A Comparison of the Physiology of Sedentary Behavior and Light Physical Activity in Adults With and Without a Physical Disability.

BACKGROUND: It is questionable whether postures that are regarded as sedentary behavior in able-bodied persons evoke comparable physiological responses in adults with stroke or cerebral palsy (CP). This study aimed to compare metabolic demand and muscle activity in healthy controls, adults with stroke, and adults with CP during sedentary behavior and light physical activities. METHODS: Seventy-one adults (45.6 [18.9] y, range 18-86) participated in this study, of which there were 18 controls, 31 with stroke, and 22 with CP. The metabolic equivalent of task (MET) and level of muscle activation were assessed for different sedentary positions (sitting supported and unsupported) and light physical activities (standing and walking). RESULTS: During sitting supported and unsupported, people with mild to moderate stroke and CP show comparable MET and electromyographic values as controls. While sitting unsupported, people with severe stroke show higher METs and electromyographic values (P < .001), and people with severe CP only show higher METs compared with controls (P < .05) but all below 1.5 METs. Standing increased electromyographic values in people with severe stroke or CP (P < .001) and reached values above 1.5 METs. CONCLUSIONS: Physiologic responses during sedentary behavior are comparable for controls and adults with mild to moderate stroke and CP, whereas higher metabolic demands and muscle activity (stroke only) were observed in severely affected individuals.

Energy expenditure and muscle activity during lying, sitting, standing, and walking in people with motor-incomplete spinal cord injury.

STUDY DESIGN: Cross-sectional exploratory study. OBJECTIVES: To determine oxygen uptake (VO2), energy expenditure (EE), and muscle activity (MA) during lying (rest), sitting, standing, and walking among ambulatory individuals with spinal cord Injury (SCI) and to compare VO2, EE, and MA between individuals with different levels of ambulation. SETTING: Rehabilitation institution with a spinal cord injury unit. METHODS: A total of 22 adults with motor-incomplete SCI, ten in a low-ambulation group (non-functional or household walker) and 12 in a high-ambulation group (community or normal walker). VO2 was measured using indirect calorimetry. EE was expressed in metabolic equivalent of task (MET). MA was measured using a wireless surface electromyography device. RESULTS: Mean VO2 was 3.19 ml/kg/min. During lying and sitting, EE was below 1.5 METs for all participants. During standing, three participants of the low-ambulation group and none in the high-ambulation group showed MET values of >1.5. In the walking condition, all participants showed MET values above 1.5. MA during stance was higher compared to the sitting condition and significantly higher in the low-ambulation group compared to the high-ambulation group. CONCLUSION: Lying, supported- and unsupported sitting, without moving, appear to be sedentary behaviors for ambulatory individuals with a motor-incomplete SCI (MET values of <1.5 and a lack of MA). Walking, but not standing, is a moderate physical activity (>1.5 METs), which can be used by all individuals with motor-incomplete SCI to interrupt sedentary behavior.