The differences in subjects performance with maximum test in relationship to VO2max, anaerobic threshold and economy. To examine the performance of the subjects in relation to the physiological changes occurring during the maximum tests.
Method
Experimental Design
This study aimed to examine the differences between trained and untrained endurance participants in a controlled Max Vo2 test using a velotron cycle ergometer to perform a maximum incremental exercise test. While also having a Cortex metalyser record the ventilatory response to the workload.
Participants
The subjects were chosen from a exercise physiology year 2 class from EIT in Hawkes Bay
All participants are healthy adults and physically active, of the four subjects Tim and Stef were aerobically trained in endurance cycling while Darcy and Effie are have been involved in anaerobic sports power lifting and sprinting and are relatively untrained aerobically.
Procedure
The subjects demography were recorded age, weight, height and exercise habits
Velotron Cycle Ergometer Test
An indirect Vo2max test in a whole body exercise used involved setting up a velotron cycle ergometer to the correct size for the subject to perform a maximal incremental exercise test. The subject had the option of starting with a four minute warm up using a zero work load but given the test was initiated at a low work load it was not deemed a requirement. A Cortex metalyser 3B was used to measure ventilation gas exchanges with the use of a mouth and nose apparatus creating a seal. The metalyser then was calibrated to the environments O2 / CO2 levels and ventilation flow with a 3L calibration syringe.
The cycling cadence was set at 70 rpm and an initial workload of 50 watts was applied, the test was ramped with workload increasing by 25 watts per minute of the test. The test was terminated voluntarily by the subjects or when the set cadence of 70 rpm could no longer be maintained. The subject’s gas exchange parameters were recorded on to computer at 20-second intervals along with heart rate and power output. VO2max was defined as the highest reading over a 20 second period.
The subject’s heart rate, perceived exertion and O2 saturation were recorded as indication of level intensity.
Storer Davis Cycle Test
Set up the cycle ergometer the same way as in the maximum ramp test. The cadence is set at 60 rpm and a initial workload of 15 watts is set(.25 kp x 60 rpm) then the workload was increased by 15 watts per minute. The test was terminated when the set cadence of 60 rpm could no longer be maintained. The subject’s heart rate, perceived exertion were recorded as indication of level intensity.
Analysis
Velotron Cycle Ergometer Test
The analysis of the data was recorded by the Cortex metalyser 3B(USA) and then graphed using Microsoft Excel.
Storer Davis Cycle Test
The Vo2max results were calculated with
Males
VO2max (ml/min) = (10.51x power(watts) + (6.35*bodyweight(kgs)-(10.49*age(year)
= ml/min / weight = Ml/kg/min
Females
VO2max (ml/min) = (9.39x power (watts) + (7.7*bodyweight (kgs)-(5.88*age (years)
= ml/min / weight = Ml/kg/min
Results
Figure 1
Figure 1 shows the power production compared with their relative Vo2max.
Figure 2
Figure 2 shows the Ventilatory Equivalent for oxygen, which is the ratio of air breathed and the actual amount of oxygen up taken by the body. This is an indication of breathing economy; there is a clear difference between the trained and untrained subjects with Darcy and Effie getting as high as 50 litres of air breathed to one litre of actual oxygen up taken.
Using Ventilatory breakpoints to predict Anaerobic Thresholds
VE/Vco2)
Figure 3
Tim Ventilatory break point occurs around 275 watts, which is 68% of his Vo2max, which is where his VE/Vo2 ratio increases and VE/Vco2 stays relatively constant.
Figure 4
Stef”s Ventilatory breakpoint occurs around 287 watts, which is 85 % of her VO2max, where VE/Vco2 is relatively constant but the VE/Vo2 ratio increases sharply.
Figure 5
In figure 5 a line shows the Ventilatory breakpoint for Darcy at around 258 watts which is 80% of his VO2max, this is where the VE/Vo2 increases sharply compared to the VE/Vco2 ratio.
Figure 6
Effies VE/Vo2 ratio increases sharply compared to her VE/Vco2 at around 175 watts, which is 88% of her VO2max.
Comparison between Cycle Ergometer
VO2 Maximum Test and Storer Davis Results
Predictive Vo2 max test
Table 7
These results in Table 7 some significant differences between the two different test results. There was a increase in power production of 23 % on average in the Cycle ergometer test compared to the Storer Davis test. With the trained subjects Vo2maxs increasing by a average of 13 % and the untrained subjects decreasing by 6 % between the Storer Davis test and Cycle Ergometer VO2 Maximum Test.
Discussion
The differences in subjects performance in a maximum test in relationship to VO2max, anaerobic threshold and economy. To examine the performance of the subjects in relation to the physiological changes occurring during the maximum tests.
As the potential VO2max is reached in a trained individual at a relatively early age 18-22 there are different components that can be addressed to increase performance in the individual. With the anaerobic threshold that can be trained and economy that produce physiological changes in the individual to enable them to work at higher rates of their VO2max(Scott Power & Howley, 2004).
Economy
As power production is an important component of performance figure one show the power produced in relation to actual VO2max, this is a good indicator of how the subjects use their O2 consumption and or what energy systems they relied on in the test. The subjects with a lower VO2 and higher body weight tend to higher ratio e.g. Darcy with 8.69 w/ml/kg/min compared with Stef with 5.38 w/ml/kg/min but both achieving the same end result in the test. Using a ratio like this can help the subjects work on increasing their power output to achieve a higher maximum power output.
Therefore, by Stef increasing her power output she could move her curve to the right perform better in the test but still have the same VO2max.
In figure 2 is shown some clear difference between the trained and untrained subjects as this figure is showing the breathing economy of the individuals and the great difference in the ability of the subjects to utilize the oxygen been ventilated with darcy and Effie ventilating 50 litres to every one litre of oxygen used. This could be a physiological response to untrained subjects using their anaerobic system to get them through the test and the body trying to clear the large amounts of CO2 from the blood. The trained subjects ratios are far more stable point to the fact that their body are more adapt at dealing with lactic acid build up with in the muscle(John A. Hawley, Kathryn H. Myburgh, & Timothy D. Noakes, 2006)
Anaerobic threshold
In Blain, Meste and Bouchard their results show that train individuals have higher anaerobic thresholds then sedentary individuals(G Blain, O Meste, & T Bouchard, 2004 ), used ventilatory breakpoint to estimated the subject anaerobic thresholds pointing to a disproportionate increase in oxygen consumption compare with carbon dioxide production(Scott Power & Howley, 2004). In this labs subject the anaerobic threshold was estimated off figures 3-6 for each individual and then a comparison made with their percentage VO2max. The anaerobic individual Darcy 80% and Effie85% had relatively high anaerobic thresholds in comparison to Tim’s of 68%. This would point to their body compensating for the lower VO2max with a higher threshold so enable them to get further in the test and relates back to Figure 2s high ventilatory output to clear the CO2 levels. Stefs Anaerobic threshold was high to this may relate to her current training cycle and the factor of an injury.
Increasing anaerobic threshold can correspond in the individual been able to at a high level of their VO2max for longer periods of time increasing their overall performance(McMillan, 2006).
Ventilatory breakpoint is an non obtrusive way of estimating anaerobic threshold, and is a basic assessment to detect disproportionate increases in oxygen uptake compare with CO2 expiration which is known to be related to lactate thresholds. Using blood lactate concentration is the most direct and reliable method to detect anaerobic thresholds(G Blain, O Meste, & T Bouchard, 2004 ).
There were some interesting results in the differences between the VO2 ramp test and the Storer Davis test. All the subjects increased their maximum power outputs from the Storer Davis test to the VO2max ramped test, this may correspond to a shorter duration of the test so the participants could use their anaerobic energy systems to get them further.
Practical applications of results
An individual’s performance in sport is not contingent of their VO2max results, there performance can be improved by increase their anaerobic threshold % of VO2max and improve their economy in the activity with conditioning training.
References
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G Blain, O Meste, & T Bouchard. ( 2004 ). Assessment of ventilatory thresholds during graded and maximal exercise test using time varying analysis of respiratory sinus arrhythmia , Universite de Toulon-Var, Nice, France, Nice.
John A. Hawley, P. D., Kathryn H. Myburgh, P. D., F.A.C.S.M., & Timothy D. Noakes, M. C., MD, F.A.C.S.M. (2006). MAXIMAL OXYGEN CONSUMPTION:
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McMillan, R. P. (2006). INTERRELATIONSHIPS BETWEEN MITOCHONDRIAL FUNCTION,
MAXIMAL OXYGEN CONSUMPTION, RUNNING ECONOMY, AND DIET IN
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