Have you ever noticed that some swimmers have a long, smooth stroke while others swim equally as well with a short, fast turnover? Perhaps you’ve seen this and have wondered what style is best to become fast and efficient.
Different body types can have a huge impact on stroke technique, with one particular aspect being the length of your arms. To analyse arm length in relation to height we use a measurement called the “ape index,” a term taken from the rock climbing world.
How your ape index affects your swimming
If you have shorter arms you won’t be able to travel as far with every stroke.
Many swimmers are told they need a very long stroke to be efficient, but if you have shorter arms, that style is pretty much impossible. You need to swim with a higher stroke rate and a lot more rhythm. This is a little like spinning a smaller gear on the bike: Each stroke takes less effort but you take more of them.
While having shorter arms means you need a faster stroke cadence, the opposite isn’t true. If you have long arms, you don’t need to swim with a long stroke—you actually have the option of using either style. Many swimmers with positive ape indexes do adopt a long stroke very effectively—in the pool it certainly can be very efficient. However, many top triathletes have long arms but choose to swim with a shorter, faster stroke to help them punch through waves and chop in open water.
Another good reason to swim with a shorter, faster stroke is if it just feels right to you. Many Olympic swimmers with long arms (such as Janet Evans and Laure Manaudou) have used this style to great success. The analogy with cycling also applies: Lance Armstrong is famous for spinning a smaller gear than Jan Ullrich, who preferred a bigger gear and a slower cadence. Two great riders, each using a style that best suited them.
How to measure your ape index
Take off your shoes and stand next to a wall or post. Stretch out so the fingertips of one hand just touch the ground and the top hand stretches upward as high as it can go. When you’re fully stretched out, keep your top fingertips in place on the wall and stand up beside them. Note the difference in your arm span and height and gauge it in inches.
If your arms are 2 inches longer than your height, you have an ape index of +2. If your arms are 3 inches shorter, your ape index is -3. The average ape index is around zero, with a slight bias between the sexes: On average, men have slightly longer arms relative to their height than women.