Variations in leptin and insulin levels within one swimming season in non-obese female cold water swimmers.

Aim: We examined whether cold water swimming for seven consecutive months changes basal leptin and insulin concentrations and insulin sensitivity in healthy non-obese women.

Materials And Methods: Fourteen recreational female swimmers aged 45 ± 8.7 years, regularly swimming outdoors during winter months were exposed to cold water at least twice a week. Fasting blood samples were collected in October, January and April. Serum leptin, insulin and glucose concentrations were tested and insulin sensitivity was calculated using updated model HOMA2.

Results: Repeated cold water baths significantly increased insulin sensitivity and decreased insulin and leptin concentrations (p = 0.006, p = 0.032, p = 0.042, respectively). Leptin concentration positively correlated with body-mass index (BMI) and insulin level (r = 0.412, r = 0.868, respectively). Insulin level inversely correlated with insulin sensitivity and positively with glucose (r = -0.893, r = 0.166, respectively). No associations between leptin and insulin sensitivity were found.

Conclusion: Regular cold water swimming may stimulate metabolic changes suggesting that leptin and insulin participate in adaptive metabolic mechanisms triggered by repeated cold exposure accompanied by mild exercise in healthy non-obese women.