Are Mio products accurate for activities like weight lifting, crossfit, and high intensity interval training?

It depends! Mio products work by using an optical sensor to monitor the volume of blood in your veins. Your blood volume changes as your heart beats, and sophisticated algorithms are applied to determine which part of that change is due to your heart pumping blood, and which part is due to arm movement. Mio algorithms have been refined over the course of several years, and if you're running, cycling, or doing some other type of rhythmic activity, your Mio device quickly recognizes the activity and is able to provide an EKG-accurate heart rate signal.
If you're performing an activity that involves more erratic arm motions (such as playing tennis, boxing, or doing intervals of plyometrics), your heart rate signal is more difficult to filter. Often in these types of workouts you're more interested in monitoring your heart rate during the recovery period between sets anyway, and if that's the case your Mio device will be great! But, if you need to look at your wrist and see your exact heart rate right in the middle of a set/round/interval, optical heart rate monitoring may not be the best technology match for you. Many Mio customers have fantastic results during these kinds of activities, but we can't guarantee that heart rate monitoring will be as accurate as it is with running or cycling.
To make sure you're getting the best possible results, try these tips:
  • Move your Mio device further up your arm so that it doesn't get in the way of wrist movements
  • Make sure your device has a snug fit around your arm. It doesn't need to be extremely tight; just make sure it doesn't move around
  • Try wearing your Mio device with the sensor on the underside of your forearm, instead of the outside of your wrist