Cardiorespiratory Testing: Anaerobic Threshold/Respiratory Threshold

Abstract

Complete exercise testing is more than simply running on a treadmill or riding on a cycle ergometer. These simple measures may be used to evaluate endurance, peak heart rate, blood pressure, and the presence or absence of dysrhythmias during exercise. With the use of rapid gas analyzers and microcomputers, information about ventilation, oxygen supply and use, and the metabolism at the muscle level may be obtained noninvasively. The concept of the ventilatory anaerobic threshold and the transition from aerobic to anaerobic metabolism during a graded exercise test are discussed. Tests that evaluate only anaerobic performance (i.e., the Wingate test) will not be discussed. Gas Exchange During ExerciseThe amount of oxygen required to perform a given amount of work exclusively aerobically is known and appears to be independent of the degree of fitness, age, or gender of the subject [8,22]. Thus, the failure of the circulation to deliver oxygen at the required rate to sustain exercise will slow the rate of aerobic regeneration of ATP by the muscle. The oxygen supply to the exercising muscles depends on the blood flow, hemoglobin concentration, the partial pressure of oxygen in the patient's arterial blood, and the iron content of the patient's blood. Failure of the circulation to deliver oxygen at the rate needed to sustain exercise will limit the rate of aerobic regeneration of ATP and the oxygen consumption by the muscles (VO 2 ).At very low exercise intensities, the concentration of the blood lactate is nearly identical to levels recorded at rest. At some particular level of exercise intensity, which varies among subjects, blood lactate concentration begins to increase. As the oxygen demand of the exercising muscle exceeds the oxygen supply, anaerobic metabolism is used to supply the energy required to continue work. Lactic acid is a by-product of this anaerobic metabolism. Once formed, lactic acid will be almost completely dissociated in the serum, and it is buffered predominantly by the bicarbonate system.

Evaluation of Right Ventricular Functions and B-Type Natriuretic Peptide Levels by Cardiopulmonary Exercise Test in Patients with Pulmonary Regurgitation After Repair of Tetralogy of Fallot

“…Gas exchange values obtained during exercise, like VO 2 max, VCO 2 max, VAT, or respiratory quotient (RQ), can give more clear information about cardiopulmonary functions. It is accepted as more appropriate to use VO 2 max values because of low heart rate response during exercise in these patients 47 . In our study, five patients and three controls were not able to reach to VAT, and VO 2 max values of them were used during assessment.…”

“…It is accepted as more appropriate to use VO 2 max values because of low heart rate response during exercise in these patients. 47 In our study, five patients and three controls were not able to reach to VAT, and VO 2 max values of them were used during assessment.…”

Respiratory compensation point during incremental test in overweight and normoweight boys: is it useful in assessing aerobic performance? A longitudinal study

“…After exceeding the first ventilatory threshold, the compensated metabolic acidosis is developing, while exceeding the second ventilatory threshold results in decompensated metabolic acidosis and hence, the name of that thresholdthe threshold of the decompensated metabolic acidosis (TDMA). overweight), as it does not require performing maximum effort, and it does cause motivational problems while performing the test evoking the feeling of a heavy exhaustion ('up to refusal') (Di Prampero, 1986;Washington, 1999). Also, the exercise intensity at which the V E /VCO 2 reaches minimum was significantly correlated with that at which the capillary pH decreased significantly.…”

“…The onset of hyperventilation might represent the organism's attempt to compensate for metabolic acidosis (Beaver et al, 1986). This difficulty results from using different definitions of the metabolic thresholds and various methods of their determination (Washington, 1999). As a result, aerobic performance could be determined at three points: at first ventilatory threshold, at second ventilatory threshold (RCP) and at VO 2 max.…”

“…It seems that determining ventilatory thresholds is an easy and a better (than the estimation of VO 2 max) way of assessing aerobic performance, particularly in children with lowered physical capacity (e.g. overweight), as it does not require performing maximum effort, and it does cause motivational problems while performing the test evoking the feeling of a heavy exhaustion ('up to refusal') (Di Prampero, 1986;Washington, 1999). In our study, we chose the RCP to evaluate aerobic performance.…”