22 Type ‘A’ behaviour in squash
3.2 Physiological profiles
Comparative results displayed in Table 2 demonstrate a similarity in body mass for the three groups. The recreational and club groups were found to possess above average total skinfold thicknesses. Significant differences were noted between the recreational players and the elite group (P<0.05).
164 Robertson, Hughes, Sanderson and Reilly
The most significant difference between the groups was their aerobic capacity as measured by VO2 (ml.min-1.kg-1) at 170 beats.min-1. This aerobic capacity index
progressively increased as the group standard increased. Thus, the Elite group scored significantly higher than both the Club (P < 0.01) and Recreational players (P < 0.001).
Table 2. Physiological characteristics of male squash-players Table 1. Comparative results for the Jenkins Activity Survey
Type ´A´ behaviour in squash 165 In accordance with their more favourable aerobic capacity values, the Elite group also possessed significantly less plasma cholesterol than the other groups (both P < 0.05). However, no differences were observed in the amount of high density lipoprotein (HDL) contained within this sample nor on the total
cholesterol: HDL ratio. The results for the Recreational and Club groups exceed the threshold (4.0 mmol.l-1) for very low risk of CHD, but only marginally
(Williams et al., 1979). Overall, the squash-playing sample demonstrated a very positive physiological health profile.
In order to determine the relationship between the physiological measures and Type A behaviour, a correlation matrix was calculated (Table 3). Although the correlation values are moderate, some significant relationships were identified. The VO
2–170 measure was found to correlate with a tendency to display Type A
(r=0.447, P<0.05) and hard-driving and competitive behaviour (r=0.403, P<0.05). It seems that the fitter squash players are more likely to display overt competitive and Type A behaviours. These are primarily subjects within the upper competence group.
The more positive HDL levels were displayed by subjects with Type A tendencies (r=0.436, P<0.05). Similar relationships existed between HDL scores and the Hard-driving subscale (r=0.429, P<0.05).
The Type A behaviour pattern has been linked retrospectively and prospectively with CHD (Review Panel, 1981). Yet in the present study, subjects with higher Type A scores possessed more favourable HDL profiles which paradoxically protects against the occurrence of CHD (Castelli et al., 1977). This is in conflict with previous findings (Glass, 1977) and may be explained by the following: (a) the physiological mechanism for the link between the Type A behaviour pattern
and CHD may not be serum cholesterol. Heart disease refers to a collection of disease endpoints that may vary greatly i.e. angina pectoris, coronary
insufficiency, myocardial infarction. It is possible that psychological factors could have a greater impact on one disease condition than on another (Booth- Kewley and Friedman, 1987). Numerous studies have demonstrated that Type A individuals display larger episodic increases in catecholamines when confronted with challenging or stressful tasks than their Type B counterparts (e.g. Shahidi et al., 1991). Thus, arousal of the sympathetic nervous system may play a more important role in the formation of CHD than serum cholesterol profiles. (b) the threat that Type A behaviour poses to cardiac health may be attenuated by
cardiorespiratory fitness. It has been noted that increased levels of physical fitness are associated with more favourable blood lipid profiles (Seals et al.,
166 Robertson, Hughes, Sanderson and Reilly
1984). Participation in regular exercise has been shown to improve the coronary risk profile of subjects as well as reducing Type A tendencies. Although the competitive nature of squash may negate the expected reduction in Type A scores associated with exercise involvement, the improvements in physiological status seem to have a counterbalancing effect.
(c) the specific behavioural aspects of the Type A pattern may be advantageous in sport contexts and may be exhibited in this context without having negative implications for health. Although the athletes in the present sample were found to possess the behaviour characteristics of the Type A pattern, elite athletes in general display physiological contra-indicators to CHD. It is questionable whether the terms Type A and coronary-prone should be used interchangeably (Matthews et al., 1982)
4 Conclusions
This study has revealed no evidence to suggest that Type A individuals are naturally attracted to squash. The results did, however, indicate a prevalence of Type A behaviour amongst the higher competency groups, suggesting a self- selection mechanism. Higher Type A scores for these subjects were not associated with greater cardiac risk as measured by blood lipid profiles. The relationship between Type A behaviour and heart disease in athletes is an important area for future research.
5 Acknowledgements
This study was funded by the Health Promotion Research Trust 6 References
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