I am surprised you guys think a fast stride frequency is the key to being a fast runner. I see plenty of slow runners (often females), who appear as if they are going a lot faster than they are because they clip along with a pretty quick, choppy turnover. But they are covering very little ground with those strides, and thus going nowhere. And guess what? I doubt much changes when they race. I've also seen some older folks move along slowly with a pretty decent turnover. But again, they have little flexibility or strength, so they can only cover a little ground with those strides, and again, they don't don't move very fast.
As Coe/Martin pointed out in their book many moons ago, as running speed increases more and more, stride rate and stride length both increase, but stride LENGTH increases a lot more. If you want to run really fast.... you need to increase your stride length. And doing strength exercises, flexibility work, jumping drills, and yes, practicing a longer more powerful stride sometimes will all move you in that direction.
And related to this idea of increased power being important (but not necessarily about stride length) is where I've been waiting to hear JK talk about -explosive strength training( he has more parts to come), because I've seen several studies showing that strength training improves running economy. And it makes sense, because as your legs become more powerful and neurally efficient, the energy it takes for one push off the ground with each stride becomes less, and thus you run more economically, or, can produce more power when you need to.
Here is a link to and the conclusion from a recent Applied Physiology article-
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http://jap.physiology.org/cgi/content/full/86/5/1527"The improved neuromuscular characteristics of the present E athletes were related to both VMART and RE. Improvements in V20 m, 5J, and CTs of the CVLs correlated with the improvement in VMART during the training period. These results support the observation by Nummela et al. (34) that training utilizing various jumping and sprinting exercises with high contraction velocities and reaction forces results in increases in stretch-shortening cycle exercises such as sprint running and also allows improvements in VMART. Moreover, these results are in line with previous observations that VMART is influenced by the interaction of neuromuscular and anaerobic characteristics and that VMART can be used as a measure of muscle power (37, 38).
Another possible mechanism for the improvement in the 5-km running performance seemed to be related to RE. It has been reported (24) that heavy-resistance strength training improved RE of female distance runners. The importance of the neuromuscular characteristics in determining RE and thereby running performance has recently been pointed out also by Dalleau et al. (8). They showed that the energy cost of running is significantly related to the stiffness of the propulsive leg, which is also demonstrated by the present decrease in the CTs of CVLs and increase in V20 m and 5J in the E group. It has been suggested (9) that the 5% decrease in the energy cost of running explains an improvement in the distance running performance time of ~3.8%. This is in line with the results of the present study, in which RE and 5K time of the E group improved by 8.1 and 3.1%, respectively, and no changes in O2 max were observed. Furthermore, the present correlations between the improvements in the neuromuscular characteristics and RE were statistically significant. All these findings, together with the relationship between the improvement in V5K and RE, suggest that explosive-strength training had a positive influence on RE and running performance because of the improved neuromuscular characteristics. However, RE at race pace is different from that at submaximal running velocity. The significant correlation between RE and VMART suggests that muscle power may influence RE both at submaximal velocities and most probably at race pace.
In conclusion, simultaneous explosive-strength training, including sprinting and endurance training, produced a significant improvement in the 5-km running performance by well-trained endurance athletes without changes in O2 max or other aerobic power variables. This improvement is suggested to be due to improved neuromuscular characteristics that were transferred into improved muscle power and RE. "