Barry S. Mason

The Ergonomics of Wheelchair Configuration for Optimal Performance in the Wheelchair Court Sports

Optimizing mobility performance in wheelchair court sports (basketball, rugby and tennis) is dependent on a combination of factors associated with the user, the wheelchair and the interfacing between the two. Substantial research has been attributed to the wheelchair athlete yet very little has focused on the role of the wheelchair and the wheelchair-user combination. This article aims to review relevant scientific literature that has investigated the effects of wheelchair configuration on aspects of mobility performance from an ergonomics perspective. Optimizing performance from an ergonomics perspective requires a multidisciplinary approach. This has resulted in laboratory-based investigations incorporating a combination of physiological and biomechanical analyses to assess the efficiency, health/safety and comfort of various wheelchair configurations. To a lesser extent, field-based testing has also been incorporated to determine the effects of wheelchair configuration on aspects of mobility performance specific to the wheelchair court sports. The available literature has demonstrated that areas of seat positioning, rear wheel camber, wheel size and hand-rim configurations can all influence the ergonomics of wheelchair performance. Certain configurations have been found to elevate the physiological demand of wheelchair propulsion, others have been associated with an increased risk of injury and some have demonstrated favourable performance on court. A consideration of all these factors is required to identify optimal wheelchair configurations. Unfortunately, a wide variety of different methodologies have immerged between studies, many of which are accompanied by limitations, thus making the identification of optimal configurations problematic. When investigating an area of wheelchair configuration, many studies have failed to adequately standardize other areas, which has prevented reliable cause and effect relationships being established. In addition, a large number of studies have explored the effects of wheelchair configuration in either able-bodied populations or in daily life or racing wheelchairs. As such, the findings are not specific and transferable to athletes competing in the wheelchair court sports. This review presents evidence about the effects of wheelchair configuration on aspects of mobility performance specific to the wheelchair court sports to better inform athletes, coaches and manufacturers about the consequences of their selections. It also provides researchers with guidance on the design of future investigations into areas of wheelchair configuration, which are essential.

Influence of Glove Type on Mobility Performance for Wheelchair Rugby Players

Mason BS, van der Woude LHV, Goosey-Tolfrey VL: Influence of glove type on mobility performance for wheelchair rugby players. Objective:The purpose of this study was to determine the effectiveness of different glove types on mobility performance in a series of field tests specific to wheelchair rugby. Design:Ten international wheelchair rugby players performed three drills in each glove condition: (i) players’ current glove selection, (ii) American football glove, (iii) building glove, and (iv) new prototype glove. Performance was assessed by a combination of outcomes including test times, peak velocities, and accelerations within each drill. Peak velocities and accelerations were measured using a velocometer sampling at 100 Hz. Results:A two-way analysis of variance with repeated measures revealed that participants performed statistically better for measures of acceleration and sprinting when wearing their current choice of glove compared with the new prototype glove (P < 0.05). Subjective data identified that players also favored their current gloves compared with others, although slight discrepancies were evident among classification levels concerning the building gloves. Building gloves seemed to be less suited to low-point players because of the reduced grip and protection they provided. Conclusions:It may be concluded that participants’ current gloves that have been modified for the specific demands of wheelchair rugby are more effective for aspects of mobility performance than other glove types.

Activity profiles of elite wheelchair rugby players during competition.

PURPOSE To quantify the activity profiles of elite wheelchair rugby (WCR) players and establish classification-specific arbitrary speed zones. In addition, indicators of fatigue during full matches were explored. METHODS Seventy-five elite WCR players from 11 national teams were monitored using a radio-frequency-based, indoor tracking system across 2 international tournaments. Players who participated in complete quarters (n = 75) and full matches (n = 25) were included and grouped by their International Wheelchair Rugby Federation functional classification: groups I (0.5), II (1.0-1.5), III (2.0-2.5), and IV (3.0-3.5). RESULTS During a typical quarter, significant increases in total distance (m), relative distance (m/min), and mean speed (m/s) were associated with an increase in classification group (P < .001), with the exception of groups III and IV. However, group IV players achieved significantly higher peak speeds (3.82 ± 0.31 m/s) than groups I (2.99 ± 0.28 m/s), II (3.44 ± 0.26 m/s), and III (3.67 ± 0.32 m/s). Groups I and II differed significantly in match intensity during very-low/low-speed zones and the number of high-intensity activities in comparison with groups III and IV (P < .001). Full-match analysis revealed that activity profiles did not differ significantly between quarters. CONCLUSIONS Notable differences in the volume of activity were displayed across the functional classification groups. However, the specific on-court requirements of defensive (I and II) and offensive (III and IV) match roles appeared to influence the intensity of match activities, and consequently training prescription should be structured accordingly.

A physiological and biomechanical comparison of over-ground, treadmill and ergometer wheelchair propulsion

Abstract The purpose of the study was to determine which laboratory-based modality provides the most valid physiological and biomechanical representation of over-ground sports wheelchair propulsion. Fifteen able-bodied participants with previous experience of wheelchair propulsion performed a 3-minute exercise trial at three speeds (4, 6 and 8 km ∙ h–1) in three testing modalities over separate sessions: (i) over-ground propulsion on a wooden sprung surface; (ii) wheelchair ergometer propulsion; (iii) treadmill propulsion at four different gradients (0%, 0.7%, 1.0% and 1,3%). A 0.7% treadmill gradient was shown to best reflect the oxygen uptake (7.3 to 9.1% coefficient of variation (CV)) and heart rate responses (4.9 to 6.4% CV) of over-ground propulsion at 4 and 6 km ∙ h–1. A 1.0% treadmill gradient provided a more valid representation of oxygen uptake during over-ground propulsion at 8 km ∙ h–1 (8.6% CV). Physiological demand was significantly underestimated in the 0% gradient and overestimated in the 1.3% gradient and wheelchair ergometer trials compared to over-ground trials (P<0.05). No laboratory-based modality provided a valid representation of the forces applied during OG (≥ 18.4% CV). To conclude, a 0.7% treadmill gradient is recommended to replicate over-ground wheelchair propulsion at lower speeds (4 and 6 km ∙ h–1) whereas a 1.0% gradient may be more suitable at 8 km ∙ h–1.

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

Abstract 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 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) multidirectional movements. During each test, three sampling frequencies (4, 8 and 16 Hz) were compared to a criterion method for distance, mean and peak speeds. Absolute static error remained between 0.19 and 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.

The Effects of Rear-Wheel Camber on Maximal Effort Mobility Performance in Wheelchair Athletes

This study examined the effect of rear-wheel camber on maximal effort wheelchair mobility performance. 14 highly trained wheelchair court sport athletes performed a battery of field tests in 4 standardised camber settings (15°, 18°, 20°, 24°) with performance analysed using a velocometer. 20 m sprint times reduced in 18° (5.89±0.47 s, P=0.011) and 20° camber (5.93±0.47 s, P=0.030) compared with 24° (6.05±0.45 s). Large effect sizes revealed that 18° camber enabled greater acceleration over the first 2 (r=0.53, 95% CI=0.004 to 0.239) and 3 (r=0.59, 95% CI=0.017 to 0.170) pushes compared with 24°. Linear mobility times significantly improved (P≤0.05) in 15° (16.08±0.84 s), 18° (16.06±0.97 s) and 20° (16.22±0.84 s) camber compared with 24° (16.62±1.10 s). Although no statistically significant main effect of camber was revealed, large effect sizes (r=0.72, 95% CI=0.066 to 0.250) demonstrated that 18° camber reduced times taken to perform the manoeuvrability drill compared with 15°. It was concluded that 18° camber was the best performing setting investigated given its superior performance for both linear and non-linear aspects of mobility, whereas 24° camber impaired linear performance. This was likely to be due to the greater drag forces experienced. Subsequently, athletes would be recommended to avoid 24° camber and young or inexperienced athletes in particular may benefit from selecting 18° as a starting point due to its favourable performance for all aspects of mobility performance in the current study.

Effects of abdominal binding on field-based exercise responses in Paralympic athletes with cervical spinal cord injury

UNLABELLED Abdominal binding has been shown to improve resting cardiorespiratory function in individuals with cervical SCI, but it is not yet clear whether this approach improves the exercise response. OBJECTIVES To determine the effects of abdominal binding on parameters relating to wheelchair sports performance in highly-trained athletes with cervical SCI. DESIGN Repeated-measures field-based study. METHODS Ten Paralympic wheelchair rugby players with motor-complete SCI (C5-C7) completed a series of exercise tests in two conditions (bound and unbound). The following parameters were assessed: agility and acceleration/deceleration performance; cardiorespiratory function and gross efficiency during submaximal wheelchair propulsion; anaerobic performance and propulsion kinematics during a 30s Wingate test; repeated sprint performance during a 10×20m test; and aerobic performance during a repeated 4min push test. RESULTS Compared to unbound, 6 of 17 field-based performance measures changed significantly with binding. Time to complete the acceleration/deceleration test decreased (p=0.005), whereas distances covered during the repeated 4min push test increased (p<0.043). Binding elicited significant reductions in minute ventilation during submaximal wheelchair propulsion (p=0.040) as well as blood lactate accumulation and limb discomfort during the second set of the repeated 4min push test (p=0.012 and 0.022). There were no statistically significant effects of binding on any other variable. CONCLUSIONS Abdominal binding improves some important measures of field-based performance in highly-trained athletes with cervical SCI. The changes may be attributable, at least in part, to improvements in trunk stability, ventilatory efficiency and/or haemodynamics.

Effect of team rank and player classification on activity profiles of elite wheelchair rugby players

Abstract The aim of the current study was to establish which indicators of mobility are associated with successful wheelchair rugby performance and determine whether these indicators differed across classification. Data were collected from 11 international teams during 30 matches (353 match observations) using a radio-frequency-based, indoor tracking system across two tournaments. Players (n = 111) were first grouped by team rank as determined by their International Wheelchair Rugby Federation (IWRF) world ranking (LOW, MID, HIGH) and then into one of four groups based on their IWRF classification: Group I (0.5), Group II (1.0–1.5), Group III (2.0–2.5) and Group IV (3.0–3.5). The volume of activity (relative distance and mean speed), peak speed and time spent within classification-specific arbitrary speed zones were calculated for each individual. Although no differences were identified in the volume of activity, playing time was significantly reduced in LOW (34:51 ± 8:35) compared to MID (48:54 ± 0:51) and HIGH (45:38 ± 9:53), which was further supported by the greater number of substitutions performed by LOW. HIGH achieved greater peak speeds (3.55 ± 0.40 m · sˉ1) than LOW (3.27 ± 0.42 m · sˉ1) and MID (3.45 ± 0.41 m · sˉ1). Peak speed was further shown to be classification-dependent (P ≤ 0.005), whereby HIGH Groups III and IV players achieved greater peak speeds than LOW and MID. The time spent performing high-intensity activities was also greater in HIGH compared to LOW and MID, whilst further influenced by classification (P ≤ 0.0005). To conclude, peak speed and the ability to perform a greater number of high-intensity activities were associated with successful performance in wheelchair rugby.

Effects of Wheel and Hand-rim Size on Submaximal Propulsion in Wheelchair Athletes

PURPOSE This study aimed to investigate the effects of fixed gear ratio wheel sizes on the physiological and biomechanical responses to submaximal wheelchair propulsion. METHODS Highly trained wheelchair basketball players (N = 13) propelled an adjustable sports wheelchair in three different wheel sizes (24, 25, and 26 inches) on a motor-driven treadmill. Each wheel was equipped with force-sensing hand-rims (SMARTWheel), which collected kinetic and temporal data. Oxygen uptake (V˙O2) and HR responses were measured with high-speed video footage collected to determine three-dimensional upper body joint kinematics. RESULTS Mean power output and work per cycle decreased progressively with increasing wheel size (P < 0.0005). Increasing wheel size also reduced the physiological demand with reductions in VO2 for 25-inch (0.90 ± 0.20 L · min(-1), P = 0.01) and 26-inch wheels (0.87 ± 0.16 L · min(-1), P = 0.001) compared with 24-inch wheels (0.98 ± 0.20 L · min(-1)). In addition, reductions in HR were observed for 26-inch wheels (99 ± 6 beats · min(-1)) compared with 25-inch (103 ± 8 beats · min(-1), P = 0.018) and 24-inch wheels (105 ± 9 beats · min(-1), P = 0.004). Mean resultant forces also decreased progressively with increasing wheel size (P < 0.0005). However, no changes in temporal or upper body joint kinematics existed between wheel sizes. CONCLUSIONS A greater power requirement owing to a greater rolling resistance in 24-inch wheels increased the physiological demand and magnitude of force application during submaximal wheelchair propulsion.

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.