Although it is often stated that people with SCI are the most physically inactive segment of society, surprisingly few studies have actually measured physical activity in the SCI population. This lack of research is partly due to the fact that, until recently (Latimer et al., 2006a), there was no valid and reliable measure of physical activity for people with SCI that could be used in large-scale studies. Although several smaller studies (i.e., n < 50) have reported on physical activity levels among persons with SCI, given the considerable heterogeneity of the SCI population, the results of these studies are not necessarily generalizable. Thus, for the purpose of this review, we have focused only on larger-sample investigations.
Estimates of physical activity are affected by the approaches used to define and measure physical activity in a given study. In the reviewed studies, physical activity has been defined both narrowly (e.g., participation in sports activities), and more broadly to capture participation in all activities requiring physical exertion (e.g., leisure-time physical activity, activities of daily living), and even some “exercise” activities that are not at all exerting (e.g., relaxation exercises). With regard to measurement, all of the larger studies utilized self-report measures of physical activity, with considerable variability in the types and amounts of physical activity information collected. This information has ranged from simply the rate of participation in the sample, to more comprehensive data on the types of physical activities performed, and in some cases, participation frequency, duration, or intensity.
Physical activity participation rates have been reported in four studies — three Canadian, and one British. Notably, Martin Ginis and colleagues have reported results from a large cross-sectional study (n=695) based in Ontario, Canada designed to accurately measure the types, amounts, and intensities of LTPA (LTPA; defined as any physical activity that people choose to do during their spare time) performed by people with SCI (Martin Ginis et al. 2008; Martin Ginis et al. 2010a; Martin Ginis et al. 2010b). In these reports, which describe the methods and the baseline data from a prospective, longitudinal cohort study over 1.5 years, the initial overall participation rate was found to be 49.9% with these participants reporting a mean of 27.1 ± 49.4 minutes of LTPA a day, whereas 50.1% of participants reported no LTPA whatsoever (Martin Ginis et al. 2010a). Of those participants reporting >0 min/day of LTPA (n=347), there was a mean of 55.2 ± 59.1 min/day of LTPA at a mild intensity or greater with a median of 33.3 min/day (Martin Ginis et al. 2010b). Being male and greater than 11 years post-injury was associated with inactivity while having motor complete paraplegia and being a manual wheelchair user was associated with the most minutes of daily LTPA (Martin Ginis et al. 2010a). Although there was considerable variability among the activities preferred by individuals, most participants reporting LTPA did activities at a moderate level of intensity rather than mild or heavy and the 3 activities most frequently reported were resistance training, aerobic exercise and wheeling. The activities reported as being performed for the longest durations were craftsmanship and sports activities (Martin Ginis et al. 2010b).
In the other two Canadian studies (Buchholz et al. 2003; Carpenter et al. 2007), physical activity has been measured. Carpenter et al. (2007) reported that 75% of respondents participated in “fitness activities” which included breathing and relaxation exercises (i.e., activities that do not necessarily require physical exertion or have fitness-enhancing benefits). This physical activity participation rate is significantly higher than that reported by Buchholz et al. (2003). The authors found that only 56% of subjects engaged in physical activity. The British study (Tasiemski et al. 2005) defined physical activity as involvement in sports and reported participation rates of just 47%. The large between-studies differences in participation rates likely reflect the broader range of activities measured in the Carpenter et al. (2007) study (i.e., activities that are not typically considered physical activities).
Information beyond simple participation rates was reported in three studies (Buchholz et al. 2003; Latimer et al. 2006a; Tasiemski et al. 2005) in addition to the aforementioned information noted by Martin Ginis and colleagues (2010a, 2010b). Buchholz et al. (2003) reported that subjects engaged in physical activity 1.46±0.85 times during the study for a mean time of 49.4±31.0 minutes each session; additionally, the authors found that 76.4% of subjects were obese. Tasiemski et al. (2005) reported that the most commonly practised sports were swimming, archery, weight-training, basketball, and table tennis. Of those who were active, about half spent 3-6 hours/week engaged in sports and the remainder were active for < 2 hours/week. Latimer et al. (2006a) reported that on average, people with SCI spent 30 minutes/day engaged in LTPA and 213 min/day on activities of daily living that required at least mild intensity physical exertion. There was, however, tremendous variability in the amount of daily activity reported. Most of the LTPA was performed at mild and moderate intensities, and most of the activities of daily living were performed at a mild intensity. In general, men engaged in more LTPA than women, and younger people did more LTPA than older people. There were no differences in LTPA as a function of lesion level or completeness. It should be noted that the Latimer et al. (2006a) study was designed to validate a measure of physical activity for the SCI population (i.e., PARA-SCI) to be used in later larger-scale studies (i.e., Martin Ginis et al. 2010a; Martin Ginis et al. 2010b) rather than to measure LTPA in the SCI population. As a result, the study design and potential sampling biases may undermine the generalizability of their findings to the larger SCI population.
There is tremendous variability in the number of minutes of daily LTPA reported by persons with SCI. There is level 5 evidence from two large-sample studies and one small-sample study from different countries (i.e., Canada and UK) that approximately 50% of persons with SCI devote some time per week to sports, exercise, and other forms of LTPA.
There is level 5 evidence from a single study that a person with SCI participates in some form of LPTA for an average of about an hour per day (median ~ 30 minutes) when considering only the approximately 50% of people with SCI who are not inactive.
There is level 5 evidence from a single study that when physical activity is defined in terms of sports participation, the majority of people with SCI are considered inactive.
There is level 5 evidence from a single study that indicates that most daily physical activity is accumulated in the form of activities of daily living when physical activity is defined in terms of participation in any activity that requires physical exertion.