Effect of abdominal binding on respiratory mechanics during exercise in athletes with cervical spinal cord injury

Toward a Standardized and Individualized Laboratory-Based Protocol for Wheelchair-Specific Exercise Capacity Testing in Wheelchair Athletes: A Scoping Review

ABSTRACT

Previous studies on handrim wheelchair-specific (an)aerobic exercise capacity in wheelchair athletes have used a diversity of participants, equipment, and protocols. Therefore, test results are difficult to compare among studies. The first aim of this scoping review is to provide an overview of the populations studied, the equipment and protocols used, and the reported outcomes from all laboratory-based studies on wheelchair-specific exercise capacity in wheelchair athletes. The second aim is to synthesize these findings into a standardized, yet individualized protocol. A scoping literature search resulted in 10 anaerobic and 38 aerobic protocols. A large variety in equipment, protocol design, and reported outcomes was found. Studies that systematically investigated the influence of protocol features are lacking, which makes it difficult to interpret and compare test outcomes among the heterogeneous group of wheelchair athletes. Protocol design was often dependent on a priori participant knowledge. However, specific guidelines for individualization were missing. However, the common protocol features of the different studies were united into guidelines that could be followed when performing standardized and individualized wheelchair-specific exercise capacity tests in wheelchair athletes. Together with guidelines regarding reporting of participant characteristics, used equipment, and outcome measures, we hope to work toward more international agreement in future testing.

Defining Training and Performance Caliber: A Participant Classification Framework

Throughout the sport-science and sports-medicine literature, the term "elite" subjects might be one of the most overused and ill-defined terms. Currently, there is no common perspective or terminology to characterize the caliber and training status of an individual or cohort. This paper presents a 6-tiered Participant Classification Framework whereby all individuals across a spectrum of exercise backgrounds and athletic abilities can be classified. The Participant Classification Framework uses training volume and performance metrics to classify a participant to one of the following: Tier 0: Sedentary; Tier 1: Recreationally Active; Tier 2: Trained/Developmental; Tier 3: Highly Trained/National Level; Tier 4: Elite/International Level; or Tier 5: World Class. We suggest the Participant Classification Framework can be used to classify participants both prospectively (as part of study participant recruitment) and retrospectively (during systematic reviews and/or meta-analyses). Discussion around how the Participant Classification Framework can be tailored toward different sports, athletes, and/or events has occurred, and sport-specific examples provided. Additional nuances such as depth of sport participation, nationality differences, and gender parity within a sport are all discussed. Finally, chronological age with reference to the junior and masters athlete, as well as the Paralympic athlete, and their inclusion within the Participant Classification Framework has also been considered. It is our intention that this framework be widely implemented to systematically classify participants in research featuring exercise, sport, performance, health, and/or fitness outcomes going forward, providing the much-needed uniformity to classification practices.

Effects of trunk muscle activation on trunk stability, arm power, blood pressure and performance in wheelchair rugby players with a spinal cord injury

Objective: In wheelchair rugby (WR) athletes with tetraplegia, wheelchair performance may be impaired due to (partial) loss of innervation of upper extremity and trunk muscles, and low blood pressure (BP). The objective was to assess the effects of electrical stimulation (ES)-induced co-contraction of trunk muscles on trunk stability, arm force/power, BP, and WR performance.Design: Cross-sectional study.Setting: Rehabilitation research laboratory and WR court.Participants: Eleven WR athletes with tetraplegia.Interventions: ES was applied to the rectus abdominis, obliquus externus abdominis and erector spinae muscles. For every test, the ES condition was compared to the non-ES condition.Outcome measures: Stability was assessed with reaching tasks, arm force/power with an isokinetic test on a dynamometer, BP during an ES protocol and WR skill performance with the USA Wheelchair Rugby Skill Assessment.Results: Overall reaching distance (ES 14.6 ± 7.5 cm, non-ES 13.4 ± 8.2 cm), and BP showed a significant increase with ES. Arm force (ES 154 ± 106 N, non-ES 148 ± 102 N) and power (ES 37 ± 26 W, non-ES 36 ± 25 W), and WR skills were not significantly improved.Conclusion: ES-induced trunk muscle activation positively affects trunk stability and BP, but not arm force/power. No effects were found in WR skill performance, probably due to abdominal strapping. More research is needed to assess different ES (training) protocols and longitudinal effects.

Influence of respiratory loading on left-ventricular function in cervical spinal cord injury

KEY POINTS

Cervical spinal cord injury (C-SCI) alters both the cardiac and respiratory systems, however little is known as to how these systems interact following injury. Here, we manipulated inspiratory or expiratory intrathoracic pressure (ITP) to mechanistically test the role of the respiratory pump on circulatory function in highly-trained individuals with C-SCI and an able-bodied reference group. In individuals with C-SCI, greater ITP during expiratory loading caused dynamic hyperinflation that was associated with impaired left-ventricular filling. More negative ITP during inspiratory loading did not significantly alter left-ventricular volumes in either group. Interventions that prevent dynamic hyperinflation and/or enhance the ability to generate expiratory pressures may help preserve left-ventricular filling in individuals with C-SCI.

ABSTRACT

Cervical spinal cord injury (C-SCI) negatively impacts cardiac and respiratory function. As the heart and lungs are linked via the pulmonary circuit these systems are interdependent. Here, we utilized inspiratory and expiratory loading to assess whether augmenting the respiratory pump improves left-ventricular (LV) filling and output in individuals with motor-complete C-SCI. We hypothesized LV end-diastolic volume (LVEDV) would increase and decrease with inspiratory and expiratory loading, respectively. Participants (C-SCI: 7M/1F, 35±7 years; able-bodied: 7M/1F, 32±6 years) were assessed under five conditions during 45° head-up tilt; unloaded, inspiratory loading with -10 and -20cmH₂ O esophageal pressure (Pes) on inspiration, and expiratory loading with +10 and +20cmH₂ O Pes on expiration. An esophageal balloon catheter monitored Pes and LV structure and function were assessed by echocardiography. In C-SCI only, (1) +20cmH₂ O reduced LVEDV vs. unloaded (81±15 vs. 88±11 mL, p = 0.006); (2) heart rate was higher during +20cmH₂ O compared to unloaded (p = 0.001) and +10cmH₂ O (p = 0.002); (3) cardiac output was higher during +20cmH₂ O than unloaded (p = 0.002); and (4) end-expiratory lung volume was higher during +20cmH₂ O vs. unloaded (63±10 vs. 55±13% total lung capacity, p = 0.003) but was unaffected by inspiratory loading. In both groups, -10 and -20cmH₂ O had no significant effect on LVEDV. These findings suggest greater expiratory positive pressure acutely impairs LV filling in C-SCI, potentially via impaired venous return, mediastinal constraint and/or direct ventricular interaction subsequent to dynamic hyperinflation. Inspiratory loading did not significantly improve LV function in C-SCI and neither inspiratory nor expiratory loading affected cardiac function or lung volumes in able-bodied participants. Abstract figure legend Background: Cervical spinal cord injury (C-SCI) alters both the cardiac and respiratory systems. However, expiratory function is compromised to a greater extent than inspiratory function. Experimental set up: To examine how the cardiac and respiratory systems interact following C-SCI we manipulated inspiratory or expiratory intrathoracic pressure (ITP) to mechanistically test how changes in ITP and lung volumes influence cardiac function in highly-trained individuals with C-SCI and an able-bodied reference group. Participants were assessed under five conditions during 45° head-up tilt; unloaded, two inspiratory loading, and two expiratory loading conditions.

KEY FINDINGS

Following C-SCI, greater ITP during expiratory loading increased lung volumes and was associated with impaired left-ventricular filling. Interventions that prevent increases in lung volumes and/or enhance the ability to generate expiratory pressures may help preserve left-ventricular filling in individuals with C-SCI. A portion of this figure was created with biorender.com This article is protected by copyright. All rights reserved.

Physiological Considerations to Support Podium Performance in Para-Athletes

The twenty-first century has seen an increase in para-sport participation and the number of research publications on para-sport and the para-athlete. Unfortunately, the majority of publications are case reports/case series or study single impairment types in isolation. Indeed, an overview of how each International Paralympic Committee classifiable impairment type impact athlete physiology, health, and performance has not been forthcoming in the literature. This can make it challenging for practitioners to appropriately support para-athletes and implement evidence-based research in their daily practice. Moreover, the lack of a cohesive publication that reviews all classifiable impairment types through a physiological lens can make it challenging for researchers new to the field to gain an understanding of unique physiological challenges facing para-athletes and to appreciate the nuances of how various impairment types differentially impact para-athlete physiology. As such, the purpose of this review is to (1) summarize how International Paralympic Committee classifiable impairments alter the normal physiological responses to exercise; (2) provide an overview of "quick win" physiological interventions targeted toward specific para-athlete populations; (3) discuss unique practical considerations for the para-sport practitioner; (4) discuss research gaps and highlight areas for future research and innovation, and (5) provide suggestions for knowledge translation and knowledge sharing strategies to advance the field of para-sport research and its application by para-sport practitioners.

How does cervical spinal cord injury impact the cardiopulmonary response to exercise?

We compared cardiopulmonary responses to arm-ergometry in individuals with cervical spinal cord injury (C-SCI) and able-bodied controls. We hypothesized that individuals with C-SCI would have higher respiratory frequency (f_b) but lower tidal volume (VT) at a given work rate and dynamically hyperinflate during exercise, whereas able-bodied individuals would not. Participants completed pulmonary function testing, an arm-ergometry test to exhaustion, and a sub-maximal exercise test consisting of four-minute stages at 20, 40, 60, and 80% peak work rate. Able-bodied individuals completed a further sub-maximal test with absolute work rate matched to C-SCI. During work rate matched sub-maximal exercise, C-SCI had smaller VT (main effect p < 0.001) compensated by an increased f_b (main effect p = 0.009). C-SCI had increased end-expiratory lung volume at 80% peak work rate vs. rest (p < 0.003), whereas able-bodied did not. In conclusion, during arm-ergometry, individuals with C-SCI exhibit altered ventilatory patterns characterized by reduced VT, higher f_b, and dynamic hyperinflation that may contribute to the observed reduced aerobic exercise capacity.

Criterion Validity of a Field-Based Assessment of Aerobic Capacity in Wheelchair Rugby Athletes

PURPOSE

To confirm whether peak aerobic capacity determined during laboratory testing could be replicated during an on-court field-based test in wheelchair rugby players.

METHODS

Sixteen wheelchair rugby players performed an incremental speed-based peak oxygen uptake (V˙O2peak) test on a motorized treadmill (TM) and completed a multistage fitness test (MFT) on a basketball court in a counterbalanced order, while spirometric data were recorded. A paired t test was performed to check for systematic error between tests. A Bland-Altman plot for V˙O2peak illustrated the agreement between the TM and MFT results and how this related to the boundaries of practical equivalence.

RESULTS

No significant differences between mean V˙O2peak were reported (TM: 1.85 [0.63] vs MFT: 1.81 [0.63] L·min-1; P = .33). Bland-Altman plot for V˙O2peak suggests that the mean values are in good agreement at the group level; that is, the exact 95% confidence limits for the ratio systematic error (0.95-1.02) are within the boundaries of practical equivalence (0.88-1.13) showing that the group average TM and MFT values are interchangeable. However, consideration of the data at the level of the individual athlete suggests that the TM and MFT results were not interchangeable because the 95% ratio limits of agreement either coincide with the boundaries of practical equivalence (upper limit) or fall outside (lower limit).

CONCLUSIONS

Results suggest that the MFT provides a suitable test at a group level with this cohort of wheelchair rugby players for the assessment of V˙O2peak (range 0.97-3.64 L·min-1), yet caution is noted for interchangeable use of values between tests for individual players.

Acute Ventilatory Support During Whole-Body Hybrid Rowing in Patients With High-Level Spinal Cord Injury: A Randomized Controlled Crossover Trial

BACKGROUND

High-level spinal cord injury (SCI) results in profound spinal and supraspinal deficits, leading to substantial ventilatory limitations during whole-body hybrid functional electrical stimulation (FES)-rowing, a form of exercise that markedly increases the active muscle mass via electrically induced leg contractions. This study tested the effect of noninvasive ventilation (NIV) on ventilatory and aerobic capacities in SCI.

METHODS

This blinded, randomized crossover study enrolled 19 patients with SCI (level of injury ranging from C4 to T8). All patients were familiar with FES-rowing and had plateaued in their training-related increases in aerobic capacity. Patients performed two FES-rowing peak exercise tests with NIV or without NIV (sham).

RESULTS

NIV increased exercise tidal volume (peak, 1.50 ± 0.31 L vs 1.36 ± 0.34 L; P < .05) and reduced breathing frequency (peak, 35 ± 7 beats/min vs 38 ± 6 beats/min; P < .05) compared with the sham test, leading to no change in alveolar ventilation but a trend toward increased oxygen uptake efficiency (P = .06). In those who reached peak oxygen consumption (Vo₂peak) criteria (n = 13), NIV failed to significantly increase Vo₂peak (1.73 ± 0.66 L/min vs 1.78 ± 0.59 L/min); however, the range of responses revealed a correlation between changes in peak alveolar ventilation and Vo₂peak (r = 0.89; P < .05). Furthermore, those with higher level injuries and shorter time since injury exhibited the greatest increases in Vo₂peak.

CONCLUSIONS

Acute NIV can successfully improve ventilatory efficiency during FES exercise in SCI but may not improve Vo₂peak in all patients. Those who benefit most seem to be patients with cervical SCI within a shorter time since injury.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT02865343 and NCT03267212; URL: www.clinicaltrials.gov.

Perceived exertion responses to wheelchair propulsion differ between novice able-bodied and trained wheelchair sportspeople

OBJECTIVES

To investigate peripheral (RPE_P) and central (RPE_C) Ratings of Perceived Exertion during wheelchair propulsion in untrained able-bodied (AB) participants, and trained wheelchair rugby athletes with and without cervical spinal cord injury (CSCI).

DESIGN

Cross-sectional study.

METHODS

38 participants (AB: n=20; wheelchair rugby athletes with CSCI: n=9; without CSCI: n=9) completed an incremental wheelchair propulsion test to exhaustion on a motorised treadmill. Gas exchange measures and heart rate (HR) were collected throughout. RPE_P and RPE_C on the Category Ratio-10 were verbally recorded each minute. Blood lactate concentration ([BLa]) was determined post-test.

RESULTS

Between 50-100% peak oxygen uptake (V̇O_2peak), RPE_P was greater than RPE_C in AB (p<0.05), but not in athletes with (p=0.07) or without (p=0.16) CSCI. RPE_P was greater in AB compared to players with CSCI (Effect sizes: 1.24-1.62), as were respiratory exchange ratio (1.02±0.10 vs 0.82±0.11, p<0.05) and [BLa]_peak (7.98±2.53 vs 4.66±1.57mmol·L^-1). RPE_C was greater in athletes without CSCI compared to those with CSCI (Effect sizes: 0.70-1.38), as were HR (166±20 vs 104±15 beats·min^-1, p<0.05) and ventilation (59.2±28.8 vs 35.1±16.6L·min^-1, p=0.01).

CONCLUSIONS

RPE_P was dominant over RPE_C during wheelchair propulsion for untrained AB participants. For athletes with CSCI, lower RPE_P and RPE_C were reported at the same %V̇O_2peak compared to those without CSCI. The mechanism for this remains to be fully elucidated.

Study of abdominal wall muscle innervation applied to large-defect closure in congenital diaphragmatic hernia

In large congenital diaphragmatic hernias (CDHs), direct suture of the diaphragm is impossible. Surgeons can use a triangular internal oblique muscle (IOM) plus transverse abdominis muscle (TAM) flap. Its caudal limit faces the medial extremity of the 11th rib. Clinical studies show that the flap is not hypotonic but that the procedure could expose patients already presenting a hypoplastic lung to external oblique muscle (EOM) hypotonia. The aims of this study were to study EOM innervation by the 10th intercostal nerve (ICN) and ICN innervation to the IOM and TAM. Forty cadaveric abdominal hemi-walls were dissected. The number of branches and the trajectory of each specimen's 10th ICN were studied medially to the medial extremity of the 11th rib (MEK11) using surgical goggles and a microscope (Carl Zeiss®). The 10th ICN was consistently found between the IOM and TAM. There was a median of nine branches from the 10th ICN to the EOM, 77% of them medial to the MEK11. Median values of nine and 12 branches for the IOM and TAM were found, 60% and 51%, respectively, medial to the MEK11. These results argue in favor of good innervation to the IOM plus TAM flap but also indicate postoperative abdominal weakness exposing patients to herniation risks, as more than 75% of the branches from the 10th ICN to the EOM were sectioned or pulled away during flap detachment. Clin. Anat., 33:759-766, 2020. © 2019 Wiley Periodicals, Inc.

Comparison of abdominal compression devices in persons with abdominal paralysis due to spinal cord injury

Study Design

Single subject design with five subjects.

Objectives

The objetive of this study is to compare the effectiveness and usability of alternative commercial abdominal compression garments with participants' usual medical binders.

Setting

Private residences in Pierce and King Counties, WA, USA.

Methods

Participants wore each garment for 5 days followed by a 2-day washout in personal binder. Week 1: Personal binder. Weeks 2 and 3: Randomly ordered test garments (tank, bodysuit). Physiologic measurements: blood pressure (SBP, DBP), blood oxygen saturation (SaO2), forced expiratory volume in one second (FEV1), and heart rate (HR). Participants completed logs twice daily for 5 days per garment regarding ease of use, comfort, respiration, and appearance. We certify that all applicable institutional and governmental regulations concerning the ethical use of human volunteers were followed during the course of this research.

Results

The use of a personal binder results in significant increases in SBP and FEV1. Personal binders support FEV1 significantly better than test garments. There is no difference in SBP between test garments and personal binders. There are no significant differences between DBP, SaO2, or HR between participants' personal binders and no binder. Participants reported that neither tank nor bodysuit felt adequately supportive or easy to use.

Conclusions

Abdominal compression improves respiratory function and supports SBP in individuals with chronic SCI. Further research is needed to guide the development of an easy-to-use and physiologically supportive abdominal compression garment.

Mechanical-ventilatory responses to peak and ventilation-matched upper- versus lower-body exercise in normal subjects

New Findings

What is the central question of this study?

To what extent are the mechanical‐ventilatory responses to upper‐body exercise influenced by task‐specific locomotor mechanics?

What is the main finding and its importance?

When compared with lower‐body exercise performed at similar ventilations, upper‐body exercise was characterized by tidal volume constraint, dynamic lung hyperinflation and an increased propensity towards neuromechanical uncoupling of the respiratory system. Importantly, these responses were independent of respiratory dysfunction and flow limitation. Thus, the mechanical ventilatory responses to upper‐body exercise are attributable, in part, to task‐specific locomotor mechanics (i.e. non‐respiratory loading of the thorax).

Abstract

The aim of this study was to determine the extent to which the mechanical ventilatory responses to upper‐body exercise are influenced by task‐specific locomotor mechanics. Eight healthy men (mean ± SD: age, 24 ± 5 years; mass, 74 ± 11 kg; and stature, 1.79 ± 0.07 m) completed two maximal exercise tests, on separate days, comprising 4 min stepwise increments of 15 W during upper‐body exercise (arm‐cranking) or 30 W during lower‐body exercise (leg‐cycling). The tests were repeated at work rates calculated to elicit 20, 40, 60, 80 and 100% of the peak ventilation achieved during arm‐cranking (V˙E, UBE ). Exercise measures included pulmonary ventilation and gas exchange, oesophageal pressure‐derived indices of respiratory mechanics, operating lung volumes and expiratory flow limitation. Subjects exhibited normal resting pulmonary function. Arm‐crank exercise elicited significantly lower peak values for work rate, O₂ uptake, CO₂ output, minute ventilation and tidal volume (p < 0.05). At matched ventilations, arm‐crank exercise restricted tidal volume expansion relative to leg‐cycling exercise at 60% V˙E, UBE (1.74 ± 0.61 versus 2.27 ± 0.68 l, p < 0.001), 80% V˙E, UBE (2.07 ± 0.70 versus 2.52 ± 0.67 l, p < 0.001) and 100% V˙E, UBE (1.97 ± 0.85 versus 2.55 ± 0.72 l, p = 0.002). Despite minimal evidence of expiratory flow limitation, expiratory reserve volume was significantly higher during arm‐cranking versus leg‐cycling exercise at 100% V˙E, UBE (39 ± 8 versus 29 ± 8% of vital capacity, p = 0.002). At any given ventilation, arm‐cranking elicited greater inspiratory effort (oesophageal pressure) relative to thoracic displacement (tidal volume). Arm‐cranking exercise is sufficient to provoke respiratory mechanical derangements (restricted tidal volume expansion, dynamic hyperinflation and neuromechanical uncoupling) in subjects with normal pulmonary function and expiratory flow reserve. These responses are likely to be attributable to task‐specific locomotor mechanics (i.e. non‐respiratory loading of the thorax).

Effect of Abdominal Binding on Diaphragmatic Neuromuscular Efficiency, Exertional Breathlessness, and Exercise Endurance in Chronic Obstructive Pulmonary Disease

We tested the hypothesis that abdominal binding (AB) would reduce breathlessness and improve exercise tolerance by enhancing neuromuscular efficiency of the diaphragm during exercise in adults with chronic obstructive pulmonary disease (COPD). In a randomized, controlled, crossover trial, 20 adults with COPD (mean ± SD FEV₁, 60 ± 16% predicted) completed a symptom-limited constant-load cycle endurance exercise test at 75% of their peak incremental power output with concomitant measures of the diaphragm electromyogram (EMGdi) and respiratory pressures without (CTRL) vs. with AB sufficient to increase end-expiratory gastric pressure (Pga,ee) by 6.7 ± 0.3 cmH₂O at rest. Compared to CTRL, AB enhanced diaphragmatic neuromuscular efficiency during exercise (p < 0.05), as evidenced by a 25% increase in the quotient of EMGdi to tidal transdiaphragmatic pressure swing. By contrast, AB had no demonstrable effect on exertional breathlessness and exercise tolerance; spirometry and plethysmography-derived pulmonary function test parameters at rest; and cardiac, metabolic, breathing pattern, inspiratory reserve volume and EMGdi responses during exercise (all p > 0.05 vs. CTRL). In conclusion, enhanced neuromuscular efficiency of the diaphragm during exercise with AB was not associated with relief of exertional breathlessness and improved exercise tolerance in adults with COPD. Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT01852006.

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.

Peak oxygen uptake in Paralympic sitting sports: A systematic literature review, meta- and pooled-data analysis

Background

Peak oxygen uptake (VO_2peak) in Paralympic sitting sports athletes represents their maximal ability to deliver energy aerobically in an upper-body mode, with values being influenced by sex, disability-related physiological limitations, sport-specific demands, training status and how they are tested.

Objectives

To identify VO_2peak values in Paralympic sitting sports, examine between-sports differences and within-sports variations in VO_2peak and determine the influence of sex, age, body-mass, disability and test-mode on VO_2peak.

Design

Systematic literature review and meta-analysis.

Data sources

PubMed, CINAHL, SPORTDiscus^TM and EMBASE were systematically searched in October 2016 using relevant medical subject headings, keywords and a Boolean.

Eligibility criteria

Studies that assessed VO_2peak values in sitting sports athletes with a disability in a laboratory setting were included.

Data synthesis

Data was extracted and pooled in the different sports disciplines, weighted by the Dersimonian and Laird random effects approach. Quality of the included studies was assessed with a modified version of the Downs and Black checklist by two independent reviewers. Meta-regression and pooled-data multiple regression analyses were performed to assess the influence of sex, age, body-mass, disability, test mode and study quality on VO_2peak.

Results

Of 6542 retrieved articles, 57 studies reporting VO_2peak values in 14 different sitting sports were included in this review. VO_2peak values from 771 athletes were used in the data analysis, of which 30% participated in wheelchair basketball, 27% in wheelchair racing, 15% in wheelchair rugby and the remaining 28% in the 11 other disciplines. Fifty-six percent of the athletes had a spinal cord injury and 87% were men. Sports-discipline-averaged VO_2peak values ranged from 2.9 L∙min^-1 and 45.6 mL∙kg^-1∙min^-1 in Nordic sit skiing to 1.4 L∙min^-1 and 17.3 mL∙kg^-1∙min^-1 in shooting and 1.3 L∙min^-1 and 18.9 mL∙kg^-1∙min^-1 in wheelchair rugby. Large within-sports variation was found in sports with few included studies and corresponding low sample sizes. The meta-regression and pooled-data multiple regression analyses showed that being a man, having an amputation, not being tetraplegic, testing in a wheelchair ergometer and treadmill mode, were found to be favorable for high absolute and body-mass normalized VO_2peak values. Furthermore, high body mass was favourable for high absolute VO_2peak values and low body mass for high body-mass normalized VO_2peak values.

Conclusion

The highest VO_2peak values were found in Nordic sit skiing, an endurance sport with continuously high physical efforts, and the lowest values in shooting, a sport with low levels of displacement, and in wheelchair rugby where mainly athletes with tetraplegia compete. However, VO_2peak values need to be interpreted carefully in sports-disciplines with few included studies and large within-sports variation. Future studies should include detailed information on training status, sex, age, test mode, as well as the type and extent of disability in order to more precisely evaluate the effect of these factors on VO_2peak.

Experimental Protocol of a Three-minute, All-out Arm Crank Exercise Test in Spinal-cord Injured and Able-bodied Individuals

Reliable exercise protocols are required to test changes in exercise performance in elite athletes. Performance improvements in these athletes may be small; therefore, sensitive tools are fundamental to exercise physiology. There are currently many exercise tests that allow for the examination of exercise capacity in able-bodied athletes, with protocols mainly for lower-body or whole-body exercise. There is a trend to test athletes in a sport-specific setting that closely resembles the actions that the participants are used to performing. Only a few protocols test short-term, high-intensity exercise capacity in participants with an impairment of the lower body. Most of these protocols are very sport-specific and are not applicable to a wide range of athletes. One well-known test protocol is the 30 s Wingate test, which is well-established in cycling and in arm crank exercise testing. This test analyzes high-intensity exercise performance over a 30 s time duration. In order to monitor exercise performance over a longer duration, a different method was modified for application to the upper body. The 3 min, all-out arm crank ergometer test allows athletes to be tested in a manner specific to 1,500 m wheelchair racing (in terms of exercise duration), as well as to upper body exercises such as rowing or hand-cycling. In order to increase the reliability with identical test conditions, it is crucial to precisely replicate settings such as the resistance (i.e., torque factor) and the position of the participants (i.e., the height of the crank, the distance between the crank and the participant, and the fixation of the participant). Another important issue concerns the beginning of the exercise test. Fixed revolutions per minute are required to standardize the test conditions for the start of the exercise test. This exercise protocol shows the importance of accurate operations to reproduce identical test conditions and settings.

Abdominal Binding Improves Neuromuscular Efficiency of the Human Diaphragm during Exercise

We tested the hypothesis that elastic binding of the abdomen (AB) would enhance neuromuscular efficiency of the human diaphragm during exercise. Twelve healthy non-obese men aged 24.8 ± 1.7 years (mean ± SE) completed a symptom-limited constant-load cycle endurance exercise test at 85% of their peak incremental power output with diaphragmatic electromyography (EMGdi) and respiratory pressure measurements under two randomly assigned conditions: unbound control (CTRL) and AB sufficient to increase end-expiratory gastric pressure (Pga,ee) by 5-8 cmH₂O at rest. By design, AB increased Pga,ee by 6.6 ± 0.6 cmH₂O at rest. Compared to CTRL, AB significantly increased the transdiaphragmatic pressure swing-to-EMGdi ratio by 85-95% during exercise, reflecting enhanced neuromuscular efficiency of the diaphragm. By contrast, AB had no effect on spirometric parameters at rest, exercise endurance time or an effect on cardiac, metabolic, ventilatory, breathing pattern, dynamic operating lung volume, and perceptual responses during exercise. In conclusion, AB was associated with isolated and acute improvements in neuromuscular efficiency of the diaphragm during exercise in healthy men. The implications of our results are that AB may be an effective means of enhancing neuromuscular efficiency of the diaphragm in clinical populations with diaphragmatic weakness/dysfunction.

Assessing kinematics and kinetics of functional electrical stimulation rowing

Hybrid functional electrical stimulation (FES) rowing has positive effects on cardiovascular fitness, producing significantly greater aerobic power than either upper body or FES exercise alone. However, there is minimal information on the kinematics, kinetics, and mechanical efficiency of FES-rowing in the spinal cord injured (SCI) population. This study examined the biomechanics of FES-rowing to determine how motions, forces, and aerobic demand change with increasing intensity. Six individuals with SCI and six able-bodied subjects performed a progressive aerobic capacity rowing test. Differences in kinematics (motion profiles), kinetics (forces produced by the feet and arms), external mechanical work, and mechanical efficiency (work produced/volume of oxygen consumed) were compared in able-bodied rowing vs. SCI FES-rowing at three comparable subpeak workloads. With increasing exercise intensity (measured as wattage), able-bodied rowing increased stroke rate by decreasing recovery time, while FES-rowing maintained a constant stroke rate, with no change in drive or recovery times. While able-bodied rowers increased leg and arm forces with increasing intensity, FES-rowers used only their arms to achieve a higher intensity with a constant and relatively low contribution of the legs. Oxygen consumption increased in both groups, but more so in able-bodied rowers, resulting in able-bodied rowers having twice the mechanical efficiency of FES-rowers. Our results suggest that despite its ability to allow for whole body exercise, the total force output achievable with FES-rowing results in only modest loading of the legs that affects overall rowing performance and that may limit forces applied to bone.

Action of the diaphragm on the rib cage

When the diaphragm contracts, pleural pressure falls, exerting a caudal and inward force on the entire rib cage. However, the diaphragm also exerts forces in the cranial and outward direction on the lower ribs. One of these forces, the "insertional force," is applied by the muscle at its attachments to the lower ribs. The second, the "appositional force," is due to the transmission of abdominal pressure to the lower rib cage in the zone of apposition. In the control condition at functional residual capacity, the effects of these two forces on the lower ribs are nearly equal and outweigh the effect of pleural pressure, whereas for the upper ribs, the effect of pleural pressure is greater. The balance between these effects, however, may be altered. When the abdomen is given a mechanical support, the insertional and appositional forces are increased, so that the muscle produces a larger expansion of the lower rib cage and, with it, a smaller retraction of the upper rib cage. In contrast, at higher lung volumes the zone of apposition is decreased, and pleural pressure is the dominant force on the lower ribs as well. Consequently, although the force exerted by the diaphragm on these ribs remains inspiratory, rib displacement is reversed into a caudal-inward displacement. This mechanism likely explains the inspiratory retraction of the lateral walls of the lower rib cage observed in many subjects with chronic obstructive pulmonary disease (Hoover's sign). These observations support the use of a three-compartment, rather than a two-compartment, model to describe chest wall mechanics.

Perspective: Does Laboratory-Based Maximal Incremental Exercise Testing Elicit Maximum Physiological Responses in Highly-Trained Athletes with Cervical Spinal Cord Injury?

The physiological assessment of highly-trained athletes is a cornerstone of many scientific support programs. In the present article, we provide original data followed by our perspective on the topic of laboratory-based incremental exercise testing in elite athletes with cervical spinal cord injury. We retrospectively reviewed our data on Great Britain Wheelchair Rugby athletes collected during the last two Paralympic cycles. We extracted and compared peak cardiometabolic (heart rate and blood lactate) responses between a standard laboratory-based incremental exercise test on a treadmill and two different maximal field tests (4 min and 40 min maximal push). In the nine athletes studied, both field tests elicited higher peak responses than the laboratory-based test. The present data imply that laboratory-based incremental protocols preclude the attainment of true peak cardiometabolic responses. This may be due to the different locomotor patterns required to sustain wheelchair propulsion during treadmill exercise or that maximal incremental treadmill protocols only require individuals to exercise at or near maximal exhaustion for a relatively short period of time. We acknowledge that both field- and laboratory-based testing have respective merits and pitfalls and suggest that the choice of test be dictated by the question at hand: if true peak responses are required then field-based testing is warranted, whereas laboratory-based testing may be more appropriate for obtaining cardiometabolic responses across a range of standardized exercise intensities.