Last month I competed in my third Tar Heel 4 Miler, the biggest race each year in Chapel Hill, North Carolina, where I live. They offer a 10 mile version too but I lose interest once I hit double digit mileage so the 4 Miler has become one of my key races each year since we moved here.
Last year I placed second in my age group so this year I was gunning for the win. They changed the race course this year so I didn’t have a baseline to work from. Instead, I ran the course a few days ahead of time and built a race strategy from there.
I only had one road race under my belt with Stryd so far, an 8k (5 mile) race last Thanksgiving. My average power in that race was 363W. Given that this race would be shorter and I had been training by power during the intervening months, I figured I could run at substantially higher power in this race. But how high? I simply didn’t know so I decided to run a progressive race, starting off around 360W (excepting the first km because I always go out hard) and then increasing 10W each KM if I felt good. I would be looking for ~4:20 KM splits but that was really an afterthought; I would be racing by power, not pace.
This is a “flat” race by North Carolina standards but still very hilly by mine. Although I have very strong legs, smaller/lighter runners usually have an advantage over me going up hills. All my fast twitch fibers help me cruise past them as I stride it out on the downhills, so my goal was to “hang on” during the uphill segments in the middle of the race and attack the downhills. The race ends on a big uphill where I usually do pretty well by virtue of not needing to leave anything in the tank afterward.
Such a short race is very anaerobic so I tried to fuel up in the preceding days to fill up my glycogen stores. This included my traditional chocolate cake the night before the race. Science tells us that, by then, the window for fueling is already past – but I conveniently ignore science when it comes to justifying chocolate cake!
The morning of the race I jogged from my house to the starting line as a warmup. It’s pretty much all uphill so I took it easy but still had a healthy sweat going by the time I arrived. I found lots of people I knew at the starting line (including my “nemesis” who is always very close to me in these races), which kept the atmosphere nice and relaxed. After a beautiful rendition of the National Anthem the starting gun sounded and we were off!
KM 1: Again, I always go out hot A. to avoid getting stuck in a pack and B. because I can’t NOT do it! The first KM was largely uphill so my goal was to rein it in at 370W. Long story short: I failed to hold back and the first KM averaged 414W. On the plus side, I had good positioning on the road so wasn’t hemmed in by other runners. My first KM split turned out to be exactly 4:20 and my heart rate reached 171 BPM, which was fine; I expected to run most of the race in the 170s.
KM 2: This was much flatter, even slightly downhill. My goal for this KM was to settle in at 360W and I almost achieved it, averaging 371W. This split was 4:09 and I was clearly cruising along as my average heart rate dropped to 168 BPM.
KM 3: I was feeling good so I elected to try to hold steady at ~370W. This had a long uphill segment, though, and my performance turned out to be identical to the first KM: 414W, 4:20. Heart rate averaged up to 175 BPM.
KM 4: Here we had another flatter, slightly downhill segment. I was feeling good, though, so I aimed to up the ante to 380W. I wound up averaging 385W and finished in 4:15. My heart rate average dropped to 174 BPM.
KM 5: Still feeling good; let’s take it up to 390W! This was a net neutral segment with both uphill and downhill portions. I averaged 399W and slowed significantly to 4:34 – but I passed my nemesis. HR still 175 BPM, which was fine.
KM 6: Less than a mile to go so time to stop thinking about holding onto any reserves; let’s keep it up at 400W! There were some significant downhills in this segment so I made my move and passed several of the runners who had been pretty close to me for most of the race. I averaged 392W but Stryd underreports downhill running power so I think I was actually pretty close to the mark. 4:15 split, 177 BPM.
Final 400M: This was just an uphill gutcheck: target 450W. A young marine who had been running with two other members of his battalion passed me on the hill and made it look easy; he must have been holding back to run with his buddies for the rest of the race. I still had a strong finish: 505W, 1:41 split. Heart rate hit 187 BPM, which is just a few BPM shy of my maximum.
Final time: 27:34 and I won my age group! 403W average power, much higher than I anticipated! Running by power really does take so much of the guesswork out of pacing when you’re on a course of varying elevation. The main question in my mind is: would I have run faster overall if I had run a more even power race – especially during those 1st and 3rd KMs? Now I have a pretty good average power target to shoot for during my next 4-mile road race (July) so I can aim for more consistency.
If you’re interested in my actual power data, here you can see how it is much better than heart rate for instantaneously monitoring intensity: