title: The effects of acute experimental hip muscle pain on dynamic single-limb balance performance in healthy middle-aged adults.
abstract: Middle-aged adults with painful hip conditions show balance impairments that are consistent with an increased risk of falls. Pathological changes at the hip, accompanied by pain, may accelerate pre-existing age-related balance deficits present in midlife. To consider the influence of pain alone, we investigated the effects of acute experimental hip muscle pain on dynamic single-limb balance in middle-aged adults. Thirty-four healthy adults aged 40-60 years formed two groups (Group-1: n=16; Group-2: n=18). Participants performed four tasks: Reactive Sideways Stepping (ReactSide); Star Excursion Balance Test (SEBT); Step Test; Single-Limb Squat; before and after an injection of hypertonic saline into the right gluteus medius muscle (Group-1) or ∼5min rest (Group-2). Balance measures included the range and standard deviation of centre of pressure (CoP) movement in mediolateral and anterior-posterior directions, and CoP total path velocity (ReactSide, Squat); reach distance (SEBT); and number of completed steps (Step Test). Data were assessed using three-way analysis of variance. Motor outcomes were altered during the second repetition of tasks irrespective of exposure to experimental hip muscle pain or rest, with reduced SEBT anterior reach (-1.2±4.1cm, P=0.027); greater step number during Step Test (1.5±1.7 steps, P<0.001); and slower CoP velocity during Single-Limb Squat (-4.9±9.4mms-1, P=0.024). Factors other than the presence of pain may play a greater role in balance impairments in middle-aged adults with hip pathologies.
authors.affiliation: School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia. Electronic address: a.hatton1@uq.edu.au.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Hatton
authors.affiliation: Laboratory "Movement, Interaction, Performance" (EA 4334), University of Nantes, Nantes, France. Electronic address: francois.hug@univ-nantes.fr.
authors.forename: François
authors.initials: F
authors.lastname: Hug
authors.affiliation: School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia. Electronic address: chenhuiwensarah@gmail.com.
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Chen
authors.affiliation: School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia. Electronic address: christine.reid@uqconnect.edu.au.
authors.forename: Christine
authors.initials: C
authors.lastname: Reid
authors.affiliation: School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia. Electronic address: nicole.sorensen1@uqconnect.edu.au.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Sorensen
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, Australia. Electronic address: k.tucker1@uq.edu.au.
authors.forename: Kylie
authors.initials: K
authors.lastname: Tucker
mesh_terms: D059787:Acute Pain / Q000139:chemically induced / Q000503:physiopathology*; D000328:Adult; D002081:Buttocks; D005080:Exercise Test; D005260:Female; D064368:Healthy Volunteers; D006615:Hip; D006801:Humans; D007273:Injections, Intramuscular / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal; D063806:Myalgia / Q000139:chemically induced / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D012462:Saline Solution, Hypertonic / Q000009:adverse effects
chemical_list: D012462:Saline Solution, Hypertonic
keywords: Balance performance; Hip muscle pain; Hypertonic saline; Middle-aged adults