Why a higher stroke rate is not necessarily a better one

The time to perform a lap consists of several components. You can calculate lap time using following formula:

lap time forumla
Figure: the laptime breakdown.

In the previous blogposts, we discussed stroke rate and stroke length individually. Today we will have a closer look at swim time and stroke efficiency, which consists of stroke rate and stroke count together. In order to have a shorter swimming time, speed is the parameter you should focus on and train to optimize. When looking at swimming speed following formula is in order:

Swimming Speed Formula

Figure: the laptime breakdown.

Stroke rate and stroke length are intertwined​

The first important thing to understand when training your swim time is that you need to improve both stroke count (by improving stroke length) and stroke rate to swim a faster time. You would think that just increasing both maximally would render a faster swim speed, but this is not true. The reason for this is that both parameters don’t exist independent from one another. During a swim stroke length and stroke rate influence each other and you should thus focus on getting both parameters to their full potential.

Increase swimming speed focusing on both parameters​

Stroke rate and stroke length are intertwined, therefore, focusing on both parameters in the right way will result in an increased swimming speed. The graphs below show the relation between stroke rate, distance per stroke and speed. When increasing stroke rate your distance per stroke will gradually increase. However, from a certain level your distance per stroke will deteriorate again. This is because, from a certain point while increasing your stroke rate and speed, your arm movements will start to go from long and efficient, to short and inefficient. This is the turning point from which your speed will start to. The reason being is that because of the short and uncontrolled arm strokes you make, your stroke will start to ‘slip’ through the water, losing grip. By losing grip your stroke length decreases gradually. As stroke length and stroke rate need to be multiplied in order to get your swimming speed, from a certain point speed will start to decrease as slipping gets worse.

Velocity
Figure: The relation between stroke rate, distance per stroke and speed.
Figure: the swimming economy model.

A easy comparison for what happens is running. While running your legs take big steps. When you start to run faster, your legs need to move quicker. They are able to do so until a certain point when your legs can’t make such big steps while going so fast. Easily said your legs can’t keep up with the running speed anymore. From this point you start taking smaller steps again, resulting in gradually running slower. The same thing happens with swimming.

Stroke Index


As mentioned in our blog about stroke rate, it is important, especially for younger swimmers, to focus on stroke length, as this is an aspect of your stroke that should deteriorate as little as possible during a race. In order to achieve a faster swimming speed, it is thus key to maintain a good stroke length for an increasing stroke rate. This will improve your swimming speed as your optimum combination of stroke rate and stroke length (= your stroke efficiency) will shift to a faster swimming speed.​

Parameters that measure efficiency​

Following are some parameters that measure efficiency​. The first formula is the stroke index:

SI
Figure: the stroke index formula.

Stroke index will favor a higher distance per stroke at the same stroke rate. This means that when you increase distance per stroke the stroke index will increase twice as fast compared to when you increase your stroke rate. This is a choice of using this specific parameter. Another usable formula for stroke efficiency is SWOLF:

Figure: Calculating your SWOLF score.

We want to measure stroke efficiency during swimming, so we remove the turn time or underwater time from the derived formula to get swim time:

Figure: How to measure stroke efficiency during swimming?

Even though you can use SWOLF or stroke index to measure your stroke efficiency, it is your final swimming speed that really shows how efficient you are. How you reach this final speed does not matter. It is thus, important to note that stroke index and SWOLF are just indicators invented to give an idea of stroke efficiency. Stroke rate and stroke length are the basis for both of these parameters. These are still the two important basic working point for a swimmer to focus on when improving their efficiency. Improving stroke index or SWOLF should never be the sole focus of a workout plan as the optimal combination of a certain stroke rate with a specific stroke length is individual.

Take home: don’t focus on one parameter.

When improving stroke efficiency it is important to take into account that stroke rate and stroke count can not stand on their own. You should always focus on both parameters because they influence one another. There are various formulas that help you measure stroke efficiency. Though these offer help when improving stroke efficiency, these formulas should not be your sole focus. Stroke rate and stroke count are the two main elements of stroke efficiency and remain the most important focus. By improving both stroke rate and stroke count, your stroke efficiency will automatically improve as well.

Swimtraxx One measure your stroke index for every lap you swim. With this blog we have explained that this parameter on its own will not make you a better swimmer. Focus on the combination of your stroke rate and stroke length in order to increase your swimming speed. Swimtraxx One also measures stroke rate and stroke length in real-time. This gives coaches and swimmers the opportunity to interpret their swimming efficiency correctly without having to collect the data yourself.

Thank you for your interest in this blogpost. Be sure to keep an eye out for new blogposts as we will regularly be adding swim specific content. We have some tips and tricks scheduled as well. If you wish to stay updated about our news, subscribe to our newsletter below and never miss a thing.

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