Table 1.
Characteristics of clinical trials included in current systematic review
| Lead author, publication date and country | Sample size (N) and percentage of male population | Duration (weeks) | Intervention characteristics | SCI duration (years) | SCI injury type | Mean age (years) | Mean BMI (kg/m2) | Health status | Overall risk of bias | The main findings | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Intervention | Control | ||||||||||
| Akkurt et al., 20171 [73]; Turkey | 33 (29, 88%) | 12 | General rehabilitation exercises and aerobic exercise with the arm ergometer for 2 sessions/day 5 days/week | Only general rehabilitation exercises for 2 sessions/day 5 days/week | 3.43 ± 3.14 | Traumatic, motor complete and incomplete cervical, thoracic and lumbar SCI | 34.7 ± 10.3 | 23.7 ± 3.8 | Otherwise healthy (i.e., pressure sores, Bladder infections, cardiovascular diseases or contraindication for exercise) | High | There were no statistically significant intergroup differences at Weeks 0–6, Weeks 6–12 and Weeks 0–12, both in the intervention group and the control group with regard to metabolic syndrome parameters (TC, TG, HDL, LDL, glucose, waist circumference, SBP, DBP) |
| Gorgey et al., 20162 [74]; USA | 11 (11, 100%) | 16 | Two exercise interventions (functional electrical stimulation cycling versus arm cycling ergometer), 5 days/week | Two overnight stays/pre-training and were used to control for the effects of aging with SCI | 5.5 ± 4 | Chronic motor complete SCI (C6–T10; AIS A or B). No information on the type of trauma | 38 ± 9 | 25.7 ± 4.3 | Comorbidities were not reported/discussed) | Some concerns | There were no changes in the lipid profile in either the exercise or the control groups following the post-intervention or in the follow-up assessment visits |
| Hicks et al., 2003 [75]; Canada | 34 (NA) | 36 | Supervised progressive 90–120 min exercise training twice weekly for 9 months. Subjects began each exercise session with a warm-up (wheeling around the indoor track or low-intensity arm ergometry) and gentle upper extremity stretching followed an aerobic training, which involved arm ergometry for 15–30 min, at an intensity of approximately 70% maximum heart rate | Control group was offered a bi-monthly education session (together with the EX group) on topics including exercise physiology for persons with SCI, osteoporosis after SCI, and relaxation techniques | 9.4 ± 5.9 | Traumatic, motor complete and incomplete cervical to lumbar SCI) | 39.3 ± 10.7 | NA | Otherwise healthy subjects Individuals with ischemic heart disease, unstable angina, dysrhythmia, or autonomic dysreflexia, recent osteoporotic fracture, and tracheostomy were excluded) | High | There were no differences between groups in resting measures of heart rate, SBP or DBP at baseline, nor were there any changes in these variables in either group over the 9 months. Subjects with tetraplegia had similar resting HRs as those with paraplegia, but significantly lower SBP and DBP pressures; there was no effect of time or group assignment on these measures |
| Kim et al., 2015 [68]; South Korea | 15 (9, 60%) | 6 | The 60 min of exercise/day, 3 days a week for 6 weeks under the supervision of an exercise trainer consisting of 8 min warm up, 44 min on of hand bike exercise and 8 min cool down | Usual activities | 6.5 ± 3.8 | Motor complete and incomplete cervical and thoracic SCI. No information on the type of trauma | 33.1 ± 5.4 | 21.4 ± 3.2 | Otherwise healthy SCI individuals (e.g., cardiovascular disease, uncontrolled type 2 diabetes and hypertension excluded) | High | Participation in a six-week exercise program significantly decreased BMI (baseline: 22.0 ± 3.7 m/kg2 vs. post-intervention: 21.7 ± 3.5 m/kg2), fasting insulin (baseline: 5.4 ± 2.9 µU/ml vs. post-intervention: 3.4 ± 1.5 µU/ml), and HOMA-IR (baseline: 1.0 ± 0.6 vs. post-intervention: 0.6 ± 0.3) levels compared to the control group. HDL-C level (baseline: 42.4 ± 11.5 mg/dl vs. post-intervention: 46.1 ± 12.3 mg/dl) increased significantly after training. No significant changes in glucose, TC, TG, or LDL-C levels were observed in the exercise group. VO2 peak (baseline: 16.8 ± 7.2 ml/kg/min vs. post-intervention: 21.2 ± 9.1 ml/kg/min) increased significantly in the exercise group compared to the control group (mean difference vs. control, − 2.9 ml/kg/min) |
| Kim et al., 2019 [69]; South Korea | 17 (12, 65%) | 6 | Daily exercise program consisted of a 25-min warm-up consisting of 5 min of joint exercises, 15 min of exercise on an arm ergometer, and 5 min of stretching, followed by a 30-min exercise program (resistance, circuit, and aerobic training), and a 5 min of cool down (stretching), but the contents of the 30-min exercise were customized for each individual depending on the comorbidities and other factors | Standard care without exercise | 10.53 ± 6.9 | Motor complete and incomplete cervical, thoracic, and lumbar SCI. No information on the type of trauma | 36.8 ± 6.9 | 21.9 ± 2.82 | Otherwise healthy SCI individuals. Individuals with CVD, uncontrolled type 2 diabetes and hypertension, pressure ulcers, and orthopedic problems were excluded | High | The 6-week exercise program significantly decreased the average fasting insulin (baseline: 7.5 ± 4.7 µU/ml vs. post intervention: 4.5 ± 2.2 µU/ml, p < 0.05) and HOMA-IR (baseline: 1.5 ± 1.0 vs. post-intervention: 0.9 ± 0.4, p < 0.05) in the exercise group, whereas there was no change in control group (between group difference, mean fasting insulin: − 3.2 µU/ml, p = 0.003; mean HOMA-IR: − 0.66, p = 0.001). HDL-C has increased in exercise group and decreased in control group during the follow up (pre-post difference was 5.5 mg/dl ± 8.0 in exercise group and − 1.7 mg/dl ± 1.9 in control group, p = 0.021). There were no differences in glucose, TC and LDL |
| Lavado et al., 2013 [76]; Brazil | 42 (35, 83.3%) | 16 | Aerobic physical conditioning with moderate intensity of for one hour, twice or three times a week | Control group maintained their daily life activities | 4.4 ± 1.9 | Cervical and thoracic, motor complete and incomplete | 36.3 ± 7.6 | NA | Comorbidities were not reported/discussed | Some concerns | The increase of oxygen consumption in the intervention group compared to the control group was observed only at the end of the program. In the values before and after the training period of the intervention group significant differences were also observed |
| Nightingale et al., 2017 [21] and 2018 [77]; UK | 21 (15, 71%) | 6 | Home-based moderate intensity exercise using a portable arm-crank ergometer four times a week. The first exercise session was supervised by an experimenter and extended by 5 min per session throughout the first week (i.e. from 30–45 min). The last stretch of exercise was > 36 h before follow-up laboratory testing | The control group were encouraged to maintain their usual lifestyle | 16.29 ± 10.9 | Motor incomplete thoracic SCI. No information on the type of trauma | 46.8 ± 7.7 | NA | Individuals without acute health issues (i.e., pressure sores, urinary tract infections, and cardiovascular contraindications for testing) or musculoskeletal complaints, and not taking antihyperglycemic medication | High | Compared with controls, intervention group significantly decreased serum fasting insulin (Δ, 3.1 ± 10.7 pmol/l for control and − 12.7 ± 18.7 pmol/l for intervention) and homeostasis model assessment of insulin resistance (HOMA2-IR; Δ, 0.06 ± 0.20 for control and − 0.23 ± 0.36 for intervention). Adipose tissue metabolism, composite insulin sensitivity index (C-ISI Matsuda), and other cardiovascular disease risk biomarkers were not different between groups. The exercise group also increased the VO2 peak (Δ, 3.4 ml/kg min) |
| Ordonez et al., 2013 [55]3; Spain | 17 (17, 100%) | 12 | The 3 sessions/week, consisting of warming-up [10–15 min] followed by arm-crank (20–30 min [increasing 2 min and 30 s every 3 weeks]) at moderate work intensity of 50–65% of the heart rate reserve (Starting at 50% and increasing 5% every 3 weeks) and by a cooling down period [5–10 min] | Individuals matched on age, sex, and injury level who did not take part in any training program | 4.6 ± 0.29 | Traumatic, motor complete SCI below the fifth thoracic level (T5) | 29.9 ± 2.6 | 27.7 ± 4.0 | Healthy (individuals with smoking habits and alcohol consumers and individuals receiving medication and/or antioxidantconsumption that may interfere with the redox homeostasis were excluded) | Low | Both total antioxidant status (0.64 ± 0.2 mmol/l vs. 0.88 ± 0.1 mmol/l) and erythrocyte GPX activity (23.6 ± 2.4U/g hemoglobin vs. 27.8 ± 2.2U/g hemoglobin) were significantly increased at the end of the training program. Lipid peroxidation, expressed as plasmatic levels of malondialdehyde, was significantly reduced (0.48 ± 0.13 mmol/l vs. 0.35 ± 0.11 mmol/l). Similarly, protein oxidation, expressed as plasmatic carbonyl group level, was decreased after exercise (1.92 ± 0.3 nmol/mg protein vs. 1.33 ± 0.2 nmol/mg). In the control group, no significant changes in any of the tested parameters were found |
| Pelletier et al., 20154 [78]; Canada | 23 (21,91.3%) | 16 | Training involved ≥ 20 min of moderate-vigorous aerobic exercise (rating of perceived exertion 3e6 on 10-point scale) and 3–10 repetitions of upper-body strengthening exercises (50%-70% 1 repetition maximum) 2 times per week | Control group maintained existing physical activity levels with no guidance on training intensity | 12.0 ± 10.0 | Cervical, thoracic, motor complete and incomplete | 40.4 ± 11.6 | NA | Comorbidities were not reported/discussed | Some concerns | There was a significant increase in peak aerobic capacity (relative VO2 peak: 17.2%, absolute VO2 peak: 9.9%) and submaximal power output (26.3%) in the control group only |
| Rosety-Rodriguez et al., 2014 [56]; Spain | 17 (17, 100%) | 12 | Arm cranking exercise program of 3 sessions/week consisting of warm-up (10–15 min), arm crank (20–30 min; increasing 2 min and 30 s every 3 weeks) at a moderate work intensity of 50–65% of heart rate reserve (starting at 50% and increasing 5% every 3 weeks), plus cool-down (5–10 min) | The control participants completed baseline assessments but did not take part in the training program | 4.6 ± 0.29 | Traumatic, complete SCI at or below T5 | 29.9 ± 3.7 | 27.7 ± 4.2 | Otherwise healthy (individuals with pressure ulcers and/or coexisting infections, smoking/alcohol intake and receiving medication that may interfere with metabolism, participation in a training program in the 6 months prior to participation in the trial were excluded) | Low | When compared with baseline, plasma levels of leptin, TNF-a, and IL-6 were significantly decreased in the intervention group. In contrast, no significant changes were found in plasma concentrations of adiponectin and plasminogen activator inhibitor-1 (PAI-1) |
| Totosy de Zepetnek et al. [54]; Canada | 23 (21, 91%) | 16 | The training involved ≥ 20 min of moderate-vigorous aerobic exercise (rating of perceived exertion 3e6 on 10-point scale) and 3–10 repetitions of upper-body strengthening exercises (50%-70% 1 repetition maximum) 2 times per week | Control group maintained existing physical activity levels with no guidance on training intensity | 12.0 ± 9.9 | Motor complete and incomplete cervical and thoracic SCI. No information on the type of trauma | 41.4 ± 11.6 | 26.5 ± 5.1 | Individuals with any progressive loss of neurologic function within the previous 6 months were excluded | High | When implemented as part of a supervised training program, the physical activity guidelines for adults with SCI has a positive influence on some aspects of body composition and carotid vascular health. Despite these benefits, 16 weeks of adherence to the physical activity guidelines did not elicit changes in other CVD risk factors. There was a significant increase in peak aerobic capacity |
BMI: body mass index; CVD: cardiovascular disease; DBP: diastolic blood pressure; HDL: High density lipoprotein; HOMA-IR: Homeostatic model assessment for insulin resistance; IL-6: interleukin 6; LDL: Low density lipoprotein; SBP: systolic blood pressure; TC: total cholesterol; TNF-a: tumor necrosis factor alpha
Among 11 RCTs, 7 contributed to meta-analyses, reasons for exclusion are provided below:
1Control group received a general rehabilitation exercises, and the population included individuals in subacute injury phase, thus it was not included in meta-analysis (all other trials included subjects in chronic phase of the injury)
2Used two types of exercise and did not disaggregate data for functional electrical stimulation (FES), thus it was not included in meta-analysis (FES was exclusion criteria)
3Overlapping population with Rosety-Rodriguez et al., 2014, none of trial included in meta-analysis as there were no additional trials to report on inflammation/oxidative stress parameters
4Partially overlapping population with study by Totosy de Zepetnek et al. [54]