Browsing by Author "Barbosa, Tiago M."
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- Aerodynamics of a wheelchair sprinter racing at the 100m world record pace by CFDPublication . Forte, Pedro; Marinho, Daniel A.; Morais, Jorge E.; Morouço, Pedro; Pascoal-Faria, Paula; Barbosa, Tiago M.The aim of this study was to analyze aerodynamics in a racing position of a wheelchair-racing sprinter, at the world record speed. The athlete and wheelchair were scanned at the beginning of the propulsive phase position (hands near the handrims at 12h) for the 3D model acquisition. Numerical simulation was run on Fluent, having as output the pressure, viscosity and total drag force, and respective coefficients of drag at the world record speed in T-52 category. Total drag was 7.56N and coefficient of drag was 1.65. This work helped on getting a deeper insight about the aerodynamic profile of a wheelchair-racing athlete, at a 100m world record speed.
- Anthropometric Measures, Muscle Resistance, and Balance in Physically Active, Aged AdultsPublication . Rodrigues, Filipe; Antunes, Raul; Matos, Rui; Jacinto, Miguel; Monteiro, Diogo; Forte, Pedro; Monteiro, A. M.; Barbosa, Tiago M.Objectives: This study aimed to examine the relationship between age, body mass index, muscle strength, and balance in physically active, aged adults. Methods: Eighty-five participants were recruited for this study, having an average age of 70.31 years (SD = 9.90), ranging from 50 to 92 years. Twenty-six (30.6%) participants were male and fifty-nine (69.4%) were female. The participants had an average body mass index of 27.30 kg/m2 (SD = 3.62), ranging from 20.32 to 38.58 kg/m2. Participants undertook the Timed-Up and Go to test balance, and the chair-stand test to assess lower body strength. Hierarchical regression analyses were conducted. Three models (Model 1, 2, and 3) were tested to assess their relationships with balance: M1—Lower body muscle strength; M2—Lower body muscle strength and body mass index; M3—Lower body muscle strength, body mass index, and age. Results: All hierarchical models displayed significant variance. The third model explained 50.9% of the variance in dynamic balance, [F(3, 81) = 27.94, p < 0.001, R = 0.71, Ra2 = 0.51]. The difference in Ra2 between the first, second, and third models was statistically significant (p < 0.05). Age, body mass index, and lower body muscle strength had significant (p < 0.05) correlations with balance. In terms of the significant impact of each predictor, age had the strongest association with balance (p < 0.05). Conclusions: The results are useful to understand mechanisms or diagnose people at risk of fall.
- Estimation of mechanical power and energy cost in elite wheelchair racing by analytical procedures and numerical simulationsPublication . Forte, Pedro; Marinho, Daniel A.; Morais, Jorge E.; Morouço, Pedro; Barbosa, Tiago M.The aim was to compare the mechanical power and energy cost of an elite wheelchair sprinter in the key-moments of the stroke cycle. The wheelchair-athlete system was 3D scanned and then computational fluid dynamics was used to estimate the drag force. Mechanical power and energy cost were derived from a set of formulae. The effective area in the catch, release and recovery phases were 0.41 m2, 0.33 m2 and 0.24 m2, respectively. Drag increased with speed and varied across the key-moments. The catch required the highest total power (range: 62.76–423.46 W), followed-up by the release (61.50–407.85 W) and the recovery (60.09–363.89 W).
- Intracyclic Variation of Force and Swimming PerformancePublication . Morouço, Pedro; Barbosa, Tiago M.; Arellano, Raúl; Vilas-Boas, João P.In front-crawl swimming, the upper limbs perform alternating movements with the aim of achieving a continuous application of force in the water, leading to lower intracyclic velocity variation (dv). This parameter has been identified as a crucial criterion for swimmers’ evaluation. Purpose: To examine the assessment of intracyclic force variation (dF) and to analyze its relationship with dv and swimming performance. Methods: A total of 22 high-level male swimmers performed a maximaleffort 50-m front-crawl time trial and a 30-s maximal-effort fully tethered swimming test, which were randomly assigned. Instantaneous velocity was obtained by a speedometer and force by a strain-gauge system. Results: Similarity was observed between the tests, with dF attaining much higher magnitudes than dv (P < .001; d = 8.89). There were no differences in stroke rate or in physiological responses between tethered and free swimming, with a high level of agreement for the stroke rate and blood lactate increase. Swimming velocity presented a strong negative linear relationship with dF (r = −.826, P < .001) and a moderate negative nonlinear relationship with dv (r = .734, P < .01). With the addition of the maximum impulse to dF, multiple-regression analysis explained 83% of the free-swimming performance. Conclusions: Assessing dF is a promising approach for evaluating a swimmer’s performance. From the experiments, this new parameter showed that swimmers with higher dF also present higher dv, leading to a decrease in performance.
- The Impact of Multicomponent Exercise Protocols Order on the Maximum Voluntary Contraction of Older WomenPublication . Monteiro, António; Rodrigues, Sandra; Matos, Sérgio; Encarnação, Samuel; Teixeira, José; Barbosa, Tiago M.; Rodrigues, Filipe; Forte, PedroThe aim of this study was to evaluate the impact of exercise order in multicomponent training (MCT) on the maximum voluntary contraction (MVC) of older women. A total of 91 older women, ranging in age from 60 to 85 years, were randomly assigned to either Group A or Group B. Group A performed a warm up followed by aerobic training and resistance training, whereas Group B followed a warm up followed by resistance training and aerobic training. A control group (CG) did not engage in any exercise interventions. Statistical analysis was conducted using one-way ANOVA for between-group comparisons, and ANOVA was used for repeated measures. The results revealed that Group A demonstrated significant increases in MVC for knee extensors (KEs) between M1 and M3 (p < 0.001) and between M2 and M3 (p < 0.001). Similarly, Group A exhibited significant increases in MVC for knee flexors (KFs) between M1 and M3 (p = 0.001) and between M2 and M3 (p < 0.001). Both Group A and Group B demonstrated significant increases in MVC for elbow flexors (EFs) between M1 and M3 (p < 0.001). Furthermore, Group B showed a significant increase in hand grip strength (HGS) between M1 and M3 (p < 0.001). Overall, the findings suggest that initiating MCT with aerobic training followed by resistance training is the most effective approach for improving muscle strength in older women.
- The variations on the aerodynamics of a world-ranked wheelchair sprinter in the key moments of the stroke cycle: A numerical simulation analysisPublication . Forte, Pedro; Marinho, Daniel A.; Morais, Jorge E.; Morouço, Pedro; Barbosa, Tiago M.Biomechanics plays an important role helping Paralympic sprinters to excel, having the aerodynamic drag a significant impact on the athlete’s performance. The aim of this study was to assess the aerodynamics in different key-moments of the stroke cycle by Computa tional Fluid Dynamics. A world-ranked wheelchair sprinter was scanned on the racing wheelchair wearing his competition gear and helmet. The sprinter was scanned in three different positions: (i) catch (hands in the 12h position on the hand-rim); (ii) the release (hands in the 18h position on the hand-rim) and; (iii) recovery phase (hands do not touch the hand rim and are hyperextended backwards). The simulations were performed at 2.0, 3.5, 5.0 and 6.5 m/s. The mean viscous and pressure drag components, total drag force and effec tive area were retrieved after running the numerical simulations. The viscous drag ranged from 3.35 N to 2.94 N, pressure drag from 0.38 N to 5.51 N, total drag force from 0.72 N to 8.45 N and effective area from 0.24 to 0.41 m2. The results pointed out that the sprinter was submitted to less drag in the recovery phase, and higher drag in the catch. These findings suggest the importance of keeping an adequate body alignment to avoid an increase in the drag force.