This is another post on information gathered at the USATF Podium Education Project in Las Vegas. Like last year, this was a conference with coaches and scientists/researchers of the best of the best – Olympic level athletes. My goal is to share some data and information as well as share some practical considerations for age group, youth and masters athletes.
There were several presentations on gait analysis. We all know that basically longer strides or faster leg turnover are about the only ways we get faster. Two related variables are ground contact time (GCT) or, the amount of time your foot actually remains on the ground; and air time – the time you are not in contact with the ground, in mid stride. Over the years I have read or heard it’s important to decrease GCT (get up on your toes) and to reduce air time.
Dr. Robert Chapman is at the forefront of gait analysis. Here are some of his findings.
Note: Running economy is the oxygen cost at a given pace.
Dr. Chapman has found that when stride frequency increases with decreased contact time it simultaneously increases oxygen consumption. To understand this; in order to spend less time on the ground it requires greater force applied to the ground which yields increased oxygen consumption. Therefore it may not be better for distance runners to decrease their GCT at least in the bulk of the race. It would adversely affect running economy. It is better to save that reduced GCT effort for the last stages of the race. (By the way, they use really cool 600 frame per second high-speed cameras to retrieve all their data. Sorry, you can’t do this with TV recordings.)
He also found that there was a tendency for taller runners (males especially) to have increased GCT while shorter runners had decreased GCT. Though there were trends found in specific event specialties (longer versus shorter race specialists) there was just as much variability within individuals. So, for instance 1500 specialists reduced time in air to get faster But, 5k and 10k tended to reduce contact time to get faster. Yet, there was a lot of individual variability within 1500 specialists as well as within 5k specialists.
For sprinters reducing GCT is a very desirable thing. Sprints are pure power and the aerobic aspects of racing are minimal in short races. Therefore this is a key variable in getting to be a faster sprinter. This lesson is not lost on distance runners however! If you want a more powerful kick at the end of races, training for power and speed will augment your ability to do so by decreasing that GCT. And at that late point of a race sitting back in hopes of conserving oxygen consumption is a moot point. Get to the finish line!
As a practical observation it means that performance itself (times) may be more dependent on the ability to decrease GCT during kick vs. having a short GCT in bulk of race.
So, shorter GCT is something distance runners can benefit from late in the race. This means distance runners must do speed work. It will mean the difference in faster times and faster finishes. However, to strive to reduce your GCT throughout the race is more than likely counterproductive. It should be addressed “organically” – as part of training. This means that it should not be addressed by arbitrarily trying to “get off the ground” or “run on your toes/forefoot.” This is arbitrary, counterproductive and may in fact greatly increase likelihood of injuries.
The message is clear – if you want to breakthrough to another level of racing, quality workouts are how you attack it.