What does the data tell us, and what’s actually useful?
Stefanos Sifandos has access to almost every rescue toy.
But before the chief medical officer at P3 Recovery puts on those self-inflating compression pants or steps into the hyperbaric oxygen chamber, he needs to answer a basic question: how is the recovery process going?
Exercise is the intentional straining of our bodies to the point of minor damage. Micro tears open in our muscles. Inflammatory cascades begin. If done right, we wake up sore the next day as our bodies begin to adapt and get stronger.
So how do we know when adaptation has occurred and when we are ready to get back on track? Sifandos turns to the measurements tracked by his smartwatch on his wrist. “They are great at showing trends like sleep duration, heart rate variability, resting heart rate,” he says. Along with these three measures, sleep quality “tends to be the most helpful,” he says.
Most modern smartwatches give you this data; some now combine various data points with sleep, recovery (Whoop), or readiness (Fitbit and Pixel) scores.
So what does this data really tell us about our health? So how can we make the most of this?
Heart rate, resting heart rate, and heart rate variability
Our hearts are located roughly in the middle of our chest and beat approximately 100,000 times a day. Every hit pushes approximately 70 milliliters of bloodabout a quarter of a baking dish. The average human heart rate has around 70’s.
David Scott, an associate professor at the Institute of Physical Activity and Nutrition, pays close attention to heart rate, both during training and at rest (his Garmin smartwatch tracks it between 45 and 50).
A. Meta-review of 87 studies on resting heart rateResearch published in 2017 found that a 10-beat-per-minute increase in resting heart rate increased the risk of heart disease, stroke, heart failure and cancer by about 10 percent and increased the risk of all-cause death by 17 percent.
A fitter heart is a more efficient heart that can circulate blood with fewer beats. Most types of exercise, including yoga has been shown to reduce resting heart rate by about five beats per minute.
But there is a lot of individual variation in “average” resting heart rate. For example, young women’s hearts beat slightly slower than older men’s hearts.
Don’t try to compare your resting heart rate to your friends, says Scott. “We’re all getting older. Maintaining the same resting heart rate rather than improving it is still an improvement.”
If you put your finger on your pulse, it will feel steady and rhythmic. But close examination reveals tiny differences in rhythm, literally between each heartbeat.
From where? Because of the way the heart is connected. The heart beats in response to electrical signals from the nervous system. The two halves of our nervous system (sympathetic and parasympathetic) are designed to be in constant tension with each other.
The parasympathetic nervous system is our brake, always pulling us towards calmness and pulling our heart rate down (when the parasympathetic nerve is cut during a heart transplant, the heart rhythm accelerates rapidly). The sympathetic nervous system is our accelerator, seeking out stress and preparing to trigger our fight-or-flight response.
D., director of cardiovascular clinical services at the Baker Heart and Diabetes Institute. “There’s always a tension between the two. If heart rate variability is high, that’s a really strong nervous system,” says Kegan Moneghetti. “Having higher heart rate variability is good for both the heart and the body.”
Higher heart rate variability is a sign that both sides of the nervous system are healthy. As our stress increases, our sympathetic nervous system becomes more active and our heart rate variability decreases: researchers We consistently see lower HRV in sick people. increased by exercise, alcohol, weight gain, or work stress.
Professor Andrew McKune, senior advisor on recovery at the Australian Institute of Sport, says it’s an excellent measure of how well your body is adapting to training. Generally average weekend athlete see their HRV increase after workoutas their bodies adapt to the stress. However, if they approach fatigue level during exercise, their HRV will drop and will only recover after a long rest break.
“For me, it seems to be a pretty good indicator of when I’m going to get sick – although I’m a bit skeptical about these things. I can see it trending downward for three or four days and I’ll go ‘uh, uh’ to my wife,” says David Scott.
But he and other experts caution against reading too much into exactly what HRV your smartwatch delivers. McKune typically spends a month monitoring an athlete’s HRV to establish a baseline. What matters is your individual trend (up or down).
“It’s a component you can look at with interest. But we’re not saying your HRV is 20, you need to do this and that,” says Moneghetti.
Sleep, rest and readiness scores
First generation smartwatches only tracked our health metrics. Modern versions try to turn these data points into scores: sleep scores, recovery scores, even readiness scores.
Let’s start with sleep. Scientists use brain electrical activity to track our sleep and divide it into stages: light, deep, and rapid eye movement (REM) sleep. Smartwatches don’t yet have the ability to eavesdrop on our brains, so they’re trying to replicate that data by measuring how much our bodies move while we sleep, along with heart rate and heart rate variability data.
Dr., a sleep physician at the Woolcock Institute for Medical Research. “Everything is algorithmic,” says Donald Lee. “This is indicative and not authoritarian; take it as such.”
Not getting enough sleep in the long term increases all-cause mortality and the risk of various chronic diseases. There is a lot of individual variation in how much sleep is enough, but consensus medical guidelines encourage you to do so. aim for seven to nine hours a night.
What about sleep quality? This is also important: instructions We suggest that best sleep involves falling asleep within 15 minutes of your head hitting the pillow, waking up one or fewer times per night, and not experiencing extremely high levels of REM or extremely low levels of deep sleep.
Beyond that, is there an ideal amount of REM or deep sleep we should aim for? “I hear this all the time: I’m not getting enough REM or enough slow waves,” Lee says. “There’s no very solid evidence to say that increasing or decreasing certain phases is beneficial.”
Even considering those limitations, Lee thinks smartwatches’ sleep scores play a role, but he recommends focusing on the trend, not how you’re doing on any given night. “Awe with the data coming from the devices,” he says. If there is a problem, consult a sleep doctor.
This is sleep. What about recovery?
Small Meta-analysis of seven studies on HRVThe study, published in October, concluded that heart rate variability changes significantly as people go through periods of stress and recovery. A 2023 meta-analysis of 17 studies found a variety of recovery techniques, including massage, cold water immersion, stretching, and massaging. Significant increase in HRV.
But just because HRV is a useful metric doesn’t mean that “recovery” or “readiness” scores are also useful. HRV is a component of these scores, but they are often proprietary and companies do not share how they are calculated. “We can’t get inside them to understand how they were developed,” says David Scott. “The truth is there isn’t a lot of evidence behind them that they can actually predict whether we’re ready for peak performance.”
This leads us to perhaps the most fascinating data point on recovery: a systematic review Deakin University researchers are examining the measure that best reveals how tired an athlete is and how well they are recovering.
Researchers looked at heart rate, blood markers, oxygen consumption, HRV and many other measurements. But one surprising metric trumped them all: How stressed or recovered athletes felt..
“Your best indicator is how you feel physically and mentally,” says Scott. “Don’t get too dependent or lost in these metrics.”
Recovery: what really matters
AIS’s McKune advocates thinking of your recovery strategies like a pyramid. At the bottom are the foundations that everyone needs to lay correctly.
“It’s not going to be anything special,” McKune says. Make sure you get seven to nine hours of sleep a night. Refuel with carbohydrates and rebuild with protein. Replace lost fluids.
As they move toward that point, “they become more specific to the preferences of individual athletes,” McKune says. The kind of stuff Stefanos Sifandos has in P3.
Sifandos thinks sauna, red light therapy and hyperbaric oxygen play a role, but ultimately agrees with McKune.
The basics are very important: sleep, hydration, light exercise. “Most people want hacks,” says Stefanos, “but the real recovery is incredibly simple.”
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