5- ENTRAÎNEMENT (DIVERS)

Aitken DA, Jenkins DG  : Anthropometric-based selection and sprint kayak training in children. J Sports Sci 1998 Aug;16(6):539-43

Performance Enhancement Centre, Queensland Academy of Sport, Woolloongabba, Australia.

A 12 week kayak training programme was evaluated in children who either had or did not have the anthropometric characteristics identified as being unique to senior elite sprint kayakers. Altogether, 234 male and female school children were screened to select 10 children with and 10 children without the identified key anthropometric characteristics. Before and after training, the children completed an all-out 2 min kayak ergometer simulation test; measures of oxygen consumption, plasma lactate and total work accomplished were recorded. In addition, a 500 m time trial was performed at weeks 3 and 12. The coaches were unaware which 20 children possessed those anthropometric characteristics deemed to favour development of kayak ability. All children improved in both the 2 min ergometer simulation test and 500 m time trial. However, boys who were selected according to favourable anthropometric characteristics showed greater improvement than those without such characteristics in the 2 min ergometer test only. In summary, in a small group of children selected according to anthropometric data unique to elite adult kayakers, 12 weeks of intensive kayak training did not influence the rate of improvement of on-water sprint kayak performance.

PMID: 9756258, UI: 98427689

Arlettaz A., Rieth N.* and Courteix D. Évaluation des masses musculaires et des densités osseuses régionales chez des kayakistes de haut niveau. Science & Sports; 19, 4 , 2004, 199-201.
*Corresponding Author Contact Information, E-mail The Corresponding Author
Laboratoire de la performance motrice, université d’Orléans, rue de Vendôme, BP 6237, 45062, Orléans cedex 2, France
5 Mai 2003; accepté le: 29 Août 2003. Available online 10 February 2004.Abstract
Objectif. – Étudier la composition corporelle et la densité osseuse chez des adolescents pratiquant intensivement le kayak.
Matériels et méthodes. – Quatorze adolescents répartis en deux groupes appariés ont participé à l’étude. Les sportifs (n = 7) s’entraînaient 10 h par semaine, les témoins (n = 7) faisant moins de 4 h de sport hebdomadaire. La composition corporelle et la densité osseuse ont été évaluées par DXA.
Conclusion. – La pratique intensive du kayak semble favoriser le développement de la masse musculaire et améliorer la densité osseuse dans les régions préférentiellement sollicitées par ce sport (bras, tronc).

Mots-clé: Kayak; Adolescent; Densité osseuse; Composition corporelle

BISHOP D, BONETTI D, and DAWSON B: The effect of three different warm-up intensities on kayak ergometer performance. Med. Sci. Sports Exerc,.Vol. 33, No. 6, 2001. pp. 1026-1032.
Department of J-Iu,nan Movement and Exercise Science, University at Western Australia, Nec/lands, WA 6907, AUSTRALIA
ABSTRACT
Purpose : The purpose of this study was to investigate the influence of warm-up (WU) intensity on supramaxinial kayak ergometer performance. Methods: in the initial testing session, eight institute of sport kayak squad members performed a graded exercise test for determination of VO,,,, and lactate (La) parameters. In a random, counterbalanced order, subjects subsequently performed WU for 15-min at either their aerobic threshold (WI). their anaerobic threshold (W3). or midway between their aerobic threshold and anaerobic threshold (W2). A 5-min passive rest period and then a 2-min. all-out kayak ergometer test followed the WU. Results: For the three different WV conditions, no significant differences were observed for average power, peak V'O2, total V'O2, total V'CO2 or accumulated oxygen deficit (AOD) during the 2-min test. However, when compared with W3. differences in average power approached significance after both WI (P = 0.1)9) and W2 (P = 0.10). Furthermore. when compared with W3, average power during the first half of the 2-min test was significantly greater after W2 (P < 0.05) and approached significance after WI (P = 0.06). After each WU period, there was a significant difference in blood pli (WI >W2>W3; P < 0.05) and blood [Lai (W I <W2<W3: P 0.05). Despite the significantly different metabolic acidemia after each WV condition, there were no significant differences in the VO, responses to the 2-min test. However, the greater metabolic acidemia after V3 was associated with impaired 2-min kayak ergometer performance. Conclusions: It was concluded, that although a degree of metabolic acidemia may be necessary to speed 02 kinetics, if the WU is too intense, the associated metabolic acidemia may impair supramaximal performance by reducing the anaerobic energy contribution and/or interfering with muscle contractile processes. Key Words: ACCUMULATED OXYGEN DEFICIT. METABOLIC ACIDOSIS. PRIOR EXERCISE. O KINETICS

BISHOP D, BONETTI D & SPENCER M : The effect of an intermittent, high-intensity warm-up on supramaximal kayak ergometer performance. Journal of Sports Sciences, 2003, 21, 13-20

School of Human Movement and Exercise Science, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
Accepted 7 October 2002
It has previously been shown that the metabolic acidaemia induced by a continuous warm-up at the 'lactate threshold' is associated with a reduced accumulated oxygen deficit and decreased supramaximal performance. The aim of this study was to determine if an intermittent, high-intensity warm-up could increase oxygen uptake (V'O2) without reducing the accumulated oxygen deficit, and thus improve supramaximal performance. Seven male 500 m kayak paddlers, who had represented their state, volunteered for this study. Each performed a graded exercise test to determine V'O2ma,, and threshold parameters. On subsequent days and in a random, counterbalanced order, the participants then performed a continuous or intermittent, highintensity warm-up followed by a 2 mi all-out kayak ergometer test. The continuous warmup consisted of 15 min of exercise at approximately 65% V'O2m. The intermittent, highintensity warm-up was similar, except that the last 5 min was replaced with five 10 s sprints at 200% J'O2m separated by 50 s of recovery at 55% 002m. Significantly greater (P< 0.05) peak power (intermittent vs continuous: 629 ± 199 vs 601 ± 204 W) and average power (intermittent vs continuous: 328 ± 39.0 vs 321 ± 42.4 W) were recorded after the intermittent warm-up. There was no significant difference between conditions for peak 1702, total VO2 or the accumulated oxygen deficit. The results of this study indicate that 2 min all-out kayak ergometer performance is significantly better after an intermittent rather than a continuous warm-up.
Keywords: accumulated oxygen deficit, metabolic acidosis, prior exercise.

Cezard J-P : Reflexion sur le renforcement musculaire en canoë-kayak. Doc. INSEP 1982;Paris, 25 p.

Echocardiographic data on 21 top-grade kayak- canoeists and 16 top-grade handball players are compared. While the end-diastolic and end-systolic diameters as well as end-diastolic and end-systolic volumes did not appreciably differ, the posterior wall and particularly the interventricular septum both in diastole and systole were significantly thicker in kayak- canoeists than in handball players. Also the left ventricular mass was considerably greater in the former group. The differences were even more striking when the parameters in question were calculated in relation to 1 kg body weight, 1 m-2 height and 1 m2 body surface area. Since the members of both groups were competitors at international level, it can be assumed that the differences are due to the different degree of strain placed on the heart in these sports.

MEDLINE - PMID: 6233088, UI: 84206804

The echocardiographic parameters were followed for 3 years in 15 boys aged 13 years on average, who were beginning competitive canoe race training, and were compared with the corresponding data on 17 boys of the same age who did not take part in sports. As compared to non-sporting boys the 13-year-old canoeist boys had a larger left ventricular end-diastolic diameter (46.13 +/- 4.64 mm vs 44.35 +/- 3.06 mm), a thicker left ventricular posterior wall (7.47 +/- 0.74 mm vs 6.47 +/- 1.18 mm) and particularly a thicker interventricular septum (8.33 +/- 1.18 mm vs 7.59 +/- 1.6 mm) just after they began sport, in spite of the fact there were no significant differences between the two groups in age, height, weight and body surface area. The preexisting difference in left ventricular hypertrophy between the two groups increased significantly during the 3-year follow-up period. The thickness of the left ventricular posterior wall in diastole increased to 9.20 +/- 1.01 mm vs 8.24 +/- 0.83 mm (p = 0.006), and that of the interventricular septum to 10.73 +/- 1.58 mm vs 9.59 +/- 1.18 (p = 0.025). The hypertrophic index and the left ventricular mass corresponded to the data given above (9.97 +/- 1.25 mm vs 8.91 +/- 0.94 mm, p = 0.01; and 261 +/- 50.7 g vs 202.83 +/- 45.8, p = 0.002, respectively). The canoeist boys had a slightly larger aortic root diameter at the beginning, and this difference increased and became more significant during the 3 years (29.4 +/- 2.39 mm vs 27.18 +/- 1.88 mm, p = 0.006). There were no significant differences between the two groups in the size of the left atrium, the fractional shortening of the left ventricle and the calculated ejection fraction and stroke volume.

MEDLINE - PMID: 2949471, UI: 87123102

Type de document : PERIODIQUE. Langue : Français. Cote INIST : 21171. Editeur : France

Five hundred twenty-eight male athletes participating in 26 Olympic events and298 female athletes participating in 15 Olympic events underwent determinationof body fat percentage (% fat) and lean body mass (LBM) via hydrostaticweighing and/or anthropometric methods. All groups of athletes were below theaverage values for % fat of college age men and women of 15% and 25%,respectively. In general, athletes involved in a sport where their body weightis supported, such as canoe and kayak (males, 13.0 +/- 2.5%; females, 22.2 +/-4.6%) and swimming (males, 12.4 +/- 3.7%; females 19.5 +/- 2.8%), tended tohave higher % fat values. Athletes involved in sports where a weight class hasto be made to compete, such as boxing (males, 6.9 +/- 1.6%) and wrestling(male, Junior World Freestyle 7.9 +/- 2.7%), events such as the 100, 200, and400 meters in athletes (male 100 and 200 meters, 6.5 +/- 1.2%; female 100, 200and 400 meters, 13.7 +/- 3.6%) that are very anaerobic in nature and extremelyaerobic events such as the marathon (males, 6.4 +/- 1.3%) demonstrated lower %fat values. Athletes involved in sports where body size is a definiteadvantage, such as basketball (males, 84.1 +/- 6.2 kg; females, 55.3 +/- 4.9kg) and volleyball (males, 75.0 +/- 6.6 kg; females, 58.4 +/- 4.5 kg) tended tohave a larger LBM.

MEDLINE - PMID: 6650717, UI: 84077403

Department of Human Movement and Recreation Studies, University of Western Xustralia, Nedlands.

ISSN: 0195-9131. Language: ENGLISH

Physical and physiological factors accounting for the variability ofperformance in 500, 1000, 10,000, and 42,000 m flatwater kayaking were reinvestigated using linear regression. Times achieved for each distance we used as the dependent variable for analysis while the independent variables were the parameters derived from the test battery. The 38 kayakists who participated were categorized as either state team members or nonselected paddlers, based on an objective selection policy. Several of the participant subjects were Australian international representatives. All selected paddlers were grouped together and Student's t-tests performed to determine which variables could distinguish between selected and nonselected paddlers. Simple regression was used to determine the strength of association of each parameter with performance time over each race distance, and multiple regression was used to generate equations for the prediction of performance times. Aerobic power and variables related to the aerobic-anaerobic transition were examined using gas analysis during an incremental workload test on a kayak ergometer. A 1-min all-out test also on a kayak ergometer was used to obtain an indication of anaerobic capacity and power. Muscular strength and fatigue were assessed using a simulated kayak stroke on a Cybex isokinetic dynamometer. Physical characteristics were determined using kinanthropometric tests. Aerobic power, anaerobic power and capacity, muscular strength, resistance to muscular fatigue, and measures of body size were significantly greater in more successful kayakists. All of the parameters measured correlated significantly with performance time over at least one of the four race distances. (ABSTRACT TRUNCATED AT 250 WORDS)

Tags: Human; Male. Descriptors: *Anthropometry; *Physical Endurance--Physiology--PH; *Sports ;Adaptation, Physiological--Physiology--PH; Adult; Australia; Body Mass Index; Competitive Behavior--Physiology--PH; Physical Education and Training; Water CAS Registry No.: 7732-18-5 (Water)

University of Western Australia, Nedlands.

Immune suppression has been suggested to occur as a result of acute exercise although results of previous studies are variable, possibly due to the failure of some researchers to control exercise intensity and duration. Most of the studies so far have investigated immediate effects after bouts of exercise mainly in subjects undertaking lower body exercise (running or cycling), andthe time course of recovery has rarely been determined. We chose two groups of athletes for our studies. One group represented subjects of a range of fitness levels from recreational runners to high-performance runners. The second groupre presented kayakists with a similar range of fitness levels. Following interval training designed to stress either the lower or upper body anaerobically, we have now shown that upper body exercise (kayaking) induces similar in vitro responses to those described for lower body exercise. There were no differences between the responses of low-fitness versus high-fitness subjects. In addition we have studied the in vitro responses of leukocytes following acute anaerobic exercise over a 24-h recovery period. The resultsshowed that the reduced lymphocyte proliferative response, in vitro, to theT-cell mitogen CONA experienced immediately after exercise returned to normal levels within 2 h of recovery time. This suggests that the reduction in lymphocyte proliferative response is a short transient one.

MEDLINE - PMID: 1549029, UI: 92195091

Iglesias Cubero G, Batalla A, Rodriguez Reguero JJ, Barriales R, Gonzalez V, de la Iglesia JL, Terrados N. Left ventricular mass index and sports: the influence of different sports activities and arterial blood pressure.Int J Cardiol 2000 Sep 15;75(2-3):261-5

Cardiology Department, Hospital Central de Asturias, c/Julian Claveria s/n, 33006, Oviedo, Spain.

The mechanisms by which endurance training produces physiological hypertrophy have been thoroughly investigated but not with young athletes. The aim of our study was to investigate arterial blood pressure exercise responses in young athletes who started heavy training by the age of 11, participating in metabolically different sports (cycling, kayaking, and soccer) and to analyse the influence that arterial blood pressure at maximum exercise and VO(2) max could have on the development of cardiac mass in these subjects. SUBJECTS AND METHODS: We studied a group of well trained normotensive male subjects, comprising 37 cyclists, 15 soccer players and 12 canoeists (mean age, 16+/-1 years). Evaluation included a clinical history and physical examination, M-mode and two-dimensional echocardiography, 12-lead resting electrocardiogram and a graded exercise test with direct determination of VO(2) max. Systolic and diastolic blood pressure were measured at rest and maximum exercise. Determination of the left ventricular mass index (LVMI) was performed using Devereux's formula with correction for the body surface area. RESULTS: Cyclists showed values of LVMI in g m(-2) significantly higher than those of other subjects (123 vs. 92 and 113). Canoeists showed the maximal arterial blood pressure at maximum exercise in mmHg (190 vs. 172 and 170) and cyclists showed the maximal VO(2) ml kg(-1) min(-1) uptake (57.6 vs. 48.5 and 53.3). A linear correlation was found between LVMI and VO(2) max (r=0.4727, P<0.001) and this correlation was also significant with systolic blood pressure at maximum exercise (r=0.2909, P<0.01). No differences in LVMI were found when comparing those subjects who presented systolic blood pressure at maximum exercise equal or greater than 195 mmHg with those who presented less than this value. CONCLUSIONS: It can be concluded that VO(2) max is the variable that better correlates with the LVMI. Athletes who reach greater systolic blood pressures at peak exercise have a tendency to develop greater LVMI. In comparison with soccer players and canoeists, cyclists are the sportsmen who develop a greater LVMI and VO(2) max.
PMID: 11077144 [PubMed - indexed for MEDLINE]

Department of Biochemistry, Institute of Sport, Warsaw, Poland.

Plasma cortisol and testosterone levels were examined in five, elite, male kayakers before and after 19-km and 42-km kayak races. Both races resulted in significant elevation in plasma cortisol and observed increase is likely to depend on race duration, being much more pronounced after 42-km race compared to 19-km. It should be stressed that observed elevation in cortisol level after 42-km race was higher than reported previously after a marathon run. This finding is in line with reports on hormonal changes in response to arms exercise. Both contests caused a decrease in plasma testosterone level, but the difference between races was not significant. Testosterone/cortisol ratio dropped significantly immediately after the races and the observed decrease was more dominant after the 42-km distance. On the next day, 18 h after the races plasma cortisol, testosterone levels and T/C ratio returned to basal level indicating recuperation from post exercise changes.

MEDLINE - PMID: 1806731, UI: 92219616

Department of Kinesiological Anthropology, Faculty of Physical Education, University of Zagreb, Croatia.

ISSN: 0022-4707. Language: ENGLISH. Document Type: JOURNAL ARTICLE. Journal Announcement: 9301. Subfile: INDEX MEDICUS

A study of anthropometric and functional characteristics was conducted in a sample of 29 athletes, flatwater racers 18 kayakers and 11 canoeists. The results of morphological tests suggest an evident reduction of subcutaneous fat, above-average values of limb circumferences (especially upper limbs) and of body mass, attributable to a high proportion of lean body mass. Trunk extension strength was to be below the average, while the strength of the remaining analyzed static movements were on the level of trained persons. Aerobic capacity, i.e. the functioning of the cardiopulmonary system, in the sample under discussion has shown above-average values, comparable to those obtained in athletes in the aerobic sports group. The results of discriminant analysis applied separately to morphological, dynamogenic and aerobic characteristics with the aim to identify possible differences between the two sports suggest that our sample constituted a homogeneous group, regardless of which of the two sports were practiced.

Tags: Human; Male. Descriptors: *Anthropometry; *Sports; Adipose Tissue--Physiology--PH Adolescence; Adult; Biomechanics; Body Height; Oxygen Consumption; Physical Endurance; Respiratory Mechanics

Department of Orthopaedic Surgery, Kansai Medical University, Osaka 570-8507, Japan.

We gave a sports injury questionnaire survey to 821 active canoeists, members of the Japan Canoe Association (JCA), and performed a medical check of 63 top competitive JCA canoeists, including physical and laboratory tests and radiographic examinations of the chest, spine, shoulder, elbow, and wrist joints. Completed questionnaires were returned by 417 canoeists, whose reported racing styles were: kayak, 324; Canadian canoe, 71; slalom, 13; and not specified, 9. Of the 417 respondents, 94 canoeists (22. 5%) reported that they experienced lumbago; 20.9% experienced shoulder pain; 3.8%, elbow pain; and 10.8%, wrist pain. On medical examinations, lumbago was found to be mainly of myofascial origin or due to spondylolysis. Impingement syndrome was also observed in 4 canoeists with shoulder problems. The competitive canoeists had low blood pressure, and some had bradycardia. On laboratory examinations, serum hemoglobulin, hematocrit, high-density lipoprotein cholesterol (HDL-CHO), creatine phosphokinase (CK), and creatine (CRTN) in the top competitive canoeists showed high values in comparison with those of an age-matched control group. However, low serum total cholesterol (TP) values were observed in the top competitive canoeists.

PMID: 10436270, UI: 99367779

Postgraduate School of Sports Medicine, University of Rome, Italy.

ISSN: 0733-8651. Language: ENGLISH. Document Type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL. Journal Announcement: 9208. Subfile: INDEX MEDICUS

Athletic training induces a morphologic adaptation of the heart, by increasing left ventricular cavity size and wall thickness. Wall thickening usually ranges up to 12 mm, but in 2% of athletes it may be more marked (13-15 mm). Athletes with the most substantial wall thickening are rowers, canoeists, and cyclists, competitive at elite levels for a substantial period of time. Therefore, physiologic left ventricular hypertrophy probably does not exceed 16mm in thickness and is usually present in the ventricular septum, associated with an enlarged cavity size. Additional features of the physiologic left ventricular hypertrophy are the regression of wall thickening into normal limits (less than 13 mm) after a period of deconditioning and the consistent normality of the Doppler diastolic filling pattern. (51 References)

Tags: Human. Descriptors: *Heart--Anatomy and Histology--AH; *Heart Hypertrophy--Pathology-PA; *Sports; Diagnosis, Differential; Echocardiography; Heart Hypertrophy--Ultrasonography--US

Fundacion Deportiva Municipal de Aviles, Spain.

PURPOSE: The use of different wash-riding techniques is common during kayak training and competition. Changes in wash-riding positions could imply a different exercise intensity. The aim of this study, therefore, was to quantify the energy savings made when a kayaker is "wash riding."

METHODS: Eight male international flat water kayakers, who performed a field test of 2000 m in each of the four wash-riding positions, head (H), right wave (RW), left wave (LW), and end position (V), were studied. The data investigated were: time, stroke rate, blood lactate (BL), heart rate (HR), and rate of perceived exertion (RPE). Under laboratory conditions kayakers performed the same intensity of exercise in a kayak ergometer, and HR, oxygen uptake (VO2), BL, mean power output (W), and RPE were measured.

RESULTS: The results show significant differences (P < 0.05) among H, RW/LW, and V. The mean values for BL (P < 0.05) were 4.2, 2.0, 2.2, and 1.5 mmol.L-1, for H, RW, LW, and V, respectively. RPE also revealed differences, with values of 15, 12.6, 12.6, and 9.7 for H, RW, LW, and V, respectively. Mean power output gave values of 190.3 (H), 155.6 (RW and LW), and 129.5 (V) W. HR was different between H and V (172 and 151), while stroke rate was different among the parameters H, RW, and V (93.7, 88.8, and 87.6, respectively). The VO2 in the kayak ergometer test showed a difference between H and V (3.78 and 2.23 L.min-1).

CONCLUSIONS: We conclude that "wash riding" involves a saving in energy cost of between 18% and 31.9%, depending on the position. This conclusion is of importance for the quantification and calibration of kayak training and competition.

Sitkowski D. Some indices distinguishing olympic or world championship medallists in sprint kayaking. Abr source Biol Sport, 2002, Vol 19, Iss 2, pp 133-147

Address :Sitkowski D, Inst Sport, Dept Physiol, Warsaw, POLAND
Author KW :exercise and anthropometric attributes; male and female sprint kayakers; longitudinal study
KW Plus SKELETAL-MUSCLE; BLOOD LACTATE; ARM EXERCISE; KAYAKIERS;
RESISTANCE; PADDLERS; STRENGTH; ROWERS

Abstract : Thirty male and female sprint kayakers - mostly participants in world championships and/or Olympic Games - were investigated in the present study. The subjects were divided into the medal-winning (5 females and 6 males) and the less successful (10 females and 9 males) groups of kayakers. Ln all the subjects, basic anthropornetric parameters were estimated and the following exercise tests were carried out: the 40-s upper body anaerobic performance test and the graded exercise test on the kayak ergometer followed by the 2-mm (for the women) gr 4-mm (for the men) maximal exercise. With the former exercise test, the amount of work performed (W-tot) and the maximal power (P-max) were determined, while the latter one was used for estimating the power (P-AT4) and oxygen uptake at anaerobic
threshold (VO2AT4), mean power of the maximal exercise (P-m) maximal oxygen uptake (V(overdot)O(2)max), and the blood lactate level (LA). The results indicate that, apart from body height in females which was significantly shorter in the medallist group, the anthropometric parameters did not distinguish the medal-winning kayakers from their less successful counterparts. In terms of the exercise parameters, in the males only the anaerobicperformance indices (W-tot, J(.)kg BM(-1); P<0.01, and W-tot J(.)kgFFM(-1); P<0.001 in juniors, and P-max, W(.)kgBM(-1), W-tot, kJ; P<0.05, W-tot, J(.)kgBM(-1), and W-tot,
J(.)kgFFM(-1); P<0.01, in seniors) were significantly elevated in the medallists compared to the less successful kayakers. In case of the female athletes, the medallists exhibitedsignificantly elevated P-m expressed in W.kgBM(-1) (P<0.05 in both juniors and seniors), W -tot expressed in J(.)kgBM(-1) (P<0.01 in juniors and P<0.05 in seniors) and in J(.)kgFFM(-1) (P<0.05 in both juniors and seniors), P-rn expressed in W (P<0.05 in juniors and P<0.01 in seniors), in W.kgBM(-1) (P<0.01 in both juniors and seniors) and in W.kgFFM(-1) (P<0.01 in juniors and P<0.05 in seniors), and P-AT4 expressed in W(.)kgBM(-1) in juniors, and in
W(.)kgFFM(-1) in seniors (P<0.05 in both juniors and seniors). In addition, in the female kayakers a significant correlation was detected between W-tot and P-rn (P<0.01 and P<0.05, for juniors and seniors respectively). In conclusion, the present results demonstrate that from the parameters tested the total work performed in the upper body anaerobic performance test, expressed in relative units, can be regarded as the most useful selection index in sprint kayaking.

Smith PJ, Davies M : Applying contextual interference to the Pawlata roll. J Sports Sci 1995 Dec;13(6):455-462

Division of Health and Human Performance, University of Wales, Bangor, Gwynedd, UK.

Contextual interference is manipulated by changing the practice order of anumber of similar motor tasks, so that the learning context of each interferes with that of the other. The effect has been found to generalize to baseball batting, badminton serving and volleyball skills. The present study examined whether this practice technique could be applied to a Pawlata roll in a kayak. The study was further motivated by the fact that many instructors in Britain currently advocate learning the Pawlata roll in one direction only to a criterion of accuracy, thereafter transferring to the opposite direction. Contextual interference literature predicts that skill retention would be better served by practising on alternate sides. Accordingly, 16 undergraduate students with no kayaking experience were randomly allocated to either a low contextual interference group, which followed U'ren's (1993) recommendations, or a high contextual interference group, which practised the skill on alternate sides. The high contextual interference group took less time to acquire the skill, and were also quicker to achieve successful performance in retention (full roll) and transfer (half roll) tests, regardless of the direction of the roll, 1 week later. The time savings in practice were not expected, as acquisition under high contextual interference was improved rather than impaired. This finding suggests that bilateral transfer was increased by randomizing practice. These results are worthy of further investigation, in that they suggest that the recommended training methods may not be optimal.

Publication Types: Clinical trial. Randomized controlled trial

MEDLINE - PMID: 8850571, UI: 97003232

Wozniak A, Drewa G, Wozniak , DrewaT, Olszewska D, MilaKierzenkowska C, Rakowski A, Brzuchalski M: Effect of cryogenic temperatures and exercise on antioxidant enzymes activity in erythrocytes of kayakers. Biol Sport, 2002, Vol 19, Iss 1, pp 63-72

Address :Wozniak A, Ludwik Rydgier Med Univ, Dept Biol, Karlowicza 24, PL-85092 Bydgoszcz, POLAND
Author 1KW cryogenic chamber; superoxide dismutase (SOD); catalase (CAT); glutathione
peroxidase (GSHPx)- KW Plus RED-BLOOD-CELLS; SUPEROXIDE-DISMUTASE; URIC-ACID; EXPOSURE

Abstract : In the present study we have investigated the influence of cryogenic temperatures and exercise on antioxidant enzyme activity in the erythrocytes of kayakers. Activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSHPx) have been assayed. The study was performed on 10 kayakers (Polish Olympic Team) who were training for 31 days to prepare for a competition. In the first ten days of training sportsmen additionally had a cryogenic chamber sessions. The blood samples were taken: before the start of the study, after the fifth and the tenth day of training accompanied with cryostimulation and on the seventh, fourteenth and twenty first day of exercise without cryogenic stimulation. GSHPx activity significantly increased after the fifth day of training and cryostimulation and decreased significantly after tenth day of training and cryostimulation. CAT activity did not show statistically significant increase after the fifth day of training and cryogenic session and a statistically significant decrease was observed on the tenth day. Training performed after the end of cryostimulation did not have statistically significant influence on SOD activity. Activity of CAT significantly decreased on the fourteenth day of training and GSHPx decreased significantly on the 21(st) day of exercise not preceded by cryostimulation. It is difficult to estimate the influence of cryogenic session
on pro- and antioxidant mechanisms during exercise.