Serum but not exhaled breath condensate periostin level is increased in competitive athletes

INTRODUCTION Periostin is a matricellular protein expressed by many tissues. Its release may be enhanced, among others, through mechanical stimulation of muscles and bones as well as by cytokines of allergic inflammation. OBJECTIVES Our aim was to assess periostin levels in serum and exhaled breath condensate (EBC) of professional athletes, asthmatics and healthy controls. We also sought to determine whether acute treadmill exercise influences serum and EBC periostin. METHODS Study groups included 9 competitive swimmers, 10 mild-to-moderate asthmatics and 7 healthy controls. Athletes were assessed twice (in- and off-training period) while asthmatics and controls in one time-point. Data on demographics, allergy symptoms and exercise load were acquired through Allergy Questionnaire for Athletes (AQUA) and International Physical Activity Questionnaire (IPAQ). Serum and EBC were collected before and after treadmill exercise challenge. RESULTS Baseline serum periostin in swimmers during training period was significantly higher (5- to 7-fold) than in asthmatics (P = .01) and controls (P < .05). In EBC, lowest periostin levels were seen in athletes in-training as compared with off-training period (P < .01) and with asthmatics (P < .03). Acute bout of exercise did not induce significant changes neither in serum nor in EBC periostin in any group. CONCLUSION Increased serum, but not EBC, periostin levels in competitive athletes are probably because of permanently increased exercise load leading to stimulation, injury and regeneration of musculoskeletal tissues. Periostin may be considered marker of long-term exercise overload after confirmation in larger groups.