Effects of arm cranking exercise on muscle oxygenation between active and inactive muscles in people with spinal cord injury

• Published in: The journal of spinal cord medicine Vol. 44; no. 6; pp. 931 - 939
• Main Author: Horiuchi, Masahiro
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 02.11.2021
• Subjects: Arm; Autonomic Dysfunction; Blood Flow; Exercise Therapy - methods; Extraction; Heart Rate; Humans; Muscle, Skeletal; Oxygen Consumption - physiology; Spinal Cord Injuries; Sympathetic Vasoconstriction; Heart Rate; O2 Extraction; Sympathetic Vasoconstriction; Blood Flow; Autonomic Dysfunction
• ISSN: 1079-0268; 2045-7723; 2045-7723
• DOI: 10.1080/10790268.2020.1754649

Objective: We investigated the effects of the incremental arm-cranking exercise (ACE) on tissue oxygen saturation (StO 2 ) between active and inactive muscles, and the relationship between peak oxygen uptake (VO 2peak ) and changes in the StO 2 in inactive muscles. Design: Observational study. Setting: Community-based supervised intervention. Participants: The participants were individuals with motor and sensory complete spinal cord injury (complete SCI; n = 8) and motor complete but sensory incomplete SCI (incomplete SCI; n = 8), and able-bodied (AB) individuals (n = 8) matched for age, height, and body mass index. Intervention: The ACE was performed at a rate increasing by 10 watts min −1 until exhaustion. Outcome Measures: VO 2peak , heart rate (HR), and StO 2 . Results: While VO 2peak was similar among the groups, peak HR was significantly higher in both SCI groups than in the AB (P < 0.05). In active muscles (biceps brachii), no differences in the StO 2 were observed among the groups (P > 0.05). In inactive muscles (vastus lateralis), the StO 2 in the AB and the incomplete SCI began to decrease at approximately 40% of the peak work rate; however, they remained unchanged in the complete SCI. The reductions in StO 2 in the AB were significantly greater than in the incomplete SCI. Conclusions: These results suggest that sympathetic vasoconstriction occurred in the incomplete SCI and AB, although it did not occur in the complete SCI, probably due to a reduction in sympathetic nerve activity. Sympathetic vasoconstriction in inactive muscles may not contribute to an individual's VO 2peak regardless of their group.