Normative Parameters of Gastrocnemius Muscle Stiffness and Associations with Patient Characteristics and Function.

BACKGROUND: Quantifying muscle stiffness may aid in the diagnosis and management of individuals with muscle pathology. Therefore, the primary purpose of this study was to establish normative parameters and variance estimates of muscle stiffness in the gastrocnemius muscle in a resting and contracted state. A secondary aim was to identify demographic, anthropometric, medical history factors, and biomechanical factors related to muscle stiffness. METHODS: Stiffness of the gastrocnemius muscle was measured in both a resting and contracted state in 102 asymptomatic individuals in this cross-sectional study. Differences based on muscle state (resting vs contracted) and sex (female vs male) were assessed using a 2 X 2 analysis of variance (ANOVA). Associations between muscle stiffness and sex, age, BMI, race, exercise frequency, exercise duration, force production, and step length were assessed using correlation analysis. RESULTS: Gastrocnemius muscle stiffness significantly increased from a resting to a contracted state [mean difference: 217.5 (95% CI: 191.3, 243.8), p < 0.001]. In addition, muscles stiffness was 35% greater for males than females in a resting state and 76% greater in a contracted state. Greater muscle stiffness in a relaxed and contracted state was associated with larger plantarflexion force production (r = .26, p < 0.01 and r = .23, p < 0.01 respectively). CONCLUSION: Identifying normative parameters and variance estimates of muscle stiffness in asymptomatic individuals may help guide diagnosing and managing individuals with aberrant muscle function. LEVEL OF EVIDENCE: 2b Individual Cohort Study. CLINICAL RELEVANCE: What is known about the subject: Muscle stiffness has been shown to be related to individuals with pathology such as Achilles tendinopathy; however, research is sparse regarding normative values of muscle stiffness. Measuring muscle stiffness may also be a way to potentially predict individuals prone to injury or to monitor the effectiveness of management strategies.What this study adds to existing knowledge: This study establishes defined estimates of muscle stiffness of the gastrocnemius in both a relaxed and contracted state in healthy individuals. Myotonometry measures of muscle stiffness demonstrated an increase in stiffness during contraction that varies by sex. Greater gastrocnemius muscle stiffness was associated with increased plantarflexion force production.

Improving work outcomes of dysthymia (persistent depressive disorder) in an employed population.

OBJECTIVE: To test the effectiveness of a work-focused intervention (WFI) on the work outcomes of employed adults with dysthymia. METHOD: This subgroup analysis from a randomized controlled trial compares an initial sample of 167 employees (age: ≥45 years), screened for dysthymia using the PC-SAD without current major depressive disorder randomized to WFI (n=85) or usual care (UC) (n=82). Study sites included 19 employers and five additional organizations. Telephone-based WFI counseling (eight, twice monthly 50-min sessions) provided work coaching and modification, care coordination and cognitive behavioral therapy. Adjusted mixed effects models compared the WFI vs. UC group preintervention to 4-month postintervention change in at-work limitations measured by the Work Limitations Questionnaire. Secondary outcome analysis compared the change in self-reported absences and depression symptom severity (Patient Health Questionnaire PHQ-9 scores). RESULTS: Work productivity loss scores improved 43.0% in the WFI group vs. 4.8% in UC (difference in change: P<.001). Absence days declined by 58.3% in WFI vs. 0.0% in UC (difference in change: P=.09). Mean PHQ-9 depression symptom severity declined 44.2% in WFI vs. 5.3% in UC (difference in change: P<.001). CONCLUSION: At 4 months, the WFI was more effective than UC on two of the three outcomes. It could be an important mental and functional health improvement resource for the employed dysthymic population.

The reliability and validity of the Caregiver Work Limitations Questionnaire.

OBJECTIVE: To test a new Caregiver Work Limitations Questionnaire (WLQ). On the basis of the original WLQ, this new survey instrument assesses the effect of caregiving for ill and/or disabled persons on the caregiver's work performance. METHOD: A questionnaire was administered anonymously to employees of a large business services company. Scale reliability and validity were tested with psychometric methods. RESULTS: Of 4128 survey participants, 18.3% currently were caregivers, 10.2% were past caregivers, and 71.5% were not caregivers. Current caregivers were limited in their ability to perform basic job tasks between mean 10.3% and 16.8% of the time. Confirmatory factor analysis yielded a scale structure similar to the WLQ's. Scales reliabilities (the Cronbach's α) ranged from 0.91 to 0.95. CONCLUSIONS: The Caregiver WLQ is a new tool for understanding the workplace effect of caregiving.