Effects of cardiorespiratory fitness and body mass index on cardiometabolic risk factors in schoolchildren.

INTRODUCTION: High levels of physical fitness established during childhood and adolescence have been associated with positive effects on cardiometabolic risk factors (CMRF), which persist into adulthood. Conversely, a sedentary lifestyle, overweight, and obesity during this period are considered public health problems. These conditions tend to worsen in adulthood, increasing the incidence of chronic diseases, deteriorating CMRF, and consequently leading to higher comorbidity and mortality rates. OBJECTIVE: To investigate the effect of cardiorespiratory fitness (CRF) and body mass index (BMI) on CMRF in children and adolescents. METHODS: The sample consisted of 49 schoolchildren of both sexes aged 10-17 years. Anthropometric assessments, CRF test, muscle strength test, and blood pressure (BP) measurement were conducted. Participants were allocated into groups based on BMI (eutrophic, overweight, obese), and CRF levels (low-fit, normal-fit, and high-fit). RESULTS: Obese individuals had lower CRF values compared to the eutrophic and overweight groups. The cardiometabolic risk profile (CMRP) was significantly higher in the obese group compared to the eutrophic group but showed no significant difference compared to the overweight group. The hight-fit group had lower CMRP values compared to the low-fit group. CONCLUSIONS: Higher BMI and CRF values had negative and positive effects on CMRF and CMRP in schoolchildren, respectively. Overweight or obese schoolchildren with low levels of CRF constitute an unfavourable cardiometabolic risk profile.

Effects of eccentric-emphasized leg curl intervention on muscle strength imbalance markers in professional soccer players during pre-season.

BACKGROUND: The effects of strength training on muscle strength imbalance are unclear in professional soccer players. As a result, this study examined the effects of an 8-week strength training program comprising eccentric-emphasized prone leg curl adjusted according to the individual strength imbalance status. METHODS: Ten professional soccer players (26.0 ± 3.6 yrs) participated in the study. Players who had a ≥ 10% contralateral imbalance in knee flexors eccentric peak torque (n = 6) performed two additional repetitions per set in the low-strength limb (high-volume, HV) compared to the high-strength limb (low-volume, LV). Isokinetic concentric knee extension and concentric and eccentric knee flexion peak torque (PT) and derived contralateral imbalances and conventional and functional hamstring-to-quadriceps ratios (H:Q) were assessed at baseline and after 8 weeks. Differences at baseline were assessed using paired-sample T-tests, and a two-way (limb x time) repeated measures analysis of covariance (ANCOVA) for changes over time. RESULTS: A significant improvement in the eccentric knee flexion PT was observed in both limbs after 8 weeks (P < 0.05), with greater effects observed in the HV limb (25.0 N m, 95% CI: 15.1-34.9 N m). Significant decreases were also observed in the contralateral imbalances from concentric knee extension and flexion and eccentric knee flexion PT (P < 0.05). Differences were not observed in concentric knee extension and flexion PT (P > 0.05). CONCLUSIONS: A short-term eccentric-emphasized leg curl intervention adjusted by the initial knee flexors eccentric strength was an efficient method to improve knee flexors strength imbalance in professional soccer players.

Effects of a small-sided soccer program on health parameters in obese children / Efectos de un programa de fútbol reducido en los parámetros de salud de niños obesos / Efeitos de um programa de futebol reduzido sobre os parâmetros de saúde de crianças obesas

ABSTRACT Introduction: Childhood obesity is increasing and, as a consequence, it generates health complications resulting from sedentary behavior and low levels of physical fitness. There are few studies involving children, metabolic and cardiorespiratory profiles, and soccer. Objective: The purpose was to measure the effects of a 12-week recreational small-sided soccer program on cardiometabolic risk and individual responses to cardiometabolic risk factors in overweight or obese boys. Methods: Thirteen boys aged 8-12 years (34.9±11.6% body fat) participated in a 12-week recreational small-sided soccer training program with two 80-minute sessions per week at intensities over 80% of the maximal heart rate. Anthropometric characteristics, cardiorespiratory fitness, metabolic profile, individual responses to peak oxygen uptake (VO2peak), maximal workload (Wmax), fasting blood glucose, insulin, HOMA-IR, LDL-C, HDL-C, TC, and TG were measured both pre- and post-training. Results: Considering the individual responses of the participants, recreational soccer training was effective in improving variations in maximum power and exhaustion time, as well as promoting at least one beneficial change in cardiometabolic risk factors in 84% of the overweight or obese children. There were no differences between pre- and post-program anthropometric characteristics, metabolic profiles, or VO2peak values. Conclusion: Twelve-week recreational small-sided soccer programs were able to improve maximal power and anaerobic capacity and maintain cardiometabolic risk factor levels in overweight and obese boys. Level of evidence I; High-quality prospective study (all patients were enrolled at the same stage of disease, with >80% of patients enrolled) .

RESUMEN Introdução: La obesidad infantil está aumentando y, como consecuencia, genera complicaciones de salud derivadas del comportamiento sedentario y de los bajos niveles de aptitud física. Existen pocos estudios sobre niños, perfiles metabólicos, cardiorrespiratorios y fútbol. Objetivo: El objetivo fue medir los efectos de un programa de fútbol recreativo reducido de 12 semanas sobre el riesgo cardiometabólico y respuestas individuales en niños con sobrepeso u obesos. Métodos: Trece niños de 8 a 12 años (34,9 ± 11,6% de grasa corporal) participaron en un programa de entrenamiento de fútbol recreativo reducido de 12 semanas con dos sesiones de 80 minutos por semana a intensidades superiores al 80% de la frecuencia cardíaca máxima. Se midieron las características antropométricas, la aptitud cardiorrespiratoria, el perfil metabólico y las respuestas individuales del consumo máximo de oxígeno (VO2pico), la carga de trabajo máxima (Wmax), la glucemia y la insulina en ayunas, HOMA-IR, LDL-C, HDL-C, CT y TG antes y después del entrenamiento. Resultados: Teniendo en cuenta las respuestas individuales, el entrenamiento de fútbol recreativo fue eficaz para mejorar las variaciones de potencia máxima y el tiempo hasta el agotamiento, así como para promover al menos un cambio beneficioso en los factores de riesgo cardiometabólico en el 84% de los niños con sobrepeso u obesidad. No hubo diferencias entre las características antropométricas, los perfiles metabólicos o el pico de VO2 antes y después del programa. Conclusões: Doce semanas de programas de fútbol recreativo reducido fueron capaces de mejorar la potencia máxima y la capacidad anaeróbica, así como de mantener los niveles de factores de riesgo cardiometabólicos en niños con sobrepeso y obesidad. Nível de evidência I; Estudo prospectivo de alta qualidade (todos os pacientes foram inscritos no mesmo estágio da doença, com > 80% dos pacientes inscritos) .

RESUMO Introdução: A obesidade infantil está aumentando e, como consequência, gera complicações de saúde decorrentes do comportamento sedentário e baixos níveis de aptidão física. Existem poucos estudos que envolvem crianças, perfis metabólicos e cardiorrespiratórios e futebol. Objetivo: O objetivo foi medir os efeitos de um programa de futebol recreativo reduzido de 12 semanas sobre o risco cardiometabólico e respostas individuais em meninos com sobrepeso ou obesos. Métodos: Treze meninos de 8 a 12 anos (34,9 ± 11,6% de gordura corporal) participaram de um programa de treinamento de futebol recreativo reduzido de 12 semanas com duas sessões de 80 minutos por semana em intensidades acima de 80% da frequência cardíaca máxima. As características antropométricas, a aptidão cardiorrespiratória, o perfil metabólico e as respostas individuais do pico de consumo de oxigênio (VO2pico), carga máxima de trabalho (Wmáx), glicemia e insulina em jejum, HOMA-IR, LDL-C, HDL-C, CT e TG foram medidos pré e pós-treinamento. Resultados: considerando as respostas individuais dos participantes, o treinamento recreativo de futebol foi eficaz para melhorar as variações da potência máxima e do tempo até a exaustão, bem como promover pelo menos uma alteração benéfica nos fatores de risco cardiometabólico em 84% das crianças com sobrepeso ou obesidade. Não houve diferenças entre as características antropométricas pré e pós-programa, perfis metabólicos ou VO2pico. Conclusões: Doze semanas de programas de futebol recreativo reduzido foram capazes de melhorar a potência máxima e a capacidade anaeróbica, bem como manter os níveis de fatores de risco cardiometabólicos em meninos com sobrepeso e obesos. Nível de evidência I; Estudo prospectivo de alta qualidade (todos os pacientes foram inscritos no mesmo estágio da doença, com > 80% dos pacientes inscritos) .

Interindividual variability of adaptations following either traditional strength or power training combined to endurance training in older men: A secondary analysis of a randomized clinical trial.

This study aimed to investigate the interindividual responses following two different concurrent training (CT) regimens in neuromuscular, cardiorespiratory and functional outcomes of older men. Thirty-five older men (65.8 ± 3.9 years) were randomly allocated into one of two CT groups: power training (PT) + high-intensity interval training (HIIT) (n = 17); or traditional strength training (TST) + HIIT (n = 18). Maximal dynamic strength (one-repetition maximum, 1RM), rate of force development at 100 milliseconds (RDF100), countermovement jump power (CMJ), quadriceps femoris muscle thickness (QF MT), functional tests (sit-to-stand, timed-up-and-go, and stair climbing), and peak oxygen consumption (VO2peak) were assessed pre-, post-8 and post-16 weeks of training. The Chi-squared test was used for assessing differences in the prevalence of responders (Rs), non-responders (NRs), and adverse responders (ARs). Similar prevalence of individual responses (Rs, NRs and ARs) between groups were observed after intervention in almost all outcomes: 1RM; power at CMJ; QF MT, and functional tests (P > 0.05). However, a significant difference in the distribution of Rs, NRs and ARs between groups was observed in the RFD100 after 16 weeks (p = 0.003), with PT + HIIT group presenting high prevalence of Rs than TST + HIIT (100 % vs. 50 %). The inclusion of explosive-type of contractions in a concurrent training regime induces greater responsiveness in the RFD100 in older men, while no differences compared to traditional strength training are observed in maximal strength, muscle size, VO2peak, and functional performance.

Cardiometabolic health profile of young girls with aesthetic professions.

BACKGROUND: In the literature, professions that impose body standards for daily performance are designated as non-conventional professions (i.e. models, athletes, ballet dancers), with great emphasis on the female population. More than a job, it becomes a lifestyle to those inserted in this environment, thus, thousands of children and adolescents seek inclusion and success in these professions due to financial and media gains. Such professions are associated with several health-related risk factors. The purpose of this study was to identify and compare among physical fitness levels, cardiometabolic health markers, mental health and dietary habits in non-conventional professions. METHODS: The sample consisted of 41 female individuals aged between 14 and 24 years, allocated into four groups, control group composed by university students (UG = 11), models (MG = 11), ballet dancers (BG = 11), and athletes' group (AG = 8). Physical fitness outcomes (cardiorespiratory fitness, flexibility, maximal dynamic strength, muscular endurance and body composition); biochemical outcomes (high-density lipoprotein [HDL], low-density lipoprotein [LDL], total cholesterol [TC], fasting glucose [FG], fasting insulin [FI], C-reactive protein [CRP]), diet quality and mental health were evaluated. RESULTS: No impairments were observed in the health markers evaluated among groups, both for health-related physical fitness and biochemical outcomes. However, low levels of bone mineral density (BMD) were observed. Even with statistically significant differences between the groups for chronological age (p = 0.002), menarche (p = 0.004), career length (p = 0.001), height (p = 0.001), body mass index (p = 0.018), waist-to-height ratio (p < 0.001), %Fat (p = 0.020), VO2peak (p = 0.020), maximal dynamic strength of knee extensors (p = 0.031) and elbow flexors (p = 0,001) and flexibility (p < 0.001), all these values are within the normal range for health. CONCLUSION: The professions analyzed do not seem to interfere in the physical fitness and cardiometabolic health of the girls assessed. However, we identified that exposure to these profession can impair mental health (depressive symptoms in 100% of participants) and body composition (BMD 63% of participants).

Effects of high-intensity interval training combined with traditional strength or power training on functionality and physical fitness in healthy older men: A randomized controlled trial.

Concurrent training (CT) is an efficient strategy to improve neuromuscular function and cardiorespiratory fitness in older adults, which are factors of pivotal importance for the maintenance of functional capacity with aging. However, there is a lack of evidence about the effectiveness of power training (PT) as an alternative to traditional strength training (TST) during CT. Thus, the aim of the present study was to examine the effect of 16 weeks (twice weekly) TST combined with high intensity interval training (TST + HIIT) vs. PT combined with HIIT (PT + HIIT) on functional performance, cardiorespiratory fitness and body composition in older men. Thirty five older men (65.8 ± 3.9 years) were randomly allocated into two training groups: TST + HIIT (n = 18), and PT + HIIT (n = 17). TST + HIIT performed resistance training at intensities ranging from 65% to 80% 1RM at slow controlled speed (≅ 2 s for each concentric phase), whereas PT + HIIT trained at intensities ranging from 40% to 60% of 1RM at maximal intentional speed. Both groups performed HIIT at intensities ranging from 75 to 90% of VO2peak. Participants performed functional tests (sit-to-stand, timed-up-and-go, stair climbing); cardiopulmonary exercise testing (maximal cycling power output: Wmax, peak oxygen uptake: VO2peak, cycling economy), as well as body composition assessment (DXA) before, post 8 and post 16 weeks of training. The groups improved similarly (P < 0.05) with training in all functional capacity outcomes, Wmax, cycling economy, VO2peak and body composition (P < 0.05). These findings suggest that HIIT based CT programs involving TST vs. PT are equally effective in improving functionality, cardiorespiratory fitness and body composition in healthy older men.

Maturity status effects on torque and muscle architecture of young soccer players.

This study investigated the effects of maturity status on knee extensor torque and vastus lateralis architecture of young soccer players. Thirty-four males aged 13-18 years were divided into two groups: pubescent (PUB, n = 15) and postpubescent (POSP, n = 19). Torque by angle interaction was established for absolute [F(2.649, 84.771) = 9.066, p < 0.05] and relative to body mass [F(2.704, 86.533) = 4.050, p < 0.05] isometric torque with the POSP group showing greater values. Muscle volume torque-angle relationship was similar between groups. Absolute, relative to body mass, and relative to muscle volume concentric and eccentric torque-velocity relationship showed a non-significant interaction but a significant group effect in favour the POSP group for absolute and concentric torque relative to body mass. Torque-angle and torque-velocity relationship normalized by body mass allometric exponents showed a non-significant interactions and group effects. Muscle thickness (3.6 ± 0.6 vs. 3.8 ± 0.6 cm), fascicle length (8.3 ± 1.4 vs. 8.9 ± 1.6 cm) and pennation angle (15.0 ± 2.3 vs. 14.3 ± 3.2 degrees) was similar between PUB and POSP groups, respectively. Maturity status did not show a significant effect on muscle architecture and on isometric and dynamic torques when allometrically normalized.

Functional and physiological adaptations following concurrent training using sets with and without concentric failure in elderly men: A randomized clinical trial.

This study compared the functional and physiological adaptations induced by concurrent training (CT) performed with repetitions to concentric failure and not to failure in elderly men. Fifty-two individuals (66.2 ±â€¯5.2 years) completed the pre- and post-measurements and were divided into three groups: repetitions to failure (RFG, n = 17); repetitions not to failure (NFG, n = 20); and repetitions not to failure with total volume equalized to that in the RFG (ENFG, n = 15). The participants' sit-to-stand ability, timed-up-and-go (TUG), muscle power output in squat jump (SJ) and countermovement jump (CMJ), peak oxygen uptake (VO2peak), blood lipids and glucose, as well as blood pressure levels were assessed. A subsample of our participants (n = 22) also underwent assessment of body composition by dual X-ray absorptiometry (DXA). CT was performed twice weekly for over 12 weeks. In addition to the specific strength training (ST) programme, each group also underwent endurance training (ET) in the same session (i.e., ST immediately followed by ET). After training, all groups improved similarly and significantly in their sit-to-stand ability (P < 0.01), muscle power output relative to body mass in SJ and CMJ (P < 0.001), VO2peak (P < 0.01) and HDL cholesterol levels (P < 0.001). There were reductions in the total, leg and trunk percent fat mass as well as increases in the total, leg and trunk percent lean mass (P values ranging from P < 0.05 to P < 0.01). Independent of performing repetitions until concentric failure and greater ST volumes, all CT groups exhibited improved sit-to-stand ability, muscle power output, VO2peak and HDL cholesterol levels. In addition, our preliminary data suggest that there are no differences in the effects of the assessed CT approaches on body composition outcomes. We therefore highlight the need for additional well-powered studies to assess whether repetitions to failure could underlie distinct effects on body composition.

Effects of n-3 fatty acids and exercise on oxidative stress parameters in type 2 diabetic: a randomized clinical trial.

BACKGROUND: The relationship between diabetes and oxidative stress has been previously reported. Exercise represents a useful non-pharmacological strategy for the treatment in type 2 diabetic (T2DM) patients, but high intensity exercise can induce a transient inflammatory state and increase oxidative stress. Nutritional strategies that may contribute to the reduction of oxidative stress induced by acute exercise are necessary. The aim of this study was to examine if n-3 PUFA supplementation intervention can attenuate the inflammatory response and oxidative stress associated with high intensity exercise in this population. As a primary outcome, lipoperoxidation measurements (TBARS and F2-isoprostanes) were selected. METHODS: Thirty T2DM patients, without chronic complications, were randomly allocated into two groups: placebo (gelatin capsules) or n-3 PUFA (capsules containing 180 mg of eicosapentaenoic acid and 120 mg of docosahexaenoic acid). Blood samples were collected fasting before and after 8 weeks supplementation. In the beginning and at the end of protocol, an acute exercise was performed (treadmill), and new blood samples were collected before and immediately after the exercise for measurements of oxidative stress and high-sensitivity C-reactive protein (hs-CRP). RESULTS: After the supplementation period, a decrease in triglycerides levels was observed only in n-3 PUFA supplementation group (mean difference and 95% CI of 0.002 (0.000-0.004), p = 0.005). Supplementation also significantly reduced TRAP levels after exercise (mean difference and 95% CI to 9641 (- 20,068-39,351) for - 33,884 (- 56,976 - -10,793), p = 0.004, Cohen's d effect size = 1.12), but no significant difference was observed in n-3 PUFA supplementation group in lipoperoxidation parameters as TBARS (mean difference and 95% CI to - 3.8 (- 10-2.4) for - 2.9 (- 1.6-7.4) or F2-isoprostanes (mean difference and 95% CI -0.05 (- 0.19-0.10) for - 0.02 (- 0.19-0.16), p > 0.05 for both. CONCLUSION: PUFA n-3 supplementation reduced triglycerides as well as TRAP levels after exercise, without a significant effect on inflammatory and oxidative stress markers.This study is registered at ClinicalTrials.gov with the registration number of NCT03182712.

Interrelationships among Jumping Power, Sprinting Power and Pubertal Status after Controlling for Size in Young Male Soccer Players.

This study examined power output on jumping and sprinting tests in young soccer players of differing pubertal status, while controlling for body size with allometric scaling exponents. A total of 46 males aged 12-18 years (14.17 years) were divided into three groups: pre-pubescent ( n = 12), pubescent ( n = 22), and post-pubescent ( n = 12). Participants performed a series of tests, including the squat jump (SJ), countermovement jump (CMJ), and 10-meter and 30-meter sprint test protocols. The Post-PUB group was older ( F = 112.411, p < 0.001), more experienced in competitive soccer ( F = 8.055, p = 0.001), taller ( F = 28.940, p < 0.001), and heavier ( F = 20.618, p < 0.001), when compared to peers in the other groups. Mean differences in jumping and sprinting performances suggested a significant effect for pubertal status on performance in the 10-meter sprint (large effect size, F = 8.191, p < 0.001) and 30-meter sprint (large effect size, F = 8.093, p < 0.001) after allometric scaling. Power output derived from SJ (small effect size, F = 0.536, p = 0.001) and CMJ (small effect size, F = 1.058, p = 0.356) showed no significant differences across players of varying pubertal status. Biological maturation showed a large effect on maximal power output for sprints, but not for jumps, when the effect of body size was adjusted by statistically derived allometric exponents in young male soccer players.

Aerobic fitness profile of youth soccer players: effects of chronological age and playing position / Perfil aeróbio de jovens jogadores de futebol: efeitos da idade cronológica e da posição tática

Abstract To establish a profile of the aerobic fitness in young soccer players, it is critical to consider different intervenient factors such as maturity status, chronological age and playing position. The aim of this study was to identify the biological maturation, chronological age, and playing position effects on physical and physiological characteristics of young soccer players. Two hundred and one soccer players of 11-19 years old were divided into groups relative to their maturity status, chronological age and playing position. A maximal exercise test was performed to determine peak oxygen uptake (VO2peak) and ventilatory thresholds (VT1 and VT2) parameters in a treadmill. Biological maturation showed no significant effect on relative values (mL•kg-1•min-1) of VO2peak, VT2 and VT1 (0.004 < h2 < 0.039), but showed large positive effect on maximal aerobic speed (MAS) and speed at VT2 (VT2speed). Chronological age showed a medium positive effect on relative values of VO2peak, VT2 and VT1 (0.095 < h2 < 0.137) and a large positive effect on MAS and VT2speed. Relative values of VO2peak and VT1 showed no significant differences among groups for playing position (P>0.05; 0.044 < h2 < 0.051). However, goalkeepers showed significant lower relative values for VT2 and VT2speed than other playing positions and a medium positive effect was observed (P<0.05; 0.077 < h2 < 0.119). Chronological age showed a medium to large positive effect on aerobic fitness parameters, while biological maturation showed a positive effect only on MAS and VT2speed. Playing position showed a medium positive effect on VT2 and VT2speed.

Resumo Para identificar o perfil aeróbico de jovens jogadores de futebol é necessário considerar fatores intervenientes como maturação biológica, idade cronológica e posição tática. O objetivo do presente estudo foi identificar o efeito da maturação biológica, idade cronológica e posição tática sobre as características físicas e fisiológicas de jovens jogadores de futebol. Duzentos e um jogadores de futebol com idades entre 11-19 anos foram divididos em grupos de acordo com estágio maturacional, idade cronológica e posição tática. Um teste máximo foi realizado para determinar o consumo de oxigênio de pico (VO2pico) e limiares ventilatórios (LV1 e LV2). A maturação biológica não apresentou efeitos significativos sobre os valores relativos (mL•kg-1•min-1) de VO2pico, LV2 e LV1 (0,004 < η2 < 0,039), mas apresentou elevado efeito sobre velocidade aeróbia máxima (VAM) e velocidade em LV2 (LV2velocidade). A idade cronológica apresentou efeito positivo médio sobre os valores relativos de VO2pico, LV2 e LV1 (0,095 < η2 < 0,137), e elevado efeito positivo sobre VAM e LV2velocidade. A posição tática não apresentou diferenças significativas sobre os valores relativos de VO2pico e LV1 entre os grupos (P>0,05; 0,044 < η2 < 0,051). Entretanto, goleiros apresentaram significativamente menores valores relativos de LV2 e LV2velocidade em comparação com outras posições táticas, com efeito positivo médio sendo identificado (P<0,05; 0,077 < η2 < 0,119). A idade cronológica apresentou efeito positivo de médio a elevado sobre o perfil aeróbio, entretanto, a maturação biológica não apresentou efeito, exceto para VAM e LV2velocidade. A posição tática apresentou efeitos positivos sobre LV2 e LV2velocidade.

Energy substrate utilization with and without exogenous carbohydrate intake in boys and men exercising in the heat.

Little is known about energy yield during exercise in the heat in boys compared with men. To investigate substrate utilization with and without exogenous carbohydrate (CHOexo) intake, seven boys [11.2 ± 0.2 (SE) yr] and nine men (24.0 ± 1.1 yr) cycled (4 × 20-min bouts) at a fixed metabolic heat production (Hp) per unit body mass (6 W/kg) in a climate chamber (38°C and 50% relative humidity), on two occasions. Participants consumed a 13C-enriched 8% CHO beverage (CARB) or placebo beverage (CONT) in a double-blinded, counterbalanced manner. Substrate utilization was calculated for the last 60 min of exercise. CHOexo oxidation rate (2.0 ± 0.3 vs. 2.5 ± 0.2 mg·kg fat-free mass-1·min-1, P = 0.02) and CHOexo oxidation efficiency (12.8 ± 0.6 vs. 16.0 ± 0.9%, P = 0.01) were lower in boys compared with men exercising in the heat. Total carbohydrate (CHOtotal), endogenous CHO (CHOendo), and total fat (Fattotal) remained stable in boys and men (P > 0.05) during CARB, whereas CHOtotal oxidation rate decreased (P < 0.001) and Fattotal oxidation rate increased over time similarly in boys and men during CONT (P < 0.001). The relative contribution of CHOexo to total energy yield increased over time in both groups (P < 0.001). In conclusion, endogenous substrate metabolism and the relative contribution of fuels to total energy yield were not different between groups. The ingestion of a CHO beverage during exercise in the heat may be as beneficial for boys as men to spare endogenous substrate.

Thermoregulation in boys and men exercising at the same heat production per unit body mass.

PURPOSE: Child-adult thermoregulatory comparisons may be biased by differences in metabolic heat production ([Formula: see text]). We compared thermoregulatory responses of boys and men exercising at two intensities prescribed to elicit either a fixed [Formula: see text] per unit body mass (BM) or a fixed absolute [Formula: see text]. METHODS: Ten boys (10-12 years) and 10 men (19-25 years) performed 4 × 20-min cycling at a fixed [Formula: see text] per BM (W kg(-1)) at 35 °C and 35 % relative humidity (MENREL). Men also cycled (MENABS) at the same absolute [Formula: see text] (in W) as the boys. RESULTS: [Formula: see text] was lower in boys compared with MENREL, but similar to MENABS (mean ± SD, 233.6 ± 38.4, 396.5 ± 72.3, 233.6 ± 34.1 W, respectively, P < 0.001). Conversely, [Formula: see text] per unit BM was similar between boys and MENREL, and lower in MENABS (5.7 ± 1.0, 5.6 ± 0.8 and 3.3 ± 0.3 W kg(-1), respectively; P < 0.001). The change in rectal temperature was similar between boys and MENREL (0.6 ± 0.2 vs. 0.7 ± 0.2 °C, P = 0.92) but was lower in MENABS (0.3 ± 0.2 °C, P = 0.004). Sweat volume was lower in boys compared to MENABS (500 ± 173 vs. 710 ± 150 mL; P = 0.041), despite the same evaporative heat balance requirement (E req) (199.1 ± 34.2 vs. 201.0 ± 32.7 W, P = 0.87). CONCLUSION: Boys and men demonstrated similar thermoregulatory responses to 80 min of exercise in the heat performed at a fixed [Formula: see text] per unit BM. Sweat volume was lower in boys compared to men, despite similarities in absolute [Formula: see text] and E req.

Thermoregulation of competitive artistic gymnastic athletes and non-athlete girls exercising in the heat / Termorregulação em atletas de ginástica artística e meninas não-atletas durante exercício no calor

Abstract It’s unclear whether the combination of intense, chronic training and heat exposure during prepubescence improves thermoregulatory responses to exercise in artistic gymnastics athletes. The objective of this study was to compare thermoregulatory and perceptual responses between artistic gymnastics athletes and non-athlete girls while exercising both in heat and thermoneutral conditions. Seven athletes (8.7 ± 1.3 yrs) and 7 nonathletes (9.4 ± 1.5 yrs) cycled for 30 min at load (W) of ~55% VO2peak, on two separate occasions in a randomized order: heat (35˚C, 40% relative humidity) and thermoneutral conditions (24˚C, 50% relative humidity). Rectal temperature, heart rate, rate of perceived exertion, thermal sensation, thermal comfort and irritability were measured throughout the exercise. Initial rectal temperature was similar between athletes and non-athletes in both heat (37.2 ± 0.4 vs. 37.4 ± 0.2˚C, respectively) and thermoneutral conditions (37.3 ± 0.2 vs. 37.3 ± 0.3˚C). Final rectal temperature was similar between groups (38.0 ± 0.2 vs. 38.2 ± 0.2˚C in heat and 37.8 ± 0.2 vs. 37.9 ± 0.2˚C in thermoneutral conditions). Initial heart rate was lower in athletes in the heat (76 ± 7 vs. 91 ± 11 bpm, P = 0.01); however, throughout cycling, it became similar between groups. Athletes reported similar perceptual responses compared to non-athletes, with the exception of higher thermal comfort in the 10th minute of exercise in thermoneutral conditions (P = 0.003). It was concluded that athletes were similar to non-athletes with respect to thermoregulatory and perceptual responses during 30 min of cycling at similar relative intensities.

Resumo Não está claro se a combinação de treinamento crônico intenso e a exposição ao calor durante a pré-adolescência melhoram as respostas termorregulatórias ao exercício em atletas de ginástica artística (GA). Objetivou-se comparar as respostas termorregulatórias e perceptivas entre atletas de GA e não-atletas durante uma sessão de exercício nas condições de calor (CC) e termoneutra (CT). Sete atletas (8,7 ± 1,3 anos) e 7 não-atletas (9,4 ± 1,5 anos) pedalaram por 30 minutos com carga (W) referente ~55% VO2pico, em CC (35˚C e 40% umidade relativa) e CT (24˚C e 50% umidade relativa). A temperatura retal (Tre), frequência cardíaca (FC), taxa de percepção de esforço, sensação e conforto térmico e irritabilidade foram medidas durante o exercício. Tre inicial foi similar entre atletas e não-atletas em CC (37,2 ± 0,4 vs. 37,4 ± 0.2˚C, respectivamente) e CT (37,3 ± 0,2 vs. 37,3 ± 0.3˚C). Tre final foi similar entre os grupos (38,0 ± 0,2 vs. 38,2 ± 0.2˚C na CC; e 37,8 ± 0,2 vs. 37,9 ± 0.2˚C na CT). FC inicial foi menor nas atletas na CC (76 ± 7 vs. 91 ± 11 bpm, P = 0,01). No entanto, ao longo das pedaladas, foi similar em ambos os grupos. As respostas perceptivas foram similares entre os grupos, com exceção ao maior conforto térmico das atletas aos 10 minutos de pedalada (P= 0,003). As atletas de GA apresentaram respostas termorregulatórias similares as não-atletas durante 30 minutos de pedalada em similar intensidade relativa nas CC e CT.

Maturity Status Does Not Exert Effects on Aerobic Fitness in Soccer Players After Appropriate Normalization for Body Size.

The present study investigated the effects of pubertal status on peak oxygen uptake (VO2peak), respiratory compensation point (RCP), and ventilatory threshold (VT) in young soccer players using different body size descriptors. Seventy-nine soccer players (14 prepubescent, 38 pubescent and 27 postpubescent) participated in this study. A maximal exercise test was performed to determine the VO2peak, RCP, and VT. Ultrasonography was used to measure lower limb muscle volume (LLMV). LLMV (mL-b) was rated as the most effective body size descriptor to normalize VO2peak (mLO2·mL-0.43·min-1), RCP (mLO2·mL-0.48·min-1), and VT (mLO2·mL- 0.40·min-1). The values of VO2peak, RCP, and VT relative to allometric exponents derived by LLMV were similar among groups (p > .05; 0.025 < η2 < 0.059) when the effect of chronological age was controlled. Allometric VO2peak, RCP, and VT values were: 100.1 ± 7.9, 107.5 ± 9.6, and 108.0 ± 10.3 mLO2.mL-0.43·min-1; 51.8 ± 5.3, 54.8 ± 4.7, and 57.3 ± 5.8 mLO2·mL-0.48·min-1; and 75.7 ± 7.1, 79.4 ± 7.0, and 80.9 ± 8.3 mLO2·mL- 0.40·min-1 for prepubertal, pubertal, and postpubertal groups, respectively. Maturity status showed no positive effect on VO2peak, RCP, and VT when the data were properly normalized by LLMV in young soccer players. Allometric normalization using muscle volume as a body size descriptor should be used to compare aerobic fitness between soccer players heterogeneous in chronological age, maturity status, and body size.

Effects of strength training, detraining and retraining in muscle strength, hypertrophy and functional tasks in older female adults.

INTRODUCTION: Previous studies presented different results regarding the maintenance time of muscular adaptations after strength training and the ability to resume the gains on muscular performance after resumption of the training programme. OBJECTIVE: This study aimed to verify the effect of strength training on knee extensors and elbow flexor muscle strength, rectus femoris muscle volume and functional performance in older female adults after 12 weeks of strength training, 1 year of detraining and followed by 12 weeks of retraining. METHODS: Twelve sedentary older women performed 12 weeks of strength training, 1 year of detraining and 12 weeks of retraining. The strength training was performed twice a week, and the assessment was made four times: at the baseline, after the strength training, after the detraining and after the retraining. The knee extensor and elbow flexor strength, rectus femoris muscle volume and functional task were assessed. RESULTS: Strength of knee extensor and elbow flexor muscles, rectus femoris muscle volume and 30-s sit-to-stand increased from baseline to post-training (respectively, 40%, 70%, 38% and 46%), decreased after detraining (respectively, -36%, -64%, -35% and -43%) and increased again these parameters after retraining (35%, 68%, 36% and 42%). CONCLUSION: Strength training induces gains on strength and hypertrophy, also increased the performance on functional tasks after the strength training. The stoppage of the strength caused strength loss and reduction of functional performance. The resumption of the strength training promoted the same gains of muscular performance in older female adults.

Physiological adaptations to resistance training in prepubertal boys.

PURPOSE: The purpose of this study was to investigate the physiological adaptations of resistance training (RT) in prepubertal boys. METHODS: Eighteen healthy boys were divided into RT (n = 9, Mage = 10.4 ± 0.5 years) and control (CTR; n = 9, Mage = 10.9 ± 0.7 years) groups. The RT group underwent a resistance training during 12 weeks, 3 times per week, performing 3 sets of 6 to 15 repetitions at intensities ranging from 60% to 80% of maximal dynamic strength (1-repetition maximum [1-RM] values). Before and after the training, the groups were assessed in their body mass and composition (dual-energy X-ray absorptiometry), isokinetic dynamometry, 1-RM, and ergoespirometry. Moreover, force per unit of muscle volume was calculated by the quotient between 1-RM and lean mass. RESULTS: Both groups presented statistically significant (p < .05) increases in the 1-RM and force per unit of muscle volume in the knee extension and elbow flexion, but these strength increases were statistically significantly greater in the RT group (effect size [ES] = 2.83-9.00) than in the CTR group (ES = 0.72-1.00). Moreover, both groups statistically significantly increased in lean body mass variables (ES = 0.12-0.38). However, increases in the fat mass variables occurred only in the CTR group (ES = - 0.01-0.50), whereas no changes were observed in the RT group. Furthermore, there were statistically significant increases in all bone mineral content variables (ES = 0.13-0.43), without differences between groups. No cardiorespiratory changes were observed. CONCLUSION: Twelve weeks of RT was effective in improving strength and force per unit of muscle volume and prevented fat mass increases in boys.

Oxygen consumption and heart rate responses to isolated ballet exercise sets.

Ballet stage performances are associated with higher cardiorespiratory demand than rehearsals and classes. Hence, new interest is emerging to create periodized training that enhances dancers' fitness while minimizing delayed exercise-induced fatigue and possible injuries. Finding out in what zones of intensity dancers work during different ballet movements may support the use of supplemental training adjusted to the needs of the individual dancer. Therefore, the main purpose of this study was to describe dancers' oxygen consumption (VO2) and heart rate (HR) responses during the performance of nine isolated ballet exercise sets, as correlated with their first and second ventilatory thresholds (VT1 and VT2). Twelve female ballet dancers volunteered for the study. Their maximum oxygen consumption (VO2max), VT1, and VT2 were determined by use of an incremental treadmill test. Nine sets of ballet movements were assessed: pliés, tendus, jetés, rond de jambes, fondus, grand adage (adage), grand battements, temps levés, and sautés. The sets were randomly executed and separated by 5 minute rest periods. ANOVA for repeated measurements followed by the Bonferroni Post-hoc test were applied (p < 0.05). VO2 responses were as follows: pliés (17.6 ± 1.6 ml·kg(-1)·min(-1)); tendus and adage were not significantly greater than VT1; rond de jambes (21.8 ± 3.1 ml·kg(-1) ·min(-1)); fondus and jetés were higher than VT1 and the previous exercises; grand battements (25.8 ± 2.9 ml·kg(-1)·min(-1)) was greater than all the other exercises and VT1; and VT2 was significantly higher than all ballet sets. This stratification followed closely, but not exactly, the variation in HR. For example, rond de jambes (156.8 ± 19 b·min(-1)) did not show any significant difference from all the other ballet sets, nor VT1 or VT2. It is concluded that the workloads of isolated ballet sets, based on VO2 responses, vary between low and moderate aerobic intensity in relation to dancers' VT1 and VT2. However, ballet set workloads may be higher when based on HR responses, due to the intermittent and isometric components of dance.

Serum S100B level increases after running but not cycling exercise.

The objective of this study was to investigate the effect of running versus cycling exercises upon serum S100B levels and typical markers of skeletal muscle damage such as creatine kinase (CK), aspartate aminotransferase (AST) and myoglobin (Mb). Although recent work demonstrates that S100B is highly expressed and exerts functional properties in skeletal muscle, there is no previous study that tries to establish a relationship between muscle damage and serum S100B levels after exercise. We conducted a cross-sectional study on 13 male triathletes. They completed 2 submaximal exercise protocols at anaerobic threshold intensity. Running was performed on a treadmill with no inclination (RUN) and cycling (CYC) using a cycle-simulator. Three blood samples were taken before (PRE), immediately after (POST) and 1 h after exercise for CK, AST, Mb and S100B assessments. We found a significant increase in serum S100B levels and muscle damage markers in RUN POST compared with RUN PRE. Comparing groups, POST S100B, CK, AST and Mb serum levels were higher in RUN than CYC. Only in RUN, the area under the curve (AUC) of serum S100B is positively correlated with AUC of CK and Mb. Therefore, immediately after an intense exercise such as running, but not cycling, serum levels of S100B protein increase in parallel with levels of CK, AST and Mb. Additionally, the positive correlation between S100B and CK and Mb points to S100B as an acute biomarker of muscle damage after running exercise.