Problem description In industrialized countries there is a rapid increase in the number of senior citizens. In Austria more than 50% of the population is overweight, with highest prevalence in the age group from 60 to 74 yrs and the WHO lists physical inactivity as one of the main behavioral risk factors of cardiovascular diseases.

Especially in winter months, activity related energy expenditure was 40% and 31% lower in the US and Canada, respectively. In addition, in an Austrian study the winter season was associated with higher blood pressure, total cholesterol and body mass index, giving an increasing risk of chronic coronary disease by 6.8% in men and 3.6% in women.

Therefore, the development of intervention programs that overcome the winter physical activity deficit and be feasible also for elderly should be goal of future research. Alpine skiing (AS) and cross country skiing (XCS) have a long standing tradition in Austria and could potentially fill the winter physical activity gap. The Salzburg Skiing for the Elderly Study (SASES) has found AS to be a save and feasible possibility to improve the health of the aged population in many parameters. XCS as a competitive sport is already well explored but there are hardly any studies about its effects in the normal or elderly population. Unfortunately knowledge about the differences between AS and XCS in the physiological adaptation processes in the elderly population is also lacking.

Aims and hypotheses of the pre-study In order to standardize training interventions, the present pre-study aims at comparing physiological and metabolic parameters between AS, XCS and IT. Therefore, the results of the pre-study serve as determinants for the training parameters of the above mentioned main study.

We postulate that, based on the results of the present study, it is possible to set up comparable isocaloric training sessions for AS, XCS and IT for elderly and unfit persons.

Furthermore, we assume that elderly and unfit subjects are able to perform a full spectrum of intensities and techniques necessary to set appropriate stimuli for isocaloric comparison.

We hypothesize arterial stiffness indices and circulating microRNA (miRNA) patterns to change due to one bout of physical activity of AS, XCS, and IT with variations depending on the kind of sport.

Inclusion Criteria:

• written informed consent
• male or female
• age: 30+ years
• inconspicuous ECG
• Non-smoker for at least one year
• proper skills in alpine skiing and cross-country skiing

Exclusion Criteria:

• Participation in other clinical trials at the same time or within the previous 6 months
• Tiffeneau-Pinelli index: Forced Expiratory Volume in first second (FEV1) / Forced Vital Capacity (FVC) <60% with/without symptoms (coughing, sputum) or other evidence of a pulmonary disease
• medical condition which conflicts with participation in training
• Intake of anticoagulants
• Alcohol or drug abuse
• Severe obesity: BMI >40

Twenty healthy subjects (male=10/female=10) aged 30+ will be recruited.