Swimming Straight (Path Linearity) and Drag in Swimming
1. Please introduce yourself to the readers (how you started in the profession, education, credentials, experience, etc.).
Hello, my name is Giorgio Gatta. I’m assistant professor at the Department for Life Quality Studies of the School of Pharmacy, Biotechnology and Sport Science of the University of Bologna.
My field of research is “Human movement analysis in aquatic environment”. We analyze different aspects and motor tasks, like gait analysis, running or walking in water, rehabilitation activities, sport activities, underwater activities, fitness activities, and more (for depending see to: http://scholar.google.it/citations?user=hxyTI5UAAAAJ&hl=it&oi=ao
… Specifically about swimming, our group has been studying biomechanics and energetic analysis in sport performance.
2. You recently published a couple studies on swimming. First, what made you interested in path linearity and what is it?
The study entitled “path linearity” is the analysis of the deviation from a straight course during the swimming’s race. We published two works to test some aspects that this problem creates from drag for the swimmer. The first was about a feasibility test while the second was much more complex because it was written using data collected during the Italian National championships.
Aim of this study was to evaluate path linearity and some related variables of elite swimmers, during a top-level front crawl competition of 400 m. Specific performance pattern were then identified.
3. What did this study look at?
The propulsive action of the limbs causes lateral fluctuations from the straight path. One of the most effective strategy to reduce drag is maintaining the body position as much hydrodynamic as possible during the propulsive action.
Strokes, voluntary adjustments, and breathings are key factors in this context. Some temporal windows were chosen according to the time needed to perform a ‘stroke’ (0.2-1.4 s) or a breath (1.4-2.5 s). A time greater than 2.5 s was thus assigned to the event ‘voluntary adjustments’ (i.e. any attempt of the swimmer to go back to the ideal trajectory that he has lost).
In terms of percentages, strokes, breathings, and voluntary adjustments contributed to lateral fluctuations, on average, by approximately 55%, 10%, and 35%, respectively
5. If a swimmer wanted to improve path linearity, what do you recommend?
Thus, coaches and athletes, working on stroke technique for propulsion and on voluntary adjustments for strategy purpose, should also pay attention to the relevant influences on path linearity as a side effect. For example Always changing side breathing, swimming short distances with closed eyes, changing the side of movement when you are in lane, etc.
6. What are your thoughts on circle swimming practice?
I think that new methods of training should be discovered and applied to the swimming practice, in order to better develop the best technique.
7.You have another study on frontal area in the four swimming strokes. What do we know about the differences in frontal drag between strokes?
We know that while in the breaststroke the swimmer opposes advancement of a larger area of the body, in other styles the frontal area is similar, because mainly determined by the physical structure of the swimmer. However, important differences can be made in the position that is held during the acceleration phases of the swim.
8. What did this study look at?
This study investigated the drag which is one of the most difficult parameter to measure in the water. We believe there is a relationship between the passive drag and active drag in the different styles of swimming and that there should be no big differences between drag of two swimmers of a good standard with a similar physical structure. The scientific literature has been in conflict over years in the attempt of finding the most correct method to measure the drag. When we will be able to provide coaches a method applicable and useful, swimming will make a significant step forward. Our goal was to bring a contribution to the debate.
The values of drag that we found in this work seem to confirm the right balance between driving forces and drag forces. In our laboratories we carried out comprehensive tests of functional evaluation on important international swimmers and sprinters of the Italian National team: these data can be very useful to support the work of coaches giving then a more “objective eye”.
10. What are some misconceptions about frontal drag in the different swimming strokes?
In recent years the importance of the position of the body in water has been much emphasized by several authors.. However, also the use of costumes rubber typically affect the position of the swimmers much more than you might think. The swimmer moves in an environment with a density so high that hydrodynamics must be enhanced at the same level of the aerodynamics in the formula one. For this reason each detail becomes very important. We have thus verified that not only the position of the head, but also the type of headset become very important. Without a depth study of each detail of hydrodynamics, swimmers would not be able to bebe competitive in different styles.
11. When a swimmer wants to reduce drag, where do you suggest they start?
From my experience I can suggest three specific areas where coaches and swimmers should be careful. With particular expedients on each specific area can trigger a reduction of about 2N to the value of K, that is the individual coefficient of drag, which includes a set of different factors. In males, this value is about 34/40 and can therefore oscillate more or less 6N. The first area is relative to the physical structure of the swimmer, and can swing when they changes diet or strength training. The second area concerns the posture in the water. Athletes often use positions that they feel “more comfortable” but we know that these position are very often less efficient. The third factor is the adopted technique used for the propulsive action and the breathing. Techniques the way to produce the more efficient oscillations of the body in the three reference axes: roll / pitch / yaw.
12. What research or projects are you currently working on or should we look from you in the future?
We keep studying swimming and several aspects related to this wonderful sport especially the kinematic analysis using inertial sensors. Inertial sensors will provide us with several evaluation factors that determine the performance.
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