Entrainment frequency of cardiolocomotor synchronization in distance running

This study tested the hypothesis that CLS in running spontaneous conditions would emerge at entrainment bands of muscle activation frequencies associated to free chosen step frequency. Sixteen male long-distance runners undertook treadmill assessments running ten three-minute bouts at different speeds (7, 7.5, 8, 9, 10,11, 12, 13, 14, and 15 km∙h-1). Electrocardiography and surface electromyography were recorded simultaneously. The centre frequency was the mean of the frequency spectrum obtained by wavelet decomposition, while CLS magnitude was determined by the wavelet coherence coefficient (WCC) between the electrocardiography and centre frequency signals. The strength of CLS affected the entrainment frequencies between cardiac and muscle systems, for WCC values greater than 0.8 the entrainment frequency was between 2.7-2.8 Hz.