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Lin S-J1, Ababneh A1, Froehlich-Grobe K2, Cole M2
1Texas Woman's University, School of Physical Therapy, Dallas, Texas, United States, 2Baylor Scott & White Institute for Rehabilitation, Dallas, Texas, United States
Background: With the advances in medicine, life expectancy in individuals with spinal cord injury (SCI) has improved, yet cardiovascular comorbidities such as hypertension, obesity, diabetes, and coronary artery disease associated with a sedentary lifestyle in wheelchair-bound individuals with SCI are rising. Health benefits of regular exercise and physical activity are well documented. However, prior to engaging in regular exercise regimes, exercise testing in these individuals is important to ensure the safety and effectiveness of exercise training.
Purpose: The objectives of the study were to:
(1) assess exercise capacity,
(2) identify factors of exercise intolerance, and
(3) examine associations between exercise capacity and demographic factors in individuals with chronic spinal cord injury.
Methods: This is a cross sectional cohort study. A total of thirty-seven subjects (15 women and 22 men, age: 46±12 yrs, body weight: 85±24 kg; cervical spinal injury (11 subjects), thoracic spinal injury (25 subjects)) were enrolled. The inclusion criteria were: with SCI for at least 6 months, not participating in regular exercise in the past 3 months, with enough hand function to use an arm ergometer, and a physician referral. A metabolic graded exercise test interfaced with a 12-lead electrocardiography system was used. The test protocol involved a one-minute warm up and the two-minute stages of 5, 10, or 15 watts increment via an arm ergometer with the oxygen saturation being monitored via a forehead probe of a pulse oximeter. Each subject´s body weight was calculated by subtracting his/her wheelchair weight. Descriptive statistics was used for demographic factors. Pearson correlation analysis was conducted between age, body weight, body mass index, years post injury, and peak oxygen consumption (VO2peak) for the whole group and for each subgroup with a cervical or a thoracic spinal injury. Statistical significance was set at p 0.05.
Results: The average VO2peak values were low: 10.99 ± 3.56 (mL/kg/min) (the whole group), 9.07±2.62 (cervical injury group), 11.81±3.64 (thoracic injury group)). The reasons for test termination included muscle fatigue, dyspnea, respiratory exchange ratio >1.15, or arrhythmia. None of these subjects reached their predicted maximal heart rate. Subjects who developed arrhythmia during the exercise test were referred to their physicians for follow up. Only for the thoracic spinal injury group, the correlations between age and VO2peak, years post injury and VO2peak were significant (r= - 0.59, r= - 0.4 respectively), p 0.05.
Conclusion(s): These subjects showed moderately reduced exercise capacity typically seen in individuals with SCI and deconditioning. When the subjects were older, or when they had the spinal injury longer, their exercise capacities decreased further.
Implications: Metabolic graded exercise test in individuals with SCI and sedentary lifestyle may require monitoring of electrocardiography. Results of the study will serve as the basis for exercise prescription in these subjects. Innovative ways to promote engagement of regular exercise and/or physical activity in this population could not be over emphasized.
Keywords: spinal cord injury, graded exercise test, oxygen consumption
Funding acknowledgements: This is part of the WOWii study supported by the National Institute on Disability, Independent Living, and Rehabilitation Research (#901F0091-01-00).
Purpose: The objectives of the study were to:
(1) assess exercise capacity,
(2) identify factors of exercise intolerance, and
(3) examine associations between exercise capacity and demographic factors in individuals with chronic spinal cord injury.
Methods: This is a cross sectional cohort study. A total of thirty-seven subjects (15 women and 22 men, age: 46±12 yrs, body weight: 85±24 kg; cervical spinal injury (11 subjects), thoracic spinal injury (25 subjects)) were enrolled. The inclusion criteria were: with SCI for at least 6 months, not participating in regular exercise in the past 3 months, with enough hand function to use an arm ergometer, and a physician referral. A metabolic graded exercise test interfaced with a 12-lead electrocardiography system was used. The test protocol involved a one-minute warm up and the two-minute stages of 5, 10, or 15 watts increment via an arm ergometer with the oxygen saturation being monitored via a forehead probe of a pulse oximeter. Each subject´s body weight was calculated by subtracting his/her wheelchair weight. Descriptive statistics was used for demographic factors. Pearson correlation analysis was conducted between age, body weight, body mass index, years post injury, and peak oxygen consumption (VO2peak) for the whole group and for each subgroup with a cervical or a thoracic spinal injury. Statistical significance was set at p 0.05.
Results: The average VO2peak values were low: 10.99 ± 3.56 (mL/kg/min) (the whole group), 9.07±2.62 (cervical injury group), 11.81±3.64 (thoracic injury group)). The reasons for test termination included muscle fatigue, dyspnea, respiratory exchange ratio >1.15, or arrhythmia. None of these subjects reached their predicted maximal heart rate. Subjects who developed arrhythmia during the exercise test were referred to their physicians for follow up. Only for the thoracic spinal injury group, the correlations between age and VO2peak, years post injury and VO2peak were significant (r= - 0.59, r= - 0.4 respectively), p 0.05.
Conclusion(s): These subjects showed moderately reduced exercise capacity typically seen in individuals with SCI and deconditioning. When the subjects were older, or when they had the spinal injury longer, their exercise capacities decreased further.
Implications: Metabolic graded exercise test in individuals with SCI and sedentary lifestyle may require monitoring of electrocardiography. Results of the study will serve as the basis for exercise prescription in these subjects. Innovative ways to promote engagement of regular exercise and/or physical activity in this population could not be over emphasized.
Keywords: spinal cord injury, graded exercise test, oxygen consumption
Funding acknowledgements: This is part of the WOWii study supported by the National Institute on Disability, Independent Living, and Rehabilitation Research (#901F0091-01-00).
Topic: Neurology; Cardiorespiratory; Health promotion & wellbeing/healthy ageing
Ethics approval required: Yes
Institution: Texas Woman's University (TWU) and Baylor Research Institute
Ethics committee: TWU and Baylor Institutional Review Boards
Ethics number: protocol # 19442
All authors, affiliations and abstracts have been published as submitted.
