TPW 2.06 Exploring the Potential of Different Neuromuscular Electrical Stimulation Protocols to Optimise Early-Phase Muscle Rehabilitation after Colorectal Surgery

Abstract

Neuromuscular electrical stimulation (NMES) has been previously shown to attenuate muscle atrophy in the 5-days after colorectal surgery. However, if the protocol used was optimal in terms of intensity or time-under-tension remained unknown. Therefore, the aim of this study was to assess the effect of modified NMES protocols on acute muscle protein synthesis (MPS) in healthy volunteers age-matched to those commonly presenting for colorectal surgery. Eight older male volunteers attended 3 separate study visits each comprising a different 30-minute NMES protocol in a within-subject, randomised cross-over design. The protocols were: A) 30Hz, 1s on:1s off (original protocol); B) 100Hz, 1s on:1s off (increased intensity); C) 30Hz, 6s ON:2s OFF (increased time-under-tension). Myofibrillar MPS was assessed using a stable-isotope tracer technique. Effect size of interventions was compared using Cohen’s D. Mixed model analysis demonstrated no fixed effect of time or protocol, nor a time x protocol interaction. However, effect size analysis of before vs. after NMES for each protocol showed a moderate effect size for protocol A (+0.67), a small negative effect size for protocol B (-0.03), and a large effect size for protocol C (+0.87). Tolerability ratings were no different across the three protocols. Although there was no statistically significant difference between the three NMES protocols using mixed methods analysis, the observed effect size data indicates that NMES with prolonged time-under-tension may be the best strategy to optimally stimulate MPS, the physiological process required for muscle mass maintenance/hypertrophy. Further work is required to confirm this.