Identifying predictors of upper extremity muscle elasticity with healthy aging.

Ultrasound shear wave elastography (SWE) can provide accurate in vivo measurements of the effect of advanced age on muscle elasticity. Our objective was to determine whether passive muscle elasticity was influenced by posture, chronological age, sex, body mass index, and clinical measures of upper extremity function for healthy adults. The dominant arm of 33 male and 33 female participants (ranging from 20 to 89 years old) was examined using a Supersonic Imagine Aixplorer ultrasound SWE system. The mean and standard deviation of shear wave velocity (SWV) was measured from elastography maps for five upper extremity muscles examined at rest: anterior deltoid (AD), biceps brachii (BB), clavicular (CL) and sternocostal (SC) region of the pectoralis major and middle trapezius (MT). Linear mixed models for each muscle were used to assess how SWV was influenced by humeral elevation, chronological age, sex, BMI and three functional measures. All significances are reported at α = 0.05. Humeral elevation influenced shear wave velocity at a statistically significant level for AD, BB, SC and MT (all p < 0.047). Chronological age was a significant predictor of mean SWV for the sternocostal region of the pectoralis major and the middle trapezius (both p < 0.03). These same muscles were also less homogenous (based on their standard deviations) with increased age, particularly for female participants. Performance-based functional assessments of the upper extremity were predictors of mean SWV for the clavicular region of the pectoralis major (all p < 0.04). These results suggest ultrasound SWE has potential utility for assessing age-related changes to muscle elasticity, but these associations were muscle-dependent.

Psychometric Properties of the Dance Functional Outcome Survey (DFOS): Reliability, Validity, and Responsiveness.

BACKGROUND: There are no outcomes measures that focus on the unique functional requirements of dancers. OBJECTIVES: To evaluate test-retest reliability, internal consistency, construct validity, sensitivity, and responsiveness of the Dance Functional Outcome Survey (DFOS) in professional and preprofessional adult dancers. METHODS: This prospective cohort study examined test-retest reliability of the DFOS in 198 healthy and injured dancers over 2 weeks, using intraclass correlation coefficients (ICC2,1). In a sample of 725 healthy and injured dancers, the following were examined: (1) construct validity, by comparing the DFOS to the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) using Pearson correlations; (2) exploratory factor analysis and internal consistency; and (3) sensitivity, by generating receiver operating characteristic curves and determining area under the curve (AUC). In a subgroup of 47 injured dancers, we determined internal responsiveness across 4 time points using repeated-measures analysis of variance (P<.05). Injured dancers' scores were analyzed for floor and ceiling effects. RESULTS: The DFOS demonstrated high test-retest reliability (ICC≥0.93). Single-factor loading in exploratory factor analysis supported unidimensionality of the scale, with high internal consistency (α = .96). The DFOS total score and activities-of-daily-living (ADL) and dance technique subscores had strong construct validity compared with scores on the SF-36 physical component summary (r≥0.77). This study found excellent sensitivity, with high AUC values (AUC≥0.91). There were significant differences across time for DFOS scores (P<.001), demonstrating responsiveness to change. There were no floor or ceiling effects. CONCLUSION: The DFOS demonstrates acceptable psychometric performance as an outcome and screening measure for dancers. The DFOS is a useful tool to monitor both healthy state and functional limitation following lower extremity or low back injury in adult ballet and modern dancers. J Orthop Sports Phys Ther 2019;49(2):64-79. Epub 27 Jul 2018. doi: 10.2519/jospt.2019.8247.