Physical Activity and Bone Mineral Accrual During Childhood and Adolescence

The epidemic that is osteoporosis has led to an increasing interest in bone mineral, and the factors that influence the levels of bone mineral, in recent years. While it is unrealistic to try and turn back the clock, a return to an increased level of physical activity may be an important consideration in terms of skeletal health. Peak bone mass is largely determined by heredity, but lifestyle and dietary patterns also influence the level of bone mineral accrued during the growing years. In this review, we summarize the evidence that vigorous weight-bearing physical activity and adequate calcium intake represent the best possibility for enhancing the attainment of an optimal level of bone mineral, within genetic limits.

Trends in physical activity participation and the impact of integrated campaigns among Australian adults, 1997-99

Objectives: To determine whether awareness of the moderate physical activity message and prevalence of participation changed among Australian adults between 1997 and 1999, and if changes differed across Australia. Methods: Data were compared on awareness of the moderate physical activity message and on physical activity participation from identical national physical activity surveys in 1997 and 1999. Results: In 1999, following integrated public health efforts, recognition of the Active Australia campaign was substantially higher in NSW/ACT (61.7%) than elsewhere (29.3%). Knowledge about benefits of moderate activity increased between 1997 and 1999, more so in States with public health campaigns. National participation in 'sufficient physical activity' declined between 1997 and 1999, from 63% to 57%, but the decline was smaller in NSW/ACT (4.4%) than in the other States (6.0%). Conclusions and implications: Declining trends in physical activity in Australia require increased public health investments, including strategic planning and public education, such as occurred in NSW (1997/98).

Tracking of physical activity from adolescence to adulthood: a population-based study

OBJECTIVE: To assess the association between regular physical activity in adolescence and leisure-time physical activity in adulthood, with emphasis on gender differences. METHODS: A population-based cross-sectional study was carried out in Pelotas, Southern Brazil, in 2003. A representative sample of households was selected in multiple stages and subjects aged 20-59 years were interviewed. Leisure-time physical activity was evaluated using the International Physical Activity Questionnaire. Data on adolescent physical activity were based on subjects' recall. RESULTS: Of 2,577 subjects interviewed, 27.5% were classified as adequately active, and 54.9% reported regular physical activity in adolescence. Subjects who engaged in regular physical activity during adolescence were more likely to be adequately active in adulthood (adjusted prevalence ratio 1.42; 95% CI: 1.23; 1.65). This effect was stronger in women (adjusted prevalence ratio: 1.51; 95% CI: 1.22; 1.86) than men (adjusted prevalence ratio: 1.35; 95% CI: 1.10; 1.67). CONCLUSIONS: Promoting physical activity in school age may be a successful intervention against the epidemic of adult inactivity. Although women were less likely to report regular physical activity in adolescence, the effect of this experience on adult behavior was stronger than in men.

Food consumption, physical activity and socio-economic status related to BMI, waist circumference and waist-to-height ratio in adolescents

Objective: To examine the association between obesity and food group intakes, physical activity and socio-economic status in adolescents. Design: A cross-sectional study was carried out in 2008. Cole’s cut-off points were used to categorize BMI. Abdominal obesity was defined by a waist circumference at or above the 90th percentile, as well as a waist-to-height ratio at or above 0?500. Diet was evaluated using an FFQ, and the food group consumption was categorized using sex-specific tertiles of each food group amount. Physical activity was assessed via a self-report questionnaire. Socio-economic status was assessed referring to parental education and employment status. Data were analysed separately for girls and boys and the associations among food consumption, physical activity, socio-economic status and BMI, waist circumference and waist-to-height ratio were evaluated using logistic regression analysis, adjusting the results for potential confounders. Setting: Public schools in the Azorean Archipelago, Portugal. Subjects: Adolescents (n 1209) aged 15–18 years. Results: After adjustment, in boys, higher intake of ready-to-eat cereals was a negative predictor while vegetables were a positive predictor of overweight/ obesity and abdominal obesity. Active boys had lower odds of abdominal obesity compared with inactive boys. Boys whose mother showed a low education level had higher odds of abdominal obesity compared with boys whose mother presented a high education level. Concerning girls, higher intake of sweets and pastries was a negative predictor of overweight/obesity and abdominal obesity. Girls in tertile 2 of milk intake had lower odds of abdominal obesity than those in tertile 1. Girls whose father had no relationship with employment displayed higher odds of abdominal obesity compared with girls whose father had high employment status. Conclusions: We have found that different measures of obesity have distinct associations with food group intakes, physical activity and socio-economic status.

Relationship of milk intake and physical activity to abdominal obesity among adolescents

Background: Diet and physical activity (PA) are recognized as important factors to prevent abdominal obesity (AO), which is strongly associated with chronic diseases. Some studies have reported an inverse association between milk consumption and AO. Objective: This study examined the association between milk intake, PA and AO in adolescents. Methods: A cross-sectional study was conducted with 1209 adolescents, aged 15–18 from the Azorean Archipelago, Portugal in 2008. AO was defined by a waist circumference at or above the 90th percentile. Adolescent food intake was measured using a semi-quantitative food frequency questionnaire, and milk intake was categorized as ‘low milk intake’ (<2 servings per day) or ‘high milk intake’ ( 2 servings per day). PA was assessed via a self-report questionnaire, and participants were divided into active (>10 points) and low-active groups ( 10 points) on the basis of their reported PA. They were then divided into four smaller groups, according to milk intake and PA: (i) low milk intake/low active; (ii) low milk intake/active; (iii) high milk intake/low active and (iv) high milk intake/active. The association between milk intake, PA and AO was evaluated using logistic regression analysis, and the results were adjusted for demographic, body mass index, pubertal stage and dietary confounders. Results: In this study, the majority of adolescents consumed semi-skimmed or skimmed milk (92.3%). The group of adolescents with high level of milk intake and active had a lower proportion of AO than did other groups (low milk intake/low active: 34.2%; low milk intake/active: 26.9%; high milk intake/low active: 25.7%; high milk intake/active: 21.9%, P = 0.008). After adjusting for confounders, low-active and active adolescents with high levels of milk intake were less likely to have AO, compared with low-active adolescents with low milk intake (high milk intake/low active, odds ratio [OR] = 0.412, 95% confidence intervals [CI]: 0.201– 0.845; high milk intake/active adolescents, OR = 0.445, 95% CI: 0.235–0.845).Conclusion: High milk intake seems to have a protective effect on AO, regardless of PA level

The importance of physical education classes in pre-school children

The purpose of this study was to analyse differences between total physical activity (TPA) and moderate-to-vigorous PA (MVPA) of pre-school children during daily school hours when they attended the physical education class (PED) and school days without PE class (NPED) and to assess the contribution of PE classes to TPA in school hours. The sample was composed of 193 pre-school healthy children (96 girls) aged from three to five years old and was conducted between February and December of 2008. Children wore accelerometers for at least four consecutive days during school hours. Data were analysed with specific software, age-specific counts-per-minute cut-off points and a 5 s epoch were used. Independent and general linear model repeated measures were used to assess differences between gender and differences between different days within each gender, respectively. Boys engaged more MVPA than girls (P < 0.05). During PED, pre-school children engaged significantly more in TPA and MVPA than during NPED (P < 0.05). PE class contributed, on average, 27.7% for the TPA and 32.8% of daily MVPA during PED in both gender. The results of this study suggest that structured PA such as a PE class increased the daily TPA and MVPA level of pre-school children.

Barcoding human physical activity to assess chronic pain conditions.

BACKGROUND: Modern theories define chronic pain as a multidimensional experience - the result of complex interplay between physiological and psychological factors with significant impact on patients' physical, emotional and social functioning. The development of reliable assessment tools capable of capturing the multidimensional impact of chronic pain has challenged the medical community for decades. A number of validated tools are currently used in clinical practice however they all rely on self-reporting and are therefore inherently subjective. In this study we show that a comprehensive analysis of physical activity (PA) under real life conditions may capture behavioral aspects that may reflect physical and emotional functioning.¦METHODOLOGY: PA was monitored during five consecutive days in 60 chronic pain patients and 15 pain-free healthy subjects. To analyze the various aspects of pain-related activity behaviors we defined the concept of PA 'barcoding'. The main idea was to combine different features of PA (type, intensity, duration) to define various PA states. The temporal sequence of different states was visualized as a 'barcode' which indicated that significant information about daily activity can be contained in the amount and variety of PA states, and in the temporal structure of sequence. This information was quantified using complementary measures such as structural complexity metrics (information and sample entropy, Lempel-Ziv complexity), time spent in PA states, and two composite scores, which integrate all measures. The reliability of these measures to characterize chronic pain conditions was assessed by comparing groups of subjects with clinically different pain intensity.¦CONCLUSION: The defined measures of PA showed good discriminative features. The results suggest that significant information about pain-related functional limitations is captured by the structural complexity of PA barcodes, which decreases when the intensity of pain increases. We conclude that a comprehensive analysis of daily-life PA can provide an objective appraisal of the intensity of pain.

30 minutes of physical activity a day is good for your health

This poster promotes the message that 30 minutes of moderate physical activity a day has substantial health benefits, and highlights the fact that you don’t have to do 30 minutes all in one go.

Physical activity and enhanced fitness to improve cognitive function in older people without known cognitive impairment

Physical activity is beneficial for healthy ageing. It may also help maintain good cognitive function in older age. Aerobic activity improves cardiovascular fitness, but it is not known whether this sort of fitness is necessary for improved cognitive function.��Eleven studies of aerobic physical activity programmes for healthy people over the age of 55 years have been included in this review. Eight of these 11 studies reported that aerobic exercise interventions resulted in increased fitness of the trained group and an improvement in at least one aspect of cognitive function. The largest effects were on cognitive speed, auditory and visual attention. However, the cognitive functions which improved were not the same in each study and the majority of comparisons yielded no significant results.��The data are insufficient to show that the improvements in cognitive function which can be attributed to physical exercise are due to improvements in cardiovascular fitness.

Physical activity and pregnancy

SUMMARY : The traditional medical advice for pregnant women has been to reduce their physical activity (PA) levels. The advice was based on concerns that exercise could affect pregnancy outcomes by increasing core body temperature, by increasing the risk of maternal musculoskeletal injury and by altering the transplacental transport of oxygen and nutrients to maternal skeletal muscle rather than to the developing foetus. In the meantime, several studies have provided new information on adaptation of the pregnant woman and her foetus to moderate PA. New investigations have shown no adverse maternal or neonatal outcomes, abnormal foetal growth, increase in early pregnancy loss, or late pregnancy complications. Moreover, enrolment in moderate PA has proven to result in marked health benefits including improved maternal cardiovascular function, reduction of excessive weight gain and fat retention, less complicated labour, improved foetal stress tolerance and neurobehavioral maturation. In view of the beneficial effects, current recommendations encourage healthy pregnant women to engage in 30 minutes of moderate PA on most, if not all, days of the week. This thesis work addressed several questions. Firstly, it examined whether compliance with the recommended levels of PA during pregnancy results in better preparedness for the sudden physical exertion of labour and delivery. Secondly, it measured PA during pregnancy as compared to postpartum. Lastly, it assessed the influence of pre-pregnancy body mass index on gestational resting metabolic rate. Data collection was conducted on healthy women living in Switzerland during the third trimester of pregnancy and postpartum. Total and activity energy expenditure was assessed through 24-hour heart rate and accelerations recordings, and cardiovascular fitness through an individual step-test. Information related to pregnancy, labour and delivery was collected from medical records. The results indicate that a minimum 30 min of moderate PA per day during pregnancy are associated with better cardiovascular fitness and lower risk of operative delivery with no negative effects on maternal and foetal conditions (study 1). Despite these benefits, a substantial proportion of pregnant women (39%) living in Switzerland do not meet the PA recommendations. The decrease in activity related energy expenditure during pregnancy compared to postpartum was measured to be around 100 kcal/day (~13%), whereas the total energy expenditure was found to increase by 300 kcal/day (study 2). Thus, the energy cost of late pregnancy in Switzerland corresponds to 200 kca/day. These findings are based on average values of the study group. It should be noted, however, that large variations in individual energy expenditure may occur depending on the pre-pregnancy body mass index (study 3). When adjusted to body weight, gestational resting metabolic rate is significantly lower among women of high pre-pregnancy body mass index compared to women of normal or low pre-pregnancy body mass index. This can be explained by the fact that resting metabolic rate is primarily a function of fat-free mass, and when expressed per kg body weight, it decreases as the percentage of body fat increases. If energy intake is not modified appropriately in order to match lower energy cost per kg body weight in overweight and obese women it will result in positive energy balance, thus contributing to the current trend towards increasing adiposity in affluent society. The results of these studies go beyond the current state of knowledge on PA and pregnancy (study 4) and provide valid evidence to guide clinical practice. In view of the current epidemic of sedentary behaviour and obesity related pathology, the findings contribute new and reliable information to public health policies regarding the effects of PA in pregnancy, an important period of life for both mother and infant.

Could a satellite-based navigation system (GPS) be used to assess the physical activity of individuals on earth?

OBJECTIVES: To test whether the Global Positioning System (GPS) could be potentially useful to assess the velocity of walking and running in humans. SUBJECT: A young man was equipped with a GPS receptor while walking running and cycling at various velocity on an athletic track. The speed of displacement assessed by GPS, was compared to that directly measured by chronometry (76 tests). RESULTS: In walking and running conditions (from 2-20 km/h) as well as cycling conditions (from 20-40 km/h), there was a significant relationship between the speed assessed by GPS and that actually measured (r = 0.99, P < 0.0001) with little bias in the prediction of velocity. The overall error of prediction (s.d. of difference) averaged +/-0.8 km/h. CONCLUSION: The GPS technique appears very promising for speed assessment although the relative accuracy at walking speed is still insufficient for research purposes. It may be improved by using differential GPS measurement.

Effects of recommended levels of physical activity on pregnancy outcomes.

OBJECTIVE: We sought to examine the relation between recommended levels of physical activity during pregnancy and pregnancy outcomes. STUDY DESIGN: We conducted an observational study with energy expenditure, aerobic fitness, and sleeping heart rate measured in 44 healthy women in late pregnancy. Medical records were examined for pregnancy outcome. RESULTS: Active women, who engaged in > or = 30 minutes of moderate physical activity per day, had significantly better fitness and lower sleeping heart rate compared to the inactive. Duration of second stage of labor was 88 and 146 minutes in the active vs inactive women, respectively (P = .05). Crude odds ratio of operative delivery in the inactive vs the active was 3.7 (95% confidence interval, 0.87-16.08). Birthweight, maternal weight gain, and parity adjusted odds ratio was 7.6 (95% confidence interval, 1.23-45.8). Neonatal condition and other obstetric outcomes were similar between groups. CONCLUSION: Active women have better aerobic fitness as compared to inactive women. The risk for operative delivery is lower in active women compared to inactive, when controlled for birthweight, maternal weight gain, and parity. Further studies with larger sample size are required to confirm the association between physical activity and pregnancy outcomes.

Physical activity modulates heat shock protein-72 expression and limits oxidative damage accumulation in a healthy elderly population aged 60 90 years

BACKGROUND: Reactive oxygen species production increases during aging, whereas protective mechanisms such as heat shock proteins (HSPs) or antioxidant capacity are depressed. Physical activity has been hypothesized to provide protection against oxidative damage during aging, but results remain controversial. This study aimed to investigate the effect of different levels of physical activity during aging on Hsp72 expression and systemic oxidative stress at rest and in response to maximal exercise. METHODS: Plasma antioxidant capacity (Trolox equivalent antioxidant capacity, TEAC), thiobarbituric acid-reactive species (TBARS), advanced oxidized proteins products (AOPP), and Hsp72 expression in leukocytes were measured before and after maximal exercise testing in 32 elderly persons (aged 73.2 years), who were assigned to two different groups depending on their level of physical activity during the past 12 months (OLow = moderate to low level; OHigh = higher level). RESULTS: The OHigh group showed higher aerobic fitness and TEAC (both representing 120% of OLow values) as well as lower oxidative damage (50% of OLow values) and Hsp72 expression. Exercise led to a lower increase in oxidative damage in the OHigh group. Aerobic fitness was positively correlated with TEAC and negatively with lipid peroxidation (TBARS). Hsp72 expression was negatively correlated with TEAC but positively correlated with TBARS levels. CONCLUSIONS: The key finding of this study is that, in people aged 60 to 90 years, long-term high level of physical activity preserved antioxidant capacity and limited oxidative damage accumulation. It also downregulated Hsp72 expression, an adaptation potentially resulting from lower levels of oxidative damage.