The purpose of this study was to analyze the criterion‐related validity and the reliability of the standing long jump test (SLJ) for evaluating the lower‐body explosive muscular strength in adults. A total of 410 adults participated in this study. Sociodemographic, anthropometric measurements, laboratory lower‐body muscular strength tests, and the field‐based SLJ were performed. In validity analysis, stepwise regression analysis showed that maximal horizontal power, sex, percentage of body fat, maximal horizontal force, and lean mass were significantly associated with the SLJ distance (R² = 0.78; p < 0.001). Reliability analysis showed significant differences between test–retest in the SLJ test, with an overestimation of the second measurement compared to the first [12.14 ± 14.46 cm, intraclass correlation coefficient (ICC) = 0.94 (0.75–0.97), p < 0.001; Cohen's d = 0.31]. The coefficient of variation (CV) was 7.06% and the minimal detectable change (MDC₉₀) was 29 cm. After a learning period, higher reliability values were found [0.45 ± 1.04 cm, ICC = 1.00 (0.99–1.00); p = 0.001; CV = 0.53 %; MDC₉₀ = 1 cm]. The SLJ test may be a valid tool to assess lower‐body explosive muscular strength in the adult population. A learning period may be necessary to provide reliability on the SLJ test.

Motor fitness and flexibility have been linked to several health issues. We aimed to investigate the predictive validity of motor fitness and flexibility tests in relation to health outcomes in adults and older adults. Web of Science and PubMed databases were screened for studies published from inception to November 2020. Two authors systematically searched, evaluated, and extracted data from identified original studies and systematic reviews/meta-analysis. Three levels of evidence were constructed: strong, moderate, and limited/inconclusive evidence. In total, 1182 studies were identified, and 70 studies and 6 systematic reviews/meta-analysis were summarized. Strong evidence indicated that (i) slower gait speed predicts falls and institutionalization/hospitalization in adults over 60 years old, cognitive decline/impairment over 55 years old, mobility disability over 50 years old, disability in instrumental activities of daily living (IADL) over 54 years old, cardiovascular disease risk over 45 years old, and all-cause mortality over 35 years old; (ii) impaired balance predicts falls and disability in IADL/mobility disability in adults over 40 years old and all-cause mortality over 53 years old; (iii) worse timed up&go test (TUG) predicts falls and fear of falling over 40 years old. Evidence supports that slower gait speed, impaired balance, and worse TUG performance are significantly associated with an increased risk of adverse health outcomes in adults.

The aim of the present study was to investigate the existence of a relative age effect (RAE) on physical fitness of preschoolers. Anthropometry and physical fitness were assessed in 3147 children (3–5 years old) using the PREFIT battery. Based on the birth year, participants were divided into 3year groups (3-, 4- and 5-years). Within each year group, 4quarter groups were created: quarter 1, preschoolers born from January to March; quarter 2, from April to June; quarter 3, from July to September; quarter 4, from October to December. The MANCOVA analysis revealed a main effect of year group (Wilks’ λ = 0.383; F_10,5996 = 369.64; p < 0.001, η_p² = 0.381) and of quarter (Wilks’ λ = 0.874; F_15,8276.6 = 27.67; p < 0.001; η_p² = 0.044) over the whole battery of tests. To the best of our knowledge, this is the first study to report the existence of RAE at the preschool stage. In general, performance improved as the relative age increased (i.e., those born in quarter 1 performed better than those in the other quarters). Individualization strategies should be addressed within the same academic year not only in elementary or secondary years but also in preschoolers.