high

Resting heart rate and heart rate variability: What's optimal?

resting heart rate and heart rate

variability what's optimal

so first we're looking at a plot of the

relative risk uh for all-cause mortality

against the resting heart rate in beats

per minute and what we can see

is that a resting heart rate of about 45

beats per minute is associated with a

maximally reduced

all-cause mortality risk so with that in

mind

what's my data so i've been tracking my

resting heart rate uh with a

fitness tracker for almost two full

years from august 2018

through june of 2020 and what we can see

is that i started uh

so each blue dot corresponds to the

average uh resting heart rate

for that month so we can see that i

started with a resting heart rate

around 52 to 53 and then i came down

went back up and then went back down

again

and then went back up again so uh

there's a noticeable trend here that my

resting heart rate has been lowest in

the winter

and but highest in the summer so what's

going on with that well

in the summertime i suffer from uh hay

fever so allergies

to grass and pollen and that increases

my resting heart rate for

from may until july at least that's what

happened in

2019 in 2020 i was better able to manage

those symptoms and my resting heart rate

went up less so

that's the trend for me but what about

in the published literature

are there seasonal trends so what we're

looking at here is data from 90 to 92

about 92 000 subjects

and resting heart rate for uh women in

the green line and

for men in the blue line and what we can

see is that

the resting heart rate is actually lower

in the summer for this cohort of 90 000

plus subjects

and highest in the winter so this data

is basically opposite

my data and i just included that to

illustrate that epi

data from large epidemiological studies

are important but

what's more important is seeing how your

data

agrees with it or not and if it doesn't

well you've got to figure out you know

why and how then to optimize it

so based on all-cause mortality risk my

resting heart rate

data is close to optimal so you can see

it my 2020 data

my average resting heart rate is around

47.48

but i didn't include how resting heart

rate rhr changes during aging so let's

have a look at that data

so resting heart rate increases then

decreases during aging and i've included

data

for two different studies here with

basically the same trend

um so we're looking at the average

resting heart rate on the y-axis plotted

against

age and what we can see is that

uh resting heart rate peaks at about 50

in both

cohorts and then declines towards the

end of life

so if you remember my data my resting

heart rate was actually i started at a

relatively high level

and then over the past two years i've

reduced it so how do i know that i'm

i didn't peak uh and then i'm on the

slow downward trend for lower resting

heart rate uh towards the end of life

how do i know

so with that we can look at the heart

rate variability for more insight

about my uh cardiovascular health so

first what is heart rate variability

uh so the simple definition is it's the

variation in time

in between successive heartbeats so if

your resting heart rate is 60 beats per

minute

on average your heart beats once every

second but it's not exactly

once every second some beats may be 0.9

seconds

some beats maybe 1.1 seconds and some

beats may be exactly

one second so if you take the average of

those three sure it's 1b

per minute but the time in itself is

is different that so that's the heart

rate variability it's the variability uh

in the time in between those heartbeats

so we can see that illustrated here by

that picture and i won't get into the

math

but um my fitness tracker measures heart

rate variability uh

with the rmssd which stands for the root

mean square

of successive differences between

heartbeats so the rm ssd why is that

important

uh and how does it change with age so it

declines during aging

and first we can see that here in a

study of about 200 or of of 260 subjects

the rmssd which is basically heart rate

variability that's how they assessed it

in this case

it starts off at about 53 in young

subjects 10 to 19 years old

and then you can see it slowly declines

for each age group

until 80 to 99 year olds then have a

heart rate variability of 21 so

significantly decreased

heart rate variability with age so these

data were confirmed in another study

a little bit bigger 344 subjects and uh

so again the young

adults are actually you know kids uh too

uh so 53 um heart rate variability 53

milliseconds that also declined

all the way from until 70 to 79 years

where they had a 19 millisecond rm

ssd but then note that the 80 to 99 year

olds

actually had an increase to 30. so the

authors of this paper

propose the idea that having a higher

heart rate variability

than your age group may be a promoter of

longevity

so these data are in relatively small

studies though 260 and 344 subjects

respectively what about in bigger

studies

so in a study of 8 million subjects we

can see that data here

but first i want to note that these data

are based on fitbit users so

we may have a healthy user bias in that

the data that i just showed you with the

smaller sample

sizes these are people from the general

population um

and you know fitbit users are more

likely to care about their health

because they're buying a fitbit so

they may be starting or have a higher

level of fitness than the general

population so along those lines we can

see that the the heart rate variability

of the

the fitbit users in this study at a

young age 20 to 25 years old had

uh rmssd so heart rate variability

values uh you know

65 into the 70s whereas the other

studies had

you know 53 was the high so there may be

a little bit of a healthy user bias in

this cohort nonetheless

we can see that heart rate variability

uh declines

uh through aging you know so so from

values uh

you know around 70 and youth all the way

to around 40

in in 60 year olds so um

the low heart rate variability the

importance of that is also illustrated

by the findings that it's associated

with an increased risk for sudden

cardiac death

scd and all-cause mortality risk acm

so first uh this is a plot for the

relative risk

for sudden cardiac death in a a

group of 12 and a half thousand people

and what we can see is that

for people that had that had heart rate

variability uh variability uh

scores rms ssds of less than 18

milliseconds

they had an increased risk for sudden

cardiac death relative to people who had

higher than 29 milliseconds so lower

heart rate variability

uh potentially bad for sudden cardiac

death

and then along those lines uh there was

an increased all-cause mortality risk

that had

uh rm ssds of less than eight

milliseconds so long story short

very low heart rate variable variability

uh potentially bad for all-cause

mortality and sudden cardiac death now

these are values

very low values that you'd expect to see

in someone who's very old

if you look at the fitbit data you know

the average value was around 35-40

so but it's also pop possible you know

with an unfit sedentary life

lifestyle to have very low heart rate

variability so uh having higher

values for rmssd as the measure of heart

rate variability may be important for

cardiovascular and and and health in

general

uh so and just to also illustrate so i

noted that

uh resting heart rate declines with

aging and so does heart rate variability

so if you have a low

rhr and a low hrv that's

worse cardiovascular cv fitness

so what's my data how you know we

started on this path to determine if

um you know my resting heart rate maybe

peaked and now is on the

towards the end of life trend and we're

using heart rate

variability to try to elucidate more of

the picture so what's my data

so here's my data for the past 23 months

uh

and my fitness tracker uses uh the rms

as the

uh metric for heart rate variability so

we can see uh you know slowly uh

increase in and with a you know massive

spike in the winter of uh

2019 into 2020 but an increase over time

and

when i look at the average my average

value in 2018 so august through december

my when i started off my heart rate

variability was 47.3

the full year average 365 days for 2019

was higher

56.2 and then for the first six months

of 2020

i've been able to get it even higher at

61. and one way i'm doing that is by

uh you know use better better

integrating rest

not over training uh monitoring the

intensity and duration of my workouts

and all that collectively over the past

few years that i guess i've been doing a

good job based on my heart rate

variability data so just to bring back

the aging data to illustrate um

the importance of my my data and how it

fits into the literature

so i started tracking when i was 45

years old and just based on the fitbit

users in this study

the average heart rate variability the

rmssd was around

38 you know 40 somewhere in that

ballpark so already

even though my training and rest periods

and all that stuff

was uh sub-optimal at the time compared

to where i'm now

i was still a little bit better than the

average fitbit user uh with you know my

values around 47.

now looking at my 2019 data and how it

fits on this curve we can see that

compared to the average fitbit user my

heart rate variability age is

so is equivalent to that of a 30 year

old which is pretty good if you ask me

uh and then but in 2020 i've also

improved so

um you know one can one could argue that

you know relative

to my chronological age i've got the

heart rate variability of someone that's

closer to 26 years old rather than 45

years old and i'd argue that may be one

of the reasons why i have a relatively

young

biological age as indicated by levine's

phenotypic age calculator uh

video i have a video on that if you're

interested just check out my videos

so uh collectively my

eight my reduced heart rate uh resting

heart rate over time

but i have a reduced rhr over time but

an increased heart rate variability

so i'd argue that i'm on the right track

so the idea that

i hit the peak for resting heart rate

and now i'm on the slow age related

decline towards death

based on my heart rate variability data

in combination with the resting heart

rate data

i'd argue that that's not the case so

you can find me lots of places online

if you're interested reach out have a

great day