Background and aim: The sympathetic nervous system may be involved in the pathophysiology of insulin resistance and metabolic cardiovascular syndrome in young men. The aim was to study the effects of long-term stress on different features of the metabolic syndrome (MES) in formerly non-obese healthy young males during 5 months of defined conditions.
Methods and results: Sixteen healthy male sailors (mean age 36.5 (SD)+/-7 years) participating in a sailing race around the world were recruited for the study. Investigations were done before the start and at stop overs after finishing laps 1, 2 and 4 (1, 2(1/2) and 5 months, respectively). Anthropometric and blood pressure data as well as biochemical data associated with MES were substantiated. Food intake and exercise were chartered and largely controlled. A mean weight loss of 4.5+/-2 kg (P<0.005), comprising both fat and lean body mass, was recorded during the first lap. Subsequently after 5 months, a weight gain, mainly consisting of 1.2+/-1.1 kg body fat (P<0.05), took place, concomitantly with a protein mass drop of 0.6+/-1.1 kg (P<0.05). The body fat gain accumulated on the abdominal region. Elevated blood levels of HbA1c, insulin and the triglycerides/high-density lipoprotein ratio were also observed during the race. Likewise heart rate and systolic blood pressure increased slightly but to a statistically significant extent.
Conclusions: Non-obese healthy young men exposed to long-term stress developed abdominal obesity and signs of a metabolic syndrome in embryo, also emphasized by biochemical and blood pressure alterations. It is suggested that long-term and sustained stress activation might be an additional risk factor for the development of MES, even after control of dietary and exercise habits.