Fast-twitch muscle for a fast start!

How much of start and turn performance in the pool is Nature, and how much is nurture?

Getting a good start is essential for good times in shorter-distance events. In sprinting events over a very short distance, an explosive start with great acceleration and good technical execution is even more important. In swimming events however, it’s not just explosive starts off the block that matter; each and every turn (one in a 100m race, three in a 200m race etc) requires an explosive kick off the pool wall – along with good execution.

Start and turn power

How trainable is explosive start and turning power, and how able are short-distance swimmers to maximize it for performance? Some brand new research suggests that start times (and to a lesser extent turn times) in sprint events are partly determined and limited by an athlete’s innate muscle fiber typology. This is highly relevant when you consider that around 12% of the overall performance time in these swim events is determined by starts and turns.

In this research, titled Muscle Fiber Typology and Its Association With Start and Turn Performance in Elite Swimmers, international and national competition racing performance was analyzed from 21 female and 25 male elite swimmers. The start, turn in, and turn out times were determined from each of the swimmers’ career-best performance times. A technique known as proton magnetic resonance spectroscopy was then used to determine the muscle concentration of a compound called carnosine in the calf muscles (gastrocnemius and soleus) in all of the swimmers. In short, fast-twitch explosive muscle fibers are much richer in carnosine than slower-twitch endurance fibers, so this technique can be used to identify what % of muscle fibers are fast twitch.

The findings

The results showed that the fastest start times in these swimmers were strongly correlated to highest levels of fast-twitch fibers, especially in the 100m event. In male swimmers, higher fast-twitch fiber levels were also correlated to faster turn times, suggesting a correlation between the two (although less strong than start times – presumably because more technique is required for efficient turns). It seems then that when it comes to fast start times, good reactions and a degree of technique is required but much of the performance attained in the start comes down to good genetics. The higher involvement of technique for fast turns means that while explosive strength is very important, this is something that swimmers can work on and significantly develop. For an in-depth discussion on what the research says about optimum turn technique (particularly the depth and length of the glide), readers are directed to this article.

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