I Have used all four versions of the watch and have great familiarity with the exercise features. During the past 8 months I have used the exercise rings daily for an identical walk with my dog. The 8 month daily walks have produced remarkably consistent data. The walk is slightly under 3 miles (+/- 0.1 mi), consumes approximately 300 calories at my size (+/- 8 calories), and rates as 37+/- 2 exercise minutes. This is important because I installed Watch OS 6 and IOS 13 yesterday. I checked everything after the install and made certain my settings were unchanged. Today, I took the same walk. Distance 2.95 miles, Calories 303, Exercise time - 26 minutes. Thus my query. What has changed in the exercise time calculation that results in a 33% reduction in a time consistently recorded for 8 solid months? Anyone else notice this anomaly?
Change in exercise algorithm?
Mrfearless, I noticed this behavior recently in Watch OS 5.3 ß — I do the identical walk with someone lighter and their exercise minutes are about 30% higher. Identical pace, stride, arm swing, etc. I burn more calories, their watch displays more exercise minutes. If I engage an "Other" workout activity, the results then become similar (30% more exercise minutes).
I have noticed the same issue when I go on the treadmill. As watchOS 6 my workouts are consistantly 0.10 - 0.15 mile lower than what my treadmill records. Back on watchOS 5, my watch and treadmill were usually within 0.05 of a mile. Not sure why it is doing this and my calories burned have usually been within 10 kcal of each other (watch and the treadmill) sometimes up to 30 kcal. I have also noticed that I have missing heart rate data when I look in Health (not always, but sometimes).