title: Physical working capacity at fatigue threshold (PWCFT) is associated with sarcopenia-related body composition and measures of functionality in older adults.
abstract: The relationship between PWCFT and common measures used to assess sarcopenia in older adults were examined. Fifty-eight older adults [age: 71.1 ± 6.2 years; body mass index (BMI): 28.0 ± 5.4 kg/m(2)] completed the testing procedures. Sarcopenia-related body composition was measured by dual-energy X-ray absorptiometry and participants performed a discontinuous cycle ergometry test to determine PWCFT. Functionality assessments included maximal isometric grip strength (GRIP) and sit-to-stand (STS) repetitions in 30s. Muscle quality (MQ) was defined as GRIP relative to appendicular lean soft tissue (ALM), while skeletal muscle index (SMI) was defined as ALM/height(2). Pearson correlations were used to examine the relationships among dependent variables. PWCFT showed significant relationships with ALM (r=0.57), SMI (r=0.47), body fat percentage (BF%) (r=-0.50), GRIP (r=0.49), and STS (r=0.44). For follow-up analyses, study participants were categorized into low sarcopenia risk (n=31) or high sarcopenia risk (n=27) groups by SMI. Sarcopenia risk was associated with PWCFT [odds ratio (OR): 1.051, 95% confidence interval (CI): 1.016-1.087] and STS (OR: 1.305, CI: 1.060-1.607), but not GRIP (OR: 1.098, CI: 0.989-1.218). Using receiver-operator characteristic curve analysis, both PWCFT [area under the curve (AUC): 0.737, CI: 0.608-0.866, optimal cutoff: 37.5 W] and STS (AUC: 0.749, CI: 0.623-0.874, optimal cutoff: 12.5 repetitions) showed discriminative ability with regard to sarcopenia risk. The current data suggest that the neuromuscular fatigue threshold, as measured by PWCFT, is related to measures of body composition and function in older adults.
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Nadia S
authors.initials: NS
authors.lastname: Emerson
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States. Electronic address: david.fukuda@ucf.edu.
authors.forename: David H
authors.initials: DH
authors.lastname: Fukuda
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Stout
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Robinson
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: William P
authors.initials: WP
authors.lastname: McCormack
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Tyler C
authors.initials: TC
authors.lastname: Scanlon
authors.affiliation: University of Central Florida Health Center, P.O. Box 163333, University of Central Florida, Orlando, FL 32816, United States.
authors.forename: Ashlee M
authors.initials: AM
authors.lastname: Warren
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Wells
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Gonzalez
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Gerald T
authors.initials: GT
authors.lastname: Mangine
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Maren S
authors.initials: MS
authors.lastname: Fragala
authors.affiliation: Institute of Exercise Physiology and Wellness, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, United States.
authors.forename: Jay R
authors.initials: JR
authors.lastname: Hoffman
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015992:Body Mass Index; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D012306:Risk; D055948:Sarcopenia / Q000503:physiopathology*
keywords: Aging; Disability; Neuromuscular function; Skeletal muscle index