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.

Upper and lower limb bone mass accrual in adolescent footballers across a short period of training and competition.

OBJECTIVES: To analyze bone mineral content (BMC) and area bone mineral density (aBMD) accrual in adolescent male footballers who started their first football season. METHODS: 17 athletes (14.8 ± 0.4 years) were monitored across 15 weeks of football training. Participants were evaluated for somatic maturation (HPHV), BMC, and aBMD at three time points: before (M1) and after (M2) a preparatory phase, and at the end of the competitive phase (M3). BMC and aBMD were measured using DXA scans. Participants were divided into groups according to maturation status (circa-PHV and post-PHV), and the amount of accumulated training load (median split). RESULTS: A significant effect (12.1 g/week, standard error (SE) = 2.6 g/week) was observed for lower limbs BMC across the three time points. There were no significant effects of time for upper limbs BMC. There was a significant effect of time for total body aBMD (0.007, SE = 0.003 g/cm2/week) across the three time points. Adolescents at post-PHV had a significant 245.6 g (SE = 56.1 g) higher BMC compared to adolescents at circa-PHV. No significant effects were observed for the accumulated training load. CONCLUSION: Systematic football training, even during the growth spurt, has a positive impact on adolescent bone markers despite the accumulated training load and maturation.

Growth, body composition and bone mineral density among pubertal male athletes: intra-individual 12-month changes and comparisons between soccer players and swimmers.

BACKGROUND: Puberty is a period of intense changes in human body and, additionally, participation in sports is viewed as prominent form of physical activity among male adolescent athletes. The current study was aimed to examine the intra-individual changes in body composition and bone tissue during years of maximal growth and the effect of 12-month participation in sports contrasting in mechanical impact. METHODS: The sample included 40 male adolescent athletes (soccer: n = 20; swimming: n = 20) aged 12.57 ± 0.37 years who were followed for 12 months. Stature and body mass were measured, bone mineral content (BMC), areal bone mineral density (aBMD), lean soft and fat tissues assessed using DXA. Food intake was estimated using a questionnaires and training sessions individually monitored. Repeated measures ANOVA tested the differences between sports and 12-month intra-individual variation (time moments: TM1, TM2). The analyses on aBMD for total body and total body less head were repeated controlling for variation in stature at baseline. RESULTS: Soccer players completed 63 ± 31 sessions (95 ± 47 h). Respective values for swimmers were 248 ± 28 sessions and 390 ± 56 h. In general, the analysis of aBMD as dependent variable evidenced significant effect of sport-associated variation (F = 5.254, p < 0.01; η2 = 0.35) and 12-month increments, particularly at lower limbs (F = 97.238, p < 0.01; η2 = 0.85). Respective mean values for aBMD were SCCTM1 = 0.885 g.cm-2, SWMTM1 = 0.847 g.cm-2, SCCTM2 = 0.939 g.cm-2, SWMTM2 = 0.880. Regarding the lean soft tissue, the magnitude of effects was very large for intra-individual variation (F = 223.043, p < 0.01; η2 = 0.92) and moderate between sports (F = 7.850, p < 0.01; η2 = 0.41): SCCTM1 = 30.6 kg, SWMTM1 = 34.9 kg, SCCTM2 = 35.8 kg, SWMTM2 = 40.5 kg). Finally, d-cohen values reporting percentage of intra-individual changes in aBMD between soccer players ad swimmers were large for the trochanter (d = 1.2; annual increments: SCC = 8.1%, SWM = 3.6%). CONCLUSION: Puberty appeared as a period of significant intra-individual changes in lean soft tissue and bone mineral density. With increasing accumulated training experience, mean difference between sports contrasting in mechanical impact tended to me more pronounced in particular at the lower limbs.

The Positive Relationship between Moderate-to-Vigorous Physical Activity and Bone Mineral Content Is Not Mediated by Free Leptin Index in Prepubertal Children: The PANIC Study.

PURPOSE: Moderate-to-vigorous physical activity (MVPA) positively influences bone mineral content (BMC) in prepubertal children, but it is unknown whether this relationship is partially mediated by free leptin index. The aim of this study was to examine whether the relationship between MVPA and total body less head (TBLH) BMC is mediated or moderated by free leptin index in prepubertal children. METHODS: We performed a cross-sectional analysis on 401 children (194 girls) from baseline examinations of the Physical Activity and Nutrition in Childhood Study. We applied the four-way decomposition mediation analysis method to assess whether free leptin index, measured from fasted blood samples, mediated the relationship between accelerometer-measured MVPA and TBLH BMC measured by dual-energy X-ray absorptiometry. RESULTS: MVPA had a positive controlled direct effect on TBLH BMC in girls and boys (ß = 0.010 to 0.011, p < 0.05). There was no mediation or interaction between MVPA, free leptin index and TBLH BMC in girls or boys (ß = -0.000 to 0.001, p > 0.05). CONCLUSION: Our study indicates that MVPA positively influences TBLH BMC through pathways not related to free leptin index in predominantly normal-weight prepubertal children, likely primarily through mechanical loading. The relationships between MVPA, free leptin index and TBLH BMC may be influenced by other factors such as pubertal status and adiposity, so it is unknown whether these observations extend to overweight and obese children at different stages of puberty.

The Mediating Role of Lean Soft Tissue in the Relationship between Somatic Maturation and Bone Density in Adolescent Practitioners and Non-Practitioners of Sports.

This study aimed to identify the mediating effect of lean soft tissue (LST) in the association between somatic maturation and areal bone mineral density (aBMD) in adolescents by sex and sport participation. The sample included 558 adolescents (401 males, mean age of 14.0 years) that were practitioners of sports (11 sport modalities, n = 402) and a non-sport group (n = 157). Somatic maturation was assessed by using a validated peak height velocity prediction equation. Dual-energy X-ray absorptiometry (DXA) was used to assess aBMD (upper and lower limbs, spine and total body less head-TBLH) and LST. For both sexes, LST mediated the association between somatic maturation and aBMD at all skeletal sites (mediation percentage ranging from 36.3% to 75.4%). For sport and non-sport groups, the LST also mediated the association between somatic maturation and aBMD at all skeletal sites (mediation percentage ranging from 51.6% to 85.6%). The direct effect was observed in all groups, except for lower limbs and TBLH in the non-sport group. The association between somatic maturation and aBMD was mediated by LST in adolescents of both sexes and regardless of involvement in organized sports. Our findings highlighted the role of improving LST to mitigate the association of somatic maturation with aBMD.

Reproducibility and inter-observer agreement of Greulich-Pyle protocol to estimate skeletal age among female adolescent soccer players.

BACKGROUND: Skeletal age (SA) is considered the best method of assessing biological maturation. The aim of this study was to determine intra-observer (reproducibility) and inter-observer agreement of SA values obtained via the Greulich-Pyle (GP) method. In addition, the variation in calculated SAs by alternative GP protocols was examined. METHODS: The sample was composed of 100 Portuguese female soccer players aged 12.0-16.7 years. SAs were determined using the GP method by two observers (OB1: experience < 100 exams using GP; OB2: experience > 2000 exams using several methods). The radiographs were examined using alternative GP protocols: (wholeGP) the plate was matched to the atlas as an overall approach; (30-boneGP) bone-by-bone inspections of 30-bones; (GPpmb) bone-by-bone inspections of the pre-mature bones only. For the 30-boneGP and GPpmb approaches, SA was calculated via the mean (M) and the median (Md). RESULTS: Reproducibility ranged 82-100% and 88-100% for OB1 and OB2, respectively. Inter-observer agreement (100 participants multiplied by 30 bones) was 92.1%. For specific bones, agreement rates less than 90% were found for scaphoid (81%), medial phalange V (83%), trapezium (84%) and metacarpal V (87%). Differences in wholeGP SAs obtained by the two observers were moderate (d-cohen was 0.79). Mean differences between observers when using bone-by bone SAs were trivial (30-boneGP: d-cohen less than 0.05; GPpmb: d-cohen less than 0.10). The impact of using the mean or the median was negligible, particularly when analyses did not include bones scored as mature. CONCLUSION: The GP appeared to be a reasonably reproducible method to assess SA and inter-observer agreement was acceptable. There is evidence to support a recommendation of only scoring pre-mature bones during later adolescence. Further research is required to examine whether these findings are consistent in younger girls and in boys.

Basketball players possess a higher bone mineral density than matched non-athletes, swimming, soccer, and volleyball athletes: a systematic review and meta-analysis.

Basketball athletes possess a higher bone mineral density (BMD) than matched non-athletes and swimming, soccer, and volleyball athletes. Differences appear to be exacerbated with continued training and competition beyond adolescence. The greater BMD in basketball athletes compared to non-athletes, swimming, and soccer athletes is more pronounced in males than females. PURPOSE: The aim of this study was to examine differences in total and regional bone mineral density (BMD) between basketball athletes, non-athletes, and athletes competing in swimming, soccer, and volleyball, considering age and sex. METHODS: PubMed, MEDLINE, ERIC, Google Scholar, and Science Direct were searched. Included studies consisted of basketball players and at least one group of non-athletes, swimming, soccer, or volleyball athletes. BMD data were meta-analyzed. Cohen's d effect sizes [95% confidence intervals (CI)] were interpreted as: trivial ≤ 0.20, small = 0.20-0.59, moderate = 0.60-1.19, large = 1.20-1.99, and very large ≥ 2.00. RESULTS: Basketball athletes exhibited significantly (p < 0.05) higher BMD compared to non-athletes (small-moderate effect in total-body: d = 1.06, CI 0.55, 1.56; spine: d = 0.67, CI 0.40, 0.93; lumbar spine: d = 0.96, CI 0.57, 1.35; upper limbs: d = 0.70, CI 0.29, 1.10; lower limbs: d = 1.14, CI 0.60, 1.68; pelvis: d = 1.16, CI 0.05, 2.26; trunk: d = 1.00, CI 0.65, 1.35; and femoral neck: d = 0.57, CI 0.16, 0.99), swimming athletes (moderate-very large effect in total-body: d = 1.33, CI 0.59, 2.08; spine: d = 1.04, CI 0.60, 1.48; upper limbs: d = 1.19, CI 0.16, 2.22; lower limbs: d = 2.76, CI 1.45, 4.06; pelvis d = 1.72, CI 0.63, 2.81; and trunk: d = 1.61, CI 1.19, 2.04), soccer athletes (small effect in total-body: d = 0.58, CI 0.18, 0.97), and volleyball athletes (small effect in total-body: d = 0.32, CI 0.00, 0.65; and pelvis: d = 0.48, CI 0.07, 0.88). Differences in total and regional BMD between groups increased with age and appeared greater in males than in females. CONCLUSION: Basketball athletes exhibit a greater BMD compared to non-athletes, as well as athletes involved in swimming, soccer, and volleyball.

Physiological profile of adult male long-distance trail runners: variations according to competitive level (national or regional).

OBJECTIVE: To describe and identify the importance of different indicators of the aerobic and anaerobic fitness of male ultra-trail runners according to their level of participation (regional or national). METHODS: Forty-four male ultra-trail runners were assessed (36.5±7.2 years). They were classified as regional (n=25) and national (n=19). Wingate test was used to assess the anaerobic pathway. A progressive incremental running test was performed and ventilatory thresholds registered, in parallel to heart rate and lactate concentration at the end of the protocol. Comparison between groups was performed using independent samples t-test. RESULTS: No significant differences were found between outputs derived from Wingate test. For aerobic fitness, while examining absolute values, differences were uniquely significant for the second ventilatory threshold (ultra-trail regional runners: 3.78±0.32L.min-1; ultra-trail national runners: 4.03±0.40L.min-1 p<0.05). Meantime, when aerobic fitness was expressed per unit of body mass, differences were significant for the second ventilatory threshold (ultra-trail regional runners: 50.75±6.23mL.kg-1.min-1; ultra-trail national runners: 57.88±4.64mL.kg-1.min-1 p<0.05) and also maximum volume of oxygen (ultra-trail regional runners: 57.33±7.66mL.kg-1.min-1; ultra-trail national runners: 63.39±4.26mL.kg-1.min-1 p<0.05). CONCLUSION: This study emphasized the importance of expressing physiological variables derived from running protocols per unit of body mass. Also, the second ventilatory threshold appears to be the best and the only aerobic fitness variable to distinguish between trail runners according to competitive level. Maximal oxygen uptake seems of relative interest to distinguish between long distance runners according to competitive level.

Bone Mineral Density and Sports Participation.

The objective of our study was to identify differences in bone mineral density (BMD) according to different sports among adolescents, as well as to identify assessments of relevant mediators. The sample consisted of 429 adolescents with a mean age of 13.3 ± 1.7 yr. The sports modalities that we evaluated were judo, karate, kung fu, swimming, basketball, and soccer. Nonsports group was composed of 111 adolescents. Bone density was assessed using dual-energy X-ray absorptiometry. Regarding BMD values, female engaged in karate had higher BMD values than girls from the no sports group (p = 0.01). Boys engaged in soccer and karate presented the highest BMD values than all the other groups (p = 0.01). The most relevant mediators were the body mass index and lean soft tissue for boys and girls. Different sports presented different results regarding BMD gains, which were influenced by body mass index and whole-body lean soft tissue.

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.

Physiological profile of adult male long-distance trail runners: variations according to competitive level (national or regional) / Perfil fisiológico de corredores de trilhas de longa distância adultos do sexo masculino: variações segundo o nível competitivo (nacional ou regional)

ABSTRACT Objective To describe and identify the importance of different indicators of the aerobic and anaerobic fitness of male ultra-trail runners according to their level of participation (regional or national). Methods Forty-four male ultra-trail runners were assessed (36.5±7.2 years). They were classified as regional (n=25) and national (n=19). Wingate test was used to assess the anaerobic pathway. A progressive incremental running test was performed and ventilatory thresholds registered, in parallel to heart rate and lactate concentration at the end of the protocol. Comparison between groups was performed using independent samples t-test. Results No significant differences were found between outputs derived from Wingate test. For aerobic fitness, while examining absolute values, differences were uniquely significant for the second ventilatory threshold (ultra-trail regional runners: 3.78±0.32L.min-1; ultra-trail national runners: 4.03±0.40L.min-1 p<0.05). Meantime, when aerobic fitness was expressed per unit of body mass, differences were significant for the second ventilatory threshold (ultra-trail regional runners: 50.75±6.23mL.kg-1.min-1; ultra-trail national runners: 57.88±4.64mL.kg-1.min-1 p<0.05) and also maximum volume of oxygen (ultra-trail regional runners: 57.33±7.66mL.kg-1.min-1; ultra-trail national runners: 63.39±4.26mL.kg-1.min-1 p<0.05). Conclusion This study emphasized the importance of expressing physiological variables derived from running protocols per unit of body mass. Also, the second ventilatory threshold appears to be the best and the only aerobic fitness variable to distinguish between trail runners according to competitive level. Maximal oxygen uptake seems of relative interest to distinguish between long distance runners according to competitive level.

RESUMO Objetivo Descrever e comparar indicadores de aptidão metabólica em corredores de trilhas de longa distância (ultra trail running) adultos do sexo masculino, de acordo com o nível de competição (regional ou nacional). Métodos Foram avaliados 44 corredores masculinos com média de idade de 36,5±7,2 anos classificados como de nível regional (n=25) ou nacional (n=19). Foi utilizado o teste de Wingate para avaliação da via anaeróbica, enquanto o teste incremental de corrida em esteira também foi realizado para determinar os limiares ventilatórios, o consumo máximo de oxigênio, a frequência cardíaca e a concentração de lactato ao final do protocolo. A comparação entre os grupos foi realizada por estatística teste t para amostras independentes. Resultados As variáveis obtidas do teste Wingate não diferiram de forma significativa entre os grupos. No que diz respeito à aptidão aeróbica, foram encontradas diferenças significativas entre variáveis expressas em valores absolutos no segundo limiar ventilatório (corredores de nível regional: 3,78±0,32L.min-1; corredores de nível nacional: 4,03±0,40L.min-1; p<0,05). Quando considerados os valores expressos por unidade de massa corporal, o segundo limiar ventilatório (corredores de nível regional: 50,75±6,23mL.kg-1.min-1; corredores de nível nacional: 57,88±4,64mL.kg-1.min-1; p<0,05) e o volume máximo de oxigênio (corredores de nível regional: 57,33±7,66mL.kg-1.min-1; corredores de nível nacional: 63,39±4,26mL.kg-1.min-1; p<0,05) também diferiram de forma significativa. Conclusão Este estudo destacou a importância de se expressarem variáveis fisiológicas derivadas de protocolos de corrida por unidade de massa corporal. Além disso, o segundo limiar ventilatório pareceu ser o melhor e único indicador de aptidão aeróbica para a diferenciação de corredores de trilha de longa distância, segundo o nível competitivo. O consumo máximo de oxigênio não é especialmente relevante para distinguir os corredores de trilha de longa distância, segundo o nível competitivo.

The effects of physical activity during childhood, adolescence, and adulthood on cardiovascular risk factors among adults.

OBJECTIVES: To analyze the association between physical activity during life and cardiovascular risk factors among adults. DESIGN: The sample was composed of 101 adults (59 men) between 30 and 50 years old, who were recruited from different gyms and from a University in Brasil. Participants were divided according to their engagement in sports in early life (self-reported) and current physical activity (pedometer) (sports participation during childhood/adolescence and currently active [n=26], sports participation during childhood/adolescence and currently inactive [n=26], and control [n=49]). Cardiovascular risk factors were measured, such as body fat (through DXA), HDL-C, triglycerides, HOMA index, systolic blood pressure, diastolic blood pressure, and C-reactive protein. We adopted the covariates of chronological age, sex, alcohol consumption, tobacco, and body mass index. General estimating equations were used, with p<0.05. RESULTS: After the adjustments of the final model, individuals engaged in sports during childhood and adolescence and inactive during adulthood presented lower body fat, when compared to participants persistently inactive (p<0.001). Participants persistently active presented lower body fat (p<0.001) and lower c-reactive protein (p=0.010) when compared to the control group. CONCLUSION: Early sports participation was associated with reduced body fat, and being physically active throughout life was associated with reduced body fat and C-reactive protein.

The effects of physical activity during childhood, adolescence, and adulthood on cardiovascular risk factors among adults

SUMMARY OBJECTIVES: To analyze the association between physical activity during life and cardiovascular risk factors among adults. DESIGN: The sample was composed of 101 adults (59 men) between 30 and 50 years old, who were recruited from different gyms and from a University in Brasil. Participants were divided according to their engagement in sports in early life (self-reported) and current physical activity (pedometer) (sports participation during childhood/adolescence and currently active [n=26], sports participation during childhood/adolescence and currently inactive [n=26], and control [n=49]). Cardiovascular risk factors were measured, such as body fat (through DXA), HDL-C, triglycerides, HOMA index, systolic blood pressure, diastolic blood pressure, and C-reactive protein. We adopted the covariates of chronological age, sex, alcohol consumption, tobacco, and body mass index. General estimating equations were used, with p<0.05. RESULTS: After the adjustments of the final model, individuals engaged in sports during childhood and adolescence and inactive during adulthood presented lower body fat, when compared to participants persistently inactive (p<0.001). Participants persistently active presented lower body fat (p<0.001) and lower c-reactive protein (p=0.010) when compared to the control group. CONCLUSION: Early sports participation was associated with reduced body fat, and being physically active throughout life was associated with reduced body fat and C-reactive protein.

RESUMO OBJETIVO: Analisar a associação entre atividade física durante a vida e fatores de risco cardiovasculares entre adultos. DESIGN: A amostra foi composta por 101 adultos (59 homens) entre 30 e 50 anos, os quais foram recrutados em diferentes academias de ginástica e uma universidade brasileira. Os participantes foram divididos de acordo com o engajamento prévio (autorrelatado) e atual de atividade física (mensurada por pedômetro) (participação esportiva durante a infância/adolescência e prática atual [n=26], participação esportiva durante a infância/adolescência e ausência de prática atual [n=26] e controle [n=49]). Como fatores de risco cardiovasculares foram mensurados gordura corporal (por meio de DXA), HDL, triglicérides, índice Homa, pressão arterial sistólica e diastólica, além da proteína c-reativa. Foram adotadas como covariáveis: idade cronológica, sexo, consumo de álcool e índice de massa corporal. Equações gerais de estimativa foram utilizadas adotando p<0,05. RESULTADOS: Após os ajustes no modelo final, indivíduos engajados em esporte durante a infância e adolescência e inativos durante a idade adulta apresentaram menor gordura corporal quando comparados com participantes persistentemente inativos (p<0,001). Participantes persistentemente ativos apresentaram menor gordura corporal (p<0,001) e proteína c-reativa (p=0,010) quando comparados ao grupo controle. CONCLUSÃO: Prática esportiva prévia (durante infância e adolescência) foi associada com redução da gordura corporal e ser fisicamente ativo ao longo da vida foi associado à redução da gordura corporal e proteína c-reativa.

Sports Participation Decreases the Incidence of Traumatic, Nonsports-Related Fractures Among Adolescents.

OBJECTIVES: To investigate the effects of different sports on the incidence of traumatic fractures (TF; sport-related fractures and those occurring in daily activities) among adolescents during the 9-month follow-up period. METHODS: The adolescents were contacted in 11 different locations (3 public/private schools and 8 sports clubs), and the final sample was divided into 3 groups: control (n = 121), swimming (n = 51), and impact sports (n = 142). The incidence of TF was calculated by considering the exposure to sports (TF/1000 h). RESULTS: In the overall sample, the incidence of TF was 1.29 TF/1000 hours of sports exposure, while the incidence of sport-related TF was 0.39 TF/1000 hours of sports exposure. Adolescents engaged in sports (P = .004), independently of type (P = .001), for 3 or more days per week (P = .004) and more than 60 minutes per day (P = .001) had lower incidence of TF. Adolescents engaged in more than 300 minutes per week of sport (0.17 TF/1000 h) had lower incidence than those who did not (2.06 TF/1000 h [P = .001]). A similar finding was observed for sport-related TF (≥300 min/wk: 0.08 TF/1000 h vs 300 min/wk: 0.615 TF/1000 h [P = .02]). CONCLUSION: Adolescents engaged in sports showed a lower incidence of TF than nonengaged adolescents.

Association between Sports Participation in Early Life and Arterial Intima-Media Thickness among Adults.

Background: Early sports practice is associated with several health benefits during childhood and adolescence, moreover, recent evidence also suggests that sports during childhood and adolescence can produce some benefits during adulthood. However, the association between early sports practice and arterial thickness is not clear. Thus, our aim was analyze the association between sports participation in childhood and adolescence, carotid/femoral intima⁻media thickness, and blood flow index in adulthood. Material and Methods: Sample was composed of 107 adults (64 males) between 30 years and 50 years, which were recruited from different gyms and university staff from São Paulo State University. Participants were divided according to sports participation in early life (engaged in sports during childhood and adolescence (n = 52) and no engagement in sports during childhood and adolescence (n = 55)). Carotid and femoral intima⁻media thickness were measured through Doppler ultrasonography method. Carotid and femoral index were estimated from ultrasonography measures. As covariates, the following were adopted: chronological age, sex, body fat (through dual-energy x-ray absorptiometry), c-reactive protein, HOMA, alcohol consumption, tobacco smoking, mean arterial pressure and current physical activity (pedometer). General estimating equations were used, adopting p < 0.05. Results: In the adjusted analyses, early sports participation was associated with lower carotid intima⁻media index (early sports participation: 0.64 mm ± 0.14 mm vs. no early sports participation: 0.71 mm ± 0.21 mm; p = 0.011), but not associated with femoral intima⁻media thickness, carotid resistive index and femoral resistive index after the adjustment by potential confounders. Conclusions: Sports participation in childhood and adolescence was associated with a reduced carotid intima⁻media thickness, independently of relevant confounders.

Relationship of Parental and Adolescents' Screen Time to Self-Rated Health: A Structural Equation Modeling.

AIM: To investigate the association of parental and adolescents' screen time with self-rated health and to examine the mediating effects of psychosocial factors (social relationships and distress) on this association. METHOD: A cross-sectional study was conducted among 984 Brazilian adolescents (10- to 17-year-olds). Self-rated health, screen time (adolescents and parental), and perception of social relationships and distress were evaluated through self-report questionnaires. Structural equation modeling was adopted to investigate the pathways of the relationship between adolescents' screen time and self-rated health. RESULTS: Adolescents' screen time was directly and negatively related to self-rated health only in boys ( r = -0.158, p = .015). In girls, screen time was related to self-rated health through distress ( r = -0.188, p = .007) and social relationships ( r = 0.176, p = .008). The models fit was adequate (χ2/ df ≤ 3.0, root mean square error of approximation <0.08, comparative fit index >0.90, and Tucker-Lewis Index >0.90). CONCLUSIONS: Higher screen time was associated with poor self-rated health in boys, while in girls, psychosocial factors mediated the adverse relationships between screen time and self-rated health.

Impact of Martial Arts (Judo, Karate, and Kung Fu) on Bone Mineral Density Gains in Adolescents of Both Genders: 9-Month Follow-Up.

PURPOSE: To compare bone mineral density (BMD) gains in adolescents of both genders stratified according to different martial art styles in a 9-month follow-up study. METHODS: The longitudinal study consisted of 29 adolescents of both genders and age between 11 and 17 years stratified into a control group (not engaged in any sport) and 50 fighters (kung fu/karate, n = 29; judo, n = 21). All 79 subjects underwent anthropometric measures (weight, height, leg length, and height set) and dual-energy X-ray absorptiometry (BMD, in g/cm2) at 2 moments, baseline and 9 months later. Maturity offset (age at peak height velocity), lean soft tissue, chronological age, and resistance training were treated as covariates. RESULTS: Male judoists presented higher gains in BMD-spine [0.098 g/cm2 (95% confidence interval, 0.068-0.128)] than control group [0.040 g/cm2 (95% confidence interval, 0.011-0.069)] (post hoc test with P = .030). There was no effect of martial art on BMD gains among girls. Independently of gender, in all multivariate models, lean soft tissue constituted the most relevant covariate. CONCLUSIONS: Judo practice in adolescents affected the bone accrual significantly after 9-month follow-up compared with controls, mainly in boys.

Bone tissue, blood lipids and inflammatory profiles in adolescent male athletes from sports contrasting in mechanical load.

Exploring the effect of non-impact and impact sports is particular relevant to understand the interaction between skeletal muscle and bone health during growth. The current study aimed to compare total and regional bone and soft-tissue composition, in parallel to measurements of blood lipid and inflammatory profiles between adolescent athletes and non-athletes. Anthropometry, biological maturity, dual energy X-ray absorptiometry (DXA) scans, training load and lipid and inflammatory profiles were assessed in a cross-sectional sample of 53 male adolescents (20 non-athletes, 15 swimmers and 18 basketball players) aged 12-19 years. Multiple comparisons between groups were performed using analysis of variance, covariance and magnitude effects (ES-r and Cohen's d). The comparisons of controls with other groups were very large for high-sensitivity C-reactive protein (d range: 2.17-2.92). The differences between sports disciplines, regarding tissue outputs obtained from DXA scan were moderate for all variables except fat tissue (d = 0.4). It was possible to determine small differences (ES-r = 0.17) between controls and swimmers for bone area at the lower limbs (13.0%). In parallel, between swimmers and basketball players, the gradient of the differences was small (ES-r range: 0.15-0.23) for bone mineral content (24.6%), bone area (11.3%) and bone mineral density (11.1%) at the lower limbs, favoring the basketball players. These observations highlight that youth male athletes presented better blood and soft tissues profiles with respect to controls. Furthermore, sport-specific differences emerged for the lower limbs, with basketball players presenting higher bone mineral content, area and density than swimmers.

Impact sports and bone fractures among adolescents.

The objective of the present study was to investigate the effects of different sports on stress fractures among adolescents during a 9-month follow-up period. The sample was composed of 184 adolescents divided into three groups (impact sports [n = 102]; swimming [n = 35]; non-sports [n = 47]). The occurrence of stress fracture was reported by participants and coaches. As potential confounders we considered age, sex, resistance training, body composition variables and age at peak of height velocity. There were 13 adolescents who reported fractures during the 9-month period. Bone mineral density values were higher in adolescents engaged in impact sports (P-value = 0.002). Independently of confounders, the risk of stress fracture was lower in adolescents engaged in impact sports than in non-active adolescents (hazard ratio [HR] = 0.23 [95% confidence interval (CI) = 0.05 to 0.98]), while swimming practice was not associated to lower risk of fracture (HR = 0.49 [95% CI = 0.09 to 2.55]). In conclusion, the findings from this study indicate the importance of sports participation among adolescents in the reduction of stress fracture risk, especially with impact sports. More importantly, these results could be relevant for recognising adolescents in danger of not reaching their potential for peak bone mass and later an increased risk of fractures.

Immunometabolic Responses after Short and Moderate Rest Intervals to Strength Exercise with and without Similar Total Volume.

This study investigated the influence of short and moderate intervals of recovery with and without equated volume during an acute bout exhaustive strength exercise on metabolic, hormonal and inflammatory responses in healthy adults. Eight physically active men (23.5 ± 3.1) performed three randomized sequences: Short (70% of 1 RM with 30 s of rest); Moderate (70% of 1 RM with 90 s of rest); and Volume-Equated Short (70% of 1 RM with 30 s of rest between sets with a repetition volume equal to that performed in Moderate). All sequences of exercises were performed until movement failure in the squat, bench press and T-bar row exercises, respectively. Glucose, lactate, testosterone, IL-6, IL-10, IL-1ra, and MCP-1 levels were assessed at rest, immediate post-exercise, and 1 h post. There was a main effect of time for testosterone (p < 0.001). The post hoc indicated differences between post-exercise and rest and post-1 h and post-exercise (p < 0.001). Lactate increased post-exercise when compared to pre and post-1 h (p < 0.001) and maintained higher post-1 h in relation to rest. IL-6 was greater post-exercise than rest (p = 0.045) and post-1 h and rest (p = 0.020). IL-10 was greater post-exercise (p = 0.007) and post-1 h (p = 0.002) than rest. IL-1ra increased post-exercise in relation to rest (p = 0.003) and MCP-1 was greater post-exercise than rest (p < 0.001) and post-1 h (p = 0.043). There were no significant differences between conditions or interaction. Thus, both short and moderate intervals of recovery induced greater metabolic, hormonal and inflammatory responses after acute bout of exhaustive strength exercise in healthy adult.