Cross-Education Strength and Activation After Eccentric Exercise

Abstract

Context: After injury, eccentric exercise of the injured limb is often contraindicated. Cross-education training, whereby the uninvolved limb is exercised, is an alternative that may improve quadriceps muscle strength and activation in the unexercised limb.Objective: To determine the effect of eccentric exercise on quadriceps strength and activation gains in the unexercised limb.Patients or Other Participants: Eighteen healthy individuals were randomly assigned to an eccentric training group or a control group.Intervention(s): Quadriceps strength and activation measures were collected at preintervention, midintervention, and postintervention. Eccentric training participants exercised their dominant limb with a dynamometer in eccentric mode at 608/s, 3 times per week for 8 weeks.Main Outcome Measure(s): Quadriceps strength was quantified at 308 and 608/s in concentric and eccentric modes. Quadriceps activation was assessed using the burst superimposition technique and quantified via the central activation ratio. A 2 3 3 repeated-measures analysis of variance was used to detect the effects of group and testing session on quadriceps strength and activation. Where appropriate, post hoc Bonferroni multiple-comparisons procedures were used. Results:We found greater eccentric strength in the unexercised limbs of eccentric training participants between preintervention and midintervention and between preintervention and postintervention (preintervention to midintervention: 308/s P ¼ .05; preintervention to postintervention: 308/s P ¼ .02, 608/s P ¼ .02). No differences were noted in concentric strength (P . .05). An overall trend toward greater quadriceps activation in the unexercised knee was detected between preintervention and postintervention (P ¼ .063), with the eccentric training group demonstrating a strong effect (Cohen d ¼ 0.83). Control strength did not change (P . .05).Conclusions: Exercising with eccentric actions resulted in mode-specific and velocity-specific gains in quadriceps strength in the unexercised limb. A trend toward greater quadriceps activation in the unexercised knee was noted, suggesting that strength gains may have occurred because of enhanced neural activity. This type of therapy may be a useful addition to rehabilitation programs designed to improve quadriceps strength.

Cross-education effect after unilateral eccentric-only isokinetic vs dynamic constant external resistance training

“…However, changes in concentric peak torque were not significantly different with the control group and they should be interpreted with caution. Indeed, similar to our outcomes, no significant concentric peak torque increase was found after contra-lateral eccentriconly training [25]. A sort of discrepancy was found because of increases in 1RM but not in concentric peak torque.…”

Increased cross-education of muscle strength and reduced corticospinal inhibition following eccentric strength training

“…(Hortoba´gyi et al, 1996;Komi and Buskirk, 1972;575 Pavone and Moffat, 1985). Consequently, the cross-576 transfer of strength following eccentric training was 577 greater following eccentric training which supports the 578 recent finding by Lepley and Palmeri-Smith (2014 (Hortoba´gyi et al, 1997). However, it 590 should be noted, that in the present study, both the con- (Johnson et al, 1976;Dudley et al, 1991).…”

Eccentric Resistance Training in Adults with and without Spinal Cord Injuries

“…Similar to previous literature, continued eccentric strength gains across a training program might be attributed to neural adaptations rather than a hypertrophic response (7,19). Being that those with iSCI progressed similarly in eccentric strength to the able-bodied controls, the improvement may be credited to either intact neural communication from higher brain centers, reflexive responses International Journal of Exercise Science http://www.intjexersci.com 163 at the spinal cord level initiated from the stepping motion, or a combination of both (3).…”