The nation’s Christmas stockings bulged with Fitbits, Jawbones and the like, promising to lead us to a leaner, lither and more healthy 2016. The wristbands or widgets, which monitor steps taken, calories burnt, heart rate and even sleep quality are hugely popular, but does the evidence support the hype? The sale of fitness tracking devices has grown exponentially, with sales of a £1.3 billion last year and some analysts predicting a staggering $50 billion by 2019. But recent research suggests that they may not be worth the investment.
Do they work?
If you use a tracker you may recognise the frustration of wearing it for a very active day and having a paltry 2,500 steps registered. Conversely a few drinks and some very active gesticulation when chatting in the pub can give your step count an unwarranted boost. Now research confirms that the devices may be failing in their most fundamental function, accurately measuring physical activity and estimating the amount of energy expended.
Researchers in Japan compared the readings from twelve popular wearable fitness devices with reliable research techniques, in the laboratory and real-life settings to calculate the amount of energy expended.
The measurements differed widely between devices but when compared to lab tests one of the trackers underestimated the calories burned by as many as 270 calories, and others overestimated by as many as 200 calories. With measurement during normal activities, all trackers consistently underestimated the energy expenditure. They speculated that this could be due to battery issues, bathing and swimming or simple inaccuracy and concluded that:
"Most wearable devices do not produce a valid measure of total energy expenditure."
The truth is that measuring absolute energy expenditure accurately is challenging, even in the laboratory setting and the technology is still not advanced enough to get truly reliable results.
Indeed, Michael Joyner, MD, of the Mayo Clinic has gone further and said that:
"There is little evidence that extreme monitoring improves outcomes" or that "these devices are going to motivate long term behaviour change. In many cases, they are high-tech versions of old-school exercise equipment from 'last Christmas' that ends up unused in the garage or basement."
Monitoring and Modification
But is a tracker really just like the abdominizer gathering dust under your bed? Many trainers, doctors and enthusiasts disagree. Although the research seems negative, many people have found a fitness tracker to be beneficial in providing an insight into their activity levels. GP and marathon runner Dr Glynnis Drew told me that although the devices can be flawed they can draw attention to how sedentary our lives really are and how little activity many of us are doing in the course of a normal day.
The devices may also be useful for monitoring trends and tendencies. So, if you notice that you’ve had a lazy day, you may feel motivated to take a walk, or give the lift a miss and take the stairs.
However it’s easy to come unstuck if you rely on the tracker to tell you how much food you can safely eat without gaining or losing wieight. If a device tells you that you’ve burned a few thousand calories more in a week than you really did and you happily chow those calories down, then it’s not difficult to see how the weight can pile on despite your best efforts.
So use your fitness tracker to guide, rather than control what you do and you can achieve greater insight into your activity, your health and your wellbeing.
