Smartphones can now give amateurs technical help and analysis of the kind that, until recently, had only been available to the professionalsMY GOLF swing is wonky. The backswing isn't so bad, I suppose, but it's my follow-through: it's all over the place.
At least, that's the painful feedback I've gleaned from SwingReader - an iPhone app that uses video to help pinpoint flaws in the average golfer's game. Alongside runners' apps, it's just one of the new ways amateurs can now get technical help and analysis of the kind that, until recently, had only been available to the professionals.
SwingReader, from start-up tech firm UberSense, lets amateurs load videos of their own swing and compare it with footage of professional golfers to see where they are going wrong. In December, computer vision algorithms will be added to the app so that individual objects in the frame - such as the golf club's head - are tracked automatically.
"You can identify objects within the video without the user having to wear sensor nodes on their body," says the firm's Amit Jardosh. "This has never been done on a mobile phone before."
Smartphone sensor packages - which increasingly include an accelerometer and gyroscope - mean they can be also be strapped to an athlete and used to record detailed biomechanical data, such as a runner's stride. But carrying out analysis on a cellphone is impractical. "Processing this data chews up a tonne of battery power," says Tristan McNab of Griffith University in Brisbane, Australia.
So McNab is working on an iPhone platform that logs the athlete's movements using the smartphone's built-in sensors but then uploads the data to cloud servers via Wi-Fi for the heavy number-crunching.
Users have an account that allows them to access a suite of analytical tools online. "By offloading calculations to the server, we save the user battery power and they may only need to buy a single app," says McNab.
But all of this data is useless to athletes unless it's delivered in a "reasonable and rational way", says Richard Wheater, head of coaching for England Athletics.
For example, an amateur runner may not know what to do with a system that says "your foot is pronating 32 degrees when it hits the ground". Simpler instructions like "try lifting your knees" could be more helpful.
"You've got to remember it's the quality of interpretation that counts," he says.
For this reason, UberSense's product still requires someone to view the video frames and make recommendations to the athlete.
Beyond apps, researchers are also turning to devices known as inertial measurement units (IMUs). Michael Lapinski at the Massachusetts Institute of Technology in Cambridge has developed the sportSemble system, which uses IMUs to analyse how baseball pitchers throw the ball. Each unit contains an accelerometer, gyroscope and magnetometer to measure strength and direction of magnetic field, similar to those found in an iPhone. One is attached to the pitcher's hand, wrist, upper arm, chest and waist.
IMUs are much more sensitive than the iPhone's sensors - the IMU accelerometers can record forces up to 120 g created as an athlete goes through his pitching motion, for example. Lapinski is working with a Major League Baseball team (he won't say which one) to catalogue how their star pitchers manage to dominate the league's best hitters. Such data could also help amateur players improve their game.
IMUs could even help those looking to improve their regular jog. Christina Stohrmann at the Swiss Federal Institute of Technology (ETH) in Zurich has attached sensors to a runner's hip and foot to distinguish between the contrasting running styles of novices and those more experienced. Currently, optical tracking is used to monitor a runner's gait. This requires expensive equipment and limits the analysis to an indoor treadmill. "Even professional athletes don't have regular access to these systems, they are so expensive," says Stohrmann.
Data collected from the sensor units picks out how each runner's foot hits the floor, whether it is toe first (better for sprinters) or a mid-foot stride (for long-distance runners). It also measures heel lift and length of sole contact with the ground.
Stohrmann says her system, presented at the Ubicomp conference in Beijing, China, in September, could be used like an advanced version of pedometer kit Nike+ to give biomechanical feedback and tips to amateur runners via a smartphone app.
Andy Harland, head of the sports technology research group at Loughborough University, UK, says the increase in performance from such devices will likely be more dramatic in novice athletes than professionals. "Some kind of law of diminishing returns would apply here," he says. "Some basic intervention is likely to allow a novice to develop a golf swing or running style to a reasonable level fairly quickly. However, much more sophisticated analysis methods and interpretation would be needed to allow an elite athlete to improve by a much smaller amount."
In other words, all the fancy new measurements probably won't make you as good as a pro. But they should at least level the playing field.
Amateurs already have ways to get simple data about their training.
One of the first such products was Nike+, a pedometer that is attached to your training shoe and syncs data with your iPod. Earlier this year Nike teamed up with satnav company TomTom to create a GPS-enabled watch, and Garmin recently launched a competing device, Garmin Fit.
Team sports are catered for too. Adidas has just unveiled a new football boot that contains a sensor which detects how much ground the footballer is covering, their direction, and how often they sprint. Wahoo Fitness uses pedometers and heart rate monitors that link with an iPhone app to log progress while running or cycling.