Body Battery

Former Member
Former Member

I can't understand how body battery works.  It is as if that part of the app doesn't communicate with the rest of the app features.  This morning I swam 2.25 miles over the course of about 1.5 hours and my body battery went up 12 points!!  During this time the data show I had burned 720 active calories.  How can I burn that many calories and have the body battery show an increase??  Two nights ago I slept for 6 hours and 5 minutes and my body battery went from 39 to 50.  (I usually see a much more substantial gain in body battery with that much sleep.)  That day (yesterday) I swam 1.7 miles and my body battery went down 12  points.  Ten days ago body battery went from 9 to 52 with 8 hours hours of sleep but with 18,000+ steps the next day it only dropped 12 points all day long.  All of this doesn't make much sense to me.  Is my app and/or Instinct functioning normally?  I am up-to-date on updates as far as I know.

  • According to reports, alcohol consumption significantly reduces body battery.. Anyway it's just an algorithm made by firstbeat. It combines the heart rate, movement, etc to guess your available energy. Just like the vo2max in other watches it's just an estimate. Sometimes it's accurate sometimes it isn't.

  • my body battery went up 12 points!!

    I havent observed anything like that before

    Two nights ago I slept for 6 hours and 5 minutes and my body battery went from 39 to 50.

    how many hours you sleep is not much more important for the measurement  but how well you sleep. I mean it's just related with the stress level. if your stress level is up during sleep, the body battery recharging rate will be slow. fitness level is very important for the algoryhtm to calculate recharging and decharging rate.

  • The instinct can't properly record your heart beat while swimming, I suspect that this is the reason behind the wrong calculation. I also agree that alcohol consumption will not let you get a proper rest during your sleep. 

  • Hi,

    Body battery is based on HRV (heart rate variability). HRV can only tell you if your parasymphatetcic nervous system is more active (rest, irregular heart rate) or symphatetic nervous system is more active (cortisol spike, immune response cause heart to beat in more regular rythm). Yes, 'more active' - they are both active all time, just one dominates.

    Body battery is primarily based on HRV (stress data in garmin) and it needs some time to adjust to your body reactions. If you drink some alcohol you don't rest normally (welp, your body is poisoned to some degree, no surprise). For me body battery is quite effective indicator of immune response, in some cases overtraining (if I'm feeling good but my body battery is dropping fast I dial down my workouts a bit, since it usually means I'll get sick or I overdid last week or two). Paradoxically when you have a very strenous training, especially in the evening (like 3-4 hours of run, or super fast 10k run etc) your symphatetic nervous system might be triggered and cause poor sleep (not sure exactly but it might be related to cortisol and supressing melatonine). Body battery takes some extra data into account to give you a simple indicator how are you doing energy-wise. I think it's ok if your mood does not reflect body battery energy level - when I finish 25km run I'm super energized, due to cortisol spike and I feel like I could go for another run - for hour or two, then I get tired as my stress goes down a bit. If you google 'HRV and illness' or 'HRV and overtraiing' you will find that the best way to use this data is to use stress (HRV) combined with resting HR to predict those things. Generally if for last day or two you resting HR is higher and your body battery is dropping it's a fair indicator that something is wrong :)

  • Also one interesting observation regarding stress and body battery - when I'm dehydrated my stress levels rise. I coupled this with drinking test (hehe, not alcohol drinking - you weigh yourself before run/bike/etc and after and based on the difference you can tell how much underhydrated you were during activity) - especially during long activities (>2h) dehydration can significantly impact stress levels for several hours after finishing activity. Also - even if I drink a lot after the activity I can't compensate for lost water and electrolytes - being hydrated throughout activity has much better results. But theese are just mine observations, no hard data Slight smile

  • The body battery on my Instinct has also been wonky lately.  It usually goes up to around 80-100 when I sleep.  Then it goes down to around 30 during the day (I'm pretty active and exercise quite a bit). Most of the time it seems relatively close.

    For the past three days, however, when I sleep an average night it only goes up 10 points.  So I woke up this AM after a decent night's sleep and my battery went up from 6 to 18. It's done that the last few days.  I feel perfectly fine, I'm not sick, not drinking alcohol, staying hydrated, etc. 

    I'm not losing sleep over it - I know the body battery isn't an exact science. But it is annoying to see my body battery down there at 18 after a good night's sleep! 

  • Good day. I own a 945 forerunner and Instinct. I don't understand why Instinct in Garmin Connect doesn't show the white battery line as the Forerunner 945 does? And why is there a lack of the ability to add a screenshot to the forum?

  • And why is there a lack of the ability to add a screenshot to the forum?

    Because you don't know how?

    HTH

  •  Sorry. I didn't see the picture icon. back to the body battery problem. on the left shows a white line forerunner 945 and on the right instinct no

  • Do you have your Instinct set as your Preferred Activity Tracker in Garmin Connect?