Background Cross-education (CE) describes contralateral muscle function gain following unilateral limb training. CE has the potential to reduce strength and power losses following unilateral limb immobilisation. Despite the potential for wider rehabilitative application, few CE studies have utilised home-based interventions.

Objective Can unilateral home-based strength training elicit bilateral strength and power increases in the calf?

Design A prospective, randomised controlled trial utilising single-blinding.

Setting The Institute of Sport Exercise & Health, London

Participants Thirty-five healthy participants (21.0±1.5 years) with no resistance training 6 months prior to the study were recruited; thirty-four completed the study.

Intervention Participants were randomised to Intervention (n=20) or Control (n=15). Intervention completed 8 weeks of unilateral straight and bent-knee calf raises at-home, using resistance tubing. Load was self-progressed, sustaining a BORG CR10 score of seven.

Main Outcome Measurements Concentric and eccentric calf peak torque was measured using isokinetic dynamometry at 30°/s. Power output was measured during a single-leg jump using ChronoJump® (Chronojump-Boscosystem). Measurements were taken PRE, MID and POST-intervention.

Results The trained leg increased in strength PRE-POST for concentric (25.8±29.3%, p<0.01) and eccentric (19.5±17.8%, p<0.001) contractions. The untrained leg also increased in strength PRE-POST for concentric (20.5±25.6%, p<0.05) and eccentric (14.8±19.2%, p<0.05) contractions.

Power increased PRE-POST in the trained leg (19.3±4.1%, p<0.01). The untrained leg displayed PRE-POST power increases (18.8±3.4%, p<0.01). Controls displayed no significant strength or power changes.

In the untrained leg, strength increases were significant PRE-MID (16.3±16.9%, p<0.01) but not MID-POST (1.3±13.7%, p>0.05). The reverse was true for power with significant increases MID-POST (10.3±12.6%, p<0.01) but not PRE-MID (8.3±13.3%, p>0.05).

Conclusions This study demonstrates that unilateral, home-based strength training elicits significant bilateral calf strength and power increases. Additionally, the CE of strength seen prior to power indicates that outcomes secondary to the training type require greater training durations to reach significance. These findings may have rehabilitative potential, however further work is required in clinical populations.