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  • Author: Niina Lintu x
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Niina Lintu, Kai Savonen, Anna Viitasalo, Tuomo Tompuri, Jussi Paananen, Mika P. Tarvainen and Timo Lakka

Background:

There are few studies on determinants of cardiorespiratory fitness (CRF) among girls and boys separately in population samples of children.

Methods:

We therefore investigated the determinants of CRF, assessed by maximal workload per height using allometric scaling, in a population sample of 162 girls and 177 boys aged 6 to 8 years. We used automated bootstrap feature selection and linear regression models.

Results:

The strongest determinants of CRF among girls were maximal heart rate (HR; standardized regression coefficient [β] = 0.31, P < .001), unsupervised physical activity (β = 0.29, P < .001), lean body mass (β = 0.23, P = .001), and errors in static balance test (β = –0.16, P = .02), accounting altogether for 25.7% of variation in CRF. In boys, unsupervised physical activity (β = 0.24, P < .001), resting HR (β = –0.25, P < .001), hand grip strength (β = 0.21, P = .001), errors in static balance test (β = –0.16, P = .01), organized football (β = 0.16, P = .01), and unsupervised trampoline jumping (β = 0.14, P = .04) were the strongest determinants of CRF, accounting altogether for 29.7% of variation in CRF.

Conclusions:

These findings suggest that unsupervised physical activity is sufficient in improving CRF in both sexes. Furthermore, larger muscle mass and better balance are associated with higher CRF that has to be taken into account when assessing CRF using maximal cycle ergometer exercise test among children.

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Eero A. Haapala, Juuso Väistö, Aapo Veijalainen, Niina Lintu, Petri Wiklund, Kate Westgate, Ulf Ekelund, Virpi Lindi, Soren Brage and Timo A. Lakka

Purpose:

To investigate the relationships of objectively measured physical activity (PA) and sedentary time (ST) to arterial stiffness in prepubertal children.

Method:

Altogether 136 children (57 boys, 79 girls) aged 6–8-years participated in the study. Stiffness index (SI) was assessed by pulse contour analysis based on photoplethysmography. ST, light PA, moderate PA, and vigorous PA were assessed using combined acceleration and heart rate monitoring. We investigated the associations of ST (<1.5METs) and time spent in intensity level of PA above 2–7METs in min/d with SI using linear regression analysis. We studied the optimal duration and intensity of PA to identify children being in the highest quarter of SI using Receiver Operating Characteristics curves.

Results:

Moderate PA, vigorous PA, and cumulative time spent in PA above 3 (β=–0.279, p = .002), 4 (β =–0.341, P<0.001), 5 (β =–0.349, P<0.001), 6 (β =–0.312, P<0.001), and 7 (β =–0.254, p = .005) METs were inversely associated with SI after adjustment for age, sex, and monitor wear time. The cutoffs for identifying children being in the highest quarter of SI <68 min/d for PA exceeding 5 METs and <26 min/d for PA exceeding 6 METs.

Conclusion:

Lower levels of PA exceeding 3–6 METs were related to higher arterial stiffness in children.

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Andrew O. Agbaje, Eero A. Haapala, Niina Lintu, Anna Viitasalo, Juuso Väistö, Sohaib Khan, Aapo Veijalainen, Tuomo Tompuri, Tomi Laitinen and Timo A. Lakka

Purpose: To investigate the associations of directly measured peak oxygen uptake (V˙O2peak) and body fat percentage (BF%) with arterial stiffness and arterial dilatation capacity in children. Methods: Findings are based on 329 children (177 boys and 152 girls) aged 8–11 years. V˙O2peak was assessed by a maximal cardiopulmonary exercise test on a cycle ergometer and scaled by lean body mass (LM). BF% and LM were measured by bioelectrical impedance. Stiffness index (measure of arterial stiffness) and change in reflection index (ΔRI, measure of arterial dilatation capacity) were assessed by pulse contour analysis. Data were analyzed by linear regression models. Results: V˙O2peak/LM was positively associated with ΔRI in boys adjusted for age and BF% (β = 0.169, P = .03). Further adjustments for systolic blood pressure, heart rate, and the study group had no effect on this association, but additional adjustment for clinical puberty attenuated it (β = 0.171, P = .07). BF% was inversely related to ΔRI in boys adjusted for age and V˙O2peak/LM (β = −0.171, P = .03). V˙O2peak or BF% was not associated with ΔRI in girls or with stiffness index in either boys or girls. Conclusion: Increasing cardiorespiratory fitness and decreasing adiposity may improve arterial health in childhood, especially among boys.