March 24, 2017

It was no small task for our engineers to deliver the functionality of a wrist-based tracker in a small and comfortable form. We’ve had to find creative ways to track heart rate while also maintaining a long battery life. We also had to ideate a new experience to get you the perfect Motiv Ring fit, as fit is important for both comfort and performance. Take a look at some of the tech behind Motiv Ring’s tracking capabilities and tips for maximizing your Motiv experience.

Motiv Ring and heart rate

The optical heart rate sensor in Motiv Ring is an industry standard in the wearable market, but Motiv is the first company to put that sensor in a ring. This sensor utilizes a green LED – a color we chose to optimize the signal quality of that sensor – and travels to the capillary level of your finger. The powerful light-sensing photodiodes are located on either side of the LED and detect the amount of light reflected back to determine your pulse.

We optimized our system to sample heart rate when it matters most, in order to maximize battery life. When we sense step activity, the heart rate sensor activates. For all those times you’re not generating steps, we check your heart rate every few minutes and if we detect that your heart rate is elevated, we engage the sensor to track continuously those times you are active.

While Motiv Ring is great at tracking step-based activities, certain exercises don’t lend themselves to reliable heart rate readings. Here are some of the factors that can affect the accuracy of your heart rate data and the things you can do to get the best readings possible.

For best results, find the right size

One of the most important things you can do is ensure you have the right Motiv Ring size. With our Motiv Ring Sizing Set, you can take as much time as you need to try on different sizes before choosing your size. We recommend wearing the sizing rings for 24 hours to ensure you find the best fit.

With the right size, your Motiv Ring should be snug but comfortable, maintaining contact all around the inner part of the ring. A good test is to twist the ring a couple times around your finger. If the skin moves with the ring, you have the right fit. If not, try a smaller size. If you have two sizes that feel like a good fit, it’s best to choose the smaller size, as long as your ring is comfortable.

Finger selection matters

When choosing a ring size, finger selection is important. We tend to see the strongest signal strength from the index finger, but the middle, ring, and pinky fingers can also have strong signal strength. Some factors to consider when thinking about finger selection are:

The development of capillaries, which deliver blood, is influenced by use of the finger. Just like other areas of the body, the more the area is used the denser the capillaries. So, the more widely used fingers are likely to have greater blood flow, yielding stronger signal strength.

Bone structure, specifically knuckles, can impact performance. A snug fit must be accomplished while retaining the ability to remove and replace the ring. A finger with a knuckle much larger than the circumference of the finger should be avoided.

Factors that can impair signal quality

For certain exercises, such as Crossfit or weightlifting, it may be difficult to auto-detect Active Minutes. This is because when you’re lifting heavy weights for an extended period of time or gripping something tightly, it’s more difficult for the heart rate sensor to get a clear reading. This is consistent with all optical sensors, which is why wrist-based devices have the same problem.

The sensor can accommodate for movement related to locomotion, like arms pumping while running, but cannot adjust for movement of the tissue under the sensor, like flexing or moving the muscles of the fingers. This means that disturbances and pressure changes, such as dribbling a basketball, punching, or tightly gripping handlebars, could impact signal possibly beyond our ability to correct.

Another factor that can impair signal quality is temperature, as in cold weather blood can retreat from your fingers, which can also make it difficult for the heart rate sensor to get a clear reading.

Optimizations

If you find that you have trouble with getting a solid heart rate signal, here are some options that tend to increase available signal:

  • Maintain a fully closed but relaxed fist during walking and running events. This limits the additional, isolated movements of the finger, and a good fit allows a fully closed fist to occur without feeling uncomfortably constrictive.
  • Wear gloves during cold weather activities to enhance blood flow.
  • A warm-up may be needed to encourage blood flow.
  • Avoid gripping treadmill handlebars or side rails while walking or running as it can impact our ability to track steps (as your hands aren’t moving). Gripping strollers, push-carts, etc. can also limit signal.

Adding and editing

In the Motiv app you can manually add or edit activities that we may not have captured due to factors listed above. We help translate those activities into active minutes, and will calculate the number of calories you burned. We’ll also look at the time period for the activity you added, and input any step or heart rate data collected by the ring.

The Motiv advantage

These are all things we are working on and that we will continue to improve. We are constantly gathering data and testing rings to make sure you have the best experience possible with your Motiv Ring. We aim to focus on the moments that matter, but also track more of your day that others may be missing. Despite these challenges, Motiv Ring has advantages to wrist-based devices. Tattoos or even too much arm hair can affect the quality of your heart rate data when wearing a wristband. These factors are much less common on the finger, and the lighter part of your palm also helps with heart rate data collection. Our variety of sizes and sizing process also make it easy to find the right size, which is the most important thing you can do to get the best data. Above all, the comfort and wearability of such a slim device make it easy to keep on all the time.