Primary: To observe how hemodynamic parameters are affected by age during rest and exercise in healthy humans. Furthermore, how an acute fluid challenge changes hemodynamic parameters.

Secondary: To thoroughly examine this population with regard to cardiac performance and function, anthropometrics, metabolic status, exercise capability, constitution, pulmonary status, and humoral markers of organ functions. This population will serve as a healthy control group, to which different populations can be compared, hence the need for a comprehensive characterization.

Hypotheses:

Diastolic function and parameters associated with diastolic function gradually deteriorate with increasing age. The gradual deterioration is unmasked at an earlier age during exercise and fluid challenge, compared to measurements made at rest.

Inclusion Criteria:

• Age over 18 years
• No acute or chronic diseases that can influence hemodynamics
• Pause in medication with effect on hemodynamics 24h before experimental day
• Echocardiography, with no structural abnormalities with an impact on hemodynamics.
• ECG without any pathological findings, including arrhythmia
• Normal red and white blood count, normal renal, liver, thyroid, immune, and hematological function as well as normal electrolytes, HbA1c and natriuretic peptides
• Ability to perform graded bicycle exercise testing
• BMI in the range of 20-30 kg/m2
• Height within population mean ±2 standard deviations
• VO2-max within population mean ±2 standard deviations (age corrected)
• Acceptable sonographic conditions
• Informed consent

Exclusion Criteria:

• History of heart failure (verified or suspected), or heart failure verified by pathological left and right systolic and diastolic measurements of the heart
• Hypotension (systolic blood pressure < 100 mmHg)
• Inability to participate
• Pregnant women
• Diabetes