J. Paulo Vilas-Boas

Acute Effects of Heavy-Load Exercises, Stretching Exercises, and Heavy-Load Plus Stretching Exercises on Squat Jump and Countermovement Jump Performance

González-Ravé, JM, Machado, L, Navarro-Valdivielso, F, and Vilas-Boas, JP. Acute effects of heavy-load exercises, stretching exercises, and heavy-load plus stretching exercises on squat jump and countermovement jump performance. J Strength Cond Res 23(2): 472-479, 2009-The purpose of this study was to examine the acute effects of heavy-load resistance exercises, static stretching exercises, and heavy-load plus static stretching exercises by untrained subjects, and to determine whether these types of exercise have an effect on the performance of squat jumps (SJs) and countermovement jumps (CMJs). Twenty-four men volunteered to participate in this study and were divided into 3 groups: 1 group performed the strength exercises using heavy loads (3 sets of 4 repetitions at 90% of each subjects 1-repetition maximum (1RM), a second group performed the heavy-load resistance plus stretching exercises (3 sets of 4 repetitions at 90% of each subjects 1RM and 3 stretching exercises for 15 seconds each), and a third group performed the static stretching exercises only (3 stretching exercises for 15 seconds each). No significant differences between the groups were seen in vertical jump height, but there were significant differences (p < 0.004) in the mean jump height between sets within the training session without taking the treatment type (group) into consideration. Significant differences (p < 0.001) were seen in the vertical ground-reaction force in CMJs between sets and training in each group, whereas no differences between groups were seen in SJ; nevertheless, there was a tendency toward significant differences between sets (p < 0.09) without considering the treatment type. The data from this study suggest that strength exercises using heavy loads and heavy-load plus stretching exercises did not have a significant effect on the maximal jump height in untrained subjects. Only stretching exercises showed an increase in SJs and CMJs, but these results were not significantly different from all other scores.

Is time limit at the minimum swimming velocity of VO2 max influenced by stroking parameters

The aim of this study was to observe the relationship between time limit at the minimum velocity that elicits maximal oxygen consumption (TLim-v V̇O2 max) and stroke rate, stroke length, and stroke index. 13 men and 10 women, highly trained swimmers, performed an intermittent incremental test for v V̇O2 max assessment and an all-out swim to estimate TLim-v V̇O2 max. The mean ± SD TLim-v V̇O2 max, v V̇O2 max, stroke rate, stroke length, and stroke index values were 233.36 ± 53.92 sec., 1.40 ± .06 meter/sec., 35.58 ± 2.89 cycles/min., 2.39 ± .22 meter/cycle, and 3.36 ± .41 meter2/(cycle · sec.), respectively. The correlation between TLim-v V̇O2 max and stroke rate was –.51 (p < .01), and values for TLim-v V̇O2 max with stroke length (r = .52, p < .01) and stroke index (r = 45, p < .05). These results seem to suggest that technical skill is a key factor in typical efforts requiring prolonged aerobic power.

The effects of two different swimming training periodization on physiological parameters at various exercise intensities

Abstract This study analysed the effects of two different periodization strategies on physiological parameters at various exercise intensities in competitive swimmers. Seventeen athletes of both sexes were divided to two groups, the traditional periodization (TPG, n = 7) and the reverse periodization group (RPG, n = 10). Each group followed a 10-week training period based on the two different periodization strategies. Before and after training, swimming velocity (SV), energy expenditure (EE), energy cost (EC) and percentage of aerobic (%Aer) and anaerobic (%An) energy contribution to the swimming intensities corresponding to the aerobic threshold (AerT), the anaerobic threshold (AnT) and the velocity at maximal oxygen uptake (vVO2max) were measured. Both groups increased the %An at the AerT and AnT intensity (P ≤ .05). In contrast, at the AnT intensity, EE and EC were only increased in TPG. Complementary, %Aer, %An, EE and EC at vVO2max did not alter in both groups (P > .05); no changes were observed in SV in TPG and RPG at all three intensities. These results indicate that both periodization schemes confer almost analogous adaptations in specific physiological parameters in competitive swimmers. However, given the large difference in the total training volume between the two groups, it is suggested that the implementation of the reverse periodization model is an effective and time-efficient strategy to improve performance mainly for swimming events where the AnT is an important performance indicator.

Kinematic analysis of three water polo front crawl styles

Abstract During water polo matches, players use different front crawl styles. The purpose of this study was to conduct a kinematic analysis of three water polo front crawl styles: front crawl with head under water, front crawl with head above water, and front crawl when leading the ball. Ten proficient water polo players performed 3 × 15 m sprints in each front crawl style, which were recorded three-dimensionally by two surface and four underwater cameras. The results showed no differences in performance and several kinematic characteristics among the water polo front crawl styles. However, front crawl when leading the ball showed shorter stroke length and greater stroke frequency. Front crawl with head underwater presented greater maximal finger depth and elbow angle at mid-stroke position. Front crawl with head above water and when leading the ball showed greater trunk obliquity and maximal depth of right and left foot, and shorter kick stroke frequency. The findings suggest that proficient players learn to master front crawl with head above water to achieve top velocity. Despite the common use of the front crawl with head underwater as the basis for water polo fast displacement, coaches should emphasize the use of the specific water polo styles to attain high performance.

Exercise modality effect on oxygen uptake off‐transient kinetics at maximal oxygen uptake intensity

What is the central question of this study? Do the mechanical differences between swimming, rowing, running and cycling have a potential effect on the oxygen uptake ( V̇O2 ) off‐kinetics after an exercise sustained until exhaustion at 100% of maximal oxygen uptake ( V̇O2max ) intensity? What is the main finding and its importance? The mechanical differences between exercise modes had a potential effect and contributed to distinct amplitude of the fast component (higher in running compared with cycling) and time constant (higher in swimming compared with rowing and cycling) in the V̇O2 off‐kinetic patterns at 100% of V̇O2max intensity. This suggests that swimmers, unlike rowers and cyclists, would benefit more from a longer duration of training intervals after each set of exercise performed at V̇O2max intensity.

Physiological Adaptations to Training in Competitive Swimming: A Systematic Review

Abstract The purpose of this systematic review was to summarize longitudinal studies on swimming physiology and get implications for daily practice. A computerized search of databases according to the PRISMA statement was employed. Studies were screened for eligibility on inclusion criteria: (i) present two testing points; (ii) on swimming physiology; (iii) using adult elite swimmers; (iv) no case-studies or with small sample sizes. Two independent reviewers used a checklist to assess the methodological quality of the studies. Thirty-four studies selected for analysis were gathered into five main categories: blood composition (n=7), endocrine secretion (n=11), muscle biochemistry (n=7), cardiovascular response (n=8) and the energetic profile (n=14). The mean quality index was 10.58 ± 2.19 points demonstrating an almost perfect agreement between reviewers (K = 0.93). It can be concluded that the mixed findings in the literature are due to the diversity of the experimental designs. Micro variables obtained at the cellular or molecular level are sensitive measures and demonstrate overtraining signs and health symptoms. The improvement of macro variables (i.e. main physiological systems) is limited and may depend on the athletes’ training background and experience.

The influence of different soccer cleat type on kinetic, kinematic and neuromuscular ankle variables in artificial turf

Lateral ankle sprain is the most prevalent injury in soccer athletes. Enhanced by the variety of soccer cleats and by increased use of artificial turf, the interaction between the ground and the footwear has taken high importance as a lateral ankle sprain risk factor. The higher incidence of injuries in the second half of the match reflects the need of studying this interaction during tasks involving muscle fatigue. To evaluate the influence of different soccer cleats on kinetic, kinematic and neuromuscular ankle variables in artificial turf under two conditions: with and without fatigue of lateral ankle dynamic stabilizers. Study design: Experimental study within-subjects design. Twenty-four healthy athletes participated in this study. All subjects performed three sets of five medial-lateral unipodal jumps, each one with one of three models of cleats (Turf, Hard and Firm ground) on two conditions: with and without fatigue induced by the isokinetic dynamometer. The electromyographic activity of long and short peroneal heads, ground reaction forces and the movement of the rear-foot were collected and used to calculate kinematic (ankle eversion/inversion, centre of pressure displacement and velocity), kinetic (loading rate of the ground reaction forces) and neuromuscular variables (activation time of peroneal muscles). With the exception of decreased peroneal activation time with the Hard ground model (without fatigue vs. with fatigue), no statistically significant differences were identified in the ankle variables, between cleats, neither between the two evaluated conditions. In healthy soccer athletes, the contributor variables for ankle sprain were not influenced by the kind of soccer cleat in a functional test on a third generation artificial turf.

Anaerobic Threshold Individualized Assessment in a Young Swimmer

The assessment of blood lactate concentrations is considered one essential procedure in physiological diagnosis of swimming performance. Our purpose was to assess the metabolic anaerobic threshold of an 11 year old swimmer through an individualized intermittent incremental protocol. Complementarily, stroking parameters were also determined. The subject performed a front crawl 5 x 200 m test, being the velocity controlled by an acoustic signal. The blood samples were collected from the ear lobe at rest and after each step. Stroke rate was registered by a chronofrequencemeter base 3, and stroke length and velocity were calculated at the end of each 200 m. The individual anaerobic threshold occurred at 1.2 mmol/l, rather lower than the traditionally used 4 mmol/l value suggested for trained swimmers. The velocity corresponding to anaerobic threshold was 1.06 m/s, representing a 5 s difference in a 100 m effort comparing to the velocity of 4 mmol/l. Stroke rate increased and stroke length decreased throughout the incremental protocol, i.e., with the velocity increments. It was concluded that the velocity corresponding to 4 mmol/l does not represent the individual anaerobic threshold in this young trained swimmer, and that he prefer to increase their velocity through the raise of stroke rate. Thus, given the importance of developing swimming technique in age-group swimmers, this swimmer should implement the lengthening of his stroke cycles in the training practice routines, trying to resist to the degradation of the stroke length when velocity increases.

Eccentric flywheel post-activation potentiation influences swimming start performance kinetics

ABSTRACT This study aimed to assess the effects of post-activation potentiation in the strength related variables of a kick start. Thirteen competitive swimmers performed three kick starts after a standardized warm up (denoted USUAL) and another after inducing post-activation through five isotonic repetitions on an eccentric flywheel (denoted PAP). A T-test was used to quantify differences between USUAL and PAP warm up. The best trial of each subject achieved by natural conditions (denoted PEAK) was compared with data obtained after PAP. An instrumented starting block with independent triaxial force plates, collected the strength variables related with the impulse at take off. Improvements in the vertical components of force were observed after PAP compared with USUAL, meanwhile no differences were detected on the horizontal components of it. The velocity at take off was higher after PAP compared with USUAL (4.32 ± 0.88 vs 3.93 ± 0.60 m*s-1; p = 0.02). No differences in force or velocity were detected comparing PAP with PEAK (4.13 ± 0.62 m*s-1, p = 0.11). The PAP warm-up increased vertical force and it was transferred to a higher resultant velocity at take-off. This improvement would equal the best result possible obtained in natural conditions after some trials.

Anaerobic Threshold Individualized Assessment in a Young Swimmer~!2009-07-05~!2009-11-10~!2010-08-13~!

The assessment of blood lactate concentrations is considered one essential procedure in physiological diagnosis of swimming performance. Our purpose was to assess the metabolic anaerobic threshold of an 11 year old swimmer through an individualized intermittent incremental protocol. Complementarily, stroking parameters were also determined. The subject performed a front crawl 5 x 200 m test, being the velocity controlled by an acoustic signal. The blood samples were collected from the ear lobe at rest and after each step. Stroke rate was registered by a chronofrequencemeter base 3, and stroke length and velocity were calculated at the end of each 200 m. The individual anaerobic threshold occurred at 1.2 mmol/l, rather lower than the traditionally used 4 mmol/l value suggested for trained swimmers. The velocity corresponding to anaerobic threshold was 1.06 m/s, representing a 5 s difference in a 100 m effort comparing to the velocity of 4 mmol/l. Stroke rate increased and stroke length decreased throughout the incremental protocol, i.e., with the velocity increments. It was concluded that the velocity corresponding to 4 mmol/l does not represent the individual anaerobic threshold in this young trained swimmer, and that he prefer to increase their velocity through the raise of stroke rate. Thus, given the importance of developing swimming technique in age-group swimmers, this swimmer should implement the lengthening of his stroke cycles in the training practice routines, trying to resist to the degradation of the stroke length when velocity increases.