Olfactory acuity, which includes detection thresholds, identification and appreciation/intensity, seems to decline with aging, obesity, and various neurological disorders. Knowing that the sense of smell influences energy intake, the interest in protecting this sense is constantly increasing. Physical activity might be a key intervention to counteract the loss of olfactory function. This systematic review aims to explore the literature on the effect of physical activity on olfactory acuity. The search strategy consisted of using index terms and keywords in MEDLINE, EMBASE, EBM Reviews - Cochrane Central Register of Controlled Trials, CINAHL, SPORTDiscus, and Web of Science search engine. Data from 17 studies that include 10 861 participants revealed that physical activity has improved olfactory thresholds, identification, and intensity. More precisely, chronic physical activity seemed to have better effects on olfactory components than acute practice. Even though this review clarified evidence about the effect of physical activity on the sense of smell, better methodological consistency is needed across studies such as standardized experimental conditions, the time of the day data are collected, and similar relative energy intake between participants to produce more robust results.

The authors have declared no competing interest.

Mathieu Cournoyer and Alexandre-Charles Gauthier received scholarships from the University of Montreal. Fabien Dal Maso is a research scholar from the Fonds de recherche du Quebec - Sante (Junior 1). Marie-Eve Mathieu holds a Canada Research Chair (Tier 2).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Six databases were used to perform the search: Medline (1946-present), Embase (1974-present), EBM Reviews - Cochrane Central Register of Controlled Trials (1991-present), CINAHL Plus with Full Text (1937-present), SportDiscus with Full Text (1930-present) and Web of Science (1945-present). The last research was performed on December 22, 2021. The following keywords were used to search the concept of physical activity: "aerobic training" OR exercise* OR "physical activity" OR "physical training" OR "resistance training" OR sport* OR "strength training" OR "weight training" OR weightlifting OR "weight lifting" OR running OR football OR hockey OR athletes OR exertion OR "athletic performance". For olfaction, the following keywords were used: odor OR odour OR aroma OR fragrance* OR smelling OR smell OR olfactory OR olfaction OR normosmic OR normosmia OR hyposmic OR hyposmia OR anosmic OR anosmia OR odorant* OR sniff OR sniffing. Included studies had to meet the following inclusion criteria: (1) investigate the effect of PA on olfactory acuity; (2) involving humans, both adults and children. On the other hand, studies were not included if (1) olfactory acuity had changed following head trauma or surgery; (2) studies were not completed or accepted in peer-review journals; (3) studies were written in a language other than English or French.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.

Yes

All data produced in the present work are contained in the manuscript