Differences in Clinical Tests for Assessing Lateral Epicondylitis Elbow in Adults Concerning Their Physical Activity Level: Test Reliability, Accuracy of Ultrasound Imaging, and Relationship with Energy Expenditure

Background: Physical activity (PA) can generate physical stress on the musculoskeletal system. Thus, the aim of the current study was to assess the influence of the level of physical activity on clinical tests used in the diagnosis of lateral epicondylitis in adults, intertest reliability and accuracy based on ultrasound imaging, and relationship with energy expenditure. Methods: 102 adults with lateral epicondylitis were assessed via an International Physical Activity Questionnaire and divided according to PA level: low (n = 19) moderate (n = 42) or high (n = 41). Pain (visual analog scale), Cozen’s and Mill’s clinical tests and ultrasound exams were performed. Results: The Cozen’s and Mill’s tests differed among PA levels. Excellent reliability was found for Mill’s test for PA levels and the ultrasound exam (low ICC = 1.0, moderate ICC = 0.82 and high ICC = 0.99). Good reliability was found for Cozen’s test (low ICC = 0.80, moderate ICC = 0.74 and high ICC = 0.73), but with significant differences between the ultrasound exams. The Cozen’s and Mill’s clinical tests had no relationship to the level of energy expenditure for PA levels. Conclusion: Mill’s test was reliable and accurate for the PA levels. Intertest reliability was poor for the PA levels. Mill’s test proved to be accurate based on the ultrasound exam. The pain caused by the tests was not related to the level of energy expenditure.