I came across the Rockport Fitness Walking Test, which is used to guesstimate VO2 for middle-aged and older people. I’m doing good on the treadmill at the gym, and I’ve been writing my numbers down in my little logbook. So, plugging the numbers in - Age: 65. Weight: 235. Distance: 1 mile. Time: 24 minutes. Pulse: 122. Speed: 2.5mph.
Various online calculators (the formula is a morass of constants and fudge factors) return results around -1.2.
The acceptable range for ages 60+ starts at 20.5 for "very poor", to 34.5 for "good".
WTF?
Okay, lets play with the calculator. The weighting for speed is very strong. To get to "poor" I would have to trot along at 5mph.
Whaaaat?
The Rockport protocol insists on "walk" and prohibits "run." So, how fast is "walk", anyway?
At 2mph I zoom around people at the grocery store like a pachinko ball. I can guess speed pretty good for that, since I do most grocery shopping on the way home from the gym. At 2.5mph I’m lapping most of the people on the gym’s indoor track. I can do about half a mile at 3mph, but that’s up on my toes and not really a "walk" any more. I haven’t seen anyone around my age on the treadmill, but I’ve blown past them on the track as they shuffle along, probably less than 1mph.
There are some charts for "average walking speed by age" online. Whoever came up with the original charts was smoking crack. An example:
age 60 to 69: 2.77 to 3.0 mph
age 70 to 79: 2.53 to 2.82 mph
age 80 to 89: 2.10 to 2.17 mph
Riiiiight. I doubt many 69-year-olds could manage 2.77mph if they were being chased by wolves, much less for an "average walk." And certainly not for the full mile the test requires.
The Rockport number is theoretically used as a guide to general and respiratory fitness. Though I find its expectations for speed to be completely unrealistic, I routinely collect all the information its formula requires, so I’ll do a calc and enter it on my spreadsheet every month or so.
Bonus factoid: what’s the difference between "walk" and "run"? That turned out to be surprisingly hard to tickle out of search results; apparently it’s so obvious it’s seldom a question. The most likely definition seems to be that walking always has at least one foot on the ground at all times, while running means both feet are off the ground sometimes.