Abstract
Background: We compared acute psychophysiological responses with a single intermittent hypoxic exposure (IHE)/normoxic exposure trial with varying cycle lengths in adults with obesity. Materials and Methods: Eight obese adults (body mass index = 33.0 ± 2.2 kg/m2) completed three 60-minute IHE trials (passive seating), separated by 7 days. Trials comprised 30-minute hypoxia/30-minute normoxia (inspired oxygen fraction = 12.0%/20.9%) over Short (15 × 2/2 minutes), Medium (10 × 3/3 minutes), and Long (5 × 6/6 minutes) hypoxic/normoxic cycles and a control trial (60-minute normoxia). Results: Arterial oxygen saturation was lower during hypoxic periods of Long versus Medium and Short trials (90.1% vs. 93.0% and 94.2%; p = 0.02 and p = 0.05), with no differences between Short and Medium. Prefrontal cortex oxygenation was lower (-5.1%) during all IHE interventions versus control (p < 0.02), independent of cycle length. Perceived breathlessness was unaffected during IHE but increased 15 minutes after exposure versus baseline (+34%; p = 0.04). Breathlessness was lowest after Short versus control from 15 to 60 minutes (-7%; p = 0.01). Conclusions: When implementing IHE, greater desaturation is observed during longer compared with shorter hypoxic/normoxic cycles in adults with obesity. However, IHE tends to be better tolerated perceptually with shorter rather than longer cycles.
Highlights
In the UK, ~26% of adults are overweight and~35% obese (BMI = 30–40 kg/m-2) (Baker, 2018)
Arterial oxygen saturation was lower during hypoxic periods of Long vs. Medium and
Perceived breathlessness was unaffected during intermittent hypoxic/normoxic exposure (IHE), but increased 15-min after exposure vs. baseline (+34%; p = 0.04)
Summary
In the UK, ~26% of adults are overweight (body mass index [BMI] = 27–29.9 kg/m-2) and. To reduce body weight and improve health in obese populations, lifestyle interventions (i.e., dietary manipulation, physical activity) have been implemented, yet with low adherence and success (Forman & Butryn, 2015). There is an urgent need for new strategies to reduce obesity prevalence and improve the health and wellbeing of this population. Workman and Basset (2012) found increased energy expenditure in overweight males immediately following one continuous resting 3-h session at a target SpO2 of 85% versus normoxia. Continuous hypoxic exposure (several hours) versus normoxia may exacerbate sympathetic nervous system activity, raising the risk of elevated blood pressure, tachycardia and rate pressure product in ‘at-risk’ individuals (White et al., 1985; Wulsin et al, 2017). We compared acute psycho-physiological responses to a single intermittent hypoxic/normoxic exposure (IHE) trial with varying cycle lengths in adults with obesity. iew ev
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