How many training days does a cold usually cost?
Usually a day or less: pooled from 11 studies, 20% of athletes' respiratory illnesses cost more than a day; symptoms lasted about 7 days. Observational, mostly undiagnosed, no COVID-19.
Snyders et al. searched three databases for studies from January 1990 to July 2020 that reported, in athletes or military recruits aged 15 to 65 with an acute respiratory illness, the days until return to sport, the share of illnesses that cost more than a day of training or competition, or how long symptoms lasted.
Of 767 records, 54 studies (31,065 participants, 67% male) were included. No study reported days until return to sport as such; four reported days lost, which the authors used as a proxy (0 to 8.5 days). Pooled across 11 studies (18,730 participants), 20.4% of illnesses cost more than a day; pooled across 29 studies, symptoms lasted 7.1 days.
There was no evidence of a difference in time loss between suspected and undiagnosed or upper and general illness, nor in symptom duration between undiagnosed, suspected and laboratory-confirmed illness.
In the discussion the authors cite two later studies of return to sport outside their window: in rugby players, infections cost about 10 times as many days as non-infective respiratory illness; in 84 athletes, COVID-19 took a median 30 days to return against 10 for other infections; and in that cohort some symptoms above the neck (headache, loss of smell), with excessive fatigue and fever or chills, went with a longer return, which the authors say does not support the "neck check".
Our reading: most respiratory illness in athletes is brief and costs little training; the 18-day COVID-19 median in REF-376 belongs to a different illness, mostly mild in that cohort but managed under medically supervised pandemic-era return; and the review cannot say how long the return should take, because the studies did not measure it.
Protocol
Search: PubMed, EBSCOhost and Web of Science (Core Collection), 1 January 1990 to 31 July 2020, English, original research only; two independent reviewers (CADIMA), cross-checked by two more.
Eligibility: male or female athletes at any level, or military recruits in training, aged 15-65, with a suspected or confirmed respiratory infection or mixed respiratory illness, reporting days lost or to return, the share of illnesses with more than 1 day lost, or symptom duration. Chronic illness and purely non-infective illness (allergic rhinitis, asthma) excluded. From randomised trials only the control groups were used.
Included: 767 records, 68 full texts, 54 studies; n = 31065 participants (31 065 in the paper), 10,706 days of surveillance, 67% male and 33% female. Time-loss analysis: 11 studies, 18,730 participants, 1,966 surveillance days. Symptom-duration analysis: 29 studies, 1,428 participants, 6,212 surveillance days (one study excluded because it enrolled only people with symptoms over 72 h).
Classification: by diagnostic method (self-report alone, self-report with a validated algorithm, physician review of self-report, clinical diagnosis, laboratory-confirmed pathogen) into undiagnosed illness, suspected infection or confirmed infection; and by region (upper, lower, general).
Quality: modified Downs and Black tool (score out of 13; included studies 7 to 13, fair to excellent); Oxford level of evidence 1b to 3b.
Analysis: random-effects (DerSimonian-Laird) pooled proportion of time-loss illness and pooled mean symptom duration; I²; subgroup differences judged by overlapping 95% CIs; Egger tests and funnel plots. Days lost were summarised but not pooled.
Funding and interests: partly funded by the IOC Research Centre of South Africa; the first author held a South African Medical Research Council scholarship. The senior author led the IOC consensus that commissioned the review (REF-1233).
Key Results
| Outcome | Studies | Pooled result (95% CI) |
|---|---|---|
| Illnesses with more than 1 day lost, all | 11 (18,730 participants) | 20.4% (15.3 to 25.4), I² 69.6% |
| Suspected infection / undiagnosed illness | — | 17.9% (11.8 to 23.9) / 21.6% (13.6 to 29.7) |
| Upper / general (upper and lower) | — | 18.4% (10.7 to 26.1) / 21.3% (14.1 to 28.5), I² 72.3% |
| Symptom duration, all | 29 (1,428 participants) | 7.1 days (6.2 to 8.0) |
| Undiagnosed / suspected / confirmed | — | 6.8 (4.8 to 8.7) / 7.0 (6.0 to 8.0) / 8.3 (6.2 to 10.3) days, I² 99.2% |
| Infection by diagnostic method: all / self-report with algorithm / physician / laboratory | — | 7.2 (6.3 to 8.2) / 6.7 (5.7 to 7.8) / 8.0 (4.7 to 11.3) / 8.3 (6.2 to 10.3) days, I² 99.3% |
| Days lost, as a proxy for days to return | 4 (not pooled) | upper infection 1.7 ± 2.3 and 3.5 ± 5.0 days; lower infection a mean of 2.5 days (four episodes in one study); in one study 0 days for upper infection and up to 7 days for infection with systemic symptoms |
Training effects (6 studies, not pooled): 42%-70% of participants said the illness impaired training; 14%-19% reduced volume or intensity; weekly load fell 24% in one study; training was modified in up to 50% and up to 31% of elite athletes stopped all training in the acute phase; in endurance athletes training was reduced for 3.4 ± 5.1 days.
Pathogens (one Winter Olympic team, 20 athletes with a cold): mean symptom duration 8.7 days with RSV A, 4.0 with metapneumovirus, 13.5 and 18.0 with coronaviruses 229E and OC43. In two prospective studies a pathogen was found in about 30% of infections, most often rhinovirus.
Studies after the review's window (discussion only): rugby players over five seasons — infections cost more days to return than non-infective respiratory illness (ratio 10.4, 95% CI 4.3 to 25.3), lower infections most; 84 athletes — median return 30 days with confirmed COVID-19 against 10 days with other infections; median symptom duration 9-10 days for nose and throat, 14 for chest and neck, 11 for systemic symptoms.
Numbers that do not add up: (1) The abstract says "4 studies reported days until RTS (range: 0–8.5 days)"; the Results say no article reported days until return to sport and use days lost from four studies instead, and no reported value is 8.5 — it equals 3.5 + 5.0, one study's mean plus one SD (our arithmetic).(2) The abstract's conclusion, "In 80% of ARill in athletes, no days were lost", restates an outcome defined as more than 1 day lost, so the 79.6% (our arithmetic) includes illnesses that cost one day (our reading). (3) The discussion calls the four days-lost studies "suspected upper ARinf", but one of them reported lower infection (2.5 days).
Mechanisms
Measured: no evidence of a difference in the share of illnesses costing more than a day between suspected and undiagnosed illness or between upper and general illness, nor in symptom duration between undiagnosed, suspected and confirmed illness (overlapping CIs).
Authors' interpretation: a low share of time-loss illness means most respiratory illnesses in athletes are not severe; days to return probably depend on the pathogen and on severity (localised upper, regional lower, or with multi-organ involvement).
Inference: symptoms lasting about 7 days while about 80% of illnesses cost a day or less means most athletes train through part of a cold. The review did not measure whether that was harmless, and it cannot tell training through mild symptoms from training through a systemic illness.
Practical Application
How many training days does a cold usually cost? Usually a day or less: pooled from 11 studies, 20% of athletes' respiratory illnesses cost more than a day; symptoms lasted about 7 days. Observational, mostly undiagnosed, no COVID-19.
Reassurance with a boundary: an ordinary cold rarely costs more than a day (A-, observational studies; how many cost a week was not measured); the 18-day median after COVID-19 in REF-376 (mostly mild, under medically supervised pandemic-era return) and 30 days in the COVID-19 cohort cited here (more severe disease) belong to a different illness.Not from this paper; the base's own practice: fever or any below-the-neck symptom still means stop, and chest pain, palpitations or breathlessness out of proportion mean a doctor (SYNTH-36, SYNTH-30).
The neck check is a convention, not evidence: the authors write that there is no scientific evidence for it, and one later cohort (84 athletes, cited here) found headache and loss of smell — symptoms above the neck — alongside excessive fatigue and fever or chills linked to a longer return.Inference, not base practice (the base's neck check does not single these out): treat a headache or loss of smell as more than a head cold (REF-1233 counts headache as a moderate, regional symptom).
Symptom length is not the return date: symptoms averaged about 7 days while most athletes lost a day or less, and the authors note symptom duration does not necessarily predict days to return. How long to rebuild is not answered here; REF-1235 measured it in confirmed infections.
Limitations
What was measured is not return to sport. No study measured days to full return; four reported days lost, and in some studies time loss was a physician's estimate at the first visit. Whether time was lost to the illness or to advice not to train was not recorded.
Mostly undiagnosed illness. Most studies diagnosed from symptoms; a pathogen was found in about 30% of infections in two prospective studies, so "confirmed" subgroups are small.
Heterogeneity and bias. I² 69.6% for time loss and over 99% for symptom duration; Egger tests and funnel plots showed a higher risk of publication bias for symptom duration. English-language studies only.
No COVID-19. The search ended on 31 July 2020; the COVID-19 data in the discussion come from three studies outside the review.
Reporting. The abstract's "4 studies reported days until RTS" and "no days were lost" overstate the Results (see Key Results). The I² of 69.6% is given for both the overall and the subgroup time-loss analysis.
Interests. Partly funded by the IOC Research Centre of South Africa; written by a subgroup of the IOC consensus group whose senior author led the consensus (REF-1233).
How this entry was checked and changed
Why this level
the rubric's A- line (SR/MA with serious heterogeneity). Not A: the inputs are surveillance and cohort studies rather than controlled trials, heterogeneity is substantial for time loss (I² 69.6%) and extreme for symptom duration (I² 99.2-99.3%) with significant publication bias for duration, and the headline question, days to return, rests on four unpooled studies that report days lost as a proxy. Read from the full text (published version, open access, CC BY-NC 4.0, via the University of Pretoria repository); the online supplements (study tables, quality scores, funnel plots) were not read
Full text (checked 2026-10-27)
Abstract: "767 articles were identified; 54 were included (n=31 065 athletes). 4 studies reported days until RTS (range: 0–8.5 days)" (full text)
"No articles specifically reported the days until RTS after ARill"; days lost due to upper infection "1.7±2.3 days" and "3.5±5.0 days of training lost"; lower infection "mean of 2.5 days per illness episode" (full text)
In one study "0 days were lost" with upper infection, while with systemic infection "up to 7 training/competition days were lost" (full text)
Time loss of more than 1 day: "20.4% (15.3% to 25.4%) (I2=69.6%)" from 11 studies with "18 730" participants (full text)
Suspected infection "17.9%; 11.8–23.9"; undiagnosed illness "21.6%; 13.6–29.7"; general illness "21.3%; 14.1–28.5" (I2=72.3%) (full text)
Symptom duration "7.1 (6.2 to 8.0) days" from 29 studies with 1428 participants; undiagnosed "6.8: 4.8 to 8.7", suspected "7.0: 6.0 to 8.0", confirmed "8.3: 6.2 to 10.3" (I2=99.2%) (full text)
Participants: "31 065 athletes", "10 706 days of surveillance", "67% males and 33% females" (full text)
Training: "42%–70% of participants" reported impaired training; "up to 31% of elite athletes" ceased all training in the acute phase; endurance athletes' training "reduced for 3.4±5.1 days" (full text)
Rugby: days to return ratio for infection vs non-infective illness "10.4; 95% CI 4.3 to 25.3"; 84 athletes: median days until return "(30 days vs 10 days)" for COVID-19 vs other infections (full text)
"There is no scientific evidence for these guidelines and the validity of the 'neck check' as a guide for RTS has been challenged"; "These early data do not support the 'neck check'" (full text)
PROSPERO registration "CRD42020160479"; funding "Partially supported by funding from the IOC Research Centre of South Africa" (full text)