Trends of Sedentary Time and Domain-Specific Sedentary Behavior in Spanish Schoolchildren

Purpose: To examine the temporal trends of accelerometer-based total daily sedentary time (ST) and self-reported domain-specific sedentary behavior (SB) on weekdays and weekends in Spanish children. Method: A total of 560 (50.53% girls) children (4th graders) in 2011/12 from 23 Spanish schools and 462 (48.70% girls) children (4th graders) in 2017/18 from 19 schools across Cadiz participated. Hip-worn accelerometers and questionnaires were used to assess total daily ST and self-reported time in SB modalities, respectively. Results: The objectively measured total daily ST tended to increase in boys on weekdays and weekends. Time spent watching television (TV) decreased during the week and weekend days, while time surfing on the internet increased on weekdays and weekends. Playing video-games increased in boys during the weekends. The trend to increase the time spent on educational activities with a computer during the weekdays and weekends was accompanied by a reduction of the same activities without using a computer. There was a trend to increase reading for fun, talking on the phone and total time in other SB, on weekdays and weekends in boys and girls. Conclusion(s): Spanish boys tended to increase objectively measured total daily ST. Moreover, SB modalities have changed in recent years in children, replacing TV viewing by computer use for both educational and non-educational purposes, as well as by the use of smartphones or other sedentary activities that does not imply the presence of a screen. These findings highlight the need to promote interventions to decrease total daily ST and reduce SB activities.

The Federated Practice of Soccer Influences Hamstring Flexibility in Healthy Adolescents: Role of Age and Weight Status

The aim of this study was to compare the hamstring flexibility between federated soccer and non-federated adolescents, and also to evaluate the effect of age and weight status on hamstring flexibility. The participants were 234 students (11–18 years old) divided into: (i) G1: non-federated (n = 127), and (ii) G2: federated in soccer (n = 107). The deep flexion of the trunk (DF) test and the sit and reach test (SRT) were performed. G2 showed higher values for the DF and SRT compared to G1 (p < 0.05). Both flexibility tests correlated positively (r = 0.4, p < 0.001). Body mass index (BMI) was negatively correlated with the DF test (r = −0.3, p < 0.001), but not with the SRT. Divided by BMI, the underweight and normal weight groups had higher scores in the DF test compared with the overweight and obese groups (p < 0.001). BMI was negatively correlated with hamstring flexibility. Federated soccer students present higher scores of hamstring flexibility.

Teachers' knowledge about type 1 diabetes in south of Spain public schools

AIMS

To evaluate the knowledge of teachers in educative public centres (pre-, primary, and secondary schools) about type 1 diabetes (T1D) in the Puerto Real University Hospital area (Cadiz, Spain).

METHODS

Descriptive observational study in which 756 teachers' answers on the Test of Diabetes Knowledge for Teachers (TDKT) were analysed. Teachers from 44 educative public centres in the Puerto Real University Hospital area (Cadiz, Spain) were selected by randomized sampling (mean age, 44.3 ± 8 years; 61.7% women).

RESULTS

Although 43.2% survey respondents recognised having had or currently having children or adolescent students with T1D, most demonstrated they did not have enough knowledge about T1D (mean score, 6.0 ± 4.3 points from a maximum of 16), and only 5.1% had sufficient knowledge (13-16 points) to be an effective support person to students with diabetes in school. However, the vast majority of survey respondents correctly answered questions about symptoms (74.2%) and hypoglycaemia treatment (85.9%). Univariate analysis of factors associated with teachers' knowledge about diabetes revealed that teachers with ≤ 15 years of teaching experience and physical education teachers had better knowledge than their co-workers.

CONCLUSIONS

It is necessary to improve teachers' knowledge about diabetes in our health area with the aim of improving the security of children and adolescent students with T1D in school centres.

Convergent validation of a questionnaire to assess the mode and frequency of commuting to and from school

AIMS

The purposes of this research were to study the convergent validity of the Mode and Frequency of Commuting To and From School Questionnaire using objectively assessed steps and time spent in different physical activity intensities and to compare the self-reported versus objective journey time in Spanish youths.

METHODS

Three hundred and eighty-nine Spanish youth aged 7-19 years were asked to complete the questionnaire and wore an accelerometer for five days. The objective commuting distance and time from home to school were estimated using Google Maps^TM.

RESULTS

There were significant differences between passive and walking participants on step numbers, sedentary time and physical activity levels (except for vigorous physical activity in children). For children, a mean difference of -4.03 minutes between objective measured and self-reported journey time was found (95% limits of agreement were 13.55 and -21.60 minutes). For adolescents, the mean difference was -1.39 minutes (95% limits of agreement were 15.23 and -18.02 minutes).

CONCLUSIONS

The findings indicated that the Mode of Commuting To and From School Questionnaire showed a convergent validity to assess this behaviour in Spanish youths. Self-reported journey time for walking is comparable to Google Maps^TM in adolescents but not in children.

Muscle strength is associated with lower diastolic blood pressure in schoolchildren

Cardiorespiratory fitness (CRF) provides protection against the elevated blood pressure in overweight youth. Less is known regarding any similar protective effect of muscular fitness. We investigated how handgrip strength, an easy to implement measure of muscular strength, interacted with CRF and BMI to determine blood pressure in youth. We measured systolic (SBP) and diastolic (DBP) blood pressure, handgrip strength (HG), CRF and body mass index (BMI) in n=7329 10-16year-olds (47% girls). We defined elevated blood pressure as >91st percentile and Good HG as >33rd percentile. Participants were classified as Fit or Unfit and as Normal or Overweight/Obese based on international standards. The prevalence of elevated SBP was 23%, and 44% of participants had elevated DBP. In unfit participants Good HG was associated with lower SBP (z=0.41 (95%CI: 0.20-0.61) and DBP (z=0.29 (95%CI: 0.12-0.47). In Overweight/Obese participants, DBP was z=0.24 (95%CI: 0.14-0.34) lower in the Good (versus Low) HG group. Overweight/Obese participants with Good HG also had a 32% lower risk of elevated DBP (OR: 0.68, 95%CI: 0.57-0.82). This association was attenuated but remained important after adjusting for BMI (20% risk reduction, OR: 0.80, 95%CI: 0.63-1.01). Muscular fitness appears to play some protective role against the risk of elevated blood pressure; particularly for the more prevalent measure: elevated DBP (44%). Effects may be restricted to Overweight / Obese or unfit youth, who have an increased risk of elevated BP and also may be less likely to engage in traditional cardiorespiratory fitness training. Research to determine the effects of muscular fitness training on blood pressure is warranted in these subgroups.

Physical fitness as a mediator between objectively measured physical activity and clustered metabolic syndrome in children and adolescents: The UP&DOWN study

BACKGROUND AND AIMS

The extent to which physical fitness (PF) attenuates or modifies the association between physical activity (PA) and clustered metabolic syndrome risk factors (CMetSRF) is controversial. We aimed: i) To examine the independent and combined association of objectively measured PA and PF with CMetSRF in children and adolescents; ii) To test the mediating effect of PF in the association of PA with CMetSRF.

METHODS AND RESULTS

A total of 226 children and 256 adolescents participated. Levels of PA (light, moderate, vigorous and moderate-to-vigorous [MVPA]) and PF were measured by accelerometry and ALPHA battery, respectively. Cardiorespiratory and muscular fitness values were combined in a global PF variable. A CMetSRF was computed by assessing the following variables: waist circumference, systolic blood pressure, high-density lipoprotein cholesterol, triglycerides and glucose. In children, the highest vigorous PA (β = -0.193; P = 0.003) and MVPA (β = -0.149; P = 0.025) were individually associated with lower CMetSRF, but these associations were not independent of global PF. In adolescents, the association of moderate (β = -0.123; P = 0.046) and MVPA (β = -0.147; P = 0.024) with CMetSRF was independent of PF. Among unfit adolescents, the higher time they spent in MVPA the lower CMetSRF levels were found (P = 0.032).

CONCLUSIONS

The results are suggestive of a full mediation of global PF in the association of MVPA and vigorous PA with CMetSRF in children. In adolescents, the association of higher moderate and MVPA with lower CMetSRF was independent of levels of PF, and mediation analyses suggest only a partial mediation of global PF in the association of MVPA with CMetSRF.

Objectively measured physical activity has a negative but weak association with academic performance in children and adolescents

AIM

There is an emerging body of evidence on the potential effects of regular physical activity on academic performance. The aim of this study was to add to the debate, by examining the association between objectively measured physical activity and academic performance in a relatively large sample of children and adolescents.

METHODS

The Spanish UP & DOWN study is a 3-year longitudinal study designed to assess the impact, overtime, of physical activity and sedentary behaviours on health indicators. This present analysis was conducted with 1778 children and adolescents aged 6-18 years. Physical activity was objectively measured by accelerometry. Academic performance was assessed using school grades.

RESULTS

Physical activity was inversely associated with all academic performance indicators after adjustment for potential confounders, including neonatal variables, fatness and fitness (all p < 0.05). This association became nonsignificant among quartiles of physical activity. There were only slight differences in academic performance between the lowest and the second quartile of physical activity, compared to the highest quartile, with very small effect size (d < 0.20).

CONCLUSION

Objectively measured physical activity may influence academic performance during both childhood and adolescence, but this association was negative and very weak. Longitudinal and intervention studies are necessary to further our understanding.