Deciding what stroke rate you should use in freestyle is not necessarily easy. There are two very different techniques commonly used in freestyle: hip-driven and shoulder-driven. The difference between the two is largely determined by the time the hand is held out in front (lift phase) before initiating the propulsive phase of the pull. That time, in turn, influences your stroke rate. There is also a hybrid freestyle technique that many elite swimmers use (Michael Phelps, Ryan Lochte, Katie Ledecky) that involves using one arm of shoulder-driven and one arm of hip-driven.
There are advantages and disadvantages of each technique, so before deciding which one works best, you should learn about each and experiment with both of them.
Hip-driven vs. shoulder-driven
Hip-driven freestyle generates more power for each pull, if done correctly. The additional time with your hand held out in front enables you to rotate your hips further, generating more kinetic energy during the counter-rotation, while one arm is pulling. This additional energy augments the effect of the pulling force, resulting in more distance per stroke. Another advantage is that fewer pulling strokes taken may decrease the amount of energy required to swim, or increase the efficiency of your swimming.
The disadvantages of this method are there are fewer propulsive forces from the pull, which, particularly without a strong kick, can lead to greater fluctuation of the body speed. The variance of body speed does not conform well to the law of inertia and, in open water, you can lose a lot of momentum, particularly in choppy/rough conditions.
In changing from hip-driven to shoulder-driven freestyle, the function of the hand and arm goes from a wing and a paddle to more of a propeller function. Now, RPM becomes as important as the shear power of each stroke. Shoulder-driven freestyle demands a higher stroke rate.
Typical stroke rates
For distances of over 400 meters, the stroke rates may range from the mid 50s to around 100 (strokes per minute). Although there is not clearly one stroke rate where the technique switches from hip-driven to shoulder-driven, we can safely call a stroke rate of 50–70 per minute (that means 25–35 right and 25–35 left arm strokes per minute) hip-driven and, for the most part, stroke rates of between 85–100 are considered shoulder-driven (some swimmers can swim with a very fast hybrid technique at these rates). The rates between 70 and 85 are either hybrid or in the gray area of slow shoulder-driven or fast hip-driven.
With either technique, the time spent in the propulsive phase (the time the hand is moving backward creating propulsion) is around .35 seconds. Including both hands, that makes .7 seconds of propulsion time per stroke cycle. If the stroke rate is 60, that means the cycle time (hand entry to hand entry) is 2 seconds (60/30). If the hands are in propulsion for only .7 of that 2 seconds, that is 35% of the time. The rest of the time (65%), the hand is either in lift phase or recovery phase, but it is not moving the body forward. That is a lot of “down” time or dead time, which in an open-water swim (especially in rougher conditions) you will pay for dearly.
Besides the hands, the only other source we have to create propulsion is with our feet. Because of the extraordinary amount of “down” time in the pulling motion of hip-driven freestyle, to use this technique more effectively, you need to have a steady six-beat kick. The steady propulsion from the kick will help maintain a more constant speed.
In shoulder-driven freestyle, say with a stroke rate of 100, the cycle time is 60/50 or 1.2 seconds. The propulsive phase is still .7 seconds, which is now 58% of the cycle time, with the other 42% considered “down” time, which is better…but not perfect. Ideally, to use shoulder-driven freestyle, we need to grow a third arm, so that one hand is in the propulsive phase at all times. (That is why you never see propellers on boats with less than three blades.)
How does the kick come into play?
While it may seem logical to assume that without a strong kick, a swimmer should adopt the shoulder-driven freestyle technique, it doesn’t work well for everyone in that category (which includes most triathletes). Some cannot handle the aerobic requirements of the higher stroke rate and end up exhausting themselves trying to keep it up. The amount of training and fitness level of the athlete can therefore influence the decision of which technique to use.
The best advice I can give is to learn how to swim freestyle using both techniques, even hybrid if you want to. Then do sets using all techniques, testing your workout times and heart rates with each one, to see which works better for you. If shoulder-driven freestyle seems to be faster, but tires you out too much, you may simply need to train more to reach your goals. Sustaining a higher stroke rate in freestyle requires time and commitment to achieve. It’s also well worth using a tempo trainer in training to help you get used to different stroke rates.
Whichever technique works best, the fundamentals of reducing frontal drag, maximizing propulsion and conforming to the law of inertia must also be considered important strategies for your continued stroke rate improvement.