Alterations in step frequency and muscle activities using body weight support influence the ventilatory response to sinusoidal walking in humans

• Published in: Scientific reports 2023-09, Vol.13 (1), p.15534-15534, Article 15534
• Main Authors: Fujita, Mako, Kamibayashi, Kiyotaka, Horiuchi, Masahiro, Ebine, Naoyuki, Fukuoka, Yoshiyuki
• Format: Article
• Language: English
• Subjects: 631/443; 704/172; Body measurements; Body weight; Carbon dioxide; Electromyography; Fourier analysis; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary); Skeletal muscle; Ventilation; Ventilatory behavior
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-42811-w

The use of body weight support (BWS) can reveal important insights into the relationship between lower-limb muscle activities and the ventilatory response during sinusoidal walking. Here, healthy participants (n = 15) walked on a treadmill while 0%, 30%, and 50% of their body weight was supported with BWS. The walking speed was varied sinusoidally between 3 and 6 km h −1 , and three different frequencies, and periods ranging from 2 to 10 min were used. Breath-by-breath ventilation ( V ˙ E ) and CO 2 output ( V ˙ CO 2 ) were measured. The tibialis anterior (TA) muscle activity was measured by electromyography throughout the walking. The amplitude ( Amp ), normalized Amp [ Amp ratio (%)], and phase shift ( PS ) of the sinusoidal variations in measurement variables were calculated using a Fourier analysis. The results revealed that the Amp ratio in V ˙ E increased with the increase in BWS. A steeper slope of the V ˙ E – V ˙ CO 2 relationship and greater V ˙ E / V ˙ CO 2 values were observed under reduced body weight conditions. The Amp ratio in TA muscle was significantly positively associated with the Amp ratio in the V ˙ E (p