Faculty Collaboration Database

Sex Differences in Arm Muscle Fatigability With Cognitive Demand in Older Adults. Clin Orthop Relat Res 2015 Aug;473(8):2568-77

Date

02/26/2015

Pubmed ID

25712862

Pubmed Central ID

PMC4488210

DOI

10.1007/s11999-015-4205-1

Scopus ID

2-s2.0-84934434676 (requires institutional sign-in at Scopus site)   19 Citations

Abstract

BACKGROUND: Muscle fatigability can increase when a stressful, cognitively demanding task is imposed during a low-force fatiguing contraction with the arm muscles, especially in women. Whether this occurs among older adults (>60 years) is currently unknown.

QUESTIONS/PURPOSES: We aimed to determine if higher cognitive demands, stratified by sex, increased fatigability in older adults (>60 years). Secondarily, we assessed if varying cognitive demand resulted in decreased steadiness and was explained by anxiety or cortisol levels.

METHODS: Seventeen older women (70±6 years) and 13 older men (71±5 years) performed a sustained, isometric, fatiguing contraction at 20% of maximal voluntary contraction until task failure during three sessions: high cognitive demand (high CD=mental subtraction by 13); low cognitive demand (low CD=mental subtraction by 1); and control (no subtraction).

RESULTS: Fatigability was greater when high and low CD were performed during the fatiguing contraction for the women but not for the men. In women, time to failure with high CD was 16±8 minutes and with low CD was 17±4 minutes, both of which were shorter than time to failure in control contractions (21±7 minutes; high CD mean difference: 5 minutes [95% confidence interval {CI}, 0.78-9.89], p=0.02; low CD mean difference: 4 minutes [95% CI, 0.57-7.31], p=0.03). However, in men, no differences were detected in time to failure with cognitive demand (control: 13±5 minutes; high CD mean difference: -0.09 minutes [95% CI, -2.8 to 2.7], p=1.00; low CD mean difference: 0.75 minutes [95% CI, -1.1 to 2.6], p=0.85). Steadiness decreased (force fluctuations increased) more during high CD than control. Elevated anxiety, mean arterial pressure, and salivary cortisol levels in both men and women did not explain the greater fatigability during high CD.

CONCLUSIONS: Older women but not men showed marked increases in fatigability when low or high CD was imposed during sustained static contractions with the elbow flexor muscles and contrasts with previous findings for the lower limb. Steadiness decreased in both sexes when high CD was imposed.

CLINICAL RELEVANCE: Older women are susceptible to greater fatigability of the upper limb with heightened mental activity during sustained postural contractions, which are the foundation of many work-related tasks.

Author List

Pereira HM, Spears VC, Schlinder-Delap B, Yoon T, Harkins A, Nielson KA, Hoeger Bement M, Hunter SK

Authors

April Harkins PhD Assistant Professor in the Clinical Laboratory Science department at Marquette University
Marie Hoeger Bement MPT,PhD Associate Professor in the Physical Therapy department at Marquette University
Kristy Nielson PhD Professor in the Psychology department at Marquette University

MESH terms used to index this publication - Major topics in bold

Age Factors
Aged
Aging
Anxiety
Arterial Pressure
Biomechanical Phenomena
Cognition
Female
Heart Rate
Humans
Hydrocortisone
Isometric Contraction
Male
Mathematical Concepts
Middle Aged
Muscle Fatigue
Muscle, Skeletal
Risk Factors
Saliva
Sex Factors
Stress, Psychological
Time Factors
Torque
Upper Extremity