Fitness
Six ways your smartwatch is lying to you, according to science
You check your smartwatch after a run. Your fitness score has dropped. You’ve burnt hardly any calories. Your recovery score is really low. It’s telling you to take the next 72 hours off exercise.
The worst bit? The whole run felt amazing.
So why is your watch telling you the opposite?
Ultimately, it’s because smartwatches and other fitness trackers aren’t always accurate.
Smartwatches can shape how you exercise
Using wearable fitness technology, such as smartwatches, has been one of the top fitness trends for close to a decade. Millions of people around the world use them daily.
These devices shape how people think about health and exercise. For example, they provide data about how many calories you’ve burnt, how fit you are, how recovered you are after exercise, and whether you’re ready to exercise again.
But your smartwatch doesn’t measure most of these metrics directly. Instead, many common metrics are estimates. In other words, they’re not as accurate as you might think.
1. Calories burned
Calorie tracking is one of the most popular features on smartwatches. However, the accuracy leaves a lot to be desired.
Wearable devices can under- or overestimate energy expenditure (often expressed as calories burned) by more than 20 per cent. These errors also vary between activities. For example, strength training, cycling and high-intensity interval training can lead to even larger errors.
This matters because people often use these numbers to guide how much they eat.
For example, if your watch overestimates calories burned, you might think you need to eat more food than you really need, which could result in weight gain. Conversely, if your watch underestimates calories burned, it could lead you to under-eat, negatively impacting your exercise performance.
2. Step counts
Step counts are a great way to measure general physical activity, but wearables don’t capture them perfectly.
Smartwatches can under-count steps by about 10 per cent under normal exercise conditions. Activities such as pushing a pram, carrying weights, or walking with limited arm swing likely make step counts less accurate, as smartwatches rely on arm movement to register steps.
For most people, this isn’t a major problem, and step counts are still useful for tracking general activity levels. But view them as a guide, rather than a precise measure.
3. Heart rate
Smartwatches estimate your heart rate using sensors that measure changes in blood flow through the veins in your wrist.
This method is accurate at rest or low intensities, but gets less accurate as you increase exercise intensity.
Arm movement, sweat, skin tone and how tightly you wear the watch can also impact the heart rate measure it spits out. This means the accuracy can vary between people.
This can be problematic for people who use heart rate zones to guide their training, as small errors can lead to training at the wrong intensity.
4. Sleep tracking
Almost every smartwatch on the market gives you a “sleep score” and breaks your night into stages of light, deep and REM sleep.
The gold standard for measuring sleep is polysomnography. This is a lab-based test that records brain activity. But smartwatches estimate sleep using movement and heart rate.
This means they can detect when you’re asleep or awake reasonably well. But they are much less accurate at identifying sleep stages.
So even if your watch says you had “poor deep sleep”, this may not be the case.
5. Recovery scores
Most smartwatches track heart rate variability and use this, with your sleep score, to create a “readiness” or “recovery” score.
Heart rate variability reflects how your body responds to stress. In the lab it is measured using an electrocardiogram. But smartwatches estimate it using wrist-based sensors, which are much more prone to measurement errors.
This means most recovery metrics are based on two inaccurate measures (heart rate variability and sleep quality). This results in a metric that may not meaningfully reflect your recovery.
As a result, if your watch says you’re not recovered, you might skip training — even if you feel good (and are actually good to go).
6. VO₂max
Most devices estimate your VO₂max — which indicates your maximal fitness. It’s the maximum amount of oxygen your body can use during exercise.
The best way to measure VO₂max involves wearing a mask to analyse the amount of oxygen you breathe in and out, to determine how much oxygen you’re using to create energy.
But your watch cannot measure oxygen use. It estimates it based on your heart rate and movement.
But smartwatches tend to overestimate VO₂max in less active people and underestimate VO₂max in fitter ones.
This means the number on your watch may not reflect your true fitness.
What should you do?
While the data from your smartwatch is prone to errors, that doesn’t mean it is completely worthless.
These devices still offer a way to help you track general trends over time, but you should not pay attention to daily fluctuations or specific numbers.
It’s also important you pay attention to how you feel, how you perform and how you recover. This is likely to give you even more insight than what your smartwatch says.
Hunter Bennett is a lecturer in exercise science at Adelaide University. This piece first appeared on The Conversation.
Fitness
The NHS has reignited the hybrid working debate – but WFH isn’t the health risk, this is
The latest NHS exercise guidance reinforces what we’ve been preaching for years: hitting that 150-minute weekly movement target isn’t necessarily a get-out-of-jail-free card. It states that prolonged sedentary time is independently harmful, even for those of us who diligently carve out time for the gym. Verbatim, it says ‘prolonged sitting is harmful, even in people who achieve the recommended levels of moderate to vigorous physical activity’.
Chief Medical Officer Professor Sir Chris Whitty has been especially vocal about how detrimental it could be, highlighting hybrid working as a potential health hazard. ‘Without wanting to exaggerate, I think it’s important people think through, for example, hybrid working means quite a lot of people could very easily do very little other than leave their homes, where previously people would be routinely going to work, and that often meant at least some physical [activity],’ he said at a briefing.
I understand his logic, but it’s pretty reductive. Working from home isn’t the villain here – working from one chair is.
When we label remote work as “bad for your health”, we risk throwing the baby out with the bath water. In reality, for many – certainly the whole of the Women’s Health office, but also my less-fitness-conscious sister and stepdad, plus my entire friendship group – working from home often means being more active. It means more time to fit in a lunchtime run, to get some steps in before work, or to run some errands on a quick break.
On the other hand, plenty of office workers are more sedentary than they are at home. They sit at a desk for nine hours straight before driving home, whether to be seen to work tirelessly in front of their manager, or simply because they’re pulled from pillar to post in an office setting. For those who do have an office commute, eliminating that often stressful period of the day allows for better sleep, and more time for the movement breaks we need to break up the dreaded sedentary time. Not to mention that many commutes are almost entirely sedentary on a train/tube/bus.
The potential problem, the advice suggests, is the lack of incidental movement – the walk to the train, the stroll to a meeting room, or heading out for lunch – that’s naturally baked into your day when you’re in the “official” office. Without a commute or a day in the office, the onus is on you to manufacture movement in.
Without sounding evangelical, I’ve made this a non-negotiable part of my day. On WFH days, I work out or walk every single morning before I log on, and walk again every evening, even if just a lap around the block. During the day, I have a personal rule: if I’m downstairs, I use the upstairs toilet (and vice versa). Sounds excessive, but it forces me to activate my muscles and add to my step count every few hours.
Beyond that, the options are endless if you’re intentional. Use a standing desk or put your laptop on a kitchen worktop during calls. Take every phone meeting on foot, pacing your hallway if necessary. Set a timer to stand up every 30 mins to stretch, grab a glass of water, or do a quick load of laundry.
We don’t need to return to the office to be healthy; we need to bring movement back into our homes. The goal: to stop being professional sitters.
As Women’s Health UK’s fitness director and a qualified Pilates and yoga instructor, Bridie Wilkins has been passionately reporting on exercise, health and nutrition since the start of her decade-long career in journalism.
After earning a first-class degree in journalism and NCTJ accreditation, she secured her first role at Look Magazine, where she launched the magazine’s health and fitness column, Look Fit, before going on to become Health and Fitness writer at HELLO!
Since, she has written for Stylist, Glamour, Cosmopolitan, Marie Claire, Elle, The Metro, Runner’s World and Red. Today, she oversees all fitness content across Women’s Health online and in print, spearheading leading cross-platform franchises, such as ‘Fit At Any Age’, which showcases the women proving that age is no barrier to exercise.
She has also represented the brand on BBC Radio London, plus various podcasts and Substacks – all with the aim to encourage more women to exercise and show them how. Outside of work, find her trying the latest Pilates studio, testing her VO2 max for fun (TY, Oura), or posting workouts on Instagram.
Fitness
A Strength Coach Says These Two Exercises Are All You Need to Build Stronger Shoulders
If you ask anyone on the gym floor how to grow a bigger set of shoulders, you’ll probably find that no two answers are the same. In between front raises, upright rows, machine presses and cable raises, shoulder day can quickly become a long list of exercises.
However, fitness creator and coach Eric Evans, also known on social media as Average to Jacked, thinks most lifters are overcomplicating things. He says that if he had to start from scratch after over a decade of training, he’d strip his shoulder workouts back to just two simple moves.
‘If I had to start over today, I’d build my shoulders with just two movements: a lateral raise and also a rear delt fly,’ he explains.
According to Evans, the reason for this isn’t because those exact exercises are magic, but because they work the correct movement pattern for the muscle.
‘Your body doesn’t know the name of the exercise you’re doing,’ he argues. ‘It really only knows the fundamental movement pattern you’re asking it to perform and also the amount of tension you’re placing on the muscle.’
So, you don’t have to perform cable lateral raises if your gym only has dumbbells, or use a reverse pec deck if you’d rather do bent-over rear delt flyes. As long as you’re training the same movement pattern and progressing the move with intensity or volume, you’ll achieve a similar result.
According to the coach, lateral raises deserve a place in your programme because they primarily target the side delts, helping create broader-looking shoulders and a more pronounced ‘V-taper’. Rear delt flyes train the back of the shoulders to create a rounder, more 3D physique.
‘I’m not including anything for the front delts, and that’s intentional,’ he says. ‘Your front delts are already heavily involved every time you do pressing exercises for your chest.’
For most lifters already bench pressing, incline pressing or overhead pressing regularly, he argues the side and rear delts are more likely to be the limiting factor.
‘I don’t think the front delts are what’s holding their shoulders back. I think it’s the side and rear delts,’ he adds.
He recommends focusing on controlling every rep, and avoiding using momentum to swing the weight. He also suggests working in the 8-15 rep range, adding reps until you reach the top of the range before increasing the load and repeating the process – also known as progressive overload.
‘You definitely don’t need to hit your shoulders from 10 different angles,’ he says. ‘You just need to consistently train these two movement patterns, push them hard and then gradually get stronger over time.’
The Bottom Line
Research suggests muscle growth is driven more by sufficient training volume, progressive overload and proximity to failure than by constantly changing exercises and programme hopping. In fact, that could hinder it. So if your shoulder workouts have become jam-packed with unnecessary variations, simplifying your approach may be exactly what helps you make more consistent progress in the long term.
If there’s one thing Kori Sampson knows, it’s how to optimise your body composition for performance. To tap into his knowledge as an elite athlete and coach, we asked him to create a 4-week plan to help you move faster, recover quicker and keep pushing when the fatigue sets in – all while improving your muscle-to-fat ratio.
Ready to build muscle, burn fat and come out the other side looking, feeling and performing better? Click here to get 14 days of free access to the plan via the Men’s Health app.
Fitness
80-year-old fitness icon Joan MacDonald reveals her simple exercise for a stronger, more stable core
Joan MacDonald didn’t enter a gym until she was 70. Really. Since then, the 80-year-old has transformed her health by losing three stone and building significant muscle, and now coaches other women through her training platform, Train With Joan, which she launched to help others boost their fitness at any age.
The premise of her app is simple: minimal-equipment workouts built around no-fuss, effective exercises that can be done anywhere. One ‘powerful core and stability exercise’ she swears by is alternating bodyweight clock taps. ‘This movement helps strengthen the muscles that keep you stable, balanced and moving well as you age,’ Joan explains.
Bodyweight clock taps benefits
Think they look too simple? That’s the point. Joan is adamant that ‘You don’t need complicated workouts to start getting stronger. Sometimes the most effective movements are the simple ones you do consistently.’
According to Joan, regularly performing bodyweight clock taps help:
- ‘Strengthen your core which supports your spine and reduces strain on your lower back.
- ‘Improve balance and coordination, helping you stay steady on your feet.
- ‘Increase hip stability, which supports your knees and joints.
- ‘Build functional strength for everyday movements like stepping, turning and reaching.
- ‘Help reduce fall risk by improving control and body awareness’
How to do bodyweight clock taps
Find a demo from Joan above, along with instructions for how to do them with proper form below.
- Stand on one leg with a slight bend in your supporting knee and brace your core.
- Keeping your hips level, reach your free foot forward to lightly tap the floor in front of you (12 o’clock), then return to the centre.
- Continue tapping to different “clock” positions—such as 3, 6 and 9 o’clock—maintaining your balance and control throughout.
- Complete all reps on one leg before switching sides.
Form tip: Move slowly and focus on staying stable. The goal is controlled movement, not how far you can reach.
How many reps and sets to do
Joan shares her advice, according to your fitness level.
- Beginners: ‘3 taps per leg x 8-10 reps’
- Intermediate: ‘3 taps per leg x 10-12 reps’
- Advanced: ‘3 taps per leg x 12-15 reps’
One of our most frequently asked questions here at Women’s Health? How to build muscle and burn fat at the same time. So, we asked superstar trainer Oyinda Okunowo exactly how to do it. In this 4-week plan – created exclusively for Women’s Health COLLECTIVE members – you’ll get the workouts and nutrition guidance needed to help you on your way to better body composition. Tap the link below to unlock 14 days of free access to Oyinda’s plan and start training today.
Get the plan
As Women’s Health UK’s fitness director and a qualified Pilates and yoga instructor, Bridie Wilkins has been passionately reporting on exercise, health and nutrition since the start of her decade-long career in journalism.
After earning a first-class degree in journalism and NCTJ accreditation, she secured her first role at Look Magazine, where she launched the magazine’s health and fitness column, Look Fit, before going on to become Health and Fitness writer at HELLO!
Since, she has written for Stylist, Glamour, Cosmopolitan, Marie Claire, Elle, The Metro, Runner’s World and Red. Today, she oversees all fitness content across Women’s Health online and in print, spearheading leading cross-platform franchises, such as ‘Fit At Any Age’, which showcases the women proving that age is no barrier to exercise.
She has also represented the brand on BBC Radio London, plus various podcasts and Substacks – all with the aim to encourage more women to exercise and show them how. Outside of work, find her trying the latest Pilates studio, testing her VO2 max for fun (TY, Oura), or posting workouts on Instagram.
-
Politics2 minutes agoTrump-aligned House holdouts accused of holding ‘life-saving’ veterans bill ‘hostage’ over SAVE America Act
-
Health9 minutes agoSimple sitting change linked to lower risk of cancer death, study finds
-
Sports11 minutes agoGolf star records lowest round in LPGA major history with astounding performance at Evian Championship
-
Technology17 minutes agoMeta Verified scam threatens Facebook deletion
-
Business24 minutes agoMeta discontinues Instagram feature on new AI image generation tool after Hollywood backlash
-
Entertainment27 minutes agoHuey Lewis details how he ‘can’t enjoy music’ anymore because he is ‘basically deaf’
-
Lifestyle32 minutes agoTwice the stink! Two rare corpse flowers at the Huntington are set to bloom
-
Politics39 minutes agoAssassinations unleashed under Trump haunt Iran war endgame

