Change in calories burnt

Former Member
Former Member
Hi there, I am completely new to this thread. I have not swum in years although I swam competitively all the way through university and then basically swam with my kids and grandkids. This year, as part of a whole 'get healthy' lifestyle change I have added swimming back into my exercise routine. But I am confused about something and hopefully there are experts out there who can help me. When I started 4 weeks ago I swam 1010 meters in 30 minutes, with an average 116 strokes per 100m (breaststroke). My calories burnt showed as 412 on my Apple watch. Yesterday I swam 1320 meters in 30 minutes, with an average of 66 strokes per 100m and my calorie count was 285. It has been steadily decreasing even as my speed increased, and my strokes improved. I know I am not going to win any contests, but at the moment I am not worried about that. Just interested why the calorie count decreases although I am a more efficient swimmer. I have lost another 3-5lbs in that time, so that is not my concern, although that may play into it. I have about another 10lbs to reach my final weight loss goal. Any input will be really helpful.
  • Are you swimming in a pool or open water? Those distances seem a bit odd either way, but more in-line with o/w. Are you swimming all freestyle, or incorporating in other strokes too? I also use an Apple Watch when I swim. When I swim freestyle in a pool, I usually burn about 100 calories for every 500 yards. Sure that might vary a bit, mostly when I do other strokes (even a little butterfly increases the calories burned quite a bit). If I do sets of repeats (say 10 x 100 @ 1:30), the calories burned goes up a bit too -v- just casual long sets. When I swim open water the calories burned varies drastically. I usually do mostly free when I'm in o/w (I usually use a buoy and haven't gotten used to backstroke with the buoy). It isn't unusual for me to burn 1500 or even 2000 calories in an open water swim. My watch may say that I've burned tons of calories when I don't think I have (flat water, easy to go faster) and other times not (tons of wind and chop). I more swim o/w for overall time and a lesser degree for distance. All this said, it is good that you are back to swimming. I'd probably focus more on getting yourself in the water for right now, perhaps work on some technique, and not so much on the calories. After you start to settle into a more defined schedule, I don't think you'll see as much of a variance.
  • Do you want to burn a lot of calories swimming? Swim like a first-timer, trying to escape being devoured by a great white shark. :afraid::drowning: In other words, swim as inefficiently as possible, flailing your arms and legs all over the place. The more efficient you swim, the less calories you will burn for the same distance, if every other factor is equal (an apples to apples comparison). So, your calorie count decreased BECAUSE you were swimming more efficiently.
  • Maybe the drop in stroke count and heart rate caused this. Glad you made it back to the water, welcome.
  • The above is true, but there also may be some atrifact as I suspect your watch has stroke count as one of the measures. More efficient will show up as less calories even if you are actually really exerting yourself each stroke.
  • As you get into better muscle shape, you will swim more efficiently and use less motion to go the distance. I M O
  • You have two choices: Simply swim further which wouldn't even take more time as you are swimming further per stroke, or as Elaine mentioned pick up the tempo but for that long of a swim you can't go anerobic till the last few meters or so. I also wonder do Apple watches that measure calorie consumption work in a sport like swimming which uses both arms and legs simultaneously?
  • I also wonder do Apple watches that measure calorie consumption work in a sport like swimming which uses both arms and legs simultaneously? This article is a bit dated, but it gives a snapshot of some of the tests Apple uses for the fitness portion of the Apple Watch: www.iphoneincanada.ca/.../ 9to5mac.com/.../ Along with that, I've heard they use some potential Olympians for testing swimming in different length pools (25 yard, 25m, 50m), and open water.
  • Nice story Aztimm especially the first one. The one remaining variable might be the pool temp. We have two pools here in Eden Prairie one is considerably warmer. When I get out of the cooler lap pool I'm much hungrier than a workout in the warmer pool. Any thoughts?