The Relationship between Socioeconomic Status, Family Income, and Measures of Muscular and Cardiorespiratory Fitness in Colombian Schoolchildren.

OBJECTIVE: To determine the associations between socioeconomic status (SES) and physical fitness in a sample of Colombian youth. STUDY DESIGN: Prueba SER is cross-sectional survey of schoolchildren in Bogota, Colombia. Mass, stature, muscular fitness (standing long-jump, handgrip), and cardiorespiratory fitness (20-m shuttle run) were measured in 52?187 schoolchildren 14-16 years of age. Area-level SES was categorized from 1 (very low) to 4 (high) and parent-reported family income was categorized as low, middle, or high. RESULTS: Converting measures into z scores showed stature, muscular, and cardiorespiratory fitness were significantly (z?=?0.3-0.7) below European values. Children in the mid- and high SES groups jumped significantly further than groups with very low SES. Differences were independent of sex but became nonsignificant when adjusted for anthropometric differences. Participants in the mid-SES and high-SES groups had better handgrip scores when adjusted for body dimension. There were, however, no significant between-group differences in cardiorespiratory fitness, which was strongly clustered by school and significantly greater in students from private schools. CONCLUSIONS: Area-level SES is associated with measures of muscular fitness in Colombian schoolchildren. These associations were largely explained by the large differences in body dimensions observed between SES groups. When area-level SES is considered, there was no evidence that family income influenced fitness. The clustering of outcomes reaffirms the potential importance of schools and area-level factors in promoting fitness through opportunities for physical activity. Interventions implemented in schools, can improve academic attainment; a factor likely to be important in promoting the social mobility of children from poorer families.

Association between habitual school travel and muscular fitness in youth.

OBJECTIVE: To determine whether active school travel is associated with muscular fitness, which is an emerging marker of youth health. METHODS: Handgrip strength, vertical jump and vertical jump peak power were measured in n=6829 English schoolchildren (53% males, age 12.9 ± 1.2 years) between 2007 and 2011. Participants were grouped according to self-reported habitual school travel modality. RESULTS: Cyclists had greater handgrip strength than passive travelers. Vertical jump height was greater in walkers and cyclists compared with passive travelers. Jump peak power was also higher in walkers than in the passive travel group. Compared with passive travelers, cyclists had a higher (age, sex and BMI-adjusted) likelihood of good handgrip strength (OR 1.42, 95%CI;1.14-1.76) and walkers were more likely to have good measures for vertical jump peak power (OR 1.14, 95%CI;1.00-1.29). Cyclists' likelihood of having good handgrip strength remained significantly higher when adjusted for physical activity (OR 1.29, 95%CI;1.08-1.46). CONCLUSION: Muscular fitness differs according to school travel habits. Cycling is independently associated with better handgrip strength perhaps due to the physical demands of the activity. Better muscular fitness may provide another health-related reason to encourage active school travel.

Quantification of the relative age effect in three indices of physical performance.

The relative age effect (RAE) describes the relationship between an individual's birth month and their level of attainment in sports. There is a clustering of birth dates just after the cutoff used for selection in age-grouped sports, and it is hypothesized that such relatively older sportspeople may enjoy maturational and physical advantages over their younger peers. There is, however, little empirical evidence of any such advantage. This study investigated whether schoolchildren's physical performance differed according to which quarter of the school year they were born in. Mass, stature, body mass index, cardiorespiratory fitness, strength, and power were measured in 10 to 16 year olds (n = 8,550, 53% male). We expressed test performance as age- and sex-specific z-scores based on reference data with age rounded down to the nearest whole year and also as units normalized for body mass. We then compared these values between yearly birth quarters. There were no significant main effects for differences in anthropometric measures in either sex. Girls born in the first quarter of the school year were significantly stronger than those born at other times when handgrip was expressed as a z-score. As z-scores, all measures were significantly higher in boys born in either the first or second yearly quarters. Relative to body mass, cardiorespiratory fitness was higher in boys born in the first quarter and power was higher in those born in the second quarter. The RAE does not appear to significantly affect girls' performance test scores when they are expressed as z-score or relative to body mass. Boys born in the first and second quarters of the year had a significant physical advantage over their relatively younger peers. These findings have practical bearing if coaches use fitness tests for talent identification and team selection. Categorizing test performance based on rounded down values of whole-year age may disadvantage children born later in the selection year. These relatively younger children may be less to gain selection for teams or training programmes.