Category Archives: research

A New Swim Power Test

A New Swim Power Test

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:

  1. Pull with buoy (Figure 1)
  2. Kick (Figure 2)
  3. 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:

  1. Reduction of time at slow phases of the stroke
  2. A smaller drop of swimming velocity at slow phases of the stroke
  3. Maintaining higher swimming velocity for a longer time at fast phases of the stroke
  4. 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


Speak Up!


A timeless debate…”Quality vs. Quantity”.

How much is too much? We want to know how your club/team trains…more yardage? Less Yardage? Looking for info for a research project.

Coach John Douglass (Assistant Coach; UW-Milwaukee Swimming and Diving) is doing a research project looking at relationships between training yardage and swimming success. If you think you can contribute to the data collection process, or have information to contribute, please contact John at