Butterfly is the most recently developed of the four main competitive swim strokes and is a strenuous yet powerful method of swimming. Because it is so physically demanding, it is not commonly seen amongst casual recreational swimmers. However, it does provide fitness benefits not offered by the other strokes, so arguably, Butterfly is undervalued by the average swimmer. Butterfly is instantly recognisable by the wide arm swing over the water. Under the water, the arms pull simultaneously in a movement pattern similar to front crawl, so for beginners, thinking of butterfly as a “double front crawl” can be a helpful starting point. In Butterfly, the legs kick downwards in a similar movement to a front crawl kick, but like the arms, a Butterfly kick utilises both legs simultaneously. This double leg kick causes the body to “undulate” or dive like a dolphin, which is another characteristic of the stroke. The Butterfly kick on its own is often referred to as a “dolphin kick” and some people separate this from the Butterfly entirely to call it the “Dolphin” stroke.

What is Butterfly used for?

Butterfly is primarily a competitive swimming stroke and because the propulsive action utilises both left and right sides of the body simultaneously it is a naturally fast and powerful stroke. For recreational swimmers, Butterfly offers an opportunity to improve shoulder and spinal flexibility as well as upper body and core muscle development. For people who have limited time available to swim, Butterfly can provide a high intensity workout, building strength quickly compared to Front Crawl. Because a racing style of Butterfly is so strenuous, competition distances have traditionally been shorter than those swum on other strokes, however more recently, a recreational adaptation of Butterfly has been used by amateur swimmers for long distance events and World Record attempts. The dolphin kick is arguably the fastest method of travelling under water, which is why it is incorporated into racing turns (tumble turns and touch-turns) and under water races.


Skills that help to improve Butterfly:

Development of Butterfly from Beginner to Advanced:


Young children are usually introduced to a Butterfly kick by pretending to swim like a mermaid, whale or dolphin, however swimmers should already be confident and happy to swim with the face in the water before starting Butterfly. The reason for this is that swimming Butterfly with the head up can put unnecessary strain on the spine and inhibits the development of an effective stroke. Compared to beginner adults, young children usually have more spinal flexibility and can more easily develop a strong undulating body roll as they kick.  Building good foundations with a strong kick and good body roll will make it easier to introduce the arm action later on.


A double arm pull (or double front crawl) can be a good starting point for the arm movement, but swimmers will find the arm action difficult or tiring until they have worked out the timing of arm movements compared to the body roll. Trying to lift the arms out of the water when the body is on an upward roll feels awkward and exhausting. The arms sweep more naturally over the water when the body is on a downwards dive but it takes practice for this to fall into place.


As with all swim strokes, Butterfly can be refined and adapted to suit the swimmer’s individual needs. There are many aspects of the stroke that can be modified, including the number of kicks per arm cycle, the position of the hands on entry, how often to breathe and how deep to roll. There isn’t one single “perfect” way to swim Butterfly, but certain adaptations can help you to swim faster, whilst others help to make the stroke more comfortable for long distance or fitness swimming. It is up to the individual to determine their personal goals and to experiment with modifications to find out which ones work best for them. Asking a swim teacher or friend to observe and analyse your stroke, or videoing your swim (where permitted) can help you to spot areas worth adapting. Using a stopwatch to time your swim, or listening to your body to work out how you feel when swimming your chosen distance can help you determine which modifications are helping you towards your chosen goal. For children who wish to compete, it is important to work with a swim club to develop the right technique alongside a training development plan in order to have the best chance of progressing through competition.

Skill-specific Hazards for Butterfly:

Besides the general inherent dangers involved with water-based activities, swimming Butterfly has a few of its own specific risks:

  • Some swimmers notice neck pain or lower back pain when swimming Butterfly
  • For young children, those who are going through growth spurts and people who are hypermobile, a Butterfly arm action can put excessive strain on weak shoulder joints. Dislocation is possible.
  • Swimming under water (dolphin kick) for long periods of time can cause a swimmer to pass out unexpectedly, which can be dangerous if they are swimming without a buddy or supervising adult.
  • As a high intensity exercise, Butterfly can be potentially hazardous for people with heart conditions
  • If a swimmer tires quickly and is out of their depth and/or in open water, they may be in danger unless they are able to utilise survival strategies (e.g. floating on the back or switching to a less strenuous stroke in order to swim to a point of safety)

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