You've done the work. Months of training, early mornings, tempo runs in the rain. Now the race is 2-3 weeks away, and you face the hardest part of the entire training cycle: doing less.
Tapering — the planned reduction of training before a race — is where good training becomes great racing. Or where panic, impatience, and "one more hard workout" turn months of preparation into a mediocre result.
Here's how to taper by the numbers.
What tapering actually does
A taper doesn't build fitness. Your CTL (chronic training load) will actually decline slightly during the taper — and that's fine. What the taper does is reduce fatigue while preserving fitness, pushing your TSB (training stress balance) into the positive range where performance peaks.
The physiology:
- Muscle glycogen stores fully replenish (requires 5-7 days of reduced training)
- Muscle damage from training heals (microtrauma in muscle fibers needs time)
- Blood volume and red blood cell count stabilize at their training-elevated levels
- Neuromuscular systems sharpen — reaction time and coordination improve
- Mental freshness returns — motivation peaks when fatigue drops
Studies consistently show that a proper taper improves race performance by 2-6%. For a 3:30 marathoner, that's 4-12 minutes. For a 45-minute 10K runner, that's 1-3 minutes. These are massive gains from simply training less.
The science of taper design
Research on tapering (largely from Dr. Iñigo Mujika) has identified the key variables:
Duration
Optimal taper length: 2-3 weeks for marathons, 10-14 days for half marathons and shorter races.
Shorter tapers don't allow full recovery. Longer tapers risk fitness loss. The sweet spot depends on how much fatigue you've accumulated — which is where training load data becomes invaluable.
Volume reduction
Reduce weekly mileage by 40-60% over the taper period.
This is the primary lever. Most of the taper's benefit comes from running less. The reduction should be progressive — not a sudden drop.
Example for a marathon (3-week taper):
- Taper week 1: Reduce volume by 20-25% from peak
- Taper week 2: Reduce volume by 40-50% from peak
- Race week: Reduce volume by 60-70% from peak
Intensity
Maintain intensity. Do NOT drop all hard running.
This is the most counterintuitive taper principle: you reduce volume dramatically but keep some intensity. Research shows that maintaining 1-2 short speed sessions per week during the taper preserves neuromuscular fitness and running economy.
Taper intensity sessions are short:
- 4-6 x 200m at 5K pace with full recovery
- 2-3 x 1 mile at race pace
- Strides after easy runs
These keep your legs sharp without creating fatigue.
Frequency
Maintain run frequency. Don't skip days.
If you normally run 5 days per week, continue running 5 days. Make the runs shorter rather than eliminating them. Complete rest days can make you feel stale and sluggish.
Tapering by TSB
The most effective way to manage a taper is watching your TSB (Training Stress Balance) — the difference between fitness (CTL) and fatigue (ATL).
Target TSB for race day
| Race | Target TSB |
|---|---|
| 5K | +5 to +15 |
| 10K | +10 to +18 |
| Half marathon | +12 to +20 |
| Marathon | +15 to +25 |
Longer races need higher TSB because the race itself creates more fatigue. You want to start with more in the tank.
Monitoring your taper
Check TSB daily during the taper. You should see:
- TSB trending upward throughout the taper
- CTL declining slightly (no more than 5-10% — fitness loss is minimal over 2-3 weeks)
- ATL dropping steadily as recent training stress decreases
If TSB isn't rising fast enough, you're not tapering aggressively enough. If it's rising too fast (you'll feel restless and antsy), you might have started the taper too early or reduced too much.
Recovery metrics during the taper
TSB tells the training load story. Recovery metrics confirm it's working at the physiological level:
- HRV trending upward: Your autonomic nervous system is recovering. This is the clearest confirmation signal.
- Resting heart rate declining: Your cardiovascular system is returning to fully recovered state.
- Sleep quality improving: Better sleep during the taper is common as physical stress decreases.
- Recovery scores (WHOOP/Oura) rising: Composite metrics should reflect improving readiness.
If TSB says you're fresh but HRV is still suppressed, something else is going on — poor sleep, life stress, or illness. The combination of training load and recovery data gives you the complete picture.
Pairform shows both on the same dashboard: TSB from your Strava training data alongside HRV and recovery from WHOOP or Oura. One glance tells you whether your taper is working.
The psychological challenge
The hardest part of tapering isn't physical — it's mental. Common taper anxieties:
"I'm losing fitness." You're not. Research shows CTL drops minimally over 2-3 weeks. The fitness you built over months doesn't evaporate in 14 days.
"I feel sluggish." Normal during the first few days of taper. Your body is shifting from "absorb training" mode to "repair and recover" mode. The sluggishness passes.
"One more hard workout won't hurt." It might. A hard session 5-7 days before race day can create enough fatigue to blunt the taper's benefit. Trust the process.
"I should do a long run to stay sharp." No. Your last long run should be 2-3 weeks before the marathon, 10-14 days before a half. After that, nothing longer than 60-70% of your normal long run.
"Everyone else on Strava is training harder." They might be training for a different race, on a different schedule, or making a mistake. Compare to your data, not theirs.
Race-specific taper adjustments
Marathon taper
The marathon requires the most aggressive taper because the race itself is the most damaging event:
- 3 weeks out: Last long run (18-20 miles). Begin volume reduction.
- 2 weeks out: Volume at 60% of peak. One tempo run at marathon pace (4-5 miles, not 10).
- Race week: Volume at 30-40% of peak. Two short shakeout runs with strides. Full rest 1-2 days before.
Half marathon taper
- 2 weeks out: Volume at 70% of peak. One quality session (tempo or intervals, shortened).
- Race week: Volume at 50% of peak. Strides on Wednesday or Thursday. Easy 20-minute shakeout the day before.
5K/10K taper
- 10 days out: Begin reducing volume by 20-30%.
- Race week: Volume at 50-60% of peak. One short sharpening session (6x200m at race pace) 3-4 days before race.
- Day before: Easy 15-20 minutes with 4 strides.
Putting it all together
The perfect taper comes down to three things:
- Reduce volume progressively (40-60% total reduction over 2-3 weeks)
- Maintain some intensity (short, sharp sessions to stay neurologically engaged)
- Monitor by the numbers (TSB trending toward target, HRV confirming recovery)
If you have the data, trust it over feel. The taper will feel wrong — that restless, antsy, "I should be doing more" feeling is exactly how you know it's working.
Want to taper by the numbers? Connect your devices to Pairform and watch your TSB, HRV, and recovery converge for race day — free.