Predicting peak oxygen uptake from submaximal exercise after spinal cord injury.

The purpose of this study was to determine the validity of the 6-min arm ergometry test (6MAT) in predicting peak oxygen consumption (V̇O2peak) in individuals with chronic spinal cord injury (SCI). Fifty-two individuals with chronic SCI (age, 38 ± 10 years; American Spinal Injury Association Impairment Scale (AIS), A-D; neurological level of injury (NLI), C1-L2; years post-injury (YPI), 13 ± 10 years) completed an incremental arm ergometry V̇O2peak test and a submaximal 6MAT. Oxygen consumption (V̇O2) data from both tests were used to create a predictive equation with regression analysis. Subsequently, a cross-validation group comprising an additional 10 individuals with SCI (age, 39 ± 13 years; AIS, A-D; NLI, C3-L3; YPI, 9 ± 9 years) were used to determine the predictive power of the equation. All participants were able to complete both the V̇O2peak and 6MAT assessments. Regression analysis yielded the following equation to predict V̇O2peak from end-stage 6MAT V̇O2: V̇O2peak (mL·kg(-1)·min(-1)) = 1.501(6MAT V̇O2) - 0.940. Correlation between measured and predicted V̇O2peak was excellent (r = 0.89). No significant difference was found between measured (17.41 ± 7.44 mL·kg(-1)·min(-1)) and predicted (17.42 ± 6.61 mL·kg(-1)·min(-1)) V̇O2peak (p = 0.97). When cross-validated with a sample of 10 individuals with SCI, correlation between measured and predicted V̇O2peak remained high (r = 0.89), with no differences between measured (18.81 ± 8.35 mL·kg(-1)·min(-1)) and predicted (18.73 ± 7.27 mL·kg(-1)·min(-1)) V̇O2peak (p = 0.75). Results suggest that 6MAT V̇O2 can be used to predict V̇O2peak among individuals with chronic SCI. The 6MAT should be used as a clinical tool for assessing aerobic capacity when peak exercise testing is not feasible.

Reliability and validity of the six-minute arm test for the evaluation of cardiovascular fitness in people with spinal cord injury.

OBJECTIVES: To design a submaximal arm ergometry test (six-minute arm test [6-MAT]), for persons with spinal cord injury (SCI) and to determine the test-retest reliability and concurrent validity of this test. DESIGN: Prospective, exploratory, methodologic study. To determine test-retest reliability, subjects completed the 6-MAT on 2 days, separated by 1 week. Validity was determined by comparing 6-MAT results with peak oxygen consumption (VO2peak). SETTING: Tertiary rehabilitation center. PARTICIPANTS: Thirty subjects with SCI (mean age, 36.3y; 83% male). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects were evaluated on the 6-MAT and a VO2peak test. RESULTS: All subjects were able to complete the 6-MAT. Test-retest reliability of steady-state oxygen consumption (VO2) and heart rate during the 6-MAT were excellent (intraclass correlation coefficient [ICC], .81; 95% confidence interval [CI], .58-.92; ICC=.90; 95% CI, .75-.96, respectively). The correlation between VO2peak and 6-MAT VO2 was excellent (r=.92) and the correlations between VO2peak and 6-MAT heart rate (r=.63) and VO2peak and 6-MAT power output (r=.73) were good. CONCLUSIONS: This study showed that the 6-MAT has acceptable values for test-retest reliability and validity. The 6-MAT should be further tested for responsiveness to enhance its use as a clinical tool.

Cardiovascular responses and postexercise hypotension after arm cycling exercise in subjects with spinal cord injury.

OBJECTIVE: To examine postexercise hypotension and contributing factors in subjects with spinal cord injury (SCI). DESIGN: Prospective clinical research study. SETTING: Rehabilitation center. PARTICIPANTS: Subjects with chronic cervical-level (n=19) and thoracic-level (n=8) SCI. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects underwent graded arm-cycling with electrocardiogram and oxygen uptake monitoring to exhaustion. Heart rates and blood pressures were measured before and after exercising. Injury to motor and sensory pathways was determined by American Spinal Injury Association grade, and to autonomic pathways by sympathetic skin responses (SSRs) (n=16). RESULTS: Resting blood pressures and heart rates were lower in cervical than thoracic SCI (mean arterial pressure [MAP]: cervical, 76.6+/-2 mmHg; thoracic, 93.5+/-3 mmHg; P<.001). Following exercise, heart rate responses were greater in thoracic than cervical SCI; MAP increased in thoracic SCI (8.4+/-5 mmHg) and markedly decreased in cervical SCI (-9.3+/-2 mmHg) (P<.001). No subject had significant electrocardiographic abnormalities at rest or during exercise. There were correlations between SSR and heart rate and blood pressure responses to exercise; the correlation between the SSR and blood pressure response was due to an interaction between the heart rate and blood pressure responses. CONCLUSIONS: Abnormal cardiovascular responses to exercise and transient postexercise hypotension were common in cervical, but not thoracic SCI. This may be partly related to loss of descending sympathetic nervous control of the heart and vasculature following high SCI.

Prevalence of shoulder pain in adult- versus childhood-onset wheelchair users: a pilot study.

Shoulder pain is a common overuse problem in long-term adult wheelchair users. The current study examined whether the prevalence of shoulder pain in adult wheelchair users who began using their wheelchairs during childhood (childhood-onset [CH-O] group) is similar to those who began using their wheelchairs as adults (adult-onset [AD-O] group). We compared 31 CH-O and 22 AD-O wheelchair users using the Wheelchair User's Shoulder Pain Index (WUSPI), an overall pain score (Brief Pain Inventory), and a lifestyle questionnaire to determine frequency and duration of physical activity. Shoulder pain (WUSPI) was greater in the AD-O wheelchair users compared with the CH-O group (p < 0.008), even though their general lifestyles were not different. The immature skeleton can possibly respond to the repetitive forces of wheeling better than that of those who begin using a wheelchair once their skeletal structure is completely developed.

A comparison of spinergy versus standard steel-spoke wheelchair wheels.

OBJECTIVES: To compare the energy efficiency of straight-line wheeling using Spinergy wheels as compared with standard steel-spoke wheels, and to assess the 2 wheels in terms of user comfort and wheeling preference during a wheeling course with multiple turns and surfaces. DESIGN: Nonblinded randomized crossover trial. SETTING: Rehabilitation center. PARTICIPANTS: Twenty persons with paraplegia (neurologic level T6 and below). INTERVENTION: Wheeling a straight line and obstacle course with Spinergy or standard spoke wheelchair wheels. MAIN OUTCOME MEASURES: Velocity and Physiological Cost Index (PCI) while wheeling over ground at a self-selected pace, and the User Preference Questionnaire after wheeling an obstacle course, using Spinergy or standard spoke wheelchair wheels. RESULTS: There was no significant difference in wheeling energy efficiency between the Spinergy and the steel-spoke wheels as measured by PCI ( P =.975). When rated for overall comfort, the Spinergy wheels were preferred over steel-spoke wheels ( P =.002). CONCLUSIONS: Spinergy wheels provided a more comfortable ride, but did not differ from standard steel-spoked wheels in terms of energy efficiency. The increased comfort may have important implications in patient management of pain and spasticity.