Physical fitness assessment and its association with quality of life in people with firbromialgia

Abstract

Fibromyalgia is a disorder of unknown etiology, characterized by widespread chronic pain and multiple comorbidities. Fibromyalgia has a larger impact on the physical function and health-related quality of life (HRQoL) of those with the condition. Physical fitness seems to be closely related to symptomatology and fibromyalgia severity. Indeed some physical fitness tests have been demonstrated to discriminate between the presence or absence of fibromyalgia. The overall objective of the present Doctoral Thesis has been to analyse the validity, reliability and feasibility of instruments to assess physical fitness in women with fibromyalgia, as well as to provide age-specific reference values of physical fitness and to compare them with age-matched controls. Additionally, the association of physical fitness with HRQoL was assessed in this population. To address these aims, four studies were conducted in the context of a Pilot project and the main research project (the alÁndalus project). Study I was carried out with 100 women with fibromyalgia that participated in the Pilot project. Study II was performed with 101 women with fibromyalgia of the Pilot project (reliability sub-study), plus 415 women with fibromyalgia and 195 control participants of the al-Ándalus project (validity sub-study). Study III involved 489 people with fibromyalgia (including 21 men) and 415 controls (including 55 men), and Study IV included 466 women with fibromyalgia, all belonging to the al-Ándalus project (main project). Physical fitness was assessed with the Senior Fitness Test battery and handgrip test. Self-reported physical fitness was measured with the International FItness Scale (IFIS) and HRQoL was measured with the 36-item Short-Form Health Survey. The main findings and conclusions of this Doctoral Thesis were: i) The Senior Fitness Test battery, and the handgrip test demonstrated good reliability in the measurement of physical fitness in women with fibromyalgia. These tests were quick and easy to administer, and as such feasible to use with this population; ii) The IFIS was demonstrated to be a useful tool to identify women with fibromyalgia who had very low physical fitness and distinguish them from those with higher physical fitness levels. Furthermore, the IFIS has demonstrated moderate test-retest reliability in women with fibromyalgia; iii) Physical fitness levels of people with fibromyalgia from Andalusia are very low in comparison with age-matched healthy controls; iv) High physical fitness was consistently associated with better HRQoL in women with fibromyalgia. Muscle strength was independently associated with the physical component of HRQoL, whereas flexibility and cardiorespiratory fitness were independently associated with the mental component. The results of this Doctoral Thesis have provided valid, reliable and feasible tools to measure physical fitness in people with fibromyalgia, as well as, age-specific reference values of physical fitness of a geographically representative sample of the south of Spain. Results also suggest that a better physical fitness could contribute to a better HRQoL in women with fibromyalgia. Future intervention studies, based on the results of this Doctoral Thesis, will increase the knowledge about the preventive and therapeutic value of exercise and physical fitness in this population.