Paolo Onorati

The 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 ( Δ V ˙ E / Δ HR ) 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 Δ V ˙ E / Δ HR .

Incremental cardiopulmonary exercise test with gas exchange measurement is the gold standard for the identification of the ventilatory compensation point (VCP). It has previously been demonstrated that the change in the slope of increment of minute ventilation over HR (ΔV˙E/ΔHR) can be used alternatively to the ventilatory equivalent for CO₂ (V˙E/V˙CO₂) method for detection of VCP in healthy subjects undergoing cycle ergometer (C) incremental exercise. The same evaluation during treadmill (T) incremental exercise and comparison between C and T have not yet been performed. We analyzed, during both C and T incremental exercises, the V˙E/HR and the respiratory rate (RR)/HR relationships, expressed either as slope or as an absolute value. We hypothesized that changes in the slope of increment of the two relationships could represent a reliable method for VCP detection, regardless of exercise mode and protocol. Fourteen healthy male subjects (age = 31 ± 7 yr (mean ± SD)) underwent two T incremental exercises--fast (FT) and slow (ST) protocols (8 km·h⁻¹, 2% (F(T)) and 1% (S(T)) grade per minute)--and one C incremental exercise (30 W·min⁻¹). O₂ uptake (V˙O₂), V˙CO₂, V˙E, HR, and RR were measured breath by breath. A good between-method agreement in the detection of VCP by the ΔV˙(E)/ΔV˙CO₂, ΔV˙(E)/ΔHR, and the ΔRR/ΔHR slope changes was found in both T protocols and C. No differences (C vs T and F(T) vs S(T)) were found in the slope of the ΔV˙(E)/ΔHR and ΔRR/ΔHR relationships after the VCP and in the V˙(E)/HR and RR/HR absolute values at VCP. In healthy young males, the ΔV˙E/ΔHR and ΔRR/ΔHR relationships during T and C incremental exercises can be reliably used to detect the VCP as an alternative to the ventilatory equivalent method.

Cardiopulmonary exercise test is the gold standard for the identification of the ventilatory compensation point (VCP), an important threshold for exercise training prescription. We hypothesized that changes in the slope of increment in minute ventilation (V’_E) over heart rate (HR) during incremental exercise can be utilized, as alternative to the ventilatory equivalents method, for VCP detection. In 14 healthy subjects (ten males, four females, age 31 ± 10 SD) we studied the ventilatory, cardiovascular and gas exchange adaptations during two incremental cycle ergometer exercise: (F) fast work rate increments (30–20 watt/min, M-F), (S) slow work rate increments (15–10 watt/min, M-F). A good between-method agreement in VCP detection in terms of oxygen uptake (V’O₂) was found in both F and S protocols (F: −7 ± 118 V’O₂ ml/min; S: −36 ± 144 V’O₂ ml/min). VCP occurred at the same percentage of peak V’O₂ in both protocols. The changes in the V’_E versus HR slope during incremental exercise can be used to detect the VCP as alternative to the ventilatory equivalents method.