Tuesday, June 23, 2015

Fitness Week #2: Targeting

Yesterday an article on fitness trackers popped up on my Facebook timeline, found here.  I thought it was an interesting article on people's interaction with wearable fitness technology, even if I disagree with some of the negative sentiments.  Specifically the following passage:

Perhaps more alarming, many felt under pressure to reach their daily targets (79%) and that their daily routines were controlled by Fitbit (59%). Add to this that almost 30% felt that Fitbit was an enemy and made them feel guilty, and suddenly this technology doesn’t seem so perfect.

My specific disagreement here is with the notion that feeling "under pressure" is a bad thing.  On the contrary, I like to feel that I'm setting goals that take me far out of the comfort zone, toward the realm of accomplishment.  But that's not the point of this blog.

Here's what is: How much am I ruled by the targets in my fitness tracker?


So how might targets effect my behavior using a fitness tracker?  In two general ways that I can think of:
  • Psychological targets: I set internal goals, just wanting to hit 20,000; 30,000;40,000 for today, etc.
  • Vivo Fit Targets: My Garmin Vivo fit sets a dynamic target for me each day, that grows as I become more active.  It started at a low default (6,500) but has grown to about 16,500, which is where it has been for about the last month.

You can read about my prior models of my fitness data here and at other prior posts, but if I want to measure the impact of targets, I may want to control for some meta factors, specifically day of the week.  This graph gives a reasonable view of day of week variation.

So this proves that weekends are significantly different than weekdays, to a tune of 6-8,000 steps.

Side note:   My Thursdays especially suck, which isn't particularly surprising.  On Thursdays I'm generally exhausted from the week, and I have a day packed full of sit-in-place meetings at work.

What does this mean?  Let me develop a hypothesis:  Because I'm closer to the Vivo Fit goals on the weekdays (due to less time, more office time, etc), I'm likely more driven to hit those numbers, whereas on the weekends when I have more slack (and know I'll easily hit the Vivo Fit goals) I'm morelikely driven to psychological thresholds.  Let's see what the numbers show...


I hypothesized that during the week, my behavior would track to the Vivo Fit targets, and thus my numbers would hover around those targets.  How do I prove that though?  

See graph below.  Over the most recent time period, my target has been between 16,000 and 18,000, where as prior my goal was much lower.  The chart below shows an obvious impact, as my target shifted, my behavior shifted.  Though I'm not walking a ton more steps on each day (17440 versus 18450; t-test p value = .26), I'm far less likely 10% versus 25% to have a "low step day."


My hypothesis states that for weekends I would see bumps at psychological thresholds, and this is fairly easy to see in the data.  Two major points stick out:

  • 20,000: A huge bump here, indicates me just trying to get to the 20K mark on a weekend day.
  • 40,000: I've never had between 34000 and 40000 steps, however I have two days at 40K.  To be honest, the data is much more obvious here, because two days are 40,091 and 40,125.  Each barely over the mark, indicating me trying to hit a target (I remember walking in circles to hit one; please don't judge).


I had a strong reason to believe that since getting my Vivo Fit 2, my life had been largely about targeting specific numbers.  I now have fairly strong evidence to prove this.  Will this change my behavior?  Probably not, but hey, at least I've quantified my quantification of fitness.

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