Asymptomatic Achilles tendon pathology is associated with a central fat distribution in men and a peripheral fat distribution in women: a cross sectional study of 298 individuals.

BACKGROUND: Adiposity is a modifiable factor that has been implicated in tendinopathy. As tendon pain reduces physical activity levels and can lead to weight gain, associations between tendon pathology and adiposity must be studied in individuals without tendon pain. Therefore, the purpose of this study was to determine whether fat distribution was associated with asymptomatic Achilles tendon pathology. METHODS: The Achilles tendons of 298 individuals were categorised as normal or pathological using diagnostic ultrasound. Fat distribution was determined using anthropometry (waist circumference, waist hip ratio [WHR]) and dual-energy x-ray absorptiometry. RESULTS: Asymptomatic Achilles tendon pathology was more evident in men (13%) than women (5%) (p = 0.007). Men with tendon pathology were older (50.9 +/- 10.4, 36.3 +/- 11.3, p < 0.001), had greater WHR (0.926 +/- 0.091, 0.875 +/- 0.065, p = 0.039), higher android/gynoid fat mass ratio (0.616 +/- 0.186, 0.519 +/- 0.142, p = 0.014) and higher upper-body/lower body fat mass ratio (2.346 +/- 0.630, 2.022 +/- 0.467, p = 0.013). Men older than 40 years with a waist circumference >83 cm had the greatest prevalence of tendon pathology (33%). Women with tendon pathology were older (47.4 +/- 10.0, 36.0 +/- 10.3, p = 0.008), had less total fat (17196 +/- 3173 g, 21626 +/- 7882 g, p = 0.009), trunk fat (7367 +/- 1662 g, 10087 +/- 4152 g, p = 0.003) and android fat (1117 +/- 324 g, 1616 +/- 811 g, p = 0.005). They had lower central/peripheral fat mass ratios (0.711 +/- 0.321 g, 0.922 +/- 0.194 g, p = 0.004) than women with normal tendons. Women with tendon pathology were more often menopausal (63%, 13%, p = 0.002). CONCLUSIONS: Men with Achilles tendon pathology were older and had a central fat distribution. Women with tendon pathology were older and had a peripheral fat distribution. An interaction between age and waist circumference was observed among men.

The lifestyle of our kids (LOOK) project: outline of methods.

This methods paper outlines the overall design of a community-based multidisciplinary longitudinal study with the intent to stimulate interest and communication from scientists and practitioners studying the role of physical activity in preventive medicine. In adults, lack of regular exercise is a major risk factor in the development of chronic degenerative diseases and is a major contributor to obesity, and now we have evidence that many of our children are not sufficiently active to prevent early symptoms of chronic disease. The lifestyle of our kids (LOOK) study investigates how early physical activity contributes to health and development, utilizing a longitudinal design and a cohort of eight hundred and thirty 7-8-year-old (grade 2) school children followed to age 11-12 years (grade 6), their average family income being very close to that of Australia. We will test two hypotheses, that (a) the quantity and quality of physical activity undertaken by primary school children will influence their psychological and physical health and development; (b) compared with existing practices in primary schools, a physical education program administered by visiting specialists will enhance health and development, and lead to a more positive perception of physical activity. To test the first hypothesis we will monitor all children longitudinally over the 4 years. To test the second we will involve an intervention group of 430 children who receive two 50min physical education classes every week from visiting specialists and a control group of 400 who continue with their usual primary school physical education with their class-room teachers. At the end of grades 2, 4, and 6 we will measure several areas of health and development including blood risk factors for chronic disease, cardiovascular structure and function, physical fitness, psychological characteristics and perceptions of physical activity, bone structure and strength, motor control, body composition, nutritional intake, influence of teachers and family, and academic performance.

Discordance of international adiposity classifications in Australian boys and girls - the LOOK study.

BACKGROUND: Various charts based on body mass index (BMI) and per cent body fat (%BF) are used to classify childhood body composition but outcomes may vary. AIM: The study investigated variation in incidences of childhood obesity as depicted by four classification charts. SUBJECTS AND METHODS: BMI and DXA-derived %BF were assessed in 741 children. Incidences of overweight and obesity were compared between two BMI charts and two bioelectrical impedance (BIA)-based %BF charts. RESULTS: The International Obesity Task Force (IOTF)-adopted BMI chart designated 21%, 6% (boys), and 26%, 9% (girls) as overweight and obese, respectively. Corresponding figures using the USA CDC BMI chart were 27%, 11% (boys) and 27%, 12% (girls). Using a USA-derived %BF chart incidences were 17%, 2% (boys) and 21%, 8% (girls) and using a UK-derived %BF chart 51%, 24% (boys) and 53%, 36% (girls). Sensitivity of BMI varied according to the %BF reference chart. CONCLUSIONS: In contrast to the BMI-based charts, there were considerable variations in depicted incidences of obesity between the %BF-based charts. These discordances were considered to result from previously reported variation within and between BIA and DXA %BF assessments underlying the charts. The present study highlights the need for valid, reliable, unchanging BIA and DXA procedures.

Exercise and calcium combined results in a greater osteogenic effect than either factor alone: a blinded randomized placebo-controlled trial in boys.

UNLABELLED: We examined the combined effects of exercise and calcium on BMC accrual in pre- and early-pubertal boys. Exercise and calcium together resulted in a 2% greater increase in femur BMC than either factor alone and a 3% greater increase in BMC at the tibia-fibula compared with the placebo group. Increasing dietary calcium seems to be important for optimizing the osteogenic effects of exercise. INTRODUCTION: Understanding the relationship between exercise and calcium during growth is important given that the greatest benefits derived from these factors are achieved during the first two decades of life. We conducted a blinded randomized-controlled exercise-calcium intervention in pre- and early-pubertal boys to test the following hypotheses. (1) At the loaded sites (femur and tibia-fibula), exercise and calcium will produce greater skeletal benefits than either exercise or calcium alone. (2) At nonloaded sites (humerus and radius-ulna), there will be an effect of calcium supplementation. MATERIALS AND METHODS: Eighty-eight pre- and early-pubertal boys were randomly assigned to one of four study groups: moderate impact exercise with or without calcium (Ca) (Ex+Ca and Ex+placebo, respectively) or low impact exercise with or without Ca (No-Ex+Ca and No-Ex+Placebo, respectively). The intervention involved 20 minutes of either moderate- or low-impact exercise performed three times a week and/or the addition of Ca-fortified foods using milk minerals (392+/-29 mg/day) or nonfortified foods over 8.5 months. Analysis of covariance was used to determine the main and combined effects of exercise and calcium on BMC after adjusting for baseline BMC. RESULTS: At baseline, no differences were reported between the groups for height, weight, BMC, or bone length. The increase in femur BMC in the Ex+Ca group was approximately 2% greater than the increase in the Ex+placebo, No-Ex+Ca, or No-Ex+Placebo groups (all p<0.03). At the tibia-fibula, the increase in BMC in the Ex+Ca group was approximately 3% greater than the No-Ex+placebo group (p<0.02) and 2% greater than the Ex+Placebo and the No-Ex+Ca groups (not significant). No effect of any group was detected at the humerus, ulna-radius, or lumbar spine for BMC, height, bone area, or volume. CONCLUSIONS: In this group of normally active boys with adequate calcium intakes, additional exercise and calcium supplementation resulted in a 2-3% greater increase in BMC than controls at the loaded sites. These findings strengthen the evidence base for public health campaigns to address both exercise and dietary changes in children for optimizing the attainment of peak BMC.

Growth of highly versus moderately trained competitive female artistic gymnasts.

PURPOSE: To investigate whether growth was adversely affected in 137 young competitive female artistic gymnasts involved in different training volumes. METHODS: This was a 2-yr prospective cohort study in which height, sitting height, leg length, weight, skinfolds, and pubertal status were measured in competitive advanced (20-27 h x wk(-1)) and intermediate (7.5-22 h x wk(-1)) training level female gymnasts every 6-12 months. Biological parameters of the adolescent growth curve were estimated using the Preece-Baines growth model. Growth rates were estimated for both groups from the mixed-longitudinal data. RESULTS: Estimated ages at peak height velocity (PHV) (13-13.5 yr) and mean PHV (6.2-6.4 cm x yr(-1)) for the advanced- and intermediate-level gymnasts suggest that these gymnasts were later maturing and experienced a blunting of the growth spurt relative to reference values for U.S. youth. Comparison of growth velocities by pubertal status revealed that height velocity was lower in the advanced- versus the intermediate-level peripubertal gymnasts, which was due to a significant reduction in sitting height velocity (2.3 vs 3.1 cm x yr(-1), P. < 0.05). No marked acceleration in height or sitting height velocity was detected in the advanced-level gymnasts from pre- to peripuberty. Inspection of individual growth rates revealed that over 35% of the pre- and peripubertal gymnasts experienced growth faltering (height velocity less than 4.5 cm x yr(-1)) during follow-up. CONCLUSION: Advanced-and intermediate-training level competitive female gymnasts tend to exhibit an adolescent growth spurt that is similar in timing and tempo to short, normal, slowly maturing girls, but the high frequency of growth faltering suggests that training may alter the tempo of growth and maturation in some, but not all, female gymnasts.

Near normalisation of lumbar spine bone density in young women with osteopenia recovered from adolescent onset anorexia nervosa: a longitudinal study.

To investigate the effect of the progression of adolescent onset anorexia nervosa (AN) on bone parameters we followed two cohorts (Disease cohort and recovered cohort) of adolescents for a total of 5.2 years. In the 'Disease' cohort (n = 18), lumbar spine bone density (BMD) was reduced by 0.6 SD after 0.8 years of disease and was reduced a further 1.0 SD after a total 2.5 years of disease (p < 0.001). At the third lumbar vertebra there was bone loss (-3.7%, p < 0.05) resulting in reduced volumetric BMD (-5.1%, p < 0.08). In the 'recovered' cohort, lumbar spine BMD was reduced by 1.9 SD after 1.7 years of disease, and increased by 1.5 SD after 2.7 years of recovery (p < 0.001). At the third lumbar vertebra there was an increase in bone mass (20.5%, p < 0.001) and bone volume (14.1%, p < 0.001), resulting in increased volumetric BMD (6.3%, p < 0.08). Normalisation of lumbar spine BMD may be achieved in patients with adolescent onset AN when the successful recovery of body weight is combined with the return of regular menses.

Regional specificity of exercise and calcium during skeletal growth in girls: a randomized controlled trial.

Combining exercise with calcium supplementation may produce additive or multiplicative effects at loaded sites; thus, we conducted a single blind, prospective, randomized controlled study in pre- and early-pubertal girls to test the following hypotheses. (1) At the loaded sites, exercise and calcium will produce greater benefits than exercise or calcium alone. (2) At non-loaded sites, exercise will have no benefit, whereas calcium with or without exercise will increase bone mass over that in exercise alone or no intervention. Sixty-six girls aged 8.8 +/- 0.1 years were randomly assigned to one of four study groups: moderate-impact exercise with or without calcium or low-impact exercise with or without calcium. All participants exercised for 20 minutes, three times a week and received Ca-fortified (434 +/- 19 mg/day) or non-fortified foods for 8.5 months. Analysis of covariance (ANCOVA) was used to determine interaction and main effects for exercise and calcium on bone mass after adjusting for baseline bone mineral content and growth in limb lengths. An exercise-calcium interaction was detected at the femur (7.1%, p < 0.05). In contrast, there was no exercise-calcium interaction detected at the tibia-fibula; however, there was a main effect of exercise: bone mineral content increased 3% more in the exercise than non-exercise groups (p < 0.05). Bone mineral content increased 2-4% more in the calcium-supplemented groups than the non-supplemented groups at the humerus (12.0% vs. 9.8%, respectively, p < 0.09) and radius-ulna (12.6% vs. 8.6%, respectively, p < 0.01). In conclusion, greater gains in bone mass at loaded sites may be achieved when short bouts of moderate exercise are combined with increased dietary calcium, the former conferring region-specific effects and the latter producing generalized effects.

Effects of repetitive loading on the growth-induced changes in bone mass and cortical bone geometry: a 12-month study in pre/peri- and postmenarcheal tennis players.

Pre- and early puberty may be the most opportune time to strengthen the female skeleton, but there are few longitudinal data to support this claim. Competitive female premenarcheal (pre/peri, n = 13) and postmenarcheal (post, n = 32) tennis players aged 10 to 17 years were followed over 12 months. The osteogenic response to loading was studied by comparing the playing and nonplaying humeri for dual-energy X-ray absorptiometry (DXA) bone mineral content (BMC) and magnetic resonance imaging (MRI) total bone area (ToA), medullary area (MedA), cortical area (CoA), and muscle area (MCSA) at the humerus. Over 12 months, growth-induced gains (nonplaying arm) in BMC, ToA, and CoA were greater in pre/peri (10% to 19%, p < .001) than in post (3% to 5%, p < .05 to .001) players. At baseline, BMC, ToA, CoA, and MCSA were 8% to 18% greater in the playing versus nonplaying arms in pre/peri and post players (all p < .001); MedA was smaller in the playing versus nonplaying arms in post only players (p < .05). When comparing the annual gains in the playing arm relative to changes in the nonplaying arm, the increases in ToA and CoA were greater in pre/peri than post players (all p < .05). The smaller the side-to-side differences in BMC and CoA at baseline, the larger the exercise benefits at 12 months (r = -0.39 to -0.48, p < .01). The exercise-induced change in MCSA was predictive of the exercise benefits in BMC in pre/peri players only (p < .05). In conclusion, both pre/peri- and postmenarcheal tennis players showed significant exercise-induced skeletal benefits within a year, with greater benefits in cortical bone geometry in pre/perimenarcheal girls.

The ultrasound appearance of the patellar tendon attachment to the tibia in young athletes is conditional on gender and pubertal stage.

This cross-sectional study investigated the imaging appearance of the patellar tendon attachment to the tibia in young male and female tennis players of different ages and pubertal status. Forty-four competitive young players, who had been playing tennis at least for 2 years, were recruited from a tennis school and local tennis clubs. All subjects had bilateral ultrasound imaging of the patellar tendon attachment to the tibia. Standard anthropometric measurements, pubertal status and injury history were recorded. Ultrasound appearance of the patellar tendon attachment was categorised into three stages: cartilage attachment, insertional cartilage and mature attachment. Cartilage attachment was more prevalent in boys (32%) and extended further into puberty (until Tanner stage 4) compared to girls (6% and Tanner stage 1). Tendons with Osgood-Schlatter Disease symptoms (n=3) did not have a cartilage attachment. Imaging appearance commonly seen in young active athletes, consistent with a clinical diagnosis of OSD, was more common in boys and in the pre- and peri-pubertal stages.

Effects of repetitive loading on bone mass and geometry in young male tennis players: a quantitative study using MRI.

Pre- and early puberty seem to be the most opportune times for exercise to improve bone strength in girls, but few studies have addressed this issue in boys. This study investigated the site-, surface-, and maturity-specific exercise-induced changes in bone mass and geometry in young boys. The osteogenic effects of loading were analyzed by comparing the playing and nonplaying humeri of 43 male pre-, peri-, and postpubertal competitive tennis players 10-19 yr of age. Total bone area, medullary area, and cortical area were determined at the mid (40-50%) and distal humerus (60-70%) of both arms using MRI. Humeral bone mass (BMC) was derived from a whole body DXA scan. In prepubertal boys, BMC was 17% greater in the playing compared with nonplaying arm (p < 0.001), which was accompanied by a 12-21% greater cortical area, because of greater periosteal expansion than medullary expansion at the midhumerus and periosteal expansion associated with medullary contraction at the distal humerus. Compared with prepuberty, the side-to-side differences in BMC (27%) and cortical area (20-33%) were greater in peripuberty (p < 0.01). No differences were found between peri- and postpuberty despite longer playing history in the postpubertal players. The osteogenic response to loading was greater in peri- compared with prepubertal boys, which is in contrast with our previous findings in girls and may be caused by differences in training history. This suggests that the window of opportunity to improve bone mass and size through exercise may be longer in boys than in girls.

Is adiposity an under-recognized risk factor for tendinopathy? A systematic review.

OBJECTIVE: Tendon injuries have been reported to occur more frequently in individuals with increased adiposity. Treatment also appears to have poorer outcomes among these individuals. Our objective was to examine the extent and consistency of associations between adiposity and tendinopathy. METHODS: A systematic review of observational studies was conducted. Eight electronic databases were searched (Allied and Complementary Medicine, Biological Abstracts, CINAHL, Current Contents, EMBase, Medline, SPORTDiscus, and Web of Science) and citation tracking was performed on included reports. Studies were included if they compared adiposity between subjects with and without tendon injury or examined adiposity as a predictor of conservative treatment success. RESULTS: Four longitudinal cohorts, 14 cross-sectional studies, 8 case-control studies, and 2 interventional studies (28 in total) met the inclusion criteria, providing a total of 19,949 individuals. Forty-two subpopulations were identified, 18 of which showed elevated adiposity to be associated with tendon injury (43%). Sensitivity analyses indicated a clustering of positive findings among studies that included clinical patients (81% positive) and among case-control studies (77% positive). CONCLUSION: Elevated adiposity is frequently associated with tendon injury. Published reports suggest that elevated adiposity is a risk factor for tendon injury, although this association appears to vary depending on aspects of study design and measurement. Adiposity is of particular interest in tendon research because, unlike a number of other reported risk factors for tendon injury, it is somewhat preventable and modifiable. Further research is required to determine if reducing adiposity will reduce the risk of tendon injury or improve the results of treatment.

Overweight children have a greater proportion of fat mass relative to muscle mass in the upper limbs than in the lower limbs: implications for bone strength at the distal forearm.

BACKGROUND: The influence of adiposity on upper-limb bone strength has rarely been studied in children, despite the high incidence of forearm fractures in this population. OBJECTIVE: The objective was to compare the influence of muscle and fat tissues on bone strength between the upper and lower limbs in prepubertal children. DESIGN: Bone mineral content, total bone cross-sectional area, cortical bone area (CoA), cortical thickness (CoTh) at the radius and tibia (4% and 66%, respectively), trabecular density (TrD), bone strength index (4% sites), cortical density (CoD), stress-strain index, and muscle and fat areas (66% sites) were measured by using peripheral quantitative computed tomography in 427 children (206 boys) aged 7-10 y. RESULTS: Overweight children (n = 93) had greater values for bone variables (0.3-1.3 SD; P < 0.0001) than did their normal-weight peers, except for CoD 66% and CoTh 4%. The between-group differences were 21-87% greater at the tibia than at the radius. After adjustment for muscle cross-sectional area, TrD 4%, bone mineral content, CoA, and CoTh 66% at the tibia remained greater in overweight children, whereas at the distal radius total bone cross-sectional area and CoTh were smaller in overweight children (P < 0.05). Overweight children had a greater fat-muscle ratio than did normal-weight children, particularly in the forearm (92 +/- 28% compared with 57 +/- 17%). Fat-muscle ratio correlated negatively with all bone variables, except for TrD and CoD, after adjustment for body weight (r = -0.17 to -0.54; P < 0.0001). CONCLUSIONS: Overweight children had stronger bones than did their normal-weight peers, largely because of greater muscle size. However, the overweight children had a high proportion of fat relative to muscle in the forearm, which is associated with reduced bone strength.

Changes in sedentary behavior among adolescent girls: a 2.5-year prospective cohort study.

PURPOSE: To describe longitudinal changes in leisure-time sedentary behavior among girls, during early to mid-adolescence. METHODS: A 2.5-year prospective cohort study, comprising 5 data collections, 6 months apart, between 2000 and 2002. Girls aged 12-15 years (n = 200) from 8 high schools located in Sydney, Australia, self-reported the usual time spent each week in a comprehensive range of sedentary behaviors. RESULTS: Retention rate for the study was 82%. Girls aged 12.8 years spent approximately 45% of their discretionary time in sedentary behavior, which increased to 63% at age 14.9 years. Watching TV, videos, and playing video games (small screen recreation; SSR) was the most popular sedentary pastime, accounting for 33% of time spent in sedentariness, followed by homework and reading (25%). Sedentary behavior increased 1.4 and 3.3 hours on week and weekend days, respectively. On weekdays, increased time was spent on hobbies (27 min/day) and on weekend days, increased time was spent sitting around talking with friends (60 min/day), computer use (37 min/day), and television viewing (34 min/day). CONCLUSIONS: Among girls, the transition between early and mid-adolescence was accompanied by a significant increase in leisure-time sedentary behavior. Interventions to reduce sedentariness among adolescent girls are best to focus on weekend behaviors. Studies seeking to examine the association between inactivity and the development of chronic health problems need to examine a diverse range of activities that comprehensively measure sedentariness. This information will provide a better understanding of inactivity patterns among adolescent girls.