Plain language summary
Prolonged exercise, such as marathon running, is associated with upper respiratory tract (URT) symptoms and airway inflammation. Tart Montmorency cherry juice, high in phytochemicals such as anthocyanins and quercetin, has been shown to have anti-inflammatory and anti-oxidative properties and therefore may help reduce inflammation and oxidative stress triggered by exercise. In this pilot study, twenty marathon runners were randomly assigned to receive two servings a day of either a placebo drink or cherry juice for eight days ─ prior, during and after a marathon run. Any URT symptoms were reported, and inflammatory markers were measured pre- and post-race and 24 and 48 hrs after the race, from saliva (immunoglobulins and cortisol) and serum (C-reactive protein, CRP). No differences in the effect on immunoglobulins and cortisol were found between the two groups. The increase in CRP was significantly lower in the cherry juice group compared to the placebo group. 50% of the runners in the placebo group developed URT symptoms, while none were reported in the cherry juice group. The authors conclude that Montmorency cherry juice may protect the URT from inflammatory symptoms triggered by exercise. They propose further studies with larger sample size of participants, suffering from various inflammatory respiratory conditions.
Abstract
BACKGROUND Prolonged exercise, such as marathon running, has been associated with an increase in respiratory mucosal inflammation. The aim of this pilot study was to examine the effects of Montmorency cherry juice on markers of stress, immunity and inflammation following a Marathon. METHODS Twenty recreational Marathon runners consumed either cherry juice (CJ) or placebo (PL) before and after a Marathon race. Markers of mucosal immunity secretory immunoglobulin A (sIgA), immunoglobulin G (IgG), salivary cortisol, inflammation (CRP) and self-reported incidence and severity of upper respiratory tract symptoms (URTS) were measured before and following the race. RESULTS All variables except secretory IgA and IgG concentrations in saliva showed a significant time effect (P <0.01). Serum CRP showed a significant interaction and treatment effect (P < 0.01). The CRP increase at 24 and 48 h post-Marathon was lower (P < 0.01) in the CJ group compared to PL group. Mucosal immunity and salivary cortisol showed no interaction effect or treatment effect. The incidence and severity of URTS was significantly greater than baseline at 24 h and 48 h following the race in the PL group and was also greater than the CJ group (P < 0.05). No URTS were reported in the CJ group whereas 50 % of runners in the PL group reported URTS at 24 h and 48 h post-Marathon. CONCLUSIONS This is the first study that provides encouraging evidence of the potential role of Montmorency cherries in reducing the development of URTS post-Marathon possibly caused by exercise-induced hyperventilation trauma, and/or other infectious and non-infectious factors.
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