In an intensified sprint that utilizes an anaerobic system, more power is required in a short time. Here, there is less efficiency in anaerobic pathways but energy is quickly available. In longer runs that utilize the aerobic system, there is a requirement of steady power output over a long time period. In a moderate run, both systems are in use with low anaerobic, aerobic ratio here, generated lactate is flashed out easily with no build-up. With an increased pace, a point reaches where the anaerobic system produces more lactate than it flashed out. An anaerobic threshold is the beginning of lactate accumulation in the bloodstream.
Wasserman and McIlroy (1964), explain that for a long time exercise physiologists have known about a critical workload that triggers lactate accumulation. They add that the phenomenon of anaerobic threshold is controversial and objectively used in athletes and patients to measure aerobic work capacity.
Measurement of Anaerobic threshold from plots of respiratory variables is possible because the respiratory rate is a reliable indicator. When assessing changes in the anaerobic threshold, oxygen ventilator equivalent is used. Observing a graph of carbon dioxide production versus oxygen consumption, the anaerobic threshold is the point where there is a distinct change in slope.
According to Bhambhani and Singh (1985), a graph of expired minute volume versus oxygen consumption, anaerobic threshold is the first breakpoint at which expired minute volume and oxygen consumption achieves a minimum value, with increasing work leading to hyperventilation with regard to oxygen consumption.
- VE (STPD; L Min-1) = VE (ATPS) x STPD Correction Factor (CF)
- VE (STPD; L Min-1) = 12.3 x 0.892
- VE (STPD; L Min-1) = 10.97
- VO2 (L·min-1) = VE (STPD; L Min-1) x (FIO2 – FEO2)
- VO2 (L·min-1) = VE (STPD; L Min-1) x (0.209- 0.0003)
- VO2 (L·min-1) = VE (STPD; L Min-1) x (0.2087)
- VO2 (L·min-1) = 10.9716 x 0.2087
- VO2 (L·min-1) = 2.29
- VO2 (L·min-1) = VE (STPD; L Min-1) x FECO2
- VO2 (L·min-1) = VE (STPD; L Min-1) x 0.003
- VO2 (L·min-1) = 10.9716 x 0.003
- VO2 (L·min-1) = 0.033
Wasserman, et al. (1973) claim that efforts have been made by physiologists to investigate the relationship between the exchange of respiratory gases and blood lactate levels to ascertain which index best shows the lactate anaerobic threshold. Plots of respiratory variables can measure the anaerobic threshold, using the relationship between expired carbon dioxide and inspired oxygen. Plots of respiratory variable tests are preferable because direct measurement of gases gives greater objectivity.
VO2max is the highest achievable oxygen consumption in this criterion. This is the point at which oxygen consumption stagnates. The other useful criteria for confirmation of VO2max appearance is the plateau in VO2 < 50 mL/min and RER > 1.15 at VO2max (The American Society of Exercise Physiologists,2000).
According to graph 3 below, the oxygen consumption stagnated at 170. This is the point at which the subject reached maximum aerobic capacity. This is indicative of the subject’s cardiorespiratory fitness, aerobic potential and power. The test went on until the subject reached volitional exhaustion. At this point, the subject had difficulty in maintaining 60 rpm with any workload because of fatigue. At this point, the test ended. The test has produced an optimum level at which the exercise was performed. The optimum level or intensity is expressed relative to the occurrence of VO2max. The more the power output, the sooner the subject reaches VO2max. Oxygen uptake does not increase indefinitely with a higher work rate.
There are significant differences between the predicted and measured maximal values. The predicted value using the predicted:
VO2max equation2 overestimated the aerobic capacity hence, was greater than the measured value. The equation takes into account some factors excluded in the measured maximal value calculations. According to Fitchett (1985), the difference between the measured and predicted is that the values are statistically significant for the measured tests. Individual predictions are vulnerable to error.
- VE (STPD; L Min-1) = VE (ATPS) x STPD Correction Factor (CF)
- VE (STPD; L Min-1) = VE (ATPS) x 0.981
- VE (STPD; L Min-1) = 36.3 x 0.981
- VE (STPD; L Min-1) = 35.61
- VO2 (L·min-1) = VE (STPD; L Min-1) x (FIO2 – FEO2)
- VO2 (L·min-1) = VE (STPD; L Min-1) x (0.209- 0.0003)
- VO2 (L·min-1) = VE (STPD; L Min-1) x (0.2087)
- VO2 (L·min-1) = 35.61 x 0.2087
- VO2 (L·min-1) = 7.43
Bodyweight: 78 kg
VO2 in ml/min: 7430 ml/min
7430 ml/78 kg/min = 95.26 ml/78 kg/min
- RER =VO2/VO2
- RER = 0.097/6.75
- RER= 0.0144
References
Bhambhani, Y and M Singh. 1985. Ventilatory thresholds during a graded exercise test. Respiration., pp.120-128.
Davis, JA, VJ Caiozzo, N Lamarra N et al. 1983. Does the gas exchange anaerobic threshold occur at a fixed blood lactate concentration of 2 or 4 mM? International Journal of Sports Medicine., pp.89-93.
Fitchett, M A. 1985. Predictability of VO2 max from submaximal cycle ergometer and bench stepping tests. British Journal of Sports Medicine., p. 85–88.
Wasserman, K and M.B Mcilroy. 1964. Detecting the threshold of anaerobic metabolism in cardiac patients during exercise. The American Journal of Physiology., pp.14, 844-852.
Wasserman, K, B.J Whipp, S.N Koyal, and W.L Beaver. 1973. Anaerobic Threshold and Respiratory Gas exchange during Exercise. Journal of Applied Physiology., pp.35, 236-243.
The American Society of Exercise Physiologists (ASEP). 2000. Incidence Of The Oxygen Plateau at VO2max During Exercise Testing To Volitional Fatigue. Journal of Exercise Physiology. 3(4), pp.6-7.