week for 6 weeks utilizing the bench press exercise. Subjects were tested for concentric, standard and eccentric 1-RM pre and post study. Subjects were randomized into one of three groups, eccentric-only (ECC), standard (ECCON) or concentric-only (CON). Subjects performed 4 sets of 4-8 repetitions with 80% of their 1-RM in the repetition type characterized by their group. Subjects moved up 5% when 4 sets of 8 repetitions were completed successfully. Rest time between sets was fixed at 3-5 minutes. Subjects were also tested for power using a 3-kg seated medicine ball put for distance pre and post study and for body composition using air density plethysmography (Life Measurement Inc., Bod Pod, Concord, CA). All statistics were analyzed using SPSS for Windows 15.0 (Chicago, Ill.). Paired sample t-tests were used to test differences pre to post study. One-Way analysis of variance (ANOVA) was used to analyze percentage differences between groups. Tukey HSD test was used as a post hoc when necessary. The level of significance for statistical analysis was set at p ≤ .05. All three groups significantly increased their strength from pre to post study (p <.01). No significant between group differences were seen in standard or concentric 1-RM. Group ECC showed a significantly greater increase in strength over group (ECCON) in eccentric 1-RM (22% vs. 9%). No significant increases were seen pre to post study or between groups for power. The significant finding of this study was a between group difference between group (ECC) and (ECCON) in the eccentric 1-RM. This finding suggests that eccentric-only protocols preferentially increase strength development over standard protocols. Standard protocols are commonly utilized in athletic resistance training protocols. This finding becomes even more significant when considering the magnitude of the gain (22% in only 6 weeks) with a recreationally-trained group of participants. Increases of this magnitude are usually attributed to neural changes in untrained subjects. These results suggest that eccentric muscle actions are underutilized in standard resistance training protocols. This evidence could indicate that athletes possessing low levels of eccentric strength may have a diminished capability to perform the stretch-shortening cycle (SSC); the SSC is a sequence of movements utilizing an eccentric muscle action immediately followed by a concentric muscle action in order to produce a more forceful concentric muscle action. The SSC is commonly used in athletic activities like running, jumping and throwing. Future research should examine the ability of eccentric-only resistance training protocols to elicit performance benefits in athletic populations especially as it relates to increasing the capability of the SSC.

© 2010 National Strength and Conditioning Association