Determination of cardio-respiratory fitness is restricted to within the laboratory
because of its exhausting and difficult experimental protocol. It is therefore
desirable to find a simple procedure for evaluation of maximum oxygen consumption
in population studies, especially in the field and in the absence of a well
equipped laboratory. Among various indirect protocols, the Queens College
step Test (QCT) is the simplest one, which is frequently used to determine the
cardio-respiratory fitness in terms of maximum oxygen uptake (DAlanzo
et al., 2006; Bandyopadhyay, 2008).
Recently, we reported that the VO2max seen in tall girls on the
both Queens step test and maximal treadmill test, may be due to their
physiological and physical properties (Bolboli et al.,
Chatterjee et al. (2005) reported that the QCT
has been standardized among Indians, who can easily perform this test without
any premature exhaustion probably for its simple experimental protocol with
lower stool height and slower cadence (Chatterjee et
al., 2005, 2004). Bandyopadhyay
(2008) indicated that QCT can be considered as an alternative step test
of Harvard Step Test (HST) in Indian population provided it is properly validated
and recommended. The application of QCT as an alternative of HST for determination
of Physical Fitness Index (PFI) in Indian males has been already been established
Researchers designed and developed steps adjustable to the height of subjects
in order to optimizing the prediction of maximum oxygen consumption by the means
of the Queens step test (Howley and Turner, 2004;
Welch et al., 2002; Mazic et
al., 2001). During stepping, the biomechanical and work rate is determined
by the step height (Francis and Brasher, 1992). Welch
et al. (2002) studied the reliability of the three minute step test
in order to prediction of maximum oxygen consumption with a specific stepping
frequency. Their results showed that the three minute rate-specific and height-adjusted
step test, predicts maximum oxygen consumption more accurately than fixed height
step tests (Welch et al., 2002). In addition, Culpepper
and Francis (1987) showed that a 73.3 degree angle in the thigh joint is
the most suitable angle for the prediction of maximum oxygen consumption in
the step test. Shephard (1966) claims that estimation
of maximum oxygen consumption regardless of the effect of height is a precise
and reliable test.
On the other hand, Keren et al. (1980) indicated
that physical properties such as weight and height do not affect the prediction
of maximum oxygen consumption in the step test. In other word, maximum oxygen
consumption is independent of weight and height.
Furthermore, Ashley et al. (1997) reported that
step tests based on subjects stature do not more accurately predict the
aerobic capacity than those using a standardized bench height. Willmore
and Costill (1994) demonstrated that due to inverse relationship between
stepping heart rate immediately after physical activity and maximum oxygen consumption,
heart rate is regarded as the criterion to prediction of maximum oxygen consumption.
According to this literature, as the Queens step test with a fixed height is used to predict maximum oxygen consumption in all individuals regardless of height differences, the aim of this study was to explore the impact of active young men height on the estimation of maximum oxygen consumption.
MATERIALS AND METHODS
Participants: Twenty healthy active young men volunteered to participate
as subjects after all procedures were explained; a medical history questionnaire
completed and informed consent signed. The University of Mohaghegh Ardabili
Human Subjects Committee approved all experimental procedures. The medical history
questionnaire screened potential volunteers for any health-related problems
that might affect the parameters measured. All subjects were randomly allocated
into two groups of short and tall. They did not drink alcohol on a regular basis
and had not any programmed physical activity for at least 72 h before experiment
were studied. They did not take any drugs which may be affects the heart rate
throughout the study. Subjects physical characteristics and skin fold
measurement taken from three sites (midaxillary, abdominal and suprailiac) are
presented in Table 1.
Experimental design and procedures: All subjects, prior to enrollment
into the study, completed one preliminary visits to the laboratory before undertaking
the main exercise trails. In this day, subject mass (model 712; seca, Germany)
and height (Portable Stadiometer; Holtain, UK) were recorded; then all subjects
completed a body composition assessment. In addition, the subjects were instructed
to abstain from strenuous exercise for 3 day before main trial.
||Physical and body composition characteristics of subjects
|Data are expressed as Mean±SD
On the day of the main trails, the subjects reported to the laboratory at approximately
the same time of day (±1 h) during 3 subsequent days and completed the Queens
step test and maximal treadmill tests, respectively.
Maximal treadmill test: Following a 10 min warm-up consisting of running at 50% VO2max (5 min) and stretching (5 min), subjects run on treadmill until volitional exhaustion. The maximal treadmill test consisted of increases in treadmill speed every minute until subjects volitional exhaustion. Respiratory exchange was measured continuously throughout the test by an automated open-circuit gas analysis system. The highest averaged 30 sec oxygen uptake VO2max value was defined as maximum oxygen consumption.
Queens step test: As the queens step test is a submaximal
exercise test, all subjects after 5 min warm-up, stepped up and down on the
41.7 cm platform at a rate of 24 steps per minute, for a total of 3 min. Subjects
were instructed to maintain their determined stepping rhythm during Queens
step test. The subject immediately stopped on completion of the test and the
heart rates are counted for 15 sec from 5-20 sec of recovery (Nieman,
1993). HR was continuously monitored using short-range telemetry (Polar
S610; Polar Electro, Finland). Maximum oxygen consumption calculated using the
Maximum oxygen consumption (mL/kg/min) = 111.33-0.42
x heart rate
Body fat percent evaluation: Mechanical harpenden caliper was used to
measurement of skinfold thickness and three point Jackson-Pollack equation for
prediction of body fat. Measurements were taken when the skin is dry and not
overheated (Nieman, 1999).
Statistical analysis: All data are presented as Mean±SD. Statistical
significance was set at the p<0.05 level. Subject physical characteristics
were compared under two groups using independent samples t-tests (Table 1).
Maximal oxygen consumption data obtained by the means of Queens step test
and maximal treadmill test were compared with using paired samples t-tests.
For statistical analysis of data inferential (paired t-test), were used. Graphs
and figures were drawn using Excel software and data analysis was performed
using SPSS 10.05 software under windows.
Findings of this study showed that tall young active men revealed greater maximum
oxygen consumption on the Queens step and maximal treadmill tests
than short ones (Table 2). In fact, mean maximum oxygen consumption of both
groups was greater in the Queens step test than in the maximal treadmill
Comparison of maximum oxygen consumption of both groups in the two treadmill
and the Queens step tests revealed significant differences in the mean
maximum oxygen consumption. Predicted maximum oxygen consumption in both groups
was greater in the Queens step test than in the treadmill test (Table 3).
An association between aerobic capacity and height of active young men also
shown in Fig. 1 and 2. The results also,
revealed a significant correlation between height and predicted maximum oxygen
consumption in the Queens step (R = 0.780; p ≤0.01) and treadmill (R
= 0.739; p≤0.01) tests (Fig. 1, 2).
||Predicted maximum oxygen consumption of tall and short subjects
by the means of Queens and maximal treadmill tests
||Results of the paired samples t-test in the treadmill and
Queens step tests
|*Difference is significant at 0.001 (p<0.001)
||Correlation between subjects height and maximum oxygen consumption
in the treadmill test
||Correlation between subjects height and maximum oxygen consumption
in the Queens step test
Bolboli et al. (2008) reported that taller sedentary
girls had greater VO2max than short ones in the Queens step
and treadmill tests. Accordingly, we studied in this study the impact of height
on the estimation of maximum oxygen consumption among the active young men.
Results of this study revealed that tall young active men showed greater maximum
oxygen consumption on the Queens step test than short ones. Associations
between aerobic capacity and height and weight of young footballers, female
swimmers and 15-25 years old individuals (men and women) have been reported
by Culpepper and Francis (1987), Chen
(1985) and Montoye et al. (1977).
This results indicated that comparing treadmill test; Queens step test
overestimates the maximum oxygen consumption in the both tall and short subjects.
On the other hand, literature indicated that Queens step is a reliable
test for the prediction of maximum oxygen consumption. Bandyopadhyay
(2008), DAlanzo et al. (2006) and Chatterjee
et al. (2005) have shown the Queens step test to be reliable
for the estimation of maximum oxygen consumption. In addition, researchers have
shown that height-adjusted step test is a valid and reliable measure of maximum
oxygen consumption in field conditions (Welch et al.,
2002; Mazic et al., 2001; Gosling
and Carlson, 2000; University of Alabama and Birmangam,
1992; Francis and Fenstein, 1991).
On the other hand, concurrent with the earlier (Bolboli
et al., 2008) and this study results, Ashley et
al. (1997) showed that step tests based on subjects stature do
not more accurately predict the maximum oxygen consumption comparing with standard
steps. A brief review of literature indicates that studies due to different
methodology has been shown different results regarding the influence of height
on the estimation of maximum oxygen consumption by the Queens step test.
As maximum oxygen consumption among the tall subjects comparing with short
ones was similar in the both tests, it appears that long leg length and easy
administration of the test by the tall subjects during Queens step test
may not a only affecting factor for predicting of maximum oxygen consumption.
Hence, tall subjects due to greater lean body mass (Table 1)
and larger lungs size than in their shorter counterparts, may be had higher
maximum oxygen consumption. Thus, according to earlier (Bolboli
et al., 2008) and this study results it seems that height adjustable
steps which designed for optimizing the estimation of maximum oxygen consumption,
may not a unique determinant for validating of predicted VO2max values.
It should be noted that other physiological factors such as lungs capacities
and variables and movement pattern may be involved, which require further investigation.
Generally, based on findings of this study, we concluded that taller subjects had greater maximum oxygen consumption than short ones in the treadmill and Queens step tests. In addition, maximum oxygen consumption overestimated by the Queens step test in the both tall and short subjects.