Practice improves court mobility and self-efficacy in tennis-specific wheelchair propulsion

PURPOSE

Wheelchair tennis (WT) propulsion is uniquely characterized by the requirement for racket holding coupled with effective hand-rim contact. Thus, investigations involving strategies to enhance chair mobility skills are merited. The aim was to examine the effects of organized practice on WT match play responses and the impact of racket holding during practice.

MATERIALS AND METHODS

Following physiological profiling involving graded and peak exercise testing, 16 able-bodied (AB) participants performed bouts of WT match play interspersed with practice involving wheelchair mobility drills completed with (R) or without (NR) a tennis racket. A data logger recorded distance and speed. Self-efficacy was reported.

RESULTS AND CONCLUSIONS

Significant main effects for match revealed higher post-practice overall and forwards distances (p < 0.05), peak (p < 0.005) and average (p < 0.05) speeds and self-efficacy (SE) (p = 0.001) were attained. During practice, lower distances and speeds were achieved with R, with a lower physiological cost than NR. Practice increases court movement and SE with no associated increases in physiological cost. Changes represent enhanced court mobility. Differences between practice characteristics provide options for skill development and optimization of health outcomes.IMPLICATIONS FOR REHABILITATIONWheelchair tennis participation is likely to confer positive health effects in those with a disability or physical impairment.As chair propulsion combined with racket holding represents a complex skill challenge, novices may find the sport challenging to play.Tennis-specific mobility drills improve confidence and chair propulsion skill with likely crossover into tennis match play competence and ability.

The physiological and biomechanical effects of forwards and reverse sports wheelchair propulsion

OBJECTIVE

To explore the physiological and biomechanical differences between forwards (FOR) and reverse (REV) sports wheelchair propulsion.

DESIGN

Fourteen able-bodied males with previous wheelchair propulsion experience pushed a sports wheelchair on a single-roller ergometer in a FOR and REV direction at three sub-maximal speeds (4, 6, and 8 km/hour). Each trial lasted 3 minutes, and during the final minute physiological and biomechanical measures was collected.

RESULTS

The physiological results revealed that oxygen uptake (1.51 ± 0.29 vs. 1.38 ± 0.26 L/minute, P = 0.005) and heart rate (121 ± 19 vs. 109 ± 14 beats/minute, P < 0.0005) were significantly greater during REV than FOR only during the 8 km/hour trials. From a biomechanical perspective, push frequencies were similar between FOR and REV across all speeds (P > 0.05). However, greater mean resultant forces were applied during FOR (P < 0.0005) at 4 km/hour (66.7 ± 19.5 vs. 49.2 ± 10.3 N), 6 km/hour (90.7 ± 21.9 vs. 65.3 ± 18.6 N), and 8 km/hour (102.5 ± 17.6 vs. 68.7 ± 13.5 N) compared to REV. Alternatively, push times and push angles were significantly lower (P ≤ 0.001) during FOR at each speed.

CONCLUSIONS

The current study demonstrated that at higher speeds physiological demand becomes elevated during REV. This was likely to be associated with an inability to apply sufficient force to the wheels, thus requiring kinematic adaptations in order to maintain constant speeds in REV.

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 vs. standard compression tennis balls. Eleven wheelchair basketball players were monitored during repeated bouts of tennis (20 min) 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), forward 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 1-1.49 (P<0.05), 1.5-1.99 (P<0.05) and 2.0-2.49 (P<0.05) m ∙ sec(-1) when using the low-compression ball. Main effects for physiological variables were not significant. Greater total and forward distance, and higher average speeds are achieved using a low-compression ball. The absence of any difference in measured HR and estimated physiological responses would indicate 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.

Criterion validity and accuracy of global positioning satellite and data logging devices for wheelchair tennis court movement

PURPOSE

To compare the criterion validity and accuracy of a 1 Hz non-differential global positioning system (GPS) and data logger device (DL) for the measurement of wheelchair tennis court movement variables.

METHODS

Initial validation of the DL device was performed. GPS and DL were fitted to the wheelchair and used to record distance (m) and speed (m/second) during (a) tennis field (b) linear track, and (c) match-play test scenarios. Fifteen participants were monitored at the Wheelchair British Tennis Open.

RESULTS

Data logging validation showed underestimations for distance in right (DLR) and left (DLL) logging devices at speeds >2.5 m/second. In tennis-field tests, GPS underestimated distance in five drills. DLL was lower than both (a) criterion and (b) DLR in drills moving forward. Reversing drill direction showed that DLR was lower than (a) criterion and (b) DLL. GPS values for distance and average speed for match play were significantly lower than equivalent values obtained by DL (distance: 2816 (844) vs. 3952 (1109) m, P = 0.0001; average speed: 0.7 (0.2) vs. 1.0 (0.2) m/second, P = 0.0001). Higher peak speeds were observed in DL (3.4 (0.4) vs. 3.1 (0.5) m/second, P = 0.004) during tennis match play.

CONCLUSIONS

Sampling frequencies of 1 Hz are too low to accurately measure distance and speed during wheelchair tennis. GPS units with a higher sampling rate should be advocated in further studies. Modifications to existing DL devices may be required to increase measurement precision. Further research into the validity of movement devices during match play will further inform the demands and movement patterns associated with wheelchair tennis.

Hand-rim forces and gross mechanical efficiency at various frequencies of wheelchair propulsion

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 ms(-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.

Influence of varied tempo music on wheelchair mechanical efficiency following 3-week practice

The purpose of this study was to analyse adaptations in propulsion technique and gross efficiency in novice able-bodied subjects during the initial phase of learning hand-rim wheelchair propulsion to music. 22 able bodied participants performed wheelchair propulsion (1.1 m·s(-1)) followed by a VO(2) peak test on a wheelchair ergometer. Push frequency, gross efficiency (GE), heart rate, rating of perceived exertion and propulsion technique variables (force application and temporal characteristics) were recorded. Participants were then assigned to a 3-wk practice period listening to i) 125 beats·min(-1) tempo music (LOW); ii) 170 beats·min(-1) tempo music (HIGH); or iii) a control group (CON). Following practice, all participants repeated the pre-testing protocol whilst force application data was collected in practice trials 1 and 9. After accounting for the pre-practice differences in GE (using ANCOVA), GE was higher in LOW compared with CON (P=0.038; 6.6 vs. 6.1% respectively). The differences between CON vs. HIGH and LOW vs. HIGH (P=0.830; P=0.188) were trivial suggesting that only LOW experienced an increase in GE. Practice had a favourable effect on the perceptions of effort, work per cycle, push and cycle time in contrast to the CON group. The use of music in a rehabilitation setting warrants further investigation.

Wheelchair propulsion: effects of experience and push strategy on efficiency and perceived exertion

The purpose of this study was to examine the role of wheeling experience on efficiency, metabolic cost, and differentiated ratings of perceived exertion (RPEs) during synchronous and asynchronous hand-rim propulsion with varying arm frequencies. Fourteen able-bodied (AB) male participants and 8 male wheelchair sportsmen (WS) performed tests of peak oxygen consumption for both propulsion modes. Subsequently, 2 series of five 4-min sub-maximal exercise bouts were completed at an individualized velocity (60% of peak oxygen consumption). Arm frequencies consisted of the freely chosen frequency (FCF), followed by 4 counter-balanced paced trials pushing at 60%, 80%, 120%, and 140% of the FCF. Efficiency indices (gross, GE; work, WE) were determined and peripheral (RPE-P), central (RPE-C), and overall (RPE-O) RPEs were recorded. The GE (6.4% vs. 8.4%) and WE (11.3% vs. 15.1%) were significantly higher in WS than in AB (p = 0.001). Trends in the oxygen consumption, GE, and WE data were similar in both groups, propulsion mode, and arm frequency. Data suggest that 80% FCF resulted in improved efficiency for both propulsion mode and group, although the differences between those arm frequencies immediately above and below were non-significant. Lower RPE scores corresponded with higher efficiency values. Regardless of group there were significant differences (p = 0.001) between the differentiated RPE measures, whereby RPE-P was on average always the highest score (13.1) and RPE-C the lowest (11.1; RPE-O was 12.2). In conclusion, despite the anticipated differences in efficiency between the WS and AB participants, this study confirmed that psycho-physiological measures produce similar trends to physiological measures with manipulations of both arm frequency and propulsion mode.

Efficiency of Wheelchair Propulsion and Effects of Strategy

The purpose of this study was to determine the contributions of arm frequency and propulsion mode on the internal work during submaximal wheelchair propulsion. Twelve able-bodied participants performed a V.O (2) peak test on a wheelchair ergometer. On a separate occasion, six (4 min) submaximal exercise conditions employing two modes of propulsion (synchronous, SYN vs. asynchronous, ASY) at arm frequencies of 40 and 80 rev . min (-1) were performed at 1.2 m . s (-1) and 1.7 m . s (-1). These conditions resulted in three push strategy combinations (ASY [20 : 20], SYN [40 : 40] & ASY [40 : 40]) at two speeds. Gross, net, work and delta efficiency were determined. The cost of unloaded exercise was significantly lower for the ASY [20 : 20] than both ASY and SYN [40 : 40] (0.49 vs. 0.58 and 0.57 L . min (-1), respectively). All the efficiency indices decreased as velocity increased (p < 0.01). ASY [20 : 20] was the least efficient (gross and work) mode (4.2 +/- 0.4 % and 6.2 +/- 0.8 % respectively). Comparison of equal arm frequencies (ASY [40 : 40] vs. SYN [40 : 40]); found the efficiency to be lower for ASY propulsion (p < 0.05). Under the current testing conditions SYN propulsion mode offers greater efficiency during wheelchair propulsion.

A comparison between intermittent and constant wheelchair propulsion strategies

The purpose of this study was to investigate the effect of different synchronous push strategies on physiological parameters and temporal timing characteristics. Eight novice male able-bodied participants completed four counter-balanced conditions: two push strategies (constant pushing) and intermittent pushing (INT) at two push frequencies (40 and 70 pushes/min) at 27 W. The ANOVA main effects for frequency indicated that regardless of push strategy, oxygen cost and mechanical efficiency increased with an increase in push frequency (p < 0.01). The INT40 strategy resulted in the lowest heart rate (115 +/- 19 beats/min). With increased frequency the push angle was reduced (91 degrees vs. 78 degrees respectively) and the push was initiated at a more anterior position of the wheel (p < 0.05). The results suggest that regardless of push strategy, the over-riding factor that influences both the physiological and timing parameters measured was push frequency.