cadence

Gear Test

/ Stuart / Leave a comment

GarminForerunner225This week we look at Garmin’s Forerunner® 225. This is Garmin’s first GPS running watch with wrist-based heart rate monitor (HRM). In the box it bears the striking family resemblance of most of the Forerunner® models—clear display, four good-sized buttons around the bezel, chunky strap and subdued colour scheme.

It’s out of the box where the difference becomes more obvious. It’s lighter than my old 110 for a start—disconcertingly lighter at first, there is also a rocker button rather than a straight push button on the lower left of the bezel which hints at more interactivity. Turn it over and the biggest difference is now clear.

A raised silicone rubber ring holds the back of the watch slightly proud of the wrist and seals the back from light ingress for there at the centre is the clever bit. Utilising ‘Mio Heart Rate Technology’ the watch shines light deep in to my wrist to seek out my pulse from which it will calculate (via a sophisticated filtering process) my heart rate. Excitedly, I entered my user data into the watch on the train home from the shops—guesstimating a couple of fields and settling for the ready-to-run maximum HR of 220 minus age.

225_HRPaceandCadenceI took the watch out for its first spin the week before last. It was an interval session in the local park (the first one in a while)—a fifteen minute warm-up in which my HR seemed to go rather high (into the orange Threshold zone) even at a very gentle jog, then it was three sets of 3 minutes hard with 2 minutes recovery. During the final interval it quickly became clear that the standard formula for HR wasn’t working for me as I peaked at 186bpm during a final ‘sprint’ as can be seen on the Garmin Connect data graph above.

I’ve excluded the elevation in the overlay as the run was pretty much flat but the grey of my pace shows the lopsided warm-up (5.5 min/km) and warm-down (6.75 min/km) with the three peaks of the intervals (4.3 min/km) and their two rests sandwiched in between. The cadence facility was a new one on me but it seems about 180spm is optimum—I was hitting this on the intervals but not on the ‘easy’ sections when I was down at about 160spm. Apparently my average stride length was 1.15m. Oh, and I burned 568 calories (that’s about six bananas).

BlapBack from my run and I was looking forward to taking the 225 out for a more hilly adventure…and then BLAP! I’ve been hit by a virus and running is off the menu for a little while. The time off has though given me a chance to re-set my maximum and resting HRs and to realise that I had underestimated my height and over estimated my weight. Not by much but enough that I should imagine the cadence results are skewed and a 20 beats rise in my maximum HR will have had an impact on the training zones which are based on percentages of HR between resting pulse and maximum HR. It’s also highly likely that the virus was the culprit for the high HR during the ‘easy’ sections.

What do all these data do though? There is some form of reification of flows happening here…the peaks, troughs and flow of the data graphs are hardenings of my activity out in the park. The data have been pasted onto a linear chronometric from which I can quickly spot patterns of performance. Unsurprising co-incidences appear as cadence, HR and pace seem to track each other and once I add in the ups and downs of a hilly run more profiles will interweave.

The side-on exaggerations of the elevation profile will dictate at least one of the other flows—my pace drops, my stride-length shortens, my HR increases—and all will be presented to me in graph form once I sync the watch to the computer. The “transitory hardenings in the flows” as visualised by the graphs will dictate future runs, how I approach terrain.1 Some runners run to HR…should I try that and see where it gets me? After all I had invested in the 225 to try to provide a little more accuracy into my training. (Once formed, these hardenings, “react back on the flows to constrain them in a variety of ways”.2) Whilst I don’t agree that there are wasted kms in terms of running, in terms of training to race what I was doing was wasted—a bit half-hearted—too fast for easy/recovery but too slow for meaningful speed work.

Now, if I can just shake off this virus thing I can start playing with the profiles of the peaks and flows of running data.

[1] Manuel De Landa, A Thousand Years of Nonlinear History (New York: Swerve, 1997)258-9.
[2] ibid.