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Why Starting Too Fast on Hills Can Ruin Your parkrun | Dunedin Analysis

qwikkiwi January 20, 2026 No Comments

parkrun Progress Report (Part 1): Jess Bray at Dunedin parkrun (05-Apr-25)

Dunedin parkrun is one of those courses where pacing can make or break your result.

It starts fast and runnable, but once you reach the middle kilometres the terrain demands respect. If you go out hard early to “bank time”, the hills can take it all back — and then some.

In Part 1 of this two-part parkrun Progress Report series, we’re analysing Jess Bray’s run from 05-Apr-25, where she recorded 22:36, and the data gives us a very clear lesson in effort distribution on a hilly course.

Jess’ Splits

Jess’ kilometre splits were:

  • Km 1: 4:01
  • Km 2: 4:05
  • Km 3: 5:05
  • Km 4: 4:57
  • Km 5: 4:33

At first glance, what stands out is the pattern:

✅ Fast opening 2km
⬇️ Significant slowdown in 3rd and 4th km
✅ Partial recovery in the final kilometre

That pacing profile is extremely common on courses that go from flat to rolling or hilly — especially when the first kilometre is run at close to PB pace.

Course Profile: Flat First, Then the Work Begins

Here’s what the terrain looked like across the run:

  • 1–2 Km: Flat
  • 3rd Km: +45m gain / -21m loss
  • 4th Km: +37m gain / -41m loss
  • 5th Km: +15m gain / -32m loss

The key detail is that the challenging work happens in the middle kilometres. Third and fourth Kilometres include the biggest climbs and the most variation, and that’s where the pace drifted.

Even though there’s some downhill mixed in, the net cost of the climbs still shows clearly in the splits.

Pacing Interpretation: “PB Pace Early… Paid for It on the Hills”

The story of this run is simple:

Jess ran the opening two kilometres hard on the flat — 4:01 and 4:05 — then hit the climbing section and couldn’t sustain the same speed once the terrain turned.

This isn’t a blow-up. It’s a smooth, predictable pacing penalty that often happens when athletes start just a touch too aggressively before hills arrive.

If you race the flat section like it’s a flat course, you’re usually forced into damage control once you reach the climbs.

Normalised Power: Strong Effort Through the Tough Section

Here’s Jess’ Normalised Power for each kilometre:

  • 1st Km: 275W
  • 2nd Km: 267W
  • 3rd Km: 273W
  • 4th Km: 267W
  • 5th Km: 240W

This is one of the most telling parts of the analysis.

From kilometres 1 to 4, Jess’ power stays remarkably consistent — roughly in the 267–275W range. That tells us:

✅ She didn’t give up when the hills arrived
✅ She kept working hard through the hardest part of the course
✅ The slower splits were driven by terrain and fatigue, not a loss of intent

But then we see the drop in the 5th kilometre to 240W.

Even though the pace improves to 4:33, the power drops significantly — a classic sign that the speed is being assisted by the terrain (more favourable gradients), while the athlete is no longer able to produce the same output as earlier.

Heart Rate Trends: Early Intensity, Then Managing the Cost

Jess’ average and max heart rate by kilometre:

  • 1st Km: 166 / 182
  • 2nd Km: 186 / 191
  • 3rd Km: 172 / 190
  • 4th Km: 172 / 180
  • 5th Km: 174 / 182

The standout number here is the second kilometre: 186 average HR.

That is extremely high for an “average” value, and while there’s always a chance of sensor issues, it aligns with the pacing story:

  • A strong start
  • A hard push through the flat section
  • A big cost once climbing arrives

In other words: even if Jess felt comfortable at 4:01–4:05 pace early, her physiology may have already been near the limit.

The Key Lesson: Dunedin parkrun Rewards Restraint

This run is a perfect reminder of something every hilly-course parkrunner needs to learn:

You cannot “bank time” early on a course that gets harder later.

The time you gain in the first two kilometres is often less than the time you lose when you hit the climbs with fatigue already building.

The smarter approach for this course is typically:

  • Slightly calmer opening 2km (often 5–10 seconds slower per km)
  • Maintain rhythm and power through the climbing section
  • Save enough to push the final kilometre with intent

This doesn’t require more fitness. It requires better distribution of effort.

Why This Matters for Part 2

This is Part 1 of a two-part Dunedin parkrun series.

The reason it’s so valuable is that Jess is capable of a faster run here — and when we compare this performance to her course PB, we’ll be able to highlight exactly what changed:

  • pacing decisions
  • power distribution
  • effort timing
  • and how to handle the hills more efficiently

That’s where the big learning (and the time gains) will come from.

Want Help Improving Your Own parkrun?

If you want to run smarter, pace better, and finish stronger every Saturday, I can help.

🚀 Join parkrun Kickstart

A 4-week plan designed to build pacing confidence, consistency, and stronger 5km execution.
👉 https://www.coachraytraining.co.nz/signup/parkrun-kickstart

🟢 Apply for Your Own parkrun Progress Report

Get a personalised performance breakdown just like Jess’ report here.
👉 https://qwik-kiwi.kit.com/parkrun_progress_report

Ka kite anō — and all the best for your next parkrun.

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