A Profile of Physical Fitness Variables in an Out-Patient Adult Population with Narcolepsy

Abstract

Background: Narcolepsy is a disabling lifelong condition that impacts an individuals ability to regulate sleep-wake patterns. Narcolepsy can significantly impact the physical and mental wellbeing of people with narcolepsy, and has been associated with significant reductions in quality of life and physical performance. Despite physical functioning and vitality being the most affected domains of health-related quality of life in this cohort, more accurate measurements of physical performance using a suitable physical test battery have not yet been conducted.

Methods: A systematic review and meta-analysis was conducted to explore health-related quality of life in adults with narcolepsy. A cross-sectional study was conducted to assess the physical performance of adults with narcolepsy who attended the Narcolepsy Clinic in St. James s Hospital between October 2019 and March 2020. A comprehensive battery was designed to assess physical performance variables. The following variables were objectively assessed; cardiopulmonary fitness (YMCA Submaximal Bike Test), muscle strength (Dynamometry and Countermovement Jump Test), muscle endurance (ACSM Push Up Test and Wall Squat Test) and physical activity (Actigraphy). A number of questionnaires were utilised to assess health-related quality of life (Short Form 36 and Functional Outcomes of Sleep Questionnaire), symptom severity (Narcolepsy Severity Scale and Epworth Sleepiness Scale) and physical activity (Physical Activity Vital Sign) and sedentary behaviour (Sedentary Behaviour Questionnaire) of this sample. Several open-ended questions were asked to ascertain participants attitudes towards exercise and their physical performance.

Results: In total, 23 participants completed the test battery. The majority of participants were female (n=13, 56.52%). The mean age (± SD) was 31.53 (13.17) years with a range of 20-63 years observed. The majority of participants were concentrated in the 20-29 age group (n=14, 60.87%). Physical performance was generally found to be lower than age-and-gender matched normative values for cardiopulmonary fitness, physical activity and muscle strength and endurance. Symptom severity was high as measured by the Narcolepsy Severity Scale and Epworth Sleepiness Scale, and participants reported significantly reduced quality of life when compared to general population norms. Analysis of the open-ended questions provided valuable insights into the difficulties experienced with exercising in people with narcolepsy. Furthermore, an interrelationship was identified between participants physical performance, health-related quality of life and symptom severity.

Conclusion: In this sample of people with narcolepsy, physical performance was found to be markedly reduced than normative values, irrespective of participant age, gender and BMI. The chosen test battery employed in this study was largely feasible, and participants were enthusiastic and receptive towards the study. The interrelationship identified between physical performance, symptom severity and quality of life warrants further exploration of the role of physical activity and exercise in improving the physical performance in people with narcolepsy, and the influence of exercise on health-related quality of life and symptom severity in this cohort.