Resistance training presents beneficial effects on bone development of adolescents engaged in swimming but not in impact sports: ABCD Growth Study

BACKGROUND

Sports practice during adolescence is important to enhance bone development, although it may provide different effects depending on the mechanical impact present in the sport. Besides, resistance training (RT) may also induce bone changes directly (via muscle contractions) and indirectly (via myokines). However, there have been no studies analyzing the longitudinal influence of engaging in sport with and without added mechanical load. Thus, this study aims to analyze the combined effects of sports participation and resistance training on areal bone mineral density (aBMD) accrual in adolescent athletes participating in swimming and impact sports for 12-months.

METHODS

This was a 12-month longitudinal study. The sample comprised 91 adolescents (21 females) aged 10 to 18 years, engaged in impact sports (basketball, tennis, track & field, baseball and gymnastics, n = 66) and non-impact sport (swimming, n = 25). The sample was divided according to resistance training participation: impact sports only (n = 45), impact sports + resistance training (n = 21), swimming-only (n = 17) and swimming + resistance training (n = 8). aBMD and soft tissues were measured using dual-energy X-ray absorptiometry. Generalized linear models analysis was used for the resistance training (RT) x type of sport interaction in predicting aBMD changes overtime, adjusting for maturation, sex and baseline aBMD.

RESULTS

After 12-months, all groups showed a significant increase in aBMD, except for the swimming groups (regardless of resistant training), which showed a significant loss in spine aBMD (-0.045 [-0.085 to -0.004] g/cm2 in swimming-only and - 0.047 [-0.073 to -0.021] g/cm2 in swimming + RT). In comparisons between groups, only swimming + RT group, compared with swimming-only group presented higher upper limbs aBMD (0.096 g/cm2 [0.074 to 0.118] in swimming + RT vs. 0.046 [0.032 to 0.060] g/cm2 in swimming only; p < 0.05) and whole body less head (WBLH) aBMD (0.039 [0.024 to 0.054] g/cm2 in swimming + RT vs. 0.017 [0.007 to 0.027] g/cm2 swimming-only; p < 0.05).

CONCLUSION

Despite the significant gain in aBMD in all groups and body sites after 12-months, except for the spine site of swimmers, the results indicate that participation in RT seems to improve aBMD accrual in swimmers at the upper limbs and WBLH.

Cross-sectional and longitudinal associations between the 24-hour movement behaviours, including muscle and bone strengthening activity, with bone and lean mass from childhood to adolescence

BACKGROUND

This study aimed to assess whether moderate-to-vigorous physical activity (MVPA), sport and exercise as a proxy measure of muscle and bone strengthening activity, sedentary behaviour, and sleep were associated with total-body-less-head (TBLH) bone mineral content (BMC) and TBLH lean mass cross-sectionally and longitudinally from age 6 to 9 years and age 9 to 11 years to age 15 to 17 years.

METHODS

We used longitudinal data from a population sample of Finnish children from the Physical Activity and Nutrition in Children study (age 6 to 9 years: n = 478, 229 females; age 9 to 11 years: n = 384, 197 females; age 15 to 17 years: n = 222, 103 females). Linear regression analysed the cross-sectional and longitudinal associations between accelerometer-assessed MVPA, sedentary time and sleep, and questionnaire-assessed sport and exercise participation and screen time with dual-energy X-ray absorptiometry-assessed TBLH BMC and lean mass.

RESULTS

In females, MVPA at age 6 to 9 years was positively associated with TBLH BMC at age 15 to 17 years (β = 0.008, p = 0.010). Sport and exercise at age 9 to 11 years was positively associated with TBLH BMC (β = 0.020, p = 0.002) and lean mass (β = 0.343, p = 0.040) at age 15 to 17 years. MVPA at age 9 to 11 years was positively associated with TBLH lean mass (β = 0.272, p = 0.004) at age 15 to 17 years. In males, sleep at age 6 to 9 years was positively associated with TBLH lean mass (β = 0.382, p = 0.003) at age 15 to 17 years. Sport and exercise at age 9 to 11 years was positively associated with TBLH BMC (β = 0.027, p = 0.012) and lean mass (β = 0.721, p < 0.001) at age 15 to 17 years.

CONCLUSIONS

Promoting engagement in the 24-hour movement behaviours in childhood, particularly sport and exercise to strengthen muscle and bone, is important in supporting bone and lean mass development in adolescence.

TRIAL REGISTRATION

NCT01803776; first trial registration date: 04/03/2013.

The effect of the Mid-Day Meal programme on the longitudinal physical growth from childhood to adolescence in India

The study aims to examine the effect of the world's largest school-feeding programme, the Mid-Day Meal (MDM) programme, on the changes in the underweight prevalence among school-children in India. Data from the Indian Human Development Survey (IHDS) Rounds 1 (2004-05) and 2 (2011-12) were utilized. The sample included individual-level information of children aged 6 to 9 years in IHDS-1 who then turned 13 to 16 years in IHDS-2. The sample was categorised into four groups based on their MDM consumption history (Group 1: no MDM support in IHDS-1 and IHDS-2, Group 2: MDM support in IHDS-1, Group 3: MDM support in IHDS-2, Group 4: persistent MDM support in IHDS-1 and IHDS-2). The dependent variable was underweight status as defined by the World Health Organisation Child Growth Standards Body Mass Index for age (BMI Z-score) < -2 SD of the median. Bivariate analysis was used to examine the prevalence of underweight and establish associations between underweight status and socio-demographic characteristics. Logistic regression was performed to assess the strength of the association of socio-demographic characteristics and MDM consumption patterns with underweight across poor and non-poor asset groups. The findings suggest that early and persistent MDM support among respondents reduced the likelihood of low BMI Z-scores compared to those without MDM support. Respondents from the poor asset group who received MDM support in at least one of the two survey rounds had higher odds of being underweight in comparison with those who did not receive MDM support at all. Girls and adolescents residing in the Eastern region of India were less likely to be underweight. The study shows that the MDM programme was effective in reducing the rate of underweight among school children. However, continuous programme upscaling with a special focus on children from poor households will significantly benefit India's school-aged children.

Determinants of bone parameters in young paediatric cancer survivors: the iBoneFIT project

BACKGROUND

Bone health is remarkably affected by endocrine side effects due to paediatric cancer treatments and the disease itself. We aimed to provide novel insights into the contribution of independent predictors of bone health in young paediatric cancer survivors.

METHODS

This cross-sectional multicentre study was carried out within the iBoneFIT framework in which 116 young paediatric cancer survivors (12.1 ± 3.3 years old; 43% female) were recruited. The independent predictors were sex, years from peak height velocity (PHV), time from treatment completion, radiotherapy exposure, region-specific lean and fat mass, musculoskeletal fitness, moderate-vigorous physical activity and past bone-specific physical activity.

RESULTS

Region-specific lean mass was the strongest significant predictor of most areal bone mineral density (aBMD), all hip geometry parameters and Trabecular Bone Score (β = 0.400-0.775, p ≤ 0.05). Years from PHV was positively associated with total body less head, legs and arms aBMD, and time from treatment completion was also positively associated with total hip and femoral neck aBMD parameters and narrow neck cross-sectional area (β = 0.327-0.398, p ≤ 0.05; β = 0.135-0.221, p ≤ 0.05), respectively.

CONCLUSION

Region-specific lean mass was consistently the most important positive determinant of all bone parameters, except for total hip aBMD, all Hip Structural Analysis parameters and Trabecular Bone Score.

IMPACT

The findings of this study indicate that region-specific lean mass is consistently the most important positive determinant of bone health in young paediatric cancer survivors. Randomised clinical trials focused on improving bone parameters of this population should target at region-specific lean mass due to the site-specific adaptations of the skeleton to external loading following paediatric cancer treatment. After paediatric cancer diagnosis, years from peak height velocity (somatic maturity) is critical for bone development.

Citizen Science to improve healthy and active living among adolescents in four European countries: a protocol of the cluster randomised controlled trial of the Science Engagement to Empower aDolescentS (SEEDS) project

INTRODUCTION

Improving healthy lifestyles of adolescents is challenging. Citizen Science is a way to engage them in the design and delivery of interventions, and may also increase their interest in science, technology, engineering and mathematics (STEM). The Science Engagement to Empower aDolescentS (SEEDS) project aims to use an equity-lens, and engage and empower boys and girls from deprived areas by designing and cocreating interventions to promote healthy lifestyles, and to seed interest in STEM.

METHODS AND ANALYSIS

SEEDS is a cluster randomised controlled trial in four countries (Greece, the Netherlands, Spain and the UK). Each country will recruit six to eight high schools from lower socioeconomic neighbourhoods. Adolescents aged 13-15 years are the target population. High schools will be randomised into intervention or control group. Each country will select 15 adolescents from intervention schools called ambassadors, who will be involved throughout the project.In each country, focus groups with ambassadors and stakeholders will focus on physical activity, snacking behaviour and STEM. The input from focus groups will be used to shape Makeathon events, cocreation events where adolescents and stakeholders will develop the interventions. The resultant intervention will be implemented in the intervention schools during 6 months. In total, we aim to recruit 720 adolescents who will complete questionnaires related to healthy lifestyles and STEM outcomes at baseline (November 2021) and after the 6 months (June 2022).

ETHICS AND DISSEMINATION

The four countries obtained approval from their corresponding Ethics Committees (Greece: Bioethics Committee of Harokopio University; the Netherlands: The Medical Research Ethics Committee of the Erasmus Medical Center; Spain: The Drug Research Ethics Committee of the Pere Virgili Health Research Institute; UK: Sport and Health Sciences Ethics Committee of the University of Exeter). Informed consent will be collected from adolescents and their parents in line with General Data Protection Regulation legislation. The findings will be disseminated by conference presentations, publications in scientific peer-reviewed journals and during (local) stakeholders and public events. Lessons learnt and the main results will also be used to provide policy recommendations.

TRIAL REGISTRATION NUMBER

NCT05002049.

Systematic review and meta-analysis: Associations of vitamin D with pulmonary function in children and young people with cystic fibrosis

BACKGROUND

Increasing evidence suggests that vitamin D is associated with pulmonary health, which may benefit children and young people diagnosed with Cystic Fibrosis (cypCF). Therefore, the aim of this systematic review was to evaluate primary research to establish associations between 25OHD and pulmonary health in cypCF.

METHODS

Electronic databases were searched with keywords related to CF, vitamin D, children/young people and pulmonary function. Included studies were cypCF (aged ≤21 years) treated in a paediatric setting. The primary outcome was lung function [forced expiratory volume in 1 s (FEV₁% predicted)] and secondary outcomes were rate of pulmonary exacerbations, 25OHD status and growth. Evidence was appraised for risk of bias using the CASP tool, and quality using the EPHPP tool. A Meta-analysis was performed.

RESULTS

Twenty-one studies were included with mixed quality ratings and heterogeneity of reported outcomes. The Meta-analysis including 5 studies showed a significantly higher FEV₁% predicted in the 25OHD sufficiency compared to the deficiency group [FEV₁% predicted mean difference (95% CI) was 7.71 (1.69-13.74) %; p = 0.01]. The mean ± SD FEV₁% predicted for the sufficient (≥75 nmol/L) vs. deficient (<50 nmol/L) group was 94.7 ± 31.9% vs. 86.9 ± 13.2%; I² = 0%; χ² = 0.5; df = 4). Five studies (5/21) found significantly higher rate of pulmonary exacerbations in those who were 25OHD deficient when compared to the sufficient group and negative associations between 25OHD and FEV% predicted. The effects of vitamin D supplementation dosages on 25OHD status (10/21) varied across studies and no study (12/21) showed associations between 25OHD concentration and growth.

CONCLUSION

This systematic review suggests that 25OHD concentration is positively associated with lung function and a concentration of >75 nmol/L is associated with reduced frequency of pulmonary exacerbations, which may slow lung function decline in cypCF. Future randomised clinical trials and mechanistic studies are warranted.

Physical activity volume and intensity distribution in relation to bone, lean and fat mass in children

Considering physical activity (PA) volume and intensity may provide novel insights into the relationships of PA with bone, lean, and fat mass. This study aimed to assess the associations of PA volume, PA intensity distribution, including moderate-to-vigorous PA (MVPA) with total-body-less-head bone mineral content (BMC), lean, and fat mass in children. A population sample of 290 Finnish children (158 females) aged 9-11 years from the Physical Activity and Nutrition in Children (PANIC) Study was studied. PA, including MVPA, was assessed with a combined heart rate and movement sensor, and the uniaxial acceleration was used to calculate average-acceleration (a proxy metric for PA volume) and intensity-gradient (reflective of PA intensity distribution). Linear regression analyzed the associations of PA volume, PA intensity and MVPA with BMC, lean mass, and fat mass assessed by dual-energy X-ray absorptiometry. PA volume was positively associated with BMC in females (unstandardised regression coefficient [ß] = 0.26) and males (ß = 0.47), and positively associated with lean (ß = 7.33) and negatively associated with fat mass in males (ß = -20.62). PA intensity was negatively associated with BMC in males (ß = -0.13). MVPA was positively associated with lean mass in females and males (ß = 0.007 to 0.012), and negatively associated with fat mass in females and males (ß = -0.030 to -0.029). PA volume may be important for improving BMC in females and males, and increasing lean and reducing fat mass in males, whereas MVPA may be important for favorable lean and fat outcomes in both sexes.

The Influence of Accelerometer Epoch Length on Associations of Physical Activity Intensity and Volume with Bone Outcomes

Two accelerometer metrics (intensity-gradient and average-acceleration) can be used to determine the relative contributions of physical activity (PA) volume and intensity for health, but it is unknown whether epoch length influences the associations detected. This is important when considering bone health, as bone is particularly responsive to high intensity PA, which may be underestimated by longer epochs. This study aimed to assess the associations between average-acceleration, a proxy measure of PA volume, and intensity-gradient, reflective of PA intensity distribution, from PA data from 1-s to 60-s epochs at age 17 to 23 years with bone outcomes at age 23 years. This is a secondary analysis of 220 participants (124 females) from the Iowa Bone Development Study, a longitudinal study of bone health from childhood to early adulthood. Accelerometer-assessed PA data, captured at age 17 to 23 years, were summarised over 1-s, 5-s, 15-s, 30-s, and 60-s epochs, to generate average-acceleration and intensity-gradient from each epoch length, averaged across ages. Regression analysed associations between mutually adjusted average-acceleration and intensity-gradient with dual-energy X-ray absorptiometry assessed total-body-less-head (TBLH) bone mineral content (BMC), spine areal bone mineral density (aBMD), hip aBMD, and femoral neck cross-sectional area and section modulus at age 23 years. Intensity-gradient was positively associated with TBLH BMC in females, with spine aBMD in males, and with hip aBMD and geometry in both sexes, when a 1 to 5-s epoch was used. Average-acceleration was positively associated with TBLH BMC, spine aBMD and hip aBMD in males, generally when the adjustment for intensity-gradient was from > 1-s epochs. Intensity and volume were important for bone outcomes in both sexes and males, respectively. A 1 to 5-s epoch length was most appropriate to assess the mutually adjusted associations of intensity-gradient and average-acceleration with bone outcomes in young adults.

School-based high-intensity interval training programs in children and adolescents: A systematic review and meta-analysis

PURPOSE

1) To investigate the effectiveness of school-based high-intensity interval training (HIIT) interventions in promoting health outcomes of children and adolescents compared with either a control group or other exercise modality; and 2) to explore the intervention characteristics and process outcomes of published school-based HIIT interventions.

METHODS

We searched Medline, Embase, CINAHL, SPORTDiscus, and Web of Science from inception until 31 March 2021. Studies were eligible if 1) participants aged 5-17 years old; 2) a HIIT intervention within a school setting ≥ 2 weeks duration; 3) a control or comparative exercise group; 4) health-related, cognitive, physical activity, nutrition, or program evaluation outcomes; and 5) original research published in English. We conducted meta-analyses between HIIT and control groups for all outcomes with ≥ 4 studies and meta-regressions for all outcomes with ≥ 10 studies. We narratively synthesised results between HIIT and comparative exercise groups.

RESULTS

Fifty-four papers met eligibility criteria, encompassing 42 unique studies (35 randomised controlled trials; 36 with a high risk of bias). Meta-analyses indicated significant improvements in waist circumference (mean difference (MD) = -2.5cm), body fat percentage (MD = -1.7%), body mass index (standardised mean difference (SMD) = -1.0), cardiorespiratory fitness (SMD = +1.0), resting heart rate (MD = -5bpm), homeostatic model assessment-insulin resistance (MD = -0.7), and low-density lipoprotein cholesterol (SMD = -0.9) for HIIT compared to the control group. Our narrative synthesis indicated mixed findings between HIIT and other comparative exercise groups.

CONCLUSION

School-based HIIT is effective for improving several health outcomes. Future research should address the paucity of information on physical activity and nutrition outcomes and focus on the integration and long-term effectiveness of HIIT interventions within school settings.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42018117567.

The Mediating Role of Endocrine Factors in the Positive Relationship Between Fat Mass and Bone Mineral Content in Children Aged 9-11 Years: The Physical Activity and Nutrition in Children Study

INTRODUCTION

We aimed to investigate whether the relationship between fat mass and bone mineral content (BMC) is mediated by insulin, leptin, adiponectin, dehydroepiandrosterone sulphate, testosterone and estradiol in children aged 9-11 years.

MATERIALS AND METHODS

We utilised cross-sectional data from the Physical Activity and Nutrition in Children study (n = 230 to 396; 112 to 203 girls). Fat mass and BMC were assessed with dual-energy X-ray absorptiometry. Endocrine factors were assessed from fasted blood samples. We applied the novel 4-way decomposition method to analyse associations between fat mass, endocrine factors, and BMC.

RESULTS

Fat mass was positively associated with BMC in girls (ß = 0.007 to 0.015, 95% confidence interval (CI) 0.005 to 0.020) and boys (ß = 0.009 to 0.015, 95% CI 0.005 to 0.019). The relationship between fat mass and BMC was mediated by free leptin index in girls (ß = -0.025, 95% CI -0.039 to -0.010) and boys (ß = -0.014, 95% CI -0.027 to -0.001). The relationship between fat mass and BMC was partially explained by mediated interaction between fat mass and free leptin index in boys (ß = -0.009, 95% CI -0.013 to -0.004) and by interaction between fat mass and adiponectin in girls (ß = -0.003, 95% CI -0.006 to -0.000).

CONCLUSION

At greater levels of adiponectin and free leptin index, the fat mass and BMC relationship becomes less positive in girls and boys respectively. The positive association between fat mass with BMC was largely not explained by the endocrine factors we assessed.

CLINICAL TRIAL REGISTRATION

[https://clinicaltrials.gov/ct2/show/NCT01803776], identifier NCT01803776.

The independent and interactive associations of physical activity intensity and vitamin D status with bone mineral density in prepubertal children: the PANIC Study

It is unclear how physical activity intensity and vitamin D status are related to bone health in prepubertal children. We found positive associations between vitamin D status and moderate-to-vigorous physical activity with bone in boys and girls. This highlights the importance of lifestyle factors for skeletal health prepuberty.

INTRODUCTION

The sex-specific independent and interactive associations of physical activity (PA) intensity and serum 25-hydroxyvitamin D (25(OH)D) levels with areal bone mineral density (aBMD) were investigated in prepubertal children.

METHODS

The participants were 366 prepubertal Finnish children (190 boys, 176 girls) aged 6-8 years. Linear regression analysed the associations of sedentary time (ST), light PA (LPA), moderate PA (MPA), moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) measured by accelerometery, and serum 25(OH)D with total body less head (TBLH) and lower-limb aBMD, measured by dual-energy X-ray absorptiometry.

RESULTS

There was no interaction between PA intensity or serum 25(OH)D and sex with aBMD. MPA and MVPA were positively associated with TBLH and lower-limb aBMD (β = 0.11, 95% CI 0.02-0.20, p = 0.01). Serum 25(OH)D was positively associated with TBLH and lower-limb aBMD (β = 0.09, 95% CI 0.01-0.18, p = 0.03). There were no interactions between PA intensity and serum 25(OH)D with aBMD.

CONCLUSION

Vitamin D status, MPA and MVPA levels in active prepubertal children were positively associated with aBMD. The influence of MVPA is due to the MPA component, though our findings regarding the role of VPA should be interpreted with caution, as shorter accelerometer epochs are needed to more accurately assess VPA. This study adds evidence to the promotion of MPA and behaviours to encourage optimal vitamin D status in supporting skeletal health in childhood, though these need not be used in conjunction to be beneficial, and a sex-specific approach is not necessary in prepubertal children.

TRIAL REGISTRATION NUMBER

NCT01803776 . Date of registration: 4/03/2013.

Categorizing 10 Sports According to Bone and Soft Tissue Profiles in Adolescents

PURPOSE

Considering the different loading and training characteristics of the sports practiced during growth, it is important to specify and categorize the bone and soft tissue adaptations in adolescent athletes. This study aimed to categorize 10 different loading sports and a nonsport group and identify the differences in bone density and soft tissues.

METHODS

The sample included 625 adolescents (10 to 17 yr of age) of 10 sports (soccer, basketball, volleyball, track and field, judo, karate, kung fu, gymnastics, baseball, and swimming) and a nonsport group. Dual-energy x-ray absorptiometry assessed areal bone mineral density (aBMD), bone mineral apparent density (BMAD), and soft tissues (lean soft tissue and fat mass). The results were adjusted for sex, peak height velocity status, lean soft tissue, fat mass, and weekly training volume.

RESULTS

The comparisons among groups showed that soccer had the highest whole-body aBMD (mean ± SEM: 1.082 ± 0.007 g·cm) and lower limb aBMD (1.302 ± 0.010 g·cm). Gymnastics presented the highest upper limb aBMD (0.868 ± 0.012 g·cm) and whole-body BMAD (0.094 ± 0.001 g·cm). Swimming presented the lowest aBMD values in all skeletal sites (except at the upper limbs) and whole-body BMAD. The soft tissue comparisons showed that soccer players had the highest lean soft tissue (43.8 ± 0.7 kg). The lowest fat mass was found in gymnasts (8.04 ± 1.0 kg).

CONCLUSION

The present study investigated and categorized for the first time 10 different sports according to bone density and soft tissue profiles. Soccer and gymnastics sport groups were found to have the highest bone density in most body segments, and both sports were among the groups with the lowest fat mass.

The effect of an online exercise programme on bone health in paediatric cancer survivors (iBoneFIT): study protocol of a multi-centre randomized controlled trial

BACKGROUND

New approaches on paediatric cancer treatment aim to maintain long-term health. As a result of radiotherapy, chemotherapy or surgery, paediatric cancer survivors tend to suffer from any chronic health condition. Endocrine dysfunction represents one of the most common issues and affects bone health. Exercise is key for bone mass accrual during growth, specifically plyometric jump training. The iBoneFIT study will investigate the effect of a 9-month online exercise programme on bone health in paediatric cancer survivors. This study will also examine the effect of the intervention on body composition, physical fitness, physical activity, calcium intake, vitamin D, blood samples quality of life and mental health.

METHODS

A minimum of 116 participants aged 6 to 18 years will be randomized into an intervention (n = 58) or control group (n = 58). The intervention group will receive an online exercise programme and diet counselling on calcium and vitamin D. In addition, five behaviour change techniques and a gamification design will be implemented in order to increase the interest of this non-game programme. The control group will only receive diet counselling. Participants will be assessed on 3 occasions: 1) at baseline; 2) after the 9 months of the intervention; 3) 4 months following the intervention. The primary outcome will be determined by dual energy X-ray absorptiometry (DXA) and the hip structural analysis, trabecular bone score and 3D-DXA softwares. Secondary outcomes will include anthropometry, body composition, physical fitness, physical activity, calcium and vitamin D intake, blood samples, quality of life and mental health.

DISCUSSION

Whether a simple, feasible and short in duration exercise programme can improve bone health has not been examined in paediatric cancer survivors. This article describes the design, rationale and methods of a study intended to test the effect of a rigorous online exercise programme on bone health in paediatric cancer survivors. If successful, the iBoneFIT study will contribute to decrease chronic health conditions in this population and will have a positive impact in the society.

TRIAL REGISTRATION

Prospectively registered in isrctn.com: isrctn61195625 . Registered 2 April 2020.

Impact of sports participation on incidence of bone traumatic fractures and health-care costs among adolescents: ABCD - Growth Study

Objective: To analyze the risk of bone traumatic fractures according to the engagement in sports, as well as to identify the potential impact of sports participation and traumatic fractures on health-care costs among adolescents. Methods: This is a longitudinal 12-month study of 285 adolescents of both sexes in Brazil. We assessed the occurrence of traumatic fractures and health-care services (hospitalizations, medicine use, medical consultations, and exams) by phone contact every month for 12 months. Adolescents were divided into four groups according to sport characteristics: non-sport (n = 104), non-impact sport (swimming [n = 34]), martial arts (n = 49 [judo, karate, kung-Fu]) and impact sports (n = 98 [track-and-field, basketball, gymnastics, tennis, and baseball]). Results: The incidence of new fractures was 2.1%. The overall costs accounted during the 12-month follow-up were U$ 3,259.66. Swimmers (US$ 13.86) had higher health-care costs than non-sport (US$ 1.82), martial arts (US$ 2.23), and impact sports (US$ 2.32). Conclusion: swimming seems to be related to higher health-care costs among adolescents.

Effects of post exercise protein supplementation on markers of bone turnover in adolescent swimmers

BACKGROUND

This study examined the effects of whey protein supplementation, compared with an isocaloric carbohydrate beverage and water, consumed immediately following an intense swimming trial on bone turnover in adolescent swimmers.

METHODS

Fifty-eight (31 female, 27 male) swimmers (14.1 ± 0.4 years) were stratified into three groups matched for age, sex and body mass. The protein and carbohydrate groups consumed two isocaloric post-exercise beverages each containing 0.3 g^.kg^- 1 of whey protein (with ~ 6 mg of calcium) or maltodextrin while the control group consumed water. Participants provided a morning, fasted, resting blood sample, then performed an intense swimming trial consisting of a maximal 200 m swim followed by a high intensity interval swimming protocol (5x100m, 5x50m and 5x25m; 1:1 work-to-rest ratio). Following swimming, they consumed their first respective post-exercise beverage, and 2 h later, they performed a second maximal swim immediately followed by the second beverage. Approximately 3 h after the second beverage, two post-consumption blood samples were collected at 8 h and 24 h from baseline. Procollagen type 1 intact N-terminal propeptide (PINP) and carboxy-terminal collagen crosslinks (CTXI) were measured in serum. The multiples of medians of PINP and CTXI were also used to calculate bone turnover rate and balance.

RESULTS

No significant changes were observed in PINP. CTXI increased (+ 11%) at 8 h in all groups, but then significantly decreased (- 22%) at 24 h in the protein group only. The protein group also had a significantly higher calculated rate of bone turnover at 8 h and 24 h compared to baseline, which was not observed in the other groups.

CONCLUSIONS

These results shed light on the potential importance of protein consumed shortly after intense swimming in promoting positive bone turnover responses up to 24 h following exercise in adolescent athletes.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov PRS; NCT04114045. Registered 1 October 2019 - Retrospectively registered.

Analysis of Bone Impairment by 3D DXA Hip Measures in Patients With Primary Hyperparathyroidism: A Pilot Study

CONTEXT

Primary hyperparathyroidism (PHPT) has been related to bone loss. Dual-energy x-ray absorptiometry (DXA) cannot distinguish between trabecular and cortical bone compartments but the recently developed three-dimensional (3D)-DXA software might overcome this issue.

OBJECTIVE

To examine the differences in DXA-derived areal bone mineral density (aBMD) and 3D-DXA parameters at the hip site between patients with PHPT and a healthy control group.

DESIGN

Cross-sectional pilot study.

SETTING

Hospital.

PATIENTS

80 adults (59.5 ± 9.1 yrs), 40 with PHPT and 40 age- and sex-matched healthy controls.

MEASURES

aBMD (g/cm2) of the femoral neck, trochanter, shaft, and total hip was assessed using DXA. Cortical surface (sBMD, mg/cm2), cortical volumetric BMD (vBMD, mg/cm3), trabecular vBMD (mg/cm3), integral vBMD (mg/cm3) and cortical thickness (mm) was assessed using 3D-DXA software.

RESULTS

Mean-adjusted values showed lower aBMD (7.5%-12.2%, effect size: 0.51-1.01) in the PHPT group compared with the control group (all P < 0.05). 3D-DXA revealed bone impairment (3.7%-8.5%, effect size: 0.47-0.65) in patients with PHPT, mainly in cortical parameters (all P < 0.05). However, differences in trabecular vBMD were not statistically significant (P = 0.055). The 3D mapping showed lower cortical sBMD, cortical vBMD, and cortical thickness at the trochanter and diaphysis in the PHPT group (P < 0.05) compared with the control group. In both groups, the presence of osteopenia or osteoporosis is related to lower cortical bone.

CONCLUSIONS

aBMD and cortical 3D parameters are impaired in patients with PHPT versus healthy controls. The vBMD of the trabecular compartment seems to be affected, although to a lesser extent.

Bone Health in Children and Youth with Cystic Fibrosis: A Systematic Review and Meta-Analysis of Matched Cohort Studies

OBJECTIVE

To assess the evidence regarding the differences in areal bone mineral density (aBMD) between children and adolescents with cystic fibrosis (CF) compared with their healthy peers, based on data from longitudinal studies.

STUDY DESIGN

We searched MEDLINE, SPORTDiscus, the Cochrane Library, PEDro (Physiotherapy Evidence Database), and Embase databases. Observational studies addressing the change of aBMD in children with CF and healthy children and adolescents were eligible. The DerSimonian and Laird method was used to compute pooled estimates of effect sizes (ES) and 95% CIs for the change of whole body (WB), lumbar spine (LS), and femoral neck (FN) aBMD.

RESULTS

Six studies with participants with CF and 26 studies with healthy participants were included in the systematic review and meta-analysis. For the analysis in children with CF, the pooled ES for the change of WB aBMD was 0.29 (95% CI -0.15 to 0.74), for the change of LS aBMD was 0.13 (95% CI -0.16 to 0.41), and for the change of FN aBMD was 0.09 (95% CI -0.39 to 0.57). For the analysis in healthy children, the pooled ES for the change of WB aBMD was 0.37 (95% CI 0.26-0.49), for the change of LS aBMD was 0.13 (95% CI -0.16 to 0.41), and for the change of FN aBMD was 0.52 (95% CI 0.19-0.85).

CONCLUSIONS

aBMD development might not differ between children and adolescents with CF receiving medical care compared with their healthy peers. Further longitudinal studies in a CF population during growth and development are required to confirm our findings.

A 9-Month Jumping Intervention to Improve Bone Geometry in Adolescent Male Athletes

PURPOSE

Sports have different effects on bone development and effective interventions to improve bone health of adolescent athletes are needed. The purpose of the study was to investigate the effect of a 9-month jumping intervention on bone geometry and metabolism in adolescent male athletes.

METHODS

Ninety-three adolescent (14.1 yr old) male swimmers (SWI), footballers (FOO), and cyclists (CYC) were randomized to intervention and sport (INT-SWI = 19, INT-FOO = 15, and INT-CYC = 14) or sport only (CON-SWI = 18, CON-FOO = 15, and CON-CYC = 12) groups. Cross-sectional area, cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck were assessed using hip structural analysis and trabecular texture of the lumbar spine using trabecular bone score. Bone mineral content (BMC) at femoral neck and lumbar spine was assessed using dual-energy x-ray absorptiometry. Serum N-terminal propeptide of procollagen type I, isomer of the carboxy-terminal telopeptide of type 1 collagen, total serum calcium, and 25-hydroxyvitamin D were analyzed.

RESULTS

INT-CYC acquired significantly higher lumbar spine BMC (4.6%) and femoral neck BMC (9.8%) than CON-CYC. INT-CYC acquired significantly higher cross-sectional area (11.0%), CSMI (10.1%), and trabecular bone score (4.4%) than CON-CYC. INT-SWI acquired significantly higher femoral neck BMC (6.0%) and CSMI (10.9%) than CON-SWI. There were no significant differences between INT-FOO and CON-FOO in any bone outcomes. N-terminal propeptide of procollagen type I significantly decreased in CON-SWI, INT-FOO, CON-FOO, and CON-CYC. Carboxy-terminal telopeptide of type 1 collagen significantly decreased in CON-SWI and CON-CYC. The 25-hydroxyvitamin D significantly increased in INT-CYC, CON-CYC, INT-FOO, and CON-FOO.

CONCLUSIONS

A 9-month jumping intervention improved bone outcomes in adolescent swimmers and cyclists, but not in footballers. This intervention might be used by sports clubs to improve bone health of adolescent athletes.

The association between childhood fractures and adolescence bone outcomes: a population-based study, the Tromsø Study, Fit Futures

Childhood fracture may predict persistent skeletal fragility, but it may also reflect high physical activity which is beneficial to bone development. We observe a difference in the relationship between previous fracture and bone outcome across physical activity level and sex. Further elaboration on this variation is needed.

PURPOSE

Childhood fracture may be an early marker of skeletal fragility, or increased levels of physical activity (PA), which are beneficial for bone mineral accrual. This study investigated the association between a previous history of childhood fracture and adolescent bone mineral outcomes by various PA levels.

METHODS

We recruited 469 girls and 492 boys aged 15-18 years to this study. We assessed PA levels by questionnaire and measured areal bone mineral density (aBMD) and bone mineral content (BMC) using dual-energy X-ray absorptiometry (DXA) at arm, femoral neck (FN), total hip (TH), and total body (TB) and calculated bone mineral apparent density (BMAD, g/cm³). Fractures from birth to time of DXA measurements were retrospectively recorded. We analyzed differences among participants with and without fractures using independent sample t test. Multiple linear regression was used to examine the association between fractures and aBMD and BMC measurements according to adolescent PA.

RESULTS

Girls with and without a previous history of fracture had similar BMC, aBMD, and BMAD at all sites. In multiple regression analyses stratified by physical activity intensity (PAi), there was a significant negative association between fracture and aBMD-TH and BMC-FN yet only in girls reporting low PAi. There was a significant negative association between forearm fractures, BMAD-FN, and BMAD-arm among vigorously active boys.

CONCLUSION

Our findings indicate a negative association between childhood fractures and aBMD/BMC in adolescent girls reporting low PAi. In boys, such an association appears only in vigorously active participants with a history of forearm fractures.

Longitudinal determinants of 12-month changes on bone health in adolescent male athletes

We identified the determinants of 12-month changes of areal bone mineral density (aBMD), hip geometry and trabecular bone score (TBS) in adolescent male athletes. Changes in region-specific lean mass and the type of sport are the most consistent determinants in this population.

PURPOSE

This study aims to identify the determinants of 12-month changes of areal bone mineral density (aBMD), hip geometry and trabecular bone score (TBS) in adolescent male athletes.

METHODS

The sample was 104 adolescent males aged 12-14 years at baseline that were followed over 12 months: 39 swimmers, 37 footballers (or soccer players) and 28 cyclists. Dual-energy X-ray absorptiometry measured aBMD at the whole body, lumbar spine and dual hip. Hip geometry estimates at the femoral neck were measured using hip structural analysis. Lumbar spine texture was measured by TBS.

RESULTS

Multivariate regression models significantly explained 38-60% of the variance in the aBMD changes, 36-62% in the hip geometry estimates changes and 45% in the TBS changes. Δregion-specific lean mass was the most consistent predictor of changes in aBMD outcomes (β = 0.591 to 0.696), followed by cycling participation (β = - 0.233 to - 0.262), swimming participation (β = - 0.315 to - 0.336) and ΔMVPA (β = 0.165). Cycling participation was the most consistent predictor of changes in hip geometry estimates (β = - 0.174 to - 0.268), followed by Δregion-specific lean mass (β = 0.587) and Δcardiorespiratory fitness (β = 0.253). Finally, cycling and swimming participation (β = - 0.347 to - 0.453), Δregion-specific lean mass (β = 0.848) and Δstature (β = 0.720) were predictors of change in TBS.

CONCLUSIONS

Changes in region-specific lean mass and the type of sport are the most consistent determinants of 12-month changes in aBMD, hip geometry estimates and TBS in adolescent male athletes.

TRIAL REGISTRATION

ISRCTN17982776.

The effect of a high-impact jumping intervention on bone mass, bone stiffness and fitness parameters in adolescent athletes

This study demonstrates that a 9-month jumping intervention can improve bone mass gains and physical fitness performance in adolescent males participating in non-osteogenic sports, such as swimming and cycling.

PURPOSE

To examine the effect of a jumping intervention on bone mass, bone stiffness and fitness parameters in adolescents involved in different sports.

METHODS

Ninety-three adolescent male swimmers (SWI), footballers (FOO) and cyclists (CYC) were randomised to intervention (INT) and sport (INT-SWI = 19, INT-FOO = 15, INT-CYC = 14) or sport only (CON-SWI = 18, CON-FOO = 15, CON-CYC = 12) groups. The 9-month jumping intervention consisted of 3 levels (12 weeks each) of 20 repetitions per set of counter movement jumps (CMJ) using adjustable weight vests (level 1 = 20 CMJ jumps/set, 0 kg, 3 sets/day, 3 times/week; level 2 = 20 CMJ jumps/set, 2 kg, 4 sets/day, 3 times/week; level 3 = 20 CMJ jumps/set, 5 kg, 4 sets/day, 4 times/week). Total body bone mineral content (BMC) at total body less head (TBLH) was measured using dual-energy X-ray absorptiometry and bone stiffness using quantitative ultrasound. Fitness was assessed using the 20-m shuttle run (20mSRT), CMJ and standing long jump (SLJ) tests.

RESULTS

INT-SWI had significantly higher increase in BMC legs and bone stiffness compared to CON-SWI (4.2-12.7%). INT-CYC had significantly higher increase in BMC at TBLH and legs and bone stiffness compared to CON-CYC (5.0-12.3%). There were no significant differences between INT-FOO and CON-FOO in any bone outcomes (0.9-3.9%). The increase in CMJ performance was significantly higher in INT-SWI (3.1 cm) and INT-CYC (3.2 cm) compared to CON-SWI and CON-CYC groups, respectively.

CONCLUSIONS

A 9-month jumping intervention can improve bone mass, bone stiffness and muscular fitness in adolescent males participating in non-osteogenic sports, such as swimming and cycling.

CLINICAL TRIAL REGISTRATION

ISRCTN17982776.

The influence of birth weight and length on bone mineral density and content in adolescence: The Tromsø Study, Fit Futures

The influence of birth weight and length on bone mineral parameters in adolescence is unclear. We found a positive association between birth size and bone mineral content, attenuated by lifestyle factors. This highlights the impact of environmental stimuli and lifestyle during growth.

PURPOSE

The influence of birth weight and length on bone mineral density and content later in life is unclear, especially in adolescence. This study evaluated the impact of birth weight and length on bone mineral density and content among adolescents.

METHODS

We included 961 participants from the population-based Fit Futures study (2010-2011). Dual-energy X-ray absorptiometry (DXA) was used to measure bone mineral density (BMD) and bone mineral content (BMC) at femoral neck (FN), total hip (TH) and total body (TB). BMD and BMC measures were linked with birth weight and length ascertained from the Medical Birth Registry of Norway. Linear regression models were used to investigate the influence of birth parameters on BMD and BMC.

RESULTS

Birth weight was positively associated with BMD-TB and BMC at all sites among girls; standardized β coefficients [95% CI] were 0.11 [0.01, 0.20] for BMD-TB and 0.15 [0.06, 0.24], 0.18 [0.09, 0.28] and 0.29 [0.20, 0.38] for BMC-FN, TH and TB, respectively. In boys, birth weight was positively associated with BMC at all sites with estimates of 0.10 [0.01, 0.19], 0.12 [0.03, 0.21] and 0.15 [0.07, 0.24] for FN, TH and TB, respectively. Corresponding analyses using birth length as exposure gave significantly positive associations with BMC at all sites in both sexes. The significant positive association between birth weight and BMC-TB in girls, and birth length and BMC-TB in boys remained after multivariable adjustment.

CONCLUSIONS

We found a positive association between birth size and BMC in adolescence. However, this association was attenuated after adjustment for weight, height and physical activity during adolescence.

Longitudinal Adaptations of Bone Mass, Geometry, and Metabolism in Adolescent Male Athletes: The PRO-BONE Study

Adolescence is a crucial period for bone development, and exercise can enhance bone acquisition during this period of life. However, it is not known how the different loading sports practiced can affect bone acquisition in adolescent male athletes. Therefore, the purpose of the present study was to determine the 1-year longitudinal bone acquisition among adolescent males involved in osteogenic (football) and non-osteogenic (swimming and cycling) sports and to compare with active controls. A total of 116 adolescent males aged 12 to 14 years at baseline were followed for 1 year: 37 swimmers, 37 footballers, 28 cyclists, and 14 active controls. Bone mineral content (BMC) was assessed using dual-energy X-ray absorptiometry (DXA); cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck was assessed using hip structural analysis (HSA); and bone texture of the lumbar spine was assessed using trabecular bone score (TBS). Serum N-terminal propeptide of procollagen type I (PINP), isomer of the Carboxi-terminal telopeptide of type 1 collagen (CTX-I), total serum calcium, and 25 hydroxyvitamin D [25(OH)D] were analyzed. Footballers had significantly higher adjusted BMC at the lumbar spine (7.0%) and femoral neck (5.0%) compared with cyclists, and significantly greater BMC at the lumbar spine (6.9%) compared with swimmers. Footballers presented significantly greater TBS (4.3%) compared with swimmers, and greater CSMI (10.2%), CSA (7.1%), Z (8.9%) and TBS (4.2%) compared with cyclists. No differences were noted between cyclists and swimmers, both groups had similar bone acquisition compared with controls. PINP was significantly higher in footballers and controls compared with cyclists and swimmers (3.3% to 6.0%), and 25(OH)D was significantly higher in footballers and cyclists compared with swimmers and controls (9.9% to 13.1%). These findings suggest that bone acquisition is higher in adolescent male footballers compared with swimmers and cyclists at the femoral neck and lumbar spine sites of the skeleton. © 2017 American Society for Bone and Mineral Research.

Lean mass explains the association between muscular fitness and bone outcomes in 13-year-old boys

AIM

This study investigated the associations between fitness indices and bone outcomes in young males.

METHODS

Data were collected between autumn and winter 2014-2015 on 121 males with a mean age of 13.1 ± 0.1 years: 41 swimmers, 37 footballers, 29 cyclists and 14 nonathletes. Participants were recruited from athletic clubs and schools across South West England. Lean mass, areal bone mineral density and hip structural estimates were measured using dual-energy X-ray absorptiometry. The relationships between bone outcomes and the vertical jump, standing long jump and the 20-m shuttle run test were analysed using three regression models: model 1 was adjusted by age and stature, model 2 added vigorous physical activity and model 3 then added lean mass.

RESULTS

The boys' performance in the vertical jump and standing long jump was positively associated with the majority of bone outcomes in models 1 and 2, but most of these disappeared in model 3. The 20-m shuttle run test was positively associated with most bone outcomes in all three models. Lean mass played a key role in the association between muscular fitness and bone outcomes.

CONCLUSION

Vigorous physical activity did not explain the associations between fitness and bone outcomes, but lean mass did.

The effect of 12-month participation in osteogenic and non-osteogenic sports on bone development in adolescent male athletes. The PRO-BONE study

OBJECTIVES

Research investigating the longitudinal effects of the most popular sports on bone development in adolescent males is scarce. The aim is to investigate the effect of 12-month participation in osteogenic and non-osteogenic sports on bone development.

DESIGN

A 12-month study was conducted in adolescent males involved in football, swimming and cycling and compared with an active control group.

METHODS

116 adolescent males (13.1±0.1years at baseline): 37 footballers, 37 swimmers, 28 cyclists and 14 active controls were followed for 12 months. Bone mineral content (BMC) was measured by dual-energy X-ray absorptiometry, and bone stiffness was measured by quantitative ultrasound. Bone outcomes at 12 months were adjusted for baseline bone status, age, height, lean mass and moderate to vigorous physical activity.

RESULTS

Footballers had higher improvement in adjusted BMC at the total body, total hip, shaft, Ward's triangle, legs and bone stiffness compared to cyclists (6.3-8.0%). Footballers had significantly higher adjusted BMC at total body, shaft and legs compared to swimmers (5.4-5.6%). There was no significant difference between swimmers and cyclists for any bone outcomes. Swimming and cycling participation resulted in non-significant lower bone development at most sites of the skeleton compared to controls (-4.3 to -0.6%).

CONCLUSIONS

Football participation induces significantly greater improvements in BMC and bone stiffness over 12 months compared to cycling and swimming.

CLINICAL TRIAL REGISTRATION

ISRCTN17982776.

Body Composition, Nutritional Profile and Muscular Fitness Affect Bone Health in a Sample of Schoolchildren from Colombia: The Fuprecol Study

The objective of the present study is to investigate the relationships between body composition, nutritional profile, muscular fitness (MF) and bone health in a sample of children and adolescents from Colombia. Participants included 1118 children and adolescents (54.6% girls). Calcaneal broadband ultrasound attenuation (c-BUA) was obtained as a marker of bone health. Body composition (fat mass and lean mass) was assessed using bioelectrical impedance analysis. Furthermore height, weight, waist circumference and Tanner stage were measured and body mass index (BMI) was calculated. Standing long-jump (SLJ) and isometric handgrip dynamometry were used respectively as indicators of lower and upper body muscular fitness. A muscular index score was also computed by summing up the standardised values of both SLJ and handgrip strength. Dietary intake and degree of adherence to the Mediterranean diet were assessed by a 7-day recall questionnaire for food frequency and the Kidmed questionnaire. Poor bone health was considered using a z-score cut off of ≤-1.5 standard deviation. Once the results were adjusted for age and Tanner stage, the predisposing factors of having a c-BUA z-score ≤-1.5 standard deviation included being underweight or obese, having an unhealthy lean mass, having an unhealthy fat mass, SLJ performance, handgrip performance, and unhealthy muscular index score. In conclusion, body composition (fat mass and lean body mass) and MF both influenced bone health in a sample of children and adolescents from Colombia. Thus promoting strength adaptation and preservation in Colombian youth will help to improve bone health, an important protective factor against osteoporosis in later life.

Exercise-Induced Oxidative Stress Responses in the Pediatric Population

Adults demonstrate an upregulation of their pro- and anti-oxidant mechanisms in response to acute exercise while systematic exercise training enhances their antioxidant capacity, thereby leading to a reduced generation of free radicals both at rest and in response to exercise stress. However, less information exists regarding oxidative stress responses and the underlying mechanisms in the pediatric population. Evidence suggests that exercise-induced redox perturbations may be valuable in order to monitor exercise-induced inflammatory responses and as such training overload in children and adolescents as well as monitor optimal growth and development. The purpose of this review was to provide an update on oxidative stress responses to acute and chronic exercise in youth. It has been documented that acute exercise induces age-specific transient alterations in both oxidant and antioxidant markers in children and adolescents. However, these responses seem to be affected by factors such as training phase, training load, fitness level, mode of exercise etc. In relation to chronic adaptation, the role of training on oxidative stress adaptation has not been adequately investigated. The two studies performed so far indicate that children and adolescents exhibit positive adaptations of their antioxidant system, as adults do. More studies are needed in order to shed light on oxidative stress and antioxidant responses, following acute exercise and training adaptations in youth. Available evidence suggests that small amounts of oxidative stress may be necessary for growth whereas the transition to adolescence from childhood may promote maturation of pro- and anti-oxidant mechanisms. Available evidence also suggests that obesity may negatively affect basal and exercise-related antioxidant responses in the peripubertal period during pre- and early-puberty.

Effect of a program of short bouts of exercise on bone health in adolescents involved in different sports: the PRO-BONE study protocol

BACKGROUND

Osteoporosis is a skeletal disease associated with high morbidity, mortality and increased economic costs. Early prevention during adolescence appears to be one of the most beneficial practices. Exercise is an effective approach for developing bone mass during puberty, but some sports may have a positive or negative impact on bone mass accrual. Plyometric jump training has been suggested as a type of exercise that can augment bone, but its effects on adolescent bone mass have not been rigorously assessed. The aims of the PRO-BONE study are to: 1) longitudinally assess bone health and its metabolism in adolescents engaged in osteogenic (football), non-osteogenic (cycling and swimming) sports and in a control group, and 2) examine the effect of a 9 month plyometric jump training programme on bone related outcomes in the sport groups.

METHODS/DESIGN

This study will recruit 105 males aged 12-14 years who have participated in sport specific training for at least 3 hours per week during the last 3 years in the following sports groups: football (n = 30), cycling (n = 30) and swimming (n = 30). An age-matched control group (n = 15) that does not engage in these sports more than 3 hours per week will also be recruited. Participants will be measured on 5 occasions: 1) at baseline; 2) after 12 months of sport specific training where each sport group will be randomly allocated into two sub-groups: intervention group (sport + plyometric jump training) and sport group (sport only); 3) exactly after the 9 months of intervention; 4) 6 months following the intervention; 5) 12 months following the intervention. Body composition (dual energy X-ray absorptiometry, air displacement plethysmography and bioelectrical impedance), bone stiffness index (ultrasounds), physical activity (accelerometers), diet (24 h recall questionnaire), pubertal maturation (Tanner stage), physical fitness (cardiorespiratory and muscular), bone turnover markers and vitamin D will be measured at each visit.

DISCUSSION

The PRO-BONE study is designed to investigate the impact of osteogenic and non-osteogenic sports on bone development in adolescent males during puberty, and how a plyometric jump training programme is associated with body composition parameters.