A fitter heart is a more efficient heart, able to do the work of circulating the blood in less beats. Most types of exercise \u2013 including yoga \u2013 have been shown to push down resting heart rate by about five beats per minute<\/a>.<\/p>\n But there\u2019s a lot of individual variation within the \u201caverage\u201d resting heart rate. Younger, female hearts beat a little slower than older, male hearts, for example.<\/p>\n And don\u2019t try to compare your resting heart rate with your friends, Scott says. \u201cWe\u2019re all getting older. Maintaining the same resting HR, rather than improving it, is still an improvement.\u201d<\/p>\n If you put your finger to your pulse, it feels steady and rhythmic. But under close examination, the rhythm reveals minute variation \u2013 literally between every heartbeat.<\/p>\n The Apple Watch emits a green light when measuring the wearer’s heart rate.Credit: SMH \/ Supplied<\/p>\n Why? Because of the way the heart is wired up. The heart beats in response to electrical signals from the nervous system. The two halves of our nervous system \u2013 the sympathetic and parasympathetic \u2013 are designed to be in constant tension with each other.<\/p>\n The parasympathetic nervous system is our brake, always pulling us towards calmness and tugging our heart rate down (when the parasympathetic nerve is cut during a heart transplant, heart rhythm rapidly accelerates). The sympathetic nervous system is our accelerator, looking for stress, primed to trigger our fight or flight response.<\/p>\n Loading<\/p>\n \u201cThere\u2019s always a tension between the two. If heart rate variability is high, that\u2019s a really robust nervous system,\u201d says Dr Kegan Moneghetti, head of cardiovascular clinical services at the Baker Heart and Diabetes Institute. \u201cHaving a higher heart rate variability is good for the heart, and good for the body.\u201d<\/p>\n Higher heart rate variability is a sign both sides of the nervous system are in robust health. As we become more stressed, our sympathetic nervous system grows more active, and our heart rate variability falls: researchers consistently see lower HRV in people who are sick<\/a>. It\u2019s a sensitive metric, pushed up by exercise and down by alcohol, weight gain, or job stress<\/a>.<\/p>\n And it is an excellent measure of how well your body is adapting to training, says Professor Andrew McKune, senior adviser on recovery to the Australian Institute of Sport. Generally, the average weekend athlete will see their HRV increase after training<\/a>, as their bodies adapt to stress. But if they approach exhaustion-levels of exercise, their HRV will fall, only rebounding after a big rest-break.<\/p>\n \u201cFor myself \u2013 as much as I can be a bit of a sceptic for these \u2013 it does seem to be a pretty good indicator of when I\u2019m going to get sick. I can see it trending down for three or four days, and I\u2019ll say \u2018uh oh\u2019 to my wife,\u201d says David Scott.<\/p>\n But he and other experts caution against reading too much into the exact HRV your smartwatch spits out. McKune typically spends a month monitoring an athlete\u2019s HRV to work out the baseline. Your individual trend \u2013 up or down \u2013 is what matters.<\/p>\n \u201cIt\u2019s one component you might look at with interest. But we don\u2019t say your HRV is 20, you need to do this and this,\u201d says Moneghetti.<\/p>\n Sekulovski in a hyperbaric oxygen chamber at P3 Recovery.Credit: Justin McManus<\/p>\n Sleep, recovery, and readiness scores<\/b><\/p>\n First-generation smartwatches merely tracked our health metrics. The modern versions try to turn these data points into scores: sleep scores, recovery scores, even readiness scores.<\/p>\n Loading<\/p>\n Let\u2019s start with sleep. Scientists use brain electrical activity to monitor our sleep and break it up into phases: light, deep, and rapid-eye-movement (REM) sleep. Smartwatches don\u2019t yet have the ability to eavesdrop on our brains, so they try to replicate that data by measuring how much our bodies move as we sleep, combined with heart rate and heart rate variability data.<\/p>\n \u201cIt\u2019s all algorithm based,\u201d says Dr Donald Lee, a sleep physician at the Woolcock Institute of Medical Research. \u201cIt\u2019s indicative and not authoritative \u2013 take it that way.\u201d<\/p>\n Not getting enough sleep long-term increases all-cause mortality and the risk of several chronic diseases<\/a>. There\u2019s a lot of individual variation in how much sleep is enough, but consensus medical guidelines encourage you to aim for seven to nine hours a night<\/a>.<\/p>\n What about sleep quality? That also matters: guidelines <\/a>suggest the best sleep involves falling asleep 15 minutes after your head hits the pillow, waking one or less times a night, and not having extremely high levels of REM or extremely low levels of deep sleep.<\/p>\n Beyond that, is there an optimal amount of REM or deep sleep we should target? \u201cI hear it all the time: I\u2019m not getting enough REM, or enough slow-wave,\u201d says Lee. \u201cThere is no great robust evidence that says increasing or decreasing certain stages is beneficial.\u201d<\/p>\n Loading<\/p>\n Even with those limitations in mind, Lee sees a role for smartwatch sleep scores, but suggests you focus on the trend, not on how you did in any individual night. \u201cBe fascinated by the data that comes back from the devices,\u201d he says. If there are problems, talk to a sleep doctor.<\/p>\n That\u2019s sleep. What about recovery?<\/p>\n A small meta-analysis of seven studies on HRV<\/a>, published in October, concluded heart rate variability did change meaningfully as people went through periods of stress and recovery. A 2023 meta-analysis of 17 studies found various recovery techniques \u2013 including massage, cold water immersion, stretching and massage \u2013 meaningfully increased HRV<\/a>.<\/p>\n But just because HRV is a useful metric, it does not mean \u201crecovery\u201d or \u201creadiness\u201d scores are. HRV is a component of these scores, but they are generally proprietary, and the companies do not share how they are calculated. \u201cWe can\u2019t get into them to understand how they are developed,\u201d says David Scott. \u201cThe reality is, there\u2019s not a lot of evidence behind them as to do they really predict if we\u2019re prepared for peak performance.\u201d<\/p>\n![\"The](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/12\/604ce3a614f2af9f5546f79c50a425bea569b90c.jpeg\")
<\/p>\n![\"Sekulovski](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/12\/1f4c687463329b16163e24a607c953f914dc3b74.jpeg\")
<\/p>\n
![\"Sekulovski](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/12\/26c75c559ae7d0bfec3ca7127842214d1f8efe8a.jpeg\")
<\/p>\n