The aerobic performance of trained and untrained handcyclists with spinal cord injury

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.

Characterization of muscle oxygenation response in well-trained handcyclists

PURPOSE

 Peripheral responses might be important in handcycling, given the involvement of small muscles compared to other exercise modalities. Therefore, the goal of this study was to compare changes in muscle oxygen saturation (∆SmO2) and deoxyhemoglobin level (∆[HHb]) between different efforts and muscles.

METHODS

 Handcyclists participated in a Wingate, a maximal incremental test and a 20-min time-trial (TT). Oxygen uptake (VO2) as well as ∆SmO2, ∆[HHb], deoxygenation and reoxygenation rates in the triceps brachii (TB), biceps brachii (BB), anterior deltoid (AD) and extensor carpi radialis brevis (ER) were measured.

RESULTS

 ER ∆[HHb]max was 37% greater in the incremental test than in the Wingate (ES = 0.392, P = 0.031). TT mean power (W/kg) was associated with BB ∆SmO2min measured in the incremental test (r = -0.998 [-1.190, -0.806], P = 0.002) and in the Wingate (r = -0.994 [-1.327, -0.661], P = 0.006). MAP (W/kg) was associated with Wingate BB ∆SmO2min (r = -0.983 [-0.999, -0.839], P = 0.003), and Wingate peak (r = 0.649 [0.379, 0.895], P = 0.008) and mean power (W/kg) (r = 0.925 [0.752, 0.972], P = 0.003) was associated with right handgrip force. The strongest physiological predictor for TT performance was BB ∆SmO2min in the incremental test (P = 0.002, r2 = 0.993, SEE 0.016 W/kg), Wingate BB ∆SmO2min for MAP (P = 0.003, r2 = 0.956, SEE 0.058 W/kg) and right handgrip force for Wingate peak power (P = 0.005, r2 = 0.856, SEE 0.551 W/kg).

CONCLUSION

 Peripheral aerobic responses (muscle oxygenation) were predictive of handcycling performance.

The Science of Handcycling: A Narrative Review

The aim of this narrative review is to provide insight as to the history, biomechanics, and physiological characteristics of competitive handcycling. Furthermore, based upon the limited evidence available, this paper aims to provide practical training suggestions by which to develop competitive handcycling performance. Handbike configuration, individual physiological characteristics, and training history all play a significant role in determining competitive handcycling performance. Optimal handcycling technique is highly dependent upon handbike configuration. As such, seat positioning, crank height, crank fore-aft position, crank length, and handgrip position must all be individually configured. In regard to physiological determinants, power output at a fixed blood lactate concentration of 4 mmol·L−1, relative oxygen consumption, peak aerobic power output, relative upper body strength, and maximal anaerobic power output have all been demonstrated to impact upon handcycling performance capabilities. Therefore, it is suggested that that an emphasis be placed upon the development and frequent monitoring of these parameters. Finally, linked to handcycling training, it is suggested that handcyclists should consider adopting a concurrent strength and endurance training approach, based upon a block periodization model that employs a mixture of endurance, threshold, interval, and strength training sessions. Despite our findings, it is clear that several gaps in our scientific knowledge of handcycling remain and that further research is necessary in order to improve our understanding of factors that determine optimal performance of competitive handcyclists. Finally, further longitudinal research is required across all classifications to study the effects of different training programs upon handcycling performance.

A Role for Trunk Function in Elite Recumbent Handcycling Performance?

Handcycling classification considers trunk function, but there is limited scientific evidence of trunk involvement in recumbent performance. This study investigated the association between trunk function and recumbent handcycling performance of athletes without upper-limb impairments (H3-H4 sport classes). The study was divided into two parts. First, 528 time-trial results from 81 handcyclists with spinal cord injury (SCI) were obtained between 2014 and 2020. Average time-trial velocity was used as performance measure and SCI level as trunk function determinant. Multilevel regression analysis was performed to analyse differences in performance among SCI groups while correcting for lesion completeness, sex, and age. Second, in 26 handcyclists, standardised trunk flexion strength was measured with a handheld dynamometer. Peak and mean power-output from a sprint test and time-trial average velocity were used as performance measures. Spearman correlations were conducted to investigate the association between trunk strength and performance. Results showed that the different SCI groups did not exhibit significant differences in performance. Furthermore, trunk flexion strength and performance exhibited non-significant weak to moderate correlations (for time-trial speed: rs = 0.36; p = 0.07). Results of both analyses suggest that trunk flexion strength does not seem to significantly impact recumbent handcycling performance in athletes without upper-limb impairments.

The Effectiveness of a 30-Week Concurrent Strength and Endurance Training Program in Preparation for an Ultra-Endurance Handcycling Challenge: A Case Study

PURPOSE

The aim of the following case study was to evaluate the effectiveness of a 30-week concurrent strength and endurance training program designed to prepare a trained H4 male handcyclist (aged 28 y, bilateral, above knee amputee, and body mass 65.6 kg) for a 1407-km ultra-endurance handcycling challenge.

METHODS

This observational case study tracked selected physiological measures, training intensity distribution, and total training load over the course of a 30-week concurrent training protocol. Furthermore, the athlete's performance profile during the ultra-endurance challenge was monitored with power output, cadence, speed, and heart rate recorded throughout.

RESULTS

Findings revealed considerable improvements in power output at a fixed blood lactate concentration of 4 mmol·L-1 (+25.7%), peak aerobic power output (+18.9%), power-to-mass ratio (+18.3%), relative peak oxygen uptake (+13.9%), gross mechanical efficiency (+4.6%), bench press 1-repetition maximum (+4.3%), and prone bench pull 1-repetition maximum (+14.9%). The athlete completed the 1407-km route in a new handcycling world record time of 89:55 hours. Average speed was 18.7 (2.1) km·h-1; cadence averaged 70.0 (2.6) rpm, while average power output was 67 (12) W. In terms of internal load, the athlete's average heart rate was 111 (11) beats per minute.

CONCLUSION

These findings demonstrate how a long-term concurrent strength and endurance training program can be used to optimize handcycling performance capabilities in preparation for an ultra-endurance cycling event. Knowledge emerging from this case study provides valuable information that can guide best practices with respect to handcycling training for ultra-endurance events.

The Relationship Between Absolute and Relative Upper-Body Strength and Handcycling Performance Capabilities

PURPOSE

To explore the relationship between absolute and relative upper-body strength and selected measures of handcycling performance.

METHODS

A total of 13 trained H3/H4-classified male handcyclists (mean [SD] age 37 [11] y; body mass 76.6 [10.1] kg; peak oxygen consumption 2.8 [0.6] L·min-1; relative peak oxygen consumption 36.5 [10] mL·kg·min-1) performed a prone bench-pull and bench-press 1-repetition-maximum strength assessment, a 15-km individual time trial, a graded exercise test, and a 15-second all-out sprint test. Relationships between all variables were assessed using Pearson correlation coefficient.

RESULTS

Absolute strength measures displayed a large correlation with gross mechanical efficiency and maximum anaerobic power output (P = .05). However, only a small to moderate relationship was identified with all other measures. In contrast, relative strength measures demonstrated large to very large correlations with gross mechanical efficiency, 15-km time-trial velocity, maximum anaerobic power output, peak aerobic power output, power at a fixed blood lactate concentration of 4 mmol·L-1, and peak oxygen consumption (P = .05).

CONCLUSION

Relative upper-body strength demonstrates a significant relationship with time-trial velocity and several handcycling performance measures. Relative strength is the product of one's ability to generate maximal forces relative to body mass. Therefore, the development of one's absolute strength combined with a reduction in body mass may influence real-world handcycling race performance.

The Anthropometric, Physiological, and Strength-Related Determinants of Handcycling 15-km Time-Trial Performance

PURPOSE

The aim of this study was to investigate the relationship between selected anthropometric, physiological, and upper-body strength measures and 15-km handcycling time-trial (TT) performance.

METHODS

Thirteen trained H3/H4 male handcyclists performed a 15-km TT, graded exercise test, 15-second all-out sprint, and 1-repetition-maximum assessment of bench press and prone bench pull strength. Relationship between all variables was assessed using a Pearson correlation coefficient matrix with mean TT velocity representing the principal performance outcome.

RESULTS

Power at a fixed blood lactate concentration of 4 mmol·L-1 (r = .927; P < .01) showed an extremely large correlation with TT performance, whereas relative V˙O2peak (peak oxygen uptake) (r = .879; P < .01), power-to-mass ratio (r = .879; P < .01), peak aerobic power (r = .851; P < .01), gross mechanical efficiency (r = 733; P < .01), relative prone bench pull strength (r = .770; P = .03) relative bench press strength (r = .703; P = .11), and maximum anaerobic power (r = .678; P = .15) all demonstrated a very large correlation with performance outcomes.

CONCLUSION

Findings of this study indicate that power at a fixed blood lactate concentration of 4 mmol·L-1, relative V˙O2peak, power-to-mass ratio, peak aerobic power, gross mechanical efficiency, relative upper-body strength, and maximum anaerobic power are all significant determinants of 15-km TT performance in H3/H4 handcyclists.

Physiological responses during simulated 16 km recumbent handcycling time trial and determinants of performance in trained handcyclists

Purpose

To characterise the physiological profiles of trained handcyclists, during recumbent handcycling, to describe the physiological responses during a 16 km time trial (TT) and to identify the determinants of this TT performance.

Methods

Eleven male handcyclists performed a sub-maximal and maximal incremental exercise test in their recumbent handbike, attached to a Cyclus II ergometer. A physiological profile, including peak aerobic power output (PO_Peak), peak rate of oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2Peak), aerobic lactate threshold (AeLT) and PO at 4 mmol L⁻¹ (PO₄), were determined. Participants also completed a 16 km simulated TT using the same experimental set-up. Determinants of TT performance were identified using stepwise multiple linear regression analysis.

Results

Mean values of PO_Peak = 252 ± 9 W, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2Peak = 3.30 ± 0.36 L min⁻¹ (47.0 ± 6.8 mL kg⁻¹ min⁻¹), AeLT = 87 ± 13 W and PO₄ = 154 ± 14 W were recorded. The TT was completed in 29:21 ± 0:59 min:s at an intensity equivalent to 69 ± 4% PO_Peak and 87 ± 5% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2Peak. PO_Peak (r = − 0.77, P = 0.006), PO₄ (r = − 0.77, P = 0.006) and AeLT (r = − 0.68, P = 0.022) were significantly correlated with TT performance. PO₄ and PO_Peak were identified as the best predictors of TT performance (r = 0.89, P < 0.001).

Conclusion

PO_Peak, PO₄ and AeLT are important physiological TT performance determinants in trained handcyclists, differentiating between superior and inferior performance, whereas \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2peak was not. The TT took place at an intensity corresponding to 69% PO_Peak and 87% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2peak.

Bioenergetics and Biomechanics of Handcycling at Submaximal Speeds in Athletes with a Spinal Cord Injury

BACKGROUND

A study aimed at comparing bioenergetics and biomechanical parameters between athletes with tetraplegia and paraplegia riding race handbikes at submaximal speeds in ecological conditions.

METHODS

Five athletes with tetraplegia (C6-T1, 43 ± 6 yrs, 63 ± 14 kg) and 12 athletes with paraplegia (T4-S5, 44 ± 7 yrs, 72 ± 12 kg) rode their handbikes at submaximal speeds under metabolic measurements. A deceleration method (coasting down) was applied to calculate the rolling resistance and frontal picture of each participant was taken to calculate air resistance. The net overall Mechanical Efficiency (Eff) was calculated by dividing external mechanical work to the corresponding Metabolic Power.

RESULTS

Athletes with tetraplegia reached a lower aerobic speed (4.7 ± 0.6 m s^-1 vs. 7.1 ± 0.9 m s^-1, P = 0.001) and Mechanical Power (54 ± 15 W vs. 111 ± 25 W, P = 0.001) compared with athletes with paraplegia. The metabolic cost was around 1 J kg^-1 m^-1 for both groups. The Eff values (17 ± 2% vs. 19 ± 3%, P = 0.262) suggested that the handbike is an efficient assisted locomotion device.

CONCLUSION

Handbikers with tetraplegia showed lower aerobic performances but a similar metabolic cost compared with handbikers with paraplegia at submaximal speeds in ecological conditions.

Comparison of Different Blood Lactate Threshold Concepts for Constant Load Performance Prediction in Spinal Cord Injured Handcyclists

Background

Endurance capacity is one of the main performance determinants in handcycling. There are two exercise test procedures primarily applied to determine endurance capacity, to verify training adaptations and predict race performance. This study aims to evaluate the agreement of these applied concepts in handcycling.

Methods

In a repeated measures cross-over design, 11 highly trained male spinal cord injured (Th12 to L1) handcyclists (age: 40 ± 9 years, height: 183 ± 8 cm, body mass: 73.2 ± 8.5 kg) performed a graded exercise test (GXT) and a lactate minimum test (LMT) to determine lactate threshold at 4 mmol L^–1 (LT_{4 mmol L}−1) and lactate minimum (LM)_, respectively. The agreement of both lactate thresholds concepts for constant load performance prediction (change of ≤ 1 mmol L^–1 during the last 20 min) was evaluated within constant load tests (CLT; 30 min) at a power output (PO) corresponding to LT_{4 mmol L–1} and LM. Oxygen uptake (V.⁢O2), respiratory exchange ratio (RER), heart rate (HR) and blood lactate (La) were measured during all tests.

Results

Power output at the corresponding thresholds (LT_{4 mmol L}−₁: 149 ± 34 W vs. LM: 137 ± 18 W) revealed no significant difference (p = 0.06). During the CLT at LT_{4 mmol⋅L}−₁ and LM, V.⁢O2, and RPE were not significantly different. However, LA, RER, and HR were significantly higher (p ≤ 0.02) during CLT at LT_{4 mmol L}−¹. Bland–Altman plots indicate a wide range of dispersion for all parameters between both lactate threshold concepts. Evaluations of LT_{4 mmol L}−₁ and LM did not meet the criteria for constant load performance within the CLT for 33 and 17% of the athletes, respectively.

Discussion

Both exercise tests and the corresponding lactate threshold concept revealed appropriate estimates to predict a steady state performance for the majority of participants. However, as PO determination at LT_{4 mmol L}−₁ and LM exceeds the criteria for constant load performance (increase of ≥ 1 mmol L^–1) for 33 and 17% respectively the current results indicate the common criteria for constant load performance (change of ± 1 mmol L^–1) might not be sufficiently precise for elite athletes in handcycling. Consequently, exercise test results of elite athletes should be analyzed individually and verified by means of several CLT.

Defining accelerometer cut-points for different intensity levels in motor-complete spinal cord injury

STUDY DESIGN

Descriptive.

OBJECTIVE

The present aim was to define accelerometer cut-point values for wrist-worn accelerometers to identify absolute- and relative-intensity physical activity (PA) levels in people with motor-complete paraplegics (PP) and tetraplegics (TP).

SETTINGS

Rehabilitation facility in Sweden.

METHODS

The participants were 26 (19 men, 7 women) with C5-C8, AIS A and B (TP) and 37 (27 men, 10 women) with T7-T12 (PP), AIS A and B. Wrist-worn accelerometer recordings (Actigraph GT3X+) were taken during seven standardized activities. Oxygen consumption was measured, as well as at-rest and peak effort, with indirect calorimetry. Accelerometer cut-points for absolute and relative intensities were defined using ROC-curve analyses.

RESULTS

The ROC-curve analyses for accelerometer cut-points revealed good-to-excellent accuracy (AUC >0.8), defining cut-points for absolute intensity (2, 3, 4, 5, 6, 7 METs for PP and 2 to 6 METs for TP) and relative intensity (30, 40, 50, 60, 70, and 80% for PP and 40-80% for TP). The cut-points for moderate-to-vigorous physical activity was defined as ≥9515 vector magnitude counts per minute (VMC) for PP and ≥4887 VMC/min for TP.

CONCLUSION

This study presents cut-points for wrist-worn accelerometers in both PP and TP, which could be used in clinical practice to describe physical activity patterns and time spent at different intensity levels.

Exercise testing protocol using a roller system for manual wheelchair users with spinal cord injury

OBJECTIVE

Determine the validity and reliability of an exercise testing protocol to evaluate cardiorespiratory measures in manual wheelchair users (MWUs) with spinal cord injury (SCI) using a roller-based (RS) wheelchair system.

DESIGN

Repeated measures within-subject design.

SETTING

Community-based research laboratory.

PARTICIPANTS

Ten adults with SCI requiring the use of a manual wheelchair.

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

Cardiorespiratory measures (peak oxygen consumption [VO₂peak], respiratory exchange ratio [RER], pulmonary ventilation [VE], energy expenditure [EE], heart rate [HR], accumulated kilocalories [AcKcal]) and perceived exertion (RPE) were measured during three separate maximal exercise tests using an arm crank ergometer (ACE) and an RS.

RESULTS

At maximal exertion, there were no significant differences in variables between groups, with moderate-to-strong correlations (P < 0.05, r = 0.79-0.90) for VO₂, HR, RPE, AcKcal, and rate of EE between RS and ACE trials. Significant moderate-to-strong correlations existed between RS trials for VO₂, AcKcal, rate of EE, and peak power output (P < 0.01, r = 0.77-0.97).

CONCLUSIONS

VO_2peak was highly correlated between ACE and RS trials and between the two RS trials, indicating the RS protocol to be reliable and valid for MWUs with SCI. Differences in perceived exertion and efficiency at submaximal workloads and maximal pulmonary ventilation at peak workloads indicated potential advantages to using the RS.

Shoulder and thorax kinematics contribute to increased power output of competitive handcyclists

Current knowledge of recumbent handbike configuration and handcycling technique is limited. The purpose of this study was to evaluate and compare the upper limb kinematics and handbike configurations of recreational and competitive recumbent handcyclists, during sport‐specific intensities. Thirteen handcyclists were divided into two significantly different groups based on peak aerobic power output (PO_peak) and race experience; competitive (n = 7; 5 H3 and 2 H4 classes; PO_peak: 247 ± 20 W) and recreational (n = 6; 4 H3 and 2 H4 classes; PO_peak: 198 ± 21 W). Participants performed bouts of exercise at training (50% PO_peak), competition (70% PO_peak), and sprint intensity while three‐dimensional kinematic data (thorax, scapula, shoulder, elbow, and wrist) were collected. Statistical parametric mapping was used to compare the kinematics of competitive and recreational handcyclists. Handbike configurations were determined from additional markers on the handbike. Competitive handcyclists flexed their thorax (~5°, P < 0.05), extended their shoulder (~10°, P < 0.01), and posteriorly tilted their scapular (~15°, P < 0.05) more than recreational handcyclists. Differences in scapular motion occurred only at training intensity while differences in shoulder extension and thorax flexion occurred both at training and competition intensities. No differences were observed during sprinting. No significant differences in handbike configuration were identified. This study is the first to compare the upper limb kinematics of competitive recreational handcyclists at sport‐specific intensities. Competitive handcyclists employed significantly different propulsion strategies at training and competition intensities. Since no differences in handbike configuration were identified, these kinematic differences could be due to technical training adaptations potentially optimizing muscle recruitment or force generation of the arm.

Elite handcycling: a qualitative analysis of recumbent handbike configuration for optimal sports performance

Our understanding of handbike configuration is limited, yet it can be a key determinant of performance in handcycling. This study explored how 14 handcycling experts (elite handcyclists, coaches, support staff, and manufacturers) perceived aspects of recumbent handbike configuration to impact upon endurance performance via semi-structured interviews. Optimising the handbike for comfort, stability, and power production was identified as key themes. Comfort and stability were identified to be the foundations of endurance performance and were primarily influenced by the seat, backrest, headrest, and their associated padding. Power production was determined by the relationship between the athletes' shoulder and abdomen and the trajectories of the handgrips, which were determined by the crank axis position, crank arm length, and handgrip width. Future studies should focus on quantifying the configuration of recumbent handbikes before determining the effects that crank arm length, handgrip width, and crank position have on endurance performance. Practitioner Summary: To gain a greater understanding of the impact of handbike configurations on endurance performance, the perceptions of expert handcyclists were explored qualitatively. Optimising the handbike for comfort and stability, primarily via backrest padding and power production, the position of the shoulders relative to handgrips and crank axis, were critical.

Interrater and intrarater reliability of ventilatory thresholds determined in individuals with spinal cord injury

STUDY DESIGN

Cross-sectional.

OBJECTIVES

Individualized training regimes are often based on ventilatory thresholds (VTs). The objectives were to study: (1) whether VTs during arm ergometry could be determined in individuals with spinal cord injury (SCI), (2) the intrarater and interrater reliability of VT determination.

SETTING

University research laboratory.

METHODS

Thirty graded arm crank ergometry exercise tests with 1-min increments of recreationally active individuals (tetraplegia (N = 11), paraplegia (N = 19)) were assessed. Two sports physicians assessed all tests blinded, randomly, in two sessions, for VT1 and VT2, resulting in 240 possible VTs. Power output (PO), heart rate (HR), and oxygen uptake (VO₂) at each VT were compared between sessions or raters using paired samples t-tests, Wilcoxon signed-rank tests, intraclass correlation coefficients (ICC, relative agreement), and Bland-Altman plots (random error, absolute agreement).

RESULTS

Of the 240 VTs, 217 (90%) could be determined. Of the 23 undetermined VTs, 2 (9%) were VT1 and 21 (91%) were VT2; 7 (30%) among individuals with paraplegia, and 16 (70%) among individuals with tetraplegia. For the successfully determined VTs, there were no systematic differences between sessions or raters. Intrarater and interrater ICCs for PO, HR, and VO₂ at each VT were high to very high (0.82-1.00). Random error was small to large within raters, and large between raters.

CONCLUSIONS

For VTs that could be determined, relative agreement was high to very high, absolute agreement varied. For some individuals, often with tetraplegia, VT determination was not possible, thus other methods should be considered to prescribe exercise intensity.

A new conceptual framework for the integrated neural control of locomotor and sympathetic function: implications for exercise after spinal cord injury

All mammals, including humans, are designed to produce sustained locomotor movements. Many higher centres are involved in movement, but ultimately these centres act upon a core "rhythm-generating" network within the brainstem-spinal cord. In addition, endurance-based locomotor exercise requires sympathetic neural support to maintain homeostasis and to provide needed metabolic resources. This review focuses on the roles and integration of these 2 neural systems. Part I reviews the cardiovascular, thermoregulatory, and metabolic functions under spinal sympathetic control as revealed by spinal cord injury at different levels. Part II examines the integration between brainstem-spinal sympathetic pathways and the neural circuitry producing motor rhythms. In particular, the rostroventral medulla (RVM) contains the neural circuitry that (i) integrates heart rate, contractility, and blood flow in response to postural changes; (ii) initiates and maintains cardiovascular adaptations for exercise; (iii) provides direct descending innervation to preganglionic neurons innervating the adrenal glands, white adipose tissue, and tissues responsible for cooling the body; (iv) integrates descending sympathetic drive for energy substrate mobilization (lipolysis); and (v) is the relay for descending locomotor commands arising from higher brain centres. A unifying conceptual framework is presented, in which the RVM serves as the final descending supraspinal "exercise integration centre" linking the descending locomotor command signal with the metabolic and homeostatic support needed to produce prolonged rhythmic activities. The role and rationale for an ascending sympathetic and locomotor drive from the lower to upper limbs within this framework is presented. Examples of new research directions based on this unifying framework are discussed.

Peak power output in handcycling of individuals with a chronic spinal cord injury: predictive modeling, validation and reference values

Purpose: To develop and validate predictive models for peak power output to provide guidelines for individualized handcycling graded exercise test protocols for people with spinal cord injury (SCI); and to define reference values.Materials and methods: Power output was measured in 128 handcyclists with SCI during a synchronous handcycling exercise test. Eighty percent of the data was used to develop four linear regression models: two theoretical and two statistical models with peak power output (in W and W/kg) as dependent variable. The other 20% of the data was used to determine agreement between predicted versus measured power output. Reference values were based on percentiles for the whole group.Results: Lesion level, handcycling training hours and sex or body mass index were significant determinants of peak power output. Theoretical models (R² = 42%) were superior to statistical models (R²=39% for power output in W, R² = 30% for power output in W/kg). The intraclass correlation coefficients varied between 0.35 and 0.60, depending on the model. Absolute agreement was low.Conclusions: Both models and reference values provide insight in physical capacity of people with SCI in handcycling. However, due to the large part of unexplained variance and low absolute agreement, they should be used with caution. Implications for rehabilitationIndividualization of the graded exercise test protocol is very important to attain the true peak physical capacity in individuals with spinal cord injury.The main determinants to predict peak power output during a handcycling graded exercise test for individuals with a spinal cord injury are lesion level, handcycling training hours and sex or body mass index.The predictive models for peak power output should be used with caution and should not replace a graded exercise test.

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.

High Intensity Interval Training in Handcycling: The Effects of a 7 Week Training Intervention in Able-bodied Men

Introduction: In lower body endurance training, quantities of both moderate intensity continuous training (MICT) and high intensity interval training (HIIT) can lead to an improved physiological capacity and performance. Limited research is available regarding the endurance and muscular capacity of the upper body, and how training contributes to improvements in performance capacity is still unknown. The aim of the current study was to evaluate the effects of HIIT and MICT on the physiological capacity and handcycling performance of able-bodied men in a well-controlled laboratory setting.

Methods: Twenty four recreationally active men (22 ± 2 years; 1.84 ± 0.04 m; 79 ± 10 kg) were matched on incremental handcycling pre-test performance (peakPO) and then randomly assigned to HIIT, MICT, or a non-training control group (CON, 3 × n = 8). Participants in HIIT completed 14 interval training sessions, performing 4 × 4 min intervals at 85% heart rate reserve (%HRR), and seven continuous training sessions at 55 %HRR (every 2nd training session of the week). Participants in MICT performed 21 training sessions of 30 min at 55 %HRR. After the intervention, changes in peak oxygen uptake (peakVO₂) and peak power output (peakPO) were compared within and between HIIT, MICT and CON.

Results: The average external training load per training session did not differ between MICT and HIIT (p = 0.713). Improvements after HIIT in peakVO₂ (22.2 ± 8.1%) and peakPO (47.1 ± 20.7%) were significantly larger compared with MICT and CON (p < 0.001). Improvements after MICT in peakVO₂ (10.7 ± 12.9%) and peakPO (32.2 ± 8.1%) were higher compared to CON (p < 0.001). Higher improvement after HIIT occurred despite training 22% less time than MICT. No significant changes were found in CON.

Discussion: As in lower body endurance sports, HIIT proved to be very effective in improving the physiological and performance capacity of upper body exercise. Whilst physiological capacity in both training groups improved significantly compared with CON, the present study shows that peakVO₂ and peakPO improved more after HIIT than after MICT in able-bodied men. It is advised to include HIIT into training regimes of recreational and competitive handcyclists to improve the upper body endurance capacity.

Mountain time trial in handcycling: exercise intensity and predictors of race time in people with spinal cord injury

STUDY DESIGN

Cross-sectional analyses.

OBJECTIVES

To analyze exercise intensity during a mountain time trial in handcycling and to determine predictors of race time.

SETTING

Eight Dutch rehabilitation centers and Austrian mountain.

METHODS

Forty participants with spinal cord injury (SCI; high lesion level (>T6): N=11; low lesion level (⩽T6): N=29) handcycled a 20.2-km mountain time trial. Heart rate (HR) was monitored in 17 (high: N=5, low: N=12) participants during the race to determine exercise intensity, expressed relative to the heart rate reserve (%HRR). Two weeks before the race all participants completed laboratory tests to measure anthropometrics and peak values for power output (POpeak), oxygen uptake (VO2peak) and HR.

RESULTS

Mean race time was 4 h and 1 min (s.d.: 1 h and 24 min), with no difference in race time between lesion groups. Mean exercise intensity during the race was 70±7%HRR. Exercise was mainly (73% of the race time) at a vigorous intensity (60-89%HRR), with 29% of the total time in the 80-89%HRR zone. No clear differences were found in exercise intensities between lesion groups. The strongest predictors for better race times were higher mean %HRR during race (R(2)=57%), lower waist circumference (R(2)=39%), higher POpeak (R(2)=39%) and VO2peak (R(2)=32%).

CONCLUSION

A 20-km mountain time trial in a handcycle is intensive. Faster race times were achieved by those with a lower waist circumference, greater fitness level and ability to perform at higher average exercise intensities during the race. Level of SCI was not significantly associated with race time.

The contribution of energy systems during the upper body Wingate anaerobic test

The purpose of this study was to measure the contribution of the aerobic, anaerobic lactic, and alactic systems during an upper body Wingate Anaerobic test (WAnT). Oxygen uptake and blood lactate were measured before, during, and after the WAnT and body composition analyzed by dual-energy X-ray absorptiometry. The contribution of the energy systems was 11.4% ± 1.4%, 60.3% ± 5.6%, and 28.3% ± 4.9% for the aerobic, anaerobic lactic, and alactic systems, respectively.