Using Data to Run a Faster Marathon

This is Steve. Steve entered a marathon, aiming to run it in sub 3 hours but ended up with a time of 3:06:36.

But did Steve go out too hard?

After running the first half of his marathon in 1:29:04, Steve followed up with a second half of 1:37:22, a decrease in average pace from 4:12 min/km to 4:36 min/km. These two simple data points suggest that Steve went out too fast for his fitness level and sub 3hrs was never on the cards. Case closed. But, if we look more closely at the data, a more complicated picture emerges…

Steve’s average heart rate was 160 bpm at 92.5% of his lactate threshold (LTH) for the first half of the marathon. That’s well within zone 3 and below his previous 3-hour peak HR of 163 bpm = 93% LTH. Similarly, Steve’s average pace (4:12 min/km) represented 95% of his lactate threshold, a value at the upper end of marathon prescription, but not likely to be responsible for the 8% reduction in speed over the second half of the race.

TrainingPeaks marathon running data
Steve's Marathon data with the first half highlighted

Luckily, Steve was running with a Stryd Running Power Meter, allowing a more thorough analysis of his performance. So, let’s have a look. Steve’s average power for the first half of the race (366 W) corresponded to 92% of his lactate threshold (intensity factor, IF, in TrainingPeaks). Well, that doesn’t add much to the story, as it supports the fact that Steve was running within zone 3, which is below his anaerobic threshold and aligns with the physiological capabilities of a 3 h marathon runner.

Why not throw some 5km efforts into your marathon!

To gain more information, we can look at Steve’s peak outputs for the race.

His peak pace for 1 km was 4:00 min/km or 98% of his lactate threshold and this occurred in the first 10 min of the race. While that’s slightly too fast, it’s not outrageous, and I can see it was on an -0.5% gradient and his power was still in zone 3, just.