Thermoregulatory responses during competitive wheelchair rugby match play

The purpose of this study was to determine whether a player’s physical impairment or activity profile was related to the amount of thermal strain experienced during wheelchair rugby match play. 17 elite wheelchair rugby players played a competitive match, whilst activity profiles, measures of core and skin temperature, heart rate and perceptual responses were taken. Players were divided into 2 groups depending on their physical impairment: players with a cervical spinal cord injury, (n=10) or non-spinal related physical impairment (n=7). Total distance was lower (4 842±324 vs. 5 541±316 m, p<0.01, ES=2.2) and mean speed slower (1.13±0.11 vs. 1.27±0.11 m∙s−1, p<0.03, ES=1.3) in players with a spinal cord injury. Yet, the change in core temperature (1.6±0.4 vs. 0.7±0.3°C, p<0.01, ES=2.5) was significantly greater in players with a spinal cord injury. In conclusion, players with a spinal cord injury were under greater thermal strain during wheelchair rugby match play, as a result of their reduced heat loss capacity, due to their physical impairment and not because of their activity profile

Validity and reliability of an inertial sensor for wheelchair court sports performance

The purpose of the current study was to determine the validity and reliability of an inertial sensor for assessing speed specific to athletes competing in the wheelchair court sports (basketball, rugby, and tennis). A wireless inertial sensor was attached to the axle of a sports wheelchair. Over two separate sessions, the sensor was tested across a range of treadmill speeds reflective of the court sports (1.0 to 6.0 m/s). At each test speed, ten 10-second trials were recorded and were compared with the treadmill (criterion). A further session explored the dynamic validity and reliability of the sensor during a sprinting task on a wheelchair ergometer compared with high-speed video (criterion). During session one, the sensor marginally overestimated speed, whereas during session two these speeds were underestimated slightly. However, systematic bias and absolute random errors never exceeded 0.058 m/s and 0.086 m/s, respectively, across both sessions. The sensor was also shown to be a reliable device with coefficients of variation (% CV) never exceeding 0.9 at any speed. During maximal sprinting, the sensor also provided a valid representation of the peak speeds reached (1.6% CV). Slight random errors in timing led to larger random errors in the detection of deceleration values. The results of this investigation have demonstrated that an inertial sensor developed for sports wheelchair applications provided a valid and reliable assessment of the speeds typically experienced by wheelchair athletes. As such, this device will be a valuable monitoring tool for assessing aspects of linear wheelchair performance

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

West CR, Goosey-Tolfrey VL, Campbell IG, Romer LM. Effect of abdominal binding on respiratory mechanics during exercise in athletes with cervical spinal cord injury. J Appl Physiol 117: 36–45, 2014. First published May 22, 2014; doi:10.1152/japplphysiol.00218.2014.—We asked whether elastic binding of the abdomen influences respiratory mechanics during wheelchair propulsion in athletes with cervical spinal cord injury (SCI). Eight Paralympic wheelchair rugby players with motor-complete SCI (C5-C7) performed submaximal and maximal incremental exercise tests on a treadmill, both with and without abdominal binding. Measurements included pulmonary function, pressure-derived indices of respiratory mechanics, operating lung volumes, tidal flow-volume data, gas exchange, blood lactate, and symptoms. Residual volume and functional residual capacity were reduced with binding (77 18 and 81 11% of unbound, P 0.05), vital capacity was increased (114 9%, P 0.05), whereas total lung capacity was relatively well preserved (99 5%). During exercise, binding introduced a passive increase in transdiaphragmatic pressure, due primarily to an increase in gastric pressure. Active pressures during inspiration were similar across conditions. A sudden, sustained rise in operating lung volumes was evident in the unbound condition, and these volumes were shifted downward with binding. Expiratory flow limitation did not occur in any subject and there was substantial reserve to increase flow and volume in both conditions. V ˙ O2 was elevated with binding during the final stages of exercise (8 –12%, P 0.05), whereas blood lactate concentration was reduced (16 –19%, P 0.05). V ˙ O2/heart rate slopes were less steep with binding (62 35 vs. 47 24 ml/beat, P 0.05). Ventilation, symptoms, and work rates were similar across conditions. The results suggest that abdominal binding shifts tidal breathing to lower lung volumes without influencing flow limitation, symptoms, or exercise tolerance. Changes in respiratory mechanics with binding may benefit O2 transport capacity by an improvement in central circulatory function.This article has been made available through the Brunel Open Access Publishing Fund

Releasing The Anti-inflammatory Potential of Paralysed Skeletal Muscle: The Circulating Cytokine Response to Voluntary Upper-limb Exercise With/Without The Addition of Functional Electrical Stimulation (FES)-evoked Lower-limb Contractions

Skeletal muscle is a rich store of inflammatory mediating ‘myokines’. Following release from contracting muscle, the myokine interleukin-6 (IL-6) promotes a circulating anti-inflammatory environment associated with a reduced risk of cardiovascular disease (CVD). The metabolic and functional consequences of lower-limb paralysis, including the gain in relative adiposity and physical inactivity, result in a high prevalence of CVD in individuals with a spinal cord injury (SCI). However, the magnitude of any contraction-induced myokine response in this population may be limited by the small active muscle mass of the upper-limb. The combination of voluntary, upper-limb exercise and involuntary, functional electrical stimulation (FES)-evoked lower-limb cycling termed ‘hybrid’ exercise, may augment the acute myokine response by activating a greater volume of muscle mass than upper-limb exercise alone. Five community-based individuals with motor complete, thoracic SCI (Age=44±15 years; Body mass=66.6±14.3 kg) and at least 3 months FES-evoked cycling experience volunteered to participate. On separate occasions, each participant performed 30 min of voluntary upper-limb, hand cycling exercise with (HYBRID) and without (ARM only) the addition of FES-evoked lower-limb cycling at a fixed workload. Blood samples were collected at rest, immediately post-exercise, and 1 and 2 h post-exercise. Plasma concentrations of IL-6, IL-10 and IL-1ra were subsequently determined by enzyme linked immunoassay. Estimated energy expenditure was significantly higher in HYBRID (154±25 kcal) than ARM (132±21 kcal) (P=0.01; ES=0.90). Plasma IL-6 concentrations were significantly elevated following HYBRID, with values 1 h and 2 h post-exercise significantly higher than rest and immediately post-exercise (P\u3c0.04). A small (~50%) non-significant increase in IL-6 was present 1 h and 2 h post-exercise following ARM, however concentrations were significantly higher in HYBRID than ARM at the same time points (P\u3c0.02). Plasma IL-10 concentrations were unaffected by exercise in ARM. Although not attaining statistical significance, there was a tendency for IL-10 concentrations to rise in HYBRID, with an 85% increase in IL-10 concentrations at 2 h post exercise. Plasma IL-1ra was unaffected by exercise in both trials. Initial findings suggest paralysed skeletal muscle releases the myokine IL-6 in response to electrically evoked contractions. Further, voluntary upper-limb exercise combined with involuntary lower-limb FES-evoked exercise had the tendency to elevate plasma concentrations of the anti-inflammatory cytokine IL-10; this effect was not present when performing arm exercise alone. Hybrid exercise may offer a method of maximising the anti-inflammatory potential of acute exercise in individuals with a SCI. The current findings require verification in a larger cohort

The validity and reliability of a novel indoor player tracking system for use within wheelchair court sports

The aim of the current study was to investigate the validity and reliability of a radio- frequency based system for accurately tracking athlete movement within the wheelchair court sports. Four wheelchair specific tests were devised to assess the system during i) static measurements ii) incremental fixed speeds iii) peak speeds, and iv) multi-directional movements. During each test, three sampling frequencies (4, 8 & 16 Hz) were compared to a criterion method for distance, mean and peak speeds. Absolute static error remained between 0.19-0.32 m across the session. Distance values (test ii) showed greatest relative error in 4 Hz tags (1.3%), with significantly lower errors seen in higher frequency tags (< 1.0%). Relative peak speed errors of < 2.0% (test iii) were revealed across all sampling frequencies in relation to the criterion (4.00 ± 0.09 m·sˉ¹). Results showed 8 and 16 Hz sampling frequencies displayed the closest to criterion values, whilst intra-tag reliability never exceeded 2.0% coefficient of variation (% CV) during peak speed detection. Minimal relative distance errors (< 0.2%) were also seen across sampling frequencies (test iv). To conclude, the indoor tracking system is deemed an acceptable tool for tracking wheelchair court match-play using a tag frequency of 8 or 16 Hz

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 standardised exercise intensities

A comparison of speed profiles during training and competition in elite wheelchair rugby players

Purpose: To investigate the speed profiles of individual training modes in comparison to wheelchair rugby (WCR) competition across player classifications. Methods: Speed profiles of fifteen international WCR players were determined using a radio-frequency based indoor tracking system. Mean and peak speed (m∙s-1), work-rest ratios, the relative time spent (%)and the number of high speed activities performed were measured across training sessions (n = 464) and international competition (n = 34). Training was classified into one of four modes: conditioning (n = 71), skill-based (n = 133), game related (n = 151) and game-simulation drills (n = 109). Game-simulation drills were further categorised by the structured duration, which were 3-minute game-clock (n = 44), 8-minute game-clock (n = 39), and 10-minute running-clock (n = 26). Players were grouped by their International Wheelchair Rugby Federation classification as either low-point (≤ 1.5; n = 8) or high-point players (≥ 2.0; n = 7). Results: Conditioning drills were shown to exceed the demands of competition, irrespective of classification (P ≤ 0.005; effect size [ES] = 0.6-2.0). Skill-based and game related drills under-represented the speed profiles of competition (P ≤ 0.005; ES = 0.5-1.1). Mean speed and work-rest ratios were significantly lower during 3- and 8-minute game simulation drills in relation to competition (P ≤ 0.039; ES = 0.5-0.7). However, no significant differences were identified between the 10-minute running-clock and competition. Conclusions: Although game-simulation drills provided the closest representation of competition, the structured duration appeared important since the 10-minute running-clock increased training specificity. Coaches can therefore modify the desired training response by making subtle changes to the format of game-simulation drills

Individualised internal and external training load relationships in elite wheelchair rugby players

Aim: The quantification and longitudinal monitoring of athlete training load (TL) provides a scientific explanation for changes in performance and helps manage injury/illness risk. The aim of the present study was to establish the relationship between measures of internal (heart rate (HR) and session RPE (sRPE)) and external TL specific to wheelchair rugby (WR). Methods: Fourteen international WR athletes (age = 29 ± 7 yrs; body mass = 58.9 ± 10.9 kg) were monitored during 18 training sessions over a 3 month period. Activity profiles were collected during each training session using a radio-frequency based indoor tracking system. External TL was quantified by total distance (m) covered as well as time spent and distance covered in a range of classification-specific arbitrary speed zones. Banister’s TRIMP, Edwards’s summated HR zone (SHRZ) and Lucia’s TRIMP methods were used to quantify physiological internal TL. sRPE was calculated as the product of session duration multiplied by perceived exertion using the Borg CR10 scale. Relationships between external and internal TL were examined using correlation coefficients and the 90% confidence intervals (90% CI). Results: sRPE (r=0.59) and all HR-based (r >0.80) methods showed large and very large relationships with the total distance covered during training sessions, respectively. Large and very large correlations (r =0.56-0.82) were also observed between all measures of internal TL and times spent and distances covered in low and moderate intensity speed zones. HR-based methods showed very large relationships with time (r=0.71-0.75) and distance (r=0.70-0.73) in the very high speed zone and a large relationship with the number of high intensity activities performed (r=0.56-0.62). Weaker relationships (r=0.32–0.35) were observed between sRPE and all measures of high intensity activity. A large variation of individual correlation co-efficient was observed between sRPE and all external TL measures. Conclusion: The current findings suggest that sRPE and HR-based internal TL measures provide a valid tool for quantifying volume of external TL during WR training but may underestimate high intensity activities. It is recommended both internal and external TL measures are employed for the monitoring of overall TL during court-based training in elite WR athletes