The null-hypothesis that "In women's hockey, there is no significant difference in the total energy expenditure (estimated from heart rate) for one player over several matches" was rejected. This shows that despite competing in matches of a similar competitive level players may be subjected to differing workloads. This has implications for the players from the stronger teams as there may be several weeks where they play at a reduced work rate and are then required to play at a greater intensity against a team of similar standard.
The range of energy expenditures found for the least and most demanding matches for each subject in Chapter 4 (difference 2.2- 26.4%), identifies the problems of using an analysis of a single match to observe the physiological demands of "multiple-sprint" sports. Players monitored in a single match may show significant differences in total energy expenditure and time spent in high intensity activity and this may not be a good measure of the metabolic demands placed on the player throughout the season.
The time-motion analysis in Chapter 5 monitored a single match for each subject, consequently the results of this study must be treated with caution as the results might represent the most, least or mean workload for the season for each subject.
8.5.3 Aerobic fitness
The null-hypothesis that "There is no correlation between a player's aerobic power and the time spent in high intensity activity" was
rejected. The correlation of 0.72 found in Chapter 5 between the time
spent in high intensity activity and a player's VO2 max (ml.kg'^.min'^^
suggests that to a certain extent the player's work load during the game is related to her aerobic fitness. The importance of aerobic fitness for performance in "multiple-sprint" sports was emphasised by Tumilty et al. (1993) who found a significant negative correlation between the decrement in sprint performance (for multiple sprints
during simulated match play) and a player's VO2 max. Tumilty et al.
or anaerobic capacity and "multiple sprint" performance, implying that the ability to reproduce speed is of more importance than maximum speed for performance in "multiple-sprint" sports.
8.6 Comparison with other "multiple-sprint" sports
The application of training programmes from one sport to another is only valid if the physiological demands of both sports are similar. Reilly & Borrie (1992) suggested that fitness training programmes developed by soccer players may be applied to the conditioning of hockey players. The results of this study will now be compared both with studies in hockey and studies in other "multiple-sprint" sports. This will determine whether National League women's hockey has similar physiological demands to other levels of hockey and to other "multiple-sprint" sports.
8.6.1 Energy expenditure
In order to compare the rate of energy expenditure directly with values esimated from different sports by other researchers, the rate of energy expenditure has been presented in the form of kj.kg'^^^.min'^ to allow for differences in body weight (Nevil et al. 1992). From this study the mean energy expenditure of women's hockey is in the region of 3.18-3.55 kj.kg'^'^^.min’^ (means of least and most demanding matches for all subjects), the range being 2.49-4.00 kj.kg’^^^.min”^. These values are all greater than the values reported for hockey in the literature, the
exception being the value estimated by Skubic & Hodgkins, (1967) of 2.57 kj.kg'^^^.min"^ for women's hockey and 2.87 kj.kg'^'^^.min"^ (Malhotra et al., 1983) for men's hockey on Astroturf, both of which fall into the bottom of the range found by this study and below the mean of the least intense games for all subjects. This suggests that hockey is now played at a greater intensity than previously documented.
In comparison with other "multiple sprint" sports , McArdle et al. (1971) found a mean energy expenditure of 2.44 kj.kg"^"^^.min"^ for women’s collegiate basketball, with a maximum mean energy
expenditure of 3.16 kj.kg"^^^.min"\ Skubic & Hodgkins (1967) found a
slightly lower energy expenditure of 2.13 kj.kg'^'^^.min'^, both these values were estimated from heart rate. This would suggest that despite
women’s basketball having fewer players which might suggest greater involvement in the game, the work rate was actually lower than that found for women’s hockey.
In soccer, Ali & Farrally (1990) found a mean energy expenditure of 2.64 kj.kg“^'"^.min'^ for semi-professional soccer players estimated from heart rate, which is lower than that reported Reilly & Thomas (1979) of 4.17 kj.kg‘^^^.min“^ for professional soccer players. The mean rates of estimated energy expenditure observed in this study for women’s hockey (3.18-3.55 kj.kg'^^^.min’^^ . suggest that the range of energy expenditure for women's hockey falls within the values
estimated for soccer.
The differences between the values obtained by Ali & Farrally (1990)
and Reilly & Thomas (1979) show the range of energy expenditure that
might be expected within competition at different levels within the same sport. Although the differences observed by Ali & Farrally (1990) between semi-professional and recreational players of 2.64 and 2.39 kj.kg’^^'^.min'^ respectively are not as great as those between the studies of Reilly & Thomas (1979) and Ali & Farrally (1990) for professional and semi- professional players. This suggests that the energy costs of professional soccer is much greater than other levels of competition.
The method used by Ali & Farrally (1990) involved the use of the Leger
20 m shuttle test (Leger & Lambert, 1982) to establish the heart rate
oxygen uptake regression equation. It is doubtful whether this is a:^ valid as measuring actual oxygen uptake at steady state workloads on the treadmill, as the time delay in the heart rate response to increasing workloads may have led to errors in the slope of the regression
equation. Also, a player's running efficiency will govern his oxygen uptake at a specific running speed. Hence the values obtained by
Reilly & Thomas (1979) are likely to be the better estimation of energy
expenditure during soccer match play. Consequently, it can be concluded that, the majority of women's hockey is played at a lower rate of energy expenditure than professional soccer.