Physiological demands and court-movement patterns of wheelchair tennis

The wheelchair tennis evidence base has developed considerably in recent years. For those with a spinal cord injury (SCI), or severe physical impairment, tennis participation represents an opportunity for skill and motor development, and potential for disease risk reduction (Abel et al., 2008). However, as a complex series of technical, tactical and physical elements are implicated, participation for novice, developmental or low-skill players can be challenging. Hence, extension of the evidence base to consider the responses of such groups during play is of considerable value. Initial experimental studies in this thesis investigated the validity, reliability and applicability of instrumentation for the assessment of wheelchair tennis court-movement. Comparisons were made between a global positioning system (GPS) and the data logger (DL) device (Study 1). GPS underestimated criterion distance in tennis-specific drills and reported lower match-play values than the DL. In contrast, DL placed on the outside wheel offered an accurate representation of distance. However, underestimations for DL were revealed at speeds > 2.50 m·s-1 during treadmill testing. Consequently, Study 2 extended this work with consideration of DL applicability for wheelchair tennis match-play. Examination of speed profiles revealed that time spent below the threshold for accuracy was trivial, confirming DL applicability for court-movement assessment. Further between-group comparisons for rank [highly-ranked (HIGH), low-ranked (LOW)], sex (male, female) and format (singles, doubles) revealed that LOW were stationary for longer than HIGH and spent more time at low propulsion speeds. Time in higher speed zones was greatest for HIGH and doubles players. Between-group differences (rank) were further scrutinised in Study 3 with attention paid to describing the physiological response of competitive match-play aligned to court-movement. Set outcome (result) was also examined. Independent of result, HIGH covered greater overall, forwards, reverse and forwards-to-reverse distances than LOW. Interestingly, HIGH winners covered greater distances than HIGH losers and had a higher mean average and minimum heart rate (HR) than LOW winners. In contrast, LOW losers had a higher mean average and mean minimum HR than LOW winners. Collectively, these outcomes suggest an enhanced ability for HIGH to respond to ball movement and the physiological and skill challenges of match-play. While this thesis confirmed that the activity duration and playing intensity is sufficient to confer health-related effects (Study 3), differences identified for rank suggested that strategies to 4 enable performance improvements in LOW were merited. The International Tennis Federation (ITF) has suggested that all starter players should be able to serve, rally and score from their first lesson (ITF, 2007). The reality however, is that chair propulsion whilst holding a racket is complex, and therefore, tennis play is challenging for novice and developmental players. Hence, the remainder of experimental work focused on interventions to enable increased court-movement and development of wheelchair tennis-specific court-mobility for LOW. The ITF have endorsed the use of a low-compression ball (LCB) for novices. An LCB bounces lower and moves more slowly through the air than a standard-compression ball (SCB). Novel findings from Study 4 revealed that greater total and forwards distances, greater average speeds and less time stationary result from use of the LCB. Increased movement activity occurred without associated increases in physiological cost, but was considered advantageous, with players adopting stronger positions for shot-play. Further examination of the linkage between movement and physiological variables were explored in the final experimental investigation (Study 5). A short period of organised practice enabled higher overall and forwards distances, and peak and average speeds to be achieved during match-play, without associated increases in physiological cost. Changes were desirable and represented enhanced court-mobility and mechanical efficiency (ME). Wheelchair tennis players were also more self-confident in tennis-specific chair-mobility, post-practice. The racket was a constraint, with lower distances and speeds, and a lower peak physiological response, achieved during tennis practice completed with a racket. This thesis advocates the use of an LCB and a short period of pre-match court-mobility practice for the novice wheelchair tennis player. Collectively, these interventions are likely to prompt greater court-movement enabling better court-positioning, develop confidence in court-mobility and shot-play, develop competence in racket handling whilst pushing, and enhancing ME. These characteristics are likely to enable participation with the likely inference being that greater competence, skill and self-confidence promotes greater enjoyment and therefore enhances longer-term compliance. This is of considerable practical significance given that tennis typically attracts new players to the game, but is less successful at retaining them (ITF, 2007)