Many authors have noted the importance of participation in physical activity and exercise programming for persons with spinal cord injury (SCI) and several of these have provided reviews of the various purported benefits that may occur with regular and appropriate physical activity (Cowell et al. 1986; Washburn & Fignoni 1999; Jacobs & Nash 2001; Nash 2005; Devillard et al. 2007; Fernhall et al. 2008). Despite this assertion and the relative plethora of studies cited within these reviews, especially in some areas (e.g., cardiovascular fitness), there is much that remains to be established about the relationship of exercise and physical activity to the health and well-being of persons with SCI. It has been noted that the majority of physical activity studies are often lower quality with few randomized controlled trials (RCTs) (Valent et al. 2007; Fernhall et al. 2008), which is not surprising as exercise studies are challenging to conduct in and of themselves and this is compounded by multiple further challenges that are presented within the SCI population (Ginis & Hicks, 2005). Little is known about the details of what exercise modality might be best suited for individuals with SCI relative to their varying physical levels of function. Specific information about frequency, intensity and duration is typically lacking. In general, there is a dearth of evidence-based information on which to provide guidance for the promotion and prescription of exercise, especially for the various subsets of individuals that comprise this population (Ginis & Hicks 2007; Myslinski 2005).
The present chapter aims to describe the level of evidence that exists for physical activity and its effect on various aspects of health and wellness for persons with SCI. In particular, we review the evidence that exists for the effectiveness of physical activity on enhancing strength, muscle function, rehabilitation recovery (i.e., functional outcomes) and subjective well-being (including depression and quality of life) as well as the relationship of physical activity to the prevention and minimization of various secondary complications and other health conditions associated with SCI. Following this, we examine the studies that assess the rates of physical activity participation and identify barriers to participation noted in the literature. Finally, we describe the level of evidence associated with interventions targeted at persons with SCI designed to enhance participation in physical activity.
SCI impacts many body systems both immediately and in the long-term as noted in numerous reviews (Bauman et al. 1999; Shields 2002; Nash 2005). In particular, Nash (2005) and Jacobs and Nash (2004) point to physical deconditioning across the musculoskeletal system (i.e., bone, muscle and joint) and alterations in both cardiac and peripheral vascular structure and functioning in persons with SCI. These issues, when combined with continued inactivity, result in seemingly inevitable body system decline and are linked to the increased incidence of various secondary complications and other health conditions associated with SCI such as cardiovascular disease, respiratory complications, osteoporosis, pain, spasticity and diabetes. Evidence for routine physical activity has been noted as an important factor in maintaining health and wellness and preventing many of these conditions in the able-bodied population and in those with chronic disease such as arthritis (US Department of Health and Human Services 1996; Warburton et al. 2006; Kruk 2007). However, the evidence linking health and physical activity in persons with SCI or similar conditions is far from established, despite the importance placed on physical activity by clinicians, consumers and researchers alike in optimizing recovery and maintaining health (Rimmer 1999; Anderson 2004; Fernhall et al. 2008).
In reviewing the literature associated with various physical activity and exercise interventions in SCI, it was apparent that the vast majority of studies examine physiological parameters (e.g., VO2, cardiovascular responses to exercise) that would be characterized as relating to body function and structure within the framework of the International Classification of Functioning, Disability and Health (ICF). We do not report here the numerous studies that address these physiologic outcome measures other than to note the various conclusions made surrounding specific risk factors associated with the development of cardiovascular disease or other health conditions. There is a relative dearth of studies examining the effect of physical activity interventions on functional outcomes, especially those that might be characterized as measures of activity or participation (as per the ICF). This suggests a target for future research in elucidating either the functional consequences or societal participation benefits associated with physical activity interventions for persons with SCI.
It should be noted that while one of the aims of this chapter is to bring the information about physical activity and SCI into one place, most of these topic areas comprise individual chapters with SCIRE. Therefore, when there may be substantial duplication with an existing SCIRE chapter we have selected to simply reference the existing chapters that contain information about physical activity interventions and to also bring forward the conclusions (evidence statements and bottom-line conclusions) from these chapters so the reader will gain a sense of the degree of evidence across these various conditions. The reader is encouraged to examine the referenced chapter for surrounding discussion and more information concerning the various studies and details about the specific interventions comprising the evidence. Of note, many of the therapies associated with upper limb or lower limb management involve therapeutic exercise programming (often associated with physical or occupational therapy) and for these we simply refer the reader to SCIRE Chapter’s: Upper Limb Rehabilitation Following Spinal Cord Injury (Connolly et al. 2010) and Lower Limb Rehabilitation Following Spinal Cord Injury (Lam et al. 2010) respectively. This has meant that the conclusions related to specific rehabilitation interventions (e.g., Body weight supported treadmill training, FES upper and lower limb applications) may not be comprehensive within the present chapter, but should be augmented by those from the noted chapters.
The following section describes the evidence for physical activity as an intervention directed towards persons with SCI in enhancing strength, muscle function, rehabilitation recovery (i.e., functional outcomes) and subjective well-being (including depression and quality of life) as well as in preventing or minimizing common secondary conditions typically encountered following SCI. These include the role of physical activity in maintaining or enhancing cardiovascular health and bone health as well as preventing or mitigating disability associated with respiratory complications, pain, spasticity and periodic leg movements.
Even though the most visible aspect of SCI involves impaired muscle function ranging from slight weakness to complete paralysis, there is far more research addressing aerobic training than pure resistance training for enhancing strength, endurance and other aspects of muscle function (Jacobs and Nash 2004). The effects of aerobic exercise on aerobic capacity will be summarised in a subsequent section that is focused on cardiovascular health. The present section describes the effects of various forms of exercise (i.e., not only pure resistance training but also those that incorporate the more frequently implemented endurance training as well) and the various adaptations that result in muscle. These adaptations are characterized as those pertaining to muscle morphology or muscle function. Muscle morphological changes in response to appropriately configured physical activity interventions are reflected in such outcomes as overall changes to muscle cross-sectional area (i.e, direct or indirect measures such as limb circumference) or in changes to individual muscle fibres as reflected by changes in individual muscle fibre size or fibre type. Changes in muscle function are often assessed by direct measurement of muscle strength or power output or might be reflected in muscular endurance (i.e., exercise capacity changes) such as that seen in the ability to manage greater loads over a longer period of time during a progressive exercise program.
Table: Physical Activity and Adaptations to Muscle Morphology and Strength
A variety of benefits related to gross muscle morphology have been demonstrated in numerous investigations employing multi-week progressive exercise programs of FES-assisted cycling in which lower limb muscles (i.e., typically quadriceps, hamstrings and gluteal muscles) are stimulated to produce cycling movements against resistance (Sloan et al. 1994; Hjeltnes et al. 1997; Mohr et al. 1997; Chilibeck et al. 1999; Scremin et al. 1999; Crameri et al. 2004; Heesterbeek et al. 2005; Griffin et al. 2009). Each of these FES-assisted cycling programs consisted of a minimum of three 30 minute sessions per week with program duration ranging from 8 weeks to 1 year with progressive resistance customized to the individual participant. Of note, Heesterbeek et al. 2005 employed a hybrid FES-assisted cycling protocol in which upper limb cycling was also incorporated into the physical activity intervention and Scremin et al. 1999 had a 4 phase intervention in which the final phase consisted of adding upper limb ergometry to FES-assisted lower limb cycling. These were the only investigations that incorporated upper body exercise although outcome measurement was limited to the muscles of the lower limb. All studies, other than that conducted by Crameri et al. 2004, were uncontrolled investigations incorporating either a prospective pre-post or retrospective case series study design. In addition, all of the studies were relatively small with sample sizes of 18 persons or less. Benefits to gross muscle morphology consisted of significant increases in total body lean muscle mass (Griffin et al. 2009), thigh muscle mass (Mohr et al. 1997), cross-sectional area of overall thigh muscle (Sloan et al. 1994; Hjeltnes et al. 1997, Scremin et al. 1999) and overall thigh volume (Heesterbeek et al. 2005) as well as significant reductions in muscle atrophy (Mohr et al. 1997). Significant increases were also seen in overall cross-sectional area or mean muscle fibre cross-sectional area within individual muscles (Chilibeck et al. 1999; Scremin et al. 1999; Crameri et al. 2004).
Other forms of neuromuscular electric stimulation resistance exercise training have also been shown to produce beneficial muscle adaptations. In a relatively large study, persons with complete denervation due to a conus or caudal lesion (n=20 completing) underwent a 2 year home-based progressive electrical stimulation program which culminated in 30 minute sessions, 5 days/week involving a combination of twitch and tetanic stimulation patterns focusing on quadriceps but also on gluteal, hamstring and other lower limb muscles (Kern et al. 2010). Quadriceps and hamstring muscle cross-sectional areas were significantly larger with training with these results being more pronounced for the quadriceps. Similarly, significant increases in quadriceps muscle cross-sectional areas were produced in 5 males with ASIA A SCI with a home-based, two day/week program over twelve weeks in which four sets of ten unilateral, dynamic knee extensions were elicited by appropriate stimulation (Mahoney et al. 2005). A later report extended these observations with similar results following 18 weeks (Sabatier et al. 2006).
Other modes of endurance-based resistance exercise also led to similar muscle adaptations. For example, sustained participation in body weight support treadmill training 2 or 3 times/week resulted in significant increases in overall muscle cross-sectional areas in the thigh and lower leg muscles (Giangregorio et al. 2005; Giangregorio et al. 2006; Carvalho et al. 2008)as well as increases in mean individual muscle fibre sizes (Stewart et al. 2004) and partial reversal of muscle atrophy (Giangregorio et al. 2006). Of note, Carvalho et al. 2008; Carvalho et al. 2009 conducted a controlled trial (n=15) which showed significantly greater increases in MRI-derived quadriceps cross-sectional area with neuromuscular stimulation combined with body-weight supported treadmill gait training as compared to that seen with conventional physiotherapy. This was conducted over a 6 month period after which the gait training was offered to the control group. Gait training sessions consisted of 20 minute sessions at a frequency of twice/week.
To this point, of all studies noted in this section, each of the interventions were applied to individuals with chronic SCI (i.e., > 6 months post-injury) with the exception of Giangregorio et al. 2005 who performed body weight support treadmill training on those more newly injured (i.e., 2-6 months post-injury). In addition, across studies participants had mostly complete or in rare instances near-complete SCI (i.e., AIS A, B or C).
A novel methodology was employed by Crameri et al. 2004 to investigate the effects of load on these types of muscle adaptations. These investigators used a forty-five minute/day, three day/week FES-assisted cycling exercise protocol over ten weeks in which only one leg of each study participant was permitted to cycle against minimal load. The contralateral leg was also provided similar stimulation parameters as the “cycling” leg but these were applied against a fixed load so as to provoke rhythmic isometric contractions of the quadriceps and hamstrings against resistance. Exercise progressions were implemented with increases to the work-rest cycle and not to resistance as is often done in trials of FES-assisted cycling ergometry. This controlled investigation demonstrated that the amount of resistance is important in producing a training effect as greater increases in isometric force generation and muscle fibre cross-sectional area were demonstrated for the static, high-resistance training condition.
Additionally, muscle biopsies have been performed before and after training, permitting investigation of the effects of physical activity on fibre type. Following SCI, (especially in those with complete or near complete lesions), there is an established transformation of muscle fibres away from type IIa toward type IIx fibres reflecting a functional shift towards less aerobic, more easily fatigable muscle (Grimby et al. 1976; Round et al. 1993). This shift was reversed over ten weeks (Crameri et al. 2002) and also at 6 months of a 1 year program (Andersen et al. 1996) of three day/week FES-assisted cycling exercise and with six months of three day/week body weight-supported treadmill training (Stewart et al. 2004) as each of these studies reported an increase in type IIa fibres and a corresponding reduction in type IIx (or IIb) fibres following training. More interestingly, similar results were seen in Crameri et al. 2004’s investigation of the effect of static load vs. dynamic minimal load conditions with shifts of type IIx to type IIa muscle fibres apparent for both conditions along with the additional finding of a significantly greater increase in type I fibres only for the static, high-resistance trained leg. This represents an even more dramatic adaptation toward the aerobic, oxidative capacity of muscle with this type of training. Kern et al. 2010 demonstrated similar findings with their home-based neuromuscular stimulation promotion with increases in muscle fibre size that reverses the atrophic processes noted in denervated muscle.
There is also some evidence that passive cycling using upper-body assistance to drive paralyzed leg muscles involving 2 day/week sessions over 12 weeks may be sufficient to prevent these inactivity-related shifts towards more “fast” type muscle fibers. Willoughby et al. 2000 demonstrated significant increases in mRNA expression for type IIa fibres (and also for type IIx fibres) in the presence of decreasing proteolytic activity typically associated with muscle degradation. This passive exercise was insufficient to produce a significant increase in muscle size as indicated by no change in thigh girth and it is important to note that the leg movement required upper body voluntary exercise.
In contrast to those investigations assessing outcomes related to muscle morphology, those assessing strength or muscular endurance were much more diverse with respect to the exercise modes employed. Notably, five investigators incorporated RCT study designs (Needham-Shropshire et al. 1997; Hicks et al. 2003; Hartkopp et al. 2003; Glinsky et al. 2008; Jacobs 2009) despite the acknowledged difficulty in fully implementing such features as participant blinding with the physical activity interventions typically associated with this design (Ginis and Hicks 2005).
Of these RCTs, four of five trials resulted in statistically significantly increases in strength, although there were different training paradigms used to achieve these results across the trials. Needham-Shropshire et al. 1997 used a paired-randomization approach to assign subjects with chronic cervical SCI (n=27) to one of three groups:1) those receiving 8 weeks of neuromuscular stimulation-assisted arm ergometry exercise (NMS); 2) those receiving 4 weeks of NMS assisted exercise followed by 4 weeks of voluntary arm crank exercise; and 3) those participating in a control condition – voluntary exercise for 8 weeks without the application of NMS. Muscle strength was assessed by manual muscle testing in the triceps and the largest treatment effect (i.e., more muscles showing an increase of at least one muscle grade) was seen in Group 1 subjects (p<0.0005) although there were also a significant number of muscles that demonstrated an increase in muscle grade in Group 2 (p<0.03) relative to the control condition. In a pre-post study, Cameron et al. (1998) used a prototype of the NMS-assisted arm crank ergometer used by Needham-Shropshire et al. 1997 to elicit significant improvements to triceps muscle strength following a three days/week upper body training program conducted over eight weeks.
These results are consistent with those reported by Hicks et al. 2003 who conducted an RCT (n=34, with 11 of 21 completing in the exercise group) of a twice weekly progressive voluntary arm ergometry cycling and resistance training exercise.program with sessions of 90-120 minutes over nine months. These investigators noted significant increases (p<0.05) in muscle strength for 3 different upper body maneuvers involving triceps, biceps and anterior deltoid bilaterally at nine months as compared to baseline, although these increases in muscle strength showed progressive improvement over the nine months.
Jacobs (2009) compared a resistance training paradigm involving 3 sets of 10 repetitions across six stations at 60-70% of a maximal single effort vs endurance training for 30 minutes involving arm cranking at 70%-85% of peak HR in persons with neurologically complete paraplegia (n=18). There were 3 sessions/week over a 12-wk training period with standardized exercise progressions for both the resistance training and endurance training groups and participants were matched between groups by body mass and gender. Muscular strength was significantly increased (p<0.01) with resistance training for each of the 6 isotonic strength testing maneuveurs corresponding to those involved for each of the resistance training stations. There were no strength changes apparent for those in the arm ergometry group (i.e., endurance training). However, muscular endurance, as indicated by performance on the Wingate anaerobic power test, was significantly improved with both forms of training, although these improvements were most pronounced with resistance training.
The RCT conducted by Glinsky et al. 2008 failed to show statistically significant increases in strength or muscular endurance (i.e., fatigue resistance) in wrist extensor or flexor muscles that were at least partially paralyzed in persons with tetraplegia (n=32). There was an overall mean increase of 8% and 11% in strength and muscular endurance respectively with training vs no training groups but this was deemed clinically insignificant. This study involved a resistance training program involving 3 sets of 10 repetitions using a customized device that permitted those with even minimal force generation to participate in a progressive exercise program. These authors noted that unlike other trials (e.g., Hicks et al. 2003), all participants had at least some paresis although it should be noted that there was a slight imbalance between experimental (i.e., training) vs control (i.e., no training) groups with respect to a slightly greater impairment in participants in the training group (i.e., 9 vs 6 persons with ASIA A and 4 vs 0 persons with an initial muscle grade of 2).
A similar training system to that employed by Glinsky et al. 2008 was used by Hartkopp et al. 2003 to examine the effect of electrical stimulation on strength and fatigue resistance in wrist extensor musculature in persons with tetrapegia (n=12 completing trial). This RCT used the nontrained arm as a control and demonstrated significant strength gains with a high resistance protocol, but not a low resistance protocol – each involving 5, 30 min sessions/week over 12 weeks. The high resistance protocol consisted of stimulation against a maximal load, whereas the low resistance protocol used a resistance of 50% of maximal load. Both training protocols were effective in improving resistance to fatigue.
There were also several investigations involving mostly pre-post study designs resulting in improved muscle function with different forms of electrically-stimulated exercise. For example, FES-assisted cycling programs involving the lower limbs and of varying durations and frequencies have demonstrated beneficial effects on muscle function. Griffin et al. (2009) demonstrated improved ASIA motor (and sensory scores) for the lower extremity following FES cycling for 2-3 times per week over 10 weeks in a group of persons with mostly incomplete SCI from C4-T7 (i.e., 13 of 18 with incomplete SCI). In persons with complete chronic SCI, FES-assisted cycling is effective for improving resistance to muscular fatigue as indicated by increases to sustained torque generation with repetitive stimulation in programs employing as little as 3, 30 min sessions/week over 6 weeks (Gerrits et al. 2000). A more extensive long-term program involving 5, 1 hour sessions/week over 1 year also was effective in improving fatigue resistance as well as producing a fivefold increase in maximal electrically stimulated torque (i.e., strength of contraction), although this remained lower than in able-bodied individuals (Duffell et al. 2008). Interestingly, in a later study, Gerrits et al. 2002 demonstrated that fatigue resistance was improved more effectively by low frequency (i.e., 10 Hz) vs high frequency (i.e., 50 Hz) stimulation, although each was equally effective in improving force generation (i.e., tetanic tension development).
In addition, several investigators have employed other approaches to lower limb neuromuscular stimulation such as the long-term home-based stimulation program by Kern et al. (2008) which resulted in a near ten-fold increase in stimulation-elicited muscle force in addition to the benefits to muscle morphology noted above. Sabatier et al. 2006 conducted a smaller pre-post study (n=5 persons with complete SCI) of an eighteen week home-based neuromuscular electrical stimulation resistance training program involving bi-weekly quadriceps training comprised of four sets of 10 dynamic knee extensions against resistance while in a seated position. This resulted in significant increases in strength (i.e., weight lifted), as well as a 60% reduction in muscle fatigue (p = 0.001).
Given the results of these studies, it is clear that there are a variety of approaches involving neuromuscular stimulation to the lower limb that accrue benefits to muscle function. However, information regarding the minimum requirements with respect to frequency, intensity, duration of a training program and how each of these might interact with different patient subgroups remains to be definitively established. Interestingly, Petrofsky et al. 2000 conducted a study to assess the effect of altering various parameters associated with a ten week training program of quadriceps muscle stimulation. These investigators assigned subjects (n=90) to 10 different treatment groups and examined the effect of altering some of the parameters associated individual treatment sessions. Greater strength changes were seen for 30 minute sessions as compared to 5 or 15 minute sessions and for 3 day/week training as compared to 1 or 5 day/week training programs. In addition, strength gains and total work capacity was optimized by incorporating a pattern of 3 s extension - 3 s flexion – 6 s rest as compared to longer or shorter durations of work-rest cycles.Several investigations of voluntary exercise employing pre-post study designs have demonstrated strength benefits (in addition to other benefits). These studies have been conducted mostly in persons with paraplegia and have included circuit resistance training for 3 days/week (Durán et al. 2001; Jacobs et al. 2001; Nash et al. 2007), a combination of resistance training and plyometric training (Gregory et al. 2007) and 3, 60 minute sessions/week of kayak ergometer training over 10 weeks (Bjerkefors et al. 2006).
As demonstrated in the previous section, appropriately configured exercise has been demonstrated to increase muscle strength and reduce atrophy. Most rehabilitation professionals presume there is also a clear link between therapeutic exercise and functional improvement that might manifest in enhanced performance of activities of daily living (ADLs). The present section examines the literature that assesses the functional consequences of physical activity programming. As described in of SCIRE Chapter: Rehabilitation Practices (Wolfe et al. 2010), there are numerous reports of substantial gains achieved over the period of inpatient rehabilitation for outcome measures associated with functional independence (e.g., Functional Independence Measure (FIM(TM))) but the definitive attribution of these gains to specific aspects of rehabilitation programming remains to be fully elucidated.
Table: Physical Activity and Functional Improvement Including ADLs
Of the interventional studies noted in Table 2, only four could be described as examining functionally-based outcome measures as a primary measure of interest and one of these was a very small pre-post study (n=3) incorporating a single-subject design with mixed results and no group results reported in response to a body-weight support treadmill training intervention (i.e., Effing et al. 2006). Of note, Klose et al. 1990 used an RCT design to examine the effect of four different combinations of conventional physical exercise therapy (PET i.e., strengthening, mat mobility, and transfer, self-care and wheelchair skills training), neuromuscular stimulation (NMS)-assisted exercise or EMG (EMG) biofeedback training focused on the upper limbs of males and females with tetraplegia (C4-C6) who were at least 1 year post-injury (n=43, 39 completing). Treatment subgroups received one of the following: 1) 8 weeks each of EMG biofeedback followed by PET; 2) 8 weeks each of EMG biofeedback followed by NMS; 3) 8 weeks each of NMS followed by PET; 4) 16 weeks of PET. All four of these treatment groups showed significant improvement on mobility and self-care scores (p<0.05) although there were no differences between groups with each method equally beneficial in terms of functional improvement.
In addition, da Silva et al. 2005 conducted a prospective controlled trial (n=16) examining the effect of a 4 month swimming program (45 minute 2x/week) on persons with complete SCI (14 with paraplegia) who had just been discharged from inpatient SCI rehabilitation. The primary outcome measure was the FIM and significant differences were noted for the FIM transfer subscale score (p=0.02), overall motor subscale score(p=0.01) and overall score (p=0.01) between those participating in the swimming program as compared to those in the control group who performed only their routine daily activities.
Duran et al. 2001 also incorporated the FIM in assessing the effects of a mixed exercise program involving three 120 minute sessions/week over 16 weeks. Participants were outpatients with paraplegia and 12 of 13 were ≥5 months post-injury (median 10 months). This structured program consisted of activities that were focused on mobility, aerobic resistance, strength, coordination, recreation and relaxation. Significant increases were seen in total FIM score relative to baseline (p<0.001) and time was reduced for all nine wheelchair skills tested (p<0.04 or less) associated with the exercise program. These benefits along with increases in strength and exercise capacity were seen in the absence of statistically significant changes in various physiological parameters (i.e., lipid profile, body composition) although each of these variables did approach significance (p=0.076 to 0.2).
Other investigations incorporated measures associated with the performance of ADLs or other functional measures as secondary objectives. Subjective self-reports of improved walking (with an aid), transferring, dressing and other tasks of daily living along with concomitant strength improvements associated with a FES cycling program were reported by Sloan et al. 1994 for all the incomplete study participants with chronic SCI (n=11 of 12). Hjeltnes and Wallberg-Henriksson 1998 demonstrated significant improvements in the Sunnaas ADL index and muscle strength in persons with tetraplegia in response to a 6-8 week program of 3 day/week 30 minute arm ergometry sessions. This latter investigation was conducted in persons with sub-acute SCI as part of inpatient rehabilitation. Without a suitable control condition, it was uncertain if these benefits were due to the arm ergometry intervention or other aspects of the rehabilitation program or were associated with natural recovery.
Subjective well-being (SWB) refers to how people evaluate their lives. It is a broadly-defined construct that encompasses an array of factors such as psychological well-being, satisfaction with health and physical functioning, and overall life satisfaction. Within the general population, considerable research has shown that regular participation in physical activity is associated with improvements in a wide range of SWB outcomes. In contrast, relatively little research has examined the effects of physical activity on aspects of SWB among people living with SCI.
Although a couple of Level 1 and 2 studies have been conducted, most research examining physical activity and SWB has been cross-sectional (e.g., Manns and Chad 1999; Muraki et al. 2000; Stevens et al. 2008; Tawashy et al. 2009) and is excluded from the present analysis. A wide range of SWB outcomes have been examined such as perceptions of community integration, pain, mood states, anxiety, perceived health, and self-efficacy. Some of these aspects--and their relationship with physical activity--are discussed in different chapters (e.g., community reintegration, pain). Other aspects (e.g., mood states, self-efficacy) have been examined in too few high quality studies to generate reliable conclusions, and have been excluded from the present analysis. Two aspects--depression and quality of life-- have been relatively well-studied in relationship to physical activity. As such, this section reviews only those studies that have included a measure of depression or quality of life.
Table: Physical Activity and Subjective Well-Being
With regards to depression, all but two studies (Hicks et al. 2005; Warms et al. 2004) showed positive effects of exercise on depressive symptoms (Guest et al. 1997; Hicks et al. 2003; Latimer et al. 2004; Latimer et al. 2005; Martin Ginis et al. 2003). In addition, Kennedy et al. 2006 showed significant reductions in anxiety but not depression using the Hospital Anxiety and Depression Scale with their 1 week physical activity course. Given the variety of modes of physical activity examined in these studies, the consistent findings speak to the robustness of the relationship between physical activity and depression among people living with SCI. In the studies that showed no significant effects of exercise on depression (Hicks et al. 2005; Kennedy et al. 2006; Warms et al. 2004), participants’ baseline depression scale scores were already extremely low, indicating minimal depressive symptomatology and very little room for improvement. As exercise has been shown to exert its greatest effects on people with greater depressive symptomatology, these findings are not particularly surprising.
With regards to quality of life, all of the Level 1, 2, and 4 studies showed that exercise training was associated with better quality of life (Ditor et al. 2003; Effing et al. 2006; Hicks et al. 2003; 2005; Kennedy et al. 2006; Latimer et al. 2004; Latimer et al. 2005; Martin Ginis et al. 2003; Semerjian et al. 2005). Again, given that this association held across different types of physical activity modalities and in studies that used different measures of quality of life, the physical activity-quality of life relationship appears to be robust. However, the one case-study (Effing et al. 2006) did not find quality of life improvements for two of its three participants. When contrasted with the findings of the higher quality studies, these null findings speak to the importance of examining changes in quality of life over time, and in sufficiently large and representative samples, in order to properly assess the effects of physical activity on SWB.
How does physical activity improve depression, quality of life, and potentially other aspects of SWB? This question was examined in a series of papers using data from Hicks et al. 2003’s RCT. Overall, these studies showed that exercise-induced reductions in stress and pain mediated the effects of exercise on quality of life and depression (Latimer et al. 2004; Martin Ginis et al. 2003). In other words, exercise training led to reductions in stress and pain, which, in turn, led to improvements in quality of life and depressive symptoms. There was also evidence that among people who were experiencing stressful life events, exercise helped to buffer the effects of the stress on their SWB (Latimer et al. 2005).
In general, several of the studies examining subjective well-being are constrained by an inadequate control group, making it difficult to discern whether it is the physical activity itself or some other aspect of a structured program that may be contributing to beneficial effects. Regardless, the conclusions below are based on the relative consistency across studies, despite these limitations. Of note, the trials conducted by Hicks et al. 2003 and Latimer et al. 2004 did provide an opportunity for education about exercise to their control group participants which afforded a more effective comparison than other trials which simply asked control group participants to maintain their usual activity patterns and defer initiation of an exercise program until after the study trial.
Numerous investigators and program planners have pointed to the occurrence of secondary complications or other health conditions that are encountered all too frequently by those with SCI as a means of providing rationale for their particular program of exercise or physical activity promotion (e.g., Rimmer 1999; Zemper et al. 2003; Block et al. 2005; Kosma et al. 2005). As noted previously, there is generally more support for an overall health benefit of physical activity in the able-bodied population including evidence for its role in the prevention of chronic disease (US Department of Health and Human Services 1996; Warburton et al. 2006; Kruk 2007). The present section is intended to outline the evidence that exists in SCI for specific interventions involving physical activity in preventing or mitigating the effects of various secondary health conditions. Specific secondary conditions addressed include those associated with maintaining or enhancing cardiovascular health and bone health as well as preventing or mitigating disability associated with respiratory complications, pain, spasticity and periodic leg movements.
The intent of this section is to bring the information about physical activity associated with various secondary health conditions into one place, as most of these secondary conditions comprise individual chapters with SCIRE. Therefore, we have selected to simply reference the existing chapters that contain information about physical activity interventions and to also bring forward the conclusions (i.e.,evidence statements and bottom-line conclusions) from these chapters so the reader will gain a sense of the degree of evidence across these various conditions. The reader is encouraged to examine the referenced chapter for surrounding discussion and more information concerning the various studies and details about the specific interventions comprising the evidence. Of note, many of the therapies associated with upper limb or lower limb management involve therapeutic exercise programming (often associated with physical or occupational therapy) and for these we simply refer the reader to SCIRE Chapters: Upper Limb Rehabilitation Following Spinal Cord Injury (Connolly et al. 2010) and Lower Limb Rehabilitation Following Spinal Cord Injury (Lam et al. 2010) respectively.
Cardiovascular disease, when considered after the first year post-injury within the US Model Systems database, has been acknowledged as the leading cause of death in persons with SCI, supplanting respiratory complications and previous to that septicaemia (Whiteneck et al. 1992; DeVivo et al. 1999). Cardiovascular disease is currently also the leading cause of death in the able-bodied population. A recent review by Myers et al. (2007) noted that there is a significantly high prevalence of cardiovascular disease in persons with SCI with rates of symptomatic cardiovascular disease in SCI of 30%–50% in comparison to 5%–10% in the general able-bodied population. Physical activity interventions comprise a significant part of the strategy in dealing with cardiovascular disease and the reader is referred to SCIRE Chapter: Cardiovascular Health and Exercise Following Spinal Cord Injury (Warburton et al. 2010) for more information on this topic. In the following section, we present those specific evidence-based statements and bottom-line conclusions from this chapter related to physical activity.
Treadmill training
Upper Extremity Exercise
Functional electrical stimulation (FES)– Lower Limb Cycle Ergometry and Hybrid (Upper and Lower Limb) and Other Electrically-Assisted Training Programs
Other than death due to external causes (e.g., motor vehicle accident, violence), respiratory complications, have consistently been among the two leading causes of death in persons with SCI when considered after the first year post-injury, and the highest cause of death within the first year post-injury, over the past 35 years within the US Model Systems database (DeVivo et al. 1999). As noted in SCIRE Chapter: Respiratory Management Following Spinal Cord Injury (Sheel et al. 2008):
“The lungs and airways do not change appreciably in response to exercise training. It is likely that exercise is not sufficiently stressful to warrant an adaptive response. This may be even more so when considering the small muscle mass used in wheelchair propulsion or arm cranking exercise. On the other hand, respiratory muscles are both metabolically and structurally plastic and they respond to exercise training. ... Exercise training may influence the control of breathing and respiratory sensations (i.e., dyspnea). It is generally accepted that exercise training results in a lower minute ventilation at any given absolute oxygen consumption or power output. This is likely due to a reduction in one or more of the mechanisms (neural and/or humoral) purported to cause the hyperpnea (increased respiratory rate) associated with exercise. As such, the positive effects of exercise training in SCI may reside in an increase in respiratory muscle strength and endurance as well as a reduced ventilatory demand during exercise.”
For more information about these and other interventions related to exercise and muscle activation related to respiratory complications, the reader is referred to SCIRE Chapter 8 - Respiratory Management Following Spinal Cord Injury (Sheel et al. 2008). In the following section, we present those specific evidence-based statements and bottom-line conclusions from this chapter related to physical activity.
Osteoporosis is a condition characterized by low bone mass and deterioration of the skeletal system and is often cited as a secondary complication associated with SCI (Giangregorio and McCartney 2006; Jiang et al. 2006). This bone deterioration results in skeletal fragility and leads to an increased risk of fractures. Physical activity interventions have been suggested as potential strategies for both prevention and treatment of loss of bone mineral density and the reader is referred to SCIRE Chapter: Bone Health Following Spinal Cord Injury (Ashe et al. 2010) for more information on this topic. In the following section, we present those specific evidence-based statements and bottom-line conclusions from this chapter related to physical activity.
There is level 4 evidence (from 1 pre-post study) (Chen et al. 2005) that 6 months of FES cycle ergometry increased regional lower extremity BMD over areas stimulated.
There is inconclusive evidence for Reciprocating Gait Orthosis, long leg braces, passive standing or self-reported physical activity as a treatment for low bone mass.
Pain is a frequently noted complication in persons with SCI. Although reports vary widely, given historical variation in pain classification and differences in rating pain severity across the various pain categories (i.e., at-, above- or below-lesion neuropathic pain; visceral; musculoskeletal) it is generally established that an average of about two-thirds of people with SCI report some form of pain and nearly one-third of these rate their pain as severe (Siddall and Loeser 2001). Physical activity interventions have been linked to mitigating some of the effects of chronic pain in SCI and the reader is referred to SCIRE Chapter: Pain Following Spinal Cord Injury (Teasell et al. 2010) for more information on this topic. In the following section, we present those specific evidence-based statements and bottom-line conclusions from this chapter related to physical activity.
There is level 1 evidence from a single RCT (Martin Ginis et al. 2003) that a regular exercise program significantly reduces post-SCI pain.
Regular exercise reduces post-SCI pain.
Spasticity, defined as “disordered sensori-motor control, resulting from an upper motor neurone lesion, presenting as intermittent or sustained involuntary activation of muscle” (Pandyan et al. 2005), is a frequent condition associated with SCI with as many as 78% of persons with chronic SCI reporting spasticity (Adams and Hicks 2005). Spasticity may not worsen with age or time, however uncontrolled spasticity has been suggested as having an impact on emotional adaptation, dependency, secondary health problems and environmental integration (Krause 2007). Physical activity interventions have demonstrated to reduce spasticity in SCI and the reader is referred to SCIRE: Spasticity Following Spinal Cord Injury (Hsieh et al. 2010) for more information on this topic. In the following section, we present those specific evidence-based statements and bottom-line conclusions from this chapter related to physical activity.
Restless legs syndrome and the associated phenomena of periodic limb movement have been noted to occur relatively frequently in persons with SCI (de Mello et al. 1996; Lee et al. 1996). In particular, periodic leg movements are characterized by rapid leg movements during sleep, especially ankle dorsiflexion combined with extension of the large toe and less frequently knee and/or hip flexion. These may occur for several minutes to several hours and may be associated with insomnia and daytime somnolence and the inherent effects this can have on one’s quality of life.
Table: Physical Activity and Periodic Limb Movements
Following 2 pilot studies showing positive effects with either a single session (de Mello et al. 1996) or multiple sessions (de Mello et al. 2002) of exercise training, de Mello and colleagues conducted a prospective controlled trial comparing the effect of 30 days of initial L-dopa or placebo treatment versus 45 days of three/week 30 minute aerobic arm ergometry exercise training sessions in reducing the incidence of periodic limb movements during sleep (de Mello et al. 2004). Participants were all male, with complete chronic paraplegia (AIS A, lesion levels between T7-T12) with participants crossing-over from 1 treatment to the next. The incidence of periodic limb movements was determined with polysomnographic analysis conducted as part of a sleep study and the effect of each treatment was noted relative to a baseline period. There was a 15 day washout period between the drug and exercise treatments to limit any carry-over effects. Both treatments were equally effective in reducing the amount of periodic limb movements such that the authors suggested a physical activity intervention as the first line of treatment and treatment with dopaminergic agonists to be reserved for persons who prove refractory to the exercise approach (De Mello et al. 2004).
It is generally accepted that physical activity is associated with numerous physical and psychological benefits for both the able-bodied and for persons with SCI. The previous section outlined numerous investigations providing evidence that various forms of physical activity and exercise programming are effective for a variety of SCI-related issues. However, more research is needed to determine the effect of specific parameters such as mode, duration, frequency and intensity to more fully delineate the specific characteristics that would guide exercise prescription for individuals with SCI. There are even fewer studies that are directed towards investigating interventions that are designed to increase participation in physical activity and also that provide the background information needed to effectively design these interventions. Even though it seems obvious and is generally assumed that participation in physical activity is severely limited in persons with SCI, the research base on existing levels of physical activity participation and the specific barriers that persons with SCI must overcome to participate is lacking.
It should be noted that determinations of participation levels and investigations of barriers to participation are not amenable to experimental investigation and typically do not involve an intervention, and therefore comprise subject areas which are typically not addressed according to SCIRE methodology. However, descriptions of the observational studies examining participation levels and barriers to participation are included here as an understanding of these factors is critical for rehabilitation care providers and health promoters to successfully develop and apply physical activity-promoting interventions directed toward persons with SCI. Finally, the effectiveness of interventions that promote physical activity participation of persons with SCI is assessed from the existing literature.
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.
Table: Physical Activity Participation in the SCI Population
Physical activity participation rates have been reported in three studies -- two 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 various activities preferred by individuals, most participants reporting LPTA did activities at a moderate level of intensity 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 Canadian study (Carpenter et al. 2007), 75% of respondents reported participating in “fitness activities” which included breathing and relaxation exercises (i.e., activities that do not necessarily require physical exertion or have fitness-enhancing benefits). 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 two studies (Latimer et al. 2006a; Tasiemski et al. 2005) in addition to the aforementioned information noted by Martin Ginis and colleagues (2010a, 2010b). Tasiemski et al. (2005) reported that the most commonly practiced 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 the 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.
The inactive lifestyle of individuals with SCI is a serious functional and health liability. Consequently, developing effective interventions to promote physical activity should be a research and public health priority (Rimmer 1999). In order to tailor interventions to the needs of individuals with SCI it is necessary to understand the factors affecting their participation in physical activity.
Among adult populations of persons with disabilities, frequently cited barriers impeding participation include: intrapersonal barriers (i.e., personal factors such as health concerns, motivation, and knowledge), systemic barriers (i.e., obstacles such as program costs and accessibility resulting from infrastructure and policy preventing participation or access), attitudinal barriers (i.e, stigma and negative stereotypes held by persons who are not impaired), and expertise barriers (i.e., gaps in practitioners’ knowledge and skill to effectively prescribe and supervise physical activity for adults with disability). The objective of this section is to examine the prominence of these barriers specifically in the SCI population. Indeed, barriers are a critical factor affecting participation in the SCI population (Latimer et al. 2004). For example, among a group of individuals with SCI exercising at an adapted exercise facility, participation rates were lowest among people experiencing more physical symptoms related to their injury (i.e., intrapersonal barriers; Ditor et al. 2003).
Table: Barriers to Physical Activity Participation in SCI
This series of four observational (level 5) studies provide an indication of frequently encountered barriers affecting physical activity participation in the SCI population (Martin et al. 2002; Scelza et al. 2005; Vissers et al. 2008; Kehn and Kroll 2009). Although all types of barriers as described above (i.e., intrapersonal, systemic, attitudinal, and expertise) were cited as obstacles to physical activity participation, intrapersonal, systemic, and expertise barriers were the most prominent and consistent. Further research should determine which of these barriers are most influential and modifiable. In turn, practitioners and researchers should direct their effort towards developing interventions to alleviate these key barriers.
Interestingly, two of the studies suggest that the physical activity barriers that people with SCI encounter vary depending on lesion level and time post injury. People with tetraplegia reported being more concerned about health conditions preventing exercise and exercise being too difficult than individuals with paraplegia (Scelza et al. 2005). Moreover, participants in the study by Vissers et al. (2008) indicated that they encountered more barriers to participation such as a need for more information and opportunity to participate in sport soon after discharge compared to later. Together these findings suggest that strategies for overcoming barriers to physical activity participation may be most effective when they are individualized to suit specific needs.
The evidence that a large segment of the SCI population does not engage in any leisure-time physical activity whatsoever emphasizes the need for effective interventions to help people with SCI to become more physically active. In the SCI population, the majority of physical activity intervention studies are efficacy trials establishing the effects of physical activity on specific health outcomes. Few studies have examined strategies for increasing physical activity participation in this population. Thus, it is not surprising that programs and information to increase physical activity are two of the services most desired but least available to people with SCI (Hart et al. 1996; Boyd and Bardak 2004). To begin addressing this gap, this section reviews the physical activity intervention studies that include a measure of physical activity participation as a study outcome.
In the general population, three types of physical activity interventions have strong evidence of effectiveness: (1) Informational interventions that focus on delivering information to change knowledge and attitudes about the benefits of and opportunities for physical activity (e.g., a community-based media campaign), (2) Behavioural interventions that focus on teaching behavioural skills to promote physical activity participation (e.g., goal-setting), and (3) Environmental and policy interventions that focus on changing the physical environment, social networks, organizational norms and policies to enable physical activity participation (Kahn et al., 2002). Our review of physical activity interventions in the SCI population focuses solely on behavioural interventions. This narrow scope is due to the complete lack of research testing the effectiveness of informational and environmental interventions in the SCI population.
Table: Interventions Promoting Physical Activity Participation in SCI
Although the sample sizes (n’s = 12-54) are small and the research methods are limited, the findings from the four published studies promoting physical activity for individuals with SCI are encouraging. Each of the level 1 and 2 studies (Arbour-Nicitopoulos et al. 2009; Latimer et al. 2006b; Zemper et al. 2003) reported a significant increase in physical activity participation following an intervention. The level 4 study (Warms et al. 2004) indicated a promising trend in which the majority of participants increased their participation over the course of the intervention.
In addition to providing evidence that physical activity participation in the SCI population is amenable to change, these studies begin to provide initial insight into essential intervention elements. All four studies used an established theoretical framework to guide the intervention content. Specifically, Zemper et al. (2003) developed their intervention based on self-efficacy theory (Bandura, 1986), Warms et al. (2004) applied the transtheoretical model (Prochaska et al. 1992), and Latimer et al. (2006b) and Arbour-Nicitopoulos et al. (2009) used the action phase model (Gollwitzer, 1993), with the latter study also incorporating coping planning methods (See Table 9 for descriptions of these models and underlying concepts). The application of these theories in intervention development ensured that important determinants of physical activity behaviour were being targeted thus, boosting the odds of behaviour change.
Table: Descriptions of Theoretical Frameworks and Underlying Concepts
From the studies by Latimer et al. (2006b) and Arbour-Nicitopoulos et al. (2009), we begin to gain an understanding of the impact of a specific intervention strategy on physical activity participation. Latimer et al. (2006b) demonstrated that assisting persons with the creation of implementation intentions is a simple and efficacious intervention technique. Arbour-Nicitopoulos et al. (2009) extended these observations by incorporating a coping planning strategy as part of systematic action planning to circumvent anticipated barriers with self-regulatory strategies. Because the studies by Zemper et al. (2003) and Warms et al. (2004) delivered multifaceted interventions including education, goal setting, and barrier management counselling, the isolated impact of each of these intervention strategies remains unknown.
There is level 4 evidence that the MAGIC wheels 2-gear wheelchair results in less shoulder pain.
There is level 1 evidence from a single study that passive ankle movements may not reduce lower limb muscle spasticity in persons with initial mild spasticity.
There is level 4 evidence from a single study that externally applied forces or passive muscle stretch as are applied in assisted standing programs may result in short-term reduction in spasticity. This is supported by individual case studies and anecdotal reports from survey-based research.