The purpose of this study was to develop peak ground reaction force (pGRF) and peak loading rate ... more The purpose of this study was to develop peak ground reaction force (pGRF) and peak loading rate (pLR) prediction equations for high-impact activities in adult subjects with a broad range of body masses, from normal weight to severe obesity. A total of 78 participants (27 males; 82.4 ± 20.6 kg) completed a series of trials involving jumps of different types and heights on force plates while wearing accelerometers at the ankle, lower back, and hip. Regression equations were developed to predict pGRF and pLR from accelerometry data. Leave-one-out cross-validation was used to calculate prediction accuracy and Bland–Altman plots. Body mass was a predictor in all models, along with peak acceleration in the pGRF models and peak acceleration rate in the pLR models. The equations to predict pGRF had a coefficient of determination (R2) of at least 0.83, and a mean absolute percentage error (MAPE) below 14.5%, while the R2 for the pLR prediction equations was at least 0.87 and the highest MAP...
The torso muscles play important roles in longitudinal rotation between the upper and lower torso... more The torso muscles play important roles in longitudinal rotation between the upper and lower torso on land but demands on these muscles at different swimming speeds and their role in torso twist in front crawl remains unclear. We aimed to compare torso muscle activity at different front crawl speeds and to assess the relationships between torso muscle activity and torso twist. Three-dimensional kinematics and torso muscle EMG data were collected from 15 male swimmers during middle-distance and sprint front crawl. Internal oblique, external oblique, and rectus abdominis, but not erector spinae, activities were greater at sprint than middle-distance pace. Sprint swimmers are likely to benefit from focusing training on the abdominal muscles. Cross-correlation peak coefficients between muscle activity and torso twist occurred with 517-775 and 400-600 ms lag at middle-distance and sprint paces (respectively). These lags are beyond the torso muscle electromechanical delay (~220 ms) and are too long for these muscles to produce movement changes. Further, peak coefficients coincided with both positive and negative shifts, indicating that muscle activity did not always precede kinematic changes. The torso muscles are therefore likely to play a greater role in maintaining stability and controlling posture in front crawl than producing torso twist.
Patients who undergo bariatric surgery (BS) have an increased risk of falls. Our aim was to deter... more Patients who undergo bariatric surgery (BS) have an increased risk of falls. Our aim was to determine if a multicomponent exercise intervention after BS improves balance. Eighty-four patients with obesity enrolled for BS were recruited and 1 month after BS randomly allocated to a control (CG; standard medical care) or exercise group (EG; exercise plus standard medical care) consisting of a supervised multicomponent training program (3d/week; 75 min/session; 5 months). Anthropometry, lower limb muscle strength (isokinetic dynamometer), vitamin D (ELISA) and balance in bipedal stance (force platform) were assessed pre-BS, 1 month and 6 months post-BS. One month post-BS, significant balance improvements were observed, namely in antero-posterior center of gravity (CoG) displacement and velocity, and medio-lateral and total CoG velocity. Between 1- and 6-months post-BS, improvements in balance were observed only in the EG, with a significant treatment effect on CoG displacement area and ...
FINA recently changed the rule that governs the starting position for the backstroke starting tec... more FINA recently changed the rule that governs the starting position for the backstroke starting technique. With this change, swimmers may now decide to start with the feet emerged, which was previously strictly forbidden. This new liberalization naturally determines the rise of a new technical question for swimmers and coaches: do a starting position with the feet emerged allow a better performance, or better performance conditions for the following actions? To our knowledge no previous scientific results are available concerning this question, allowing to support any technical decision. During this presentation we will try to deliver arguments to support a technical option in this particular topic, based on the research developed by our group, comparing the traditional starting technique with the feet immerged (BSFI), with the one allowed nowadays, with both feet totally, or partially, emerged (BSFE). To fulfil this purpose, we studied six experienced male swimmers that maximally per...
The purpose of this study was to investigate the association between torso muscle activity and to... more The purpose of this study was to investigate the association between torso muscle activity and torso twist. EMG data from five torso muscles and 3D motion capture data were recorded during 4x25m front crawl swimming trials at 400m and 50m pace (N=15). EMG data were integrated over 10ms intervals and normalized to the maximum value during each swimming trial (%iEMG) and torso twist acceleration was calculated as the second time derivative of the relative angle between thorax and pelvis about the longitudinal axis. Spearman correlations were calculated between 5th percentile scores of %iEMG and torso twist acceleration. Mean correlation coefficients were weak (i.e. r < 0.30) for all muscles at both paces. The findings suggest that torso muscle activity may not be directly associated with torso twist acceleration.
ABSTRACTExercise has been suggested as a therapeutic approach to attenuate bone loss induced by b... more ABSTRACTExercise has been suggested as a therapeutic approach to attenuate bone loss induced by bariatric surgery (BS), but its effectiveness remains unclear. Our aim was to determine if an exercise‐training program could induce benefits on bone mass after BS. Eighty‐four patients, submitted to gastric bypass or sleeve gastrectomy, were randomized to either exercise (EG) or control group (CG). One month post‐BS, EG underwent a 11‐month supervised multicomponent exercise program, while CG received only standard medical care. Patients were assessed before BS and at 1, 6, and 12 months post‐BS for body composition, areal bone mineral density (BMD), bone turnover markers, calciotropic hormones, sclerostin, bone material strength index, muscle strength, and daily physical activity. A primary analysis was conducted according to intention‐to‐treat principles and the primary outcome was the between‐group difference on lumbar spine BMD at 12 months post‐BS. A secondary analysis was also perf...
International Journal of Environmental Research and Public Health, 2020
Background: Aquatic physiotherapy has been shown to be effective in developing balance, strength,... more Background: Aquatic physiotherapy has been shown to be effective in developing balance, strength, and functional reach over time. When dealing with immediate effects, the literature has concentrated more on the body’s physiological response to the physical and mechanical properties of water during passive immersion. The purpose of this study was to evaluate the effects of a single 45-min active aquatic physiotherapy session on standing balance and strength, and its relationship with functional reach in persons 55 years and older with upper limb dysfunction. Methods: The intervention group (n = 12) was assessed before and after a single aquatic physiotherapy session, while the control group (n = 10) was evaluated before and after 45 min of sitting rest. Functional assessment was made using the visual analogue pain scale (points), step test (repetitions), functional reach test (cm), and global balance-standing test on a force platform (% time). A two-way repeated-measures ANOVA was ap...
Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 2016
The WalkinSense® is a relatively new device designed to monitor walking exercise. The purpose her... more The WalkinSense® is a relatively new device designed to monitor walking exercise. The purpose here was to assess its reliability and accuracy when analysing spatial–temporal gait parameters. Forty-two young adults performed 3 × 400 m walking at moderate intensity on a 400-m standard track, using both the WalkinSense and a pedometer. The between-trial reliability was excellent for all variables, with intraclass correlation coefficient values ranging from 0.90 to 0.98. The absolute and percentage differences between the WalkinSense and the track length were (mean ± standard deviation) −36.7 ± 45.0 m (95% confidence interval: −44.6, 28.6) and 9.2 ± 11.3% (95% confidence interval: −11.2, 7.2), respectively. The absolute and percentage differences between the WalkinSense and the pedometer for number of strides were 0.7 ± 10.5 strides (95% confidence interval: −1.2, 2.6) and 0.1 ± 4.0% (95% confidence interval: −0.7, 0.8), respectively. The WalkinSense system showed excellent reliability ...
Our purpose was to verify if the use of the new AquaTrainer(®) respiratory snorkel lead to an inc... more Our purpose was to verify if the use of the new AquaTrainer(®) respiratory snorkel lead to an increase of front crawl hydrodynamic drag and whether the constraint of using an adapted turning technique influences its corresponding turning time. 12 swimmers performed 2 (without and with snorkel) 12×25 front crawl repetitions from low to maximal velocity on the measuring active drag system. Complementarily, 3 swimming turns were compared: open turn with snorkel, tumble turn and open turn without snorkel. Drag values were similar without vs. with snorkel at 0.9, 1.1, 1.3, 1.5 and 1.7 m.s(-1) velocities: 15.84 ±5.32 vs. 16.18±4.81, 25.60±6.69 vs. 26.03±6.17, 38.37±8.04 vs. 38.88±7.56, 54.64±10.06 vs. 55.08±9.55, 74.77±14.09 vs. 74.92±13.14 N, (respectively, p≥0.05), and high agreement between conditions was observed (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). Front crawl swimming with snorkel using the open turn implied an increase in turning time of 14.2 and 5.1% than the tumble turn and open turn without the apparatus (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). AquaTrainer(®) snorkel does not lead to an increase in active drag during front crawl performed at a large range of velocities and, consequently, the metabolic energy necessary to overcome total drag will not be affected. However, turning with it requires an additional time that should be taken into account in scientific research and training conditions.
We purposed to study energy expenditure, power output and gross efficiency during kayak ergometer... more We purposed to study energy expenditure, power output and gross efficiency during kayak ergometer exercise in 12 elite sprint kayakers. 6 males (age 24.2±4.8 years, height 180.4±4.8 cm, body mass 79.7±8.5 kg) and 6 females (age 24.3±4.5 years, height 164.5±3.9 cm, body mass 65.4±3.5 kg), performed an incremental intermittent protocol on kayak ergometer with VO2 and blood lactate concentration assessment, a non-linear increase between power output and energy expenditure being observed. Paddling power output, energy expenditure and gross efficiency corresponding to VO2max averaged 199.92±50.41 W, 75.27±6.30 ml.kg - 1.min - 1, and 10.10±1.08%. Male kayakers presented higher VO2max, power output and gross efficiency at the VO2max, and lower heart rate and maximal lactate concentration than females, but no differences were found between genders regarding energy expenditure at VO2max. Aerobic and anaerobic components of energy expenditure evidenced a significant contribution of anaerobic ...
The purpose of this study was to gain more insights about 3D acceleration patterns in kayaks with... more The purpose of this study was to gain more insights about 3D acceleration patterns in kayaks with different numbers of paddlers. Four female international level paddlers participated in this study. A tri-axial accelerometer was positioned on the deck of the ...
The purpose of this study was to develop a system (FPaddle system) to quantify the forces generat... more The purpose of this study was to develop a system (FPaddle system) to quantify the forces generated on each side of the kayak paddle (left and right), in the blades' plane of maximal force application and in other planes, and to gain more insights about the on-...
The purpose of this study was to analyse the intracyclic velocity variation (IVV) of the centre o... more The purpose of this study was to analyse the intracyclic velocity variation (IVV) of the centre of mass (CM) in the x, y, z axes during the stroke cycle event in front crawl, water polo front crawl and water polo front crawl while leading the ball. Ten national level water ...
The purpose of this study was to develop peak ground reaction force (pGRF) and peak loading rate ... more The purpose of this study was to develop peak ground reaction force (pGRF) and peak loading rate (pLR) prediction equations for high-impact activities in adult subjects with a broad range of body masses, from normal weight to severe obesity. A total of 78 participants (27 males; 82.4 ± 20.6 kg) completed a series of trials involving jumps of different types and heights on force plates while wearing accelerometers at the ankle, lower back, and hip. Regression equations were developed to predict pGRF and pLR from accelerometry data. Leave-one-out cross-validation was used to calculate prediction accuracy and Bland–Altman plots. Body mass was a predictor in all models, along with peak acceleration in the pGRF models and peak acceleration rate in the pLR models. The equations to predict pGRF had a coefficient of determination (R2) of at least 0.83, and a mean absolute percentage error (MAPE) below 14.5%, while the R2 for the pLR prediction equations was at least 0.87 and the highest MAP...
The torso muscles play important roles in longitudinal rotation between the upper and lower torso... more The torso muscles play important roles in longitudinal rotation between the upper and lower torso on land but demands on these muscles at different swimming speeds and their role in torso twist in front crawl remains unclear. We aimed to compare torso muscle activity at different front crawl speeds and to assess the relationships between torso muscle activity and torso twist. Three-dimensional kinematics and torso muscle EMG data were collected from 15 male swimmers during middle-distance and sprint front crawl. Internal oblique, external oblique, and rectus abdominis, but not erector spinae, activities were greater at sprint than middle-distance pace. Sprint swimmers are likely to benefit from focusing training on the abdominal muscles. Cross-correlation peak coefficients between muscle activity and torso twist occurred with 517-775 and 400-600 ms lag at middle-distance and sprint paces (respectively). These lags are beyond the torso muscle electromechanical delay (~220 ms) and are too long for these muscles to produce movement changes. Further, peak coefficients coincided with both positive and negative shifts, indicating that muscle activity did not always precede kinematic changes. The torso muscles are therefore likely to play a greater role in maintaining stability and controlling posture in front crawl than producing torso twist.
Patients who undergo bariatric surgery (BS) have an increased risk of falls. Our aim was to deter... more Patients who undergo bariatric surgery (BS) have an increased risk of falls. Our aim was to determine if a multicomponent exercise intervention after BS improves balance. Eighty-four patients with obesity enrolled for BS were recruited and 1 month after BS randomly allocated to a control (CG; standard medical care) or exercise group (EG; exercise plus standard medical care) consisting of a supervised multicomponent training program (3d/week; 75 min/session; 5 months). Anthropometry, lower limb muscle strength (isokinetic dynamometer), vitamin D (ELISA) and balance in bipedal stance (force platform) were assessed pre-BS, 1 month and 6 months post-BS. One month post-BS, significant balance improvements were observed, namely in antero-posterior center of gravity (CoG) displacement and velocity, and medio-lateral and total CoG velocity. Between 1- and 6-months post-BS, improvements in balance were observed only in the EG, with a significant treatment effect on CoG displacement area and ...
FINA recently changed the rule that governs the starting position for the backstroke starting tec... more FINA recently changed the rule that governs the starting position for the backstroke starting technique. With this change, swimmers may now decide to start with the feet emerged, which was previously strictly forbidden. This new liberalization naturally determines the rise of a new technical question for swimmers and coaches: do a starting position with the feet emerged allow a better performance, or better performance conditions for the following actions? To our knowledge no previous scientific results are available concerning this question, allowing to support any technical decision. During this presentation we will try to deliver arguments to support a technical option in this particular topic, based on the research developed by our group, comparing the traditional starting technique with the feet immerged (BSFI), with the one allowed nowadays, with both feet totally, or partially, emerged (BSFE). To fulfil this purpose, we studied six experienced male swimmers that maximally per...
The purpose of this study was to investigate the association between torso muscle activity and to... more The purpose of this study was to investigate the association between torso muscle activity and torso twist. EMG data from five torso muscles and 3D motion capture data were recorded during 4x25m front crawl swimming trials at 400m and 50m pace (N=15). EMG data were integrated over 10ms intervals and normalized to the maximum value during each swimming trial (%iEMG) and torso twist acceleration was calculated as the second time derivative of the relative angle between thorax and pelvis about the longitudinal axis. Spearman correlations were calculated between 5th percentile scores of %iEMG and torso twist acceleration. Mean correlation coefficients were weak (i.e. r < 0.30) for all muscles at both paces. The findings suggest that torso muscle activity may not be directly associated with torso twist acceleration.
ABSTRACTExercise has been suggested as a therapeutic approach to attenuate bone loss induced by b... more ABSTRACTExercise has been suggested as a therapeutic approach to attenuate bone loss induced by bariatric surgery (BS), but its effectiveness remains unclear. Our aim was to determine if an exercise‐training program could induce benefits on bone mass after BS. Eighty‐four patients, submitted to gastric bypass or sleeve gastrectomy, were randomized to either exercise (EG) or control group (CG). One month post‐BS, EG underwent a 11‐month supervised multicomponent exercise program, while CG received only standard medical care. Patients were assessed before BS and at 1, 6, and 12 months post‐BS for body composition, areal bone mineral density (BMD), bone turnover markers, calciotropic hormones, sclerostin, bone material strength index, muscle strength, and daily physical activity. A primary analysis was conducted according to intention‐to‐treat principles and the primary outcome was the between‐group difference on lumbar spine BMD at 12 months post‐BS. A secondary analysis was also perf...
International Journal of Environmental Research and Public Health, 2020
Background: Aquatic physiotherapy has been shown to be effective in developing balance, strength,... more Background: Aquatic physiotherapy has been shown to be effective in developing balance, strength, and functional reach over time. When dealing with immediate effects, the literature has concentrated more on the body’s physiological response to the physical and mechanical properties of water during passive immersion. The purpose of this study was to evaluate the effects of a single 45-min active aquatic physiotherapy session on standing balance and strength, and its relationship with functional reach in persons 55 years and older with upper limb dysfunction. Methods: The intervention group (n = 12) was assessed before and after a single aquatic physiotherapy session, while the control group (n = 10) was evaluated before and after 45 min of sitting rest. Functional assessment was made using the visual analogue pain scale (points), step test (repetitions), functional reach test (cm), and global balance-standing test on a force platform (% time). A two-way repeated-measures ANOVA was ap...
Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 2016
The WalkinSense® is a relatively new device designed to monitor walking exercise. The purpose her... more The WalkinSense® is a relatively new device designed to monitor walking exercise. The purpose here was to assess its reliability and accuracy when analysing spatial–temporal gait parameters. Forty-two young adults performed 3 × 400 m walking at moderate intensity on a 400-m standard track, using both the WalkinSense and a pedometer. The between-trial reliability was excellent for all variables, with intraclass correlation coefficient values ranging from 0.90 to 0.98. The absolute and percentage differences between the WalkinSense and the track length were (mean ± standard deviation) −36.7 ± 45.0 m (95% confidence interval: −44.6, 28.6) and 9.2 ± 11.3% (95% confidence interval: −11.2, 7.2), respectively. The absolute and percentage differences between the WalkinSense and the pedometer for number of strides were 0.7 ± 10.5 strides (95% confidence interval: −1.2, 2.6) and 0.1 ± 4.0% (95% confidence interval: −0.7, 0.8), respectively. The WalkinSense system showed excellent reliability ...
Our purpose was to verify if the use of the new AquaTrainer(®) respiratory snorkel lead to an inc... more Our purpose was to verify if the use of the new AquaTrainer(®) respiratory snorkel lead to an increase of front crawl hydrodynamic drag and whether the constraint of using an adapted turning technique influences its corresponding turning time. 12 swimmers performed 2 (without and with snorkel) 12×25 front crawl repetitions from low to maximal velocity on the measuring active drag system. Complementarily, 3 swimming turns were compared: open turn with snorkel, tumble turn and open turn without snorkel. Drag values were similar without vs. with snorkel at 0.9, 1.1, 1.3, 1.5 and 1.7 m.s(-1) velocities: 15.84 ±5.32 vs. 16.18±4.81, 25.60±6.69 vs. 26.03±6.17, 38.37±8.04 vs. 38.88±7.56, 54.64±10.06 vs. 55.08±9.55, 74.77±14.09 vs. 74.92±13.14 N, (respectively, p≥0.05), and high agreement between conditions was observed (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). Front crawl swimming with snorkel using the open turn implied an increase in turning time of 14.2 and 5.1% than the tumble turn and open turn without the apparatus (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). AquaTrainer(®) snorkel does not lead to an increase in active drag during front crawl performed at a large range of velocities and, consequently, the metabolic energy necessary to overcome total drag will not be affected. However, turning with it requires an additional time that should be taken into account in scientific research and training conditions.
We purposed to study energy expenditure, power output and gross efficiency during kayak ergometer... more We purposed to study energy expenditure, power output and gross efficiency during kayak ergometer exercise in 12 elite sprint kayakers. 6 males (age 24.2±4.8 years, height 180.4±4.8 cm, body mass 79.7±8.5 kg) and 6 females (age 24.3±4.5 years, height 164.5±3.9 cm, body mass 65.4±3.5 kg), performed an incremental intermittent protocol on kayak ergometer with VO2 and blood lactate concentration assessment, a non-linear increase between power output and energy expenditure being observed. Paddling power output, energy expenditure and gross efficiency corresponding to VO2max averaged 199.92±50.41 W, 75.27±6.30 ml.kg - 1.min - 1, and 10.10±1.08%. Male kayakers presented higher VO2max, power output and gross efficiency at the VO2max, and lower heart rate and maximal lactate concentration than females, but no differences were found between genders regarding energy expenditure at VO2max. Aerobic and anaerobic components of energy expenditure evidenced a significant contribution of anaerobic ...
The purpose of this study was to gain more insights about 3D acceleration patterns in kayaks with... more The purpose of this study was to gain more insights about 3D acceleration patterns in kayaks with different numbers of paddlers. Four female international level paddlers participated in this study. A tri-axial accelerometer was positioned on the deck of the ...
The purpose of this study was to develop a system (FPaddle system) to quantify the forces generat... more The purpose of this study was to develop a system (FPaddle system) to quantify the forces generated on each side of the kayak paddle (left and right), in the blades' plane of maximal force application and in other planes, and to gain more insights about the on-...
The purpose of this study was to analyse the intracyclic velocity variation (IVV) of the centre o... more The purpose of this study was to analyse the intracyclic velocity variation (IVV) of the centre of mass (CM) in the x, y, z axes during the stroke cycle event in front crawl, water polo front crawl and water polo front crawl while leading the ball. Ten national level water ...
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Papers by João Vilas-boas