Say a 6-ft tall person runs 5K in 30 minutes. How much longer would it take a comparably fit 5-ft tall person to run the same 5K?
Smart ass answer deleted.
Having the same VO2 Max means little. One runner may have better efficiency or better leg speed.
It depends.
The key to speed is turnover, the more paces per unit time, the faster the pace. Then consider stride length. Given the same turnover pace, longer strides yield faster course times. Then factor in leg length - longer legs yield longer strides.
I’m assuming comparable fitness, efficiency, similar relative leg speed.
Are you asking how long a stride they would have, and then assuming they take the same number of strides per minute?
You can’t just say well the 5 ft person is 5/6th the height of the taller person and therefore runs 5/6th the distance in the same amount of time. You have to consider a lot more than just stride length. Larger people have more mass to move around, and muscle strength doesn’t scale up with mass (which is one of the reasons we don’t have six foot tall insects). If larger (longer stride length) was always better, your best long distance runners would be really really tall, and they aren’t. Experience has shown that the best long distance runners are of average height, and have a thin build.
Since you have one person on the tall side of average and one person on the short side of average there’s a good chance that they’ll finish about the same.
Other factors like limb length vs. mass, lung capacity, and muscle composition and structure are going to be more significant than their height.
Shorter, more muscular people do better at sprinting, by the way. The ideal body type for a sprinter and an endurance runner are not the same.
During the recent Olympics I seem to recall the commentators making a point of this, that turnover speed was generally more important than sheer height - Usain Bolt at 6’ 5" is markedly taller than a lot of the other sprinters. One of the top Americans was about 5’ 7", most of them looked to be medium height (around 5’ 10" or so).
Also, stride length is not a direct function of height. I am a little over 6 feet tall (183.5 cm) but have a long body and short inseam (I wear 32" inseam pants).
I was going to mention this - my hubby is 6’2", but has a 30 inch inseam (stubby legs).
I have a longer inseam at 31 ish and I am 5’9"
My reason for this question is I’m considering talking to my teen’s Health teacher. She is having them run a distance of 2.8 miles, and grading based on their times - 25 minutes equals an “A”, 30 minutes equals a “B”, etc. They have two practices a week. I see so much wrong with this system of grading: some kids are quite overweight and will probably not be able to achieve an “A” within one semester, some kids like my daughter are under 5-ft tall and seem to be at a disadvantage compared to the taller kids, there’s plenty of undiagnosed exercise-induced asthma out there, it doesn’t account for any individual variations, boys vs girls, etc. I believe grading should be based on effort and perhaps improvement, not a specific time per se. My kid may be able to reach this goal, but she’s totally stressed out about it as she’s an excellent athlete but has never had good long-distance endurance. The weather here is too miserable to put in much practice. I don’t want to butt in with the teacher if I’m way off-base. I realize that taller inseams means longer stride but also longer time (turnover?) per pace, but I don’t know how this translates to real world other than my own observations. My husband is a foot taller than me and within seconds has me outpaced, but I’m a terrible runner and he runs like a gazelle. I see no reason to penalize kids for things they have little control over irrespective of effort expended.
While you probably do have a point about the grading not being fair, your daughter’s height isn’t what is putting her at a disadvantage compared to the others. Her leg length relative to her height compared to the other kid’s leg lengths relative to their heights (which none of the kids have control over) is much more of a determining factor.
I also take it from your description that she is “an excellent athlete but has never had good long-distance endurance” that she probably has a body type and muscle structure more suited to sprinting than endurance. Sprinters, even really good ones, tend to suck at long distances.
Yun Bok Soh of South Korea won the Boston marathon in 1947. He was only 5’1 (he’s the shortest winner on record). The tallest person to ever win the Boston Marathon was only 6’2. Being tall isn’t an advantage for distance running.
2.8 miles in 25 mins = 6.72 miles/hr = 8.93 mins/mi
2.8 miles in 30 mins = 5.60 miles/hr = 10.71 mins/mi
2.8 miles in 35 mins = 4.8 miles/hr = 12.8 mins/mi
I’d be failing for not running 2.8 miles, but if I did get the miles in (walking counts), I’d be failing for not having the time. My best was about a 12 min mile and only running 1 mile. 
Seems to me, if this is a Health class (rather than a running class), what is far more important than any particular speed is to establish a consistent practice and do it regularly. Maybe showing improvement from beginning of class to end of class. Goals individually determined. The idea is to make kids healthy, right? Not just punish the slow ones?
- One of the slow ones.
Thanks. That’s very informative and helpful. My daughter does have a very compact, muscular frame. It won’t be the end of the world if she only gets a “B”. I do have overall problems with the whole idea of grading this feat as far as all the students go, not just her. I’m glad to have accurate information instead of my WAGs.