Effect of low-compression balls on wheelchair tennis match-play

The purpose of this study was to compare court-movement variables and physiological responses to wheelchair tennis match-play when using low versus standard compression tennis balls. Eleven wheelchair basketball players were monitored during repeated bouts of tennis (20-minutes) using both ball types. Graded and peak exercise tests were completed. For match-play, a data logger was used to record distance and speed. Individual linear heart rate oxygen consumption relationships were used to estimate match-play oxygen uptake. Significant main effects for ball type revealed that total distance (P<0.05), forwards distance (P<0.05), and average speed (P<0.05) were higher for play using a low compression ball. A lower percentage of total time was spent stationary (P<0.001), with significantly more time spent at speeds of 1 to 1.49 (P<0.05), 1.5 to 1.99 (P<0.05) and 2.0 to 2.49 (P<0.05) m∙sec-1 when using the low compression ball. Main effects for physiological variables were not significant. Greater total and forwards distance, and higher average speeds are achieved using a low compression ball. No difference in measured HR and estimated physiological responses indicates that players move further and faster at no additional mean physiological cost. This type of ball will be useful for novice players in the early phases of skill development

Acute effects of breaking up prolonged sedentary time on cardiovascular disease risk markers in adults with paraplegia

© 2020 The Authors. Elevated levels of cardiovascular disease (CVD) risk markers are highly prevalent in people with a spinal cord injury (SCI). Breaking up prolonged sedentary time with short, regular bouts of physical activity can reduce postprandial glucose and lipid levels in able-bodied individuals. The effects in people with paraplegia are unknown. The study aims were to examine the acute postprandial glucose (primary aim), lipid, blood pressure, and psychological responses (secondary aims) to breaking up prolonged sedentary time in individuals with paraplegia. This was a randomized crossover design trial. Fourteen participants with paraplegia (age 51 ± 9 years, trunk fat mass 44.3 ± 7.7%) took part in the following two, 5.5-hour conditions: (1) uninterrupted sedentary time (SED), and (2) sedentary time interrupted with 2 minutes of moderate-intensity arm crank ergometer physical activity every 20 minutes (SED-ACT). Standardized breakfast and lunch test meals were consumed during each condition. The outcomes were compared between conditions using linear mixed models. Glucose area under the curve (AUC) was significantly lower during the lunch postprandial period in SED-ACT vs SED (incremental AUC 1.9 [95% CI 1.0, 2.7) and 3.0 [2.1, 3.9] mmol/L∙2.5 hour, respectively, P = .015, f = 0.34). There were no differences between conditions for the breakfast or total 5.5 hours postprandial periods (P > .05). Positive affect was higher in SED-ACT than SED (P = .001). Breaking up prolonged sedentary time acutely attenuates lunch postprandial glucose and improves positive affect in people with paraplegia. This may have clinical relevance for reducing CVD risk and improving psychological well-being in this population.Heart Research UK. Grant Number: RG2655/17/1

Cooling athletes with a spinal cord injury

Cooling strategies that help prevent a reduction in exercise capacity whilst exercising in the heat have received considerable research interest over the past 3 decades, especially in the lead up to a relatively hot Olympic and Paralympic Games. Progressing into the next Olympic/Paralympic cycle, the host, Rio de Janeiro, could again present an environmental challenge for competing athletes. Despite the interest and vast array of research into cooling strategies for the able-bodied athlete, less is known regarding the application of these cooling strategies in the thermoregulatory impaired spinal cord injured (SCI) athletic population. Individuals with a spinal cord injury (SCI) have a reduced afferent input to the thermoregulatory centre and a loss of both sweating capacity and vasomotor control below the level of the spinal cord lesion. The magnitude of this thermoregulatory impairment is proportional to the level of the lesion. For instance, individuals with high-level lesions (tetraplegia) are at a greater risk of heat illness than individuals with lower-level lesions (paraplegia) at a given exercise intensity. Therefore, cooling strategies may be highly beneficial in this population group, even in moderate ambient conditions (~21 °C). This review was undertaken to examine the scientific literature that addresses the application of cooling strategies in individuals with an SCI. Each method is discussed in regards to the practical issues associated with the method and the potential underlying mechanism. For instance, site-specific cooling would be more suitable for an athlete with an SCI than whole body water immersion, due to the practical difficulties of administering this method in this population group. From the studies reviewed, wearing an ice vest during intermittent sprint exercise has been shown to decrease thermal strain and improve performance. These garments have also been shown to be effective during exercise in the able-bodied. Drawing on additional findings from the able-bodied literature, the combination of methods used prior to and during exercise and/or during rest periods/half-time may increase the effectiveness of a strategy. However, due to the paucity of research involving athletes with an SCI, it is difficult to establish an optimal cooling strategy. Future studies are needed to ensure that research outcomes can be translated into meaningful performance enhancements by investigating cooling strategies under the constraints of actual competition. Cooling strategies that meet the demands of intermittent wheelchair sports need to be identified, with particular attention to the logistics of the sport

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

Investigation of the potential for sonar detection in bubbly environments

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

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

Hand-rim Forces and Gross Mechanical Efficiency at Various Frequencies of Wheelchair Propulsion

<p>To determine the effects of push frequency changes on force application, fraction of effective force (FEF) and gross efficiency (GE) during hand-rim propulsion. 8 male able-bodied participants performed five 4-min sub-maximal exercise bouts at 1.8 m.s(-1); the freely chosen frequency (FCF), followed by 4 counter-balanced trials at 60, 80, 120 and 140 % FCF. Kinetic data was obtained using a SMART(Wheel), measuring forces and moments. The GE was determined as the ratio of external work done and the total energy expended. Increased push frequency led to reductions in peak resultant force (P <0.05), ranging from 167 to 117 N and peak tangential force (P <0.05), ranging from 117 to 77 N. However, FEF only demonstrated a significant difference between 60 % and 140 % FCF (69 +/- 9 % and 63 +/- 7, respectively; P <0.05). Work per cycle decreased significantly (P <0.05) and rate of force development increased significantly (P <0.05) with increased push frequency. GE values were significantly lower at 60 %, 120 % and 140 % FCF than 80 % and 100 % FCF (P <0.05). No meaningful associations were present between FEF and GE. Under the current testing conditions, changes in push frequency are accompanied with changes in the absolute force values, albeit without changes in either the gross pattern/trend of force application or FEF. Changes in GE are not explained by different levels of force effectiveness.</p>