Marcelo Romanzini

Calibration of ActiGraph GT3X, Actical and RT3 accelerometers in adolescents

Abstract The objective of this study was to develop count cut-points for three different accelerometer models: ActiGraph GT3X, RT3 and Actical to accurately classify physical activity intensity levels in adolescents. Seventy-nine adolescents (10–15 years) participated in this study. Accelerometers and oxygen consumption () data were collected at rest and during 11 physical activities of different intensities. Accelerometers were worn on the waist and was measured by a portable metabolic system: Cosmed K4b2. Receiver operating characteristic (ROC) curves were used to determine cut-points. Cut-points for sedentary (SED), moderate-to-vigorous (MVPA) and vigorous-intensity physical activity (VPA) were 46, 607 and 818 counts·15s−1 to the vertical axis of ActiGraph; 180, 757 and 1112 counts·15s−1 to the vector magnitude of ActiGraph; 17, 441 and 873 counts·15s−1 for Actical; and 5.6, 20.4 and 32.2 counts·s−1 for RT3, respectively. For all three accelerometer models, there was an almost perfect discrimination of SED and MVPA (ROC >0.97) and an excellent discrimination of VPA (ROC>0.90) observed. Areas under the ROC curves indicated better discrimination of MVPA by ActiGraph (AUC=0.994) and Actical (AUC=0.993) when compared to RT3 (AUC=0.983). The cut-points developed in this study for the ActiGraph (vector magnitude), RT3 and Actical accelerometer models can be used to monitor physical activity level of adolescents.

Validation of the Brzycki equation for the estimation of 1-RM in the bench press

The aim of the present study was to analyze the validation of the equation proposed by Brzycki for the prediction of a maximum repetition (1-RM) in the bench press. Fifty sedentary or moderately active male subjects (22.2 ± 3.5 years; 64.7 ± 8.6 kg), were initially submitted to six test sessions of 1-RM in the bench press, with 48 hours of interval between each session, in order to determine the maximum workload. A protocol of force resistance was then performed for the determination of 7-10-RM. The used criteria for the validation included: t-Student test for dependent samples, for comparison among the mean values obtained by the predictive equation and by the 1-RM test; Pearson correlation coefficient for analysis of the association degree among the measurements; standard error of estimate (SEE) for evaluation of the mean deviation degree of the individual data along the produced line; total error (TE) for the verification of the mean deviation of the individual values of the identity line; constant error (CE) for analysis of the difference among the mean values obtained in the 1-RM test and predicted by the proposed equation. None statistically significant difference was verified among the values produced by the 1-RM test and the Brzycki equation (P > 0.05). Both the SEE and the TE were relatively low (2.42 kg or 3.4% and 1.55 kg or 2.2%, respectively), as well as the CE found (0.22 kg or 0.3%). Moreover, the correlation coefficient value found was extremely high (r = 0.99; P < 0.05), thus showing a strong association between the values found by the 1-RM test and the Brzycki equation. Therefore, the equation analyzed by this study satisfied the validation criteria established by the literature. The results suggest that the Brzycki equation seems to be a fairly attractive alternative for the estimation of 1-RM values in the bench press from the performance of submaximal tests of 7-10-RM, in sedentary or moderately active male adults.The aim of the present study was to analyze the validation of the equation proposed by Brzycki for the prediction of a maximum repetition (1-RM) in the bench press. Fifty sedentary or moderately active male subjects (22.2 ± 3.5 years; 64.7 ± 8.6 kg), were initially submitted to six test sessions of 1-RM in the bench press, with 48 hours of interval between each session, in order to determine the maximum workload. A protocol of force resistance was then performed for the determination of 7-10-RM. The used criteria for the validation included: t-Student test for dependent samples, for comparison among the mean values obtained by the predictive equation and by the 1-RM test; Pearson correlation coefficient for analysis of the association degree among the measurements; standard error of estimate (SEE) for evaluation of the mean deviation degree of the individual data along the produced line; total error (TE) for the verification of the mean deviation of the individual values of the identity line; constant error (CE) for analysis of the difference among the mean values obtained in the 1-RM test and predicted by the proposed equation. None statistically significant difference was verified among the values produced by the 1-RM test and the Brzycki equation (P > 0.05). Both the SEE and the TE were relatively low (2.42 kg or 3.4% and 1.55 kg or 2.2%, respectively), as well as the CE found (0.22 kg or 0.3%). Moreover, the correlation coefficient value found was extremely high (r = 0.99; P < 0.05), thus showing a strong association between the values found by the 1-RM test and the Brzycki equation. Therefore, the equation analyzed by this study satisfied the validation criteria established by the literature. The results suggest that the Brzycki equation seems to be a fairly attractive alternative for the estimation of 1-RM values in the bench press from the performance of submaximal tests of 7-10-RM, in sedentary or moderately active male adults.

Impact of the use of different skinfold calipers for the analysis of the body composition

With the advances in the studies of body composition, it has been observed that several factors can interfere with the estimates of relative body fat using the skinfold thicknesses method. Therefore, the purpose of this study was to investigate the impact of the use of different skinfold calipers for the analysis of body composition by skinfold thicknesses measurements. Two hundred and fifty nine male subjects (23.3 ± 2.9 years) took part of the study. Nine skinfold thicknesses were measured (abdominal, subscapular, suprailiac, triceps, biceps, midaxillary, chest, medial calf, and thigh) using the Lange (USA) and the Cescorf (Brazil) calipers with accuracy of 1.0 and 0.1 mm, respectively. Significant differences were found in the comparison between the two calipers on all the investigated skinfold thicknesses (1.8 to 31.0%) with highest values obtained by the Lange caliper (p < 0.01). When these values were applied to four different predictive equations, developed by different researchers, the body fat estimate was significantly modified (p < 0.01), resulting in differences of 5.2 to 6.9%. Results indicate that the use of different skinfold calipers may maximize the errors of estimation produced by different predictive equations used for the analysis of body composition.

Validação da equação de Brzycki para a estimativa de 1-RM no exercício supino em banco horizontal

The aim of the present study was to analyze the validation of the equation proposed by Brzycki for the prediction of a maximum repetition (1-RM) in the bench press. Fifty sedentary or moderately active male subjects (22.2 ± 3.5 years; 64.7 ± 8.6 kg), were initially submitted to six test sessions of 1-RM in the bench press, with 48 hours of interval between each session, in order to determine the maximum workload. A protocol of force resistance was then performed for the determination of 7-10-RM. The used criteria for the validation included: t-Student test for dependent samples, for comparison among the mean values obtained by the predictive equation and by the 1-RM test; Pearson correlation coefficient for analysis of the association degree among the measurements; standard error of estimate (SEE) for evaluation of the mean deviation degree of the individual data along the produced line; total error (TE) for the verification of the mean deviation of the individual values of the identity line; constant error (CE) for analysis of the difference among the mean values obtained in the 1-RM test and predicted by the proposed equation. None statistically significant difference was verified among the values produced by the 1-RM test and the Brzycki equation (P > 0.05). Both the SEE and the TE were relatively low (2.42 kg or 3.4% and 1.55 kg or 2.2%, respectively), as well as the CE found (0.22 kg or 0.3%). Moreover, the correlation coefficient value found was extremely high (r = 0.99; P < 0.05), thus showing a strong association between the values found by the 1-RM test and the Brzycki equation. Therefore, the equation analyzed by this study satisfied the validation criteria established by the literature. The results suggest that the Brzycki equation seems to be a fairly attractive alternative for the estimation of 1-RM values in the bench press from the performance of submaximal tests of 7-10-RM, in sedentary or moderately active male adults.The aim of the present study was to analyze the validation of the equation proposed by Brzycki for the prediction of a maximum repetition (1-RM) in the bench press. Fifty sedentary or moderately active male subjects (22.2 ± 3.5 years; 64.7 ± 8.6 kg), were initially submitted to six test sessions of 1-RM in the bench press, with 48 hours of interval between each session, in order to determine the maximum workload. A protocol of force resistance was then performed for the determination of 7-10-RM. The used criteria for the validation included: t-Student test for dependent samples, for comparison among the mean values obtained by the predictive equation and by the 1-RM test; Pearson correlation coefficient for analysis of the association degree among the measurements; standard error of estimate (SEE) for evaluation of the mean deviation degree of the individual data along the produced line; total error (TE) for the verification of the mean deviation of the individual values of the identity line; constant error (CE) for analysis of the difference among the mean values obtained in the 1-RM test and predicted by the proposed equation. None statistically significant difference was verified among the values produced by the 1-RM test and the Brzycki equation (P > 0.05). Both the SEE and the TE were relatively low (2.42 kg or 3.4% and 1.55 kg or 2.2%, respectively), as well as the CE found (0.22 kg or 0.3%). Moreover, the correlation coefficient value found was extremely high (r = 0.99; P < 0.05), thus showing a strong association between the values found by the 1-RM test and the Brzycki equation. Therefore, the equation analyzed by this study satisfied the validation criteria established by the literature. The results suggest that the Brzycki equation seems to be a fairly attractive alternative for the estimation of 1-RM values in the bench press from the performance of submaximal tests of 7-10-RM, in sedentary or moderately active male adults.

Static stretching and performance in multiple sets in the bench press exercise.

Abstract Ribeiro, AS, Romanzini, M, Dias, DF, Ohara, D, da Silva, DRP, Achour, A Jr, Avelar, A, and Cyrino, ES. Static stretching and performance in multiple sets in the bench press exercise. J Strength Cond Res 28(4): 1158–1163, 2014—The purpose of this study was to analyze the acute effect of static stretching on the performance of multiple sets in the bench press (BP) exercise. Fifteen men (26.2 ± 0.7 years, 72.4 ± 1.3 kg, 1.78 ± 0.1 m, 22.8 ± 0.3 kg·m−2) performed 4 sets of the BP exercise at 80% of 1 repetition maximum until concentric failure, both in the stretching condition (SC) and control condition (CC). The rate of force decline between the first and the fourth set was used as fatigue index. A randomized, counterbalanced, crossover design was performed with 48 hours between each session. Two static stretching exercises (pectoral and triceps brachii muscles) were performed in a single set before BP in SC, whereas in CC, subjects remained at rest for 150 seconds. For each stretching exercise, the muscle was held at the maximal stretched position for 30 seconds. No significant difference (p > 0.05) was identified for total repetitions performed in 4 sets (SC, 21.3 ± 0.7% vs. CC, 20.5 ± 0.7%) and in the fatigue index (SC, 75.5 ± 1.3% vs. CC, 73.2 ± 1.9%). The results suggest that the performance of multiple sets in the BP exercise does not seem to be influenced by previous static stretching.

Validity of equations for estimating V[combining dot above]O2peak from the 20-m shuttle run test in adolescents aged 11-13 years.

Abstract Batista, MB, Cyrino, ES, Arruda, M, Dourado, AC, Coelho-E-Silva, MJ, Ohara, D, Romanzini, M, and Ronque, ERV. Validity of equations for estimating V[Combining Dot Above]O2peak from the 20-m shuttle run test in adolescents aged 11–13 years. J Strength Cond Res 27(10): 2774–2781, 2013—The aim of this study was to analyze the validity of 4 regression equations to estimate the peak oxygen consumption (V[Combining Dot Above]O2peak) from the 20-m shuttle run test in adolescents aged 11–13 years. One hundred and fifteen adolescents, 61 boys (mean ± SD: age = 12.3 ± 0.9 years) and 54 girls (age = 12.1 ± 0.7 years) performed the 20-m shuttle run test and an incremental progressive maximal test for direct V[Combining Dot Above]O2peak analysis. Four linear regression equations were used to estimate the V[Combining Dot Above]O2peak: Barnett et al. (equation 1), Léger et al. (equation 2), Mahar et al. (equation 3), and Matsuzaka et al. (equation 4). For boys, only the V[Combining Dot Above]O2peak estimated by EQ3 did not differ from the value directly measured (p > 0.05). The EQ1, EQ2, and EQ4 underestimated the V[Combining Dot Above]O2peak, whereas the EQ3 overestimated, particularly in girls (p < 0.05). Large limits of agreement were found between the reference method and the 4 equations, with higher estimated values by EQ2 for boys (8.36 ± 15.24 mL·kg−1·min−1) and girls (2.45 ± 12.63 mL·kg−1·min−1). The highest correlation values were observed by EQ4 for boys (r = 0.80), EQ1 for girls (r = 0.72), and EQ3 for total sample (r = 0.80). The equations analyzed were not precise for individual V[Combining Dot Above]O2peak prediction; however, the EQ3 revealed better agreement, particularly for boys. Considering the data obtained in the boys and total sample, our results suggest that the EQ3 may provide the best predictive measure of V[Combining Dot Above]O2peak from the 20-m shuttle run test in adolescents aged 11–13 years.

Validação de equações antropométricas para a estimativa da massa muscular por meio de absortometria radiológica de dupla energia em universitários do sexo masculino

Different anthropometric equations have been developed and cross-validated for its use in distinct populations through multicompartimentals models. Dual energy X-ray absorptiometry (DEXA) is a multicompartimental alternative for body composition assessment, however, in Brazil, this model still is not often used, especially for the analysis of the muscle mass (MM). Thus, the purpose of this study was to cross-validate anthropometric equations to estimate relative body fat and MM from DEXA, in young male Brazilian college students. For this, 131 young adults between 18 and 36 years (73,9 ± 9,7 kg; 177,6 ± 6,4 cm; MM = 32,1 ± 3,6 kg) had been evaluated by means of DEXA and anthropometric measures (body mass, stature, circumferences and skinfold thicknesses), been analyzed four equations for the calculation of the MM. The following analysis were applied: descriptive statistics, procedures of cross-validation and analysis of agreement (ICC and Bland and Altman). Equation 3 [MM (kg) = E.(0,00744.CBrC2 + 0,00088.CC x C2 + 0,00441.CPantC2) + 2,4.S - 0,048.Id + R + 7,8] of Lee et al. (Am J Clin Nutr 2000;72:796-803) was validated, for the evaluation of the MM (t = 1,13; r = 0,83; EPE = 2,08; d = 0,21). Beyond this, equation 4, from the same researchers [MM (kg) = 0,244.MC + 7,8.E + 6,6.S - 0,098.Id + R - 3,3] were suggested for its use in the studied sample, in view of the low values presented of EPE (2,20), EC (-0,72), ET (2,72) and d (-0,77) and the good agreements fond (from moderate to high). New cross-validation studies are suggested in different samples, using DEXA as the reference method, as well is suggested a greater utilization of anthropometric equations for the assessment of MM, for the following of MM changes in relation to the growth, development and aging process, and in the evaluation of the physical and sports training.

Effect of Different Warm-up Procedures on the Performance of Resistance Training Exercises:

Warm-up has been shown to mediate numerous acute physiological alterations that have been purported to confer beneficial effects on performance. This study investigated the acute effects of different warm-up procedures on resistance training performance. Employing a randomized, counterbalanced crossover design, 15 men performed 3 exercises (4 sets of bench press, squat, and arm curl at 80% of 1RM) to failure in 4 conditions (control, specific, aerobic, and combined). Outcome measures included the sum of repetitions and a fatigue index measuring the decline between sets. There was no significant difference for the sum of repetitions or for fatigue index among conditions for the 3 exercises. Performance in the resistance training exercises was not influenced by warm-up.

Prevalência e fatores associados à obesidade abdominal em adolescentes

Objective: To determine the prevalence of abdominal obesity in adolescents and its association with demographic, economic and lifestyle variables in adolescents. Methods: This cross-sectional study enrolled 644 adolescents (397 girls and 247 boys) from 15 to 19 years old. Demographic (gender and age), economic (economic status), and lifestyle data (physical activity, diet, smoking, and alcohol consumption) were collected. Abdominal obesity (primary outcome) was evaluated based on the cut-off values for gender- and age-specific waist circumference. Data were analyzed using multivariate logistic regression, estimating the unadjusted and adjusted Odds Ratios (OR) with a 95% confidence interval. Results: The prevalence of abdominal obesity was 7.5%. Boys (OR 2.34; 95%CI 1.27-4.32) of intermediate (OR 2.89; 95%CI 1.35-6.59) and high socioeconomic status (OR 2.98; 95%CI 1.31-6.77) who had an excessive consumption of alcohol (OR 2.12; 95%CI 1.10-4.09) presented the highest chance of abdominal obesity. Conclusions: The prevalence of abdominal obesity was low in the studied population compared to rates reported in international studies. Gender, economic status and excessive alcohol consumption were associated with abdominal obesity.

Prevalence of abdominal obesity and associated factors in adolescents

Objective: To determine the prevalence of abdominal obesity in adolescents and its association with demographic, economic and lifestyle variables in adolescents. Methods: This cross-sectional study enrolled 644 adolescents (397 girls and 247 boys) from 15 to 19 years old. Demographic (gender and age), economic (economic status), and lifestyle data (physical activity, diet, smoking, and alcohol consumption) were collected. Abdominal obesity (primary outcome) was evaluated based on the cut-off values for gender- and age-specific waist circumference. Data were analyzed using multivariate logistic regression, estimating the unadjusted and adjusted Odds Ratios (OR) with a 95% confidence interval. Results: The prevalence of abdominal obesity was 7.5%. Boys (OR 2.34; 95%CI 1.27-4.32) of intermediate (OR 2.89; 95%CI 1.35-6.59) and high socioeconomic status (OR 2.98; 95%CI 1.31-6.77) who had an excessive consumption of alcohol (OR 2.12; 95%CI 1.10-4.09) presented the highest chance of abdominal obesity. Conclusions: The prevalence of abdominal obesity was low in the studied population compared to rates reported in international studies. Gender, economic status and excessive alcohol consumption were associated with abdominal obesity.