The purpose of this study was to examine the effects of a probiotic supplement during 4 mo of winter training in men and women engaged in endurance-based physical activities on incidence of upper respiratory-tract infections (URTIs) and immune markers. Eighty-four highly active individuals were randomized to probiotic (n = 42) or placebo (n = 42) groups and, under double-blind procedures, received probiotic (PRO: Lactobacillus casei Shirota [LcS]) or placebo (PLA) daily for 16 wk. Resting blood and saliva samples were collected at baseline and after 8 and 16 wk. Weekly training and illness logs were kept. Fifty-eight subjects completed the study (n = 32 PRO, n = 26 PLA). The proportion of subjects on PLA who experienced 1 or more weeks with URTI symptoms was 36% higher than those on PRO (PLA 0.90, PRO 0.66; p = .021). The number of URTI episodes was significantly higher (p < .01) in the PLA group (2.1 ± 1.2) than in the PRO group (1.2 ± 1.0). Severity and duration of symptoms were not significantly different between treatments. Saliva IgA concentration was higher on PRO than PLA, significant treatment effect F(1, 54) = 5.1, p = .03; this difference was not evident at baseline but was significant after 8 and 16 wk of supplementation. Regular ingestion of LcS appears to be beneficial in reducing the frequency of URTI in an athletic cohort, which may be related to better maintenance of saliva IgA levels during a winter period of training and competition.

The purpose of this study was to examine factors influencing susceptibility to upper respiratory tract infections (URTI) in 18-35-year-old men and women engaged in endurance-based physical activity during the winter months. Eighty individuals (46 males, 34 females) provided resting blood and saliva samples for determination of markers of systemic immunity. Weekly training and illness logs were kept for the following 4 months. Thirty subjects did not experience an URTI episode and 24 subjects experienced 3 or more weeks of URTI symptoms. These illness-prone subjects had higher training loads and had ∼2.5-fold higher interleukin (IL)-4 and IL-10 production by antigen-stimulated whole blood culture than the illness-free subjects. Illness-prone subjects also had significantly lower saliva S-IgA secretion rate and higher plasma IgM (but not IgA or IgG) concentration than the illness-free subjects. There were no differences in circulating numbers of leukocyte subtypes or lymphocyte subsets between the illness-prone and illness-free subjects. The production of IL-10 was positively correlated and the S-IgA secretion rate was negatively correlated with the number of weeks with infection symptoms. It is concluded that high IL-10 production in response to antigen challenge and low S-IgA secretion are risk factors for development of URTI in physically active individuals.

Caffeine is thought to act as a central stimulant and to have effects on physical, cognitive and psychomotor functioning. Purpose: To examine the effects of ingestion of a performance bar containing caffeine before and during cycling exercise on physical and cognitive performance. Methods: 24 well-trained cyclists consumed the products (performance bar containing 45 g carbohydrate and 100 mg caffeine (CAF), isocaloric non-caffeine performance bar (CHO), or 300 ml of placebo beverage (BEV)) at rest immediately prior to and performinged 2.5 h of exercise at 60%VO 2 max followed by a time to exhaustion trial (T2EX) at 75%VO 2 max. Additional products were taken after 55 and 115 min of exercise.Cognitive function measures (computerized Stroop and Rapid Visual Information Processing tests) were performed at rest before exercise and while cycling after 70 and 140 min of exercise and again 5 min after completing the after the T2EX ride. Results: Participants were significantly faster after CAF when compared with CHO on both the computerized complex information processing tests, particularly after 140 min and after the T2EX ride (P < 0.001).On the BEV trial, performance was significantly slower than after both other treatments (P < 0.0001). There were no speed-accuracy trade-offs (P > 0.10). T2EX was longer after CAF consumption compared with both CHO and BEV trials (P < 0.05) and T2EX was longer after CHO than after BEV (P < 0.05). No differences were found in the ratings of perceived exertionRPE, mean heart rate, and relative exercise intensity (%VO 2 max; P > 0.05). Conclusion:Caffeine in a performance bar can significantly improve endurance performance and complex cognitive ability during and after exercise. These effects may be salient for sports performance in which concentration plays a major role.

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The purpose of this study was to examine the effects of a probiotic supplement during 4 mo of spring training in men and women engaged in endurance-based physical activities on incidence of upper respiratory tract infections (URTI) and mucosal immune markers. Sixty-six highly active individuals were randomized to probiotic (n = 33) or placebo (n = 33) groups and, under double-blind procedures, received probiotic (PRO: Lactobacillus salivarius, 2 × 1010 bacterium colony-forming units) or placebo (PLA) daily for 16 wk. Resting blood and saliva samples were collected at baseline and after 8 and 16 wk. Weekly training and illness logs were kept. Fifty-four subjects completed the study (n = 27 PRO, n = 27 PLA). The proportion of subjects on PRO who experienced 1 or more wk with URTI symptoms was not different from that of those on PLA (PRO .58, PLA .59; p = .947). The number of URTI episodes was similar in the 2 groups (PRO 1.6 ± 0.3, PLA 1.4 ± 0.3; p = .710). Severity and duration of symptoms were not significantly different between treatments. Blood leukocyte, neutrophil, monocyte, and lymphocyte counts; saliva IgA; and lysozyme concentrations did not change over the course of the study and were not different on PRO compared with PLA. Regular ingestion of L. salivarius does not appear to be beneficial in reducing the frequency of URTI in an athletic cohort and does not affect blood leukocyte counts or levels of salivary antimicrobial proteins during a spring period of training and competition.

Citation: GLEESON, M. ... et al., 2013. Influence of training load on upper respiratory tract infection incidence and antigen-stimulated cytokine production. Scandinavian Journal of Medicine and Science in Sports, 23 (4) for the following 4 months. Comparisons were made between subjects (n=25) who reported 32 that they exercised 3-6 h/week (LOW), 7-10 h/week (MED) or ≥11 h/week (HIGH). The 33 HIGH and MED groups had more URTI episodes than the LOW group (2.4 ± 2.8 and 2.6 ± 34 2.2 vs 1.0 ± 1.6, respectively: P < 0.05). The HIGH group had ~3-fold higher IL-2, IL-4 and 35 IL-10 production (all P < 0.05) by antigen-stimulated whole blood culture than the LOW 36 group and the MED group had 2-fold higher IL-10 production than the LOW group (P < 37 0.05). Other immune variables were not influenced by training load. It is concluded that high 38 levels of physical activity are associated with increased risk of URTI and this may be related 39 to an elevated anti-inflammatory cytokine response to antigen challenge. 40 41

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