Personal Activity Intelligence (PAI), the Next Big Thing in Wearable Technology: a Review

When I say, PIE, what comes to mind?  Apple, cherry, strawberry, banana cream or pumpkin of course.

Figure 1.  Google Image Search of Pie.

Figure 1. Google Image Search of Pie.

But that’s not what I’m referring to here.  What I’m talking about has the potential to be the next big thing in wearable fitness technology, Personal Activity Intelligence or PAI (pie).  Sounds cool and catchy, right?  We have smart phones, smart cars, smart thermostats, finally, we have “smart” exercise. 

PAI is the product of a collaboration between a company called MIO GLOBAL and a Norwegian Sports Scientist, Ulrik Wisløff.  I first encountered PAI and Dr. Wisløff at the American College of Sports Medicine National conference in Denver, Colorado in June of 2017.  To say that I was excited about PAI after this conference was an understatement.



The reason why PAI is such a breakthrough is that it solves the following problem: not all steps (movement) are created equal.  Walking, running, taking the stairs, strolling through the park, window shopping, and climbing a mountain are performed at far different intensities and have drastically different effects on energy cost, fitness levels, and health, yet the majority of wearable devices treat all steps as being the same (see their video below).

Although many of today’s fitness trackers can measure heart rate, most people have no idea how to use this information (other than bragging about resting heart rate).  This is where PAI comes in.  PAI awards you “PAI points” for moderate to vigorous activity as indicated by your heart rate data.  The more vigorously you exercise, the more PAI points you accumulate.  PAI then tallies your points over a 7-day rolling average.  If you have 100 or more points over a week, you’re good to go, less than 100, you better get some more exercise.

Figure 3.  Seven Day Rolling PAI Average.

Figure 3. Seven Day Rolling PAI Average.

Figure 4.  One Day of PAI; Hour by Hour.

Figure 4. One Day of PAI; Hour by Hour.


Not only is PAI easy to understand, it also simplifies exercise prescription.  When you think about it, how is exercise prescribed and tracked?  Our current recommendations are diverse and are prescribed under the following variations:

  1. Thirty minutes of moderate to vigorous aerobic activity on all or most (5+) days of the week and
  2. Resistance exercise 2-3x/week or
  3. Obtain 10,000 steps/day or
  4. Track your distance in miles

Here are the problems with each of these measures that PAI solves.

1) I’ve never spoken with anyone who diligently tracks exercise time.  You might say, let’s go for a walk but do you actually track the total time you walk and add it up over the course of a week?

2) Accelerometers (i.e. Fitbit) do a terrible job of tracking resistance exercise.  I’ve known (and personally experienced) a great number of people lifting very heavy weights (think CrossFit) and yet after a workout that nearly kills them, they obtained a measly 800 steps.  Are you kidding me!  I almost died during that workout.  Squatting down to sit on the toilet hurts and yet, you’re only giving me 800 steps?  [Insert your expletive of choice here]!

3) People can obtain 10,000 steps per day without an elevated heart rate.  For example, as part of their jobs (i.e. a department store worker) many people will be active for a large majority of his/her workday (6+ hours) but will be operating at an extremely low intensity because they are not a) continuously moving fast enough or b) repetitively lifting something heavy.  Although they have spent a great deal of time being active, they were not moderately to vigorously active to the point where they will become more aerobically fit.

4) One can also track distance covered (in miles) but this seems to be more common in runners and cyclists rather than the general public.

PAI solves each of these problems by being able to distill down time, exercise intensity, steps/day, and heart rate into one meaningful, understandable metric, PAI!

In my mind, PAI could be the new exercise currency.  Not time, not reps, not steps, not distance, PAI.  Instead of 10,000 steps/day or 150+ minutes of exercise per week, get 100 PAI each week.  If you can get 100 PAI over a 7-day rolling average, you’re right on track!  And there is sound scientific evidence to back PAI up.  PAI also puts into action what we've known for some time, that when it comes to health and longevity, fitness is more important than physical activity (Figure 5).

Figure 5.  Effects of Physical Activity versus Physical Fitness and Relative Risk of Mortality  (Williams, PT 2001 MSSE).   Fitness (PAI) is a much better health predictor than physical activity (total steps).

Figure 5. Effects of Physical Activity versus Physical Fitness and Relative Risk of Mortality (Williams, PT 2001 MSSE).  Fitness (PAI) is a much better health predictor than physical activity (total steps).

My Review of PAI:

Now with all the potential that PAI has, I must say that I have been extremely disappointed and frustrated with this device (MIO GLOBAL SLICE) for the following reasons:

1) PAI seems to be WAY too dependent on vigorous exercise.  For example, I rode my bicycle 18 miles (to and from a brewery) and yet I received “0” PAI!  An 18-mile bike ride should warrant some PAI.  I understand the connection between moderate to vigorous exercise and fitness (Figures 5 & 6) but anyone who knows me, knows that I don’t “lolly gag” on a bike!  I’m in decent shape but not the kind of shape where I can ride 18 miles without elevating my heart rate.  

2) De-valuing movement.  Tying into point #1, low intensity and moderate intensity exercise gets treated like (insert derogatory metaphor here) by PAI.  Exercise physiologists and public health professionals might as well have a giant Metabolic Equivalency Table (MET) bonfire.  Gardening, yard work, washing dishes, doing laundry, vacuuming, and walking for your health…apparently, none of this “low” intensity physical activity matters anymore.  Figure 4 shows that I was "low intensity" active for 1 hour and 29 minutes on July 24th and yet received no PAI. 

According to this system we should just do 14 minutes of high intensity exercise/day and call it quits (I might actually try this).  In a society where public health professionals are fighting our “sedentary” epidemic, I don’t think it is a good idea to encourage people to adopt an “all or nothing” approach to getting physical activity.  Presumably I could bike 100 miles at a low intensity but wouldn’t get any PAI.  This doesn’t make sense.

Figure 6.  PAI Zones for a 35 Year Old

Figure 6. PAI Zones for a 35 Year Old

3) Mystery PAI.  I have accumulated 40 PAI overnight when not even wearing my device.  This is just plain stupid.  I don’t know how else to address this flaw.

4) Low battery life.  MIO GLOBAL claims that you can go 5 days without a charge.  That doesn’t seem possible as more often than not, wearing the MIO GLOBAL for one day results in a battery at less than 50%, so I charge it overnight to ensure that I can use it the next day.  That’s fine.  I charge my I-Phone every night but when you’re used to a Fitbit Zip that requires a battery change once every 3 months, this is a big ask.

5) I don’t trust the heart rate feedback.  Maybe I should have listed this deficiency first or maybe I am saving one of the best for last.  But there have been numerous times where I am working exceptionally hard (uphill, near maximal effort on bike) and my heart rate is 126?  Give me a break.  In addition to the heart rate being inaccurate/untimely, oftentimes I will perform a workout at a given time, let’s say 3pm and my PAI points in the application will show up at 6pm.  It would be useful if PAI was better synced with the time I am performing my exercises so that I am more aware of the types of exercise that award me more points.

6) Your PAI data is deleted after 7 days. While writing this post I decided to look back at my PAI data and compare it to my Fitbit Zip.  Much to my chagrin, PAI data is erased from its application after 7 days.  Grrr.

7) Other observations.  The MIO GLOBAL SLICE is priced comparably to other wrist worn activity trackers.  I haven’t worn a Fitbit or Garmin activity tracker but they can’t be as uncomfortable as the SLICE.  Please take a note out of Timex’s book: they make an ultra- comfortable wrist watch for $30.  I know these devices are completely different but please make it happen.  I know, I know that means millions of (re)design hours and distribution complexities that I don’t even begin to understand, but…..please. 


Final Conclusions:

1) Don’t buy a MIO GLOBAL SLICE (PAI) in its current version!  It’s not worth it!

2) PAI is a super cool concept that could be the future of the accelerometer world.  For the fitness world, PAI could become as commonplace in our vernacular as the previous non-existent terms/things such as the I-POD, I-PHONE, Facebook, Twitter, etc.  It has the potential to be a game changer.  It’s just not there yet.

3) It is important to note that PAI is a fitness tracker, not an activity tracker.  If your goal is simply to move more, a Fitbit Zip will do the trick.  Although I didn't show you the data, the SLICE was horrendous at counting steps, not even close to the Fitbit Zip I was simultaneously wearing. 

4) Wearing the MIO GLOBAL SLICE has been interesting.  I want this to work more than anything.  I was so excited about this.  I even had a client of mine buy one of these.  For his sake and mine I regret buying this.  It just isn’t ready yet.  The theory is great.  The execution is terrible.  Maybe I should have listened to the online reviews.

Figure 7.  PAI Reviews on Google Play.  Maybe I should have listened.

Figure 7. PAI Reviews on Google Play.  Maybe I should have listened.


Todd M. Weber PhD, MS, RD