Percorrer por autor "Santos, Fernando J."
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- Accuracy of hidden Markov models in identifying alterations in movement patterns during biceps-curl weight-lifting exercisePublication . Peres, André B.; Espada, Mário C.; Santos, Fernando J.; Robalo, Ricardo A. M.; Dias, Amândio A. P.; Muñoz-Jiménez, Jesús; Sancassani, Andrei; Massini, Danilo A.; Pessôa Filho, Dalton M.This paper presents a comparison of mathematical and cinematic motion analysis regarding the accuracy of the detection of alterations in the patterns of positional sequence during biceps-curl lifting exercise. Two different methods, one with and one without metric data from the environment, were used to identify the changes. Ten volunteers performed a standing biceps-curl exercise with additional loads. A smartphone recorded their movements in the sagittal plane, providing information on joints and barbell sequential position changes during each lift attempt. An analysis of variance revealed significant differences in joint position (p < 0.05) among executions with three different loads. Hidden Markov models were trained with data from the bi-dimensional coordinates of the joint positional sequence to identify meaningful alteration with load increment. Tests of agreement tests between the results provided by the models with the environmental measurements, as well as those from image coordinates, were performed. The results demonstrated that it is possible to efficiently detect changes in the patterns of positional sequence with and without the necessity of measurement and/or environmental control, reaching an agreement of 86% between each other, and 100% and 86% for each respective method to the results of ANOVA. The method developed in this study illustrates the viability of smartphone camera use for identifying positional adjustments due to the inability to control limbs in an adequate range of motion with increasing load during a lifting task.
- The effect of pitch size manipulation during small sided-games performed by different age category football players : a pilot studyPublication . Espada, Mário C.; Gamonales, José M.; Verardi, Carlos E.L.; Pessôa Filho, Dalton M.; Ferreira, Cátia C.; Robalo, Ricardo A.M.; Dias, Amândio A.P.; Hernández-Beltrán, Víctor; Santos, Fernando J.This research aimed to analyse the pitch size manipulation effect on internal and external load and to study the age effect on the studied variables in different small-sided games (SSGs) formats. Male U-12 (n = 8), U-15 (n = 8) youth football players, and U-23 (n = 8) professional cohorts participated in the study. Two SSGs formats were analyzed, goalkeeper (GK) + 4 vs. 4 + GK, 3 minutes play in 20 × 30 m and 24 × 36 m, with 3 minutes rest between bouts. The variance analysis Anova two-way was used to analyse two independent factors, pitch size, and age group. The playing area manipulation had an effect under the following variables: distance (p < 0.001), speed 0–6 km/h (p < 0.001), speed 12–18 km/h (p < 0.001), speed 18–21 km/h (p < 0.001), accelerations (Ac.) 1–2 m/s2(p < 0.001), decelerations (Dc.) 2–3 m/s2 (p < 0.001), metabolic power (Pmet) (p < 0.001) and high metabolic load distance (HMLD) (p < 0.001). The age group influenced the distance covered (p < 0.001), speed 0–6 km/h (p < 0.001), speed 6–12 km/h (p < 0.001), speed 12–18 km/h (p < 0.001), speed 21–24 km/h (p = 0.030), Ac. 1–2 m/s2 (p < 0.001), Ac. 1–2 m/s2 (p < 0.001Pmet (p < 0.001), HMLD (p < 0.001) and training impulse (TRIMP)(p < 0.001). Playing area manipulation in football SSGs promotes an increase in external load intensity, namely, larger areas are suitable for larger effects at high speeds (>21 km/h) and TRIMP. A careful and detailed evaluation of training tasks, considering the different age category football players, is important to optimize the planning in football, aiming at improving players’ condition and performance and avoiding health problems and injuries.
- Oxygen uptake kinetics and time limit at maximal aerobic workload in tethered swimmingPublication . Massini, Danilo A.; Espada, Mário C.; Macedo, Anderson G.; Santos, Fernando J.; Castro, Eliane A.; Ferreira, Cátia C.; Robalo, Ricardo A. M.; Dias, Amândio A. P.; Almeida, Tiago A. F.; Pessôa Filho, Dalton M.This study aimed to apply an incremental tethered swimming test (ITT) with workloads (WL) based on individual rates of front crawl mean tethered force (Fmean) for the identification of the upper boundary of heavy exercise (by means of respiratory compensation point, RCP), and therefore to describe oxygen uptake kinetics (VO2k) and time limit (tLim) responses to WL corresponding to peak oxygen uptake (WLVO2peak). Sixteen swimmers of both sexes (17.6 ± 3.8 years old, 175.8 ± 9.2 cm, and 68.5 ± 10.6 kg) performed the ITT until exhaustion, attached to a weight-bearing pulley–rope system for the measurements of gas exchange threshold (GET), RCP, and VO2peak. The WL was increased by 5% from 30 to 70% of Fmean at every minute, with Fmean being measured by a load cell attached to the swimmers during an all-out 30 s front crawl bout. The pulmonary gas exchange was sampled breath by breath, and the mathematical description of VO2k used a first-order exponential with time delay (TD) on the average of two rest-to-work transitions at WLVO2peak. The mean VO2peak approached 50.2 ± 6.2 mL·kg−1·min−1 and GET and RCP attained (respectively) 67.4 ± 7.3% and 87.4 ± 3.4% VO2peak. The average tLim was 329.5 ± 63.6 s for both sexes, and all swimmers attained VO2peak (100.4 ± 3.8%) when considering the primary response of VO2 (A1′ = 91.8 ± 6.7%VO2peak) associated with the VO2 slow component (SC) of 10.7 ± 6.7% of end-exercise VO2, with time constants of 24.4 ± 9.8 s for A1′ and 149.3 ± 29.1 s for SC. Negative correlations were observed for tLim to VO2peak, WLVO2peak, GET, RCP, and EEVO2 (r = −0.55, −0.59, −0.58, −0.53, and −0.50). Thus, the VO2k during tethered swimming at WLVO2peak reproduced the physiological responses corresponding to a severe domain. The findings also demonstrated that tLim was inversely related to aerobic conditioning indexes and to the ability to adjust oxidative metabolism to match target VO2 demand during exercise.