Physical fitness, pain and fatigue in postmenopausal women with fibromyalgia : effects of strength training

Abstract

Fibromyalgia (FM) is a chronic non-inflammatory pain syndrome characterized mainly by widespread pain, fatigue and sleep disturbance. Its pathophysiology is still unknown and no curative treatment exists. Exercise training is usually recommended to persons with FM as one part of the treatment program; however, strength training has been studied very seldom in persons with FM.The purpose of this thesis was 1) to compare neuromuscular and aerobic performance, functional capacity, pain and fatigue between postmenopausal women with fibromyalgia (FMW) and healthy women (HW) and 2) to examine the acute responses of heavy resistance fatiguing loading and the effects of regular strength training on neuromuscular performance, functional capacity, pain and fatigue. The age of the subjects was 50-70 years in two different study designs (study I: FMW n=23, HW n=11; studies II-IV: FMW n=26, HW n=10). Maximal muscle strength of different muscle groups was measured. Electromyographic activity of the lower leg muscles was recorded during the strength tests. The cross-sectional area of the quadriceps femoris was measured by magnetic resonance imaging and maximal oxygen uptake by the direct bicycle ergometer test. Functional capacity was assessed by 10-meter walking speed and 10-step stair-climbing time, and self-reported physical functional capacity by the Stanford Health Assessment Questionnaire.Pain and fatigue were assessed by the visual analog scale and quality-of-life by the RAND-36 questionnaire. For the strength training intervention women with FM (studies II-IV) were randomly assigned to a training (FMT; n=13) or a non-training control (FMC; n=13) group. HW served as the training controls. FMT and HW performed supervised progressive strength training twice a week for 21 weeks. To examine acute neuromuscular responses and exercise-induced muscle pain, a heavy-resistance fatiguing protocol was performed before and after the 21-week training period. The results showed that muscle strength of the lower extremities, work load and work time in the bicycle exercise test and functional capacity were lower in the postmenopausal FMW than in HW. Muscle strength in the upper body and maximal oxygen uptake did not differ between the groups. Heavy-resistance loading at week 0 and week 21 led to comparable decreases in maximal isometric leg extension force in FMT (25% and 26%) and HW (23% and 29%). The time course of exercise-induced muscle pain after the fatiguing loading was comparable between the groups. Strength training for 21 weeks improved the maximal muscle force of different muscle groups by 13-36% in FMT and by 24-37% in HW. Functional capacity improved in FMT, but remained unchanged in HW. No changes were observed in FMC. FMT reported a minor decreasing tendency in the FM symptoms and no adverse effects of the training were observed. The present study suggests that postmenopausal FMW may have decreased muscle strength, especially in the lower extremities. The acute neuromuscular responses and the time course of muscle pain after the fatiguing loading were comparable between the groups, suggesting normal fatiguing and recovery processes in FMT. The subjects were capable of improving their neuromuscular performance markedly by regular and progressive strength training and to carry the training out safely without exacerbation of symptoms. Therefore, individually tailored strength training is a recommendable exercise mode for postmenopausal women with FM.

Heli Valkeinen vertasi väitöstyössään 50-70-vuotiaiden fibromyalgiaa sairastavien ja terveiden naisten fyysistä kuntoa sekä yksittäisen uuvuttavan kuormituksen ja voimaharjoittelujakson vaikutuksia hermo-lihasjärjestelmän voimantuotto-ominaisuuksiin, toimintakykyyn ja oireisiin. Fibromyalgia on krooninen kipuoireyhtymä, joka aiheuttaa useita oireita. Keskeisimpiä näistä ovat eri puolilla kehoa ilmenevä lähinnä lihaksistossa tuntuva kipu ja yleinen väsymys. Koska oireyhtymän syytä ei tiedetä, sen hoito keskittyy pääasiassa oireiden lievittämiseen lääkityksen, liikunnan ja erilaisten terapiamenetelmien avulla.- Fibromyalgiaa sairastavilla 50-70-vuotiailla naisilla näyttäisi olevan alentunut lihasvoima erityisesti reisilihaksissa. He voivat kuitenkin kehittää voimantuotto-ominaisuuksiaan, kuten maksimaalista lihasvoimaa, säännöllisellä voimaharjoittelulla yhtä paljon kuin terveetkin naiset. Voimaharjoittelun todettiin olevan myös turvallista näille naisille eikä se aiheuttanut oireiden pahentumista, Valkeinen kertoo. Valkeinen vertasi ensin fibromyalgiaa sairastavien 23 naisen maksimaalista lihasvoimaa, hapenottokykyä sekä toimintakykyä ja kipu- ja väsymysoireita 11 terveen naisen vastaaviin tuloksiin. Tämä tutkimus osoitti, että fibromyalgiaa sairastavilla naisilla on alentunut lihasvoima reisilihaksissa ja heikompi toimintakyky. Lisäksi polkupyöräergometritestissä työkuorma ja työaika olivat heillä heikommat kuin terveillä naisilla. Ylävartalon lihasvoimissa ei kuitenkaan havaittu eroja ryhmien välillä.