REF-1235 · Jooste et al., 2026 · British Journal of Sports Medicine · Paper · PubMed

After a cold or the flu, how long until I am back to full performance?

In 114 lab-confirmed infections: training resumed after a median 3.5 days, full performance after 11. Flu, COVID-19 and severe illness took longer. Observational.

Blimited evidenceMeasured on trained to elite athletes

Jooste et al. followed 114 acute respiratory infections in athletes, each confirmed and assigned a pathogen by multiplex PCR, and graded each as mild, moderate or severe on the IOC consensus criteria. They recorded the days to three milestones: return to training, return to full training and return to full performance.

The median was 3.5 days to return to training, 8 to full training and 11 to full performance. In Cox models, amateurs took longer than professionals at every milestone (hazard ratios 0.51-0.59, where a ratio below 1 means a slower return), influenza and SARS-CoV-2 took longer than rhinovirus (0.11-0.23), and severe illness took longer than mild or moderate illness (0.17-0.31).

The pathogen difference held within mild-to-moderate and within severe illness. The authors conclude that clinical severity remains useful for return-to-sport decisions and that identifying the pathogen may add predictive value.

Our reading: the first measured gap in the base between restarting training and full performance after an illness — about a week on the medians — in a small cohort read from the abstract only.

Protocol

Design (abstract): prospective cohort; n = 114 confirmed acute respiratory infection cases among athletic individuals.
Pathogen: multiplex PCR.
Severity: mild, moderate or severe per the IOC consensus (REF-1233).
Outcomes: days to return to training (RTT), return to full training (RTFT) and return to full performance (RTFP).
Analysis: Cox regression (hazard ratios) of the outcomes against demographics, level of sport participation, pathogen group and severity.
Not given in the abstract: setting, country and recruitment period; the number of athletes (whether anyone contributed more than one infection); sports, ages and sex; the day from which milestones were counted; how full training and full performance were defined and recorded; whether the models were adjusted for each other's factors; confidence intervals; the size of each pathogen and severity group.
Funding and interests: competing interests "None declared" (PubMed record); funding not given in the abstract; Crossref lists the Academy of Finland, the IOC (Research Centre of South Africa), the SAMRC Division of Research Capacity Development and Kuopio University Hospital state research funding. The senior author led the IOC consensus whose severity scale is used here (REF-1233).

Key Results

MilestoneMedian days (IQR)
Return to training3.5 (0-7)
Return to full training8 (6-11)
Return to full performance11 (7-14)

Hazard ratios (below 1 = slower return in the first-named group; the abstract gives each as a range without saying what it spans, probably the three milestones):

ComparisonHazard ratiop
Amateur vs professional0.51-0.59≤0.03
Influenza and SARS-CoV-2 vs rhinovirus0.11-0.23≤0.003
Severe vs mild and moderate0.17-0.31<0.0001
Influenza/SARS-CoV-2 vs rhinovirus, within mild/moderate illnessRTT 0.35, RTFT 0.05, RTFP 0.06<0.05
Influenza/SARS-CoV-2 vs rhinovirus, within severe illnessRTT 0.23, RTFT 0.21, RTFP 0.13≤0.01
A number to read with care: within mild-to-moderate illness the hazard ratios for full training and full performance (0.05 and 0.06) lie outside the overall pathogen range (0.11-0.23). Stratified estimates can be more extreme, but with no confidence intervals or group sizes in the abstract their precision cannot be judged.
Our arithmetic on the medians: full performance came about 7.5 days after the median return to training (11 − 3.5). Medians of different milestones are not a median of each athlete's gap, so this is an approximation.

Mechanisms

Measured: severe illness, influenza or SARS-CoV-2 (against rhinovirus) and amateur status each went with a slower return at all three milestones.
Authors' interpretation: severity at presentation, the pathogen and the level of sport participation are factors in return to sport; clinical grading of severity stays valuable, especially where testing is not available, and pathogen identification may refine the decision.
Inference: why amateurs returned more slowly is not explained in the abstract; less medical support, less pressure to return, more severe or different infections, or different milestone definitions could each contribute, and the abstract does not say whether severity and pathogen were adjusted for.

Practical Application

After a cold or the flu, how long until I am back to full performance? In 114 lab-confirmed infections: training resumed after a median 3.5 days, full performance after 11. Flu, COVID-19 and severe illness took longer. Observational.
Expect a lag after the first session back (B, observational, from the abstract): on the medians, full training came about 4.5 days and full performance about 7.5 days after training resumed (our arithmetic). Inference, not from the abstract (the base's own practice in SYNTH-36): a first week back below full performance is the expected course, not lost fitness.
The pathogen and the severity matter more than the calendar: influenza and SARS-CoV-2 took longer than rhinovirus even within the same severity class, and severe illness (on the IOC scale: fever, chills, general aches, excessive fatigue or signs beyond the airways; REF-1233) took longer than mild or moderate. Not from this paper; the base's own practice: a systemic illness gets the slower track in SYNTH-36.
Amateurs, not only elites, take time: amateurs returned more slowly than professionals (hazard ratios 0.51-0.59). The reason is not given in the abstract.
Scope: every infection was PCR-confirmed and the athletes' sports and levels are not given in the abstract; the numbers describe a mix of severities and say nothing about whether a faster or slower return would have been better.

Limitations

Read from the abstract. Methods, group sizes, confidence intervals, the starting day for the milestones and the definitions of full training and full performance were not available.
Small observational cohort. 114 infections split by pathogen and severity leave small subgroups; associations, not causes; no comparison with an uninfected break of the same length, so the cost of the illness itself and the cost of the days off are not separated.
Selected infections. Only PCR-confirmed infections were included; untested colds, which REF-1234 suggests are the usual case, may run shorter.
Interests. No competing interests declared; the senior author also led the consensus that defined the severity scale used here (REF-1233).
How this entry was checked and changed
Why this level

from the abstract; small cohort (n = 114 infections; the number of athletes is not given in the abstract), associations only. Closed access: no PubMed Central copy, the publisher's site is behind a bot check, and OpenAlex lists no repository copy, so the methods, confidence intervals and adjustment set could not be read