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 Halson et al. (2006). International Journal of Sports Physiology and Performance, 1, 65-9.
HEART RATE VARIABILITY AND VO2 MAX, DURING A ROWING TRAINING SEASON: IMPLICATIONS FOR MONITORING
TRAINING ADAPTATION.RAMA, L., TEIXEIRA, A., SANTOS, A., GOMES, B., MASSARD, A., ROSADO, F., ALVES, F.
FACULTY OF SPORT SCIENCES AND PHYSICAL EDUCATION OF COIMBRAObjectives In Sport Science it is generally accepted that aerobic training promotes higher Heart Rate Variability (HRV) and that intense training leads to lower HRV. The aim of this study was to analyze the utility of heart rate variability as a marker of training adaptation during a rowing training season and it’s sensibility to training load variation.
Methods: 9 males of the national rowing team (22,2 ±2,0 years, 181,2±7,2cm height, 77,9±8,1Kg mass) were selected for this study. HRV time domain (SDRR) and frequency domain (LF, HF absolute, relative and normalized units as was the LF/HF) were measured at rest before a graded test conducted on a Concept II rower ergometer. VO2max, was evaluated and 4 time points controlled according to a year training plan. The first evaluation (t1) took place in the begging of the training season after a transitory period during which the athletes had been released for 5/6 weeks from their normal training. This allowed us to find out the basal values at the beginning of preparation for the sport season. The second evaluation (t2) was done after the first 14 weeks of training with great aerobic predominance and a gradual increment of training volume. The third evaluation (t3) took place at the 28th week, after a phase of intensity increment and a small decrease on training volume. The final evaluation (t4) coincided with a training phase with the highest mean weekly volume and intensity during the season and before a taper period. In this study we adopted a single group repeated measures design in which athletes served as their own control subjects. All ethical presuppositions that a study of this scope compels have been verified.
Results: During the season, VO2max values were: t1=61,49 ± 6,21 ml.kg.min-1; t2=65,37 7,9621 ml.kg.min-1; t3=66,72 6,8021 ml.kg.min-1 and t4 =64,82 8,3021 ml.kg.min-1.
The VO2 at t3 was significantly higher (p0,05) than that observed at t1 and t4. Nevertheless the power at VO2max was from t1 to t4 respectively 334 34, 378 40, 377 52 and 387 45 Watts, higher at all moments when compared to t1 (p0,05). Concerning HRV, we found SDRR higher at t3 (p0,05) and lower at t4, and lower absolute HF(nu) and higher LF (nu) at t3 when compared to the initial values at t1. In summary, during the season at t3, when metabolic values of VO2max were higher, we also found the highest SDRR as marker of global variability, and the lowest LF and highest HF, which indicates a parasympathetic drive on autonomic control of the heart. Also the LF/HF shows a progressive increase during the season, although never attaining a significant variation.
Conclusions Our results agree with those (1) who found a relationship between aerobic capacity development and the predominance of the parasympathetic on the sympatho-vagal balance, and confirmed the utility of at rest HRV control in monitor training adaptation on rowers during a training season.
References Iellamo, F. et al. (2002) Circulation, 105(23), 2719-2724
DOES ELECTRICAL STIMULATION OF KNEE EXTENSOR AND FLEXOR MUSCLES INDUCE DOMS?VANDERTHOMMEN, M., TRIFFAUX, M., DEMOULIN, C., CRIELAARD, J.M., CROISIER, J.L.
UNIVERSITY OF LIEGEIntroduction: Neuromuscular electrical stimulations (NMES) are frequently used to improve muscle performance. It has been shown that the gains observed at the end of a NMES program depend on the intensity of the contractions that are electrically evoked during the training sessions. Therefore, it is suggested to prompt subjects to tolerate the highest current intensity as possible. The present work aimed to study the effect of an intense NMES session on muscle soreness and tightness.
Methods Ten physically active men (24 ± 3 years, 181 ± 4 cm, 74 ± 11 Kg) underwent unilaterally, isometrically and consecutively 20 min of quadriceps (Q) and 20 min of hamstrings (H) NMES. The stimulator provided biphasic rectangular pulses (80 Hz, duration 0.35 ms, on-off ratio 6s) and the current intensity was continually increased throughout the session at maximal tolerable level (~ 75 mA at the end of both bouts). Torque measurements were performed using an isokinetic dynamometer (Biodex3). Subjective perception of muscle soreness was evaluated by the Visual Analogue Scale (0-10 a.u.). Flexibility of the Q was tested with the prone quadriceps flexibility test (distance between heel and buttock with the knee maximally flexed) and the H flexibility was tested with the straight leg raising test (hip angle).
Creatine kinase (CK) activity was measured from blood sampling. All parameters were evaluated before as well as 24 h (d1) and 48 h (d2) after the NMES provocation bout.
Results: During the NMES bout, the stimulated contractions reached, in mean, 31% and 19% of maximal voluntary torque (MVT) for the Q and the H, respectively. All measured variables were significantly modified after the electrostimulated exercise. The highest variations occurred at d2 (mean VAS scores = 3.15 ± 1.83 a.u.; mean reductions in Q flexibility = +3.2 cm; mean reductions in H flexibility = –13°;
mean CK activity = 3021 ± 2693 IU/l).
Discussion: Generally, DOMS occur in skeletal muscle after strenuous exercise, especially when high peak forces are involved during eccentric contractions (Croisier et al., 2003). In the present study, we showed that one session including NMES of quadriceps and hamstrings muscles, realized isometrically and inducing sub-maximal contractions (~ 20-30% MVT), provokes muscle soreness and stiffness and increased CK activities suggesting the occurrence of DOMS. Those DOMS could be induced by the specificities of NMES i.e. temporal and spatial recruitment (Vanderthommen and Duchateau, 2007). The fact that a NMES session, realized in conditions close to the field conditions of training or rehabilitation in terms of stimulation parameters, electrodes positioning and intensity adjustment, can induce an alteration in muscle function constitutes a relevant information.
References Croisier JL, Camus G, Forthomme B, Maquet D, Vanderthommen M and Crielaard JM. (2003). Isokinetics Exerc Sci, 11, 21-29.
Vanderthommen M, Duchateau J. (2007). Exerc Sport Sci Rev, 35, 180-185.
PROFILING ANTHROPOMETRIC AND ISOKINETIC STRENGTH CHARACTERISTICS IN 14-15 YEARS OLD BASKETBALLPLAYERS.
CARVALHO, H.M., MACHADO RODRIGUES, A., FIGUEIREDO, A.F., GONÇALVES, C.E., GONÇALVES, R.S., PHILIPPAERTS, R., COELHO E SILVA, M.J.
UNIVERSITY OF COIMBRAExplosive muscle strength and muscular balance of the knee joint are important parameters to succeed in basketball. Isokinetic testing has been consistently used for assessment of concentric and eccentric strength of the knee joint musculature. The literature is more abundant for soccer players (Sangnier & Tourny-Chollet, J Strength Cond Res, 22: 2008) than for other team sports, in general, and basketball, in particular. In addition, isokinetic assessment has not been systematically considered in adolescent basketball players taking into account growth characteristics. The present study examines the isokinetic parameters of the knee joint musculature in 14-to 15-yearold basketball players by playing position.
A total of 51 basketball players (14.0-15.9 yrs; 2-11 years of training) were categorized as guards (n=16), forwards (n=21), and centers (n=14). Anthropometry included those measurements needed for estimation of leg volumes (Jones & Pearson, J Physiol, 204: 1969), plus stature and body mass. After a 5-min warm-up at 60 rpm in a cycle-ergometer (Monark) and stretching, subjects performed five maximum knee extensions (KE) and flexions (KF) in the isokinetic dynamometer (Biodex system 3, Biodex Corporation, Shirley NY, USA) programmed at 60 degrees/s (modes CON and ECC in both legs. Moments were corrected for the effect of gravity and the highest moment from the five trials for each contraction mode was retained for analysis. Parameters for analysis were absolute peak torque (PT), relative peak torque (PT per kg of body mass), ’functional’ and ’conventional’ hamstrings to quadriceps (H/Q) ratios and bilateral differences (Aagaard et al, Am J Sports Med, 26: 1998). Analysis of variance (ANOVA) was used to test position-related variation in body size and strength parameters. Significance level was set at p≤0.05.
As expected, centers were taller (F=12.251; p 0.01) and heavier (F=11.021; p 0.01) than guards and forwards, whereas forwards had similar stature and body mass as guards in this age group. Results in PT showed differences, from centers to both forwards and guards, in mean ECCKF in the dominant leg (F=3.979; p0.05). Also in the non-dominant leg differences revealed in mean ECCKF (F=4.203;
p0.05) and ECCKE (F=4.392; p0.05). No differences were found in mean CON PT, as well as H/Q ratios and bilateral differences.
The present studies showed a significant position-related variation of body size and absolute peak torque. When expressing isokinetic strength per unit of body mass the effect of playing position was not anymore significant. Future research including maturational assessments is needed during pubertal years. It would also be of interest to investigate the effect of playing position in players accumulating more years of basketball practice. The current ongoing project will report the relationship between isokinetic outputs and concurrent anaerobic tests.
[supported by the Foundation for Science and Technology (FCT), Portugal]
14 ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCETH Wednesday, June 24th, 2009
DIFFERENCES IN PROPRIOCEPTIVE QUALITIES OF THE FOOTBALL PLAYERS AT DIFFERENT LEVELS OF COMPETITION IN
BOSNIA AND HERZEGOVINAHARIS, A., RAðO, I.
FACULTY OF SPORT AND PHYSICAL EDUCATION, UNIVERSITY OF SARAJEVOIntroduction: Football game comprise all forms of natural movements as running, stopping, turning, jumping, falling, throwing, pushing, and occur with different intensity, tempo and duration, with purpose of defending and attacking actions (Raño et al., 2002). Balance abilities of players are very important for the function of maintaining adequate body posture while shooting, pushing, and landing, and especially for injure preventing. Purpose of the research was to find differences in balance ability, propriocetive qualities of players at different levels of competition in Bosnia and Herzegovina.
Methods: Study from the season 2007/2008, involved 129 players, seniors, from different level of competition (five levels): level-I (National team), level-II (Premier League), level-III (First League), level-IV (Second League) and level-V (Cantonal League). Biodex Stability System was used to test balance ability of players, stability level 4, duration of 20sec, stability index was recorded. T-test for independent samples was used for difference determination between levels.
Results: Results of the study has shown statistically significant differences between third (First League) and fourth (Second League) levels.
p.05, in favor of the level four, while between other levels there was no statistically significant differences recorded. Average value of the stability index were as follows: level-I (National Team) 6.1, level-II (Premier League) 6.8, level-III (First League) 7.3, level-IV (Second League) 5.4, level-V (Cantonal League) 6.7.
Discussion: Results of the study didn’t show expected differences between levels of competition. Differences in balance ability were notable only between levels three and four. Differences between levels were expected to be in favor of quality of the competition, but that was not the case (Alic, 2008). We assume that proprioceptive training was disregarded at the all tested levels of competition and that is the reason why there were no differences between levels.
References Alic H. (2008). Defining differences at levels of morphological characteristics, functional and motor abilities of football players at different levels of competition. Master dissertation, Faculty of Sports and Physical Education, Sarajevo.
Raño, I., Talović, M., Dogan M., Bradić,A. (2002). Speed training for soccer player. Faculty of Sports and Physical Education, Sarajevo.
CHANGES IN VERTICAL GROUND REACTION FORCES WITH FATIGUE DURING THE SERVE IN TENNISGIRARD, O., MILLET, G.P., MICALLEF, J.P.
ASPETAR - QATAR ORTHOPAEDIC AND SPORTS MEDICINE HOSPITALIntroduction: Recent biomechanical analyses of the tennis serve have focused on lower extremity kinematics, ground reaction forces (GRF) or EMG activity of selected leg muscles, underlying the importance of a forceful lower limb drive to produce efficient strokes. A decrease in isometric maximal voluntary strength capacity of both knee extensors and plantar flexors has been reported after prolonged tennis playing. However, strength losses with fatigue - as measured previously from isolated leg muscle contractions - do not necessarily reflect changes in lower limb involvement during dynamic/functional movements such as tennis strokes. Therefore, it is still unknown if fatigue alters the lower limb drive during the serve.
The purpose of this study was to examine the impact of prolonged tennis playing on vertical GRF during the serve.
Methods: Nine competitive tennis players randomly executed 10 flat (first, FS), 5 slice (first, SS) and 5 twist (second, TS) serves before and after a 2 h 30 min tennis match. All serve trials were completed from the deuce service court at match pace. Vertical maximal GRF (Fzmax) and post-impact ball velocity were determined for each trial by means of force platform (Captels, France) and radar (Stalker, USA), respectively.
Results/Discussion: Ball velocity did not change from pre- to post-exercise (FS: 158.7±11.5 vs. 154.7±11.5 km.h-1, -2.5%, P=0.099; SS: