Minute ventilation and heart rate relationship for estimation of the ventilatory compensation point at high altitude: a pilot study.

Abstract

BackgroundThe ventilatory compensation point (VCP) is an exercise threshold which has been used in the design of training programs in sports medicine and rehabilitation. We recently demonstrated that changes in the slope of the minute ventilation to heart rate relationship () can be utilized for estimation of the VCP during incremental exercise at sea level (SL). We hypothesized that in hypoxic conditions, such as high altitude (HA), VCP can be also reliably estimated by .MethodsAt SL and on immediate ascent to HA (5,050 m), six healthy subjects (42 ± 14 SD years) performed a maximal incremental exercise test on a cycle ergometer; O2 uptake (), CO2 output (), , and HR were measured breath-by-breath. The method for VCP estimation was compared to the standard method using the ventilatory equivalent for CO2 () and end-tidal PCO2 (PETCO2). The slope values below (S1) and above (S2) VCP were computed by linear regression analysis.ResultsA significant difference between S1 and S2 was observed, at SL and HA, for both the and methods for VCP estimation. A good agreement between the two methods ( vs. ) was found for both environmental conditions; the mean difference ± 2 SD of at VCP (VCP-) was −22 ± 112 ml/min at SL and 39 ± 81 ml/min at HA. The VCP- was significantly lower at HA compared to SL; in addition, S1 and S2 mean values were significantly higher at HA compared to SL.ConclusionAt HA, VCP may be reliably estimated by the method.