In With the Coming of the Apple Watch, Digital Monitoring is the Next Big Thing, I suggested that Apple Watch would be a Really Big Deal. After watching :; the Apple videos, it seems that the fitness aspect alone could do millions a world of good. At least the slick presentation makes it appear that Apple has hit the nail on the head in making a fitness device that is light years ahead of previous efforts. It looks exceptionally well done in its mass market get-off-the-couch motivational potential (at least for a few weeks of use!).
And yet I was deeply disappointed in what was shown, or at least what was not mentioned, because Apple Watch appears to lack a critical thing: ANT support. As a cyclist with measured exertion of 7000 to 10,000 kilojoules per week (multiply by 0.956 for kilocalories* aka “calories”), I care about what it can do for me on my bike. Moreover, you must carry the iPhone (for its GPS) if you want things like speed and distance (but GPS performs poorly under trees and on twists and turns and switchbacks and many other places). AFAIK, the iPhone does not support ANT either and never has.
* The 0.956 conversion factor relates kilojoules (watts of power) as measured on the bike to 1% accuracy to an efficiency factor for the human body in converting chemical energy to work (muscles) for a highly trained athlete.
Thus if 1000 kilojoules of work are produced on the bike, 956 kilocalories of food must be eaten to produce that resulting mechanical work (most of the energy is wasted as heat, which is why exercise makes us hot). Hence the conversion factor between kilojoules/kilocalories is not 0.239 <=> 4.187 when calculating caloric intake vs measured work (exercise).
The generally accepted range of human body efficiency in converting chemical energy (glucose, fat, protein) to work (physical movement) ranges from 18% for an untrained non-athlete to 24% for a highly trained athlete. So one kilojoule on the bike (as measured) is roughly one kilocalorie of food for a highly trained athlete at steady effort, e.g., 0.2390 X (1/.240) = 0.995.
Having tracked caloric intake to the gram for years as part of training, I should probably raise my efficiency factor to 0.24; food and training logs suggest that my 0.956 figure is too low (e.g. I have high efficiency). But post-workout there are caloric needs for recovery and repair and growth, thermic losses during digestion (TEF), and also exercise intensity varies the metabolic efficiency (type of energy source), so I deem it more useful to stick with 0.956. Simply digesting and converting food to usable energy takes from 5% (fat, certain types of carbohydrates) to 30% (protein) of the calories consumed (thermic losses aka specific dynamic action (SDA)). So five years of weight/calorie/excercise data tells me that 0.956 is a highly accurate number for my own food and exercise habits.
ANT wireless data transmission
ANT is the wireless standard for sending/receiving instrument data to a “head unit” like an SRM PC7 or Garmin Edge or dozens of others (and, one would have hoped, Apple Watch Sport).
When I cycle there are seven (7) data streams to be recorded: heart rate from a band I wear around my chest, power and cadence from the SRM DA9000 power meter, speed and distance accurate to 0.1% from a carefully calibrated per-revolution wheel sensor. And elevation and temperature. All of which are transmitted via ANT. [Long and varied experience over years also proved to me that GPS is far too often way off for elevation and ascent, so it that too is garbage from my training perspective].
So unless the Apple Watch can record these data streams, it’s useless for my cycling purposes. It’s all good that millions of fair weather cyclists and runners and etc are to be served, but I sure hope that my disappointment is only due to an omission by Apple of stating ANT support.
That Apple has any intention of supporting this kind of data collection seems like a crackpot idea given the way Apple thinks—and yet millions of serious athletes would surely like to be able to use an Apple Watch Sport to make it happen.
3248 kilojoule extensive endurance cycling workout
64 miles + 6538 ft elevation gain @ 217 watts, 133 bpm, 4+ hours