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Within the exercise world the most widely accepted measure of cardiovascular fitness is VO2 max. Also known as maximal oxygen uptake, VO2 max is defined by Albernethy et al (1996) as the maximum amount of oxygen than can be absorbed and transported to working tissues for use within the body. This literature also states that athletes with a high VO2 max are typically know to be endurance athletes whereas athletes with a lower VO2 max are classified as either power or sprint athletes. Whilst relationship between types of exercise and VO2 max are clearly defined, the relationship between VO2 max and gender is still a topic which is widely debated within the exercise world.
After reviewing literature from Martin et al (1991), Rowland et al (2000) and Suth (2005) it is evident that males have a higher VO2 max than that of females, regardless of age. Despite this, all articles indicate that body composition and cardiac size are both major determinants of VO2 max. Rowland et al (2000) found that in adolescents, VO2 max is higher in males in both absolute terms and relative to body mass. Interestingly, at the age of 18 males have a 75% greater VO2 max when expressed as an absolute value as opposed to a 25-30% higher VO2 max relative to body mass (Rowland et al, 2000). As we venture into adulthood, females are said to have a body fat content which is 1.7 times greater than males and as a result there is a noteworthy gender difference in VO2 max when looking at absolute values (Suth, 2005). However, when looking at VO2 max relative to lean body mass the differences between genders are reduced by almost 50%. In the study conducted by Martin et al (1991) groups of sedentary and trained men and women were tested for VO2 max. The result yielded from the experiment indicate that males had a greater VO2 max both relative to body mass and when compared to the study groups.
The aim of the current study was to conduct a two submaximal cardiovascular fitness tests on a sample of mixed gender university students in order to examine the relationship between VO2 max and gender. Two submaximal fitness tests, namely the Astrand-Ryhming step test and YMCA Protocol test were used in order to obtain the results and perform the analysis between genders.
The study consisted of a total 83 participants, who were recruited from the faculty of human movement studies during laboratory sessions, which included 42 males and 41 females. Each of the participants was required to complete two fitness tests which aimed at determining their maximal oxygen uptake or VO2 max. Prior to undertaking the fitness tests each participant recorded their gender, age, height and weight by means of classification and analysis upon the tests completion. This data, represented as mean ± standard deviation (SD), is as follows. Males (42) mean ± SD: Age - 19.07 ± 3.85 yrs, Height - 181.39 ± 6.36 cm, Weight - 76.88 ± 8.87 kg. Females (41) mean ± SD: Age - 18.28 ± 1.73 yrs, Height - 181.39 ± 6.36 cm, Weight - 60.05 ± 6.93 kg. In addition the participants were grouped into groups of 2-3, along with recording their 85% HR max for testing purposes.
Prior to the conduction of the Astrand-Ryhming step test and YMCA Protocol test, various conditions of testing were followed in order to ensure the same standard and validity of testing between groups. It was expressed that participants were to have not participated in heavy exercise nor have had and stimulants or heavy means in the four hours prior to testing. Also it was mentioned that participants were to be well hydrated and wearing clothing and footwear appropriate for physical activity. Finally, it must be noted that in ideal circumstances, temperature and humidity levels should be standardised.
Astrand-Ryhming step test:
For this test participants were required to set up steps at specific heights of both 40cm (males) and 33cm (females). In order to complete the test correctly the subjects had to step up and down on the platform at a rate of 22.5 complete ascents and descents per minute. This translated to a 4count on a metronome set at 90 beats per minute (bpm). Each participant was required to step for 6 minutes with their heart rate (HR) being recorded at the end of each minute. It was expressed that the test was not to exceed 10 minutes and the test be stopped if the HR exceed 85% HR max. The test was deemed completed when the difference between the final two values was less than 6 bpm. Upon completion of the test the Astrand-Ryhming nomogram was used to estimate the participants VO2 max.
YMCA Protocol test:
For this particular test, participants were required to cycle for multiple intervals of three minutes according to a modified guide which was based on the participants HR. In order to ensure that the bike was at a comfortable height, students had to adjust the height of the cycle ergometer so that the knee was slightly flexed at the bottom of the downstroke. At the beginning of the test the student was required to pedal at 50 revolutions per minute (rpm) by means of warm up. The first workload on the ergometer was set at 25 watts (W) which the participant cycled for three minutes with their HR being recorded for the last 15 seconds of the 2nd and 3rd minutes. After the first three minutes had been completed the HR from the 2nd and 3rd minutes was analysed to determine the work-rate (WR) category for the remainder of the test, ensuring that the HR for this period differed by no more than 6. The participant then had to continue riding moving to subsequent WR after every three minutes until the successive HR differed by no more than 6 bpm. The test was concluded when the participant had at least two WR with corresponding steady state heart rates between 110 bpm and 85% HR max.
Data Collection Procedures
The data collection process for the Astrand-Ryhming step test required participants to record their HR at 1 minute intervals until the steady state had been reached and the test completed. This raw data was used in correlation with both the participant's weight and Astrand-Ryhming Nomogram to find their Raw VO2 max (L.min). For the YMCA Protocol test a chart was used whereby HR was plotted against WR. Firstly a horizontal line was drawn where the subject's age-predicted HR max lies. Secondly the HR from the last minute of each of the last two WR was plotted against the corresponding WR. Next a straight line is drawn joining these two values as well as intersecting the line of the subject's age-predicted HR max. From this point a vertical line was drawn downwards which intersected the work-rate and VO2 scales below the horizontal axis consequently determining the subjects VO2 levels (L.min).
Data Analysis Procedures
For the Astrand-Ryhming step test, the subject's age determined VO2 max was predicted by using the age correlation factor table which was located in the 'age correction factor for determination of predicted VO2 max' table and multiplying it by the Raw VO2 max levels. Further analysis was conducted by converting this value from L.min to ml.kg.min in order express VO2 max relative to body mass. Like the analysis procedure for the Astrand-Ryhming step test, the relative body mass VO2 max was also determined for the YMCA Protocol test. This method differed from the Astrand-Ryhming step test as the age correction table was not used; instead age was incorporated into the graph for plotting HR against WR.
After completion of the two sub-maximal fitness tests it was evident from the tests that males (49.09 ± 11.48) as a whole group recorded a higher VO2 max level in the YMCA Protocol Test as opposed to females (46.42 ± 11.81). Despite this, when analysing results for the Astrand-Ryhming step test it was discovered that as an entire cohort, females (48.26 ± 10.51) recorded an average higher VO2 max than their male (47.66 ± 8.04) counterparts. In addition, it is evident that males (H: 181.39 ± 6.36 cm, W: 76.88 ± 8.87 kg) have a higher average height and weight as opposed to women (H: 164.34 ± 26.94 cm, W: 60.05 ± 6.93 kg). Figure 1 refers to the average group VO2 max between males and females for both sub-maximal fitness tests. Based on this figure it is evident that males have a higher mean value for both tests than women. Conversely, women have a greater spread of data for the Astrand-Ryhming step test as opposed to men, as well as having higher maximum values for the YMCA Protocol Test. Males seem to have a fairly even spread of data for both tests, which correlates to their higher average VO2 max in the YMCA Protocol Test.
Table 1: Average (± SD) values for males and females age, height (cm), weight (kg) and VO2 max (ml.kg.min)
YMCA Protocol Test (ml.kg.min)
Astrand-Ryhming step test (ml.kg.min)
19.07 ± 3.85
76.88 ± 8.87
181.39 ± 6.36
49.09 ± 11.48
47.66 ± 8.04
18.28 ± 1.73
60.05 ± 6.93
164.34 ± 26.94
46.42 ± 11.81
48.26 ± 10.51
Figure 1: Box plot of average VO2 max between males and females for both sub-maximal fitness tests
The gender differences of VO2 max for the study somewhat reflects the observations and results recorded in previous literature. Previous studies on gender research have indicated that males have a higher VO2 max than that of females, in both absolute terms and relative to body mass (Rowland et al, 2000). It was found that after the completion of the current study that this research was only partly confirmed as males were found to have a higher VO2 max in the YMCA Protocol Test, whilst females recorded a higher VO2 max in the Astrand-Ryhming step test.
It is believed that differences in body composition are the main contributing factor as to why VO2 max levels differ between genders. When analysing height and weight components between males (H: 181.39 ± 6.36 cm, W: 76.88 ± 8.87 kg) and females (H: 164.34 ± 26.94 cm, W: 60.05 ± 6.93 kg), it was evident that males were on average significantly larger than females. This correlates with research conducted by Rowland et al (2000) which states that majority of males can produce a higher VO2 max due to the fact they are anatomically bigger. As a result of their larger size it is known that males have larger chest cavities and consequently larger lungs, which equates to them having a larger lung capacity and consequent VO2 max levels. This evidence is closely associated with the results produced from the YMCA Protocol Test as males (49.09 ± 11.48) produced a considerably higher VO2 max than that of females (46.42 ± 11.81).
Evidently body composition is not the only determinant of VO2 max as personal fitness levels and training background may also play a major part in VO2 max levels (Suth, 2005). In addition to this, personal motivation could have also contributed to the overall results from the tests. Suth (2005) revealed that there is a high correlation between personal fitness, training background and VO2 max regardless of gender. Consequently, regardless of body composition or gender, a person who participates regularly in moderate to vigorous physical activity will have a higher VO2 max than that of a sedentary individual. With the selected sample being human movement studies students, who all have an interest in sport, it is likely that majority of participants would engage in physical activity resulting in them having above average fitness levels. Whilst training background and prior fitness levels were not extensively measured prior to the test is may be assumed that this concept is a possible explanation for the females (48.26 ± 10.51) recording a marginally higher VO2 max than males (47.66 ± 8.04) in the Astrand-Ryhming step test.
Key limitations to this study could have had a direct correlation to the results which were recorded from the study. Mainly the fact that the two sub-maximal fitness tests were performed directly after each other could have had a direct bearing on the results. This is because following the first test, depending on how exhausting it was, the subject could have been pre-fatigued and possibly performing below their optimal performance levels consequently producing a lower VO2 max level. Another limitation to the study is the fact that training background and fitness levels were not extensively analysed prior to the studies conduction. This is particularly evident as all of the studies participants, as they are a part of the faculty of human movement studies, would be assumed to have above average VO2 max levels consequently not providing much difference between males and females. Conversely, if participants of this study were compared against a group of sedentary individual's different results outlining differences between fitness levels and genders could be expected. Similarly, it would be expected that the VO2 max results for the second test would be lower than the first due to fatigue.
Looking forward to the future, ensuring that all participants perform each test in the same order, or possibly on different days, will mean that the results obtained from the tests will project the optimal efforts of the participants. Conversely, a downfall to this would be that it would take more time to obtain results from the two tests. Also, another idea is to groups participants according to body mass and/or height in order to determine whether maximal oxygen uptake is governed by gender or body composition.