Forerunner 965 Active Calories Burned Too High

  • I am new to the Garmin ecosystem and have just bought a forerunner 965. The watch is great however I have noticed that my active calories are way too high. 
  • I setup my account the other day and all stats are correct. However today on a 8.5 mile bike over 1 hour 5 mins the watch is saying i burned 1064 calories (959 active calories)
  • All other stats are realistic and as expected. Heart rate appears to be as expected.
  • Can anyone offer any insight into why this could be happening?