The subjects for this study were swimmers at the 1991 Perth World Championships. Trends in body factors and some arm features were reported.
The elbow angle at the middle of the pull had the greatest effect on propelling force. Higher forces in the latter stages of the pull were associated with greater elbow bend (between 100 and 90 degrees) in the insweep phase. The straighter the arm the longer the pull pattern, the slower the turnover rate, the smaller the force at the finish, and the smaller the resultant force. The arm should not straighten at the finish.
Higher and more effective forces were also associated with greater amounts of body roll. The angle of roll should be in excess of 30 degrees. A large amount of body roll contributes to a longer stroke and greater propulsion. Swimmers should be encouraged to roll the body and never be instructed to "keep the shoulders flat."
[The position of the effective arm pull placed the center of the pushing surface (just above the wrist) directly under the inside of the pulling shoulder.]
When compared to distance swimmers, sprinters had a deeper pulling pattern and displayed a greater knee angle to allow a bigger and harder kick. They also had a higher longitudinal trunk angle and less body roll at the catch. These differences were most likely due to the recruitment of extra muscles to stabilize the torso so that extra force could be applied. The larger kick balances the more forceful pull and may marginally add to propulsion. The flatter cross-sectional body position may have accommodated the higher degree of hydroplaning that resulted from the extra speed.
Implications. The coaching factors for distance swimming are: i) encourage body roll to position the shoulder and back to be able to exert force on the arm; ii) promote bending the arm to almost 90 degrees; iii) position the arm under the pulling shoulder side of the body while the elbow remains outside of the body's alignment, and iv) emphasize streamlining, particularly a flat body position in the longitudinal plane.
For sprint swimming the above features should also be stressed but with less magnitude. The production of force is what is of major importance in sprinting whereas conservation of energy while maximizing propelling efficiency and effectiveness is important in distance stroking.
The undulating body movement in butterfly is often exaggerated to a detrimental level. Some wave action is necessary and desirable but it should not be of such a magnitude as to destroy streamlined characteristics of the body posture. Swimmers who swim flat are able to extend their elbows more at the finish (the time when the swimmer is going fastest). The vertical range of body movement is 40 degrees for 200 m swimmers and 30 degrees for sprinters.
[The maximum amount of undulation has the following characteristics:
Sprint butterfly was found to be different to 200 m butterfly. Sprinters: i) had a lower body angle (they undulated less); ii) had a flatter body angle at entry (more streamlined); and iii) were more efficient at the finish.
Implications. Distance butterfly is the weakest stroke internationally for both males and females. It would seem that paying attention to the following characteristics of the body position will promote better butterfly swimming:
The highest propelling efficiencies were found in swimmers who had the shallowest shoulder depth during the insweep. The depth is related to the position of the hips. [There is a tendency in many breaststrokers to exaggerate the shoulder lift beyond a facilitatory position. That extra emphasis sinks the hips to produce an inefficient rocking action in the body where the shoulders go up and the hips go down and vice versa. A rocking action is of no benefit and may slow the swimmer. There needs to be some wave action down the body of the modern breaststroker, but a wave is not a rocking movement. The hips should move up and down partly in time with the shoulders. The teaching point for this is that an emphasis on making body sections go up and down is detrimental to swimming speed. A better emphasis is to make the body parts go forward, and as a consequence, the shoulders and hips will be lowered but hopefully, no more than is necessary.]
While breathing and recovering, the body should be lunged directly forward. All these actions should occur without any hesitation and should be as fast as possible.
On the outsweep, it is desirable to have a slight elbow bend. Straight arms do not produce the same amount of force as do arms that are bent at an angle of about 160 degrees.
Sprinters, when compared to 200 m swimmers, were found to have the following characteristics:
The great improvements in breaststroke swimming over the past decade have come from better streamlining in all phases of the stroke.
A very significant statement was made: Keep the head down going back into the water. Previous research has shown that the resistance from the water doubles with the head up versus the head down (p. 110). This has particular relevance to NSW age group swimmers. It is inappropriate and inefficient to have the face profile looking forward, that is, swimming with a hyperextended neck. The face profile should be horizontal, that is, the swimmer should look at the pool bottom, during all phases of the stroke except breathing (when the head nods "yes" to clear the mouth above the bow wave). The lowering action of the head raises the hips to produce accentuated streamlining.
Rolling the body positions the arms for a better pull. A 45 degree roll to both sides, that is, a 90 degree rotation, was average for the swimmers observed. The same body position (as streamlined as possible), was observed for both sprinters and 200 m swimmers.
Sprinters, when compared to 200 m backstrokers, grabbed the water immediately and with a different hand orientation. The entry was made with a different hand pitch. The positioning of the hand is important for minimizing the time for readjustment and compressing the water. [Coaches spend too much time on the cosmetic aspects of the backstroke recovery, particularly the position of the hand; e.g., little finger leading and entering. The hand should enter the water at a 45 degree angle so that as the shoulders initiate their roll, the lower arm can immediately push backward.]
The position of the legs in backstroke is more advantageous for producing propulsion than in crawl stroke. The angle of the knee bend can be as much as 60 degrees thus, facilitating a large rearward force. If one were to attempt such a bend in crawl stroke, the foot would be well out of the water. That is why backstroke kicking does not employ the same mechanics as the crawl stroke kick.
The streamlining of the body is of paramount importance in all strokes. The body is the major contributor to resistance. Its shape creates passive resistance something which cannot be altered immediately. However, inefficient streamlining, unnecessary up and down or sideways movements, increases active resistance which slows the swimmer. The stabilization and orientation of the body is the central characteristic of good swimming. If the body is "out of position" it will not allow correct arm actions to occur which, in turn, result in less propelling efficiency. It is reasonable to assert that if the body position of a swimmer is not maximally streamlined, the swimmer will not be able to swim fast.
In the two symmetrical strokes, the body should be as streamlined as possible but it has to move to create a fast propulsive wave action. That action is not necessarily big. An exaggeration of the wave action segments will actually slow the cycle time to the point of not contributing to the force and even creating unnecessary resistance. Because a wave action is beneficial it does not necessarily follow that a bigger action is more beneficial. It would be more prudent for a coach to minimize the wave action, for at least then, the swimmer will be streamlined.
Return to Table of Contents for ICAR 1991-92 Report.