Effectiveness of Accentuated Eccentric Loading: Contingent on Concentric Load

Abstract

Purpose: To identify acute effects of a single accentuated eccentric loading (AEL) repetition on subsequent back-squat kinetics and kinematics with different concentric loads. Methods: Resistance-trained men (N = 21) participated in a counterbalanced crossover design and completed 4 protocols (sets × repetitions at eccentric/concentric) as follows: AEL65, 3 × 5 at 120%/65% 1-repetition maximum (1-RM); AEL80, 3 × 3 at 120%/80% 1-RM; TRA65, 3 × 5 at 65%/65% 1-RM; and TRA80, 3 × 3 at 80%/80% 1-RM. During AEL, weight releasers disengaged from the barbell after the eccentric phase of the first repetition and remained off for the remaining repetitions. All repetitions were performed on a force plate with linear position transducers attached to the barbell, from which eccentric and concentric peak and mean velocity, force, and power were derived. Results: Eccentric peak velocity (−0.076 [0.124] m·s−1; P = .01), concentric peak force (187.8 [284.4] N; P = .01), eccentric mean power (−145.2 [62.0] W; P = .03), and eccentric peak power (−328.6 [93.7] W; P < .01) during AEL65 were significantly greater than TRA65. When collapsed across repetitions, AEL65 resulted in slower eccentric velocity and power during repetition 1 but faster eccentric and concentric velocity and power in subsequent repetitions (P ≤ .04). When comparing AEL80 with TRA80, concentric peak force (133.8 [56.9] N; P = .03), eccentric mean power (−83.57 [38.0] W; P = .04), and eccentric peak power (−242.84 [67.3] W; P < .01) were enhanced. Conclusions: Including a single supramaximal eccentric phase of 120% 1-RM increased subsequent velocity and power with concentric loads of 65% 1-RM, but not 80% 1-RM. Therefore, AEL is sensitive to the magnitude of concentric loads, which requires a large relative difference to the eccentric load, and weight releasers may not need to be reloaded to induce performance enhancement.

Accentuated Eccentric Loading in the Bench Press: Considerations for Eccentric and Concentric Loading

“…Prior research implementing AEL using 120% 1-RM in the bench press and the back squat also found differences in the effectiveness of AEL depending on the concentric load [2,3]. These same studies also found a decrease in concentric velocity during the AEL repetition with 120% 1-RM; thus, the heavier eccentric loading may reduce the explosive abilities in the subsequent concentric phase [2,3]. However, when attempting to increase maximal force production, heavier eccentric loading during AEL (120% compared to 105%) would logically be more suited in driving that response, but little evidence supports an optimal eccentric overload [4].…”

“…First, we did not measure the segment length of the arms for the subjects, which may have provided greater evidence on the effects of barbell displacement on AEL's effectiveness. Secondly, heavier loads during AEL may reduce volitional eccentric velocities [2,3,13] and resultantly blunt potential immediate concentric performance enhancement. However, due to unreliable eccentric velocity data from the linear position transducer, these data were not presented in the current study.…”

“…In prior bench press literature, AEL using 120% 1-RM decreased that repetition’s concentric velocity during concentric loads of 50% and 65% 1-RM [ 2 ]. Prior research implementing AEL using 120% 1-RM in the bench press and the back squat also found differences in the effectiveness of AEL depending on the concentric load [ 2 , 3 ]. These same studies also found a decrease in concentric velocity during the AEL repetition with 120% 1-RM; thus, the heavier eccentric loading may reduce the explosive abilities in the subsequent concentric phase [ 2 , 3 ].…”

“…One method of acutely enhancing concentric velocity is accentuated eccentric loading (AEL), which is implemented by overloading the eccentric action during exercises involving the complete stretch shortening cycle (i.e., eccentric to concentric action) [1]. During the bench press exercise, AEL has demonstrated efficacy in potentiating acute performances compared to traditional loading (TRAD) where the eccentric load is the same as the concentric load [2][3][4][5][6]. However, divergent outcomes have been demonstrated, which may be partly attributed to differences in phasic loading and other variations between AEL protocols [2,4,6,7].…”

“…In one example, AEL did elicit a favorable effect on power output in the bench press with a fixed concentric load (50% 1-RM), while the corresponding optimal eccentric overload was unique to the individual [ 4 ]. Further, the concentric loads used when implementing AEL have been shown to dictate the efficacy of AEL for increasing concentric velocity [ 3 ]. Others found no change in concentric velocity when using AEL with 105% and concentric loads of 80% 1-RM [ 6 ].…”