Comparison between protocols for the determination of anaerobic threshold in adolescent swimmers

Aim. The purpose of this study was to compare the anaerobic threshold speed (AT) obtained from fixed lactate blood concentrations (AT 4 mM and AT 3.5 mM), lactate minimum speed (LM) and critical speed (CS), determined from different distances in fifteen Brazilian national level swimmers (10 boys = 14.8 ± 0.6 years old and 5 girls = 14.6 ±0.8 year-old). Methods. The tests to determine the AT 4 mM, AT 3.5 mM, LM and CS were performed in a 25 m swimming pool and consisted of 7 or 8 evaluations separated by 24-48 h intervals. Data were submitted to analysis of variance (ANOVA) for repeated measures, followed by the post hoc Scheffé test and Pearson correlation coefficients. Significance was set at P<0.01. Results. There were no significant differences among the values for AT 4 mM and CS1 (1.34 ± 0.05 vs. 1.33 ± 0.05 m.s -1, respectively). However, AT 4 mM and CS1 were significantly higher than AT 3.5 mM (1.28 ± 0.04 m.s -1), LM (1.27 ± 0.05 m.s -1), CS2 (1.26 ± 0.06 m.s -1), CS3 (1.27 ± 0.06 m.s -1) and CS4 (1.25 ± 0.07 m.s -1). There were no significant differences among the values for AT 3.5 mM, LM, CS2, CS3 and CS4. Conclusion. The results obtained in this study suggest that the anaerobic threshold determined by a fixed lactate concentration of 3.5 mM, as well as the LM and the CS methods determined by different distances, seem to be the most appropriate indexes for the evaluation of aerobic capacity in adolescent swimmers.

Efeito do modelo de periodização com cargas seletivas sobre capacidades motoras durante um mesociclo preparatório em jogadores de futsal

The aim of this study was to verify the effect of selective loads model in professional futsal players, during a preparatory mesocycle. Nine futsal professional players (23±2 anos), from the team of Federation Paulista of soccer indoor championship, composed the sample, characterized by intentional. The players were evaluated in two moments although of a preparatory mesocycle, microcycle 2 (PRE) and microcycle 7 (POS), by the tests of intermittent aerobic fitness, horizontal jump, one leg triple jump, velocity of 15m, agility and anaerobic power. The statistical analysis included the Student-t and Wilxocon tests (P<0.05). The results of horizontal jump, intermittent aerobic fitness and medium power improved, the velocity at 15 m decreased. The select loads model is a good option for the periodization to preparatory mesocycle in futsal.

Physical fitness in children with probable developmental coordination disorder and normal body mass index

Mudanças no índice de massa corporal (IMC), devido a diversos fatores, como o baixo nível de prática de atividade física, são frequentemente associadas ao baixo nível de aptidão física de crianças com provável transtorno do desenvolvimento da coordenação (pTDC). O presente estudo examinou se crianças com pTDC apresentariam desempenhos inferiores em termos de aptidão física quando comparado com seus pares de desenvolvimento típico (DT). Trinta e duas crianças com pTDC e IMC normal e 32 crianças com DT e IMC normal, pareadas por gênero, idade e IMC, realizaram os testes de sentar e alcançar, de salto horizontal, abdominal, puxada na barra 'modificado' e corrida de 9-min. Os resultados mostraram que crianças do grupo pTDC apresentaram menor força explosiva, resistência e força muscular e resistência cardiorrespiratória do que as crianças do grupo TD. Foi concluído que, mesmo com IMC esperado para a idade, crianças com pTDC têm baixo nível de aptidão física.

Correlações entre parâmetros aeróbios e desempenho em esforços intermitentes de alta intensidade

The purpose of the study was to examine the relationships between intermittent high-intensity efforts (RAST) parameters and variables related to aerobic metabolism (anaerobic threshold; LAN, maximal oxygen uptake; VO2MAX and velocity correspondent to VO2MAX; iVO(2MAX)). Eight under-17 (U17) soccer players (16 +/- 1 years) participated in the study. The participants were submitted to a graded exercise test and six maximal sprints of 35m with 10 seconds of passive recovery between each effort (RAST). The RAST parameters were not significant correlated with VO2MAX and LAN. However absolute and relative mean power were significantly correlated with iVO(2MAX) (r=0.79 e r=0.85, respectively). Furthermore, the fatigue index and the relative peak power were significantly correlated with the iVO(2MAX) (r=-0,57 e r=0,73, respectively). In conclusion, the only aerobic variable correlated with performance in consecutive efforts with brief recovery periods, such as RAST, is iVO(2MAX).

Nasal, oral and rectal microbiota of Black lion tamarins (Leontopithecus chrysopygus)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Energy demands in taekwondo athletes during combat simulation

The purpose of this study was to investigate energy system contributions and energy costs in combat situations. The sample consisted of 10 male taekwondo athletes (age: 21 +/- 6 years old; height: 176.2 +/- 5.3 cm; body mass: 67.2 +/- 8.9 kg) who compete at the national or international level. To estimate the energy contributions, and total energy cost of the fights, athletes performed a simulated competition consisting of three 2 min rounds with a 1 min recovery between each round. The combats were filmed to quantify the actual time spent fighting in each round. The contribution of the aerobic (WAER), anaerobic alactic (W-PCR), and anaerobic lactic (Wleft perpendicularLA-right perpendicular) energy systems was estimated through the measurement of oxygen consumption during the activity, the fast component of excess post-exercise oxygen consumption, and the change in blood lactate concentration in each round, respectively. The mean ratio of high intensity actions to moments of low intensity (steps and pauses) was similar to 1:7. The W-AER, W-PCR and (Wleft perpendicularLA-right perpendicular) system contributions were estimated as 120 +/- 22 kJ (66 +/- 6%), 54 +/- 21 kJ (30 +/- 6%), 8.5 kJ (4 +/- 2%), respectively. Thus, training sessions should be directed mainly to the improvement of the anaerobic alactic system (responsible by the highintensity actions), and of the aerobic system (responsible by the recovery process between high- intensity actions).

Effect of continuous and interval exercise training on the PETCO2 response during a graded exercise test in patients with coronary artery disease

OBJECTIVE: The purpose of this study was to evaluate the following: 1) the effects of continuous exercise training and interval exercise training on the end-tidal carbon dioxide pressure (PETCO2) response during a graded exercise test in patients with coronary artery disease; and 2) the effects of exercise training modalities on the association between PETCO2 at the ventilatory anaerobic threshold (VAT) and indicators of ventilatory efficiency and cardiorespiratory fitness in patients with coronary artery disease. METHODS: Thirty-seven patients (59.7 +/- 1.7 years) with coronary artery disease were randomly divided into two groups: continuous exercise training (n = 20) and interval exercise training (n = 17). All patients performed a graded exercise test with respiratory gas analysis before and after three months of the exercise training program to determine the VAT, respiratory compensation point (RCP) and peak oxygen consumption. RESULTS: After the interventions, both groups exhibited increased cardiorespiratory fitness. Indeed, the continuous exercise and interval exercise training groups demonstrated increases in both ventilatory efficiency and PETCO2 values at VAT, RCP, and peak of exercise. Significant associations were observed in both groups: 1) continuous exercise training (PETCO(2)VAT and cardiorespiratory fitness r = 0.49; PETCO(2)VAT and ventilatory efficiency r = -0.80) and 2) interval exercise training (PETCO(2)VAT and cardiorespiratory fitness r = 0.39; PETCO(2)VAT and ventilatory efficiency r = -0.45). CONCLUSIONS: Both exercise training modalities showed similar increases in PETCO2 levels during a graded exercise test in patients with coronary artery disease, which may be associated with an improvement in ventilatory efficiency and cardiorespiratory fitness.

Association between muscle strength and the cardiopulmonary status of individuals living with HIV/AIDS

OBJECTIVE: The purpose of this study was to compare aerobic function [anaerobic threshold (%_VVO2-AT), respiratory compensation point (%_VVO2-RCP) and peak oxygen uptake (_VVO2peak)] between physically active patients with HIV/AIDS and matched controls and to examine associations between disease status, poor muscle strength, depression (as estimated by the profile of mood states questionnaire) and the aerobic performance of patients. METHODS: Progressive treadmill test data for %_VVO2-AT (V-slope method), RCP and (_VVO2peak) were compared between 39 male patients with HIV/AIDS (age 40.6¡1.4 years) and 28 male controls (age 44.4¡2.1 years) drawn from the same community and matched for habitual physical activity. Within-patient data were also examined in relation to CD4+ counts (nadir and current data) and peak isokinetic knee torque. RESULTS: AT, RCP and (_VVO2peak) values were generally similar for patients and controls.Within the patient sample, binary classification suggested that AT, RCP and (_VVO2peak) values were not associated with either the nadir or current CD4+ count, but treadmill test variables were positively associated with peak isokinetic knee torque. CONCLUSION: The aerobic performance of physically active patients with HIV/AIDS is generally well conserved. Nevertheless, poor muscle strength is observed in some HIV/AIDS patients, which is associated with lower anaerobic power and (_VVO2peak), suggesting the possibility of enhancing the aerobic performance of patients with weak muscles through appropriate muscle-strengthening activities.

Sources and pathways of methane formed in oxidative environments

Methane is the most abundant reduced organic compound in the atmosphere. As the strongest known long-lived greenhouse gas after water vapour and carbon dioxide methane perturbs the radiation balance of Earth’s atmosphere. The abiotic formation of methane requires ultraviolet irradiation of organic matter or takes place in locations with high temperature and/or pressure, e.g. during biomass burning or serpentinisation of olivine, under hydrothermal conditions in the oceans deep or below tectonic plates. The biotic methane formation was traditionally thought to be formed only by methanogens under strictly anaerobic conditions, such as in wetland soils, rice paddies and agricultural waste. rnIn this dissertation several chemical pathways are described which lead to the formation of methane under aerobic and ambient conditions. Organic precursor compounds such as ascorbic acid and methionine were shown to release methane in a chemical system including ferrihydrite and hydrogen peroxide in aquatic solution. Moreover, it was shown by using stable carbon isotope labelling experiments that the thio-methyl group of methionine was the carbon precursor for the methane produced. Methionine, a compound that plays an important role in transmethylation processes in plants was also applied to living plants. Stable carbon isotope labelling experiments clearly verified that methionine acts as a precursor compound for the methane from plants. Further experiments in which the electron transport chain was inhibited suggest that the methane generation is located in the mitochondria of the plants. The abiotic formation of methane was shown for several soil samples. Important environmental parameter such as temperature, UV irradiation and moisture were identified to control methane formation. The organic content of the sample as well as water and hydrogen peroxide might also play a major role in the formation of methane from soils. Based on these results a novel scheme was developed that includes both biotic and chemical sources of methane in the pedosphere.rn

REGULATION OF WHOLE-BODY ENERGY HOMEOSTASIS WITH GROWTH HORMONE REPLACEMENT THERAPY AND ENDURANCE EXERCISE

We hypothesized that network analysis is useful to expose coordination between whole body and myocellular levels of energy metabolism and can identify entities that underlie skeletal muscle's contribution to growth hormone-stimulated lipid handling and metabolic fitness. We assessed 112 metabolic parameters characterizing metabolic rate and substrate handling in tibialis anterior muscle and vascular compartment at rest, after a meal and exercise with growth hormone replacement therapy (GH-RT) of hypopituitary patients (n = 11). The topology of linear relationships (| r | ≥ 0.7, P ≤ 0.01) and mutual dependencies exposed the organization of metabolic relationships in three entities reflecting basal and exercise-induced metabolic rate, triglyceride handling, and substrate utilization in the pre- and postprandial state, respectively. GH-RT improved aerobic performance (+5%), lean-to-fat mass (+19%), and muscle area of tibialis anterior (+2%) but did not alter its mitochondrial and capillary content. Concomitantly, connectivity was established between myocellular parameters of mitochondrial lipid metabolism and meal-induced triglyceride handling in serum. This was mediated via the recruitment of transcripts of muscle lipid mobilization (LIPE, FABP3, and FABP4) and fatty acid-sensitive transcription factors (PPARA, PPARG) to the metabolic network. The interdependence of gene regulatory elements of muscle lipid metabolism reflected the norm in healthy subjects (n = 12) and distinguished the regulation of the mitochondrial respiration factor COX1 by GH and endurance exercise. Our observations validate the use of network analysis for systems medicine and highlight the notion that an improved stochiometry between muscle and whole body lipid metabolism, rather than alterations of single bottlenecks, contributes to GH-driven elevations in metabolic fitness.

Host condition and host immunity affect parasite fitness in a bird-ectoparasite system

1. Parasites might preferentially feed on hosts in good nutritional condition as such hosts provide better resources for the parasites' own growth, survival and reproduction. However, hosts in prime condition are also better able to develop costly immunological or physiological defence mechanisms, which in turn reduce the parasites' reproductive success. The interplay between host condition, host defence and parasite fitness will thus play an important part in the dynamics of host-parasite systems.;2. In a 2 x 2 design, we manipulated both the access to food in great tit Parus major broods and the exposure of the nestlings to hen fleas Ceratophyllus gallinae, a common ectoparasite of hole-breeding birds. We subsequently investigated the role of manipulated host condition, host immunocompetence, and experimentally induced host defence in nestlings on the reproductive success of individual hen flea females.;3. The food supplementation of the nestlings significantly influenced the parasites' reproductive success. Female fleas laid significantly more eggs when feeding on food-supplemented hosts.;4. Previous parasite exposure of the birds affected the reproductive success of fleas. However, the impact of this induced host response on flea reproduction depended on the birds' natural level of immunocompetence, assessed by the phytohaemagglutinin (PHA) skin test. Flea fecundity significantly decreased with increasing PHA response of the nestlings in previously parasite-exposed broods. No relationship between flea fitness and host immunocompetence was, however, found in previously unexposed broods. The PHA response thus correlates with the nestlings' ability to mount immunological or physiological defence mechanisms against hen fleas. No significant interaction effect between early flea exposure and food supplementation on the parasites' reproductive success was found.;5. Our study shows that the reproductive success of hen fleas is linked to the hosts' food supply early in life and their ability to mount induced immunological or physiological defence mechanisms. These interactions between host quality and parasite fitness are likely to influence host preference, host choice and parasite virulence and thus the evolutionary dynamics in host-parasite systems.

Physical fitness of industrial firefighters

Firefighting is widely known to be one of the most physically demanding civilian occupations. A subset of this is Industrial Firefighting, which places similarly high physical demands on Industrial Firefighters. Although there are some studies on community firefighters, literature is scant on Industrial Firefighters and their physical fitness. ^ A cross-sectional study of Industrial Firefighters in Petrochemical companies in Texas was carried out in 1996–98 to assess their physical fitness and to develop a set of physical agility criteria useful in their selection and ongoing fitness for duty evaluations. ^ A physical agility criteria and a fitness scorecard was developed based on seven parameters (resting heart rate, diastolic blood pressure, aerobic capacity, muscle strength, muscle endurance, trunk flexibility and total body fat) of musculoskeletal and cardiorespiratory fitness. Each indicator received a minimum of 0 to a maximum of 20 points, based on individual performance. Therefore a minimum and maximum achievable score for the entire battery of tests was 0 and 140 respectively. Of the 111 study subjects, 5 (4.5%) were far above average, 31 (28%) above average, 46 (41.5 %) average, 29 (26%) below average and 0 (0%) far below average as deemed by the physical fitness scorecard. The mean score was 77 (±23) with a minimum and maximum score of 35 and 135 respectively. ^ Following univariate analysis an exploratory factor analysis to group variables and to assess the overall role of constituent variables in total fitness of a firefighter was developed. This was followed by a stepwise linear regression analysis using aerobic capacity as a dependent variable. ^ Finally, a graded implementation strategy was devised, such that all existing Industrial Firefighters would have an opportunity to improve or maintain their physical fitness at or above average level as deemed by the fitness scorecard. ^

Whence a healthy mind: Correlation of physical fitness and academic performance among schoolchildren

Background. Public schools are a key forum in the fight for child health because of the opportunities they present for physical activity and fitness surveillance. However, because schools are evaluated and funded on the basis of standardized academic performance rather than physical activity, empirical research evaluating the connections between fitness and academic performance is needed to justify curriculum allocations to physical activity. ^ Methods. Analyses were based on a convenience sample of 315,092 individually-matched standardized academic (TAKS™) and fitness (FITNESSGRAM®) test records collected by 13 Texas school districts under state mandates. We categorized each fitness result in quintiles by age and gender and used a mixed effects regression model to compare the academic performance of the top and bottom fitness groups for each fitness test and grade level combination. ^ Results. All fitness variables except BMI showed significant, positive associations with academic performance after sociodemographic covariate adjustments, with effect sizes ranging from 0.07 (95% CI: 0.05,0.08) in girls trunklift-TAKS reading to 0.34 (0.32,0.35) in boys cardiovascular-TAKS math. Cardiovascular fitness showed the largest inter-quintile difference in TAKS score (32-75 points), followed by curl-ups. After an additional adjustment for BMI and curl-ups, cardiovascular associations peaked in 8th-9 th grades (maximum inter-quintile difference 142 TAKS points; effect size 0.75 (0.69,0.82) for 8th grade girls math) and showed dose-response characteristics across quintiles (p<0.001 for both genders and outcomes). BMI analysis demonstrated limited, non-linear association with academic performance after adjustment for sociodemographic, cardiovascular fitness and curl-up variables. Low-BMI Hispanic high school boys showed significantly lower TAKS scores than the moderate (but not high) BMI group. High-BMI non-Hispanic white high school girls showed significantly lower scores than the moderate (but not low) BMI group. ^ Conclusions. In this study, fitness was strongly and significantly related to academic performance. Cardiovascular fitness showed a distinct dose-response association with academic performance independent of other sociodemographic and fitness variables. The association peaked in late middle to early high school. The independent association of BMI to academic performance was only found in two sub-groups and was non-linear, with both low and high BMI posing risk relative to moderate BMI but not to each other. In light of our findings, we recommend that policymakers consider PE mandates in middle-high school and require linkage of academic and fitness records to facilitate longitudinal surveillance. School administrators should consider increasing PE time in pursuit of higher academic test scores, and PE practitioners should emphasize cardiovascular fitness over BMI reduction.^

The role of cardiorespiratory fitness and weight status on 24-hr ambulatory blood pressure among adolescents

BACKGROUND: This observational research study investigated the association of cardiorespiratory fitness and weight status with repeated measures of 24-hr ambulatory blood pressure (24-hr ABP). Little is known about these associations and few data exist examining the interaction between cardiorespiratory fitness and weight status and the contributions of each on 24-hr ABP in youth. ^ METHODS: This research study used secondary analysis data from the "Adolescent Blood Pressure and Anger: Ethnic Differences" study. This current study sample included 374 African-American, Anglo-American, and Mexican-American adolescents 11-16 years of age. Mixed-effects models were used for testing the relationship between weight status and cardiorespiratory fitness and repeated measures of ambulatory blood pressure over 24 hours (24-hr ABP). Weight status was categorized into "normal weight" (BMI<85th percentile), "overweight" (85th≤BMI<95th), and "obese" (BMI≥95th). Cardiorespiratory fitness, determined by heart rate recovery (HRR), was defined as the difference between heart rate at peak exercise and heart rate at two minutes post-exercise, as measured by a height-adjusted step test and stratified into two groups: low and high fitness, using a median split. Ambulatory blood pressure (ABP) was monitored for a 24-hr period on a school day using the Spacelabs ambulatory monitor (Model 90207). Blood pressure and heart rate were recorded at 30 minute intervals throughout the day of recording and at 60 minute intervals during sleep. ^ RESULTS: No significant associations were found between weight status and mean 24-hr systolic blood pressure (SBP) or mean arterial pressure (MAP). A significant and inverse association between weight status and mean 24-hr diastolic blood pressure (DBP) was revealed. Cardiorespiratory fitness was significantly and inversely associated with mean 24-hr ABP. High fitness adolescents had significantly lower mean 24-hr SPB, DBP, and MAP measurements than low fitness adolescents. Compared to low fitness adolescents, high fitness adolescents had 1.90 mmHg, 1.16 mmHg, and 1.68 mmHg lower mean 24-hr SBP, DBP, and MAP, respectively. Additionally, high fitness appeared to afford protection from higher mean 24-hr SBP and MAP, irrespective of weight status. Among normal weight adolescents, low fitness resulted in higher mean 24-hr SBP and MAP, compared to their fit counterparts. Among adolescents categorized as high fitness, increasing weight status did not appear to result in higher mean 24-hr SBP or MAP. Cardiorespiratory fitness, rather than weight status, appeared to be a more dominant predictor of mean 24-hr SBP and MAP. ^ CONCLUSIONS: To our knowledge, this research is the first study to investigate the independent and combined contributions of cardiorespiratory fitness and weight status on 24-hr ABP, all objectively measured. The results of this study may potentially guide and inform future research. It appears that early cardiovascular disease (CVD) prevention should focus on improving cardiorespiratory fitness levels among all adolescents, particularly those adolescents least fit, regardless of their weight status, while obesity prevention efforts continue.^