Category Archives: Stroke
By Genadijus Sokolovas, Ph.D. Senior Physiologist
Global Sport Technology, Inc.
A new Swim Power test was developed by the Global Sport Technology, Inc to analyze the changes of swimming velocity (m/sec), force (kg), acceleration (m/sec/sec), and power (kg x m/sec). All these parameters are recorded instantaneously 60 times per second (60 Hz) at specific points in the swim stroke. Testing results are synchronized with video software to superimpose them with underwater video in real time and then recorded later on a DVD for easy review.
The Swim Power test quantifies every phase of individual stroke. Swimmers have different strengths and weaknesses, which can be identified using the Swim Power test. Some swimmers may have very strong beginning of stroke, while others may be stronger in the middle or at the end of the stroke. There are differences between left and right arm stroke, between left and right leg kick, timing between various phases of the stroke, etc. There is no “perfect stroke.” Even elite level swimmers have plenty of room to improve their swimming technique. By identifying individual strengths and weaknesses using the new Swim Power test, we can develop drills and swimming sets to improve everybody’s swimming technique.
Testing Protocols for Swimmers Variety of testing protocols may be used testing the Swim Power. Depending on individual goals, swimmers may be tested in full body swim, pulling or kicking only, underwater kicking after turns and dives, swimming fully rested and under fatigue, and many other positions. Coaches and athletes can even test advantages and shortages of different swimming techniques. Swim Power test will reveal strengths and weaknesses of every type of swimming technique. The standard Swim Power testing protocol for freestyle and backstroke includes three 25 meters efforts at race pace in various positions unique to the specific stroke analyzed:
- Pull with buoy (Figure 1)
- Kick (Figure 2)
- Swim (Figure 3)
Figure 1. Pull position.
Figure 2. Kick position.
Figure 3. Swim position.
The vertical green line in the middle of the graph indicates swimmer’s position on the video. Real time velocity and force parameters at every point of the swimming cycle are displayed below the graphs. Kicking is done with a kickboard for freestyle, butterfly, and breaststroke. Backstroke kicking is tested in streamline position without a kickboard. In addition to these kicking positions, underwater fly kick may be tested for flyers, backstrokers, and freestylers (Figure 4).
Figure 4. Underwater fly kick.
Analysis of Swim Power Testing Results
Analysis of testing results is based on changes of swimming velocity (force, acceleration, and power) during the swim cycle. Since every swimmer has different strengths and weaknesses, feedback includes individual recommendations/drills to improve swimming (or water polo) technique.
Every swim stroke has specific changes of swimming velocity. The largest changes of velocity in swimming cycle are for breaststroke and butterfly. Normally, larger changes of velocity in swimming cycle are related to higher energy expenditure. In fact, studies in exercise physiology (Sokolovas & Woodruff, 2004, etc.) proved that butterfly and breaststroke are the most energy demanding strokes. A typical velocity curve in breaststroke is presented in Figure 8.
Figure 8. Breaststroke velocity curve (digitizing).
Individual recommendations from the new Swim Power test are focused on:
- Reduction of time at slow phases of the stroke
- A smaller drop of swimming velocity at slow phases of the stroke
- Maintaining higher swimming velocity for a longer time at fast phases of the stroke
- Minimizing fluctuations of velocity during the swimming cycle
Recently we developed Swim Power software, which quantifies/digitizes changes of swimming velocity in every stroke. The software analyzes many different parameters, such as average of swimming velocity during the fastest and slowest phases of the swim cycle, changes of swimming velocity during the swim cycle, velocity at various points of the cycle, timing of various phases of swim cycle, and many others. For instance, digitizing of breaststroke (see Figure 8) includes calculation of average velocity at every point of the stroke (at A, B, C, D, and E), velocities at all phases (A-B, B-C, etc.), average percent increase/decrease in velocity (from A to B, B to C, etc.), average percent time for each phase (A-B, B-C, etc.), and some other parameters. The number of swim cycle parameters is between 24 and 32 depending on the complexity of swim stroke.
You can find more information about the Swim Power test at www.globsport.org.
March 28, 2011
News For SWIM PARENTS
Published by Guy Edson, American Swimming Coaches Association, 5101 NW 21 Ave., Suite 200, Fort Lauderdale FL 33309
The Nature of Stroke Work: Sometimes the Perception is That Not Enough Stroke Work Is Being Done
A sometimes concern among Moms and Dads is whether enough stroke work is being done. “All they do is swim. I don’t see any instruction at all,” is a typical refrain. The purpose of this short article is to explain what to expect from stroke work and to describe the different ways we coaches do stroke work and when we do it.
What to expect from stroke work: Do you remember teaching your children to tie their shoes? Some get it sooner, some get it later, some get it when you are not even watching. Each gets it in their own time regardless of your efforts. Same deal on stroke work. We hope to see immediate improvement but it is not always there. Patience is the key. Thorndike’s “laws” of learning come into play here: Is the child ready to learn? Does the child repeat the skill at the conscious level in order to move the skill from the conscious level to the automatic level? (Are they even operating at the conscious level during repeats?) With some children we notice a “delayed reaction” to teaching where they apparently make very little progress at the time and then some time later, sometimes even weeks later, magically get it. There is trial and error learning going on at the subconscious, level and it may take many repeats for things to suddenly click. So why do coaches allow swimmers to swim lap after lap with incorrect technique? Because, the hope is that a seed planted by the coach suddenly blossoms through trial and error learning after many repeats.
Where do those seeds come from? There are three basic types of stroke work. The most obvious is formal teaching where the lane or the workout group is stopped from aerobic or race pace swimming conditioning for 10 to 20 minutes and the coach explains a technique, uses a demonstrator, and then will have the athletes attempt the skill, usually one at a time with immediate feedback from the coach. This type of instruction is commonly used nearly every day with less advanced swimmers (novice), and less frequently with more advanced swimmers. Early in the season the coach may have the more advanced swimmers involved with formal teaching nearly every day as well.
A second form of stroke work is the stroke drill. Stroke drills are intended to isolate a part of the stroke so that the swimmer can focus on that particular skill. Stroke drills are often done as repeats on a low to moderate rest interval so that there is a conditioning effect as well.
The third form of stroke work is the most common – to some coaches it is the most important – and it is the most misunderstood and underappreciated by some observers (parents). This form of stroke work is the constant reminders coaches give to swimmers either verbally during the short rest periods between swims or visual cues demonstrated by the coach during the swims. The purpose is to move swimmers from an automatically wrong movement to the consciously correct movement; and if done enough, and given enough time, will effect a change. Some coaches are “always” doing stroke work of this type, even though it is not always easy to observe from the bleachers.
I meet with parent’s groups regularly and I like to do this little exercise with them: “Imagine a successful swimmer at whatever level you chose – state level, regional, national, international. Now, let’s list the factors that contribute to this swimmers success. Ready go.” When I do this exercise I get responses such as, “work ethic,” “discipline,” and “commitment” — these are factors relating to the psychology of the athlete. We usually get 8, 10, or maybe even 12 factors on the list before we get to…”technique.” I am not saying that technique is not important – it is – but every Olympic gold medalist has defects in their stroke. The pursuit of the impossibly perfect stroke is futile. Yes, stroke work IS important, but I am not sure it is the most important thing for advanced swimmers. When we observe a coach who doesn’t appear to be doing enough stroke work, step back and look at the larger picture. Is the child happy and improving? If so, then life is good.
(If not, then please see the March 14th issue on “How to Talk to Your Coach.”)
- Learning From the Best (swimmerjoe.com)