This study aimed to analyse the association between socioeconomic status (SES) and fatness and fitness in preschoolers. 2,638 preschoolers (3–5 years old; 47.2% girls) participated. SES was estimated from the parental educational and occupational levels, and the marital status. Fatness was assessed by body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR). Physical fitness components were assessed using the PREFIT battery. Preschoolers whose parents had higher educational levels had lower fatness (P < 0.05). BMI significantly differed across occupational levels of each parent (P < 0.05) and WHtR across paternal levels (P = 0.004). Musculoskeletal fitness was different across any SES factor (P < 0.05), except handgrip across paternal occupational levels (P ≥ 0.05). Preschoolers with high paternal occupation had higher speed/agility (P = 0.005), and those with high or low maternal education had higher VO₂max (P = 0.046). Odds of being obese and having low musculoskeletal fitness was lower as SES was higher (P < 0.05). Those with married parents had higher cardiorespiratory fitness than single-parent ones (P = 0.010). School-based interventions should be aware of that children with low SES are at a higher risk of obesity and low fitness already in the first years of life.

We aimed to analyse the longitudinal association between physical fitness (PF) and body composition (BC) with a metabolic risk score (Met4) in children and adolescents and to elucidate whether the association between PF and Met4 differs when using relativized or absolute fitness variables. A total of 188 children (86 females) and 195 adolescents (97 females) were included. Cardiorespiratory fitness (CRF) was determined by the 20-m shuttle run test, and muscular fitness (MF) was determined by hand grip and standing long jump tests. Height and weight were measured, and the body mass index (Kg/m²) was calculated. Triceps and subscapular skinfolds were assessed to compute body fat percentage. Met4 was computed from systolic blood pressure, triglycerides, high-density lipoprotein cholesterol, and glucose levels. Relative CRF was longitudinally and negatively associated with Met4 in female children (β = −0.031, p = 0.025), while absolute CRF was positively associated with Met4 in male children and adolescents (β = 0.000, p < 0.05). Relative upper and lower-body MF were longitudinally and negatively associated with Met4 in female adolescents (β = −1.347, β = −0.005, p < 0.05), while absolute lower-body MF was positively associated with Met4 in male children (β = 0.000, p = 0.019). BC was longitudinally and positively associated with Met4 in male children (β-ranging from 0.011 to 0.055, all p < 0.05) and male adolescents (β-ranging from 0.011 to 0.046, all p < 0.05).  Conclusion: BC is more strongly associated with Met4 than PF in children and adolescents. An optimal body weight status should be considered the main objective of health-promoting programs at childhood and adolescence. Furthermore, the way of expressing the fitness variables determines the direction of the association with Met4. What is Known:• Physical fitness is an important health indicator in children and adolescents, with great amount of previous evidence supporting the preventive role of maintaining optimal levels of both cardiorespiratory and muscular fitness for future cardiometabolic issues. What is New:• The way of reporting physical fitness variables can affect the associations between physical fitness features and cardiometabolic outcomes. Since body composition variables have a great impact on both physical fitness and cardiometabolic health, relativizing physical fitness performance by body composition could lead to erroneous conclusions.

Introduction: We aimed to analyze the cross‐sectional and longitudinal association of physical activity (PA) levels and PA patterns with metabolic syndrome score (MetS) in children and adolescents.Methods: A total of 175 children (82 females) and 188 adolescents (95 females) were included. Objective PA levels and patterns were determined by accelerometry. MetS was computed from waist circumference, systolic blood pressure, triglycerides, high‐density lipoprotein cholesterol, and glucose levels. Different linear regression models were implemented to examine the associations of PA with MetS.Results: Vigorous PA, moderate‐vigorous PA, number of bouts per day in 10 min (N10), and total time in bouts per day in 10 min (T10) were negatively associated with MetS in male children and adolescents at cross‐sectional level (β ranging from −0.005 to −0.164, all p < 0.05). Total time in bouts per day in 20 min in male children, and vigorous PA and N10 in female children were longitudinally and negatively associated with MetS (β ranging from −0.011 to −0.247, all p < 0.05).Conclusions: Associations of PA and MetS were observed at cross‐sectional level in males and longitudinally in female children. The associations in PA patterns were found when patterns were grouped into bouts of 10 min. Therefore, for future studies of PA with health markers in the pediatric population, it would be advisable to choose bouts of shorter duration.

Background: Active commuting could provide an opportunity to counteract unhealthy behaviours, such as insufficient levels of Physical Activity (PA) and sedentary behaviour, which are major health problems in the university population. The aims of this study were to describe and compare self-reported and device-measured in commuting behaviours, PA, and sedentary behaviour in both trips (to and from university) by mode of commuting per weekday, and to identify associations between self-reported and device-measured of commuting behaviours, PA, and sedentary behaviour. Methods: After inclusion criteria, a total of 63 students (65.1% women) from a public university in Cádiz, Spain, participated in this study. Self-reported and device-measured information was used. Results: Commuting time, distance, and speed were lower in active commuters than public and private commuters in both trips (to and from university) (all, p < 0.001). Commuting energy expenditure per min was higher in active commuters than public and private commuters (all, p < 0.001). Active commuters presented significant differences (p < 0.05) with public and private commuters in all PA levels and sedentary behaviour in both trips (to and from university). Conclusions: Active commuting involved the highest levels of energy expenditure per min and could contribute 44% of the weekly PA recommendation for health benefits in university students.

Background/Objectives: The longitudinal associations between different modalities of sedentary behaviors (SBs) and sedentary patterns (SPs) with metabolic syndrome (MetS) in children and adolescents are unclear. We aimed to analyze the cross-sectional and longitudinal (2-year follow-up) association between SB and SP with the MetS score in Spanish children and adolescents. Methods: 76 children (34 females) and 186 adolescents (94 females) were included for SB analyses, and 175 children (82 females) and 188 adolescents (95 females) for SP. Children and adolescents were aged 6–11.9 years and 12–17.9 years, respectively. SB were assessed by a self-reported questionnaire and SP were determined by accelerometry. The MetS score was computed from the waist circumference, systolic blood pressure, triglycerides, high-density lipoprotein cholesterol, and glucose levels. Different linear regression models were implemented to examine cross-sectional, longitudinal, and change associations of SB and SP with MetS. Results: Total daily SB, educative daily SB, and mean SB were longitudinal and inversely associated with MetS (β = −0.001, all p < 0.05) in male adolescents, while other daily SB was longitudinal and inversely associated with MetS (β = −0.002, all p < 0.05) in female adolescents. Changes in screen and other daily SB were directly associated with MetS in female adolescents (β = 0.001 to 0.002, all p < 0.05). In contrast, changes in educative daily SB were inversely associated with MetS in female adolescents (β = −0.001, all p < 0.05). Conclusions: Few associations between SB modalities and the MetS score were found, mainly in adolescents and often in unexpected directions. In male adolescents, total and educative daily SB were negatively associated with MetS. In female adolescents, other daily SB and changes in educative daily SB showed negative associations, while changes in screen-based and other daily SB were positively associated with MetS. No associations were found between SP and MetS. Given the low evidence available to date, more longitudinal studies analyzing SB and SP simultaneously are needed to reach solid conclusions.

Muscular fitness is a key component of health and athletic performance, and isometric strength is a widely used indicator. This study reports an agreement-based validation of the Isometric Strength Measurement Device (ISOMETRO) for upper-limb isometric tension measurements under controlled laboratory conditions. Twenty-one healthy young amateur rock climbers (11 men and 10 women) performed four upper-limb tensile tests (shoulder adduction at 90°, shoulder adduction at 60°, shoulder extension at 90°, and elbow extension at 90°). Agreement with an independent criterion device was evaluated using a force plate, while a series-connected load cell was used as an internal consistency check of the measurement chain. Linear mixed-effects models showed that ISOMETRO strongly predicted force plate values (β = 0.999, SE = 0.002, p < 0.001), with a marginal R² > 0.99. Bland–Altman analysis indicated negligible bias (−0.08 N) and narrow limits of agreement (−4.97 to 4.81 N), and concordance was excellent (CCC ≥ 0.996). The series-connected load cell comparison also showed near-unity agreement (β = 0.998, SE = 0.003, p < 0.001), supporting internal measurement chain integrity. These findings support excellent agreement between ISOMETRO and force plate measurements for upper-limb tensile isometric testing along the vertical axis in young amateur rock climbers under controlled laboratory conditions. However, given the specific sample characteristics and the strictly vertical laboratory configuration, these results should not be generalized to other populations, joint angles, force directions, or non-laboratory environments without further validation. Further studies are needed to confirm performance in more diverse contexts and to establish reliability for repeated-measurement applications.