“How do you run quickly when you’re such a short arse?”
My reaction to this was twofold, one part of my brain started to analyse stride rate, stride length and how they combine to influence run performance. The other part of my brain was hung up on the fact that ‘short arse’ was indeed a little harsh considering I’m 5’9 on a good day, 6′ in my HOKA’s.
It is a question that I’ve been asked many times, surely if you are short with proportionally little legs, you have to take far more strides than a taller runner with his irritating, lanky, ‘look at me I’m over 6′ tall’ frame. The answer is dictated by your definition of key terms, let’s explain further!
Stride Length V Stride Rate
Stride length is simply how far you stride. My old running coach used to tell me to stride out and reach a little further. If I could increase my stride length by an inch each time, those inches would add up to a mile by the end of a marathon! The problem with ‘increasing your stride length’ as we have discussed many times is that it tends to lead to heel striking, whereas taking shorter strides promotes the preferred mid/forefoot landing. I’m not going to discuss the benefits of shorter strides and forefoot striking as we’ve done that lots of times already on this blog, check older posts if your interested.
Stride rate is how quickly you stride, generally measured as strides per minute. An average runner may take 170 strides each minute (most people only count on one leg, e.g. 85 right foot strikes per minute). If a runner completes a training run, with a stride length of 1.5m and a stride rate of 170, then in one minute they would travel 255m (1.5m per stride x 170 strides). This equates to 6 mins 18 secs per mile and if they want to go faster this can be achieved by increasing stride rate, stride length or both simultaneously. This sounds simple right? We haven’t even got started yet and this is where it gets good..
In your head, how would you describe stride rate?
In my head, I would describe it as the furthest distance between my right and left foot when I am in mid flight, in simple terms, how far apart do my feet separate. If you are a short runner with little legs, it’s likely that your feet will not separate as much as those taller runners with their longer legs. It won’t be the case all of the time, but as an average, it’s fair to presume that longer legs will naturally result in a longer stride length.
Look at the picture below, if you could take a tape measure and measure the distance between their right and left feet when they are at maximum distance apart, that would give you stride length. If all of the runners below were using the same stride rate (180 strides per minute) then the runner with the longest stride would win.. right? In fact this isn’t the case at all, stride length isn’t actually that critical, it’s flight distance and flight time which really decide who wins.
This simply refers to the distance you cover between your left foot leaving the ground and your right foot hitting the ground (or vice versa). When running quickly, after your left foot leaves the ground, you then fly through the air (not being in contact with the floor) until your right foot hits the ground. The further you fly through the air and the greater the distance you cover before landing again, the greater your flight distance.
What’s the difference between stride length and flight distance?
Stand with your feet together and jump as far as you can, landing with your feet together (commonly called a standing long jump). measure how far you traveled from take off to landing, that’s your flight distance. I already know your stride length, it’s zero, your feet didn’t separate, they stayed together at all times during take off, flight and landing. I told you this was going to get good..
Imagine you’ve got little legs and your stride length isn’t very big (your feet don’t get that far apart). Now imagine your little legs are so powerful that when you take off, you fly 2.5 metres before you land on the other foot. By contrast, imagine a tall runner with long legs and a big ‘stride rate’. Unfortunately this tall runner isn’t powerful at push off and almost as soon as he’s got airborne, he’s landing again on the other foot, with a total flight distance of 2 metres.
What’s the relationship between stride length and flight distance?
Something worth considering is that forefoot landing (easier when running with shorter strides) allows runners to generate more ‘plyometric’ energy return, using natural bounce in the foot and knee. This greater plyometric return / bounce will lead to greater flight distance. By contrast, heel striking reduces plyometric return, thereby potentially reducing flight distance. In simple terms, trying to increase your stride length, may well decrease your flight distance. I’d bet that most people trying to increase stride length, do so because they are in fact trying to increase flight distance.
Can you handle one more thing? OK.. let’s quickly mention flight time
Without making this whole article too confusing we do have to mention flight time, the easiest way is to give another running example. If a runner has a stride rate of 180 strides per minute and a flight distance of 2 metres per stride, he’d travel 360m per minute (2m X 180), this is slight quicker that 4 minutes, 30 seconds per mile (dream on..). One of the key problems which may prevent people achieving this is how long they spend in the air, now bear with me on this part. If our super fast runner completes 180 strides per minute, that equates to 3 strides per second and each of those strides covers a 2m flight distance!! Do the maths, as the foot takes off, the runner flies 2m through the air and has to touch down in less that 0.3 of a second. If he doesn’t fly quickly enough, he’d never manage to complete 3 strides per second!!
Try this.. bound from one foot to the other and try to travel as far as you can each stride, maximise your flight distance. I’ll bet that some of you can easily bound 2 metres per stride but you’ll hang in the air with a ‘pause’ in your running style, land, bound, hang and pause, land, bound, hang and pause. So, you’ve managed to travel 2 metres, but your stride rate (strides per minute) is now incredibly slow. You need to travel 2 metres, but couple it with a 180 strides per minute stride rate.. sorry to bring you that news.
What’s the conclusion to this article?
The main driver behind this article was my dislike at being called a short arse, but it has now ‘grown legs’ (like what I did there) and developed into a more structured discussion. The main points I would take from this are:
1. Do not to confuse stride length with flight distance, they are different things (in my head at least)
2. Be aware that by trying to increase stride length, the subsequent changes in technique (heel striking) may reduce flight distance
3. Flight distance and flight time are generally governed by force production, largely plyometric energy return
4. Never pick on little people.. we will crush you.
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