Marathon muscle-damage markers take about a week or more to settle, and the build-up adds injury risk, so a winter race fits a triathlon season best when it is early, modest and recovered from
Interpretation
Recovery data are consistent but small and from runners: CK raised up to 96 h and back to baseline after 144 h, LDH after 192 h, CRP still raised at 192 h in 86 marathoners (Bernat-Adell 2021); easy running from 48 h didn't slow recovery in 64 finishers, 54 of them men (Martínez-Navarro 2021); runners slowing more than 15% had more muscle damage (Del Coso 2013, 40 runners). Build-up risk: novice runners have 17.8 vs 7.7 injuries per 1000 h in recreational runners (Videbæk 2015); higher volume and longer long runs predict faster half and full marathons without more injuries (Fokkema 2020, 997 runners). Illness before a race was linked to more illness after (Ekblom 2006, 1,694 runners). No study has tested whether a winter marathon helps or harms a triathlon season; that part is inference.
Practical implication
Prefer a half marathon in December or January, or a full marathon only with a solid running history and plenty of time before the first key triathlon; build run volume gradually, keep easy swim and bike training, run easy from about 48 hours after but hold hard sessions back until fully recovered, bearing in mind markers take about a week to settle, and skip or downgrade the race if ill. Extrapolated from runner studies, not triathletes.
Sources
6 sources, independently verified.
Blood sampled before, immediately after and 24-192 h after a marathon. Creatine kinase raised up to 96 h and back to baseline after 144 h; LDH raised throughout and back to baseline after 192 h; high-sensitivity troponin T raised at 24 and 48 h, baseline after 96 h; CRP still raised at 192 h. Higher race energy expenditure linked to higher markers. Markers, not functional recovery.
Runners allocated at the finish to easy running, elliptical training (40 min at about first ventilatory threshold heart rate at 48, 96 and 144 h) or rest. No differences in CK or LDH recovery; at 96 h squat jump was 108% of pre-race in the running group vs 101% with rest. Returning to easy running at 48 h did not harm muscle-damage recovery up to 8 days. Small, mostly male; easy sessions only.
Pace fell from 3.5 m/s in the first 5 km to 2.9 m/s in the last 5 km. Runners slowing by more than 15% had higher post-race myoglobin (1,318 vs 623 µg/L) and LDH, and higher CK (564 vs 363 U/L, P = 0.07), with similar body-mass loss (about 3%) and body temperature. Observational: association, not causation.
A longest training run under 25km was associated with a slower marathon (+13.44 min vs the 30-35km reference group), but runs beyond 35km showed no further performance benefit (-4.86min, not significant) and were not associated with higher injury odds (OR 1.01). 55.1% of marathon runners in the cohort had a new running-related injury, but no training characteristic — including longest run — was associated with that injury rate. Evidence for a performance floor, not a ceiling, below which longer runs help.
13 studies. Pooled injury incidence 17.8 per 1000 h of running in novice runners (95% CI 16.7-19.1) and 7.7 per 1000 h in recreational runners (6.9-8.7); individual studies ranged from 2.5 to 33.0. Not triathletes.
Self-reported infections in the 3 weeks before (17%) and after (19%) the race; 33% of runners ill beforehand reported an infection afterwards vs 16% of those who were not. Training volume over 6 months unrelated. Did not support a general increase in infection rate; suggests hard exercise soon after infection may be a problem. Self-report survey.