How Biomechanics Influences Olympic Rowing Essay.
Rowing is a sport in where athletes compete against each other in specially designed boats on rivers, lakes or oceans depending on the type of race and the discipline. Different types of race include endurance, time-trial, side by side Olympic rowing and many others. Rowing can take one of two formats * Sweep rowing – each rower has one oar, held with both hands, commonly done in pairs, fours or eights. * Sculling – each rower has two oars, one in each hand, commonly done as a single, pair or fours With reference to biomechanics, rowing has two main areas in which biomechanics can be applied to further understand and enhance performance.
These are Technique and Equipment. Technique
* Of the stroke The most important movement in rowing is the rowing stroke. Both sweep rowing and sculling use very similar stroke styles with the slight differences. The rowing stroke makes use of limbs acting as levers to generate force therefore a biomechanical understanding of how to use the limbs to generate a greater force will improve performance.
* Of the movement
Rowing is a cyclic (intermittent) form of propulsion. Therefore a steady state system of motion is required to maintain a constant propulsion. In order to do this biomechanics can be applied to improve the system without accelerating or decelerating the system. Equipment
Biomechanics can be applied to examine and analyze equipment in terms of drag forces, weight and buoyancies issues to give optimal performance.
Specific topic – Technique Rowing performance is majorly influenced by factors that affect overall boat speed or in biomechanical terms average velocity (Smith & Loschner, 2002). Rowing technique encompasses both the stroke and the cyclic movement of the stroke. The rowing stroke can be analyzed by breaking it down into two phases, drive and recovery. Drive
This is the phase from the catch to the extraction. * As soon as the oar blade is securely placed in the water at the catch, the rower begins to lever the boat past the blade by straightening the legs while the body remains leaned forward and the arms straight. This is called the leg drive. * After the rower completes the leg drive, the rower finishes opening up his or her back towards the bow while at the same time using his or her arms to pull the oar(s) to his chest. This is called the draw. * The rower pushes the oar handle down so the oar blade comes out of the water. * Just as the oar blade is being removed from the water, the rower rotates the oar handle 90 degrees so that the blade is again parallel to the water. This action is referred to as feathering. Recovery
This is the phase from the extraction to the catch. * The rower extends the arms fully forward (toward the stern) pushing the oar away from his or her body while, at the same time, keeping the oar at a constant height with his or her legs straight, and torso leaning back. * The rower leans the body forward to around 30 degrees past vertical, continuing to keep the oar level, not bending the knees and keeping the back straight. This stage of the recovery is sometimes referred to as “body prep”. * The rower bends the legs, bringing the sliding seat forward (i.e. toward the stern) on its rollers, while the oar remains level. * While continuing to slide the seat forward, the rower rotates the oar handle(s), causing the face of the blade to be perpendicular to the water. This is called squaring or rolling up the blade. This, depending on the rower’s technique, begins approximately when the oar handle(s) pass over the ankles. * When the rower reaches the sternmost point of the slide, the end of the recovery, and the shins are vertical, the blade is quickly and smoothly dropped into the water by a slight lifting of the hands. This is called the catch.
From these phases we can begin draw both kinetic and kinematic variables that may improve performance. In order to produce boat velocity, Propulsive power generated from the rowing stroke must overcome drag forces acting on the boat,oars and rower in both the air and water. Variables the rower can manipulate are the scale and timing of the forces on the oar handles, seat and strecher and co-ordination of body segments (Smith & Loschner,2002). Soper (2004) found that boat velocity during single sculling is at its highest when the rower is in the recovery phase of the stroke. They attribute this to a number of factors such as a delay in the ability to overcome water resistance and inertia of the system together with the relative velocity of the oars and the boat.
This would suggest that boat velocity would increase if deceleration at the beginning of the catch could be removed. Another factor that directly influences boat velocity is velocity of the stroke (for more than one rower it would be an average of all the rowers strokes). Stroke velocity can be attained by multiplying the stroke length by the stroke rate. McBride (as cited in Soper, 2004) states that there is a linear correlation between increasing stroke rate and increasing boat velocity. An increase in stroke rate enables a greater force production during the stroke applied earlier in the drive phase (Roth et al, as cited in Soper, 2004). However Soper (2004) identifies that due to the cyclic nature of the rowing stroke, temporal patterns will emerge that also influence average boat velocity.
These intra-stroke fluctuations have a negative effect on boat velocity and increase as stroke rate increases, thus requiring more force production during the drive phase to continually increase velocity of the boat (Martin & Bernfield, 1980). Therefore eliminating these fluctuations would increase boat velocity more efficiently due to the increasing stroke rate. Stroke length is the total length the boat travels during a full cycle, however it is stroke drive length (when the blades are submerged) that is the primary contributor to overall boat velocity. Sanderson & Martindale (as cited in Soper, 2004) found that force production is largely ineffective at the catch at finish positions of the stroke.
To maintain an effective and efficient stroke cycle in a cyclic rhythm it is important to understand the kinetics and kinematics involved. Previous rowing research has typically been done in 2D but some on water video analysis has been attempted. Bompa (as cited in soper, 2004) discusses the effect of knee and elbow joint angles in relation to force production. He found that a close packed position during the catch (increased knee flexion position) allowed for force production predominantly from leg extension. A moderate catch position was said to be most efficient while a minimally packed catch position (decreased knee flexion) allowed for increased stroke length but a reduction in the range of knee extension. In regard to elbow joint kinematics, Bompa observed that rowers (n = 11) who kept their elbows tucked in tight to the trunk as opposed to pointing out produced 131.1N (30.1%, p < 0.05) more force. Also rowers who began the drive phase with elbow extension (180°) produced 38.4N or 6.3% greater force than those with flexed elbows (150°).
The drive phase of the stroke can also be analyzed in terms of segmental co-ordination in order to improve performance. Nelson and Widule (as cited in Soper, 2004) found that in novice rowers, there was a delay in the peak angular velocity between the knees and trunk. This resulted in a reduced sum of both the knee and trunk velocities combined. These findings were concurrent with Hume and Soper (as cited in Soper, 2004) who discovered a clear sequencial movement pattern in elite rowers eliminating the delay in peak velocity. This sequencial movement technique is known as the Rosenberg style in reference to the ex US national coach who was the first person to find that sequencial movement of the legs followed by lower trunk, mid trunk, arms and wrists will enhance boat acceleration due to maximal total force output. Electromyography of the muscles during the stroke showed synchronious recruitment of important major leg muscles essential to the drive phase, while peak force activity levels were reached at peak handle force and mid drive (knee angle 90°)