Table 2.
Evidence‐based interventions, modifiable lifestyle and environmental factors that have a positive impact on reducing URS in high‐performance athletes
| Author and reference | Study design | Intervention | Impact on URS |
|---|---|---|---|
| Training modifications | |||
| Konig et al. 10 | Epidemiological questionnaire of 852 athletes attending for a medical check‐up | None | Lower training intensity was associated with reduced URS. Endurance training increases the risk |
| Tiollier et al. 23 | 21 military cadets undertaking 3 weeks of intensive training and 5‐day combat course | Reduced training load during the recovery period post intensive combat course | Lower incidence of URS in recovery period |
| Hellard et al. 16 | Prospective study of 28 national swimmers over 4 years | Changes in intensity and type of training | Incidence of URS increased with training load and resistance training |
| Putlur et al. 55 | Prospective study of 14 college soccer players over 9‐week season | None | Incidence of URS increased with training load |
| Fricker et al. 26 | Case study of elite swimmer with recurrent URS and immune suppression | Reduced training and stopped international competitions | Decreased incidence of URS at 1‐ and 3‐year follow‐ups |
| Therapeutic interventions | |||
| Schwellnus et al. 37 | 96 elite runners in a DBPCT assessed pre‐ and post 56 km marathon | Daily topical anti‐inflammatory nasal spray (fusafungine) intervention period not specified | Decreased incidence of URS |
| Cox et al. 38 | 45 well‐trained half‐marathon runners in a DBPCT | Daily topical anti‐inflammatory nasal spray (Difflam) for 1 week prior and 2 weeks post the race | Decreased severity of symptoms but not incidence of URS |
| Cox et al. 49 | 28 elite runners in a DBPCT with crossover arms | Anti‐herpes viral therapy (Valtrex) for 1 month in active arm | Eliminated EBV but did not reduce incidence of URS |
| Nutritional supplements | |||
| Kingsbury et al. 8 | 19 Olympic athletes with fatigue, inability to train and URTI and low glutamine levels | Increased protein intake for 3 weeks, resulting in increased glutamine levels | URS abated within 2 months, but fatigue persisted and reduced ability to undertake high‐intensity training |
| Scherr et al. 75 | 277 marathon runners in a DBPCT over 5 weeks | Non‐alcoholic beer containing polyphenols (anti‐oxidant, anti‐microbial and anti‐inflammatory properties) intake daily for 3 weeks prior and 2 weeks post a marathon | Reduced incidence of URS post marathon |
| Nieman et al. 76 | 20 trained male cyclists and 20 controls in DBPCT over 5 weeks of training and a 3‐day intense cycling period | Quercetin daily high dose for 3 weeks before, during and 2 weeks after a 3‐day period of intense cycling | Reduced incidence of URS in 2 weeks post the intensive training |
| Shing et al. 78 | 29 elite road cyclists in a DBPCT over 5 weeks of routine training followed by 5 days of intensive training | Bovine colostrum daily | Trend for reduced incidence of URS (P=0.08) |
| Crooks et al. 77 | 25 elite swimmers in a DBPCT over 10 weeks of routine training period before a national competition | Bovine colostrum daily | Trend for reduced incidence of URS (P=0.055) |
| Jones et al. 79 | 53 active males (not elite) in a DBPCT over 12 weeks | Bovine colostrum daily | Reduced incidence of URS and reduced salivary bacterial load |
| Clancy et al. 82 | 25 athletes in a DBPCT over 4 weeks | Probiotic (Lactobacillus acidophilus LAFT1‐L10 strain) daily | Reversal of defect in IFN‐ɣ secretion from T cells (viral control mechanism) |
| Cox et al. 83 | 20 male distance runners in a DBPCT over 16 weeks | Probiotic (Lactobacillus fermentum VRI‐003 strain) daily | Reduced incidence of URS and reduced severity of symptoms and trend for higher IFN‐ɣ secretion from T cells (P=0.07) |
| Gleeson et al. 81 | 84 endurance athletes in a DBPCT over 16 weeks | Probiotic (Lactobacillus casei Shirota strain) daily | Reduced incidence of URS |
| Lifestyle and environmental impacts | |||
| Konig et al. 10 | Retrospective questionnaire of 852 athletes attending for a medical check‐up | None | Coping with daily stress reduces incidence of URS Sleep deprivation increased the risk of URS |
| Hellard et al. 16 | Prospective study of 28 national swimmers over 4 years | None | URS incidence was higher in winter months |
| He et al. 71 | Prospective study of 225 endurance athletes over 16 weeks | None | URS incidence was higher in athletes with vitamin D deficiency |
Abbreviations: DBPCT, double‐blind placebo‐controlled trial; EBV, Epstein Barr virus; URS, upper respiratory symptoms.