Research Center in Sports Sciences, Health Sciences and Human Development

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Publications

Analysis of a normal and aero helmet on an elite cyclist in the dropped position

Publication . Forte, Pedro; Marinho, D.A.; Barbosa, Tiago M.; Morais, J.E.

Cyclists use to wear different helmets and adopt different body positions on the bicycle to minimize resistance. The aim of this study was to compare a standard helmet with the new aero road helmets in a bicycle-cyclist system by CFD on the dropped position. An elite level road cyclist volunteered to this research. The cyclist was scanned on his racing bicycle on the dropped position wearing competition gear and a standard helmet and an aero road helmet. A three-dimensional domain around the cyclist with 7 m of length, 2.5 m of width and 2.5 m of height and meshed with more than 43 million of prismatic and tetrahedral elements. The numerical simulations were conducted at 11.11 m/s. The numerical simulations outputs were viscous, pressure and total drag and coefficient of drag. The standard helmet presented a viscous drag of 10.52 N, a pressure drag of 16.51 N and a total drag of 21.98 N. The aero road helmet presented a pressure drag of 7.40 N, a viscous drag of 12.56 N and a total drag of 19.96 N. Moreover, the aero road helmet presented a lower viscous, pressure and total drag coefficient in comparison to the standard helmet. It is possible to conclude that an aero road helmet imposes less drag in comparison to a standard helmet.

2020Journal article

Open access

Skillful swimming in age-groups is determined by anthropometrics, biomechanics and energetics

Publication . Barbosa, Tiago M.; Bartolomeu, Raúl Filipe; Morais, J.E.; Costa, M.J.

The aim was to compare the anthropometrics, biomechanics and energetics in young swimmers of different competitive levels. Seventy-five boys aged between 11 and 13 years-old with a broad range of performances were ranked based on their personal best time in the men’s 100m freestyle event and then split-up into three tiers (Tier-1, i.e., top-tier, best performers; Tier-2, mid-tier; Tier-3, lower-tier). A set of anthropometric features was measured (height, body mass, arm span and trunk transverse surface area). Stroke kinematics (speed, stroke length, stroke frequency) was assessed by a Speedo-meter. Swim efficiency was then estimated (stroke index, speed fluctuation, Froude efficiency). Hydrodynamics assessment encompassed the estimation of active drag and drag coefficient by velocity perturbation method and a set of dimensionless numbers (Froude, hull speed, Reynolds). Mechanical power (to overcome drag, transfer of kinetic energy to water, external power) and power input were derived. There was a significant variation with moderate effect sizes in all anthropometric features but the trunk transverse surface area. Tier-1 swimmers were taller, heavier and with longer limbs than remaining counterparts. There were also significant variations in the stroke kinematics with moderate-large effect sizes. Tier-1 swimmers showed higher stroke frequency, stroke length, speed, stroke index and propelling efficiency but lower speed fluctuations. Reynold number, Froude number and hull speed were significantly higher in Tier-1 swimmers, denoting large effect sizes. The mechanical power and power input delivered were significantly higher in tier-1 swimmers, showing moderate effect sizes. As a conclusion, it was noted significant variations, with moderate-large effect sizes, among the three tiers, for the vast majority of the selected variables. The better performances by tier-1 swimmers were related to their anthropometrics, biomechanics and energetics.

2019Journal article

Open access

The measurement of thrust in competitive swimming: the association between different thrust variables

Publication . Barbosa, Tiago M.; Yam, Jia Wen; Balasekaran, Govindasamy; Marinho, D.A.

Swimming acceleration and velocity are the net balance between Drag Force and Thrust

2020Conference object

Open access

Through the looking glass: a systematic review of longitudinal evidence, providing new insight for motor competence and health

Publication . Barnett, Lisa M.; Webster, E. Kipling; Hulteen, Ryan M.; Meester, An de; Valentini, Nadia C.; Lenoir, Matthieu; Pesce, Caterina; Getchell, Nancy; Lopes, Vitor P.; Robinson, Leah E.; Brian, Ali; Rodrigues, Luis Paulo

In 2008, a conceptual model explaining the role of motor competence (MC) in children’s physical activity (PA), weight status, perceived MC and health-related fitness was published. Objective: The purpose of the current review was to systematically compile mediation, longitudinal and experimental evidence in support of this conceptual model. Methods: This systematic review (registered with PROSPERO on 28 April 2020) was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. Separate searches were undertaken for each pathway of interest (final search 8 November 2019) using CINAHL Complete, ERIC, Medline (OVID), PsycINFO, Web of Science Core Collection, Scopus and SportDiscus. Potential articles were initially identified through abstract and title checking (N = 585) then screened further and combined into one review (n = 152), with 43 articles identified for extraction. Studies needed to be original and peer reviewed, include typically developing children and adolescents first assessed between 2 and 18 years and objective assessment of gross MC and at least one other variable (i.e., PA, weight status, perceived MC, health-related fitness). PA included sport participation, but sport-specific samples were excluded. Longitudinal or experimental designs and cross-sectional mediated models were sought. Strength of evidence was calculated for each pathway in both directions for each domain (i.e., skill composite, object control and locomotor/coordination/stability) by dividing the proportion of studies indicating a significantly positive pathway in the hypothesised direction by the total associations examined for that pathway. Classifications were no association (0–33%), indeterminate/inconsistent (34–59%), or a positive ‘+’ or negative ‘ − ’ association (≥ 60%). The latter category was classified as strong evidence (i.e., ++or −−) when four or more studies found an association. If the total number of studies in a domain of interest was three or fewer, this was considered insufficient evidence to make a determination. Results: There was strong evidence in both directions for a negative association between MC and weight status. There was strong positive evidence for a pathway from MC to fitness and indeterminate evidence for the reverse. There was indeterminate evidence for a pathway from MC to PA and no evidence for the reverse pathway. There was insufficient evidence for the MC to perceived MC pathway. There was strong positive evidence for the fitness-mediated MC/PA pathway in both directions. There was indeterminate evidence for the perceived MC-mediated pathway from PA to MC and no evidence for the reverse. Conclusion: Bidirectional longitudinal associations of MC with weight status are consistent with the model authored by Stodden et al. (Quest 2008;60(2):290–306, 2008). However, to test the whole model, the field needs robust longitudinal studies across childhood and adolescence that include all variables in the model, have multiple time points and account for potential confounding factors. Furthermore, experimental studies that examine change in MC relative to change in the other constructs are needed.

2021Journal article

Open access

Developmental pathways of cardiorespiratory fitness from 6 to 15 years of age

Publication . Rodrigues, Luis Paulo; Bezerra, Pedro; Lopes, Vitor P.

Most of the information gathered about physical fitness of pediatric populations are cross-sectional, resulting in normative perspectives that account for average values relative to age, but not to a comprehensive understanding of developmental individual trajectories. The aim of this study was to model the longitudinal development of cardiorespiratory fitness of boys and girls from 6 to 15 years of age, using an individual centered approach. Two hundred twenty-nine school children (128 boys; 101 girls) were followed on their 20 meters shuttle run test (20mSRT) results from 6 to 15 years of age. Annual measurements were made during the four years of primary school, and again at grade 9th or 10th. Individual trajectories of 20mSRT development were modeled and grouped according to their similarities of change in three different developmental pathways that were included in subsequent hierarchical nested models for testing each sex developmental model of cardiorespiratory fitness. Final models including the developmental pathways showed better deviance statistics (p<.001). Interindividual slope variances were almost zero, and statistically non-significant (0.05 boys 0.01 girls; p>.50), meaning these models capture well the existing variability, in respect to the rate of change. Individual pathways of change in the performance of 20mSRT test can be detected in childhood and adolescence. Additionally, all individual’s developmental trajectories in 20mSRT can be described using three significantly different slopes. These pathways are indicative of a high, average, or low rate of change in performance over the years and differ from the normative approach.

2020Journal article

Restricted access