Feasibility of a Sprint Interval Training Program During Inpatient Spinal Cord Injury Rehabilitation

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Physical inactivity is a major problem facing people with SCI. In chronic SCI, about 50% of people engage in no leisure time physical activity. That is, they do not wheel or walk for pleasure, do not play a sport, and do not exercise at home or go to a gym. Approximately 1 in 4 healthy young persons with SCI lack sufficient physical fitness to perform many essential activities of daily living. Becoming physically inactive harms physical and mental health and reduces quality of life after SCI. Physical inactivity leads to a downward spiral of loss of muscle mass, decreased resting energy expenditure, decreased total energy expenditure, obesity and further loss of muscle mass in people with disabilities including SCI. Physical inactivity is associated with an increased risk of cardiovascular disease, obesity, dyslipidemia, diabetes, and hypertension in SCI. Low physical activity (PA) is also associated with depression, chronic pain and fatigue after SCI. Many studies demonstrate an association between physical inactivity and poorer quality of life. Current evidence-based exercise guidelines recommend that, "for cardiorespiratory fitness and muscle strength benefits, adults with a SCI should engage in at least 20 min of moderate to vigorous intensity aerobic exercise 2 times per week AND 3 sets of strength exercises for each major functioning muscle group, at a moderate to vigorous intensity, 2 times per week." A large body of research demonstrates that following these guidelines increases cardiovascular fitness, power output, and muscular strength in chronic SCI. Exercise training reduces low-density lipoprotein (bad) cholesterol, increases high-density lipoprotein (good) cholesterol in chronic SCI and improves insulin sensitivity. Most importantly for this study, increased exercise or PA is associated with improved depression, diminished pain, and better quality of life in people with chronic SCI. Despite these promising results, research-based exercise programs for people with SCI have limited impact on this population. For example, intervention studies reach few patients. On average, only 42% of people who are eligible enroll in SCI exercise studies and the mean sample size is just 24 participants. Exercise research has focused almost exclusively on people with chronic SCI, after patterns of physical inactivity have become entrenched. Outside of research studies, people with SCI face numerous barriers to exercise. While 86% of non-exercisers desire to exercise, they face poor access to exercise facilities, limited transportation, or not having exercise equipment at home. Possibly as a result of having limited experience with exercise and falling into a sedentary lifestyle, individuals with SCI often develop perceptions about exercise that are barriers such as the belief that exercise is not enjoyable, it is too difficult, it will worsen their condition, or not knowing how to exercise. Inpatient rehabilitation and the post discharge period is a missed opportunity to promote exercise. In the United States (U.S.), inpatient rehabilitation (IPR) currently provides little exposure to cardiovascular challenging exercise due to short duration of stay and a primary focus on achieving functional independence. During the first six months after discharge from IPR, PA generally declines and body mass increases which begins the downward spiral described above. Yet, only 10% of exercise-based studies in SCI were conducted during the first year after SCI. The investigaors think IPR is a window of opportunity to promote exercise and adoption of an active lifestyle as people are learning to live with SCI. Researchers in the Netherlands and Canada have utilized IPR and post-IPR to promote adapted exercise habits. A prior study using interval training with handcycling during the last eight weeks of IPR showed that this form of PA is feasible and improved physical capacity. A subsequent study by the same group examined whether a handcycling program during IPR combined with motivational interviewing (MI) to increase the amount of wheeled PA each day was more effective than handcycling alone. Results reported that the group that received MI demonstrated 28 and 25 minutes more wheeled PA per day at six and 12 months post discharge relative to the handcycle only group. A recent study evaluated the feasibility and preliminary efficacy of a time efficient form of interval training during IPR. Sprint interval training (SIT) was completed in 10-minute sessions three times per week for 5 weeks. Data showed that SIT could be integrated into IPR and it produced similar effects on physical capacity that were comparable to a control group that completed traditional aerobic exercise, 75 minutes per week. In addition, a randomized controlled study in the Netherlands showed that adding MI to interval training during IPR increases PA through six months post-discharge. While SIT appears to be a promising intervention to enhance physical capacity during IPR, and MI has potential to produce higher levels of wheeled PA after discharge, both interventions were performed in countries with much longer rehabilitation lengths of stay (LOS) than in the U.S. Whereas the median IPR LOS for people with SCI is approximately 35 days in the U.S., the mean LOS in the Netherlands and Canada is 227 days and 84 days, respectively. Therefore, it is uncertain whether SIT and MI are feasible and can be effective in the U.S. because IPR LOS is much shorter than in these countries. There is an urgent need to examine whether it is feasible to integrate SIT and MI into IPR in the U.S. and to determine whether these intervention components can lead to increased physical activity related psychosocial benefits after discharge from the hospital. Otherwise, our rehabilitation programs will continue to discharge patients who are often unprepared to be physically active and who will adopt a sedentary lifestyle with the attendant adverse physical and psychosocial consequences. The investigators hope that by exposing individuals with acute SCI to more efficient and effective means of exercising during IPR, they will become more physically active and reap the benefits of a more active lifestyle, that is, better mental health, physical health, and quality of life. This study also addresses critical service gaps in the U.S. model of IPR by educating participants in how to perform a SIT program and providing some with an ergometer to continue the program at home. Furthermore, the addition of motivational interviewing in one arm of the study design also seeks to increase understanding of psychological factors that affect participation in and adherence to this novel exercise program. This line of research has the potential to initiate important changes in practice during IPR and in insurance funding. If SIT ultimately improves physical fitness, PA, and related indicators of health, then the scientific community will have evidence to advocate for inclusion of SIT as a standard aspect of IPR covered by U.S. insurance companies. Additionally, if having a home arm ergometer leads to better cardiovascular health and PA adherence, the investigators will possess scientific evidence to help advocate for insurance companies to cover these devices for patients.