António Antunes

Background and Objectives: Adolescents’ engagement with physical activity (PA) supportive environments has mostly been examined through variable-centered approaches, with PA rather than physical fitness (PF) as the outcome. We aimed to (1) identify latent profiles of combined engagement with home-based PA equipment and activity locations among adolescents, (2) examine whether profile membership differed by age, sex, and family sociodemographic characteristics, and (3) investigate the associations between the identified profiles and PF components. Methods: This cross-sectional study included 764 adolescents (357 girls) aged 10–17 years from the population-based DESpertar project, conducted across the nine islands of the Azores archipelago, Portugal. Caregivers reported adolescents’ engagement across six indicators (small, medium, and large equipment; domestic, public, and institutional places). PF was evaluated with six field tests assessing muscular, motor, and cardiorespiratory components. Latent profile analysis, multinomial logistic regression, and multivariate regression were used. Results: Five profiles were identified: Low overall engagement (26.2%), Average overall engagement (42.8%), Equipment-oriented engagement (13.5%), Location-oriented engagement (11.4%), and High overall engagement (6.2%). Older age was associated with a lower relative likelihood of membership in all profiles compared with Low overall engagement (RRR per year 0.58–0.83). Higher parental education was associated with Average, equipment-oriented, and High overall engagement membership, and larger household size with High overall engagement membership. Compared with the Low overall profile, adolescents in the High overall profile had higher scores in all PF components, and those in the equipment-oriented profile had higher muscular and motor fitness, whereas the location-oriented engagement profile did not differ from the Low profile. Conclusions: High overall engagement and Equipment-oriented engagement profiles were generally associated with better physical fitness.

Purpose: This study aimed to analyze the shared genetic background of physical fitness tests in children. Methods: Physical fitness was assessed in 198 Portuguese twin pairs (6–18 yr old, 40% monozygotic) through 15 tests from the Eurofit and Fitnessgram test batteries. Genetic twin modeling was used to estimate the heritability of each test and the genetic correlations between them. Results: Girls performed better than boys in flexibility, whereas boys performed better than girls in cardiorespiratory endurance and muscular strength. No sex differences were found in the influence of genetic factors on the physical fitness tests or their mutual correlations. Genetic factors explained 52% (standing long jump) to 79% (sit and reach) of the individual variation in motor performance, whereas individual-specific environmental factors explained the remaining variation. Most of the tests showed modest to moderate genetic correlations. Out of all 105 genetic correlations, 65% ranged from 0.2 to 0.6 indicating that they shared from 4% to 36% of genetic variation. The correlations between individual-specific environmental factors were mostly negligible. Conclusions: Tests measuring the strength of different muscle groups showed only modest correlations, but moderate correlations were found between tests measuring explosive strength, running speed/agility, and cardiorespiratory endurance. Genetic factors explained a major portion of the variation in tests included in the Eurofit and Fitnessgram test batteries and explained the correlations between them. The modest to moderate genetic correlations indicated that there is little redundancy of tests in either Eurofit or Fitnessgram test batteries.