Performance and physiological characterisation analysis involving

In addition to the associated topics discussed in section 2.1.1 through to section 2.2.3; other characterisation studies are available which have specifically analysed wheelchair athletes performance related to game dynamics and which have correlated the results and methods with biomechanics analysis and wheelchair configuration.

• Sprinting performance: The ability to sprint is highly regarded in all wheelchair sports. In wheelchair racing is required both for long-distance races e.g. change in pace, sprint start/finish as well as the speed required completing shorter distances as fast as possible [65]. For basketball, rugby and tennis as they are multiple-sprint based wheelchair sports, the player’s ability to accelerate from a standstill is considered most important. For these athletes testing speeds over 20m is often irrelevant [65]. In relation to the sprinting performance of court-based wheelchair sports athletes, a study by Coutts, utilized the mathematical relationships of drag force and power loss [49] to report the findings of measurements of the wheelchair drag and maximal sprint performance abilities of nine male and eight female wheelchair basketball players. Results of Coutts’ study are reproduced in table below as a representation of the maximal sprint performance and power outcome of athletes participating in court based wheelchair sports.

Table 2.2 Sprint performance of wheelchair basketball players. Reproduced from Coutts [48].

Coast-down trials were performed at speeds between 1-1.5 m/s) to maximal (4.5 m/s) over six trials for determining wheelchair drag and then, maximal sprint trials were performed from a stationary start over the length (35 m) of the gymnasium floor. Drag force during the coast-down trials and the power output during the sprint trials were determined and compared across gender. Coutts reported no significant differences between the means of the male and female groups in age (27 vs. 28 yrs), wheelchair mass (12 .0 vs. 11 .61 kg), or regression predicted drag forces at speeds of 2 m/s (5.3 vs. 5.5 N) and 5 m/s (16.7 vs. 13.5 N). Male subjects were heavier (78.3 vs. 59.1 kg) and maintained a higher tire pressure (123 vs. 94 psi). In the sprint trial results, the males exhibited a significantly higher maximal speed (4 .75 vs. 4.08 m/s), higher peak

acceleration (1.32 vs. 1.03 m/s2), and a higher peak power output (530 vs. 264 w) [48].

• Propulsion kinetics: Goosey-Tolfrey et. al investigated propulsion kinetics of six wheelchair racers at two different speeds, 4.70m/s and 5.64 m/s, on a wheelchair ergometer. The study assessed the change in propulsion kinetics with an increase in speed. The hypothesis tested was that propulsive force would increase in proportion to speed, to accommodate the additional work required. Data was collected using eight pairs (16 in total) of strain gauges, mounted on four bars attached to the hand-rim of a racing wheelchair wheel, which measured the medio-lateral and tangential forces applied to the hand- rim. A single on-line (ELITE) infrared camera operating at 100 Hz was also positioned perpendicular to the wheelchair ergometer to record the location of the hand with respect to the hand-rim [66]. This study showed that peak tangential force occurred when the hand was positioned on the hand-rim between 140 and 180°. The hypothesis was verified with the peak handrim forces applied tangentially increasing from 132 to 158N and those applied medio-laterally increased from 90 to 104N with the increase in system’s speed. The ratio of tangential to total measured force was 80% at the speed of 4.70m/s, which is a comparable speed to court-based wheelchair athletes. It was concluded that wheelchair racers adopt a different propulsion strategy than that employed in everyday chairs and that the forces increase in proportion to propulsion speed [66]. There was no specific data found for the case of court-based sports, however, propulsion technique patterns and differences in force application at maximal effort can be expected with

increase in speed during sprinting performance for court-based athletes as well [55, 56].

• Physiological testing with disabled athletes: A set of guidelines for physiological testing with disabled athletes has been developed by Goosey- Tolfrey to implement safe and effective testing procedures for the disabled athlete and assist with the challenges presented by testing with athletes displaying many different types of disability and classifications (e.g. cerebral palsy or spinal cord injuries (SCI)) [65]. According to these guidelines, important points to consider for testing protocols in this investigation are related to:

- Pre-test considerations to avoid compromising testing results such as bladder issues, unusual spasticity or autonomic dysreflexia [65].

- Chair transfer environment to avoid fractures, and hazards [65].

- Minimal clothing for testing, ensure sufficient strapping for trunk and lower extremities stability. Always record chair configurations and strapping details [65].

- Ensure suitable globes, and regular operating conditions of propulsion such as use of glue on handrim is present.

- Cease exercise that aggravates chronic shoulder joint pain as overuse injuries are common to wheelchair users [65].

- Ensure a ventilated environment and a thermally neutral environment as the majority of participants with SCI have impaired thermoregulatory capacity. Ensure that the physiology laboratory has air-conditioning to perform testing [65].

- A variety of exercise testing modes can be used for the physiological assessment of the disabled athlete. Adapt equipment as needed based on testing considerations. The main advantage of wheelchair exercise is its specificity for wheelchair users, especially if the athlete’ sporting wheelchair is used. However, a main disadvantage of wheelchair ergometry is that mechanical efficiency is lower, because of increased energy expenditure arising from isometric muscle activity required to stabilise the trunk during the application of force to the hand-rim [65]. - If a wheelchair ergometer (werg) is used, record the braking force.

This is used to adjust the rolling resistance of the rear wheels on the rollers. The braking force is provided principally by the weight of the participant and their wheelchair [65].

- Guidance for werg speed ranges (uk athletes) [65]: -Wheelchair racers (mixed) – 2.7 to 7.5 m.s−1 (0.9 m.s−1 increments) -Male wheelchair basketball – 1.5 to 3.8 m.s−2 (0.2–0.4 m.s−1 increments) -Female wheelchair tennis – 0.9 to 1.8 m.s−1 (0.2 m.s−1 increments)

-Male wheelchair tennis (open class) – 1.2 to 3.0m.s−1(0.2 m.s−1 increments)

-Male wheelchair tennis (quadriplegic class) – 1.0 to 2.4 m.s−1 (0.2 m.s−1increments).

- Maximal effort on an ergometer: To satisfy the muscle force-velocity relationships an optimal braking load is required. However, no optima have been agreed. Protocols with limited resistance create a ceiling for achievable PPO rather than muscular function. Hence, some researchers have kept wheeling speed to 3 m.s−1, to avoid difficulties in propulsion technique [65].

Field-based testing: Since laboratory tests require the use of specialised and expensive equipment that is not accessible to every one, efforts have been made to develop appropriate field tests [65].

2.1.5 Dynamic wheelchair performance models following straight and