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Lauer J.,University of Savoy | Figueiredo P.,University of Porto | Figueiredo P.,Higher Education Institute of Maia ISMAI | Vilas-Boas J.P.,University of Porto | And 2 more authors.
Journal of Electromyography and Kinesiology | Year: 2013

Propulsion in swimming is achieved by complex sculling movements with elbow quasi-fixed on the antero-posterior axis to transmit forces from the hand and the forearm to the body. The purpose of this study was to investigate how elbow muscle coactivation was influenced by the front crawl stroke phases. Ten international level male swimmers performed a 200-m front crawl race-pace bout. Sagittal views were digitized frame by frame to determine the stroke phases (aquatic elbow flexion and extension, aerial elbow flexion and extension). Surface electromyograms (EMG) of the right biceps brachii and triceps brachii were recorded and processed using the integrated EMG to calculate a coactivation index (CI) for each phase. A significant effect of the phases on the CI was revealed with highest levels of coactivation during the aquatic elbow flexion and the aerial elbow extension. Swimmers stabilize the elbow joint to overcome drag during the aquatic phase, and act as a brake at the end of the recovery to replace the arm for the next stroke. The CI can provide insight into the magnitude of mechanical constraints supported by a given joint, in particular during a complex movement. © 2013 Elsevier Ltd.

Figueiredo P.,University of Porto | Figueiredo P.,Higher Education Institute of Maia ISMAI | Rouard A.,University of Savoy | Vilas-Boas J.P.,University of Porto | Fernandes R.J.,University of Porto
Applied Physiology, Nutrition and Metabolism | Year: 2013

The aim of this study was to investigate how upper- and lower-limb muscle fatigue evolves in a 200-m front crawl swimming race. Surface electromyography signals were collected from the flexor carpi radialis, biceps brachii, triceps brachii, pectoralis major, upper trapezius, tibialis anterior, biceps femoris, and rectus femoris muscles of 10 international-level swimmers; 4 underwater cameras were used for kinematic analysis. In addition, blood lactate was measured before and after the test using capillary blood samples. Swimming speed and stroke length decreased from the beginning to the end of the effort, whereas stroke frequency increased after an initial decrease to maintain speed. Concomitant with the decrease in speed, blood lactate increased to 11.12 (1.65) mmol·L-1. The changes in stroke parameters were associated with an increase in integrated electromyography (20%-25%) and a decrease in spectral parameters (40%-60%) for all of the upper-limb muscles, indicating the reaching of submaximal fatigue. The fatigue process did not occur regularly during the 8 laps of the 200 m but was specific for each muscle and each subject. Lower-limb muscles did not present signals of fatigue, confirming their lower contribution to swimming propulsion. The test was conducted to individualize the training process to each muscle and each subject.

Marques E.A.,University of Porto | Marques E.A.,Higher Education Institute of Maia ISMAI | Mota J.,University of Porto | Viana J.L.,Higher Education Institute of Maia ISMAI | And 8 more authors.
Archives of Gerontology and Geriatrics | Year: 2013

This study examines the effects of 32 weeks of exercise training on balance, lower-extremity muscle strength, bone mineral density (BMD) and serum levels of bone metabolism and inflammatory markers in older adults. Forty-seven healthy older adults (women. =. 24, men. =. 23; mean age 68.2 years) participated in a exercise intervention (60. min/session) that included resistance exercise training (2 days/week) at 75-80% of maximum plus a multicomponent weight-bearing impact exercise training (1 day/week). Outcome measures included lumbar spine and proximal femoral BMD, dynamic balance, muscle strength, serum levels of bone metabolism markers [osteocalcin (OC), C-terminal telopeptide of Type I collagen (CTX), osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL)] and serum levels of inflammatory markers [high sensitive (hs)-C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ]. Potential confounding variables included body composition, dietary intake (using 4-day diet records), and accelerometer-based physical activity. After 32 weeks, both men and women increased dynamic balance (6.4%), muscle strength (11.0%) and trochanter (0.7%), intertrochanter (0.7%), total hip (0.6%), and lumbar spine BMD (1.7%), while OC, CTX, OPG and RANKL levels remained unchanged. In addition, hs-CRP and IFN-γ levels were decreased, while TNF-α levels were unchanged, and a decrease in IL-6 levels was only observed in men. These findings suggest that our combined impact protocol reduces inflammation and increases BMD, balance, and lower-extremity muscle strength, despite having little effect on bone metabolism markers. This reinforces the role of exercise to counteract the age-related inflammation, and the muscle strength, balance and BMD reduction. © 2013 Elsevier Ireland Ltd.

Silva A.F.,University of Porto | Figueiredo P.,University of Porto | Figueiredo P.,Higher Education Institute of Maia ISMAI | Seifert L.,University of Rouen | And 3 more authors.
Journal of Sports Science and Medicine | Year: 2013

The aim of this study was to characterize the backstroke swimming technique of 11-13 year-old swimmers when performing at very high intensity. A sample of 114 swimmers was divided into four groups regarding maturational and gender effect, who performed 25-m backstroke swimming at 50-m pace. Using two underwater cameras the general biomechanical parameters (speed, stroke rate, stroke length and stroke index), the arm stroke phases and two indexes of arm coordination (Index of Coordination 1, which characterizes the continuity between propulsive phases of each arm and Index of Coordination 2 that evaluates the simultaneity between the beginning of the pull of one arm and of the recovery of the other arm) were measured. Post-pubertal swimmers achieved higher values of speed (1.06 ± 0.14 and 1.18 ± 0.14 m·s-1 for pubertal and 1.13 ± 0.14 and 1.24 ± 0.12 m·s-1 for post-pubertal girl and boy swimmers, respectively), stroke length (1.64 ± 0.26 and 1.68 ± 0.25 m·cycle-1 for pubertal and 1.79 ± 0.22 and 1.75 ± 0.27 m·cycle-1 for postpubertal girls and boys, respectively) and stroke index. Regarding genders, male were faster than female swimmers. Boys also showed a higher stroke rate and stroke index than girls, who achieved higher results in the ratio between stroke length and arm span. As it was expected, no hand lag time was noticed in young swimmers. Although no differences were noticed between genders, the Index of Coordination 1 was in catch-up mode (-9.89 ± 3.16 and -10.16 ± 3.60 % for girls and -9.77 ± 2.93 and -10.39 ± 2.44 % for boys pubertal and post-pubertal, respectively) and the Index of Coordination 2 was in superposition mode (1.86 ± 4.39 and 2.25 ± 2.25 % from girls and 1.72 ± 2.62 and 1.95 ± 2.95 % for boys, pubertal and post-pubertal, respectively). © Journal of Sports Science and Medicine.

Figueiredo P.,University of Porto | Figueiredo P.,Higher Education Institute of Maia ISMAI | Pendergast D.R.,State University of New York at Buffalo | Vilas-Boas J.P.,University of Porto | Fernandes R.J.,University of Porto
BioMed Research International | Year: 2013

This study aimed to determine the relative contribution of selected biomechanical, energetic, coordinative, and muscular factors for the 200 m front crawl and each of its four laps. Ten swimmers performed a 200 m front crawl swim, as well as 50, 100, and 150 m at the 200 m pace. Biomechanical, energetic, coordinative, and muscular factors were assessed during the 200 m swim. Multiple linear regression analysis was used to identify the weight of the factors to the performance. For each lap, the contributions to the 200 m performance were 17.6, 21.1, 18.4, and 7.6% for stroke length, 16.1, 18.7, 32.1, and 3.2% for stroke rate, 11.2, 13.2, 6.8, and 5.7% for intracycle velocity variation in x, 9.7, 7.5, 1.3, and 5.4% for intracycle velocity variation in y, 17.8, 10.5, 2.0, and 6.4% for propelling efficiency, 4.5, 5.8, 10.9, and 23.7% for total energy expenditure, 10.1, 5.1, 8.3, and 23.7% for interarm coordination, 9.0, 6.2, 8.5, and 5.5% for muscular activity amplitude, and 3.9, 11.9, 11.8, and 18.7% for muscular frequency). The relative contribution of the factors was closely related to the task constraints, especially fatigue, as the major changes occurred from the first to the last lap. © 2013 Pedro Figueiredo et al.

Sousa A.,University of Porto | Figueiredo P.,Higher Education Institute of Maia ISMAI | Zamparo P.,University of Verona | Vilas-Boas J.P.,University of Porto | Fernandes R.J.,University of Porto
European Journal of Applied Physiology | Year: 2013

To estimate the anaerobic alactic contribution in a 200 m middle distance swimming trial by means of two different methods based: (1) on the fast component of the VO2 off-kinetics (Anarecovery) and (2) on the kinetics of maximal phosphocreatine splitting in the contracting muscle (Anapcr). Ten elite male swimmers performed a 200 m front crawl trial at maximal velocity during which VO2 was directly measured using a telemetric portable gas analyser; during the recovery period VO2 data were collected until baseline values were reached. No significant differences between the two methods were observed; mean ± SD values were 31.7 ± 2.5 and 32.6 ± 2.8 kJ, for Anapcr and Ana recovery, respectively. Despite the existence of some caveats regarding both methods for estimation of the anaerobic alactic contribution, data reported in this study indicate that both yield similar results and both allow to estimate this contribution in supra-maximal swimming trials. This has important implications on swimming energetics, since the non-inclusion of the anaerobic alactic contribution to total metabolic energy expenditure leads to an underestimation of the energy cost at supra-maximal speeds. © 2013 European Union.

Marques E.A.,University of Porto | Marques E.A.,Higher Education Institute of Maia ISMAI | Pizarro A.N.,University of Porto | Figueiredo P.,Higher Education Institute of Maia ISMAI | And 3 more authors.
Preventive Medicine | Year: 2013

Objective: To analyze how modifiable health-related variables are clustered and associated with children's participation in play, active travel and structured exercise and sport among boys and girls. Methods: Data were collected from 9 middle-schools in Porto (Portugal) area. A total of 636 children in the 6th grade (340 girls and 296 boys) with a mean age of 11.64. years old participated in the study. Cluster analyses were used to identify patterns of lifestyle and healthy/unhealthy behaviors. Multinomial logistic regression analysis was used to estimate associations between cluster allocation, sedentary time and participation in three different physical activity (PA) contexts: play, active travel, and structured exercise/sport. Results: Four distinct clusters were identified based on four lifestyle risk factors. The most disadvantaged cluster was characterized by high body mass index, low high-density lipoprotein cholesterol and cardiorespiratory fitness and a moderate level of moderate to vigorous PA. Everyday outdoor play (OR = 1.85, 95%CI 0.318-0.915) and structured exercise/sport (OR = 1.85, 95%CI 0.291-0.990) were associated with healthier lifestyle patterns. There were no significant associations between health patterns and sedentary time or travel mode. Conclusion: Outdoor play and sport/exercise participation seem more important than active travel from school in influencing children's healthy cluster profiles. © 2013 Elsevier Inc.

Figueiredo P.,University of Porto | Figueiredo P.,Higher Education Institute of Maia ISMAI | Morais P.,University of Porto | Vilas-Boas J.P.,University of Porto | Fernandes R.J.,University of Porto
European Journal of Applied Physiology | Year: 2013

The purpose of the present study was to understand the energetic, biomechanical and coordinative changes occurring throughout the transition of the lactate threshold. Twelve high-level swimmers (six males and six females) performed a paced intermittent incremental protocol of 7 × 200 m (0.05 m s-1 increments and 30 s intervals). The stroking parameters (stroke rate and stroke length) and the index of coordination (IdC) were assessed by analysis of video recordings from aerial and underwater side-view cameras. Energy cost (C) was determined by the ratio energy expenditure/velocity. Energy expenditure was determined by measuring oxygen uptake (VO2)and blood lactate concentrations ([La-]). The swimming velocity at the inflection point of stroke rate, stroke length, IdC, VO2, and [La-] was determined (m s-1). The results showed that stroke rate, stroke length, IdC, VO2, and [La-] all exhibited inflection point as a function of swimming velocity, and these velocities were highly correlated with the velocity at [La-] inflex (1.35 ± 0.07 m s-1; R = 0.99, P < 0.001). Furthermore, these values were not significantly different (P > 0.05), and Bland-Altman plots estimations were almost unbiased. These findings seem to confirm that as swimming velocity increases and lactate threshold is surpassed, it induces changes in stroke mechanics and organization suggesting an important biomechanical, coordinative and metabolic boundary between moderate and heavy intensity domains. © 2013 Springer-Verlag Berlin Heidelberg.

Santos M.P.,University of Porto | Pizarro A.N.,University of Porto | Mota J.,University of Porto | Marques E.A.,University of Porto | Marques E.A.,Higher Education Institute of Maia ISMAI
BMC Public Health | Year: 2013

Background: Parents are likely to be a basic influence on their children's behavior. There is an absence of information about the associations between parents' physical activity and perception of neighborhood environment with children's independent mobility. The purpose of this study is to examine the contribution of parental physical activity and perception of neighborhood safety to children's independent mobility. Methods. In this cross-sectional study of 354 pupils and their parents, independent mobility, perceptions of neighborhood safety and physical activity were evaluated by questionnaire. Categorical principal components analyses were used to determine the underlying dimensions of both independent mobility and perceptions of neighborhood safety items. Results: The strongest predictor of independent mobility was the parental perception of sidewalk and street safety (ß = 0.132). Parent's physical activity was also a significant predictor. The final model accounted for 13.0% of the variance. Conclusions: Parental perception of neighborhood safety and parents' self reported physical activity might be associated with children's independent mobility. Further research in this topic is needed to explore this possible association. © 2013 Santos et al.; licensee BioMed Central Ltd.

Pizarro A.N.,University of Porto | Ribeiro J.C.,University of Porto | Marques E.A.,University of Porto | Marques E.A.,Higher Education Institute of Maia ISMAI | And 2 more authors.
International Journal of Behavioral Nutrition and Physical Activity | Year: 2013

Background: Active commuting to/from school is an important source of physical activity that has been declining over the past years. Although it is an affordable and simple way of increasing physical activity levels it is still unclear whether it has enough potential to improve health. Therefore, the aim of this cross sectional study was to examine the relationship between active commuting to/from school and metabolic risk factors in 10 to 12 year old children.Methods: Participants were 229 adolescents, selected through consecutive sampling, (121 girls) with mean age of 11.65 (±0.73) years old from Porto, Portugal. Means of transport to/from school was accessed by asking: " How do you usually travel to school?" and " How do you usually travel from school?" Active commuting was considered if children reported at least one of the trips (to or from school) by active means. Total physical activity was obtained with Actigraph accelerometer for 7 consecutive days. Lipid profile measurements were conducted with Cholestech LDX® analyser. Waist circumference and blood pressure were measured by standard methods. The criteria for metabolic syndrome defined by International Diabetes Federation for children and adolescents were used.Results: Adjusted binary logistic regression analysis suggested that walkers have higher odds to have a better waist circumference (OR = 2.64, 95% CI = 1.63-6.01) and better high density lipoprotein cholesterol (OR = 2.14, 95% CI = 1.01-4.52) profiles than non-active commuters, independent of moderate-to-vigorous physical activity. No associations were found for other metabolic risk factors.Conclusions: Exertions to increase and maintain walking to school may be particularly relevant as it is likely to have a positive impact on children's health and eventually decrease metabolic and cardiovascular diseases. © 2013 Pizarro et al.; licensee BioMed Central Ltd.

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