Exercise and Strengthening
Exercise as a rehabilitative therapy in SCI involves the use of repetitive and effortful muscle contractions to increase motor unit activity (Sandrow-Feinberg et al. 2009; Ada et al. 2006). Exercise may be classified as strength training or functional strength training. Strength training involves isolation and stabilization of muscles through training protocols involving free weights or machines (Tomlijenovic et al. 2011), while functional strength training utilizes training programs centered around activities of daily living (Tomlijenovic et al. 2011). These exercises often involve multiple muscle groups and require functional movements that are more applicable to daily life, thereby improving strength for performing everyday tasks (Tomlijenovic et al. 2011).
Engaging in repetitive physical therapy that is active or passive has many beneficial effects for individuals with SCI including preserved muscle mass (Houle et al. 1999), restored motor and sensory function (Hutchinson et al. 2004. Sandrow-Feinberg et al. 2009), induced synaptic plasticity by way of neurotrophic factor production (Vaynman et al. 2003), increased concentration of neurotrophic factors in spinal and muscle tissue (Gomez-Pinilla et al. 2002; Ying et al. 2005; Cote et al. 2011) and reduced inflammation around the lesion site (Sandrow-Feinberg et al. 2009). However, SCI often limits an individual’s ability to partake in exercise (Crane et al. 2015). This is a contributing factor to the incidence of obesity, cardiovascular disease and diabetes is two to four times higher in individuals with SCI compared to the general population (Evans et al. 2015).
Few evidence-based analyses on the efficacy of specific exercise therapies on upper extremity function exist (Ginis et al. 2008). The majority of research has focused on individual components of physical capacity (e.g. peak oxygen uptake, muscle strength, or respiratory function), rather than functional outcomes. Additional studies regarding cardiovascular and exercise interventions are discussed in the Cardiovascular chapter and Physical Activity chapter.
The methodological details and results from seven studies evaluating exercise and strengthening for upper extremity function are presented in Table 1.
Discussion
All seven studies presented found that exercise and strengthening were effective in improving upper extremity function. To date, these are the only studies that have tested exercise and strengthening for upper extremity rehabilitation in SCI. Interestingly, across all studies a wide variety of different types of exercise were efficacious. Trumbower and colleagues (2017) found that acute intermittent hypoxia, when combined with hand opening exercise improved hand function in individuals with SCI. Nightingale et al. (2018) investigated the efficacy of a home-based exercise program and found it improved health-related quality of life. Hicks et al. (2003), Haisma et al. (2006), and Drolet et al. (1999) studied traditional in-patient exercise rehabilitation programs and found significant improvements in upper extremity function. Study participants also reported decreases in stress, pain, depression, enhanced physical self-concept, and overall quality of life. Similarly, Hoffman et al. (2017) demonstrated significant improvements in hand function with the completion of a more traditional activity-based rehabilitation therapy. Gant et al. (2018) found significant improvements in upper extremity muscle strength with a multi-modal exercise training program. In this training program, a combination of activities was performed including body-weight-treadmill training, circuit resistance training for upper body conditioning, functional electrical stimulation, and wheelchair skills training.
In summary, regardless of the training modality used, individuals experienced increases in muscle strength, hand function, and quality of life. However, further research is necessary to directly compare the efficacy of each exercise/strength training program to each other. In addition, Haisma et al. (2006) and Sipski and Richards (2006) recommended further research in a variety of areas including optimal methods for strengthening muscles, merits of endurance versus strength training, and ROM, ADL, and transfer training. the impact of body composition, age, and concomitant medical problems on exercise efficacy should also be explored. Furthermore, longitudinal studies are needed to gain more insight into the changes that occur after inpatient rehabilitation and the factors which influence these changes.
Conclusion
There is level 1b evidence (from one randomized controlled trial: Trumbower et al. 2017) that acute intermittent hypoxia combined with daily hand opening practice significantly improves hand opening in some, but not all, aspects of hand function.
There is level 1b evidence (from one randomized controlled trial: Nightingale et al. 2018) that six weeks of home-based upper-body exercise improves aspects of health-related quality of life.
There is level 2 evidence (from one randomized controlled trial: Hicks et al. 2003) that physical capacity continues to improve 1- year post-discharge and is correlated to a decrease in stress, pain, and depression.
There is level 2 evidence (from one prospective controlled trial: Haisma et al. 2006) that physical capacity (strength and respiratory function) improves during and after inpatient rehabilitation.
There is level 4 evidence (from one pre-post study: Gant et al. 2018) that multi-modal exercise improves muscle strength and function in individuals with SCI.
There is level 4 evidence (from one pre-post study: Hoffman et al. 2017) that weekly activity-based hand therapy is feasible and efficacious at increasing hand task performance in individuals with SCI.
There is level 4 evidence (from one pre-post study: Drolet et al. 1999) that overall muscle strength continues to improve up to 15 months post-hospital discharge for both persons with tetraplegia and paraplegia despite large variability in patients.
