Formula, in endurance
Race-Week Taper Formula + Carb Loading (Burke)
Tapering reduces training volume sharply while keeping intensity and the number of sessions. Bosquet et al.'s 2007 meta-analysis (27 studies) found the best results from a taper of about 2 weeks that cuts volume progressively by 41-60% with intensity and frequency unchanged. Cutting intensity instead of volume undoes most of the gain. The taper withdraws fatigue, not fitness.
4 variables. Published May 14, 2026. Updated Oct 5, 2026. By AI Fit Hub.
taper_week_volume = peak_volume × (1 − average_cut × shape_week)
average_cut = 0.41 (5K) to 0.60 (ultra), inside the 41-60% range
shape = [1] for 1 week, [0.8, 1.2] for 2 weeks, [0.7, 1.0, 1.3] for 3 weeks
intensity and run frequency kept throughout Variables
peak_volume
Peak training volume
Highest weekly volume during build phase (km, hours, or distance equivalent). The taper starts from here.
average_cut
Average volume cut
Share of peak volume removed, averaged over the taper weeks: 0.41-0.60 per the meta-analysis. The calculator uses 41% for a 5K up to 55% for a marathon and 60% for an ultra.
shape_week
Weekly shape factor
Spreads the average cut so it deepens toward race day; the factors average 1, so the weeks average the headline cut.
intensity
Training intensity
Pace, power, or RPE of quality sessions. Keep it at race intensity through the taper; cut how long each session is, not how hard. Cutting intensity (the common mistake) erodes fitness; cutting volume preserves it while clearing fatigue.
Step by step
- 1
Identify peak weekly volume from your build phase (the highest week, not average).
Marathon training peaked at 80 km/week.
- 2
Choose taper length. Marathon: 14 days. Half: 10 days. 10K: 7 days. 5K: 5 days.
Marathon → 14-day taper, starting 2 weeks out.
- 3
Compute weekly volume: for a 2-week marathon taper the cut is 0.8 × 55% = 44% two weeks out and 1.2 × 55% = 66% in race week (the race not counted).
Two weeks out: 80 × 0.56 = 44.8 km. Race week: 80 × 0.34 = 27.2 km.
- 4
Keep intensity workouts. Hold marathon pace tempo + intervals through Week −2; do one short tempo Week −1.
Week −2: 8 km @ marathon pace + intervals. Week −1: 4 km @ marathon pace + jog easy.
- 5
Race week: 2-3 easy runs + 1 short tempo. Day −2: 4 km easy. Day −1: rest or 20-min jog.
Mon easy 6 km, Tue tempo 4 km, Wed easy 5 km, Thu jog 30 min, Fri rest, Sat shake-out 3 km, Sun race.
Worked example
Marathon runner peaking at 80 km/week, race in 14 days
Peak volume
80 km/week
Taper length
2 weeks
Average cut (marathon)
55%
Two weeks out (days 14-8): 80 × (1 − 0.44) = 44.8 km, longest run 45% of that = 20.2 km. Intensity: marathon-pace tempo + an interval session, both shorter. Race week (days 7-1): 80 × (1 − 0.66) = 27.2 km plus the race itself, longest run 12.2 km. Intensity: one short race-pace session. Average cut across the two weeks: (44% + 66%) / 2 = 55%.
Expected outcome: a small but real gain over racing without a taper. Common mistake: cutting volume to 80% and intensity to 60% — that's a 'detraining mini-block' rather than a taper. Keep the spice, lose the bulk.
Common variations
Run the numbers next
- Cardio Running Pace Calculator
Calculate pace per km and mile and project race finish times from one run.
- Cardio Race Time Predictor
Race Time predictor: predict finish times across 5K, 10K, half marathon, and marathon from any known race result using Riegel's formula.
- Cardio Marathon Pace + Elevation Calculator
Convert a target marathon time on a hilly course into the flat-equivalent pace you actually need.
Questions people ask next
How much should you cut training volume during a race-week taper?
Reduce training volume by 41-60% of your peak, with most studies clustering around a 50% cut. Beginners can take more off (60-70%) while elites take less (30-40%). The key is to cut volume, not intensity: hold pace, power, or RPE at 90-100% of race intensity throughout the taper.
How long should the taper be for a marathon vs a half marathon?
Evidence supports roughly 8-14 days for a marathon, 7-10 days for a half marathon, and 4-7 days for a 5K-10K. The step-by-step guidance uses 14 days for a marathon, 10 days for a half, 7 days for a 10K, and 5 days for a 5K.
How much faster does tapering make your race, per Mujika and Padilla?
Mujika and Padilla's 2003 meta-analysis (n=27 studies) found that a 41-60% volume reduction over 8-14 days produces about a 3% performance improvement, and Bosquet et al. (2007) confirmed the ~3% figure. Cutting intensity instead of volume undoes most of that gain.
What does Burke et al. (2011) recommend for carb loading during the taper?
Burke et al. (2011) supports carb-loading at 7-12 g/kg of body weight per day for 1-3 days before the race. It pairs well with the taper because reduced training means less glycogen turnover, so the loaded glycogen stays in the muscle.
What is the most common tapering mistake?
Cutting intensity along with volume. Dropping volume to ~80% and intensity to ~60% creates a detraining mini-block rather than a taper, eroding fitness instead of just clearing fatigue. The taper should withdraw fatigue, not fitness, so keep the hard sessions and shed the easy bulk.
Sources
- Mujika & Padilla (2003). Scientific bases for precompetition tapering strategies. , Medicine & Science in Sports & Exercise — review of tapering strategies
- Bosquet et al. (2007). Effects of tapering on performance: a meta-analysis. , Medicine & Science in Sports & Exercise — meta-analysis of 27 taper studies
- Burke et al. (2011). Carbohydrates for training and competition. , Journal of Sports Sciences — carb-loading dose during taper
- Pyne et al. (2009). Peaking for optimal performance: research limitations and future directions. , Journal of Sports Sciences — practical taper recommendations