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.
Barry S. Mason, James M. Rhodes and Victoria L. Goosey-Tolfrey
Marni J. Simpson, David G. Jenkins and Vincent G. Kelly
Limited research in court sports, such as handball 9 and basketball, 4 , 5 has identified the demands of specific training drills and SSG. Schelling and Torres 5 used inertial movement units (IMUs) to compare the accelerometer loads between various SSG drill formats in elite basketball. They reported
Rob Duffield, Alistair Murphy, Aaron Kellett and Machar Reid
To investigate the effects of combining cold-water immersion (CWI), full-body compression garments (CG), and sleep-hygiene recommendations on physical, physiological, and perceptual recovery after 2-a-day on-court training and match-play sessions.
In a crossover design, 8 highly trained tennis players completed 2 sessions of on-court tennis-drill training and match play, followed by a recovery or control condition. Recovery interventions included a mixture of 15 min CWI, 3 h of wearing full-body CG, and following sleep-hygiene recommendations that night, while the control condition involved postsession stretching and no regulation of sleeping patterns. Technical performance (stroke and error rates), physical performance (accelerometry, countermovement jump [CMJ]), physiological (heart rate, blood lactate), and perceptual (mood, exertion, and soreness) measures were recorded from each on-court session, along with sleep quantity each night.
While stroke and error rates did not differ in the drill session (P > .05, d < 0.20), large effects were evident for increased time in play and stroke rate in match play after the recovery interventions (P > .05, d > 0.90). Although accelerometry values did not differ between conditions (P > .05, d < 0.20), CMJ tended to be improved before match play with recovery (P > .05, d = 0.90). Furthermore, CWI and CG resulted in faster postsession reductions in heart rate and lactate and reduced perceived soreness (P > .05, d > 1.00). In addition, sleep-hygiene recommendations increased sleep quantity (P > .05, d > 2.00) and maintained lower perceived soreness and fatigue (P < .05, d > 2.00).
Mixed-method recovery interventions (CWI and CG) used after tennis sessions increased ensuing time in play and lower-body power and reduced perceived soreness. Furthermore, sleep-hygiene recommendations helped reduce perceived soreness.
Lucas A. Pereira, Andrew A. Flatt, Rodrigo Ramirez-Campillo, Irineu Loturco and Fabio Y. Nakamura
To compare the LnRMSSD and the LnRMSSD:RR values obtained during a 5-min stabilization period with the subsequent 5-min criterion period and to determine the time course for LnRMSSD and LnRMSSD:RR stabilization at 1-min analysis in elite team-sport athletes.
35 elite futsal players (23.9 ± 4.5 y, 174.2 ± 4.0 cm, 74.0 ± 7.5 kg, 1576.2 ± 396.3 m in the Yo-Yo test level 1).
The RR-interval recordings were obtained using a portable heart-rate monitor continuously for 10 min in the seated position. The 2 dependent variables analyzed were LnRMSSD and LnRMSSD:RR. To calculate the magnitude of the differences between time periods, effect-size (ES) analysis was conducted. To assess the levels of agreement, intraclass correlation coefficients (ICC) and Bland-Altman plots were used.
The LnRMSSD and LnRMSSD:RR values obtained during the stabilization period (0–5 min) presented very large to nearly perfect ICCs with the values obtained during the criterion period (5–10 min), with trivial ESs. In the ultra-short-term analysis (ie, 1-min segments) the data showed slightly less accurate results, but only trivial to small differences with very large to nearly perfect ICCs were found.
LnRMSSD and LnRMSSD:RR can be recorded in 5 min without traditional stabilization periods under resting conditions in team-sport athletes. The ultra-short-term analysis (1 min) also revealed acceptable levels of agreement with the criterion.
Marni J. Simpson, David G. Jenkins, Aaron T. Scanlan and Vincent G. Kelly
Purpose: To examine relationships between external- and internal-workload variables in an elite female netball team, with consideration of positional differences. Methods: Nine elite female netball athletes had their weekly workloads monitored across their preseason and competition phases of a season. Internal workload was determined using summated heart-rate (HR) zones and session ratings of perceived exertion (sRPE), whereas external workload was determined using inertial movement units and included absolute PlayerLoad (PL), relative PL (PL per minute), accelerations (ACCEL), decelerations (DECEL), jumps, changes of direction (COD), high-intensity events, medium-intensity events, low-intensity events, PL in the forward direction, PL in the sideways direction, and PL in the vertical direction. Relationships between external- and internal-workload variables in the team and relative to playing position were examined. Results: Across the team, the strongest external workloads that correlated with summated HR zones were PL (r = .65), COD (r = .64), ACCEL (r = .61), and DECEL (r = .61). The strongest external workloads that correlated with sRPE were COD (r = .79), followed by jumps (r = .76), ACCEL (r = .75), and DECEL (r = .75). For all positions, except-goal shooter, the strongest correlation was between PL and sRPE (r = .88–.94). In the goal-shooter position, the strongest correlation was between summated HR zones and DECEL (r = .89). Conclusions: The inertial movement unit-derived external-workload variables are strongly related to common internal-workload variables. In particular, COD and sRPE appear to provide a good monitoring combination of external and internal training loads for elite netball players.
Robert G. Lockie, Matthew D. Jeffriess, Tye S. McGann, Samuel J. Callaghan and Adrian B. Schultz
Research indicates that planned and reactive agility are different athletic skills. These skills have not been adequately assessed in male basketball players.
To define whether 10-m-sprint performance and planned and reactive agility measured by the Y-shaped agility test can discriminate between semiprofessional and amateur basketball players.
Ten semiprofessional and 10 amateur basketball players completed 10-m sprints and planned- and reactive-agility tests. The Y-shaped agility test involved subjects sprinting 5 m through a trigger timing gate, followed by a 45° cut and 5-m sprint to the left or right through a target gate. In the planned condition, subjects knew the cut direction. For reactive trials, subjects visually scanned to find the illuminated gate. A 1-way analysis of variance (P < .05) determined between-groups differences. Data were pooled (N = 20) for a correlation analysis (P < .05).
The reactive tests differentiated between the groups; semiprofessional players were 6% faster for the reactive left (P = .036) and right (P = .029) cuts. The strongest correlations were between the 10-m sprints and planned-agility tests (r = .590–.860). The reactive left cut did not correlate with the planned tests. The reactive right cut moderately correlated with the 10-m sprint and planned right cut (r = .487–.485).
The results reemphasized that planned and reactive agility are separate physical qualities. Reactive agility discriminated between the semiprofessional and amateur basketball players; planned agility did not. To distinguish between male basketball players of different ability levels, agility tests should include a perceptual and decision-making component.
Mario A. Lafortune
Miniature pressure sensors and high-speed video were used to assess the lateral support and stability of court footwear during in vivo performance of lateral side-stepping moves. Two distinct types of court footwear construction were evaluated and were found to differ by approximately 100% and 200% in lateral support and stability, respectively. The heel control index that combined both parameters revealed differences exceeding 425%. A comparison of shoes that differed only in one construction feature produced similar trends. These overall results suggest that the combined high-speed video/pressure approach allows high discrimination of footwear rearfoot control properties during in vivo simulated playing conditions. The specific experimental results suggest that footwear designed for court sports exhibits considerable differences in foot support and stability. Furthermore, it was found that some construction features could improve these properties in court footwear.
Katy E. Griggs, Christof A. Leicht, Michael J. Price and Victoria L. Goosey-Tolfrey
Individuals with a spinal-cord injury have impaired thermoregulatory control due to a loss of sudomotor and vasomotor effectors below the lesion level. Thus, individuals with high-level lesions (tetraplegia) possess greater thermoregulatory impairment than individuals with lower-level lesions (paraplegia). Previous research has not reflected the intermittent nature and modality of wheelchair court sports or replicated typical environmental temperatures. Hence, the purpose of this study was to investigate the thermoregulatory responses of athletes with tetraplegia and paraplegia during an intermittent-sprint protocol (ISP) and recovery in cool conditions.
Sixteen wheelchair athletes, 8 with tetraplegia (TP, body mass 65.2 ± 4.4 kg) and 8 with paraplegia (body mass 68.1 ± 12.3 kg), completed a 60-min ISP in 20.6°C ± 0.1°C, 39.6% ± 0.8% relative humidity on a wheelchair ergometer, followed by 15 min of passive recovery. Core temperature (T core) and mean (T sk) and individual skin temperatures were measured throughout.
Similar external work (P = .70, ES = 0.20) yet a greater T core (P < .05, ES = 2.27) and T sk (P < .05, ES = 1.50) response was demonstrated by TP during the ISP.
Despite similar external work, a marked increase in Tcore in TP during exercise and recovery signifies that thermoregulatory differences between the groups were predominantly due to differences in heat loss. Further increases in thermal strain were not prevented by the active and passive recovery between maximal-effort bouts of the ISP, as T core continually increased throughout the protocol in TP.
-0191 Validity and Reliability of an Inertial Sensor for Wheelchair Court Sports Performance Barry S. Mason * James M. Rhodes * Victoria L. Goosey-Tolfrey * 4 2014 30 2 326 331 10.1123/jab.2013-0148 Using a Discrete Preisach Model for Hysteresis in Ankle Joint Passive Moment Ching-Chao Chan * Chou
Annemarie M.H. de Witte, Monique A.M. Berger, Marco J.M. Hoozemans, Dirkjan H.E.J. Veeger and Lucas H.V. van der Woude
adjustments of the wheelchair mechanics of interfacing. The effects of manipulating wheelchair configurations, on aspects of mobility performance during wheelchair court sports, have received limited attention in scientific research. In the past, some studies investigated seat height parameters within the