Impact of exercise training on oxidative stress in individuals with a spinal cord injury

Acute changes in antioxidants and oxidative stress to vigorous arm exercise: an intervention trial in persons with spinal cord injury and healthy controls

STUDY DESIGN

Intervention trial.

BACKGROUND

Literature remains unclear on possible health benefits and risks assosciated with high intensity exercise for persons with SCI. Elevated oxidative stress levels might influence their ability to exercise at high intensity. We investigated several biomarkers of oxidative stress and antioxidant defense at rest, during and after vigorous exercise among persons with chronic SCI.

SETTING

Sunnaas Rehabilitation Hospital, Norway.

METHODS

Six participants (five males) with chronic SCI (AIS A, injury level thoracic 2-8, >1 year postinjury) and six matched able-bodied controls performed two maximal arm-cranking tests, with one-three days in between. During the second exercise test, participants performed three bouts with four minutes arm cranking at high intensity (85-95% of peak heart rate (HR_peak)), before they reached maximal effort. Blood and urine biomarkers for oxidative stress and antioxidant levels were collected at six time points at the day of the second exercise test; baseline, at high intensity exercise, at maximal effort, at five, 30 and 60 min post-exercise, and 24 h post exercise.

RESULTS

Participants with SCI had significant lower levels of creatinine (∆16 µmol/L, p = 0.03), α-carotene (∆0.14 nmol/L, p < 0.001) and β-carotene (∆0.51 nmol/L, p = 0.001) at baseline compared to controls. Urine and blood biomarkers of oxidative stress and antioxidant levels showed similar response to vigorous exercise in the SCI and control group.

CONCLUSIONS

SCI participants showed similar changes in redox status during high intensity exercise compared to matched able-bodied. SCI participants had lower levels of exogen antioxidants both before, during and after vigorous exercise.

The Influence of Exercise on Oxidative Stress after Spinal Cord Injury: A Narrative Review

Spinal cord injury (SCI) is an irreversible disease resulting in partial or total loss of sensory and motor function. The pathophysiology of SCI is characterized by an initial primary injury phase followed by a secondary phase in which reactive oxygen species (ROSs) and associated oxidative stress play hallmark roles. Physical exercise is an indispensable means of promoting psychophysical well-being and improving quality of life. It positively influences the neuromuscular, cardiovascular, respiratory, and immune systems. Moreover, exercise may provide a mechanism to regulate the variation and equilibrium between pro-oxidants and antioxidants. After a brief overview of spinal cord anatomy and the different types of spinal cord injury, the purpose of this review is to investigate the evidence regarding the effect of exercise on oxidative stress among individuals with SCI.

Systemic and Pulmonary Inflammation/Oxidative Damage: Implications of General and Respiratory Muscle Training in Chronic Spinal-Cord-Injured Patients

Chronic spinal cord injury affects several respiratory-function-related parameters, such as a decrease in respiratory volumes associated with weakness and a tendency to fibrosis of the perithoracic muscles, a predominance of vagal over sympathetic action inducing airway obstructions, and a difficulty in mobilizing secretions. Altogether, these changes result in both restrictive and obstructive patterns. Moreover, low pulmonary ventilation and reduced cardiovascular system functionality (low venous return and right stroke volume) will hinder adequate alveolar recruitment and low O₂ diffusion, leading to a drop in peak physical performance. In addition to the functional effects described above, systemic and localized effects on this organ chronically increase oxidative damage and tissue inflammation. This narrative review describes both the deleterious effects of chronic spinal cord injury on the functional effects of the respiratory system as well as the role of oxidative damage/inflammation in this clinical context. In addition, the evidence for the effect of general and respiratory muscular training on the skeletal muscle as a possible preventive and treatment strategy for both functional effects and underlying tissue mechanisms is summarized.

Functional electrical stimulation cycling exercise after spinal cord injury: a systematic review of health and fitness-related outcomes

OBJECTIVES

The objective of this review was to summarize and appraise evidence on functional electrical stimulation (FES) cycling exercise after spinal cord injury (SCI), in order to inform the development of evidence-based clinical practice guidelines.

METHODS

PubMed, the Cochrane Central Register of Controlled Trials, EMBASE, SPORTDiscus, and CINAHL were searched up to April 2021 to identify FES cycling exercise intervention studies including adults with SCI. In order to capture the widest array of evidence available, any outcome measure employed in such studies was considered eligible. Two independent reviewers conducted study eligibility screening, data extraction, and quality appraisal using Cochranes' Risk of Bias or Downs and Black tools. Each study was designated as a Level 1, 2, 3 or 4 study, dependent on study design and quality appraisal scores. The certainty of the evidence for each outcome was assessed using GRADE ratings ('High', 'Moderate', 'Low', or 'Very low').

RESULTS

Ninety-two studies met the eligibility criteria, comprising 999 adults with SCI representing all age, sex, time since injury, lesion level and lesion completeness strata. For muscle health (e.g., muscle mass, fiber type composition), significant improvements were found in 3 out of 4 Level 1-2 studies, and 27 out of 32 Level 3-4 studies (GRADE rating: 'High'). Although lacking Level 1-2 studies, significant improvements were also found in nearly all of 35 Level 3-4 studies on power output and aerobic fitness (e.g., peak power and oxygen uptake during an FES cycling test) (GRADE ratings: 'Low').

CONCLUSION

Current evidence indicates that FES cycling exercise improves lower-body muscle health of adults with SCI, and may increase power output and aerobic fitness. The evidence summarized and appraised in this review can inform the development of the first international, evidence-based clinical practice guidelines for the use of FES cycling exercise in clinical and community settings of adults with SCI. Registration review protocol: CRD42018108940 (PROSPERO).

Denervation does not Induce Muscle Atrophy Through Oxidative Stress

Denervation leads to the activation of the catabolic pathways, such as the ubiquitin-proteasome and autophagy, resulting in skeletal muscle atrophy and weakness. Furthermore, denervation induces oxidative stress in skeletal muscle, which is thought to contribute to the induction of skeletal muscle atrophy. Several muscle diseases are characterized by denervation, but the molecular pathways contributing to muscle atrophy have been only partially described. Our study delineates the kinetics of activation of oxidative stress response in skeletal muscle following denervation. Despite the denervation-dependent induction of oxidative stress in skeletal muscle, treatments with anti-oxidant drugs do not prevent the reduction of muscle mass. Our results indicate that, although oxidative stress may contribute to the activation of the response to denervation, it is not responsible by itself of oxidative damage or neurogenic muscle atrophy.

A Wellness Program for Men With Spinal Cord Injury: Participation and Meaning

Little is known about how participating in a wellness program influences the well-being of individuals with spinal cord injury (SCI). The purpose of this study is to explore how men with SCI describe their experiences and meaning of participating in a wellness center program, how they perceived these experiences as influencing their well-being, and how these experiences relate to co-occupations and occupational spin-off concepts. Investigators employed a descriptive qualitative design. Four adult males with an SCI participated in the study. Data collection methods included individual semi-structured interviews and observations. Participation in a wellness program positively influenced the physical, mental, and social well-being of participants. Findings expand our understanding of the value of social environment, social participation, co-occupations, and occupational spin-off. It is essential that occupational therapists promote occupational justice by advocating for clients so they can participate in wellness occupations in the community.

Allicin protects spinal cord neurons from glutamate-induced oxidative stress through regulating the heat shock protein 70/inducible nitric oxide synthase pathway

Allicin, the main biologically active compound derived from garlic, exerts a broad spectrum of pharmacological activities and is considered to have therapeutic potential in many neurological disorders. Using an in vitro spinal cord injury model induced by glutamate treatment, we sought to investigate the neuroprotective effects of allicin in primary cultured spinal cord neurons. We found that allicin treatment significantly attenuated glutamate-induced lactate dehydrogenase (LDH) release, loss of cell viability and apoptotic neuronal death. This protection was associated with reduced oxidative stress, as evidenced by decreased reactive oxygen species (ROS) generation, reduced lipid peroxidation and preservation of antioxidant enzyme activities. The results of western blot analysis showed that allicin decreased the expression of inducible nitric oxide synthase (iNOS), but had no effects on the expression of neuronal NOS (nNOS) following glutamate exposure. Moreover, allicin treatment significantly increased the expression of heat shock protein 70 (HSP70) at both mRNA and protein levels. Knockdown of HSP70 by specific targeted small interfere RNA (siRNA) not only mitigated allicin-induced protective activity, but also partially nullified its effects on the regulation of iNOS. Collectively, these data demonstrate that allicin treatment may be an effective therapeutic strategy for spinal cord injury, and that the potential underlying mechanism involves HSP70/iNOS pathway-mediated inhibition of oxidative stress.

Potential role of oxidative stress on the prescription of rehabilitation interventions in spinal cord injury

STUDY DESIGN

Review article.

OBJECTIVES

To provide an overview of free radical biology, particularly with respect to muscle physiology, as well as the potential effects of muscle morphological changes, physical capacity and nutritional status on oxidative stress in people with chronic spinal cord injury (SCI). The potential implications of these factors for determining the optimal dosage of rehabilitation training interventions in people with chronic SCI will also be presented.

SETTING

Vancouver, BC, Canada.

METHODS

Literature review.

RESULTS

Not applicable.

CONCLUSION

There has been a great deal of focus on rehabilitation exercise interventions providing intensive practice of movements to enhance functional recovery and physical capacity following SCI. However, there is still much to be understood about the appropriate dosage of training parameters (e.g. frequency, duration). It has been known for several decades that exercise increases free radical production, leading to oxidative stress. To date, there has been little consideration of the potential interaction of oxidative stress with training parameters on functional outcomes in chronic SCI. Furthermore, individuals with chronic SCI face many secondary consequences of their injury, such as muscle atrophy, change in muscle fiber type, general deconditioning and nutritional status, that are known to influence free radical production and antioxidant capacity. Better understanding of the potential confounding effects of oxidative stress associated with exercise will improve our ability to determine the optimal 'dose' of rehabilitation training to maximize functional recovery following SCI.

Arm-cranking exercise reduced oxidative damage in adults with chronic spinal cord injury

OBJECTIVE

To assess the effect of a 12-week arm-cranking exercise program on reducing oxidative damage in untrained adults with chronic spinal cord injury (SCI).

DESIGN

Randomized controlled trial.

SETTING

Community-based supervised intervention.

PARTICIPANTS

Male adults with complete SCI at or below the fifth thoracic level (T5) (N=17) volunteered for this study. Participants were randomly allocated to the intervention (n=9) or control (n=8) group using a concealed method.

INTERVENTION

A 12-week arm-cranking exercise program, 3 sessions/wk, consisting of warming-up (10-15min) followed by a main part in arm-crank (20-30min [increasing 2min and 30s every 3wk]) at a moderate work intensity of 50% to 65% of the heart rate reserve (starting at 50% and increasing 5% every 3 weeks) and by a cooling-down period (5-10min).

MAIN OUTCOME MEASURES

Plasmatic levels of total antioxidant status as well as erythrocyte glutathione peroxidase activity were measured. Lipid and protein oxidation were determined as malondialdehyde and carbonyl group levels, respectively. Furthermore, physical fitness and body composition were assessed.

RESULTS

When compared with baseline results, maximum oxygen consumption was significantly increased (P=.031), suggesting an improvement in physical fitness in the intervention group. Regarding the antioxidant defense system, it was found that both total antioxidant status (P=.014) and erythrocyte glutathione peroxidase activity (P=.027) were significantly increased at the end of the training program. As a consequence, plasmatic levels of malondialdehyde (P=.008) and carbonyl groups (P=.022) were significantly reduced.

CONCLUSION

A 12-week arm-cranking exercise program improved the antioxidant defense system in adults with chronic SCI, which may finally attenuate both lipid and protein oxidation in this population.

Time-course response in serum markers of bone turnover to a single-bout of electrical stimulation in patients with recent spinal cord injury

The objective of the present repeat-measures study was to determine whether plasma serum levels of testosterone, cortisol, osteocalcin or type I collagen C-telopeptide (CT) are acutely affected following an electro-myostimulation (EMS) bout, and their relation to bone mineral density and muscle mass. Ten men with recent (8 weeks) thoracic spinal cord injury (SCI) (ASIA A) and 10 age-matched able-bodied (AB) men performed one EMS bout on the quadriceps femoris muscle. Blood samples were drawn at basal condition, immediately after EMS, and 15 min, 30 min, 24 h and 48 h post-EMS. Muscle cross-sectional area was measured by magnetic resonance imaging. Bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry. In the SCI group, a significant decrease in testosterone, cortisol and CT together with a significant increase in testosterone/cortisol ratio and osteocalcin/CT ratio was observed after EMS. For the AB subjects, only testosterone and CT decreased significantly following EMS. Muscle size was only related to testosterone/cortisol ratio in the SCI sample (R = 0.659, p < 0.05), whereas BMD did not show any relation to any biomarker. Acute EMS in recent spinal cord injured men seems to induce positive effects on bone turnover biomarkers, and anabolic and catabolic hormones.

Blood vessel remodeling and physical inactivity in humans

Physical inactivity is associated with an increase in cardiovascular risk that cannot be fully explained by traditional or novel risk factors. Inactivity is also associated with changes in hemodynamic stimuli, which exert direct effects on the vasculature leading to remodeling and a proatherogenic phenotype. In this review, we synthesize and summarize in vivo evidence relating to the impact of local and systemic models of physical inactivity on conduit arteries, resistance vessels, and the microcirculation in humans. Taken together, the literature suggests that a rapid inward structural remodeling of vessels occurs in response to physical inactivity. The magnitude of this response is dependent on the "dose" of inactivity. Moreover, changes in vascular function are found at resistance and microvessel levels in humans. In conduit arteries, a strong interaction between vascular function and structure is present, which results in conflicting data regarding the impact of inactivity on conduit artery function. While much of the cardioprotective effect of exercise is related to the nitric oxide pathway, deconditioning may primarily be associated with activation of vasoconstrictor pathways. The effects of deconditioning on the vasculature are therefore not simply the opposite of those in response to exercise training. Given the importance of sedentary behavior, future studies should provide further insight into the impact of inactivity on the vasculature and other (novel) markers of vascular health. Moreover, studies should examine the role of (hemodynamic) stimuli that underlie the characteristic vascular adaptations during deconditioning. Our review concludes with some suggestions for future research directions.