Purpose: Cycling muscle recruitment is less skilled in elite triathletes than in cyclists matched for cycling training history. This finding suggests that the multidiscipline training undertaken by triathletes interferes with adaptation of the neuromuscular system to cycling training in triathletes. The purpose of this study was to determine if similar interference with adaptation of the neuromuscular system would be evident during running in elite triathletes.
Methods: We compared intramuscular electromyographic (EMG) recordings from five muscles of the leg (tibialis anterior, tibialis posterior, peroneus longus, gastrocnemius lateralis, and soleus) during running at a controlled running speed between elite triathletes, runners matched to the triathletes for running training history (i.e., equally trained runners), and less-trained runners.
Results: Normalized EMG waveforms (i.e., time-series EMG data) were not different between groups, nor was EMG modulation (i.e., variations in EMG amplitude within strides). Individual variance (i.e., variability in muscle recruitment between strides for individual athletes) was greater for less-trained runners but was not different between elite triathletes and equally trained runners. Population variance (i.e., variability in muscle recruitment between athletes) was greater between less-trained runners for four of five muscles, but it was greater between elite triathletes than between equally trained runners for only two muscles.
Conclusion: We found no definitive evidence that running muscle activity is less skilled in elite triathletes than in equally trained runners. These findings are not consistent with our comparison of cycling muscle activity between elite triathletes and cyclists matched for cycling training history. Our findings suggest that multidiscipline training does not interfere with adaptation of running muscle activity in triathletes.