We performed an incremental exercise test on six healthy males with a Starling resistor in the expiratory line limiting expiratory flow to ∼ 1 l s−1 to determine maximal EFL exercise workload (Wmax).
In healthy subjects, limiting expiratory flow by a Starling resistor or increasing expiratory load by imposing a constant pressure at the mouth during expiration, have been shown to significantly reduce cardiac output during exercise (Aliverti et al. 2005a; Stark-Leyva et al. 2004).
Pharmacologically stimulating ventilation increases end-tidal PO2 and SaO2 during submaximal exercise, but not during maximal exercise where many athletes reach a mechanical limit for expiratory flow.
36 Owing to the strong ventilatory response to exercise, we often refer to athletes with expiratory flow limitation as 'flow maximizers' rather than flow limited.
Fig. 1 The flow signal during disconnection in case of expiratory flow limitation (at the top) or no expiratory flow limitation (at the bottom).
During expiration when expiratory flow was limited, the volume change of the trunk led the volume exhaled at the mouth in time and was of greater amplitude.
However, a recent model in normal individuals showed that peak expiratory flow was limited by mechanical properties of the lung (in accordance with the wave speed mechanism), and not by muscle strength [ 26].
Direct assessment of lung effects has generally been limited to measurement of peak expiratory flow rate (PEFR) diaries, which, like any self-administered test involving writing down numerical values, may be prone to subjective bias, end-digit preference and auto-correlation.
Flow limitation occurs when the expiratory flow cannot be increased despite the raise of alveolar pressure, as usually occurs during the increase of an expiratory effort [1].
Tidal expiratory flow limitation (EFL) occurs when an increase in transpulmonary pressure causes no increase in resting expiratory flow.
