The relationship between perceived exertion and physiologic indicators of stress during graded arm exercise in persons with spinal cord injuries

Consensus-Based Recommendations for Designing, Delivering, Evaluating, and Reporting Exercise Intervention Research Involving People Living With a Spinal Cord Injury

OBJECTIVES

To establish recommendations for designing, delivering, evaluating, and reporting exercise intervention research to improve fitness-related outcomes in people living with spinal cord injury (PwSCI).

DESIGN

International consensus process.

SETTING

(1) An expert panel was established consisting of 9 members of the governing panel of the International Spinal Cord Society Physical Activity Special Interest Group and 9 additional scientists who authored or co-authored ≥1 exercise randomized controlled trial paper involving PwSCI. (2) We invited the panelists to draft an outline of the recommendations for 1 intervention component. (3) The panel reviewed the draft outlines and determined whether they fit the scope and objectives of the project, whether they were evidence-based, and whether they were sufficiently detailed. (4) We interviewed 7 PwSCI who had participated in ≥1 exercise trial to gather insights on their experiences within the trials, what they liked, and what they would change. (5) A first draft of the recommendations was approved by the panel and circulated to the general members of the International Spinal Cord Society Physical Activity Special Interest Group to gather their suggestions and opinions via an online survey. (6) The member feedback was used to revise the recommendations and panel members approved a final version.

PARTICIPANTS

N/A.

INTERVENTIONS

N/A.

MAIN OUTCOME MEASURE(S)

N/A.

RESULTS

We generated 33 recommendations regarding participant recruitment, study sample size determination, outcome measurement, potential confounders, exercise intervention prescription and delivery, supporting adherence to the intervention, monitoring and reporting adherence and retention, fidelity of the delivery of the intervention, monitoring and reporting adverse events, study design, and registration of study protocol and preparation of a protocol paper.

CONCLUSIONS

International experts have come to consensus on recommendations for conducting exercise intervention research involving PwSCI. Adopting these recommendations will increase the quality of the research and the overall certainty of the evidence regarding the effects of exercise on health outcomes in PwSCI.

Assessment of Cardiac Autonomic Function by Short-Term Sensor-Based and Long-Term Heart Rate Variability Analyses in Individuals with Spinal Cord Injury After Long-Term Table Tennis Training

This study aimed to examine the acute and chronic effects of an exercising table tennis program on cardiac Autonomic Nervous System (ANS) and functional capacity in people with tetraplegia. Twenty males with tetraplegia (C6-C7), with a mean age of 38.50 ± 4.04 years old, were randomly assigned into two equal groups: A, who followed a 6-month exercise training program with table tennis 3 times per week, and B, who remained untrained. Additionally, 11 healthy sedentary men (group C) with a mean age of 39.71 ± 5.87 years old participated in the study as healthy controls. At baseline, all participants underwent a short-term (5 min) and a long-term (24 h ambulatory) ECG monitoring to evaluate the heart rate variability (HRV) indices and a maximal arm ergometric and dynamometric testing of the upper limbs. Moreover, the acute cardiac autonomic responses to maximal arm cycle exercise test were evaluated by Polar S810i sensor chest strap. At the end of the 6-month study, all parameters were revaluated only in groups A and B. At baseline, there was no statistically significant difference between the two patient groups. However, intra-group changes at the end of the 6-month study regarding the 24-h HRV monitoring indicated that group A statistically increased the standard deviation of R-R intervals (SDNN) by 13.9% (p = 0.007), the standard deviation of R-R intervals calculated every 5 min (SDANN) by 8.4% (p = 0.007), the very low frequency (VLF) by 7.1% (p = 0.042), and the low frequency [LF (ms2)] by 10.5% (p = 0.009), which almost reached the levels of group C. Favorable improvements were also noticed at the end of the study for group A in maximal exercise time of the upper limbs by 80.4% (p < 0.001) and maximal strength of the right hand by 27.8% (p < 0.001). Linear regression analysis after training showed that maximal exercise time was positively correlated with SDNN (r = 0.663, p = 0.036) and with LF (ms2) (r = 0.623, p = 0.045). Our results indicate that a 6-month table tennis training program is efficient and can improve cardiac ANS activity mainly by increasing sympathovagal balance.

Effect of spinal cord injury on the skin temperature of different regions of interest during a graded exercise test in a moderate temperature environment

The gradient between core and skin temperature is a relevant factor in heat exchange between the human body and the environment, but people with spinal cord injury (SCI), due to their autonomic dysfunction, have impaired mechanisms that condition skin temperature response. This study aimed to determine how SCI affects skin temperature response in different ROIs during a graded exercise test in a moderate temperature environment. 32 participants were included in the study [SCI (N = 16); Non-SCI (N = 16)]. A graded exercise test was conducted on an arm crank ergometer, with a staged duration of 3 min separated by 1 min of rest. Skin temperature was measured using infrared thermography at rest, after each interval and during recovery. Individuals with SCI exhibited lower skin temperature in the anterior leg during exercise than Non-SCI (p < 0.001). During recovery, SCI athletes experienced a lower skin temperature restoration in the anterior arm, posterior arm and anterior leg (p < 0.05). The anterior leg is an interesting region to measure during exercise in people with SCI for assessing the physiological effect of the injury, probably for the autonomic dysfunction in skin temperature regulation, but the effect observed during recovery in the arms suggests the presence of different mechanisms involved in skin temperature regulation.

Guidelines for chronic pain in adult spinal cord injury population: Scoping review

Background

Chronic pain among survivors of spinal cord injury (SCI) hurts physical and mental health. Persons with SCI have demonstrated dissatisfaction with the management of their chronic pain.

Objectives

This study aimed to identify existing clinical practice guidelines for chronic pain in the SCI population.

Method

A scoping review was conducted across various databases available at the University of the Western Cape, in addition to guideline clearing houses (BioMedCentral, Cambridge Journals Online, CINAHL, Cochrane Library, Medline [EbscoHost], Medline [Pubmed], Sabinet Reference, SAGE Journals Online, ScienceDirect, SCOPUS, Wiley Online Library, Springerlink, PubMed, Guideline Central, and Agency for Healthcare Research and Quality). The population consisted of adults with SCI, and the interventions that were included were pharmacological and nonpharmacological management of chronic pain. Guidelines that met the inclusion criteria were critically appraised by two reviewers from this study using the AGREE II instrument. Inter-rater reliability was calculated using SPSS 27, and Cohen's kappa coefficients were established.

Results

Five articles were included in the data extraction, analysis and appraisal. Two guidelines were rated as high quality, according to the AGREE II tool. In addition, most guidelines focused on neuropathic pain (NeuP) and only one guideline included nociceptive pain and NeuP.

Conclusion

One guideline met the objectives of this scoping review.

Clinical implications

Guidelines developed in the future should include a screening tool to identify the specific type of pain and distinguish peripheral NeuP from central NeuP.

Assessing the efficacy of duration and intensity prescription for physical activity in mitigating cardiometabolic risk after spinal cord injury

PURPOSE OF REVIEW

Spinal cord injury (SCI) heightens susceptibility to cardiometabolic risk (CMR), predisposing individuals to cardiovascular disease. This monograph aims to assess the optimal duration and intensity of physical activity (PA) for managing CMR factors, particularly obesity, after SCI and provide modality-specific PA durations for optimal energy expenditure.

RECENT FINDINGS

PA guidelines recommend at least 150 min/week of moderate-intensity activity. However, non-SCI literature supports the effectiveness of engaging in vigorous-intensity PA (≥6 METs) and dedicating 250-300 min/week (≈2000 kcal/week) to reduce CMR factors. Engaging in this volume of PA has shown a dose-response relationship, wherein increased activity results in decreased obesity and other CMR factors in persons without SCI.

SUMMARY

To optimize cardiometabolic health, individuals with SCI require a longer duration and higher intensity of PA to achieve energy expenditures comparable to individuals without SCI. Therefore, individuals with SCI who can engage in or approach vigorous-intensity PA should prioritize doing so for at least 150 min/wk. At the same time, those unable to reach such intensities should engage in at least 250-300 min/week of PA at a challenging yet comfortable intensity, aiming to achieve an optimal intensity level based on their abilities. Given the potential to decrease CMR after SCI, increasing PA duration and intensity merits careful consideration in future SCI PA directives.

Physiological and Perceptual Responses in Spinal Cord Injury Handcyclists During an Endurance Interval Training: The Role of Critical Speed

OBJECTIVE

This study sought to determine the physiological (oxygen uptake, heart rate, and blood lactate concentration) and perceptual (rating of perceived exertion) responses during an endurance interval training at the critical speed in elite handcyclists with spinal cord injury.

DESIGN

Eight handcyclists performed an incremental test, three tests to exhaustion at a constant speed to determine critical speed, and the endurance interval training. The endurance interval training consisted of 6 × 5 mins at the individualized critical speed, with passive recovery of 50 secs. All testing was performed using their own handcycles on an oversized motorized treadmill. Physiological and perceptual responses were assessed during the incremental and endurance interval training tests.

RESULTS

There was no significant difference in average oxygen uptake from the first to the sixth repetition. The mean ∆[La-]10_last between the 10th to the 30th minute of the exercise was -0.36 mmol·l-1, and no difference was detected from the first to the sixth repetition. The heart rate also remained stable during endurance interval training, whereas rating of perceived exertion increased significantly throughout the session.

CONCLUSIONS

Repetitions of 5 mins at the critical speed in elite handcyclists are associated with cardiorespiratory and lactate steady state, whereas the perceived exertion increased systematically.

Physiological and perceptual responses during walking at set and preferred pace in normal and overweight adults

BACKGROUND

This study aimed to investigate the influence of body weight, exercise modality, and pace on physiological and perceptual responses to determine the relation between perceptual and physiological responses.

METHODS

Aerobically untrained, normal weight, and overweight males and females participated. Participants were randomly assigned to one exercise condition for a 1-mile walk.

RESULTS

Prescribed pace resulted in a greater physiological stress than self-selected pace (all p < 0.001) through blood lactate (1.3 ± 0.4 vs 1.7 ± 0.5 mmol), systolic blood pressure (128.9 ± 10.3 vs 139.2 ± 13.2 mmHg), heart rate recovery (2.1 ± 1.7 vs 4.5 ± 2.6 min), oxygen consumption (15.1 ± 2.6 vs 18.1 ± 3.6 ml/kg/min), heart rate (111.7 ± 16.6 vs 134.4 ± 8.3 bpm), and energy expenditure (5.5 ± 1.4 vs 6.8 ± 1.7 kcal/min). Overweight individuals exhibited higher values than normal weight for heart rate (113 ± 8.8 vs 125.5 ± 13.2 bpm, p < 0.001), percentage of max heart rate (60.7 vs 69.0%, p < 0.001), percent of VO2peak (42.2 vs 55.6%, p < 0.001), and total energy expenditure (100.9 ± 27.4 vs 114.1 ± 33.5 kcal, p = 0.022). Greater perceived effort was seen on a treadmill (6.3 ± 0.5 vs 12.5 ± 2.0 RPE, p < 0.001) and at prescribed pace (6.5 ± 1.1 vs 8.9 ± 1.9 RPE, p < 0.001).

CONCLUSION

A novel finding of this study was the increased physiological stress and perception of effort on a treadmill and at a prescribed pace, while total energy expenditure showed no significant differences. This could indicate an unfavorable perception and less affective response to the treadmill modality. These results indicate exercise at self-selected pace in preferred environments promotes enjoyable experiences with similar health benefits as those during prescribed higher intensity exercise.

The ability of heart rate or perceived exertion to predict oxygen uptake varies across exercise modes in persons with tetraplegia

STUDY DESIGN

Descriptive study.

OBJECTIVES

To examine grouped and intra-individual relationships between 1) exercise intensity and heart rate (EI-HR); 2) EI and oxygen uptake (EI-VO₂); 3) VO₂ and HR (VO₂-HR); and 4) perceived exertion and VO₂ (PE-VO₂) in persons with tetraplegia (C4/5-C8) during different modes of exercise.

SETTING

Community in Winnipeg, Canada.

METHODS

Participants exercised at 3 graded intensities during arm ergometry (ERG), wheeling indoors on cement (MWC), or hand-cycling outdoors (HC). EI (Watts, km/hr) and VO₂, HR and PE were recorded.

RESULTS

22 persons completed ERG, 14/22 also completed MWC and 5/22 completed ERG, MWC and HC. Regression analysis of grouped data showed a significant relationship between EI-VO₂ but not for EI-HR or HR-VO₂. Intra-individual analyses showed a strong correlation (r or ρ > 0.7) for VO₂-HR for 16/22 during ERG. In the participants completing multiple exercise modes, a strong VO₂-HR relationship was present in 12/14 in ERG, but in only 6/14 in MWC. The 5 persons exercising with all 3 modes had a strong HR-VO₂ relationship in 5/5 for ERG, 2/5 in MWC and 1/5 in HC. A strong relationship for PE-VO₂ was observed in a higher proportion of participants (versus HR-VO₂) during MWC (9/14) and HC (2/4).

CONCLUSION

Within the same individual, the HR-VO₂ relationship varies across modes, despite exercising over similar ranges of steady-state VO₂. HR appears less able to predict VO₂ compared to PE. Based on these new findings, systematic investigation of the HR-VO₂ relationship across modes of exercise in tetraplegia is warranted.

Cardiorespiratory Responses to 10 Weeks of Exoskeleton-Assisted Overground Walking Training in Chronic Nonambulatory Patients with Spinal Cord Injury

Exercise intensity of exoskeleton-assisted walking in patients with spinal cord injury (SCI) has been reported as moderate. However, the cardiorespiratory responses to long-term exoskeleton-assisted walking have not been sufficiently investigated. We investigated the cardiorespiratory responses to 10 weeks of exoskeleton-assisted walking training in patients with SCI. Chronic nonambulatory patients with SCI were recruited from an outpatient clinic. Walking training with an exoskeleton was conducted three times per week for 10 weeks. Oxygen consumption and heart rate (HR) were measured during a 6-min walking test at pre-, mid-, and post-training. Exercise intensity was determined according to the metabolic equivalent of tasks (METs) for SCI and HR relative to the HR reserve (%HRR). Walking efficiency was calculated as oxygen consumption divided by walking speed. The exercise intensity according to the METs (both peak and average) corresponded to moderate physical activity and did not change after training. The %HRR demonstrated a moderate (peak %HRR) and light (average %HRR) exercise intensity level, and the average %HRR significantly decreased at post-training compared with mid-training (31.6 ± 8.9% to 24.3 ± 7.3%, p = 0.013). Walking efficiency progressively improved after training. Walking with an exoskeleton for 10 weeks may affect the cardiorespiratory system in chronic patients with SCI.

Load Auditory Feedback Boosts Crutch Usage in Subjects With Central Nervous System Lesions: A Pilot Study

Background: Crutches are the most common walking aids prescribed to improve mobility in subjects with central nervous system (CNS) lesions. To increase adherence to the appropriate level of crutch usage, providing load-related auditory feedback (aFB) may be a useful approach. We sensorized forearm crutches and developed a custom software to provide aFB information to both user and physical therapist (PhT).

Aim: Evaluate aFB effects on load control during gait by a self-controlled case series trial.

Methods: A single experimental session was conducted enrolling 12 CNS lesioned participants. Load on crutch was recorded during 10 Meter Walk Test performed with and without aFB. In both cases, crutch load data, and gait speed were recorded. Usability and satisfaction questionnaires were administered to participants and PhTs involved.

Results: Reliable data were obtained from eight participants. Results showed that compared to the no FB condition, aFB yielded a significant reduction in the mean load on the crutches during gait (p = 0.001). The FB did not influence gait speed or fatigue (p > 0.05). The experience questionnaire data indicated a positive experience regarding the use of aFB from both participants' and PhTs' perspectives.

Conclusion: aFB significantly improves compliance with crutch use and does not affect gait speed or fatigue by improving the load placed on crutches. The FB is perceived by users as helpful, safe, and easy to learn, and does not interfere with attention or concentration while walking. Furthermore, the PhTs consider the system to be useful, easy to learn and reliable.

Effect of wheelchair-modified rowing exercise on cardiometabolic risk factors in spinal cord injured wheelchair users: protocol for a randomised controlled trial

INTRODUCTION

Cardiovascular and metabolic diseases are a growing concern for individuals with spinal cord injury (SCI). Physical inactivity contributes to cardiometabolic morbidity and mortality in the SCI population. However, previous studies have shown mixed results regarding the effects of exercise on cardiometabolic risk factors in individuals with SCI. This discrepancy could be influenced by insufficient exercise stimuli. Recent guidelines recommend 30 min of moderate-to-vigorous intensity aerobic exercise, three times per week, for improvement in cardiometabolic health in individuals with SCI. However, to date, no studies have implemented an exercise intervention matching the new recommendations to examine the effects on cardiometabolic risk factors. Therefore, the primary objective of this study is to determine the effects of 12 weeks of wheelchair user-modified upper-body rowing exercise on both traditional (constituents of the metabolic syndrome) and novel (eg, vascular structure and function) cardiometabolic risk factors in manual wheelchair users with SCI.

METHODS AND ANALYSIS

A randomised controlled trial will compare 12 weeks of upper-body rowing exercise, 30 min three times per week, with a control group continuing their normal lifestyle. Outcome measurements will be performed immediately before (baseline), after 6 weeks (halfway), 12 weeks of training (post) and 6 months after the termination of the intervention period (follow-up). Outcomes will include inflammatory (eg, C reactive protein) and metabolic biomarkers determined from venous blood (with serum fasting insulin as primary outcome), body composition, arterial blood pressure, cardiorespiratory fitness level, brachial artery vascular structure and function and autonomic nervous system function.

ETHICS AND DISSEMINATION

This trial is reported to the Danish Data Protection Agency (J.nr. 2019-899/10-0406) and approved by the Committees on Health Research Ethics in The North Denmark Region on 12 December 2019 (J.nr. N-20190053). The principal investigator will collect written informed consent from all participants prior to inclusion. Irrespective of study outcomes, the results will be submitted to peer-reviewed scientific journals for publication.

TRIAL REGISTRATION NUMBER

NCT04390087.

Neuromuscular Controller Embedded in a Powered Ankle Exoskeleton: Effects on Gait, Clinical Features and Subjective Perspective of Incomplete Spinal Cord Injured Subjects

Powered exoskeletons are among the emerging technologies claiming to assist functional ambulation. The potential to adapt robotic assistance based on specific motor abilities of incomplete spinal cord injury (iSCI) subjects, is crucial to optimize Human-Robot Interaction (HRI). Achilles, an autonomous wearable robot able to assist ankle during walking, was developed for iSCI subjects and utilizes a NeuroMuscular Controller (NMC). NMC can be used to adapt robotic assistance based on specific residual functional abilities of subjects. The main aim of this pilot study was to analyze the effects of the NMC-controlled Achilles, used as an assistive device, on chronic iSCI participants' performance, by assessing gait speed during 10-session training of robot-aided walking. Secondary aims were to assess training impact on participants' motion, clinical and functional features and to evaluate subjective perspective in terms of attitude towards technology, workload, usability and satisfaction. Results showed that 5 training sessions were necessary to significantly improve robot-aided gait speed on short paths and consequently to optimize HRI. Moreover, the training allowed participants who initially were not able to walk for 6 minutes, to improve gait endurance during Achilles-aided walking and to reduce perceived fatigue. Improvements were obtained also in gait speed during free walking, thus suggesting a potential rehabilitative impact, even if Achilles-aided walking was not faster than free walking. Participants' subjective evaluations indicated a positive experience.

Intensity of physical activity as a percentage of peak oxygen uptake, heart rate and Borg RPE in motor-complete para- and tetraplegia

Objective

The aims were to describe VO_2peak, explore the potential influence of anthropometrics, demographics and level of physical activity within each cohort; b) to define common, standardized activities as percentages of VO_2peak and categorize these as light, moderate and vigorous intensity levels according to present classification systems, and c) to explore how clinically accessible methods such as heart-rate monitoring and Borg rating of perceived exertion (RPE) correlate or can describe light, moderate and vigorous intensity levels.

Design

Cross sectional.

Setting

Rehabilitation facility and laboratory environment.

Subjects

Sixty-three individuals, thirty-seven (10 women) with motor-complete paraplegia (MCP), T7-T12, and twenty-six (7 women) with motor-complete tetraplegia (MCT), C5-C8.

Interventions

VO_2peak was obtained during a graded peak test until exhaustion, and oxygen uptake during eleven different activities was assessed and categorized using indirect calorimetry.

Main outcome measures

VO_2peak, Absolute and relative oxygen consumption, Borg RPE.

Results

Absolute VO_2peak was significantly higher in men than in women for both groups, with fairly small differences in relative VO_2peak. For MCP sex, weight and time spent in vigorous-intensity activity explained 63% of VO_2peak variance. For MCT sex and time in vigorous-intensity activity explained 55% of the variance. Moderate intensity corresponds to 61–72% HR_peak and RPE 10–13 for MCP vs. 71–79% HR_peak, RPE 13–14 for MCT.

Conclusion

Using current classification systems, eleven commonly performed activities were categorized in relative intensity terms, (light, moderate and vigorous) based on percent of VO_2peak, HR_peak and Borg RPE. This categorization enables clinicians to better guide persons with SCI to meet required physical activity levels.

Effect of overground locomotor training on ventilatory kinetics and rate of perceived exertion in persons with cervical motor-incomplete spinal cord injury

Study design

Pre-post, pilot study.

Objectives

To characterize ventilatory (VE) responses to exercise following warm-up walking in individuals with chronic incomplete spinal cord injury (iSCI) during constant work rate (CWR) exercise. Secondarily, to investigate VE and tidal volume (VT) variability, and ratings of perceived exertion (RPE) before and after overground locomotor training (OLT).

Setting

Research laboratory.

Methods

A 6-min CWR walking bout at preferred pace was used as a warm-up followed by 6 min of rest and a second 6-min CWR bout at above preferred walking pace. The second CWR bout was analyzed. Breath-by-breath ventilatory data were examined using a curvilinear least squares fitting procedure with a mono-exponential model. VE and VT variability was calculated as the difference between the observed and predicted values and RPE was taken every 2 min.

Results

Participants (n = 3, C4-C5) achieved a hyperpneic response to exercise in VE and VT. OLT resulted in faster ventilatory kinetics and reductions of 24 and 29% for VE and VT variability, respectively. A 30% reduction in RPE was concurrent with the reductions in ventilatory variability.

Conclusions

OLT may improve ventilatory control during CWR in patients with cervical motor-iSCI. These data suggest that in some participants with iSCI, ventilation may influence RPE during walking. Future research should investigate mechanisms of ventilatory variability and its implications in walking performance in patients with iSCI.

High-Intensity Variable Stepping Training in Patients With Motor Incomplete Spinal Cord Injury: A Case Series

BACKGROUND AND PURPOSE

Previous data suggest that large amounts of high-intensity stepping training in variable contexts (tasks and environments) may improve locomotor function, aerobic capacity, and treadmill gait kinematics in individuals poststroke. Whether similar training strategies are tolerated and efficacious for patients with other acute-onset neurological diagnoses, such as motor incomplete spinal cord injury (iSCI), is unknown. Individuals with iSCI potentially have greater bilateral impairments. This case series evaluated the feasibility and preliminary short- and long-term efficacy of high-intensity variable stepping practice in ambulatory participants for more than 1 year post-iSCI.

CASE SERIES DESCRIPTION

Four participants with iSCI (neurological levels C5-T3) completed up to 40 one-hour sessions over 3 to 4 months. Stepping training in variable contexts was performed at up to 85% maximum predicted heart rate, with feasibility measures of patient tolerance, total steps/session, and intensity of training. Clinical measures of locomotor function, balance, peak metabolic capacity, and gait kinematics during graded treadmill assessments were performed at baseline and posttraining, with more than 1-year follow-up.

OUTCOMES

Participants completed 24 to 40 sessions over 8 to 15 weeks, averaging 2222 ± 653 steps per session, with primary adverse events of fatigue and muscle soreness. Modest improvements in locomotor capacity where observed at posttraining, with variable changes in lower extremity kinematics during treadmill walking.

DISCUSSION

High-intensity, variable stepping training was feasible and tolerated by participants with iSCI although only modest gains in gait function or quality were observed. The utility of this intervention in patients with more profound impairments may be limited.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A200).

Management of pain in individuals with spinal cord injury: Guideline of the German-Speaking Medical Society for Spinal Cord Injury

Introduction: Pain is a prominent complication in spinal cord injury (SCI). It can either occur as a direct or as an indirect consequence of SCI and it often heavily influences the quality of life of affected individuals. In SCI, nociceptive and neuropathic pain can equally emerge at the same time above or below the level of injury. Thus, classification and grading of pain is frequently difficult. Effective treatment of SCI-related pain in general and of neuropathic pain in particular is challenging. Current treatment options are sparse and their evidence is considered to be limited. Considering these aspects, a clinical practice guideline was developed as basis for an optimized, comprehensive and standardized pain management in SCI-related pain.

Methods: The German-Speaking Medical Society for Spinal Cord Injury (Deutschsprachige Medizinische Gesellschaft für Paraplegiologie – DMGP) developed a clinical practice guideline that received consensus from seven further German-speaking medical societies and one patient organization. The evidence base from clinical trials and meta-analyses was summarized and subjected to a structured consensus-process in accordance with the regulations of the Association of Scientific Medical Societies in Germany (AWMF) and the methodological requirements of the “German instrument for methodological guideline appraisal”.

Results: This consensus-based guideline (S2k classification according to the AWMF guidance manual and rules) resulted in seven on-topic statements and 17 specific recommendations relevant to the classification, assessment and therapy of pain directly or indirectly caused by SCI. Recommended therapeutic approaches comprise pharmacological (e.g. nonsteroidal anti-inflammatory drugs or anticonvulsants) and non-pharmacological (e.g. physical activity or psychotherapeutic techniques) strategies for both nociceptive and neuropathic pain.

Discussion: Assessment of SCI-related pain is standardized and respective methods in terms of examination, classification and grading of pain are already in use and validated in German language. In contrast, valid, evidence-based and efficient therapeutic options are limited and ask for further clinical studies, ideally randomized controlled trials and meta-analyses.

Investigating the Relationship between the Ratings of Perceived Exertion and Tone-Entropy of Heart Rate Variability during a Graded Exercise

This study explored the autonomic nervous system (ANS) adaptation in relation to exercise and how this correlates with the ratings of perceived exertion (Borg-RPE) over four ranges 6-8; 9-12; 13-16; 17-20, by using the time domain parameters and the multi-lag Tone-Entropy (T-E) of heart rate variability (HRV). ECG signals were collected from ten subjects who were recruited to participate in a graded exercise protocol on a treadmill. Results showed that SDNN and RMSSD decreased from lower to higher Borg-RPE, indicating a decrease in HRV. Entropy significantly decreased along the first 3 Borg-RPE ranges but increased in the recovery phase in which Tone values became negative (high HRV). As Borg-RPE values increased to the 17-20 range, Tone values decreased and Entropy increased compared to the 13-16 interval suggesting vagal predominance as opposed to HRV time domain results. The highest value of Tone was observed in the Borg-RPE 9-12 range indicating paramount sympathetic dominance. The use of multi-lag in T-E 2D space improved the separation of HRV with reference to the Borg-RPE intervals (p<0.05), except between the 13-16 and 17-20 ranges of the Borg-RPE. Results highlighted the analytical power of T-E in assessing both HRV changes and the sympatho-vagal balance throughout a graded exercise. Potentially, T-E analysis can be applied to assess rehabilitation settings and to get further information on ANS modulation at high exercise intensities.

Fatigability during volitional walking in incomplete spinal cord injury: cardiorespiratory and motor performance considerations

Fatigability describes the decline in force production (i.e., performance fatigability) and/or changes in sensations regulating performance (i.e., perceived fatigability) during whole-body activity and poses a major challenge to those living with spinal cord injuries (SCI). After SCI, the inability to overcome disruptions to metabolic homeostasis due to cardiorespiratory limitations and physical deconditioning may contribute to increased fatigability severity. The increased susceptibility to fatigability may have implications for motor control strategies and motor learning. Locomotor training approaches designed to reduce fatigability and enhance aerobic capacity in combination with motor learning may be advantageous for promoting functional recovery after SCI. Future research is required to advance the understanding of the relationship between fatigability, cardiorespiratory function and motor performance following SCI.

Autonomic Nervous System in Paralympic Athletes with Spinal Cord Injury

Individuals sustaining a spinal cord injury (SCI) frequently suffer from sensorimotor and autonomic impairment. Damage to the autonomic nervous system results in cardiovascular, respiratory, bladder, bowel, and sexual dysfunctions, as well as temperature dysregulation. These complications not only impede quality of life, but also affect athletic performance of individuals with SCI. This article summarizes existing evidence on how damage to the spinal cord affects the autonomic nervous system and impacts the performance in athletes with SCI. Also discussed are frequently used performance-enhancing strategies, with a special focus on their legal aspect and implication on the athletes' health.

Effects of Spinal Cord Injury in Heart Rate Variability After Acute and Chronic Exercise: A Systematic Review

Background: Spinal cord injury (SCI) above T6 is followed by a loss of sympathetic supraspinal control of the heart, disturbing the autonomic balance and increasing cardiovascular risk. Heart rate variability (HRV) is a widely used tool for assessing the cardiac autonomic nervous system and positive adaptations after regular exercise in able-bodied subjects. However, adaptations in SCI subjects are not well known. Objectives: To compare HRV between able-bodied and SCI subjects and analyze the effects of chronic and acute exercise on HRV in the SCI group. Methods: We searched MEDLINE, Embase, Web of Science, SciELO, and Google Scholar databases to July 2016. We selected English and Spanish observational or experimental studies reporting HRV after training or acute exercise in SCI patients. We also included studies comparing HRV in SCI individuals with able-bodied subjects. Animal studies and nontraumatic SCI studies were excluded. We screened 279 articles by title and abstract; of these, we fully reviewed 29 articles. Eighteen articles fulfilled criteria for inclusion in this study. Results: SCI individuals showed lower HRV values in the low frequency band compared to able-bodied subjects. Regular exercise improved HRV in SCI subjects, however time and intensity data were lacking. HRV decreases after an acute bout of exercise on SCI subjects, but recovery kinetics are unknown. Conclusion: HRV is affected following SCI. Able-bodied subjects and SCI individuals have different values of HRV. Acute bouts of exercise change HRV temporarily, and chronic exercise might improve autonomic balance in SCI.

Participation in moderate-to-vigorous leisure time physical activity is related to decreased visceral adipose tissue in adults with spinal cord injury

Increased visceral adiposity places individuals with chronic spinal cord injury (SCI) at increased risk of cardiometabolic disease. The purpose of this study was to identify if people with chronic SCI who participate in any moderate- to vigorous-intensity leisure time physical activity (LTPA) have lower visceral adipose tissue (VAT) area compared with those who report none. Participants included 136 adult men (n = 100) and women (n = 36) with chronic (mean (±SD) 15.6 ± 11.3 years post-injury) tetraplegia (n = 66) or paraplegia (n = 70) recruited from a tertiary rehabilitation hospital. VAT area was assessed via whole-body dual-energy X-ray absorptiometry using a Hologic densitometer and the manufacturer's body composition software. Moderate-to-vigorous LTPA was assessed using the Leisure Time Physical Activity Questionnaire for People with SCI (LTPAQ-SCI) or the Physical Activity Recall Assessment for People with SCI (PARA-SCI). Summary scores were dichotomized into any or no participation in moderate-to-vigorous LTPA to best represent the intensity described in current population-specific physical-activity guidelines. Data were analyzed using univariate and multiple regression analyses to identify the determinants of VAT. Overall, the model explained 67% of the variance in VAT area and included time post-injury, age-at-injury, android/gynoid ratio, waist circumference, and moderate-to-vigorous LTPA. Participation in any moderate-to-vigorous LTPA was significantly (95% confidence interval: -34.71 to -2.61, p = 0.02) associated with VAT after controlling for injury-related and body-composition correlates. Moderate-to-vigorous LTPA appears to be related to lower VAT area, suggesting potential for LTPA to reduce cardiometabolic disease risk among individuals with chronic SCI.

Interval training elicits higher enjoyment versus moderate exercise in persons with spinal cord injury

BACKGROUND

High intensity interval training (HIIT) is a robust and time-efficient approach to improve multiple health indices including maximal oxygen uptake (VO2max). Despite the intense nature of HIIT, data in untrained adults report greater enjoyment of HIIT versus continuous exercise (CEX). However, this has yet to be investigated in persons with spinal cord injury (SCI).

OBJECTIVE

To examine differences in enjoyment in response to CEX and HIIT in persons with SCI.

DESIGN

Repeated measures, within-subjects design.

SETTING

University laboratory in San Diego, CA.

PARTICIPANTS

Nine habitually active men and women (age = 33.3 ± 10.5 years) with chronic SCI.

INTERVENTION

Participants performed progressive arm ergometry to volitional exhaustion to determine VO2peak. During subsequent sessions, they completed CEX, sprint interval training (SIT), or HIIT in randomized order.

OUTCOME MEASURES

Physical activity enjoyment (PACES), affect, rating of perceived exertion (RPE), VO2, and blood lactate concentration (BLa) were measured.

RESULTS

Despite a higher VO2, RPE, and BLa consequent with HIIT and SIT (P < 0.05), PACES was significantly higher (P = 0.03) in response to HIIT (107.4 ± 13.4) and SIT (103.7 ± 12.5) compared to CEX (81.6 ± 25.4). Fifty-five percent of participants preferred HIIT and 45% preferred SIT, with none identifying CEX as their preferred exercise mode.

CONCLUSION

Compared to CEX, brief sessions of submaximal or supramaximal interval training elicit higher enjoyment despite higher metabolic strain. The long-term efficacy and feasibility of HIIT in this population should be explored considering that it is not viewed as more aversive than CEX.

Measurement of Physical Activity and Energy Expenditure in Wheelchair Users: Methods, Considerations and Future Directions

Accurately measuring physical activity and energy expenditure in persons with chronic physical disabilities who use wheelchairs is a considerable and ongoing challenge. Quantifying various free-living lifestyle behaviours in this group is at present restricted by our understanding of appropriate measurement tools and analytical techniques. This review provides a detailed evaluation of the currently available measurement tools used to predict physical activity and energy expenditure in persons who use wheelchairs. It also outlines numerous considerations specific to this population and suggests suitable future directions for the field. Of the existing three self-report methods utilised in this population, the 3-day Physical Activity Recall Assessment for People with Spinal Cord Injury (PARA-SCI) telephone interview demonstrates the best reliability and validity. However, the complexity of interview administration and potential for recall bias are notable limitations. Objective measurement tools, which overcome such considerations, have been validated using controlled laboratory protocols. These have consistently demonstrated the arm or wrist as the most suitable anatomical location to wear accelerometers. Yet, more complex data analysis methodologies may be necessary to further improve energy expenditure prediction for more intricate movements or behaviours. Multi-sensor devices that incorporate physiological signals and acceleration have recently been adapted for persons who use wheelchairs. Population specific algorithms offer considerable improvements in energy expenditure prediction accuracy. This review highlights the progress in the field and aims to encourage the wider scientific community to develop innovative solutions to accurately quantify physical activity in this population.

Gait training after spinal cord injury: safety, feasibility and gait function following 8 weeks of training with the exoskeletons from Ekso Bionics

STUDY DESIGN

Prospective quasi-experimental study, pre- and post-design.

OBJECTIVES

Assess safety, feasibility, training characteristics and changes in gait function for persons with spinal cord injury (SCI) using the robotic exoskeletons from Ekso Bionics.

SETTING

Nine European rehabilitation centres.

METHODS

Robotic exoskeleton gait training, three times weekly over 8 weeks. Time upright, time walking and steps in the device (training characteristics) were recorded longitudinally. Gait and neurological function were measured by 10 Metre Walk Test (10 MWT), Timed Up and Go (TUG), Berg Balance Scale (BBS), Walking Index for Spinal Cord Injury (WISCI) II and Lower Extremity Motor Score (LEMS).

RESULTS

Fifty-two participants completed the training protocol. Median age: 35.8 years (IQR 27.5-52.5), men/women: N = 36/16, neurological level of injury: C1-L2 and severity: AIS A-D (American Spinal Injury Association Impairment Scale). Time since injury (TSI) < 1 year, N = 25; > 1 year, N = 27. No serious adverse events occurred. Three participants dropped out following ankle swelling (overuse injury). Four participants sustained a Category II pressure ulcer at contact points with the device but completed the study and skin normalized. Training characteristics increased significantly for all subgroups. The number of participants with TSI < 1 year and gait function increased from 20 to 56% (P = 0.004) and 10MWT, TUG, BBS and LEMS results improved (P < 0.05). The number of participants with TSI > 1 year and gait function, increased from 41 to 44% and TUG and BBS results improved (P < 0.05).

CONCLUSIONS

Exoskeleton training was generally safe and feasible in a heterogeneous sample of persons with SCI. Results indicate potential benefits on gait function and balance.

Fatigability, oxygen uptake kinetics and muscle deoxygenation in incomplete spinal cord injury during treadmill walking

PURPOSE

The purpose of the present study was to characterize hypothesized relationships among fatigability and cardiorespiratory fitness in individuals with chronic motor-incomplete SCI (iSCI) during treadmill walking. The theoretical framework was that exacerbated fatigability would occur concomitantly with diminished cardiorespiratory fitness in people with iSCI.

METHODS

Subjects with iSCI (n = 8) and an able-bodied reference group (REF) (n = 8) completed a 6-min walking bout followed by a walking bout of 30-min or until volitional exhaustion, both at a self-selected walking speed. Fatigability was assessed using both perceived fatigability and performance fatigability measures. Pulmonary oxygen uptake kinetics (VO₂ on-kinetics) was measured breath-by-breath and changes in deoxygenated hemoglobin/myoglobin concentration (∆[HHb]) of the lateral gastrocnemius was measured by near-infrared spectroscopy. Adjustment of VO₂ and ∆[HHb] on-kinetics were modeled using a mono-exponential equation.

RESULTS

Perceived fatigability and performance fatigability were 52% and 44% greater in the iSCI group compared to the REF group (p = 0.003 and p = 0.004). Phase II time constant (τp) of VO₂ on-kinetics and ∆[HHb] ½ time during resting arterial occlusion were 55.4% and 16.3% slower in iSCI vs REF (p < 0.01 and p = 0.047, respectively).

CONCLUSIONS

The results of the present study may suggest that compromised O₂ delivery and/or utilization may have contributed to the severity of fatigability in these individuals with iSCI. The understanding of the extent to which fatigability and VO₂ and Δ[HHb] on-kinetics impacts locomotion after iSCI will assist in the future development of targeted interventions to enhance function.

The intensity and match load comparison between high spinal cord injury and non-spinal cord injury wheelchair basketball players: a case report

INTRODUCTION

This is a comparative case study between one high spinal cord injury (SCI) and two non-SCI players during an official wheelchair basketball (WB) match. The aim of the study was to calculate the differences in the absolute and relative HR responses and in the match load among one SCI and two non-SCI players in the same WB match.

CASE PRESENTATION

The study was conducted with first-division WB players in Vitoria-Gasteiz, Spain (2014). All of the participants had played the whole official WB match. Absolute heart rate (HR) in the test (10 m Yo-Yo Intermittent Recovery Test Level 1, YYIR1 10 m) as well as absolute and relative HR and match load (ML) were recorded for these three players in an official WB match.

DISCUSSION

The HRpeak and mean during the YYIR1 10 m test and the whole WB match were lower for the SCI player than the non-SCI players. However, as opposed to absolute HR values, relative HR values and ML reported very similar responses among SCI and non-SCI values. Moreover, in the high-intensity HR zone the values were similar among the three players but not in the low (<75% of HRpeak), moderate (75-85% of HRpeak) and maximal (>95% of HRpeak) HR zones. Although the absolute HR values were lower for the SCI player, the relative values and the ML were similar for all the players. Therefore, it could be necessary to use relative HR values to quantify the intensity of efforts in the WB matches.

Physiological responses between players with and without spinal cord injury in wheelchair basketball small-sided games

STUDY DESIGN

This is a comparative study between players with and without spinal cord injury (SCI) during a training task.

OBJECTIVE

This study examined physiological responses in commonly used small-sided games (SSGs) in well-experienced wheelchair basketball (WB) players with SCI and without SCI (Non-SCI).

SETTING

The study was conducted with a WB team in Vitoria-Gasteiz, Spain (2014).

METHODS

The team was divided into an SCI group (n=6) and a Non-SCI group (n=6). Absolute and relative heart rate (HR) along with tympanic temperature and perceived exertion (RPE) were recorded for both groups.

RESULTS

The two groups attained different absolute HR values for the same SSG. However, no significant differences were observed in relative HR between groups (%HRmean, %HRpeak and the percentage of the time spent in each HR zone: low, moderate, high and maximal) nor in tympanic temperature. Moreover, in relation to the bout evolution analysis (4 repetitions of 4 min), the Non-SCI group significantly increased (P<0.05) absolute HRmean and HRpeak during bouts, whereas the SCI group maintained them constant. Furthermore, the variations in the percentage of the time spent in each HR zone only were observed in the Non-SCI group.

CONCLUSION

In spite of the Non-SCI group attaining higher absolute HR values, the SCI and Non-SCI groups may have similar HR relative values during a specific WB training task. However, the SCI group reported significantly higher values in respiratory RPE in the last bout than the Non-SCI group for the same SSG.

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.

Predicting peak oxygen uptake from submaximal exercise after spinal cord injury

The purpose of this study was to determine the validity of the 6-min arm ergometry test (6MAT) in predicting peak oxygen consumption (V̇O2peak) in individuals with chronic spinal cord injury (SCI). Fifty-two individuals with chronic SCI (age, 38 ± 10 years; American Spinal Injury Association Impairment Scale (AIS), A-D; neurological level of injury (NLI), C1-L2; years post-injury (YPI), 13 ± 10 years) completed an incremental arm ergometry V̇O2peak test and a submaximal 6MAT. Oxygen consumption (V̇O2) data from both tests were used to create a predictive equation with regression analysis. Subsequently, a cross-validation group comprising an additional 10 individuals with SCI (age, 39 ± 13 years; AIS, A-D; NLI, C3-L3; YPI, 9 ± 9 years) were used to determine the predictive power of the equation. All participants were able to complete both the V̇O2peak and 6MAT assessments. Regression analysis yielded the following equation to predict V̇O2peak from end-stage 6MAT V̇O2: V̇O2peak (mL·kg(-1)·min(-1)) = 1.501(6MAT V̇O2) - 0.940. Correlation between measured and predicted V̇O2peak was excellent (r = 0.89). No significant difference was found between measured (17.41 ± 7.44 mL·kg(-1)·min(-1)) and predicted (17.42 ± 6.61 mL·kg(-1)·min(-1)) V̇O2peak (p = 0.97). When cross-validated with a sample of 10 individuals with SCI, correlation between measured and predicted V̇O2peak remained high (r = 0.89), with no differences between measured (18.81 ± 8.35 mL·kg(-1)·min(-1)) and predicted (18.73 ± 7.27 mL·kg(-1)·min(-1)) V̇O2peak (p = 0.75). Results suggest that 6MAT V̇O2 can be used to predict V̇O2peak among individuals with chronic SCI. The 6MAT should be used as a clinical tool for assessing aerobic capacity when peak exercise testing is not feasible.

The role of autonomic function on sport performance in athletes with spinal cord injury

Devastating paralysis, autonomic dysfunction, and abnormal cardiovascular control present significant hemodynamic challenges to individuals with spinal cord injury (SCI), especially during exercise. In general, resting arterial pressure after SCI is lower than with able-bodied individuals and is commonly associated with persistent orthostatic intolerance along with transient episodes of life-threatening hypertension, known as "autonomic dysreflexia." During exercise, the loss of central and reflexive cardiovascular control attenuates maximal heart rate and impairs blood pressure regulation and blood redistribution, which ultimately reduces venous return, stroke volume, and cardiac output. Thermoregulation also is severely compromised in high-lesion SCI, a problem that is compounded when competing in hot and humid conditions. There is some evidence that enhancing venous return via lower body positive pressure or abdominal binding improves exercise performance, as do cooling strategies. Athletes with SCI also have been documented to self-induce autonomic dysreflexia before competition with a view of increasing blood pressure and improving their performance, a technique known as "boosting." For health safety reasons, boosting is officially banned by the International Paralympics Committee. This article addresses the complex issue of how the autonomic nervous system affects sports performance in athletes with SCI, with a specific focus on the potential debilitating effects of deranged cardiovascular control.

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.

Assessment of the talk test and rating of perceived exertion for exercise intensity prescription in persons with paraplegia

BACKGROUND

Physical activity recommendations require accurate estimations of exercise intensity. Rating of Perceived Exertion (RPE) and talk test (TT) are 2 commonly recommended techniques to gauge intensity. It is not known whether these are valid to select an exercise intensity that would elicit a training effect for persons with spinal cord injury (SCI).

OBJECTIVE

To define the exercise intensity of each TT stage and RPE exercise intensity category and assess whether persons with paraplegia are able to use the TT to select a "comfortable" exercise workload they could maintain for 15 minutes.

METHODS

Twelve participants with paraplegia completed 2 arm crank exercise tests on nonconsecutive days within 14 days. Test 1 was an incremental peak effort assessment. Test 2 was a 15-minute simulated exercise session at a participant-selected fixed workload. During each test, participants reported their RPE and performed a TT at 2-minute intervals.

RESULTS

The intensity of the first negative TT stage was vigorous (75 ± 15 %VO2R); at low and moderate intensities, perceived effort was greater than measured intensity; at vigorous and maximal intensities, perceived effort matched measured intensity. Individuals successfully used the TT to select an exercise workload they could maintain for 15 minutes. RPE, but not exercise intensity, increased during the 15-minute session.

CONCLUSIONS

During arm crank exercise when speaking is not comfortable (ie, first negative TT), persons with paraplegia are exercising at vigorous intensity, which is sufficient to elicit training effects. During incremental peak exercise testing, RPE does not appear to accurately index low-moderate exercise intensities. During the simulated exercise session, RPE appeared to index peripheral fatigue.

Subjective measures of exercise intensity to gauge substrate partitioning in persons with paraplegia

BACKGROUND

The Borg Rating of Perceived Exertion (RPE) Scale and talk test (TT) are commonly recommended for persons to gauge exercise intensity. It is not known whether they are suitable to estimate substrate partitioning between carbohydrate and fat in persons with SCI.

OBJECTIVE

Investigate substrate partitioning/utilization patterns associated with RPE and TT.

METHODS

Twelve participants with chronic paraplegia underwent 2 arm crank exercise tests on nonconsecutive days within 2 weeks. Test 1 was a graded exercise test (GXT) to volitional exhaustion. Test 2 was a 15-minute self-selected steady state (SS) voluntary arm exercise bout simulating a brief, yet typical exercise session.

RESULTS

For the GXT, very light intensity exercise (RPE < 9) and TT stage before last positive were associated with highest contribution of fat oxidation (~35%-50%) to total energy expenditure (TEE). Fat oxidation was low at all stages, with the highest rate (0.13 ± 0.07 g/min) occurring at stage 1 (10 W). Corresponding average RPE was 7 ± 2 and the TT was positive for all participants at this stage. For the SS, fuel partitioning throughout exercise was dominated by carbohydrate oxidation (1.47 ± 0.08 g/min), accounting for almost all (~94%) of TEE with only a minute contribution from fat oxidation (0.02 ± 0.004 g/min). A positive TT was associated with an average contribution of fat oxidation of ~10%.

CONCLUSIONS

RPE but not the TT appears suitable to predict exercise intensities associated with the highest levels of fat oxidation. However, such intensities are below authoritative intensity thresholds for cardiorespiratory fitness promotion, and therefore the applicability of such a prediction for exercise prescriptions is likely limited to individuals with low exercise tolerance.

Physical strain of handcycling: an evaluation using training guidelines for a healthy lifestyle as defined by the American College of Sports Medicine

OBJECTIVE

Developments in assistive technology such as handcycling provide attractive possibilities to pursue a healthy lifestyle for patients with spinal cord injury. The objective of the study is to evaluate physical stress and strain of handcycling against training guidelines as defined by the American College of Sports Medicine (ACSM).

DESIGN

Seven able-bodied males conducted an incremental peak exercise handcycling test on a treadmill. In addition, two indoor treadmill (1.3 m/second with an inclination of 0.7% and 1.0 m/second with an inclination of 4.8%) and three outdoor over ground exercise bouts were performed (1.7, 3.3, and 5.0 m/second). One individual handcycled a representative 8-km-distance outdoors.

OUTCOME MEASURES

Physical stress and strain were described in terms of absolute and relative power output, oxygen uptake (VO2), gross efficiency (GE), and heart rate (HR). Also, local perceived discomfort (LPD) was determined.

RESULTS

Relative handcycling exercise intensities varied between 23.3 ± 4.2 (below the ACSM lower limit of 46%VO2peak) and 72.5 ± 15.1%VO2peak (well above the ACSM lower limit), with GE ranging from 6.0 ± 1.5% at the lower to 13.0 ± 2.6% at the higher exercise intensities. Exercise intensities were performed at 49.8 ± 4.2 to 80.1 ± 10.5%HRpeak. LPD scores were low to moderate (<27 ± 7).

CONCLUSION

Handcycling is relatively efficient and exercise intensities > 46%VO2peak were elicited. However, exercise load seems to be underestimated using %HRpeak. LPD was not perceived as limiting. Physiological stress and strain in able-bodied individuals appear to be comparable to individuals with a paraplegia. To understand individualize and optimize upper-body training, different training programs must be evaluated.

Development of a motor driven rowing machine with automatic functional electrical stimulation controller for individuals with paraplegia; a preliminary study

Objective

To examine the cardiorespiratory responses of patients with spinal cord injury (SCI) paraplegia using a motor driven rowing machine.

Method

Ten SCI patients with paraplegia [A (n=6), B (n=1), and C (n=3) by the American Spinal Injury Association impairment scale] were selected. Two rowing techniques were used. The first used a fixed seat with rowing achieved using only upper extremity movement (fixed rowing). The second used an automatically moving seat, facilitating active upper extremity movement and passive lower extremity movement via the motorized seat (motor rowing). Each patient performed two randomly assigned rowing exercise stress tests 1-3 days apart. The work rate (WR), time, respiratory exchange ratio (R), oxygen consumption (VO₂), heart rate (HR), metabolic equivalents (METs), and rating of perceived exertion (RPE) were recorded.

Results

WR, time, VO₂, and METs were significantly higher after the motor rowing test than after fixed motor rowing test (p<0.05). HR after motor rowing was significantly lower than fixed rowing (p<0.05).

Conclusion

Cardiorespiratory responses as VO₂, HR and METs can be elicited by the motor rowing for people with paraplegic SCI.

Feasibility and effects of patient-cooperative robot-aided gait training applied in a 4-week pilot trial

BACKGROUND

Functional training is becoming the state-of-the-art therapy approach for rehabilitation of individuals after stroke and spinal cord injury. Robot-aided treadmill training reduces personnel effort, especially when treating severely affected patients. Improving rehabilitation robots towards more patient-cooperative behavior may further increase the effects of robot-aided training. This pilot study aims at investigating the feasibility of applying patient-cooperative robot-aided gait rehabilitation to stroke and incomplete spinal cord injury during a therapy period of four weeks. Short-term effects within one training session as well as the effects of the training on walking function are evaluated.

METHODS

Two individuals with chronic incomplete spinal cord injury and two with chronic stroke trained with the Lokomat gait rehabilitation robot which was operated in a new, patient-cooperative mode for a period of four weeks with four training sessions of 45 min per week. At baseline, after two and after four weeks, walking function was assessed with the ten meter walking test. Additionally, muscle activity of the major leg muscles, heart rate and the Borg scale were measured under different walking conditions including a non-cooperative position control mode to investigate the short-term effects of patient-cooperative versus non-cooperative robot-aided gait training.

RESULTS

Patient-cooperative robot-aided gait training was tolerated well by all subjects and performed without difficulties. The subjects trained more actively and with more physiological muscle activity than in a non-cooperative position-control mode. One subject showed a significant and relevant increase of gait speed after the therapy, the three remaining subjects did not show significant changes.

CONCLUSIONS

Patient-cooperative robot-aided gait training is feasible in clinical practice and overcomes the main points of criticism against robot-aided gait training: It enables patients to train in an active, variable and more natural way. The limited number of subjects in this pilot trial does not permit valid conclusions on the effect of patient-cooperative robot-aided gait training on walking function. A large, possibly multi-center randomized controlled clinical trial is required to shed more light on this question.

Submaximal exercise responses in tetraplegic, paraplegic and non spinal cord injured elite wheelchair athletes

It remains unclear whether similar exercise prescription, based on physiological markers, can be applied to subgroups of wheelchair athletes with different disabilities. Therefore, 25 wheelchair athletes, divided into three subgroups [eight tetraplegic (TETRA), nine paraplegic (PARA) and eight non spinal cord injured (NON-SCI)], performed an exercise test consisting of incremental submaximal stages, covering a range from 40% to 80% peak oxygen uptake (%VO(2peak) ). Oxygen uptake (VO(2)), heart rate (HR), blood lactate concentration (BLa) and rating of perceived exertion (RPE) were obtained for each stage. Expressed as a function of BLa, no differences were found between subgroups with respect to %VO(2peak) (group mean ± SD: 1.0 mmol/L: 53.9 ± 9.9%; 2.0 mmol/L: 70.7 ± 7.5%; 3.0 mmol/L: 78.5 ± 7.7%) and RPE [group mean (lower and upper quartile): 1.0 mmol/L: 10.8 (9.9, 12.2); 2.0 mmol/L: 13.6 (12.7, 14.3); 3.0 mmol/L: 14.9 (13.7, 16.5)]. Furthermore, no differences were found in the coefficient of determination (R(2) ) of the HR-VO(2) relationship in any of the subgroups (TETRA: 0.90 ± 0.12; PARA: 0.97 ± 0.02; NON-SCI: 0.96 ± 0.04). These results suggest that exercise prescription using measurements of VO(2), BLa or RPE can be based on the same recommendations in all the subgroups studied. This finding has added value for TETRA athletes, as it offers alternatives to HR monitoring.

Prediction of peak oxygen consumption from the ratings of perceived exertion during a graded exercise test and ramp exercise test in able-bodied participants and paraplegic persons

OBJECTIVE

To assess the accuracy of predicting peak oxygen consumption (Vo(2)peak) from a graded exercise test (GXT) and a ramp exercise test during arm exercise in able-bodied persons and persons with paraplegia using ratings of perceived exertion (RPEs).

DESIGN

Each participant performed a GXT (started at 30W and increased by 15W every 2min) and a ramp exercise test (started at 0W and increased by 15W·min(-1)).

SETTING

Universities' laboratories.

PARTICIPANTS

Able-bodied men (n=13; mean ± SD, 27.2±4.3y) and men with paraplegia (n=12; 31.1±5.7y). Six of the persons with paraplegia had flaccid paralysis as a result of poliomyelitis infection. The other 6 persons had complete spinal cord injuries with neurologic levels at and below T6.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Prediction of Vo(2)peak by extrapolating submaximal oxygen consumption (Vo(2)) and RPE values to RPE 20 on the Borg 6 to 20 RPE scale.

RESULTS

This study showed a very strong linear relationship between RPE and Vo(2) during the GXT and the ramp test for able-bodied persons (R(2)≥.95 and R(2)≥.96, respectively) and persons with paraplegia (R(2)≥.96 and R(2)≥.95, respectively). There was no significant difference between measured and predicted Vo(2)peak from RPEs before and including RPE 13, 15, and 17 during the GXT for persons with paraplegia (P>.05). For the able-bodied participants, there was no significant difference between measured and predicted Vo(2)peak from RPEs before and including RPE 15 and 17 during the ramp exercise test (P>.05).

CONCLUSION

The GXT provided acceptable predictions of Vo(2)peak for persons with paraplegia, and the ramp test provided acceptable predictions of Vo(2)peak for able-bodied persons.

Muscle activity and time to task failure differ with load compliance and target force for elbow flexor muscles

The primary purpose of this study was to determine the influence of load compliance on time to failure during sustained isometric contractions performed with the elbow flexor muscles at four submaximal target forces. Subjects pulled against a rigid restraint during the force task and maintained a constant elbow angle, while supporting an equivalent inertial load during the position task. Each task was sustained for as long as possible. Twenty-one healthy adults (23 ± 6 yr; 11 men) participated in the study. The maximal voluntary contraction (MVC) force was similar (P = 0.95) before the subjects performed the force and position tasks at each of the four target forces: 20, 30, 45, and 60% of MVC force. The time to task failure was longer for the force tasks (576 ± 80 and 325 ± 70 s) than for the position tasks (299 ± 77 and 168 ± 35 s) at target forces of 20 and 30% (P < 0.001), but was similar for the force tasks (178 ± 35 and 86 ± 14 s) and the position tasks (132 ± 29 and 87 ± 14 s) at target forces of 45 and 60% (P > 0.19). The briefer times to failure for the position task at the lower forces were accompanied by greater rates of increase in elbow flexor muscle activity, mean arterial pressure, heart rate, and rating of perceived exertion. There was no difference in the estimates of external mechanical work at any target force. The dominant mechanisms limiting time to failure of sustained isometric contractions with the elbow flexor muscles appear to change at target forces between 30 and 45% MVC, with load compliance being a significant factor at lower forces only.

Prediction of peak oxygen uptake from ratings of perceived exertion during arm exercise in able-bodied and persons with poliomyelitis

STUDY DESIGN

Each participant completed an arm-crank ramp exercise test to volitional exhaustion.

OBJECTIVE

To assess the utility of the rating of perceived exertion (RPE) to predict peak oxygen uptake (VO(2)peak) during arm ergometry in able-bodied participants and those with poliomyelitis.

SETTING

University of Jordan, Amman, Jordan.

PARTICIPANTS

In all, 16 able-bodied and 15 participants with poliomyelitis completed an arm-crank ramp exercise test to volitional exhaustion.

MAIN OUTCOME MEASURES

The prediction of VO(2)peak is calculated by extrapolating the sub-maximal RPE and VO(2) values by linear regression to RPE 20.

RESULTS

For the able-bodied participants, there were no significant differences between measured and predicted VO(2)peak from the three sub-maximal ranges of the RPE (RPEs before and including RPE 13, 15 and 17, P > 0.05). For the participants with poliomyelitis, the VO(2)peak predicted from RPEs before and including RPE 13 was significantly higher than measured VO(2)max (P < 0.05). The 95% limits of agreement of able-bodied participants for RPE 13, 15 and 17 (-3 ± 14, -1 ± 10 & 0 ± 8 ml kg(-1) min(-1), respectively) were lower than those observed for poliomyelitis participants (6 ± 19, 2 ± 12 and 1 ± 9 ml kg(-1) min(-1), respectively).

CONCLUSION

This study has shown that the estimation of VO(2)peak from submaximal RPE during arm ergometry is generally more accurate in able-bodied participants in comparison with those with poliomyelitis.