Three days after an Ironman, stairs stop hurting. On day five the bike starts to look appealing. By day ten everything feels normal and the intervals come back. That is when most of the autumn injuries and infections begin.
The subjective sense of being recovered and the actual repair of tissue run on two different timelines. Blood work shows the gap clearly.
What the blood shows 19 days after the finish
The classic study here was published by Neubauer, König and Wagner in the European Journal of Applied Physiology in 2008. They took blood from 42 well-trained triathletes, all men, two days before the race, immediately after the finish, and then at 1, 5 and 19 days.
Everything rose straight after the finish: leukocytes, myeloperoxidase, elastase, cortisol, creatine kinase (CK), myoglobin, interleukin IL-6, IL-10 and hs-CRP. Testosterone fell.
After five days the muscle damage markers were still altered. At 19 days some markers of muscle damage and systemic inflammation remained elevated.
The authors’ conclusion is unambiguous and worth remembering: given the observed muscle repair and inflammatory processes, at least two to three weeks of active recovery are indicated before returning to more intense training.
Not two days off and back to it. Two to three weeks, as a minimum rather than as advice for the cautious.
Data from Kalmar: heart, kidneys and a difference between the sexes
A more interesting data set comes from the course where Jonas Schomburg rode 7:22:57 and broke the record this year. Swedish researchers studied 30 finishers of IRONMAN Kalmar, 15 women and 15 men, and published the results in Läkartidningen in 2016.
Elevated after the finish were troponin T, creatine kinase, myoglobin, NT-proBNP and creatinine. In almost all of the group these returned to normal within 5 to 8 days.
Two details from that study are worth knowing.
First, in every participant but one the troponin T pattern matched the picture that would signal a heart attack in a clinical setting. The authors note honestly that it is still unknown whether the rise means genuine damage to the heart muscle or is a benign consequence of a temporary change in cell membrane permeability. It is not cause for panic, but an athlete who ends up in an emergency department with chest pain in the week after a race should tell the doctor they have raced an Ironman. It changes how the result is read.
Second, the women tolerated the effort better. After the finish they had significantly lower myoglobin and creatinine values than the men.
One further finding says something about preparation itself: a completely normal ECG was recorded in only 26.7% of the women and 6.7% of the men in that group.
The creatinine matters. It means the kidneys were also working at their limit, which is an argument against reaching for non-steroidal anti-inflammatories for sore legs in the first days after a race.
Why the two timelines diverge
DOMS peaks at 24 to 72 hours and then goes. Muscle fibre repair, the resolution of inflammation, glycogen restoration and the return of hormonal balance all run to their own, longer rhythm.
The effect is treacherous. Feeling good reads as being ready. Meanwhile the immune system is only just recovering, and the muscles have five days of active CK behind them. Interval training in that window lands on tissue that has not finished repairing. That is why strains and upper respiratory infections show up in the second and third week after a race rather than the first.
The first two weeks in practice
What follows is coaching practice, not a study protocol. The research says how much, not how. Long-distance coaches agree on a few points.
Days 1 to 3. No training with a purpose. Walking, sleep and food. No ice baths, because there is already plenty of inflammation to resolve. Protein and carbohydrate in normal amounts, since this is not the moment for a calorie deficit.
Days 3 to 7. Movement without joint loading: easy swimming, zone 1 riding and walking. One criterion applies: more energy after the session, not less.
Days 7 to 14. Light running comes back, short and on soft surfaces. Volume around 50 to 60% of the pre-race block is about right. No intensity, however good the legs feel. No FTP test to check whether the fitness is still there.
After two weeks single harder efforts can start to go back in, provided sleep has returned to normal, resting heart rate is back at its usual level, and HRV is not sitting a week below average.
If the season ended at that Ironman, the break can comfortably run longer. Nothing is lost. A three week break in August will not take away next year’s fitness. Going into autumn with an unhealed Achilles tendon will take away February and March.
Three signs of coming back too fast
- Resting heart rate stays a few beats above normal for more than a week after the race.
- Heart rate will not climb on easy sessions at normal effort. That is a tired autonomic nervous system, not freshness.
- Another throat or sinus infection in the second or third week after the finish. That is usually not a coincidence.
Any of the three means the same thing: go back a week in the plan.
More on this: Polar Vantage M3 Review: AMOLED, Dual-Band GPS. Racelify lists triathlons worldwide with dates and organiser links.