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  • Author: João Ribeiro x
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Kelly de Jesus, Ross Sanders, Karla de Jesus, João Ribeiro, Pedro Figueiredo, João P. Vilas-Boas and Ricardo J. Fernandes

Background:

Coaches are often challenged to optimize swimmers’ technique at different training and competition intensities, but 3-dimensional (3D) analysis has not been conducted for a wide range of training zones.

Purpose:

To analyze front-crawl 3D kinematics and interlimb coordination from low to severe swimming intensities.

Methods:

Ten male swimmers performed a 200-m front crawl at 7 incrementally increasing paces until exhaustion (0.05-m/s increments and 30-s intervals), with images from 2 cycles in each step (at the 25- and 175-m laps) being recorded by 2 surface and 4 underwater video cameras. Metabolic anaerobic threshold (AnT) was also assessed using the lactate-concentration–velocity curve-modeling method.

Results:

Stroke frequency increased, stroke length decreased, hand and foot speed increased, and the index of interlimb coordination increased (within a catch-up mode) from low to severe intensities (P ≤ .05) and within the 200-m steps performed above the AnT (at or closer to the 4th step; P ≤ .05). Concurrently, intracyclic velocity variations and propelling efficiency remained similar between and within swimming intensities (P > .05).

Conclusions:

Swimming intensity has a significant impact on swimmers’ segmental kinematics and interlimb coordination, with modifications being more evident after the point when AnT is reached. As competitive swimming events are conducted at high intensities (in which anaerobic metabolism becomes more prevalent), coaches should implement specific training series that lead swimmers to adapt their technique to the task constraints that exist in nonhomeostatic race conditions.

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Ana F. Silva, Pedro Figueiredo, João Ribeiro, Francisco Alves, João Paulo Vilas-Boas, Ludovic Seifert and Ricardo J. Fernandes

To analyze young swimmers’ performance regarding sex and skill level, 23 boys and 26 girls (15.7 ± 0.8 and 14.5 ± 0.8 years old, respectively) were assessed for anthropometry, flexibility, strength, drag, coordination, and biomechanical variables. During a 50-m maximal front-crawl bout, seven aerial and six underwater Qualisys cameras assessed kinematics, and a load cell was used to measure drag (Tedea, United Kingdom) and tethered swimming force. A multivariate analysis of variance test (p < .05) enabled us to observe differences between skill levels in speed, stroke frequency, stroke index, and intracyclic velocity variations, but most relevant differences were noticed when comparing sexes, particularly for anthropometrics, shoulder flexibility, speed, stroke frequency, stroke length, drag, mechanical power, power per stroke, and maximal and mean force. Considering the included variables, only male swimmers’ performance could be predicted through multiple linear regression, with stroke index, left shoulder flexion, and intracycle velocity variations showing great importance in achieving better results.

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Tiago M. Barbosa, Kelly de Jesus, J. Arturo Abraldes, João Ribeiro, Pedro Figueiredo, João Paulo Vilas-Boas and Ricardo J. Fernandes

Background:

The assessment of energetic and mechanical parameters in swimming often requires the use of an intermittent incremental protocol, whose step lengths are corner stones for the efficiency of the evaluation procedures.

Purpose:

To analyze changes in swimming kinematics and interlimb coordination behavior in 3 variants, with different step lengths, of an intermittent incremental protocol.

Methods:

Twenty-two male swimmers performed n × d i variants of an intermittent and incremental protocol (n ≤ 7; d 1 = 200 m, d 2 = 300 m, and d 3 = 400 m). Swimmers were videotaped in the sagittal plane for 2-dimensional kinematical analysis using a dualmedia setup. Video images were digitized with a motion-capture system. Parameters that were assessed included the stroke kinematics, the segmental and anatomical landmark kinematics, and interlimb coordination. Movement efficiency was also estimated.

Results:

There were no significant variations in any of the selected variables according to the step lengths. A high to very high relationship was observed between step lengths. The bias was much reduced and the 95%CI fairly tight.

Conclusions:

Since there were no meaningful differences between the 3 protocol variants, the 1 with shortest step length (ie, 200 m) should be adopted for logistical reasons.

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João Ribeiro, Luís Teixeira, Rui Lemos, Anderson Santiago Teixeira, Vitor Moreira, Pedro Silva and Fábio Yuzo Nakamura

Purpose:

The current study aimed to compare the effects of plyometric (PT) vs. optimum power load (OPL) training on physical performance of young high-level soccer players.

Methods:

Athletes were randomly divided into PT (horizontal and vertical drills) and OPL (squat+hip thrust exercises at the load of maximum power output) interventions, applied over 7 weeks during the in-season period. Squat (SJ) and countermovement (CMJ) jumps, maximal sprint (10 and 30 m) and change of direction (COD; agility T test) were the pre-and post-training measured performance variables. Magnitude-based inference was used for within-and between-group comparisons.

Results:

OPL training induced moderate improvements in vertical SJ (ES:0.97; 90%CI:0.32-1.61) and CMJ (ES:1.02; 90%CI:0.46-1.57), 30 m sprint speed (ES:1.02; 90%CI:0.09-1.95) and COD performance (ES:0.93; 90%CI:0.50-1.36). After PT training method, vertical SJ (ES:1.08; 90%CI:0.66-1.51) and CMJ (ES:0.62; 90%CI:0.18-1.06) were moderately increased, while small enhancements were noticed for 30 m sprint speed (ES:0.21; 90%CI:-0.02-0.45) and COD performance (ES:0.53; 90%CI:0.24-0.81). The 10 m sprint speed possibly increased after PT intervention (small ES: 0.25; 90%CI:-0.05-0.54), but no substantial change (small ES:0.36; 90%CI:-0.40-1.13) was noticed in OPL. For between-group analyses, the COD ability and 30 m sprint performances were possibly (small ES:0.30; 90%CI:-0.20-0.81; Δ=+1.88%) and likely (moderate ES:0.81; 90%CI:-0.16-1.78; Δ=+2.38%) more improved in the OPL than in the PT intervention, respectively.

Conclusions:

The two different training programs improved physical performance outcomes during the in-season period. However, the combination of vertically-and horizontally-based training exercises (squat+hip thrust) at optimum power zone led to superior gains in COD and 30 m linear sprint performances.

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João Ribeiro, Argyris G. Toubekis, Pedro Figueiredo, Kelly de Jesus, Huub M. Toussaint, Francisco Alves, João P. Vilas-Boas and Ricardo J. Fernandes

Purpose:

To conduct a biophysical analysis of the factors associated with front-crawl performance at moderate and severe swimming intensities, represented by anaerobic-threshold (vAnT) and maximal-oxygen-uptake (vV̇O2max) velocities.

Methods:

Ten high-level swimmers performed 2 intermittent incremental tests of 7 × 200 and 12 × 25 m (through a system of underwater push-off pads) to assess vAnT, and vV̇O2max, and power output. The 1st protocol was videotaped (3D reconstruction) for kinematic analysis to assess stroke frequency (SF), stroke length (SL), propelling efficiency (η P), and index of coordination (IdC). V̇O2 was measured and capillary blood samples (lactate concentrations) were collected, enabling computation of metabolic power. The 2nd protocol allowed calculating mechanical power and performance efficiency from the ratio of mechanical to metabolic power.

Results:

Neither vAnT nor vV̇O2max was explained by SF (0.56 ± 0.06 vs 0.68 ± 0.06 Hz), SL (2.29 ± 0.21 vs 2.06 ± 0.20 m), η P (0.38 ± 0.02 vs 0.36± 0.03), IdC (–12.14 ± 5.24 vs –9.61 ± 5.49), or metabolic-power (1063.00 ± 122.90 vs 1338.18 ± 127.40 W) variability. vV̇O2max was explained by power to overcome drag (r = .77, P ≤ .05) and η P (r = .72, P ≤ .05), in contrast with the nonassociation between these parameters and vAnT; both velocities were well related (r = .62, P ≤ .05).

Conclusions:

The biomechanical parameters, coordination, and metabolic power seemed not to be performance discriminative at either intensity. However, the increase in power to overcome drag, for the less metabolic input, should be the focus of any intervention that aims to improve performance at severe swimming intensity. This is also true for moderate intensities, as vAnT and vV˙O2max are proportional to each other.

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Tiago Peçanha, Marcelle Paula-Ribeiro, Edson Campana-Rezende, Rhenan Bartels, João Carlos Bouzas Marins and Jorge Roberto Perrout de Lima

It has been shown that water intake (WI) improves postexercise parasympathetic recovery after moderateintensity exercise session. However, the potential cardiovascular benefit promoted by WI has not been investigated after high-intensity exercise.

Purpose:

To assess the effects of WI on post high-intensity parasympathetic recovery.

Methods:

Twelve recreationally active young men participated in the study (22 ± 1.4 years, 24.1 ± 1.6 kg.m−2). The experimental protocol consisted of two visits to the laboratory. Each visit consisted in the completion of a 30-min high-intensity [~80% of maximal heart rate (HR)] cycle ergometer aerobic session performing randomly the WI or control (CON, no water consumption) intervention at the end of the exercise. HR and RR intervals (RRi) were continuously recorded by a heart rate monitor before, during and after the exercise. Differences in HR recovery [e.g., absolute heart rate decrement after 1 min of recovery (HRR60s) and time-constant of the first order exponential fitting curve of the HRR (HRRτ)] and in postexercise vagalrelated heart rate variability (HRV) indexes (rMSSD30s, rMSSD, pNN50, SD1 and HF) were calculated and compared for WI and CON.

Results:

A similar HR recovery and an increased postexercise HRV [SD1 = 9.4 ± 5.9 vs. 6.0 ± 3.9 millisecond, HF(ln) = 3.6 ± 1.4 vs. 2.4 ± 1.3 millisecond2, for WI and CON, respectively; p < .05] was observed in WI compared with CON.

Conclusion:

The results suggest that WI accelerates the postexercise parasympathetic reactivation after high-intensity exercise. Such outcome reveals an important cardioprotective effect of WI.

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João Breno Ribeiro-Alvares, Maurício Pinto Dornelles, Carolina Gassen Fritsch, Felipe Xavier de Lima-e-Silva, Thales Menezes Medeiros, Lucas Severo-Silveira, Vanessa Bernardes Marques and Bruno Manfredini Baroni

Context: Hamstring strain injury (HSI) is the most prevalent injury in football (soccer), and a few intrinsic factors have been associated with higher injury rates. Objective: To describe the prevalence of the main intrinsic risk factors for HSI in professional and under-20 football players. Design: Cross-sectional study. Setting: Physiotherapy laboratory, Federal University of Health Sciences of Porto Alegre (Brazil). Participants: A total of 101 football players (52 professional and 49 under-20 players). Intervention: An evidence-based testing protocol for screening HSI risk factors. Main Outcome Measures: Anamnesis, ultrasonography of the hamstrings, passive straight-leg raise test, Functional Movement Screen, and isokinetic dynamometry were performed. Eleven HSI risk factors for each leg were assessed, besides the player’s age as a systemic risk factor. Reports were delivered to the coaching staff. Results: Professionals had greater prevalence of HSI history compared with under-20 players (40% vs 18%). No between-group differences were found for the other screening tests. Altogether, 30% of players had already sustained at least one HSI; 58% had a history of injuries in adjacent regions; 49% had short biceps femoris fascicles; 66% and 21% had poor passive and active flexibility, respectively; 42% and 29% had deficits in functional movements and core stability, respectively; 7% and 26% presented bilateral imbalance for hamstring concentric and eccentric strength, respectively; 87% and 94% obtained low values for hamstring-to-quadriceps conventional and functional ratios, respectively. Two-thirds of players had 3 to 5 risk factors per leg. None of the players was fully free of HSI risk factors. Conclusion: Most football players present multiple risk factors for sustaining an HSI. Hamstring weakness is the most prevalent risk factor, but the teams should also be aware of deficits in flexibility, core stability, functional movements, and hamstring fascicle length.

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J. Paulo Vilas-Boas, Lígia Costa, Ricardo J. Fernandes, João Ribeiro, Pedro Figueiredo, Daniel Marinho, António J. Silva, Abel Rouboa and Leandro Machado

The purpose of the current study was to assess and to compare the hydrodynamics of the first and second gliding positions of the breaststroke underwater stroke used after starts and turns, considering drag force (D), drag coefficient (CD) and cross-sectional area (S). Twelve national-level swimmers were tested (6 males and 6 females, respectively 18.2 ± 4.0 and 17.3 ± 3.0 years old). Hydrodynamic parameters were assessed through inverse dynamics from the velocity to time curve characteristic of the underwater armstroke of the breaststroke technique. The results allow us to conclude that, for the same gliding velocities (1.37 ± 0.124 m/s), D and the swimmers’ S and CD values obtained for the first gliding position are significantly lower than the corresponding values obtained for the second gliding position of the breaststroke underwater stroke (31.67 ± 6.44 N vs. 46.25 ± 7.22 N; 740.42 ± 101.89 cm2 vs. 784.25 ± 99.62 cm2 and 0.458 ± 0.076 vs. 0.664 ± 0.234, respectively). These differences observed for the total sample were not evident for each one of the gender’s subgroups.

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Alex S. Ribeiro, Matheus A. Nascimento, Brad J. Schoenfeld, João Pedro Nunes, Andreo F. Aguiar, Edilaine F. Cavalcante, Analiza M. Silva, Luís B. Sardinha, Steven J. Fleck and Edilson S. Cyrino

The main purpose of this study was to compare the effects of resistance training (RT) performed two versus three times per week on phase angle (a cellular health indicator) in older women. A total of 39 women (69.1 ± 5.5 years) were randomly assigned to perform a RT program two (G2X) or three (G3X) days per week for 12 weeks. The RT was a whole-body program (eight exercises, one set, 10–15 repetitions). Phase angle, resistance, reactance, and total body water were assessed by bioimpedance spectroscopy. Intracellular water, reactance, and phase angle increased significantly in G2X (2.1%, 3.0%, and 5.6%, respectively) and G3X (5.0%, 6.9%, and 10.3%, respectively) from pretraining to posttraining, with no significant difference between groups. Bioimpedance resistance decreased similarly in both groups (G2X = −1.7% vs. G3X = −3.2%). We conclude that a single set RT program with a frequency of 2 days per week may be sufficient to promote an improvement in cellular health in older women.

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João Pedro Nunes, Alex S. Ribeiro, Analiza M. Silva, Brad J. Schoenfeld, Leandro dos Santos, Paolo M. Cunha, Matheus A. Nascimento, Crisieli M. Tomeleri, Hellen C.G. Nabuco, Melissa Antunes, Letícia T. Cyrino and Edilson S. Cyrino

The aim of this study was to analyze the association between muscle quality index (MQI) and phase angle (PhA) after a program of progressive resistance training (RT) in older women. Sixty-six older women with previous RT experience (68.8 ± 4.6 years, 156.6 ± 5.3 cm, 66.0 ± 13.0 kg, and 26.7 ± 4.6 kg/m2) underwent 12 weeks of RT (3 ×/week, eight exercises, and 10–15 repetition maximum). Anthropometry, muscular strength (one-repetition maximum tests), and body composition (dual-energy X-ray absorptiometry and spectral bioimpedance) were measured pre- and posttraining. There were observed significant increases for PhA, MQI, muscular strength, muscle mass, and reactance, whereas no significant changes in body fat and resistance were found. A significant correlation was observed between the RT-induced relative changes in PhA and MQI (r = .620). We conclude that improvements in MQI induced by RT are associated with increases in PhA. Therefore, PhA may be a valid tool to track changes in MQI after 12 weeks of RT in older women.