Whoop Strap 2.0 review

The Whoop Strap 2.0 is a wearable that aims to encourage athletes of all disciplines to pay greater attention to the relationship between the strain training places on their bodies, and the sleep and rest necessary to recover from it.

This wrist-worn sensor was originally designed for elite athletes; those whose livelihoods depend on hitting their peak when it matters most and remaining durable when play-off time rolls around, year after year.

• Whoop 4.0 review

Now, the same strap worn by LeBron James, Michael Phelps and 23 Rio Olympians is available to everyone. For a premium of $500, anyone can train and recover like a world-beater.

We've been living with the second-gen Whoop for some time now to find out if this grown up Fitbit really does deliver.

Whoop Strap 2.0: Design

Whoop is a pretty unobtrusive wearable device, one of those you don't notice after a while. The elasticated Nanostretch band, which ships with Whoop, is lightweight and comfortable. The company advises that it be worn tight enough to make it difficult to slide your pinky finger underneath. This ensures the sensors don't lose contact with the skin.

The band keeps the footprint small compared to some trackers out there. While this is a plus in most ways, the material is really irritating to wear when soaked in sweat after a heavy workout and after a while it becomes a little grubby.

The same applies to wearing it in the shower. Whoop is waterproof, but dealing with a soaked strap for ages afterwards isn't worth keeping it on for the five minutes you're rinsing off.

Another slight annoyance is that the flexibility of the band means the sensor can get twisted during the night. If the heart rate sensor loses contact with the skin, sleep tracking gets messed up, which has the knock-on effect of skewing your recovery stats too.

There's a Hydroband option available for $15, which I've started using, and that takes care of both problems. It's well worth the investment if you're forking out $500 for the sensor.

Whoop Strap 2.0: Fitness tracking

The simple-looking sensor monitors five key data points. It will continuously track your heart rate as well as your heart rate variability, both vital in charting the 'Day Strain' and your recovery through rest and sleep. There's an accelerometer for tracking movement (not steps), which helps to determine your strain score. It also offers auto-sleep detection and registers disturbances during that sleep. The sensor also tracks ambient skin temperature.

The Whoop sensor takes readings hundreds of times a second and collects almost 100MB of data a day on every user. That's about a full-length music album's worth. Once synced to your mobile device via Bluetooth, all of that is boiled down to three key takeaways: your day strain, recovery score and sleep targets, which are displayed within an app loaded with insights and advice.

Strain

Whoop calculates strain by using your heart rate data to decipher how hard you worked during an activity and on any given day, on a scale of 0-21. Anything below 10 is considered minimal activity, while 18-21 is considered a full-on workout.

In the main, this works well. The day strain score corresponds to how hard you feel like you trained. However, I felt a little robbed when a 5-mile run (littered with walking) earned me 15.7 activity score, while the longer hot yoga class I found much harder overall earned me an 11.4.

Although the calorie output was around the same, the higher strain score was due to spending more time in my max HR zones during the run. Although I was continually challenged in different ways for a longer period of time during the yoga class, my ability to regulate my breathing (hence heart rate) may have lowered the strain score.

I also learned that on days I struggled to get through workouts, it wasn't always due to working particularly hard, but more to do with poor recovery from previous strain.

Recovery

Going the extra mile when the body isn't suitably recovered from fatigue can lead to injury. Everyone knows that, but it can be difficult to quantify how much is too much.

Whoop aims to give athletes the power of knowing when they're overdoing it. It seems to be working too. On average, after four months of wearing Whoop, users report injuries 60% less often.

Before recovery is calculated you're also asked a series of questions. Did you work on a screened device in bed? Did you consume alcohol or caffeine two hours before bed? Did you have sex? All of this goes into calculating your recovery score. The same goes for strain. Once you've entered a workout, you're asked for your perceived level of exertion and performance or whether you had to stop due to fatigue.

Personally, I know I don't get enough sleep. The Whoop sensor compounded that knowledge and helped me realise just how much I'm compromising my physical (and probably mental) potential by regularly staying up for the 4^th quarter, or streaming another Netflix episode while in bed, or having a beer or two during the evenings.

The automatic sleep tracking technology built into Whoop helped to keep me accountable, to motivate me to go to bed earlier and attempt to achieve a higher recovery score, in the same way I push harder to knock off another 100 calories on the treadmill. If you don't get the amount or quality of sleep recommended by the app, your recovery score will be lower and your next day's performance will, in theory, be affected.

However, sleep time and quality is only 33% of the equation when it comes to recovery score. Whoop takes into account your heart rate variability (HRV) and your resting heart rate (RHR). HRV measures the gap between your individual heartbeats while you're resting. The higher the HRV score, the better your body is recovering from fatigue.

Since using Whoop, I've noticed a slightly higher HRV score and a lower RHR, which proves my body is getting better at recovering and I'm getting fitter.

On days when I do too much, that HRV score sinks and drags down my overall recovery, even if I woke up feeling like I had a great night's sleep. The score itself sits in red (0-33%), yellow (34-66%) and green (67%+) zones. If you're in the red zone, it's an idea to take it easy, while the yellow zone indicates you probably won't be performing at your peak.

After a relaxing weekend, I was ready to take on Monday's workout with an 88% recovery score. It gives you greater licence to attack knowing the chances of burnout or injury are greatly lessened.

Of course nutrition and hydration also play a huge role in recovery. I assume that the body's RHR and HRV are affected by both of those metrics, so it would be nice to have integration with a nutrition app. That way users would be able to add their diet, water intake and the times they eat into the recovery equation as well as strain and sleep.

Whoop Strap 2.0: Sleep coaching

Whoop is one of the first wearables to place equal emphasis on recuperation. It's also the first fitness tracker to endorse taking naps to get a head start on sleep.

After you step out of the gym, off the field or the track, Whoop will tell you exactly how much sleep you need to get your body ready to perform or peak tomorrow. The information has resulted in an average of 41 minutes more sleep a night for users.

This functionality goes a step further with the in-app Sleep Coach. Here you can tell Whoop you want to 'get by', 'perform' or 'peak' on the next day, which alters the time you're advised to go to bed. This is great for those athletes who have a big game coming up.

If you don't get the advised amount of sleep, that time will be added to a sleep debt. You can take naps to pay it off. For professional athletes this feature must be great, but most users' inability to take 40 winks between the hours of 9 and 5 might limit the use.

Whoop Strap 2.0: The app

I'm a big fan of what Whoop has done with its companion iOS app (the Android version is coming soon). Your Athlete dashboard offers a snapshot of your daily information. You'll see Day Strain and calories burned, the activities you've logged and the score for each, as well as your recovery score and previous night's sleep. The dashboard also tells you the strap status and battery life remaining.

Swiping from right to left enables to see more detail on each of the key data points. For example, the Strain screen allows you to dig deeper into max heart rate and how it compares to the average of the last two weeks.

Turning the device on its side at any time will load the heart rate graph, augmented by activities and sleep. The main menu enables you to start or add previous activities from a comprehensive list (including sleep).

Push notifications will inform you when an activity or sleep period has been processed as well as when the battery is low and when the strap hasn't synced to the app for a while. That's usually resolved by double tapping the strap.

While the smartphone app is great, the desktop interface is better at enabling you to track data over time. Over the last month, I've cut way down on alcohol consumption. There were two dates where my resting heart rate spiked during the month. I was battling a hangover and did not exercise on either of them. When armed with startling data like that, it's little wonder that Whoop says alcohol consumption before bed is down an average of 79% for users.

Whoop Strap 2.0: Battery life

If you have to remove a health tracker to charge it, then you're denying it the opportunity to do its job. Whoop preaches that you're an athlete for 24 hours a day, not just during the time you're exercising or competing. It pushes the idea that every choice you make counts, so this device needs to be on your wrist around the clock.

Thankfully you don't have to take it off at all. It is charged by a slide-on battery pack, which itself charged separately via micro USB. You wear the battery until the strap is fully replenished, which takes about 90 minutes.

There's no display on the Whoop sensor, but tapping the band activates up to three LEDs indicating remaining battery life. You can check on the status using the app at any time, and you'll also get an app notification when it falls below 10%.

Whoop's advertised battery life is 36 hours, which is a reliable, if slightly conservative, estimate. If I charge the battery until lunchtime on Monday, it keeps me going until first thing Wednesday morning.

Whoop Strap 2.0: Did it work?

I must admit, as a recreational fitness enthusiast, the insights provided by Whoop were often a little bit above my pay grade. I never need to peak for a race or a game, for example. However, this doesn't mean I haven't gleaned a wealth of valuable insights. Now, having used Whoop for over a month, I really don't want to be without it.

Of course, there are more affordable trackers out there that can conceivably suit my needs, but I'd rather drop $500 on this than, say, $150 on a device geared towards January gym warriors focused on upping their step count (Whoop doesn't even bother with steps).

As a result of wearing Whoop I'm more conscious of how hard I train on consecutive days and I'm more liable to push myself when given the (literal) green light by my recovery score.

I have a better understanding of why I'm feeling sore or overtired, and I'm doing a better job of getting to bed earlier and lessening alcohol consumption. These are habits I want to continue and I know Whoop would be a worthy investment in my overall health and wellness.

By providing me with actionable knowledge, it's a device that has pushed me to make changes that have made a difference; changes I feel are sustainable.

For me, that's the difference between Whoop and every other wearable I've ever tested.