Walking To A Fractal-like Stimulus Does Not Affect Cardiorespiratory Function
2020; Lippincott Williams & Wilkins; Volume: 52; Issue: 7S Linguagem: Inglês
10.1249/01.mss.0000683104.58619.23
ISSN1530-0315
AutoresStuart McCrory, Nelson Cortés, Lauren M. Biscardi, Navid Ghoddosi, Valdir A. R. Semedo, Joana F. Reis, João R. Vaz,
Tópico(s)Muscle activation and electromyography studies
ResumoGait complexity decreases with aging. Gait rehabilitation commonly uses step synchronization with external cues; yet, cues do not present variability in its structure. It has been recently suggested that cues should be presented in a fractal-like pattern (i.e., complexity). Yet, the effects of fractal-cueing on physiological outcomes remains poorly understood. PURPOSE: To investigate the effect of synchronization of visual stimulus with different temporal structures on cardiorespiratory function. METHODS: 14 male participants (23±4 yrs, 1.8±0.1 m, 70±9 kg) completed four 10-min treadmill walking trials at their preferred walking speed. First, self-paced walking (SPW) condition (no stimulus). Stride time from SPW was used to design individualized stimuli for 3 randomized cued conditions: periodic (PER), fractal (FRC), and random (RND). Detrended fluctuation analysis (DFA) was used to validate the temporal structure of the FRC and RND stimuli. The stimulus was provided via a moving horizontal bar projected on a screen. Heart rate (HR) and oxygen uptake (VO2) were collected. An accelerometer, placed at the ankle, was used to determine gait events. DFA was used to determine the fractal-scaling exponent from inter-stride intervals (ISIα). ANOVAs were conducted to assess differences between conditions for all dependent variables (p<0.05). RESULTS: Descriptive statistics are shown in Table 1. ISIα was significantly different between conditions (F2.44,31.70=33.76, p<0.0001). FRC and SPW had greater ISIα than PER and RND. CONCLUSION: FRC and SPW displayed higher complexity (ISIα) compared to PER and RND. Compared to SPW, only FRC maintained the complexity of the system. Participants maintained the structure of the stimuli. Notably, FRC appears a viable approach for gait training without altering the cardiorespiratory system, and likely improving gait complexity compared to the PER.Table 1.: Mean ± standard deviation of ISIα, VO2, and HR per condition
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