Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

Abstract

The present study investigated whether 'break-points' in breathing pattern correspond to the first ([Formula: see text]) and second gas-exchange thresholds ([Formula: see text]) during incremental cycling. We used polynomial spline smoothing to detect accelerations and decelerations in pulmonary gas-exchange data, which provided an objective means of 'break-point' detection without assumption of the number and shape of said 'break-points'. Twenty-eight recreational cyclists completed the study, with five individuals excluded from analyses due to low signal-to-noise ratios and/or high risk of 'pseudo-threshold' detection. In the remaining participants (n = 23), two separate and distinct accelerations in respiratory frequency (f (R)) during incremental work were observed, both of which demonstrated trivial biases and reasonably small ±95% limits of agreement (LOA) for the [Formula: see text] (0.2 ± 3.0 ml O(2) kg(-1) min(-1)) and [Formula: see text] (0.0 ± 2.4 ml O(2) kg(-1) min(-1)), respectively. A plateau in tidal volume (V (T)) data near the [Formula: see text] was identified in only 14 individuals, and yielded the most unsatisfactory mean bias ±LOA of all comparisons made (-0.4 ± 5.3 ml O(2) kg(-1) min(-1)). Conversely, 18 individuals displayed V (T)-plateau in close proximity to the [Formula: see text] evidenced by a mean bias ± LOA of 0.1 ± 3.1 ml O(2) kg(-1) min(-1). Our findings suggest that both accelerations in f (R) correspond to the gas-exchange thresholds, and a plateau (or decline) in V (T) at the [Formula: see text] is a common (but not universal) feature of the breathing pattern response to incremental cycling.

Respiratory Frequency during Exercise: The Neglected Physiological Measure

“…When these devices have been used during exercise, f R is typically used for limited applications such as the estimation of the ventilatory threshold during incremental exercise (Hailstone and Kilding, 2011 ). Whilst, the disproportionate and progressive increase in f R , which begins with attainment of the first ventilatory threshold, may be used as a practical non-invasive method for estimating the ventilatory thresholds (Cross et al, 2012 ), there are other important reasons why athletes should consider monitoring f R during training.…”

Ventilatory Thresholds Estimation Based on ECG-derived Respiratory Rate

“…For these reasons, studies based on electrocardiogram (ECG) derived parameters such as ventricular repolarization instability [7] or heart rate (HR) [1,8] were developed by researchers as cheap, simple to perform and non-invasive methods for determining ventilatory thresholds. A computerised method that used polynomial spline smoothing presented in [9] has been employed to determine these abrupt accelerations in respiratory rate which are considered surrogates of VT1 and VT2. The objective of this work is to propose a new method that estimates VT using the respiratory rate derived from single lead ECG.…”

Estimation of Respiratory Frequency in Women and Men by Kubios HRV Software Using the Polar H10 or Movesense Medical ECG Sensor during an Exercise Ramp

“…From a practical standpoint, the EDR seems to yield equivalent RF patterns as the GE noted in Figure 3 . Since previous studies showed potential for RF breakpoints to correspond with ventilatory thresholds [ 2 ], it would be of interest to see if EDR could achieve a similar result. A recent publication showed that both first and second ventilatory threshold identification is possible with EDR methodology [ 25 ].…”

“…However, there are scenarios in which RF estimation can be helpful in exercise science. These include ventilatory threshold measurements, assessments of work rate intensity, and decreases in exercise performance [ 2 , 3 , 4 ]. Though minute ventilation (the tidal volume x RF) has received attention for intensity estimation purposes [ 5 ], the respiratory rate itself has been shown to be quite sensitive in this regard as well [ 1 ].…”