Aerobic threshold
In cross-country and middle-distance sports, the calculation of exercise intensity is fundamental to successful training; it is a matter of accurately identifying and measuring some "quantities" or "parameters" that reflect the effectiveness and efficiency of our energy metabolisms. The most useful are:
- Maximum heart rate (HR max): maximum number of heart beats per minute; is obtained through the performance of maximal stress tests or with the 220-age formula of the subject .
- Aerobic power (PA): it is calculated indirectly by measuring the amount of oxygen consumed in each minute (mlO 2 / min) of MAXIMUM effort (VO2max) through spirometry under stress or by incremental tests; it is a value that indicates the overall capacity of the organism to exploit the aerobic metabolism (even after the activation of the lactic acid metabolism) and it is located near the HRmax. Apparently the aerobic power is genetically determined, but can be improved by around 10-25%.
- Aerobic threshold (SAE) : it is a parameter that indicates the MINIMUM threshold of an intensity range characterized by the NON-LIMITING intervention of the LACTACID anaerobic metabolism; during the exercise performed in the aerobic threshold, lactic acid concentrations of around 2mmol / l are detected in the blood. It is calculated with precision above all (BUT NOT ONLY) by chemical analysis of the blood.
- Anaerobic threshold (SA): it is a parameter that represents the MINIMUM intensity threshold capable of causing lactate accumulation; the anaerobic threshold (which graphically represents ALSO the deflection point [VD] - see Conconi test), can be detected with incremental tests, with the chemical analysis of blood (lactic acid> 3.9mmol / l) and with spirometry under strain.
Both the aerobic threshold and the anaerobic threshold can be improved by stimulating two essential skills:
- Effectiveness and efficiency of aerobic metabolism (training in the ANAerobic threshold)
- Ability to dispose of lactic acid (training at intervals or repeated above and below the anaerobic threshold)
Calculation of the aerobic threshold
The aerobic threshold represents a particularly useful value in the marathon runner's, cyclist's and tri-athlete's race strategy; it is possible to affirm that the aerobic threshold speed corresponds to the ideal speed to face and complete at best a performance lasting about 2 hours (for example, duration of the marathon of 42.195 km), as it represents the minimum intensity of metabolism triggering anaerobic with CONSTANT maintenance of minimum lactate values.
To calculate the aerobic threshold it is possible to intervene with several more or less precise and reliable methods:
- Percentage calculation related to the maximum heart rate THEORETICAL : once the HRmax value (220-age) is obtained, it is possible to obtain the aerobic threshold value by conventionally calculating 60% of the total [not very precise method] .
- Development of an incremental test: the Conconi Test and the Cooper Test are two protocols of fundamental importance for determining the VD or SA in the sportsman and the athlete; in practice, it is possible to identify the aerobic threshold by conventionally calculating the 75-85 of the SA. Furthermore, performing a periodic test (1 or 2 times a year) means obtaining a complete overview of cardiac progression during incremental and maximal exertion (cardio-circulatory, respiratory and muscular fitness indicator), a fundamental or at least very useful detail in the accurate determination of an occult value such as the aerobic threshold [precise method] .
- Gas monitoring in spirometry : this practice is considered almost obsolete due to the cost of the materials; gas monitoring is born as a method of calculating VO2max under maximal stress. In sports practice, the detection and comparison of inspired O2 and expired CO2 are useful in determining the actual use of aerobic mechanisms. Obtaining the VO2max it is possible to identify the aerobic threshold by performing a percentage calculation on aerobic power: aerobic threshold = 70-80% VO2max (Elite athletes), 50-60% VO2max (amateurs, beginners) [precise method] .
- Monitoring of lactic blood acid : through the detection of blood lactic acid under stress it is possible to establish at each STEP of intensity what is the commitment of the lactate metabolism and the catabolite disposal capacity. By obtaining values of 1.8-3.2mmol / l that remain unchanged at constant speed, it is possible to determine not only the MINIMUM point of the aerobic threshold but the entire range preceding the VD or ANAerobic threshold [very precise method] .
The aerobic threshold occurs with a slight increase in blood lactate levels, while the anaerobic threshold occurs with a significant surge in blood lactate levels
The evaluation of the aerobic threshold is fundamental for the estimation of the race speed in the marathon and in all the activities that base the race performance on aerobic endurance (very long duration of exercise).
- In other words, the aerobic threshold can be defined as the minimum training stimulus, ie the minimum intensity at which a subject should exercise if he wants to obtain a minimum training effect that improves performance. Training below this threshold can therefore be considered a waste of time.
