Over the past several years, as the popularity of Ironman racing has increased, so too has the availability of devices for tracking our training and racing metrics. As race day in Kona nears, what are the most useful tools for tracking how we’re doing and what to expect on race day? Having coached dozens of athletes across the Big Island’s finish line, I have learned that the following 10 metrics can make or break you on race day, regardless of your fitness.

Six weeks out

You should track these first two metrics as early as six weeks out from race day. This allows enough time for adjustment if they are not changing as expected.

Workout performance

The first thing that I like to track is something that can be used throughout the year, but becomes most important during the final six weeks before race day. Generally, each heartbeat is worth about three seconds per mile while running and approximately three watts on the bike. Within about a 10-beat span, you can use this rule of thumb as a calibration to judge your current fitness. For example, if you do one run at 7:45 pace with a heart rate of 140 bpm, and the next run at 7:30 pace with a heart rate of 142 bpm, you can adjust the second run by two beats, the equivalent of six seconds per mile, to compare the two runs. In this example, the second run would have been at 7:36 pace if you had run it at a heart rate of 140 bpm, and therefore it indicates an improvement of about nine seconds per mile. Of course heat, duration and terrain can have a significant impact, so always try to use similar weather and terrain when making this type of comparison. What you should find is that your fastest workouts are during the taper and race week. If not, maybe it’s time to consider more rest! Also, check out my free tool at Triathloncalculator.com to better define your expectations and race-day pacing.

Body fat

This is typically a much better metric to track than body weight, as it mostly factors out fluctuations in fluid retention related to sodium and fluid intake. Body fat tracking is usually best done using skin-fold calipers, which tend to be significantly more accurate than digital scales. You can find calipers for less than $20, and they are very easy to use. Appropriate body fat goals are best determined with the help of a registered dietitian or a coach. If you could stand to lose a few pounds, keep in mind that a single pound is typically worth about three seconds per mile when running, one minute over the course of a 70.3 and two minutes in an Ironman. But leaner isn’t always better. The objective is to hit your race weight during race week, not sooner. You certainly don’t want to overdo it!

For more tips on ensuring you reach your peak fitness for Kona, see Part II of Big Island Metrics two weeks out from race day. This original article by Jesse Kropelnicki appeared in the October/November 2012 issue of LAVA Magazine. To subscribe to LAVA Magazine, click here.