Can I train with a cold, and when can I go hard again?
IOC experts: once nose and throat are nearly clear and there is no fever, aches, chest symptom or breathlessness, test 10-20 min at 60-70%; build after clean sessions. Opinion.
The IOC appointed an international group to review acute respiratory illness in athletes; this first part covers acute respiratory infections (colds, flu-like illness and lower respiratory infections), which make up most of it.
The group defines and classifies infections (suspected or confirmed; predominantly upper or lower), summarises epidemiology from commissioned reviews (about 4.9 infections per 1000 athlete days, roughly 1.8 a year per athlete), proposes a symptom-based severity scale (mild, moderate, severe) and sets out management, prevention and return to sport.
Return to sport is treated as a continuum from return to participation (the first session back) to full return at the pre-illness level, decided in four steps adapted from a risk framework used for injuries (StARRT): severity from symptoms; health risk from history, examination and, when indicated, tests; activity risk, first through an exercise challenge test and then by checking after every session; and risk tolerance.
For an asymptomatic or mild infection the athlete or coach runs this alone: a daily symptom checklist at rest, a challenge test at moderate intensity (60-70% of normal exercise intensity, response judged after 10-20 min, symptoms checked again immediately after and 24 h later), and the same checklist after each session before frequency, intensity or duration go up.
Moderate and severe infections go through a doctor, with a supervised laboratory test for severe ones; a severe infection means bed rest until regional and systemic symptoms have resolved. The authors call the challenge test before moderate-to-high-intensity training and the ongoing self-monitoring their two new contributions.
They say plainly that little research supports return-to-sport decisions, that the "neck check" was expert opinion, and that their severity indicators are not validated. Our reading: the most authoritative source on the subject, and an opinion; it contains no stage count, no heart-rate ceilings and no fixed days per stage.
Protocol
Design: consensus statement; n = not applicable (no study population; 21 authors).
Process (Methods): nominations circulated by the IOC Medical Commission and Scientific Department; nominees invited as "core" members (who drafted sections) or "corresponding" members (literature review, systematic and narrative reviews); the core group included a former Olympic athlete.Work began in September 2019; six subgroups (epidemiology and risk factors; infections; non-infective illness; acute asthma; effects on performance, complications and return to sport; nasal and vocal cord dysfunction), with a seventh on SARS-CoV-2 added in 2020 (published as part 3).Terminology agreed online in January 2021; draft discussed at a meeting in Lausanne on 11-12 October 2021; final edits over three months.
Evidence behind it: commissioned reviews by subgroups — incidence (124 studies, 128,360 athletes, 1990-2020), risk factors (48 studies, 19,390 athletes; the same paragraph also calls it a review of 24 studies), return to sport and time loss (REF-1234), multi-organ complications (too few studies to analyse), performance effects and prevention.
Funding and interests: no specific grant. Four authors hold IOC Medical and Scientific Department posts (Budgett, Engebretsen, Erdener, Soligard); no other competing interests declared.
Key Results
The four-step return to sport (section 9.3, Tables 6-8; expert consensus)
| Step | Asymptomatic or mild infection | Moderate infection | Severe infection |
|---|---|---|---|
| 1. Severity from symptoms (Table 4) | Mild: predominantly upper symptoms (blocked or runny nose, sneezing, altered or lost smell or taste, sinus pressure, sore throat, hoarseness), symptom score 0-3 of 10, under 3 days, fewer than 5 symptoms, no systemic signs | Lower respiratory symptoms (cough, difficult or fast breathing, chest pain with breathing or coughing) or regional symptoms (headache, red or watery eyes) without systemic ones; score above 3 to 7; 3-7 days; 5-9 symptoms; few, mild, transient (under 48 h) systemic signs | Systemic symptoms (fever, chills, excessive fatigue, general aches, rash) or signs of other organs (chest pain or tightness, dizziness, palpitations, breathlessness; severe abdominal pain, vomiting, diarrhoea); score above 7; over 7 days or relapsing; more than 10 symptoms |
| 2. Health risk | Athlete or coach completes checklist 1 daily (symptoms at rest, chronic disease risk factors) | Under a doctor; full assessment "can be considered"; CRP and blood count can be considered | Full clinical assessment strongly recommended; wider tests by suspected organ |
| 3. Activity risk | Self- or coach-run field test: 60-70% of normal intensity, judge after 10-20 min; stop and see a doctor on warning symptoms; recheck immediately after and at 24 h; checklist 3 after every session | Self-run or supervised laboratory test, the doctor's choice | Supervised laboratory test (e.g. modified Bruce protocol), exercise ECG recommended |
| 4. Risk tolerance | Final clearance once health and activity risk sit below an acceptable threshold; modifiers include pressure on the athlete, travel, competition timing, masking of symptoms and conflicts of interest | same | same |
Rest during the illness: in a mild or moderate infection normal daily activity is generally allowed, with a checklist before starting or resuming training; in a severe one, bed rest until regional and systemic symptoms have resolved and no active multi-organ involvement, then normal daily activity and a doctor's checklist before any training.
Warning symptoms that stop the challenge test or any later session (Tables 7-8): excessive fatigue, breathlessness, chest pain or discomfort, dizziness, palpitations or a racing heart (faster than normal, e.g. on a heart-rate monitor), muscle or joint pain, a higher effort for the same past load, "not feeling well"; at 24 h also very dark brown or red urine. Any of these: stop training and see a doctor or health professional.
Load progression: after a normal challenge test the athlete may raise frequency, intensity and duration, completing the post-session checklist after every session until the pre-infection level of training and performance is reached; no step size or timetable is given. The text says the process "may progress rapidly ... (from 1 day to a few days) or evolve gradually ... (few days to weeks)".
How long illness lasts (from [REF-1234]): about 20% of acute respiratory illnesses cost more than 1 day of training or competition; mean symptom duration 7 days; four studies reported days lost, 0 to about 8.
Incidence (commissioned review, 124 studies): 4.9 infections per 1000 athlete days overall (predominantly upper 5.9, combined upper and lower 2.8); non-elite 8.7 vs elite 4.2; about 1.8 a year per athlete against about 2.3 in the general population. Risk factors with strong associations: endurance sport, winter, high-intensity training, increased load, monotony, lack of tapering, altitude, competition periods, long-haul travel, vitamin D deficiency.
Complications: myocarditis or pericarditis after SARS-CoV-2 looked common in early small athlete cohorts but rare (under 3% or less) in larger studies; the commissioned review of multi-organ complications found too few studies to analyse.
Performance (summarised, not pooled): VO2max and lung function "seem to be robust" in a mild upper infection; a moderate to severe infection is more likely to impair performance; a recent infection 8 to 12 days before a race lowered the likelihood of starting it; in one cohort (REF-1001) completing more than 80% of planned training weeks went with 7-fold higher odds of success, and each week with modified training lowered the chance of a key goal by 26%.
Team setting: transmission is most likely in the first 3 to 4 days (SARS-CoV-2 up to 48 h before symptoms); consider isolation for at least 3-4 days after symptom onset before returning to team training.
Mechanisms
Authors' interpretation: the general symptoms of an infection come from a non-specific acute phase response, so symptoms cannot identify the pathogen but their type, duration and severity track the size of the inflammatory response, which is why severity is graded from symptoms.
Authors' interpretation: the risk on return is an adverse medical event during exercise (respiratory, cardiac or other organ involvement), concentrated in the roughly 20% of infections that are moderate or severe; a mild infection does not raise it or harm performance.
Measured (in the cited studies): myocarditis or pericarditis after SARS-CoV-2 was rare in larger athlete studies (under 3% or less).
Inference: the checklist items "A feeling of a higher level of effort for the same past exercise load" and a "racing heart (faster than normal e.g. on heart rate monitor)" are, in practice, the same signal as an easy-effort heart rate that runs high; the consensus uses them as stop-and-consult symptoms, not as a numeric gate.
Practical Application
Can I train with a cold, and when can I go hard again? IOC experts: once nose and throat are nearly clear and there is no fever, aches, chest symptom or breathlessness, test 10-20 min at 60-70%; build after clean sessions. Opinion.
Before every session while ill or recovering, run the rest checklist (consensus, Table 6): fever, chills, excessive fatigue, general muscle aches, difficult or fast breathing, chest pain or tightness, dizziness or a racing heart at rest, a moderate to severe cough, severe headache, persistent or severe nose or throat symptoms, persistent stomach symptoms, or not feeling well enough to exercise.Any one: no challenge test, see a health professional. None: the challenge test.
The challenge test is the gate to harder work (consensus): a familiar warm-up, walk, jog, ride or swim at 60-70% of normal intensity, judged after 10-20 min, with the warning-symptom list checked during, immediately after and at 24 h. The authors recommend it before any moderate- to high-intensity training after an infection.
Raise load only after a clean session (consensus): frequency, intensity and duration go up at the next session only if the post-session checklist was clear during, immediately after and 24 h after the last one. No step size or timetable is given; the base's 50-70% first week and 2-3-week rebuild (SYNTH-36) remain house practice.
Warning symptoms are a doctor, not a lighter week (consensus): chest pain or pressure, excessive breathlessness, palpitations or an irregular heartbeat, dizziness, excessive fatigue, effort higher than usual for the same load, dark brown or red urine after exercise — stop training and see a doctor. This gives the red-flag list in SYNTH-36 a named source; it remains expert opinion.
Fever is a systemic sign, never a mild one (consensus): the severity table lists fever, chills, general aches and excessive fatigue as systemic symptoms in the severe column (confirmed fever means a core temperature above 38 °C; only a few mild systemic signs lasting under 48 h are allowed within moderate), and fever at rest on the daily checklist means no challenge test and a health professional.For a severe infection the advice is bed rest until regional and systemic symptoms have resolved, then a doctor's checklist before training. That agrees with the base's "fever = stop"; the base's 24-48 h fever-free wait and "nothing hard for about a week" carry no number from this paper (base practice).
Headache is not an above-the-neck green light (consensus): the severity table counts headache as a regional symptom (moderate), with a chesty cough and breathing symptoms. Loss of smell or taste is listed as a mild upper symptom, although in one cohort cited by REF-1234 it went with a longer return.
Team sport: consider isolating for at least 3-4 days after symptom onset before returning to shared training, meals and transport (consensus).
Limitations
Expert consensus, untested. The authors write that little research supports return-to-sport decisions after an infection, that their severity indicators were proposed "by expert opinion" and that their validation "has not been established fully". The challenge test, the checklists and the four steps have not been evaluated in a trial; no Delphi round, vote or grading of evidence is described.
Written for clinicians. The self-run route is offered for asymptomatic and mild infections only; everything else assumes a doctor and, for severe infections, laboratory testing.
Internal numbers. Symptoms "resolve within 1 to 3 days" in the management section, "by 7 to 10 days in adults" in the clinical section and last a mean of 7 days in the return-to-sport section. The severity table puts fewer than 5 symptoms in mild, 5-9 in moderate and more than 10 in severe, so a count of exactly 10 has no class.The consensus says its commissioned review "included published studies up to August 2021"; that review searched to 31 July 2020 (REF-1234). The risk-factor review is described in one paragraph as both 24 and 48 studies.
Manuscript version. We read the accepted manuscript. In it the outcome of checklist 1 says an athlete should consult a health practitioner if the "athlete answered “No” to any symptoms (question 1)", where a yes is clearly meant; whether the published version corrects this was not checked. Figure 2 and the supplementary tables (including the list of investigations by organ) were not read.
Scope. Part 1 only; non-infective illness (part 2) and SARS-CoV-2 (part 3) are separate papers not in the base.
How this entry was checked and changed
Why this level
the rubric's "major consensus / position statement" line (A), graded one step down, as for REF-1071 and REF-776, because its recommendations describe themselves as expert opinion. Not its A+ line ("governing-body consensus built on systematic review"): commissioned systematic reviews supply the incidence and time-loss figures (REF-1234), but the return-to-sport steps, the severity classification and the exercise challenge test are, in the authors' own words, built where "there is little research available", with severity indicators suggested "by expert opinion" and not validated. Read from the full text of the accepted manuscript (University of Pretoria repository), not the typeset version; Figure 2 (the decision flow chart, an image) and the online supplementary tables were not read
Full text (checked 2026-10-27)
Draft discussed at a meeting in Lausanne "on 11 to 12 October 2021"; "Final edits were completed in a 3-month period after the meeting" (full text)
"Approximately 50% of all medical consultations at these events relate to acute illness in athletes" (full text)
Pooled incidence of all acute respiratory infections "4.9 per 1000 athlete days"; "~1.8 ARinf per athlete per year (in comparison to ~2.3 in the general population)" (full text)
The commissioned review "identified a total of 54 studies representing 31,065 athletes. Only 4 studies reported actual days until RTS following ARill, ranging from 0 to about 8 days. The mean symptom duration for all ARill was 7 days" (full text)
The commissioned review "included published studies up to August 2021" (full text)
Self-run exercise challenge test: "Choose a moderate exercise intensity (60-70% of normal exercise intensity)"; "Assess your response (how you feel) after 10-20min of exercise"; monitor "immediately after exercise and 24 hours after exercise" (full text)
Severity scale: symptom score 0-3 (mild), >3-7 (moderate), >7-10 (severe); total symptoms <5, 5-9 and >10; systemic signs include "Confirmed fever (Core temperature >38oC)" (full text)
"Most ARinf in athletes (>80%) can be classified as mild" (full text)
Myocarditis or pericarditis after SARS-CoV-2 "was found to be rare (< 3% or less)" in larger studies (full text)
"In most cases symptoms of ARinf resolve within 1 to 3 days" (management section) and symptoms "resolve by 7 to 10 days in adults" (clinical section) (full text)
A recent infection "(8 to 12 days prior to a race)" reduced the likelihood of starting; success "increased by 7-fold in athletes able to complete >80% of planned training weeks"; each week of modified training "reduced the chances of achieving a key sports performance goal by 26%" (full text)
"Consider isolation of minimum of 3-4 days after symptom onset before return-to-training in a team setting" (full text)
Competing interests: four authors work for the IOC Medical and Scientific Department; "The authors have not declared a specific grant for this research" (full text)