Habitual Physical Activity, Physical Fitness and Heart Rate Variability in Preadolescents

Abstract

The amount and type of physical activity (PA) appropriate in youth for optimal health is still being discussed. The purpose of this study on 12-year-old preadolescents is to evaluate the association of two PA patterns, corresponding to different exercise intensities, with some health-related indexes. PA was evaluated by triaxial accelerometry in 67 student subjects, who were successively classified according to 1) their usual participation or not in moderately intense (> 4 metabolic equivalents, METs) activities (either in daily life or in leisure activities) for at least 210 min a week (4 M (210)); and 2) the habitual practice or not of more intense activities (> 6 METs) for at least 60 min a week (6 M (60)). Health-related indexes consisted of cardiopulmonary (maximum oxygen uptake, V.O 2max), muscular (lower limb strength) fitness parameters and vagal-related indexes of heart rate (HR) variability (HRV), such as the HF/(LF+HF) ratio (where HF and LF stand for high and low frequency power). HR was recorded in the supine position after 15 min of quiet rest, and HRV indexes were calculated in 5-min segments. Energy expenditure due to PA was not significantly associated with any health-related index. Reaching 4 M (210) was associated with both higher estimated V.O 2max (p < 0.05) and higher muscular strength indexes (p < 0.05) but not with enhanced HRV indexes. Subjects who reached 6 M (60) had higher estimated V.O2max (p < 0.05) and higher HF/(LF+HF) (p < 0.05). Our results show that regular moderately intense activities are sufficient to influence physical fitness but suggest that more intense activities are necessary to observe more favorable HRV vagal-related indexes.

Association of physical activity with muscular strength and fat-free mass in adolescents: the HELENA study

“…Ara et al 18 showed in 114 prepubertal boys (9.4±1.5 years) that participation in at least 3 hours per week of extracurricular physical activities and sport competitions was associated with higher squat jump performance and lower fat mass levels compared with non-participants. In contrast, Buchheit et al 33 showed no association between PA measured by accelerometry and counter movement jump test in a sample of 67 preadolescents. Foo et al 34 Regardless of the evident gender differences, our results do not show any relationship between PA and fat free mass, and suggest that after controlling for the fat free mass, vigorous PA is the minimum physical stimulus able to enhance muscular strength.…”

Effects of eight weeks of physical training on physical performance and heart rate variability in children

“…The high physical activity level of adolescents provides health benefits, and it may also have a role in improving educational skills and well-being [12]. Previous studies have further shown that endurance training of prepubertal healthy children has a positive effect on aerobic potential, morphological parameters and functional cardiac parameters [3]. Being already physically active and the short training period in the test group could explain why their skeletal muscle mass did not change.…”

“…The acute effects of physical training and exercise on cardiac autonomic activity in young healthy participants [2,4,6] and in children with a pre-existing condition such as obesity [14] have been reported. In a meta-analysis of randomized controlled trials in healthy children, da Silva et al [5] found no effect of exercise training on HRV.…”

Effects of exercise on cardiac autonomic modulation in children: literature update

“…The wide possibilities for using HRV added to the ease of data acquisition enables its use for the identification of ANS-related phenomena in individuals of different ages and states of health, as well as making evaluation possible in individuals during rest or exercise (1,(12)(13)(14)(15)(16)(17).…”