Sprint Performance: Perspectives on the importance of length and frequency

In my first post I made the case that we need to consider technique as well as force production in sprinting, and then in the second began to look at the relative importance of step length and step frequency in posing the question “metres or seconds; which is more important?” Here, I will expand on the some of the specific findings in the research.

When comparing across trained sprinters of different levels, studies have often shown that better athletes take longer steps (in terms of distance) when coming out of the blocks [1,2]. However, the exact cause and effect here is not clear, and training or directing athletes to increase step length in the first few metres won’t necessarily have the desired outcome of improving performance without addressing the underlying technique and force production.

Ryu Nagahara and colleagues in Japan recently found [3] that increases in step frequency in the first three steps (rather than the actual frequency values) are most closely linked to initial acceleration performance. From steps five to 15 they found that it was the increase in step length (again rather than the actual length itself) that related to improved acceleration. Other than this study, research is limited looking specifically at the acceleration and transition phases in trained sprinters.

By the time we get to maximum velocity findings are not so consistent, and the way in which studies have been designed has influenced whether they have said that step length or step frequency is most important to performance. My own research [4] has found that we need to compare athletes to themselves rather than taking a group approach, as some tend to run their fastest when they maximise their step length, and others when the maximise their step frequency. I plan to write a post expanding on that study here in the near future.

In previous discussions with elite sprint coaches, I have realised that they can sometimes be reluctant to directly cue step length or step frequency in their athletes for fear of causing over-striding or a rushed ground contact. My observations have also shown me that coaches can be very quick at picking up whether their athletes’ performance is most reliant on either step length or step frequency. My recently accepted paper to this year’s ISBS conference expands on these observations, so I will post here on that at the time of the conference.

Coaches make all of those observations about step length and frequency whilst also analysing how their athletes’ ability to create forces is influencing their performance. As applied biomechanists, we need to consider these things together, too, to fully understand performance; both effective force production and the observable movement patterns. As an aside, a recent blog post by Steve Magness [5] on the applied scientist — coach relationship was really insightful and thought provoking.

At the moment, the scientific literature cannot tell us how the observable movement patterns and force production combine to create optimum step length and step frequency in sprinters. My firm belief is that there is not a one size fits all model that works for all sprinters. What do you think? I would love to hear you thoughts on the relative importance of step length and step frequency. Also, please add a note to the blog if you feel there are any important papers I have missed out so far.

References
1. Bezodis, N. E., Salo, A. I. T., & Trewartha, G. (2015). Relationships between lower-limb kinematics and block phase performance in a cross section of sprinters. European Journal of Sport Science, 15(2), 118–124. doi: 10.1080/17461391.2014.928915
2. Slawinski, J., Bonnefoy, A., Leveque, J. M., Ontanon, G., Riquet, A., Dumas, R., & Cheze, L. (2010). Kinematic and kinetic comparisons of elite and well-trained sprinters during sprint start. Journal of Strength and Conditioning Research, 24(4), 896–905. doi: 10.1519/JSC.0b013e3181ad344
3. Nagahara, R., Naito, H., Morin, J. B., & Zushi, K. (2014). Association of Acceleration with Spatiotemporal Variables in Maximal Sprinting. International Journal of Sports Medicine, 35(9), 755–761. doi: 10.1055/s-0033–1363252
4. Salo, A.I.T., Bezodis, I.N., Batterham. A.M. & Kerwin D.G. (2011). Elite Sprinting: Are Athletes Individually Step Frequency or Step Length Reliant? Medicine and Science in Sports and Exercise, 43(6), 1055–1062. doi: 10.1249/MSS.0b013e318201f6f8.
5. Magness, S. (2015). http://www.scienceofrunning.com/2015/03/the-sub-2hr-marathon-why-coaches-and.html