User's Manual

144 - K4 b
2
User Manual
Calculations references
VO
2
and VCO
2
"Energy Expenditure and Fuel Selection in Biological Systems: The Theory and
Practice of Calculations Based on Indirect Calorimetry and Tracer Methods": M. Elia,
G. Livesey, World Rev. Nutr. Diet. Basel, Karger, 1992, vol 70, pp 68-131.
"Nutritional Assessment in Critical Care, A Training Handbook": Donald C. Zavala
Anaerobic threshold (modified V-Slope)
The break-point or intercept of the two slopes can be selected by a computer program
that defines the VO2 above which VCO2 increases faster than VO2, without
hyperventilation.
During an incremental exercise above the Lactate Threshold, the net increase in lactic
acid production results in an acceleration of the rate of increase in VCO2 relative to
VO2. When these variables are plotted against each other (squared graph without
recovery points), the relationship is composed of two apparently linear components, the
lower of which has a slope of slightly less than 1.0, whereas the upper component has a
slope steeper than 1.0. The intercept of these two slopes is the LT or AT point measured
by gas exchange.
The increase in VCO2 in excess of that derived from aerobic metabolism must be
generated from the buffering of lactic acid. This is an obligatory gas exchange
phenomenon seen in all subjects who exercise to work levels above their LT. This
technique is referred to as the V-Slope method.
OVS, Original V-Slope method: "A new method for detecting anaerobic threshold by
gas exchange", Beaver, Wasswrman, Whipp, JAP 1986, 60:2020-2027.
MVS, Modified V-Slope method: "Metabolic acidosis during exercise in patients with
chronic obstructive pulmonary disease", Sue, Wasserman, CHEST 1988, 94:931-938.
O
2
kinetics
“Delayed Kinetics of VO2 in the Transition from prior Exercise. Evidence for O2
Transport Limitation of VO2 Kinetics: A Review”; R.L. Hughson and M.A. Morrissey,
Int. J. Sports Med. 4 (1983) 31-39
ISO 8996: Ergonomics – Determination of metabolic heat production, 1990
In the following picture it is shown how the O
2
debit and deficit values are computed.