| Summary: | Background: The purpose of this study was to use unilateral neuromuscular training following a period of bilateral training compared to a control detraining group. Functional output measures were used to assess cross-education adaptations with a view to their potential use in the rehabilitation of anterior cruciate ligament (ACL) injuries. No cross-education research to date has incorporated functional interventions or output measures and only one ACL rehabilitation study has investigated the potential effects of cross-education.
Methods: Eighteen recreationally active females (21.2 ± 3 years of age, with a stature of 166.4 ± 6.6 cm, and body mass of 61.9 ± 3.6 kg) were recruited (n = 18). The participants all completed a six week bilateral plyometrics programme to raise their functional performances above their baselines. The participants were then divided into two groups, a cross-education group (CEG) (n = 9) and a detraining group (DTG) (n = 9). The CEG completed a nine week unilateral neuromuscular training programme while the DTG ceased their training. Output measures were recorded before and after the bilateral training programme (weeks 0 and 7) and again post-intervention (week 16) for drop jumps (DJs) and single leg vertical jumps (SLVJs). The data for all tests were recorded using Bioware software and a Kistler 9286A Force Platform (Kistler, UK). Additionally an eight channel surface electromyography (sEMG) unit (ME6000, Megawin sEMG, Finland) and two dimensional video analysis were used for the pre and post-intervention tests at week 7 and 16. The variables tested were peak force (N), force adjusted for bodyweight (N·Kg), contact time (s), average rate of force development
(N·m·s−1), propulsion (m·s−1), deceleration (m·s−1), velocity (m·s−1), power (W), flight time (s), jump height (cm), knee abduction moment probability (KAM) and knee valgus (cm).
Findings: This study found there to be significant effect for DJ velocity on first landing on time (P = 0.02), velocity on take off for SLVJ on interaction (P = 0.02) and peak power on take off on interaction (P = 0.04). For all other variables there was no significant (P > 0.05) unilateral retardation of the detraining effect for any of the kinetic variables for DJs or SLVJs following a nine week neuromuscular cross-education training programme. There were also no significant adaptations to the kinematic variables of KAM for either DJs or SLVJs.
Interpretation: There are clear kinetic differences between DJs and SLVJs primarily related to the utilisation of the stretch shortening cycle for DJs given the counter movement nature of the first landing and take off. Other differences include the key muscle groups and joint movements for force generation, which are specific to each jump type.
Clinical relevance: Cross-education adaptations for a contralateral limb are well established and there is an increasing interest in its potential use for rehabilitation purposes including the management of ACL injury risks.
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