Legendary golf instructor Harvey Penick compared the sequence of a golf swing to that of lopping off the heads of dandelions with a weed cutter to convey the right sensation to his students.

Many of us still rely on conjuring up mental images of swinging buckets of water or clipping weeds to train our bodies to produce the best golf swings of which we are physically capable. But whether or not we flush it every time, or have those rounds where we’re just flushing it away, it’s important to know what we’re doing correctly or incorrectly in order to play our best golf more often.

The Golf MTRx application for iPhone, by Zeroline Golf, is a portable and sophisticated tool that records your swing and translates the kinematic sequence of your pelvis into data you can use to better understand how your body functions when it swings a club.

Overview

The Golf MTRx app is the first mobile technology that measures the efficiency of a golfer’s pelvis to generate a powerful and repeatable swing. Your individual kinematic signature is compared to pro tour averages and produces a score (a maximum of 100) based on four components: acceleration, deceleration, peak time and speed.

As described on Zeroline Golf’s website, the four factors that promote an efficient use of  the pelvis are:

1. Acceleration: A golfer must have proper acceleration to achieve the necessary deceleration as the upper body begins to fire. Acceleration should ideally be about 2.0 kd/s/s (thousand degrees per second per second) and will show on the Golf MTRx chart as a good steady steep slope going from zero to peak speed.
2. Deceleration: Happens when the torso, arms and club start to engage on the downswing. The upper body puts pressure on the lower body and the pelvis will stabilize as the upper body fires. The pelvis should decelerate at the same rate or greater than the acceleration. Deceleration is necessary to achieve good peak time.
3. Peak Time: The place in time that the pelvis reaches peak speed on the downswing. Peak time needs proper acceleration and deceleration. The “ideal” peak time is about 60 percent through the down swing to impact — that’s measured in time, not degrees of rotation. Golfers need good peak time for the segments above to rip it.
4. Speed: Measured in degrees per second. Speed is an important component, but it can often be a side effect of the categories listed above. Speed matters most early in the kinetic chain.

In layman’s terms, the Golf MTRx app decodes the conditions necessary for your body to produce good shots, and give golfers a tool they can use to correct their physical mistakes on bad shots. It’s what Zeroline Golf Co-Founder and Chief Technology Officer Steve Blake calls “measuring a feel,” or giving golfers specific information about what they did or didn’t do during a swing.

“From my software experience, I knew the iPhone had motion sensors, a microphone and great graphics,” said Blake. “We concluded that having an app that could measure hip movement would be possible, and that we could develop it into a great training aid for coaches and golfers … We also thought it would be helpful for a golfer to be able to save information from that ideal swing to serve as a baseline from which to compare and improve.”

The Technology

The Golf MTRx app underwent rigorous field testing with golfers of various levels and abilities prior to its December 2012 launch. It was also introduced to coaches from a wide variety of philosophies and backgrounds.

“The beta testing included the participation of coaches, and we think this has impacted the positive reaction from the coaching community — even from instructors who are resistant to the use of technology in golf,” Blake said.

In terms of the data itself, Blake built a wooden swing testing device that allowed him set exact turn angles and impact positions, which aided him in validating the consistency of the reported readings. The swing recognition algorithm was tested against thousands of swings to eliminate false positives. Independent tests were performed against K-VEST and AMM (Advanced Motion Measurement Golf Swing Analysis Training System) with very good results.

The ideal numbers that all users of Golf MTRx ultimately compared themselves to came from research and conversations Zeroline Golf had with experts at Titlelist Performance Institute and K-VEST. The tour pro averages for acceleration, deceleration and speed are modeled after a male swinging a 5-iron.

The Golf MTRx app can be used with any club in the bag, but users will notice differences in their score and variations for acceleration, deceleration and speed. My own experience with the app reveled that my acceleration and speed increased as I went from wedges to woods.

Ideally, peak time should stay the same indicating that the golfer is stabilizing properly for all of his or her clubs. In my case, the peak time varied from club to club, which helped me realize that my swing isn’t as consistent as I would like it to be throughout the bag. Chances are, a lot of golfers will find distinguishable quirks in their swings. The Golf MTRx app isn’t designed to necessarily fix issues in your swing, but it can go a long way in helping to identify areas to improve upon.

Pros

First and foremost, the Golf MTRx app is easy to use. A profile takes seconds to create and the app allows you to create multiple profiles — useful if you and a friend want to take turns recording your swings and compare results.

Once your profile has been setup, click the record and analyze button, followed by the “Start Recording” button at the bottom of the application screen. At this point you’re ready to secure your iPhone to your hip. Zeroline Golf recommends that you fasten it under your belt with the iPhone top down. As far as accurate measurement goes, I found the app performed best when my iPhone was held snug against my hip or behind me near the base of my spine.

You can make practice swings in record mode. The Golf MTRx app will only record your swing when pronounced contact is made with either turf or ball. If you have the volume turned up (highly recommended), the app will emit a “ping” when your swing has been successfully recorded. Double tap the “stop” button and you’re ready to review your kinematic swing sequence and your Golf MTRx score.

The swing analysis screen will provides charts, animations and recommended drills to help you make sense of all the data. The score tab will provide you with a quick snapshot of your performance for all four components of your MTRx score: acceleration, deceleration, peak time and speed. The current version of the app is limited to comparing your values to those of a tour pro. A planned update to the app will allow a user to not only set their baseline swing, but to adjust the values up or down for acceleration, deceleration and speed — essentially allowing yourself to set your own bar for peak performance.

Undoubtedly, gear heads will find plenty of useful metrics to dive into within the MTRx and Chart tabs of the application. The MTRx tab allows you to play an animation of your swing sequence so that you can see how your pelvis is storing and releasing energy through impact. The Chart complements the MTRx tab by plotting your sequence as a bar chart. Both tabs tell you how much your hips are rotating during the backswing, impact and follow through.

Zeroline Golf has placed a lot of attention upon the four pivotal components that make up a golfer’s MTRx score, but a lot less has been said about hip rotation and tempo. Apparently, I wasn’t the only user of the app who found the information about hip rotation confusing. The latest version of the app (v. 1.5) has added an assessment feature that compares your hip rotation in the backswing to the recommended range which is -25 to -45 degrees. The recommended range for impact is said to be 15 to 40 degrees.

“Too little rotation indicates poor separation of hips and shoulders and results in loss of power,” says Blake. “Too much rotation at impact is hard to quantify; it is up to the individual’s capability. Rory McIlroy has his hips at 62 degrees at impact. I’m lucky to get to 40 degrees.”

The best way to get a better understanding of the role hip rotation plays in your own kinematic sequence is to record multiple swings and experiment with the intended result. Likewise, tempo also plays a role in bio-mechanic efficiency, but there isn’t enough data on the subject to declare an ideal measurement.

“Studies like Tour Tempo measure the club tempo, not that of the hips,” says Blake. “As a result, we do not place a great emphasis on tempo. The app will report the numbers regardless of the tempo. This is another data point that varies depending on a golfer’s physical capabilities and limitations. In my own experiments, I find a slower tempo works better for me, but I’m 62. We have seen lots of young golfers with quick tempos who crush the ball.”

The most underrated feature of all is that the Golf MTRx app is swing agnostic. It doesn’t care if you are a practitioner of Stack and Tilt or a more traditional approach; whether your swing tempo is reminiscent of Rickie Fowler or Ai Miyazato.

Cons

If you are an owner of an Android-powered phone, consider yourself out of luck. The Golf MTRx app is available for iPhone only and the differences in hardware among Android devices ensure that porting the app will remain a less than straightforward process. An Android-specific version remains high on Zeroline Golf’s to do list, but as of right now there is no timetable for releasing one.

Another major complaint heard among some users is about the price. Golf MTRx retails for $29.99 in the App Store — comparatively more expensive than most iPhone applications. If you’re on the fence about the price, Zeroline Golf will be releasing a light version of the app called Golf MTRx LT that will retail for $9.99. The LT edition has many of the same features but will only allow a golfer to create a single profile and record up to 18 swings at a time. It is designed with the novice to intermediate golfer in mind.

Serious golfers who are obsessed about their training and their gear aren’t going to be put off by the price for the full app, which delivers a wealth of data at a fraction of the cost of professional swing analyzers. Kudos to the Zeroline Golf team for bringing high performance and accurate motion analysis data to the masses in a handy mobile application. Still, fans of the app shouldn’t lead themselves to believe they are using a tool on par with K-VEST which uses sensors on the pelvis, upper body and lead wrist to capture 2D video and 3D motion. Golf MTRx is limited to a single sensor and cannot relay any information about the upper body or club head.

Truth be told, a lot of golfers are better off with less information at their fingertips. Even with some obvious limitations, the Golf MTRx app might be too overwhelming for some users. What does it really mean to the average golfer if their peak time falls short of the gold standard? Are certain numbers more important to hit than others?

Credit Zeroline Golf for thinking strategically ahead about those of us who may go plummeting down the rabbit hole of misinformation and confusion. Its website now features a directory with a growing list of coaches including GolfWRX frequent contributors, Monte Sheinblum and Dan Carraher. Instructors like Carraher who have openly endorsed the app view it for what it is – a training aid that complements their teaching approach.

“Because the app like any tool, similar to a mirror or camera, is useless without the proper knowledge,” Carraher said. “Students tend to see the same success rate regardless of using it or not. Success is usually based on the work ethic and aptitude for repetitive practice more so than any tool. But I also feel as long as the student knows what to look for more information isn’t a bad thing. It’s not knowing what is relevant and trying to play connect the dots that deters progress.”

The Bottom Line

The Golf MTRx application earns high marks for innovation, ease of use and value. Whether or not golfers can stand to benefit from charting their swings comes down to a personal choice. We have all known golfers, including some at the very highest professional level, who have fallen in love with statistics and are fixated on improving their swings to the detriment of all other components that make up the game of golf.

“If you try to swing to a picture on camera or swing to make the numbers [look] good you are losing sight of what is important — the actual causes and hitting the golf ball at a target,” Carraher said. “Playing golf is more than just a pretty swing or good numbers on a screen, be it TrackMan or Golf MTRx. Golf is played in ever- changing imperfect conditions on an imperfect surface by human beings. It’s more about learning your tendencies and planning around them, than trying to eliminate every bad tendency and hit perfect shots.”

Perhaps it goes without saying, but just like those of us who prefer not to dissect themselves on video, there’s a segment of golfers who are best left to using their imagination and creativity to fuel their swings and fix any ailments. Golf MTRx would probably feel right at home for detail-oriented strategists like Nick Faldo and Stacy Lewis, but not so much for shot-making savants like Bubba Watson or the late Seve Ballesteros.

Most of us fall in line somewhere in between these opposite extremes and take on multiple, sometimes incompatible approaches to get better. I don’t find it all odd to fixate my mind on an image of a swinging bucket if I know it helps me groove a smoother takeaway, while I rely on an app to monitor my hip rotation and peak time. Golf MTRx doesn’t negate the respected teachings of a Harvey Penick; if anything, it supports his theories with science.

“We were concerned that some coaches would see the emergence of this technology as a threat to their livelihood, but the instructors who have used Golf MTRx have reported that it has supplemented their instruction and is another effective tool they can use with students,” Blake said. “Some have said that the app has allowed them to convince students of points they have been making for months, since there is concrete data that the coach can show them. We also hope that Golf MTRx will serve as an enabler of biomechanics by putting low cost technology in the reach of many golfers. If ‘Joe Golfer’ is able to ‘measure a feel’ and understand what his body is doing when he hits that great shot, we believe that Golf MTRx will have served its purpose.”