Assessing the benefits of specificity on wheelchair athletes
Part two of this article looks at the exercise selection and results of the nine week training programme
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The training programme was designed to improve performance in wheelchair sprinting and to develop muscle balance by strengthening the upper body musculature and posterior shoulder groups. Disabled athletes tend to have imbalances in muscle groups (Horvat & Aufsesser, 1991). For example, individuals involved in wheelchair propulsion tend to have strong anterior shoulder muscles as a result of the action of pushing (Laskowski, 1994). This was clearly evident in the male subject, whose incline shoulder press (which primarily involves anterior deltoid) was as strong as his bench press (which primarily involves pectoris major). Therefore exercises involving trapezius, serratus anterior, levator scapulae, rhomboids, latissimus dorsi and the posterior aspect of the deltoids were included in the programme. Analysis of biomechanical needs of wheelchair racing identified pectoris major, anterior deltoids and triceps as the major gross musculature involved in wheelchair propulsion.
Injury prevention was partly achieved by developing muscle balance. The repetitive action of pushing with the arm and hand predisposes wheelchair athletes to repetitive strain syndromes such as inflammation of the shoulder external rotators and lateral and medial epicondylitis (Figoni, Morse & Hedrick, 1993). Therefore exercise selection included exercises for the shoulder rotator cuff, lateral and medial epicondyle, extensor carpi radialis brevis, extensor digatorum commanis, carpi radialis longus and extensor carpi ulnaris. This conditioning intervention was particularly warranted as both subjects experienced mild lateral epicondylitis during the training programme.
Also considered during the process of exercise selection was the role that postural and stabilising muscles would perform. This was deemed particularly important for the male subject as the absence of his sacrum caused him problems with balance and producing maximal forces. Therefore exercises were included for the abdominals and spinal erectus.
Finally, as the female subject had partial control of her hip flexors and leg adductors it was decided that these muscles should also be trained. The purpose here was to help develop stability, control of the chair and also to improve venous return through improved peripheral 'muscle pump'. Davis et al., (1990) have shown that stroke volume and cardiac output is increased when paraplegic subjects underwent functional neural muscular stimulation during arm-crank ergometry and this improvement was attributed to enhanced venous return.Results
The results showed that both subjects had considerable improvement in all the measured indices. The male subject gained 1.3 kg in body weight, yet his skinfold measurements were lower following the training period. The female subject lost 1.0 kg. in body weight and her skinfold measurements were also lower following the training period. The male subject increased his peak power output from 142W to 157W, the female from 153 W to 190 W. The male subject had a lower peak power output than the female (157 W versus 190 W) yet his mean power output was higher (148 W versus 123 W). The male subject improved his mean power output by 29W, the female subject by 35 W. On the muscular endurance tests the male subject had considerable improvement on his 6 RM bench press (+12.5 kg), 6 RM pull downs (+4 kg) and dips RM (+19). The female also improved on the muscular endurance tests by +2.5 kg, +5kg and +13 respectively. The female subject was also able to perform 15 dips where as previously she had been unable to perform any. On the 100m. time trials both subjects had improvements. The male subject's time went down from 24.68 s to 20.24 s whereas the female subject's times went from 31.83 s to 27.19 s. Table one summaries the results.
The training programme appears to have been beneficial for these two athletes in terms of improving their 100m times, muscular endurance and body composition. The male subject has gained weight (+1.3 kg) and yet his skinfold measurements decreased. This suggests that he has gained fat-free mass and lost fat mass after the nine week period. The female subject also had lower skinfold measurements, but lost rather than gained weight. This suggests that she has lost fat mass. It was expected that, due to gender and age, the male subject would gain more fat-free mass.
The male and female subject improved their peak and mean power outputs following the nine-week training period. This was expected as the Wingate test is an anaerobic test and the training programme was predominately anaerobic. The male subject, although stronger and faster than the female subject, had a lower peak power output (157 W versus 190 W) but a greater mean power output (148 W versus 123 W). One explanation for this is that the male subject's disability means that he does not have a very stable sitting position. The Wingate test required him to stretch to reach the pedals and this stretch put him in an unstable position. As a result he was unable to reach a true peak power score. This is further supported with his rate of fatigue which was only -0.91 W/ s. The female subject, although in a more stable position, also had to stretch in order to reach the pedals. It is unlikely that she would have been able to produce a true estimate of her peak power output in such a position. Therefore the Wingate test may not be a suitable test for these subjects in determining their true peak power output.
In the muscular endurance tests both subjects showed considerable improvement. The male subject had a large increase in his bench press (+12.5 kg) whereas the female had only a small increase in her bench press (+2.5 kg). This was expected due to differences in age and gender. The pull down exercise did not produce a great increase in either subject. Again, for the male it was his stability that proved to be the limiting factor. The male subject had to be strapped to the machine so he could perform the exercise. Although efforts were made to make him as secure as possible, he still had trouble keeping his balance on the seat and also had trouble exerting maximum effort. As he was lifting greater than his body weight, he was being pulled off the seating during the eccentric phase of the exercise. On the dips and triceps exercises both subjects showed considerable improvement. Also of interest was that the female subject was able to perform 15 dips, whereas before the training period she was unable to perform any. The 100m time trials were also improved following the nine- week period. The male subject took 4.44 s off his time and the female subject took 4.64 s off her time.
Before the study the athletes had used a traditional high-volume training programme and had not done any strength training. The results indicate that the new training programme was beneficial in terms of improving their body composition, muscular endurance, anaerobic power and 100m sprint times. The training programme had to be tailored to each subject's functional ability. This is perhaps a key finding of the study. Not only do training programmes have to be specific to the metabolic and physiological requirements of the athlete, they have to be specific to the physical requirements of the individual athlete. In light of the male subject's stability needs, future study is needed to consider alternative ways of assessing muscular endurance and anaerobic power with young individuals with disabilities. Further research is necessary on the effects of strength training in wheelchair racers during a controlled study. This work is currently ongoing at the University of Wolverhampton.
Nick Draper and Jules Woolf
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