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Results: Scores on the Perdue pegboard test showed significant differences between the two age groups (p 0.01) and decreased with age. Tactile-pressure threshold was augmented with increasing age (p 0.05), whereas handgrip strength did not differ between the two age groups. There was a significant relation between the Perdue pegboard test score and tactile-pressure threshold (r = -0.513), but not handgrip strength (r = 0.255).
Conclusions: These results suggested that manual dexterity in hand function was attenuated with increasing age. We considered that this attenuating effect was associated with a decline in tactile sensibility rather than a change in the muscular strength of the hand.
INFLUENCE OF LEG AND HIP STRENGTH ON LOWER BODY INJURIES IN ELITE SNOWBOARDINGPLATZER, H.P., RASCHNER, C., PATTERSON, C.
UNIVERSITY OF INNSBRUCKINTRODUCTION: The overall injury incidence was 1.3 injuries per 1000 runs in the snowboarding FIS World Cup season 2002/2003 (Torjussen and Bahr, 2006). The most common injury location was the knee (18% of all acute injuries). Physical fitness is important for snowboard performance (Platzer et al. 2009), and could be a factor in injury prevention. The aim of this study was to determine the influence of different leg strength parameters on lower body injuries in elite snowboarders.
METHODS: 27 elite Austrian snowboarders took part in this study. The subjects mean values±SD for age, height and body mass were
24.1±4.8 years, 172.6±8.3 cm and 67.1±10.3 kg. All injuries in the season 2007/2008 were recorded during an interview. Concentric and eccentric leg/hip strength and power for flexors and extensors were measured on a Contrex leg press (closed kinetic chain). For statistical analysis t-tests were used to investigate differences between injured and non-injured athletes and to analyse the variation of strength and power between left and right leg/hip. A Phi test was used to correlate gender and standing position with the occurrence of injuries.
RESULTS: In the comparison of front and back legs, all athletes’ back legs had greater absolute and relative eccentric strength and power (p0.01) and lower H/Q-ratios (p0.05). The back legs of the injured group were weaker in relative leg/hip extension (p0.05) and had higher H/Q ratios than the non injured group (p0.05). Injured athletes showed higher bilateral asymmetry in concentric leg/hip extenANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE TH Wednesday, June 24th, 2009 sion (p0.01). There were no group differences in test front leg variables or in leg flexion (p0.05). The Phi test did not show any correlation between gender (Phi=-0.031, p0.05) or standing position (Phi=0.324, p0.05) with lower body injury rate.
DISCUSSION: The results indicate that relative leg/hip extension strength may be important in the prevention of lower body injuries. Eccentric strength is important in the compression phase of the turn in slalom and giant slalom and landings in freestyle and snowboard cross events. The H/Q ratios in the injured group were better, but this could be due simply to the fact that the injured group was weaker in extension and similar in flexion strength. Athletes in alpine sports such as snowboarding and skiing typically have strong quadriceps and often neglect hamstring training. In conclusion, relative leg/hip strength and bilateral leg strength balance are beneficial in preventing lower body injuries.
REFERENCESPlatzer HP, Raschner C, Patterson C (2009). Comparison of physical characteristics and performance among elite snowboarders. J Strength Cond Res, in press.
Torjussen J, Bahr R (2006). Injuries among elite snowboarders (FIS Snowboard World Cup). Br J Sports Med, 40:230-234.
14:00 - 15:30 Oral presentations OP-ST03 Sports 3
PROPELLING EFFICIENCY IN MASTER SWIMMERSZAMPARO, P., MASSEI, E., GATTA, G., BENELLI, P.
UNIVERSITY OF VERONAINTRODUCTION. When the swimming records in master competitions are evaluated, it becomes apparent that performance (e. g. maximal speed, vmax) decreases steadily as a function of age. In Italian front crawl swimmers the decrease is of about 0.2 m/s every 10 years of age in short distance (50 m) races and of about 0.1 m/s every 10 years of age over long distance (800 m) races. AIMS. The aim of this study was to investigate if this decrease could be related to a decrease in the propelling efficiency (ηP) of the arm stroke. This work stems from a previous study  where this parameter was investigated in children and adults (9-59 yrs of age) of good technical skill but where the adult swimmers were not attending master competitions. SUBJECTS. 61 male master swimmers were tested. They were divided into 4 classes of age: M1: 20-29 yrs (25.9±3.2, n = 17); M2: 30-39 yrs (34.8±2.7, n = 22); M3: 40-49 yrs (44.3±3.1, n = 12); M4: 50-59 yrs (54.1±3.0, n = 10). No major differences in the anthropometric characteristics were found in these subjects even if stature tended to decrease (1.81 vs. 1.77 m) and body mass to increase (72 vs. 78 kg) from M1 to M4. PROTOCOL. The subjects were asked to swim a 25 m pool length at constant speed and to repeat the swim at six different, incremental speeds (from slow, to moderate, to maximal). During each trial, average speed (v) and stroke frequency (SF) were measured in the middle 10 m of each lane. The distance per stroke (DS) was calculated from the ratio v/SF and ηP was estimated according to the simple model proposed by , on the basis of values of v, SF and of the shoulder to hand distance. RESULTS. The values of v (1.48, 1.42, 1.34, 1.06 m/s), SF (0.87, 0.86, 0.85, 0.69 Hz) and DS (1.74, 1.70, 1.61, 1.52 m) attained at vmax (in M1, M2, M3 and M4, respectively) show a steady decrease as a function of age. In M1, M2 and M3 both DS (1.9-2.0 m) and ηP (0.28-0.30) show a plateau at slow to moderate speeds whereas in M4, DS and ηP show a continuous decrease with increasing speed and are, even at their top (1.7 m and 0.23, respectively), lower than in the other classes of age. DISCUSSION. Between 20 and 50 yrs, ηP at vmax decreases of about 2% per decade (the decrease in vmax is similar: about 3% per decade). Between 50 and 60 yrs, ηP decreases to a larger extent (about 14%) yet less than the decrease in vmax (about 21% in this decade). This suggest that in masters up to 50 years of age the decrease in performance can be essentially attributed to a decrease in propelling efficiency but that, after this age, also other factors should be taken into account to explain the decrease in swimming performance.
REFERENCES Zamparo P, DR Pendergast, J Mollendorf, A Termin, AE Minetti. (2005) An energy balance of front crawl. Eur J App Physiol 96: 459-470  Zamparo P (2006) Effects of age and gender on the propelling efficiency of the arm stroke Eur J App Physiol 97: 52 – 58
COMPARATIVE METHOD TO ESTIMATE PROPELLING ABILITYKARSAI, I., SILVA, A., GARRIDO, N., LOURO, H., LEITAO, L., MAGYAR, F., ÁNGYÁN, L., ALVES, F.
UNIVERSITY OF PÉCSINTRODUCTION: Producing propelling force in an efficient way in the right swimming direction is one of the key factors in competitive swimming. During the action the extremities of the swimmer give energy to the water molecules to accelerate them, to generate flow around and along the hand-arm complex to achieve the highest pressure difference in the right time and space. There are differences in morphological and physical characteristics between swimmers and there is an infinite number of possible motion variations to perform the crawl arm stroke. Difference should exist between swimmers, and in the way they can exploit the potential of the fluid environment.
Direct force measurement is impossible during free swimming and the analitical investigations up to date did not provide a useful method to calculate the force production, therefore a special approach is necessary to express the level of the propelling ability.
METHODS: 8 internationally recognised male swimmers (19,8 ±0,9 yrs, 73,9 ±6,0 kg, 181,7 ±5,5 cm) were asked to perform the nonbreathing, only arm task on a special device which recorded the force (f=200). The legs were tied and supported. The starting frequency (FR) was set at f=0,5 Hz and was increased with f=0,083 Hz steps till the swimmer could maintain the stabil rhythm. 4 underwater cameras (50 Hz) were used to record the kinematic parameters and the APAS system was employed to calculate the 3D data for the analysis.
Reference forces were calculated based on anthropometric and kinematic data with a 3-segment simple model concerning the drag equation without the C value and a projection to the swimming direction were related to the measured force data. The Pearson correlation was employed between the 100m sprint velocity and the result to test the suitability of the method.
RESULTS: The main force at the starting FR were 50,6 ±21,9 N. The force production increased almost in a linear fashion and peaked at the f=0,65 Hz: 76,2 ±24,5 N and dropped considerably at the highest FR value. The ratio between the measured and the reference force
at the starting FR: 2,04 ±0.68 the value is almost constant for the individuals across the FR increments, with a little peak around the 3rd step. Free swimming velocity was measured in 100m distance v=1.92 ±0.07 m/sec. The study showed significant correlation between the calculated ratio and the velocity swam in 100m (r=0.749, p0.05).
DISCUSSION: The measured force difference caused by the unsteady effects of this dinamic experimental setup showed a litle higher value as it was reported by other experimental and analitical studies (CFD), where the quasy-steady and unsteady effects were investigated.
The result indicates that this method fits the requirement to estimate the propelling ability of individuals, whereas the result can provide the magnitude which can differentiate between swimmers but not the way they do it.
DOES THE KICK FREQUENCY AT THE SURFACE AFFECT THE PHYSIOLOGICAL RESPONSES IN INTERNATIONAL MONOFIN-SWIMMERS ?VERCRUYSSEN, F., BOITEL, G., BOURDON, L., BRISSWALTER, J.
1. UFR STAPS, UNIVERSITÉ DE TOULON-VAR, LA GARDE, FRANCE, 2. IMNSSA, HÔPITAL ST ANNE, TOULON, FRANCEIntroduction: The criteria which determine the relationship between the energy demand and the movement pattern in terrestrial activities depend strongly on the locomotion mode (Cavanagh & Williams, 1982; Marsh & Martin, 1997). In the context of aquatic locomotion, a great fraction of the energy demand is utilized to overcome drag. In monofin-swimming during which the subject produces continuously local forces during up and down movements at the surface from his fin, it has been hypothesized that one of the variables on which swimmers can work for improving performance is the kick frequency (Nicolas et al., 2007). The large variations of this parameter might affect the propelling characteristics at the surface and thereby, the drag and the associated energy demand. The objective of this study was to evaluate the effect of kick frequency on the energy demand and physiological responses induced in monofin-swimmers of international calibre.
Methods: Eight international monofin-swimmers (mean age: 18 ± 2.5 yr; mean weight: 70.5 ± 9 kg; mean height: 171 ± 8.8 cm) completed two testing sessions in a 50-m outdoor swimming pool. The first session consisted of a maximal test performed on a distance of 600-m in order to determine the oxygen uptake at the end of exercise (i.e. VO2 600m) but also, the mean speed obtained on the test (V600m).
The second session was performed at a constant swimming intensity of 90% V600m composed of five bouts at different kick frequencies (600m exercise, 3-min rest). The first bout was systematically conducted at the freely chosen kick frequency (FCKF) and the other bouts (FCKF-15%, FCKF-10%, FCKF+10%, FCKF-20%) were presented in a random order. During the incremental and constant conditions, gas exchange was measured breath by breath with a portable system (K4b2, Cosmed, Rome, Italy) connected to a snorkel (Aquatrainer;
Results: Mean values for oxygen uptake (Vo2) were significantly reduced at FCKF+10% compared to FCKF-15% and FCKF-20%. However, no significant variations in heart rate (HR), ventilation (VE) and blood lactate concentrations ([La-]b) were observed between the conditions.
Discussion: The main results of this study indicated that the kick frequency selected by elite monofin-swimmers affects the energy demand during a constant swimming trial. Interestingly, the reduction of VO2 observed at the FCKF+10% suggests that the organisation of the movement pattern is different than those induced in terrestrial activities (e.g. Cavanagh & Williams, 1982; Marsh & Martin, 1997).
Given the lack of significant variations in ventilatory parameters among the conditions, the differences in energy demand between the FCKF+10% bout and sub-frequencies might derive from different intrinsic muscular mechanisms.
References Cavanagh PR, Williams KR (1984). Med Sci Sports Ex, 14, 1518-1522.
Marsh AP. Martin PE (1997). Med Sci Sports Ex 29, 1225-1232.
Nicolas G, Bideau B, Colobert B, Berton E (2007). Hum Mov Sci 26, 426-442.
CORRELATION BETWEEN OXYGEN UPTAKE KINETICS IN SEVERE INTENSITY SWIMMING AND ENDURANCE PERFORMANCEREIS, J., ALVES, F., VLECK, V., BRUNO, P., MILLET, G.P.
FACULTY OF HUMAN KINETICS, LISBONIntroduction: Faster O2 kinetics has been associated with a lower O2 deficit and greater tolerance to fatigue but it is unclear whether it is a determinant of endurance performance. This study investigated the relationships between VO2 kinetics parameters within constant load severe intensity swimming, and 400m swimming performance.
Methods: Fourteen national level Portuguese swimmers (age 20.5 ± 3.0 yr.; mass 75.4 ± 12.4 kg) performed first a discontinuous incremental freestyle test (FS_EXT) and then two 7-min constant velocity freestyle swims (FS_CTA and FS_CTB), in a 50m pool, over a 10 day period. Cardiorespiratory analysis of expired air was performed in all three tests, which were each separated by at least 24h rest, using a breath by breath analyser (K4b2, Cosmed, Italy) and swimming snorkel (Aquatrainer, Cosmed, Italy).