Gustavo Silva

A 3-year longitudinal analysis of changes in fitness, physical activity, fatness and screen time

Aim:  To analyse whether changes in physical activity index (PAI), screen time (ST: television, computer) and body mass index (BMI) made a contribution to longitudinal changes in fitness of children and adolescents. Additionally, we analysed the interaction between baseline fitness level and changes in fitness.

Criterion-related validity of the 20-m shuttle run test in youths aged 13-19 years

Abstract We assessed the agreement between maximal oxygen consumption ([Vdot]O2max) measured directly when performing the 20-m shuttle run test and estimated [Vdot]O2max from five different equations (i.e. Barnett, equations a and b; Léger; Matsuzaka; and Ruiz) in youths. The 20-m shuttle run test was performed by 26 girls (mean age 14.6 years, s = 1.5; body mass 57.2 kg, s = 8.9; height 1.60 m, s = 0.06) and 22 boys (age 15.0 years, s = 1.6; body mass 63.5 kg, s = 11.5; height 1.70 m, s = 0.01). The participants wore a portable gas analyser (K4b2, Cosmed) to measure [Vdot]O2 during the test. All the equations significantly underestimated directly measured [Vdot]O2max, except Barnetts (b) equation. The mean difference ranged from 1.3 ml · kg−1 · min−1 (Barnett (b)) to 5.5 ml · kg−1 · min−1 (Léger). The standard error of the estimate ranged from 5.3 ml · kg−1 · min−1 (Ruiz) to 6.5 ml · kg−1 · min−1 (Léger), and the percentage error ranged from 21.2% (Ruiz) to 38.3% (Léger). The accuracy of the equations available to estimate [Vdot]O2max from the 20-m shuttle run test is questionable at the individual level. Furthermore, special attention should be paid when comparisons are made between studies (e.g. population-based studies) using different equations. The results of the present study suggest that Barnetts (b) equation provides the closest agreement with directly measured [Vdot]O2max (cardiorespiratory fitness) in youth.

Associations between sports participation, levels of moderate to vigorous physical activity and cardiorespiratory fitness in childrenand adolescents.

Abstract The purpose of this study was to analyse the associations between sports participation, levels of moderate to vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF). The study comprised 310 participants (183 girls and 127 boys) aged 11–18 years. Sports participation was assessed by questionnaire and habitual physical activity (PA) was measured objectively with accelerometers. The 20-m shuttle-run test was used to estimate CRF. Logistic regression analyses were carried out with CRF as the outcome. The odds ratio (OR) for being fit was greater for those who comply with 60 min · day−1 in MVPA (OR = 2.612; 95%confidence interval [CI] = 1.614–4.225) in comparison with those who do not. Participation in competitive sports at club levels increased the chances of being fit (OR = 13.483; 95%CI = 4.560–39.864), independently of MVPA levels. There were positive and significant trends in CRF and objectively measured PA across the levels of engagement in competitive sports (P < 0.05). Concluding, participation in competitive sports at club level is more effective than other organised or non-organised sports to reach healthier levels of CRF and recommend levels of MVPA.

Effect of 8-week exercise-based cardiac rehabilitation on cardiac autonomic function: A randomized controlled trial in myocardial infarction patients

PURPOSE The purpose of this study is to evaluate the effects of an 8-week exercise-based cardiac rehabilitation program on traditional and nonlinear heart rate variability (HRV) indexes, assessing the potential confounding influences of habitual physical activity (PA) and dietary intake. METHODS In this parallel-group trial, 96 patients (56 ± 10 years old) were randomized to the exercise group (EG) or to the control group (CG) 4 weeks after an acute myocardial infarction. Exercise-based cardiac rehabilitation program consisted of aerobic exercise at 70% to 85% of maximal heart rate for 3 sessions per week plus usual care. The CG received only usual care. The baseline and final assessments comprised resting short-term HRV (primary outcome) by a Polar R-R recorder under controlled breathing (12 breaths per minute), habitual PA by accelerometers, and dietary intake by a 4-day food diary. RESULTS Two patients in each group dropped out and were not included in the intention-to-treat analysis. In the remaining 92 patients (EG = 47 and CG = 45), at baseline, only a difference in the proportion of nitrate medication use was significant between groups. After 8 weeks, no significant changes were found between groups on traditional and nonlinear HRV indexes (eg, ln HF, EG from 5.7 ± 1.5 to 5.9 ± 1.3 and CG from 5.5 ± 1.6 to 5.5 ± 1.5), habitual PA, and dietary intake. CONCLUSION Eight weeks of exercise-based cardiac rehabilitation program is an insufficient stimulus to improve cardiac autonomic function in post-myocardial infarction patients under optimal medication and with high levels of traditional and nonlinear HRV indexes at baseline.

Effects of Prolonged Intermittent Exercise on Perceptual-Cognitive Processes.

PURPOSE The visual search behaviors and thought processes underpinning anticipation and how these are influenced by intermittent exercise were examined in high- and low-level soccer players. METHODS High-level (n = 8) and low-level (n = 8) players completed a soccer-specific, intermittent exercise protocol that simulated the demands of a match while responding to filmed sequences of offensive play. HR, blood lactate concentrations, anticipation performance, visual search behaviors, and immediate retrospective verbal reports were assessed. RESULTS High-level players demonstrated superior anticipation compared with low-level counterparts, but both groups showed reduced accuracy across the exercise protocol. Mean HR and blood lactate values increased significantly from the beginning to the end of each half of the match (P < 0.05). Visual search data revealed significant group-test session interactions for the number of locations (P < 0.0001), mean fixation durations (P = 0.003), and number of fixations (P < 0.0001). When compared with low-level participants, high-level players used more fixations of shorter duration to more locations at the beginning of each half; whereas at the end of the exercise protocol, they used fewer fixations of longer duration to a lower number of locations. There was a significant group-type of statement-test session interaction (P = 0.001) for the verbal report data. High-level participants generated a great number of evaluation, prediction (in the beginning of the second half), and deep planning statements (during the first and the last test sessions). In contrast, low-level players used more superficial cognition statements than high-level individuals in both halves. CONCLUSION The intermittent exercise induced changes in perceptual-cognitive processes in both groups, although high-level players exhibited superior anticipation across test sessions accompanied by more effective search behaviors and elaborate thought processes.

Cardiorespiratory fitness associates with metabolic risk independent of central adiposity.

This study sought to analyze the associations between cardiorespiratory fitness (CRF), waist circumference (WC) and metabolic risk in children and adolescents. Participants were 633 subjects (58.7% girls) ages 10-18 years. Metabolic risk score (MRS) was calculated from HDL-cholesterol, triglycerides, fasting glucose and mean arterial pressure. MRS was dichotomized into low and high metabolic risk (HMRS). CRF was defined as the maximal oxygen uptake (VO₂max) estimated from the 20 m Shuttle Run Test. The first quartile of CRF was set as the low fitness group. The fourth quartile of WC was defined as high central adiposity. With adjustments for age, sex and WC, CRF was correlated with MRS (r=-0.095; p<0.05). WC was correlated with MRS (r=0.150; p<0.001) after adjustments for age, sex and CRF. Participants who had low fitness levels, presented higher levels of MRS (p<0.001) compared to those who were fit, even after adjustment for age, sex and WC. In comparison with subjects who were fit with normal central adiposity, an increased odds ratio (OR) for being at HMRS was found for participants who were of low fitness level with high central adiposity (OR=2.934; 95%CI= 1.690-5.092) and for those who were of low fitness with normal central adiposity (OR=2.234; 95%CI=1.116-4.279). Results suggest that CRF relates to MRS independently of central adiposity.

Exercise-based cardiac rehabilitation increases daily physical activity of patients following myocardial infarction: subanalysis of two randomised controlled trials.

OBJECTIVE To assess the effects of an exercise-based cardiac rehabilitation programme on daily physical activity levels of patients following myocardial infarction. DESIGN Subanalysis of two randomised, prospective controlled trials. SETTING Outpatient clinic of a secondary hospital. PARTICIPANTS Fifty consecutive patients randomised to the exercise group {n=25; 23 males; mean age 54 [standard deviation (SD) 9] years} or the control group [n=25; 20 males; mean age 58 (SD 9) years]. INTERVENTIONS The exercise group participated in an 8-week aerobic exercise programme plus usual medical care and follow-up. The control group received usual medical care and follow-up. MAIN OUTCOME MEASURES The primary outcome measure was change in time spent undertaking moderate-to-vigorous physical activity per day, assessed by accelerometer over 7 consecutive days. Secondary outcome measures were cardiorespiratory fitness, body mass, and resting blood pressure and heart rate. RESULTS Moderate-to-vigorous physical activity levels increased significantly in the exercise group [43.2 (SD 36.3) to 53.5 (SD 31.9) minutes/day, P=0.030], and remained unchanged in the control group [40.8 (SD 26.2) to 36.8 (SD 26.5) minutes/day, P=0.241] from baseline to the end of the programme. Cardiorespiratory fitness increased significantly in the exercise group (mean difference 2.8; 95% of the difference 1.3 to 4.4ml/kg/minute, P=0.001) after the 8-week programme. CONCLUSIONS In patients under optimal medication following myocardial infarction, participation in an 8-week exercise-based cardiac rehabilitation programme was found to improve physical activity levels consistent with health-related benefits. Future studies are needed to determine whether the increase in physical activity is maintained in the long term.

Reliability and validity of 6MWT for outpatients with schizophrenia: A preliminary study.

Although the 6-minute walk test (6MWT) has been widely used in patients with schizophrenia, there is a lack of scientific evidence about its reliability and validity in this population. The first goal of this study was to explore the test-retest reliability of the 6MWT and to identify the associated parameters that contribute to the variability of the distance walked during the 6MWT in outpatients with schizophrenia. The second goal was to assess the criterion validity of the 6MWT in men with schizophrenia. Fifty one outpatients with schizophrenia participated in the study. To test-retest reliability (men=39; women=12), participants performed the 6MWT twice within 3 days interval. To test criterion validity (men=13), peak oxygen uptake (VO2peak) was measured on a treadmill. For the associated parameters with the distance walked (n=51), medications use, smoking behavior, body and bone composition, and physical activity levels were analyzed. No significant differences between the means of the two 6MWTs were found. The intraclass correlation coefficient was 0.94 indicating good reliability. 6MWT correlated significantly with VO2peak (r=0.67) indicating criterion validity. Height, body fat mass, smoking behavior and minutes of PA/week were significantly associated with the 6MWT. Results suggest that 6MWT shows good reliability for individuals with schizophrenia and good validity for the small sample of male participants in this study.

Impact of a School-Based Intervention Protocol—ACORDA Project—On Adipokines in an Overweight and Obese Pediatric Population

PURPOSE There are few reliable studies assessing the effect of physical exercise (PE) on adipokines levels at young ages. Our objective was to study the effects of regular PE on plasma adipokines in pediatric overweight and obesity. METHOD 117 overweight and obese children and adolescents (47% females; 10.2 years) participated in an 8-month longitudinal study divided in two groups: PE group (n = 80), engaged in an after-school PE program; control group (n = 37), with no PE program. Plasma lipids, C-reactive protein (CRP), adiponectin, resistin, leptin, IL-6, IL-1beta, TNF-alpha, insulin and glucose levels were determined. RESULTS contrarily to the control group, the PE group presented reductions in body mass index z-score (BMIzsc) and body fat percentage that were accompanied by an improvement in lipid profile and insulin resistance, a reduction in CRP and TNF-alpha and an increase in adiponectin levels. The reductions in BMIzsc were inversely correlated with changes in adiponectin (r=-0.329, p = .003) and positively correlated with changes in percentage body fat (r = .262, p = .032), triglycerides (r = .228, p = .042) and leptin (r = .285, p = .010). CONCLUSIONS Moderate reductions in adiposity improve proinflammatory status in obese children and adolescents. A more substantial reduction in BMIzsc was associated with a greater increment in adiponectin and reduction in leptin.

Quality of life and physical activity levels in outpatients with schizophrenia

Objectives: To assess quality of life (QoL) and physical activity (PA) levels of outpatients with schizophrenia and healthy controls matched for age, gender, body mass index (BMI), hip circumference, waist circumference, and waist-to-hip ratio. Additionally, the present study investigated associations between PA levels, QoL, and anthropometric and behavioral measures among outpatients with schizophrenia. Methods: Thirty-two outpatients with schizophrenia and 32 individuals without mental illness were included in the study. QoL and PA levels were assessed by the World Health Organization Quality of Life Instrument - Abbreviated version (WHOQOL-Bref) and by GT3X triaxial accelerometers, respectively. Results: Outpatients with schizophrenia had poorer QoL and lower vigorous PA levels compared with healthy controls (p < 0.05). The group with schizophrenia showed a significant association between higher weight and lower scores in the mental health domain of the WHOQOL-Bref. A higher BMI was also significantly associated with lower scores in the physical health domain of the WHOQOL-Bref. Schizophrenic patients with smoking behaviors were associated with fewer steps per day and with less moderate to vigorous PA. Conclusions: This study seeks to shed some light upon the lifestyle of patients with schizophrenia. New psychosocial approaches should focus on PA, weight, and smoking management, thereby helping these patients to improve their QoL.