2- BIOMÉCANIQUE

 Clarkson PM, Kroll W, Melchionda AM : Isokinetic strength, endurance, and fiber type composition in elite American paddlers. Eur J Appl Physiol Occup Physiol1982;48(1):67-76

Muscle fiber type and isokinetic strength and fatigue were examined in nine highly trained canoe and kayak paddlers. Needle biopsies were taken from the right vastus lateralis and biceps brachii muscles and the samples stained for myofibrillar ATPase. Baseline elbow flexion and knee extension isometric (0 degrees . s-1) and isokinetic (60 degrees . s-1 or 1.05 rad . s-1 and 180 degrees . s-1 or 3.14 rad . s-1) peak torques were determined. Each subject then performed two series of 50 isokinetic contractions at an angular velocity of 180 degrees . s-1: elbow flexion and knee extension series, separated by 3 h. The percentage of slow twitch fibers was similar in the biceps brachii (43.9%) and the vastus lateralis (43.3%). The fast twitch/slow twitch fiber area ratio was significantly higher in the more highly trained biceps brachii due to larger FT fibers. No relationship was found between fiber type composition and baseline peak torques or decline in peak torque due to the fatigue regimens. Baseline peak torque correlated with initial strength level, body weight, and limb girth. The results suggested that for these paddlers muscle strength and the decline in strength induced by repetitive isokinetic contractions were more dependent on characteristics of body size than on fiber type composition.

PMID: 7199455, UI: 82138752

Eclache J-P, Benezit C, Goetchy A : Étude de différents facteurs biomécaniques et de leur influence sur l'efficacité de la propulsion en canoë-kayak. Bull Ass. Sport Biol 1985;4.
Gulch RW, Fuchs P, Geist A, Eisold M, Heitkamp HC : Eccentric and posteccentric contractile behaviour of skeletal muscle: a comparative study in frog single fibres and in humans. Eur J Appl Physiol 1991;63(5):323-329

Institute of Physiology II, University of Tubingen, Federal Republic of Germany.

Eccentric and posteccentric force behaviour in human skeletal muscle and in isolated frog muscle fibres was studied by imposing stretch-and-hold loading conditions during contractions with maximal voluntary effort or under tetanic stimulation in the isolated preparations. The investigations on human muscle were made on the forearm flexors of a group of kayak racers (n = 16; age: 17-22 years) and of schoolgirls (n = 15; age: 17-18 years) with both groups participating in a strength-training programme over 4 (kayak racers) or 3 (girls) months. Half of the training regime consisted of eccentric elements. In the isolated muscle fibres, it could be shown that in the posteccentric hold phase the enhanced force decayed exponentially to the original isometric value with a mean time-constant of 0.35 s (10 degrees C) and of 0.23 (20 degrees C). In the forearm flexor of human subjects similar results were obtained not only qualitatively but even quantitatively (time constant of posteccentric force decay: 0.25-0.37 s). Strength training in both groups did not lead to an enhancement in maximal isometric force alone [mean increase in force 17 (SD 10)%], a well-known and generally accepted fact, but also to a parallel shift in eccentric [21 (SD 10)%] and posteccentric force level. The close similarity between the findings in isolated muscle fibres and in human muscle in situ suggests that the eccentric and posteccentric behaviour must be primarily ascribed to the contractile properties of the muscle fibres themselves. A three-element muscle model with variable visco-elastic properties would appear to be most suitable for simulating the experimental findings. (NDLW : où l'on prend les kayakistes pour des grenouilles…)

MEDLINE - PMID: 1773807, UI: 92128483

Jackson PS : Performance prediction for Olympic kayaks. J Sports Sci (ENGLAND) Jun 1995 13 (3) p 239-45

Department of Mechanical Engineering, University of Auckland, New Zealand. ISSN: 0264-0414 Language: ENGLISH. Document Type : JOURNAL ARTICLE. Journal Announcement: 9601

Subfile: INDEX MEDICUS

This paper sets out the effects of the various factors which determine the speed of racing kayaks and canoes, with the aim of identifying the areas most likely to lead to improvements. The friction, wave and aerodynamic component of hull drag are first described in terms of the hull parameters, in order to provide accurate predictions of propulsive power as a function of hull speed.The generation of thrust by paddling is described via the mechanics of vortex ring wakes, in order to determine the propulsive efficiency in terms of the parameters describing the blade and stroke. Equating the thrust and drag then leads to reliable estimates of the mechanical power actually delivered by a canoeist. The earlier analysis then leads to a predictive model for hull speed in terms of all the parameters describing the hull and blade performance. This is used to determine the sensitivity of hull speed to small changes in each parameter, enabling the most important factors to be identified. The paper concludes with a discussion of the various improvements to kayaks that have actually appeared in recent years, and uses the earlier analysis to explain and predict the resulting speed changes.

Tags: Human . Descriptors: *Biophysics; *Sports--Physiology--PH; Models, Theoretical; Task Performance and Analysis.

LIOW, D. K., and W. G. HOPKINS. Velocity Specificity of Weight Training for Kayak Sprint Performance. Med. Sci. Sports Exerc.,
Vol. 35, No. 7, pp. 1232–1237, 2003.
Sport, Fitness and Recreation Department, Wellington Institute of Technology, Lower Hutt, NEW ZEALAND; and Sport
and Recreation, Auckland University of Technology, Auckland, NEW ZEALAND
ABSTRACT :
Purpose: Athletes often use weight training to prepare for sprint events, but the effectiveness
of different types of weight training for sprinting is unclear. We have therefore investigated the effect of slow and explosive weight
training on kayak sprint performance. Methods: Twenty-seven male and 11 female experienced sprint kayakers were randomized to
slow weight training, explosive weight training, or control (usual training) groups. Weight training consisted of two sessions per week
for 6 wk; in each session the athletes performed 3–4 sets of two sport-specific exercises with a load of 80% 1-repetition-maximum.
The two training programs differed only in the time taken to complete the concentric phase of the exercises: slow, 1.7 s; explosive,
0.85 s. To determine the effects of training on sprint acceleration and speed maintenance, the athletes performed 15-m kayaking
sprints pre- and posttraining; an electronic timing system provided sprint times at 3.75-, 7.5-, and 15-m marks. Results: Relative to
control, both types of weight training substantially improved strength and sprint performance. The improvements in mean sprint time
over 15 m in each group were: slow, 3.4%; explosive, 2.3%; control, 0.2% (90% confidence limits for pairwise differences, ~1.4%).
Over the first 3.75 m, the improvements were: slow, 7.1%; explosive, 3.2%; control, 1.4% (~2.6%). Over the last 7.5 m, the
improvements were: slow, 2.1%; explosive, 3.0%; control, 0.8% (~1.9%). Conclusions: Slow weight training is likely to be more
effective than explosive training for improving the acceleration phase of sprinting, when force is high throughout the length of the
stroke. Explosive weight training may be more effective in speed maintenance, when forces are developed rapidly over a short period
at the start of the stroke. Key Words: ONE REPETITION-MAXIMUM, ACCELERATION, ATHLETE, EXPLOSIVE, RESISTANCE,
SPEED, STRENGTH
Mann RV, Kearney JT : A biomechanical analysis of the Olympic-style flatwater kayak stroke. Med Sci Sports Exerc 1980;12(3):183-188

To investigate the biomechanics of flatwater kayaking, the technique of nine Olympic caliber K-1 paddlers was analyzed using cinematographic and computer procedures. Results indicated that, during paddle-water contact, the horizontal arm action was one of push-then-pull with the push coming from the arm farthest from the water (thrust segments) followed by the pull coming from the arm closest to the water (draw segments). During this action, the center of paddle rotation shifted up the paddle shaft as the stroke progressed, which increased the time the paddle was in the power phase of the stroke. The horizontal movement patterns of the individual segments indicated that the push was accomplished by an integrated movement of the thrust wrist and elbow, with minimal shoulder involvement. Subsequently, the pull was accomplished by an integrated movement of the draw wrist, elbow, shoulder, as well as the thrust shoulder. During the latter stages of water contact, since the performers were unable to generate additional useful power, the paddle was rapidly withdrawn to avoid dragging. Subject stability in the frontal plane was maintained by shifting the body mass toward the water contact side at paddle entry and away from it at exit. This action opposed the vertical forces produced as a by-product of the stroke. The final outcome of this stroke technique was the maintenance of the body center of gravity velocity while the boat oscillated under the performer.

MEDLINE - PMID: 7402054, UI: 80253976

Plagenhoef S : Biomechanical analysis of Olympic flatwater kayaking and canoeing. Res Q 1979 Oct;50(3):443-459

MEDLINE - PMID: 545532, UI: 80191151

TARABEUX P : Étude biomécanique d'un geste sportif "l'appel en kayak". Thèse doct médecine 1985; Univ. Rennes, 60 p.