Clinician-friendly physical performance tests in athletes part 3: a systematic review of measurement properties and correlations to injury for tests in the upper extremity.

OBJECTIVE: In parts 1 and 2 of this systematic review, the methodological quality as well as the quality of the measurement properties of physical performance tests (PPTs) of the lower extremity in athletes was assessed. In this study, part 3, PPTs of the upper extremity in athletes are examined. METHODS: Database and hand searches were conducted to identify primary literature addressing the use of upper extremity PPTs in athletes. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed and the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist was used to critique the methodological quality of each paper. The Terwee Scale was used to analyse the quality of the measurement properties of each test. RESULTS: 11 articles that examined 6 PPTs were identified. The 6 PPTs were: closed kinetic chain upper extremity stability test (CKCUEST), seated shot put (2 hands), unilateral seated shot put, medicine ball throw, modified push-up test and 1-arm hop test. Best evidence synthesis provided moderate positive evidence for the CKCUEST and unilateral seated shot put. Limited positive evidence was available for the medicine ball throw and 1-arm hop test. CONCLUSIONS: There are a limited number of upper extremity PPTs used as part of musculoskeletal screening examinations, or as outcome measures in athletic populations. The CKCUEST and unilateral seated shot put are 2 promising PPTs based on moderate evidence. However, the utility of the PPTs in injured populations is unsubstantiated in literature and warrants further investigation.

Giving science the finger-is the second-to-fourth digit ratio (2D:4D) a biomarker of good luck? A cross sectional study.

OBJECTIVES: To explore whether random chance, weak research methodology, or inappropriate reporting can lead to claims of statistically significant (yet, biologically meaningless) biomarker associations, using as a model the relation between a common surrogate of prenatal testosterone exposure, second-to-fourth digit ratio (2D:4D), and a random indicator of good luck. DESIGN: Cross sectional study. SETTING: University sports performance laboratory in the United States. Data were collected from May 2015 to February 2017. PARTICIPANTS: 176 adults (74 women, 102 men), including university students, faculty, and staff with no history of injuries, disease, or medical conditions that would affect digit length. MAIN OUTCOME MEASURES: 2D:4D, body composition parameters potentially influenced by androgens (bone mineral content, bone mineral density, body fat percentage), and good luck (using poker hands from randomly selected playing cards as a surrogate). RESULTS: 2D:4D significantly correlated with select body composition parameters (Spearman's r s range -0.26 to 0.23; P<0.05), but the correlations varied by sex, participant hand measured, and the method of measuring 2D:4D (by photocopy or radiography). However, the strongest correlation observed was between right hand 2D:4D in men measured by radiograph and poker hand rank (r s=0.28, P=0.004). CONCLUSIONS: Greater prenatal exposure to testosterone, as estimated by a lower 2D:4D, significantly increases good luck in adulthood, and also modulates body composition (albeit to a lesser degree). While these findings are consistent with a wealth of research reporting that 2D:4D is related to many seemingly disparate outcomes, they are not meant to provide confirmatory evidence that 2D:4D is a universal biomarker of nearly everything. Instead, the associations between 2D:4D and good luck are simply due to chance, and provide a "handy" example of the reproducibility crisis within medical and scientific research. Biologically sound hypotheses, pre-registration of trials, strong methodological and statistical analyses, transparent reporting of negative results, and unbiased interpretation of data are all necessary for biomarker studies and other areas of clinical research.