S. Berntsen

Validity of physical activity monitors in adults participating in free-living activities

Background For a given subject, time in moderate to very vigorous intensity physical activity (MVPA) varies substantially among physical activity monitors. Objective In the present study, the primary objective, whether time in MVPA recorded with SenseWear Pro2 Armband (Armband; BodyMedia, Pittsburgh, Pennsylvania, USA), ActiGraph (7164, LLC, Fort Walton Beach, Florida, USA), ikcal (Teltronic AG, Biberist, Switzerland) and ActiReg (PreMed AS, Oslo, Norway) is different compared with indirect calorimetry, was determined. The secondary objective, whether these activity monitors estimate energy expenditure differently compared with indirect calorimetry, was also determined. Material and methods The activity monitors and a portable oxygen analyser were worn by 14 men and 6 women for 120 min doing a variety of activities of different intensities. Resting metabolic rate was measured with indirect calorimetry. The cutoff points defining moderate, vigorous and very vigorous intensity were three, six and nine times resting metabolic rate. Results Time in MVPA was overestimated by 2.9% and 2.5% by Armband and ActiGraph, respectively, and was underestimated by 11.6% and 98.7% by ikcal and ActiReg, respectively. ActiReg (p = 0.004) and ActiGraph (p = 0.007) underestimated energy expenditure in MVPA, and all monitors underestimated total energy expenditure (by 5% to 21%). Conclusions Recorded time in MVPA and energy expenditure varies substantially among physical activity monitors. Thus, when comparing physical activity level among studies, it is essential to know the type of physical activity monitor being used.

Norwegian adolescents with asthma are physical active and fit

Background:u2002 Evidence regarding habitual physical activity levels and aerobic fitness of asthmatic compared to nonasthmatic children and adolescents is contradictory, and it is unclear if low physical activity levels can contribute to asthma development. The present study therefore aimed to determine whether adolescents with asthma have reduced physical activity levels and aerobic fitness, or increased energy intake and body fat compared to controls.

Lung function at 10 yr is not impaired by early childhood lower respiratory tract infections

The causal relationship between lower respiratory tract infections (LRIs) in early life and reduced lung function later in childhood is unsettled. Therefore, we assessed whether LRIs the first 2u2003yr of life influenced lung function development from birth to school age. In the prospective Oslo birth cohort, ‘the Environment and Childhood Asthma (ECA) study’ lung function was measured at birth in 802 infants by tidal flow volume loops and in 664 infants by passive respiratory mechanics and half yearly questionnaires, including LRI questions, were completed until 2u2003yr of age. The present study includes 607 children with information about LRIs the first 2u2003yr of life and successfully forced expiratory flow (FEF) volume measurements at the 10‐yr follow‐up assessment. At 10u2003yr of age, FEF at 50% of forced vital capacity (FEF50) (mean 95% confidence interval) was reduced in children with at least one bronchiolitis (85.0, 80.6–89.5, pu2003=u20030.020) or bronchitis (86.2, 82.6–89.8, pu2003=u20030.030) or ≥3 LRIs (83.4, 78.1–88.8, pu2003=u20030.017) when compared with no LRIs (90.6, 88.8–92.5) by 2u2003yr of life. The effects were significant in girls only when stratifying for gender. Among girls with later bronchiolitis compliance of the respiratory system (3.64, 3.17–4.10 vs. 4.18, 3.98–4.37, pu2003=u20030.031) and the ratio of time to peak tidal expiratory flow to total expiratory time (tPTEF/tE) measured at birth was significantly reduced (0. 26, 0.23–0.29 vs. 0.32, 0.30–0.33, pu2003=u20030.005) when compared with children with no LRIs. Change in lung function from birth (by tPTEF/tE) to 10u2003yr of age was not significantly associated with LRIs the first 2u2003yr of life, and LRIs by 2u2003yr of life were not significantly associated with lung function at 10u2003yr of age in regression analyses including lung function at birth and other possible predictors of lung function at 10u2003yr. In our study, LRIs during the first 2u2003yr of life did not impair lung function development from birth until 10u2003yr of age.

Obese children playing towards an active lifestyle

AIMnTo determine whether five months of guided active play in overweight or obese children and adolescents under multi-disciplinary management for weight reduction leads to increased physical activity levels in leisure time, as well as changes in aerobic fitness and body composition.nnnMETHODSnSixty overweight or obese children and adolescents were randomly assigned to an intervention or control group. All participants received dietary advice and were encouraged to increase physical activity level. The intervention group additionally participated in 60-minute guided active play/physical activity twice a week for 5 months. Physical activity was recorded; aerobic fitness and body composition were measured at inclusion and after cessation of intervention.nnnRESULTSnPhysical activity level during weekend days was significantly higher for the intervention group compared with the controls after 5 months intervention (p=0.04). The mean reduction in percentage of body fat was 1.8% (95%CI: 0.6, 3.1) in the intervention group (p=0.04) and not significant among the controls (0.9 [-0.9, 2.7]). There was no change in aerobic fitness.nnnCONCLUSIONnFive months of guided active play was associated with increased physical activity levels during weekend days and reduced body fat, although weakly, in overweight and obese children and adolescents participating in multi-disciplinary weight reduction programmes.

A comparison of estimated maximal oxygen uptake in 9 and 10 year old schoolchildren in Tanzania and Norway

Objective: To compare estimated maximal oxygen uptake (V˙O2max) in Tanzanian and Norwegian children, by using the same bicycle protocol in both samples. Methods: Maximal oxygen uptake was estimated from an indirect maximal watt cycle ergometer test in 156 rural boys and girls in Tanzania. Similarly aged urban Norwegian boys and girls (nu200a=u200a379) who underwent the same test were used for comparison. The Tanzanian children also participated in a 20 metre shuttle run test and a test of bicycle skill. The Tanzanian children were tested at altitude (∼1800 metres), while the Norwegian children were tested at sea level. Results: In the cycle ergometer test, estimated relative V˙O2max was similar in Tanzanian and Norwegian boys, while Tanzanian girls had 8% lower estimated V˙O2max compared with Norwegian girls (p<0.001). Only one third of the Tanzanian children were able to ride a conventional bicycle. Excluding subjects not able to ride a bicycle, there was no difference in estimated V˙O2max between Norwegian and Tanzanian children. The Tanzanian boys and girls reached significantly higher estimated V˙O2max in the shuttle run test compared with the cycle ergometer test (p<0.001). Conclusions: Tanzanian and Norwegian children attained similar relative V˙O2max in the cycle ergometer test. However, the comparison was hampered by differences in altitude and the poor cycle ergometer skills in the Tanzanian children, both of which probably underestimated their V˙O2max.

Asthma symptoms in rural living Tanzanian children; prevalence and the relation to aerobic fitness and body fat.

Objective:u2002 To determine the prevalence of asthma symptoms in children from a rural district in North‐Tanzania, and their relationship to aerobic fitness and body fat.

Asthma in medium altitude - exercise-induced bronchoconstriction in hypobaric environment in subjects with asthma

Background:u2002 Hypoxic gas inhalation has been reported to enhance airway responsiveness and results in bronchoconstriction in animal models and in humans with asthma. However, the data have so far been conflicting. The aim of the present study was to examine the effect of reduced barometric pressure on exercise‐induced bronchoconstriction (EIB) in subjects with asthma.

Physical Activity in Childhood Asthma: Friend or Foe?:

Physical activity has been considered as a double-edged sword for children with asthma. Children with asthma are recommended to participate in physical activities like their healthy nonasthmatic peers because regular physical activity positively affects psychological functioning, quality of life, morbidity, and aerobic fitness in children with asthma. However, uncontrolled asthma with ongoing exercise-induced bronchoconstriction may limit participation in sports, free play, and daily living. Observations also suggest that high-intensity exercise performed in cold air, seasonal allergens, pollutants, or respiratory virus infections may increase the risk for asthma in the highly active child. In contrast, a sedentary lifestyle has been highlighted as the explanation for the increased prevalence of asthma in the past decades. However, there is no consensus on whether a low level of physical activity increases the severity or risk of asthma. Use of asthma medications and good asthma control can make the conditions favorable for a physically active lifestyle and influence physical activity level and the level of aerobic fitness.