“Usain can do the 100m in 41 strides. I take 44. But I have a better stride frequency: 4.96 compared to 4.65. To beat him, I need to maintain my frequency and improve my stride length.” Dwain Chambers (2008)
The above quote was by Dwain Chambers as part of his “Project Bolt”, his unsuccessful attempt to beat Usain Bolt at the 2009 World Championships. It deals with the two components of speed as illustrated by Hunter (2004)- that is that speed is product of stride length (SL) and stride frequency (SF). On the face of it, DC’s comments make sense- if he could maintain his SF and improve his SL, he would indeed get faster. However, a negative interaction between SF and SL has been found; as one increases, the other usually decreases to an extent. So, if DC elongated his strides to cover the 100m in 41 strides, he might find his SF would decrease, possibly with no improvement in speed.
But does either SL or SF influence max velocity to a greater extent than the other? Paruzel-Dyja (2006) looked at 100m runners at the 2003 World Champs in Paris. He found that in males, there was a significant correlation between results and SL (i.e. faster athletes had a greater SL). In females, there was a significant correlation between results and SF. These results were mirrored in studies by Letzelter (1999) on studies at the 1997 and 1999 WC. Korhonen (2003) and Hamilton (1993) found that Masters athletes get slower with ages because of differences in SL as opposed to SF.
On an individual basis, Hoffman (1971) found that individual athletes ran their fastest times when their SF was highest, assuming their SL stayed close to constant. Male athletes have a longer SL than females, which may contribute to a greater running speed.
In conclusion, we can see that both SL and SF both affect maximum running velocity. Other factors that may affect both SL and SF include ground reaction force (Weyand 2000), leg length (Paruzel-Dyja 2006), contact time (Bushnells & Hunter 2007), hip angle (Kivi 1999), and fibre type (Mero 1985).