Race Shape › Answers

Endurance training questions, answered

Short, sourced answers to the questions runners, cyclists, swimmers and triathletes ask most. Each one opens with the answer, shows the numbers the Race Shape engine actually uses, names its sources, and says plainly where the evidence is thin — the 10% rule, for example, is a sensible convention rather than a proven threshold.

Questions about injuries, energy availability and clinical nutrition are deliberately not here. Those need a qualified professional, and we would rather send you to one than guess.

Running

• What is VDOT?
  VDOT is Jack Daniels' single number for running fitness. What it is, how it is worked out, a table from 5 km times, and where it breaks down.
• How fast should easy runs be?
  Easy runs should be slower than most runners run them. The easy pace ceiling by 5 km time, why it matters, and how to use heart rate instead.
• What is threshold pace?
  Threshold pace is the pace you could hold for about an hour. What it is, a table by 5 km time, and how threshold sessions should be run.
• How long should a long run be?
  How long a long run should be: the caps by race distance, why the long run should be a share of the week, and why marathoners rarely need to run 42 km in training.
• How many days a week should I run?
  How many days a week to run: three to six depending on your goal. What the week looks like at each, and why consistency beats a sixth day.
• How does altitude affect running pace?
  Altitude slows running pace for the same effort. The correction Race Shape applies in South African towns, and why to correct only for the difference.

How long it takes

• How long does it take to train for a half marathon?
  How long it takes to train for a half marathon: 12 weeks for most runners, 16 for a first, what to build, and the paces that matter.
• How long does it take to train for a marathon?
  How long it takes to train for a marathon: 16–20 weeks for most runners, what the weeks are for, and what a short block can and cannot do.
• How long does it take to train for Comrades?
  How long it takes to train for Comrades: about 24 weeks on a marathon base, what the build needs, and why the long run is capped.
• Can you train for a marathon in 8 weeks?
  Can you train for a marathon in 8 weeks? What a short block can and cannot do, and how to run the race if you go ahead.

Cycling and swimming

• What is FTP, and how do I test it?
  FTP is the power a cyclist can hold for about an hour. What it is, three ways to test it, zones for a 250 W FTP, and why to test where you ride.
• What are cycling power zones?
  Cycling power zones as percentages of FTP, using Coggan's model: what each zone is for, and the watts at three fitness levels.
• How do I train by heart rate without a power meter?
  Training by heart rate without a power meter: how to find threshold heart rate, zones for running and cycling, and how reliable age-based estimates are.
• What is Critical Swim Speed?
  Critical Swim Speed is the swimming equivalent of threshold. How to calculate it from a 400 m and 200 m, and the training paces it sets.

Triathlon

• What is a brick workout?
  A brick workout is a bike ride followed straight away by a run. What it trains, how bricks fit into a triathlon plan, and how long the run should be.
• How should I pace a 70.3 half Ironman?
  How to pace a 70.3: about 75% of FTP on the bike, a run about 11% slower than a fresh half, and why the bike is where the race is lost.
• What is Training Stress Score?
  Training Stress Score combines duration and intensity into one load number. How it is calculated, why intensity is squared, and why it matters for triathletes.

Structuring training

• What is the 80/20 rule in endurance training?
  The 80/20 rule: roughly 80% of endurance training at low intensity. Where it comes from, why counting by minute matters, and why amateurs drift from it.
• How much should weekly training increase?
  How much weekly training should increase: the 10% rule, what it looks like week by week, and what the evidence actually says about it.
• Why is every fourth week easier in a training plan?
  Why every fourth week in a training plan is lighter: how recovery weeks work, what they contain, and when a different ratio suits better.
• What is a taper, and how long should it be?
  A taper is the drop in training volume before a race. How long it should be by distance, what changes and what does not, and the evidence behind it.
• What are A, B and C races?
  A, B and C races set how much each race matters. How a plan tapers for each, and why treating most races as B or C builds a better season.

What the evidence says

• Does strength training make endurance athletes faster?
  Does strength training make you faster? Not by raising VO₂max, but by improving running economy and reducing injuries. The evidence and the dose.
• Does stretching prevent running injuries?
  Does stretching prevent running injuries? A meta-analysis of randomised trials says no, while strength training does. What to do instead.