Analyzing your body in real time is the next frontier in running technology, with the power to permanently transform training. And the first generation is already here.

Run technology in 2015 has a major deficiency: The most popular training metrics don’t actually measure your fitness or technique—the crucial factors that determine performance. There is still no way to track most of what the body is actually doing. GPS-based speed is an incredibly valuable training tool and modern watches provide exceptionally accurate data, but a slight grade can turn a runner’s easy pace into full-blown race effort. Heart rate provides useful insights into fatigue and workload, but changes in pulse are loosely linked to intensity. And real-time stride efficiency analysis is in its infancy.

In other words, popular training tools are all substitutes for the information with the potential to make training as precise as possible. A new wave of running tech has emerged that eschews proxy metrics for figures that directly quantify specifically what’s happening in a runner’s body while running. Power meters and wearable lactate meters will eventually allow all runners to train or race at the precise effort level regardless of experience. The biggest benefit? Ultimately, it could mean a drop in injury rates as data collected from stride monitors reveals the true cause of many of the injuries plaguing runners today. As technology continues to advance, today’s popular running bugaboos will become a thing of the past.

Running Tech 1.0

Polar launched the first widely available heart rate monitor for athletes in 1982. The idea was to track effort by reading pulse rate. The thinking went like this: If a person’s heart beats faster, his or her cardiovascular effort level is likely to be higher. This is partially true. While there is a strong link between heart rate and intensity, a slew of other factors—fitness, biomechanics, caffeine, sleep, hydration—influence heart rate. While the monitors themselves are far superior today compared to early-’80s hardware, the gap between heart rate and effort level cannot be overcome. The metric is innately limited. GPS is another substitute for directly measuring running effort; there will always be a gap between speed and intensity level. There are better options.

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Exercise physiology researchers had already developed more accurate ways to measure running effort way before Polar released its first heart rate monitor. In 1959, German physiologist Wildor Hollman demonstrated that the quantity of oxygen consumed and concentration of lactate in an athlete’s blood can each reliably indicate effort level. Five years later, American researcher Karlman Wasserman coined the term “anaerobic threshold” and popularized the methods used by Hollman stateside*. The machinery for these tests was bulky, invasive and limited to the laboratory. Most exercise physiology facilities in universities and hospitals now have the equipment—but it’s still clunky and no less intrusive, involving repeated needle pricks or running with a gas mask. A number of entrepreneurial engineers are for the first time approaching solutions to generate equally reliable data about the body’s direct response to running for use on roads and trails.

The Car Key-Size Threshold Tester

For performance-oriented endurance athletes, the blood lactate test is the gold standard for setting training intensity levels. In this test, the subject runs at progressively increasing intensity levels while wearing a heart rate monitor, stepping up the pace every three minutes. Toward the end of each level, a technician pricks the subject’s finger and a device reads the blood’s concentration of lactate. The test continues until the subject can run no longer. This test establishes the most accurate set of training zones possible, but the process is cumbersome and expensive ($150 for a single test), and still relies on heart rate or speed for the athlete to find those zones.

Startup company BSX Athletics has created a device about the size of an electronic car key to continuously read blood lactate while running without repeated stabbing. By shining near-infrared light through the skin and into a muscle, BSX’s Insight ($300, reads changes in blood oxygenation levels in the calf muscle. The portable featherweight device is held against the muscle by a compression sleeve and can be worn indoors or out, under any conditions. It can sync with phones and, in the very near future, select training watches.

Some of running’s most scientifically fluent coaches are taking notice. “It would give us not just an idea of what the heart is doing, it tells how hard the body and the muscles are actually working,” says Steve Magness, the University of Houston’s cross-country coach and the author of “The Science of Running: How to find your limit and train to maximize your performance.”

After testing 237 subjects, BSX found 90 to 97 percent accuracy to laboratory lactate tests. But even once perfected, real-time lactate meters may have limitations. For lactate numbers to change dramatically, a person must be going hard, so this device is most useful when running hard or to set accurate speed or heart rate training zones.

Power to the People

An athlete’s total energy output can be quantified with a single number: Power. The definition used in high school physics classes translates well to running: Power = Mass x Acceleration. Every time a runner’s foot contacts the ground, his or her speed slows. Then through the planted stage of a stride, the runner accelerates both vertically and horizontally, and eventually pops off the ground. The more deceleration, the more power must be generated to reaccelerate. Applying more power or reducing these decelerations are two ways to run faster.

In other words, power, measured in wattage, directly spells out how hard a runner is going stride by stride. Until now, there has been no way to measuring running power, in a lab or outdoors. Danny Abshire, the co-founder of Newton Running and one of the most influential thinkers on running form, is excited about the potential impact of a power meter for running. “Running with a power meter gives you an ability to be realistic about how much energy you’re putting out,” says Abshire. “Because perceived effort versus what’s real are always different things.” A running power meter would show instantaneously how hard a person is working. Power meters have already revolutionized cycling, and, for the first time, engineers are making real progress toward quantifying this elusive metric for runners.

Robert Dick, Ph.D., an electrical engineering and computer science professor at the University of Michigan, has developed a running power meter through a start-up he founded called Athlete Architect. Cycling power meters directly measure the force and speed applied to the bike—Dick has another strategy to create a similar device for runners. By measuring the changes in speed to a runner’s body weight, along with incline, Dick is able to calculate the amount of energy used to repeatedly accelerate with each stride. Stryd ($149.95,, Athlete Architect’s device, is a hip-mounted pod that uses accelerometers, an incline sensor and complex algorithms to determine how much power is required to move a runner. A second pod mounted to the shoe records more stride data. Runners can set intensity zones, just like heart rate, based on wattage numbers and track this number on a watch to stay at the exact right intensity. Seeing a number that quantifies immediate effort can help runners learn to pace properly over any terrain.

Dick compared Stryd’s accuracy against two established laboratory measures and found a 10 percent range of error. While Stryd is an impressive step toward directly measuring a runner’s effort level, a 10 percent discrepancy is sizeable. A runner’s stride is a complex mix of two different energy sources: The first is metabolic: energy produced by the muscles. Fitness limits the quantity. The second is elastic energy. Burning calf and quad muscles give the impression that these muscle groups are doing all the work in a running stride, but in reality connective tissue including the Achilles tendon is stretching and recoiling like a series of springs to re-inject massive amounts of energy into a stride. Because of this dependence on elastic energy return, a perfectly even stride is not necessarily the most efficient way to run. The second stage of development for Stryd will focus on improving the accuracy of Stryd’s power numbers incorporating gait data collected from a footpod.

The Form Factor

Understanding stride mechanics while running is another area exploding with interest and new tech. For all the talk about running technique, the most powerful widely available gait analysis tool has been the cell phone video camera. Examining a runner’s gait on video is useful, but only tells a portion of the story and provides no information when an athlete needs it most—during a run.

Now, a handful of companies are trying to arm runners with information about their stride during workouts. Sensoria, a start-up founded by a pair of Microsoft alumni, created an instrumented sock with conductive yarns that records previously unavailable biomechanical data including foot strike location (heel vs. mid-foot vs. toe), impact force and ground contact time. The runScribe Pro, a device from another sports tech startup, is a foot pod that collects a multitude of data on the movement of the foot and ankle during a stride, quantifying a host of attributes such as pronation. These data collected from either device are displayed through an app in real time so a runner can check his or her numbers during a run and adjust accordingly.

Of course, despite the continual debate between running experts, coaches, athletes and academics, there is still no unified theory of running technique. As technologists develop products like Sensoria and others, coaches will have to figure out how to use this new type of data. Helping runners become more efficient is the ultimate goal; reducing injury may be its most powerful application. “If you can get enough biomechanical data from a large enough sample of runner, you can hopefully have enough data to start to notice trends with injuries,” says Magness. The individualized, real-time monitoring will allow runners to precisely understand how to improve their gait, allowing for both changes on the fly and the application of specific drills in training to strengthen and remedy weak areas. Abshire believes that we will eventually find that over-striding—landing with the foot in front of the hips—causes many running injuries. If Abshire is correct, using a device to avoid an elongated stride could reduce injury.


These novel technologies are on the verge of crossing the gap from measuring the consequences of a runner’s effort to measuring causes. Running experts will have to figure out ways to take advantage of these new data, but they have the potential to revolutionize training. Watches to display the info are already on the market. For these advancements to change the sport, runners will have to forgo the sport’s minimalistic ethos and embrace more equipment.. “I think [runners] can benefit so much from open-mindedness and a few new tools to have fewer setbacks,” says Abshire. Soon, the tools to transform training for the better will be ready.

*A Brief History of Endurance Testing in Athletes, Stephen Seiler, Sportscience 15, 40-86, 2011. University of Agder, Norway.