Obstacles to joining:
• obesity (body mass index, BMI, over 35)
• weight under 50 kg
• chronic diseases, for example diabetes
• continuous medication, with the exception of contraceptive pills
• heavy smoking (more than 20 cigarettes per day)
• low haemoglobin level (under 125 g/l for women, under 135 g/l for men)
• structural back problems, for example spinal disc herniation
• allergies with violent reactions, for example swelling of the pharynx
• use of intravenous drugs
• having had cancer