Exercise Sensations During Moderate-Intensity Heart-Rate-Clamped Cycling in Graded Hypoxia: A Qualitative Approach

To explore how graded hypoxia affects perceptual sensations during heart-rate (HR) -clamped cycling using qualitative methods.

Sixteen trained males cycled for 60 minutes on separate visits, with their HR clamped at 80% of their first ventilatory threshold across simulated altitudes of 2500 m, 3000 m, 3500 m, and 4000 m and in normoxia. After each session, an ∼10-minute structured interview was conducted to gather insights into participants' perceptions of the exercise under each condition. Interview transcripts were analyzed for key themes, which were presented in a pen profile.

At 4000 m, 5 participants perceived light-headedness and 2 had difficulty focusing, which were not experienced at lower altitudes. Difficulty breathing increased progressively with hypoxic severity, from 1 report in normoxia to 9 at 4000 m. Limb discomfort was consistently reported across all conditions.

Despite comparable physiological responses during HR-clamped cycling, hypoxia severity influenced selected perceived sensations (ie, difficulty focusing, difficulty breathing, and light-headedness). These effects should be considered when selecting the desired hypoxic severity for HR-clamped cycling.