A group of 31 young females, tennis players and non-athletes, aged 16 +/- 2 years (range: 14 - 21 years), with a wide range of physical activity levels was used to investigate the relationship between total daily energy expenditure and the incidence of upper respiratory tract infection symptoms.
Methods: During a 12 week winter period, habitual daily activity (excluding training) was evaluated using a 3-day physical activity record. Tennis training was quantified using a validated method of estimating energy expenditure during play. Total daily energy expenditure was calculated from the sum of daily training plus mean habitual daily activity energy expenditures. The total group of subjects was divided in quartiles for total daily energy expenditure. A validated symptom checklist was used to assess the incidence and severity of upper respiratory tract infections, on a daily basis.
Results: The girls in the highest quartile of total daily energy expenditure (> or = 17,322 kJ/day) and in the lowest quartile (< or = 10,047 kJ/day) had the greatest incidence of URTI symptomatology, although the moderately active girls in quartile three (12,290 - 16,410 kJ/day) presented the lowest incidence. Significant differences in number of upper respiratory tract infection episodes, sickness days and symptomatology index were found between quartiles three and one (p < 0.05) and quartiles three and four (p < 0.01). Peak severity of symptoms was significantly lower in quartile three compared with all other quartiles (p < 0.05).