Reference fitness values in the untrained spinal cord injury population

Exercise and Health-Related Risks of Physical Deconditioning After Spinal Cord Injury

A sedentary lifestyle occurring soon after spinal cord injury (SCI) may be in contrast to a preinjury history of active physical engagement and is thereafter associated with profound physical deconditioning sustained throughout the lifespan. This physical deconditioning contributes in varying degrees to lifelong medical complications, including accelerated cardiovascular disease, insulin resistance, osteopenia, and visceral obesity. Unlike persons without disability for whom exercise is readily available and easily accomplished, exercise options for persons with SCI are more limited. Depending on the level of injury, the metabolic responses to acute exercise may also be less robust than those accompanying exercise in persons without disability, the training benefits more difficult to achieve, and the risks of ill-considered exercise both greater and potentially irreversible. For exercise to ultimately promote benefit and not impose additional impairment, an understanding of exercise opportunities and risks if exercise is undertaken by those with SCI is important. The following monograph will thus address common medical challenges experienced by persons with SCI and typical modes and benefits of voluntary exercise conditioning.

Predictive factors of peak aerobic capacity using simple measurements of anthropometry and musculoskeletal fitness in paraplegic men

BACKGROUND

Protocols for evaluating cardiovascular fitness for wheelchair-dependent persons are still scarcely accessible due to the requirements such as specialized equipment and expertise in community or public healthcare settings. This study aimed to assess the potential of secondary utilization of musculoskeletal fitness components for estimating peak oxygen uptake (VO2peak) in paraplegic men.

METHODS

Thirty-three paraplegic men (T1-L3) aged 23-63 years underwent anthropometry (height, weight and calculated body mass index and body surface area) and upper-body musculoskeletal fitness tests (back-scratch, arm-curls and handgrip strength tests) and performed a graded exercise test with an arm-crank ergometer on two non-consecutive days. To determine the relationship between VO2peak and various kinanthropometric parameters and derive a regression model that predicts the VO2peak, uni- and multivariate analyses were conducted, respectively.

RESULTS

Maximal numbers of arm curls on either arm (r=0.486, P=0.004) and the back-scratch distance (r=0.426, P=0.013) were moderately correlated with VO2peak. Moreover, among the indices of handgrip strength, average handgrip strength of both hands divided by the body surface area showed a strong correlation coefficient with VO2peak (r=0.674, P<0.001). Multivariate linear regression analysis indicated that muscular endurance and strength were the main predictors for estimating VO2peak. Considering shoulder flexibility, age, and anthropometric variables, the regression model showed the highest adjusted R2 of 0.811 and lowest standard error of estimate of 3.54 mL·kg-1·min-1 (P<0.001). The Bland-Altman plots indicated good agreement between actual and estimated VO2peak. The mean absolute prediction error was 11.9%.

CONCLUSIONS

Musculoskeletal fitness and anthropometric components may be predictive factors of a new conceptual modality estimating concomitant cardiorespiratory fitness beyond their traditional health-related indications.

Plasma adiponectin levels are correlated with body composition, metabolic profiles, and mitochondrial markers in individuals with chronic spinal cord injury

STUDY DESIGN

Cross-sectional design.

OBJECTIVES

This study examined the relationships between circulating adiponectin levels, body composition, metabolic profile, and measures of skeletal muscle mitochondrial enzyme activity and biogenesis.

SETTINGS

Clinical Research in a Medical Center.

METHODS

Plasma adiponectin was quantified in 19 individuals with chronic spinal cord injury (SCI). Body composition was evaluated by dual x-ray absorptiometry and magnetic resonance imaging. Metabolic profile was assessed by basal metabolic rate (BMR), oxygen uptake (VO₂), and intravenous glucose tolerance testing. Mitochondrial enzyme activity of skeletal muscle was obtained by spectrophotometric assays and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and 5' AMP-activated protein kinase (AMPK) protein expression was assessed by Western blots.

RESULTS

Adiponectin was negatively related to both total and regional fat mass and positively related to lean mass and muscle mass. Furthermore, there were positive relationships between adiponectin and BMR (r = 0.52, P = 0.02) and VO₂ (r = 0.73, P = 0.01). Furthermore, adiponectin was positively related to citrate synthase (r = 0.68, P = 0.002) and complex III activity (r = 0.57, P = 0.02). The relationships between adiponectin and body composition remained significant after accounting for age. The relationships between adiponectin, metabolic profile, and markers of mitochondria mass and activity were influenced by age.

CONCLUSIONS

The study demonstrated that adiponectin is closely related to body composition and metabolic profile in persons with SCI and further supports mechanistic studies suggesting that adiponectin may stimulate mitochondrial biogenesis.

Health status of regularly physically active persons with spinal cord injury

Study design

A non-controlled cross-sectional study.

Objectives

To make a descriptive examination of health status in persons with paraplegia and tetraplegia who exercise regularly according to Canadian guidelines.

Settings

Sunnaas Rehabilitation Hospital and the Norwegian School of Sport Sciences.

Methods

Eighteen persons (men/women = 9/9), aged 41‒72 years with spinal cord injury (SCI), who exercise regularly were included. Post-injury years ranged from 4 to 48 years. Clinical examination of body composition, bone mineral density (BMD), forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), diffusion capacity (DL_CO), cardiorespiratory fitness (VO_2max), and self-reported quality of life (QOL) obtained by questionnaire was performed. Lung function results are presented as % predicted and VO_2max as absolute values relative to body weight. All results are given as median and range.

Results

Persons with paraplegia (n = 13) were defined as overweight with fat mass 42% (25‒51). BMD 1.047 g cm⁻² (0.885‒1.312) was within normal range. FVC 95% predicted (60‒131), FEV₁ 90% predicted (61‒119), DL_CO 77% predicted (56‒103), and VO_2max 16.66 ml kg⁻¹ min⁻¹ (12.15‒25.28) defined good aerobic capacity according to age controlled reference values (18). Persons with tetraplegia (n = 5) were slightly overweight with fat mass 35% (26‒47). BMD 1.122 g cm⁻² (1.095‒1.299) was within normal range. FVC 72% predicted (46‒91), FEV₁ 75% predicted (43‒83), DL_CO 67% predicted (56‒84), and VO_2max 16.70 ml kg⁻¹ min⁻¹ (9.91‒21.01) defined excellent aerobic capacity according to reference values (18). QOL was ranked as median 7.5 (0‒10 scale).

Conclusions

Persons with SCI who exercise regularly following the Canadian guidelines responded with rather positive associations for health outcomes. Additional research is needed to strengthen our findings.

Body System Effects of a Multi-Modal Training Program Targeting Chronic, Motor Complete Thoracic Spinal Cord Injury

The safety and efficacy of pharmacological and cellular transplantation strategies are currently being evaluated in people with spinal cord injury (SCI). In studies of people with chronic SCIs, it is thought that functional recovery will be best achieved when drug or cell therapies are combined with rehabilitation protocols. However, any functional recovery attributed to the therapy may be confounded by the conditioned state of the body and by training-induced effects on neuroplasticity. For this reason, we sought to investigate the effects of a multi-modal training program on several body systems. The training program included body-weight-supported treadmill training for locomotion, circuit resistance training for upper body conditioning, functional electrical stimulation for activation of sublesional muscles, and wheelchair skills training for overall mobility. Eight participants with chronic, thoracic-level, motor-complete SCI completed the 12-week training program. After 12 weeks, upper extremity muscular strength improved significantly for all participants, and some participants experienced improvements in function, which may be explained by increased strength. Neurological function did not change. Changes in pain and spasticity were highly variable between participants. This is the first demonstration of the effect of this combination of four training modalities. However, balancing participant and study-site burden with capturing meaningful outcome measures is also an important consideration.

A lifestyle intervention program for successfully addressing major cardiometabolic risks in persons with SCI: a three-subject case series

INTRODUCTION

This study is a prospective case series analyzing the effects of a comprehensive lifestyle intervention program in three patients with chronic paraplegia having major risks for the cardiometabolic syndrome (CMS).

CASE PRESENTATION

Individuals underwent an intense 6-month program of circuit resistance exercise, nutrition using a Mediterranean diet and behavioral support, followed by a 6-month extension (maintenance) phase involving minimal support. The primary goal was a 7% reduction of body mass. Other outcomes analyzed insulin resistance using the HOMA-IR model, and plasma levels of fasting triglycerides and high-density lipoprotein cholesterol. All participants achieved the goal for 7% reduction of body mass and maintained the loss after the MP. Improvements were observed in 2/3 subjects for HOMA-IR and high-density lipoprotein cholesterol. All participants improved their risk for plasma triglycerides.

DISCUSSION

We conclude, in a three-person case series of persons with chronic paraplegia, a lifestyle intervention program involving circuit resistance training, a calorie-restrictive Mediterranean-style diet and behavioral support, results in clinically significant loss of body mass and effectively reduced component risks for CMS and diabetes. These results were for the most part maintained after a 6-month MP involving minimal supervision.

Teleexercise for Persons With Spinal Cord Injury: A Mixed-Methods Feasibility Case Series

Background

Spinal cord injury (SCI) results in significant loss of function below the level of injury, often leading to restricted participation in community exercise programs. To overcome commonly experienced barriers to these programs, innovations in technology hold promise for remotely delivering safe and effective bouts of exercise in the home.

Objective

To test the feasibility of a remotely delivered home exercise program for individuals with SCI as determined by (1) implementation of the intervention in the home; (2) exploration of the potential intervention effects on aerobic fitness, physical activity behavior, and subjective well-being; and (3) acceptability of the program through participant self-report.

Methods

Four adults with SCI (mean age 43.5 [SD 5.3] years; 3 males, 1 female; postinjury 25.8 [SD 4.3] years) completed a mixed-methods sequential design with two phases: an 8-week intervention followed by a 3-week nonintervention period. The intervention was a remotely delivered aerobic exercise training program (30-45 minutes, 3 times per week). Instrumentation included an upper body ergometer, tablet, physiological monitor, and custom application that delivered video feed to a remote trainer and monitored and recorded exercise data in real time. Implementation outcomes included adherence, rescheduled sessions, minutes of moderate exercise, and successful recording of exercise data. Pre/post-outcomes included aerobic capacity (VO₂ peak), the Physical Activity Scale for Individuals with Physical Disabilities (PASIPD), the Satisfaction with Life Scale (SWLS), and the Quality of Life Index modified for spinal cord injury (QLI-SCI). Acceptability was determined by participant perceptions of the program features and impact, assessed via qualitative interview at the end of the nonintervention phase.

Results

Participants completed all 24 intervention sessions with 100% adherence. Out of 96 scheduled training sessions for the four participants, only 8 (8%) were makeup sessions. The teleexercise system successfully recorded 85% of all exercise data. The exercise program was well tolerated by all participants. All participants described positive outcomes as a result of the intervention and stated that teleexercise circumvented commonly reported barriers to exercise participation. There were no reported adverse events and no dropouts.

Conclusion

A teleexercise system can be a safe and feasible option to deliver home-based exercise for persons with SCI. Participants responded favorably to the intervention and valued teleexercise for its ability to overcome common barriers to exercise. Study results are promising but warrant further investigation in a larger sample.

Comparison of 1- Versus 3-Minute Stage Duration During Arm Ergometry in Individuals With Spinal Cord Injury

OBJECTIVE

To investigate the effect of stage duration on peak physiological response to arm ergometry incremental exercise testing in individuals with spinal cord injury or disease (SCI/D) in support of developing a more individualized approach to testing.

DESIGN

Parallel reliability study.

SETTING

University research laboratory.

PARTICIPANTS

Individuals with SCI/D (N=38) performed 2 peak oxygen consumption assessments comprised of 1-minute or 3-minute stages on 1 day.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Heart rate and oxygen consumption were recorded continuously from baseline through recovery. Every 1 minute or 3 minutes, resistance increased at an individualized level, and participants continued until volitional fatigue. The highest 30-second average was selected as peak oxygen consumption (Vo₂peak) and peak heart rate. The highest workload achieved for ≥30 seconds was recorded as peak power output (PO).

RESULTS

Intraclass correlation coefficients (ICCs) were >.95 for the following variables: absolute Vo₂peak (mean ± SD, 1min: 1.2±0.7, 3min: 1.2±.62L/min; 95% CI, .91-.98), relative Vo₂peak (mean ± SD, 1min: 16.6±9.4, 3min: 15.8±8.0mL/kg/min; 95% CI, .90-.98), absolute peak PO (mean ± SD, 1min: 61±41, 3min: 66±41W; 95% CI, .92-.98), and relative peak PO (mean ± SD, 1min: .80±56, 3min: .90±.55W/kg; 95% CI, .91-.98). There was no significant difference in peak heart rate between 3 minutes (132±27 beats per minute [bpm]) and 1 minute (130±28 bpm); however, the ICC lower limit was <.75 (0.67-0.90). Total test time was significantly longer in the 3-minute (8:17±2:52min:s) than in the 1-minute (6:29±2:21min:s) protocol.

CONCLUSIONS

For measuring peak physiological values in an incremental arm ergometry test, stage duration is of little consequence because similar values were obtained for the main outcome measures in both protocols.

Effects of aerobic exercise training on fitness and walking-related outcomes in ambulatory individuals with chronic incomplete spinal cord injury

Study Design

Single group, pretest-posttest study.

Objectives

To determine the effects of a non-task-specific, voluntary, progressive aerobic exercise training (AET) intervention on fitness and walking-related outcomes in ambulatory adults with chronic motor-incomplete SCI.

Setting

Rehabilitation research center.

Methods

Ten ambulatory individuals (50% female; 57.94 ± 9.33 years old; 11.11 ± 9.66 years post injury) completed voluntary, progressive moderate-to-vigorous intensity AET on a recumbent stepper three days per week for six weeks. The primary outcome measures were aerobic capacity (VO_2peak) and self-selected overground walking speed (OGWS). Secondary outcome measures included: walking economy, six-minute walk test (6MWT), daily step counts, Walking Index for Spinal Cord Injury (WISCI-II), Dynamic Gait Index (DGI), and Berg Balance Scale (BBS).

Results

Nine participants completed all testing and training. Significant improvements in aerobic capacity (P=0.011), OGWS (P=0.023), the percentage of VO_2peak utilized while walking at self-selected speed (P=0.03), and daily step counts (P=0.025) resulted following training.

Conclusions

The results indicate that total-body, voluntary, progressive AET is safe, feasible, and effective for improving aerobic capacity, walking speed, and select walking-related outcomes in an exclusively ambulatory SCI sample. This study suggests the potential for non-task-specific aerobic exercise to improve walking following incomplete SCI and builds a foundation for further investigation aimed at the development of exercise based rehabilitation strategies to target functionally limiting impairments in ambulatory individuals with chronic SCI.

Exercise self-efficacy and the relation with physical behavior and physical capacity in wheelchair-dependent persons with subacute spinal cord injury

Background

Since physical activity and exercise levels are known to be generally low in persons with spinal cord injury (SCI), there seems to be a need for intervention. Exercise self-efficacy (ESE), the confidence persons have in their ability to be physically active and exercise, is an important and modifiable predictor of physical behavior. The goal of this study was to 1) describe ESE in persons with subacute SCI, 2) to assess ESE in subgroups based on demographic and lesion characteristics, and 3) to explore the relation between ESE and physical behavior and physical capacity.

Methods

Thirthy-seven persons with subacute SCI who are wheelchair dependent participated. Participants completed the Exercise Self-Efficacy Scale. We recorded age and lesion characteristics, measured physical behavior (physical activity, motility and sedentary day time, n = 35) with an accelerometer-based activity monitor and measured physical capacity (peak power output, n = 28 and peak oxygen uptake, n = 24) during a maximal hand-cycling test. Measurements were performed 2 months prior to discharge from inpatient rehabilitation. Mann-Whitney tests were used to test for differences between subgroups based on age and lesion characteristics and spearman correlations were used to assess the relation between ESE and physical activity and physical capacity.

Results

Persons with tetraplegia had lower ESE compared to persons with paraplegia (Z = −1.93, p = 0.05). No differences in ESE were found between subgroups based on age and motor completeness of the lesion. In persons with paraplegia, ESE was positively related to peak power output (ρ = 0.58, p = 0.02). The relation of ESE with wheeled physical activity was ρ = 0.36, p = 0.09.

Conclusions

In persons with SCI who are dependent on a manual wheelchair, lesion level when categorized as paraplegic and tetraplegic affected ESE whereas age categories and completeness categories did not. Persons with tetraplegia were found to have lower confidence with regard to physical activity and exercise indicating that this subgroup can benefit from extra attention in the promotion of physical activity and exercise. In persons with paraplegia, ESE seemed to be lower in persons with less peak power output and less daily physical activity.