VO₂ Max Testing in Houston, Texas

The anaerobic threshold (AT) is defined as the level of exercise intensity at which lactic acid builds up in the body faster than it can be cleared away. Lactic acid build up generally leads to muscle fatigue and soreness. Vigorous effort can be sustained for an extended duration at exercise intensity levels below the anaerobic threshold. AT can be detected by 2 different means: Ventilatory Threshold, or Respiratory Exchange Ratio threshold.

Respiratory Exchange Ratio (RER) is the ratio of expired carbon dioxide to oxygen uptake at the level of the lung. When Carbon dioxide production exceeds oxygen uptake, the RER crosses 1.00. This is anaerobic threshold.

Ventilatory Threshold (VT) is the point during progressive exercise in which ventilation increases disproportionately to oxygen uptake. Ventilation increases to rid the body of the excess Carbon dioxide from lactic acid build up. AT is detected by pinpointing the take off (rising) point in the Ve/VO2 ratio. (Meyers, 1996)

Lactate Threshold is a reference to the accumulation of Lactate in the blood. There are some inconsistencies in the terminology, though. Some use the term to denote the initial rise in lactic acid production. More often, Lactate Threshold is used to describe the maximum steady state effort that can be maintained without lactate continually increasing. This abrupt increase in blood lactate levels is also referred to as the lactate turn point (LT), lactate inflection point (LIP), or onset of blood lactate accumulation (OBLA). (Roberts & Robergs 1997)

The Anaerobic Threshold is defined as the level of exercise intensity at which lactic acid builds up in the body faster than it can be cleared away. Because this is measured by Ventilatory responses (Ve/VO2 or VO2/VCO2), it is often more accurately termed Ventilatory Threshold (VT). (Meyers, 1996)

Respiratory Exchange Ratio (RER) is the ratio of expired carbon dioxide to oxygen uptake at the level of the lung.

Respiratory Quotient (RQ) is the ratio of expired carbon dioxide to oxygen uptake at the level of tissue or cells. Sometimes this term is used interchangeably with RER, but that is incorrect. A VO2 Max test measures RER. (Meyers, 1996)

The key to determining Anaerobic Threshold (AT) during a VO2 Max test is to detect the point when the body is forced to expel the surplus CO2 produced as a result of excess lactate. This can be determined one of 2 ways:

Measuring VCO2/VO2 (volume CO2/volume O2) and detecting the point when that ratio (RER) equals 1.00. This is the Respiratory Exchange Ratio method.
Measuring Ve/VO2 (Minute Ventilation/volume O2) and detecting the respiratory compensation point. This is the ventilatory equivalent method.
Multiple studies (1,2) have shown that both methods are valid and reliable for determining AT among healthy subjects. KORR offers products that utilize both methods of AT detect to best meet customer needs. A comparison of methodologies in detection of the anaerobic threshold. Dickson K, Barvik S., Aarsland T, Snapinn S, KarlssonJ. Circulation 1990 Jan;81(1 Suppl):II38-46. A new method for detecting anaerobic threshold by gas exchange. William L. Beaver, Karlman Wasserman, and Brian J. Whipp Journal of Applied Physiology 60:2020-2027, 1986

Women typically tend to have a lower VO2 Max than men.

For men and women, VO2 Max will decrease by 10% per decade regardless of age and exercise activity.

VO2 Max is unique to each person and directly proportional to their height, weight, and body surface area. VO2 Max correlates 0.63 with body mass, 0.85 with fat-free body mass, and 0.91 with active muscle tissue.

VO2 Max is reduced for residents of temperate or tropical areas (compared to those living in circumpolar regions). Also, VO2 Max is reduced by approximately 26% at an altitude of 4,000 meters. This reduction increases as altitude increases.