Life happens. I get it.
When targeting certain aspects of our health and fitness, significant life events are just another set of variables to contribute to or take away from our goals. Determining the extent to which each life event (e.g., marriage, graduation, a new job) affects our well-being can be left to guesswork, or we can take a scientific approach to understanding these variables.
Two Targets Over Time
Juan and I targeted two important indicators for his overall fitness.
First, we measured the total exercise minutes per week. With the recommendation of meeting a minimum of 150 minutes per week, Juan easily met this goal within the first few months of working together.
(The blue line indicates 150 minutes per week)
Second, we monitored the resting heart rate (RHR). Resting heart rate functions as a lagging indicator describing Juan’s overall fitness. As lower rates are associated with beneficial long-term health outcomes, I collect these data for all of my clients.
Plotting RHR, the results are fantastic to date. From 65 beats per minute to below 60 today:
Given the body of our work together, at this time of this blog, Juan and I accumulated nearly 2 years’ worth of data. The graphs referenced here amount to almost 100 data points for both exercise minutes and RHR!
The Trends of Each
Putting these charts side-by-side they look like to rollercoasters. Both are going up and down:
However, when plotted together, we notice changes in both tend to correlate (inversely) together. That is, when exercise minutes go up, RHR goes down. And when exercise minutes go down, RHR goes up.
What gives?
This is where a scientific approach to documenting and identifying significant life events helps explain the roller coaster ride we see with exercise minutes and RHR.
Exercise, RHR, and Reversal Designs.
Life throws us curveballs and allows us to evaluate natural experiments throughout our lives. For Juan, he experienced the following:
- In December 2021, we established his training program
- In October 2022, he prepared for a new job and relocation to a new state
- In January 2023, he moved to a new state and started a new job
- In March 2023, his lifestyle stabilized
- In April 2023, he targeted increased cardio minutes (biking, walking)
Taking that same chart above, we can throw phase change lines (vertical lines) on the graph to indicate when the life event and exercise program changes occurred and its detail:
Given how both variables – exercise minutes and RHR – changed systematically overtime when these phases occurred, we can infer causality between the two:
When exercise minutes tended to INCREASE, resting heart rate tended to DECREASE. Because we see this relationship repeat itself multiple times, my confidence in causality increases and increases.
When exercise minutes increase, RHR improves.
The natural reversal design
Reversal designs are common in behavioral science and allow you to reverse conditions to determine causality. In the lab, variables are easy to change. In real life, not so much.
We look at these reversals in phases when a set of conditions is relatively stable. In essence, we navigated an A-B-C-D-B reversal design.
- Phase A – baseline, no exercise routine
- Phase B – consistent exercise routine
- Phase C – life event 1
- Phase D – life event 2
Today, we are in the second B-phase of Juans training and lifestyle changes. We have navigated back to similar weekly exercise minutes as the previous B-phase and a lower RHR!
This summer, we will target new exercise movements and build off an even more impressive baseline.
I can’t wait to see what Juan does next!
