Physical activity triggers complex molecular responses, including changes in immune-, stress-, and metabolic pathways. For example, autophagy is essential for energy and cellular homeostasis through protein catabolism, and dysregulation results in compromised proteostasis, reduced exercise performance, and excessive secretion of signaling molecules and inflammatory proteins. However, previous research has been limited by the extend of molecules measured and biological processes covered. A better understanding of these processes through multi-omic analysis can improve knowledge of molecular changes in response to exercise. The main purpose of the investigators study is to analyze the effects of acute exercise in correlation to autophagy and other signaling cascades. Specifically, the investigators plan to perform multi-level molecular profiling in a cohort of healthy male elite cyclists and male and female recreational athletes, before, during, and after a bicycle ergometer test. The results will be compared to a control cohort without intervention.

This is a non-randomized controlled trial performed at the Paracelsus Medical University, Salzburg, Austria. The study will recruit 80 healthy men and women. Subjects who meet the inclusion criteria will be allocated to four arms (n = 20 in all groups): 1. elite cyclists, 2. male recreational athletes, 3. female recreational athletes, 4. male control group.

After overnight fasting and medical check-up, groups 1-3 will undergo a bicycle ergometer-based exercise protocol designed to span low (aerobic) to severe (anaerobic) domains of exercise. The protocol consists of a 15 min aerobic warm-up phase followed by a ramp-bicycle ergometer protocol.

During exercise, performance-relevant data will be continuously monitored. Venous blood specimens will be collected before exercise (baseline), at the end of the warm-up as well as 2 min, 10 min, and 30 min in recovery.

Inclusion Criteria:

• All arms: ability to give written informed consent
• Arms 1- 3: inconspicuous medical examination (medical history, resting ECG, echocardiography)
• Elite athletes (arm1, cyclists): maximum oxygen uptake > 65 ml/kg/KG
• Elite athletes (arm1, cyclists): participation in cycling competitions on a regular basis
• Recreational athletes (arms 2 and 3): maximum oxygen uptake < 65 ml/kg/KG for male subjects and < 55 ml/kg/KG for female subjects

Exclusion Criteria:

• All arms: unable to communicate adequately by language
• All arms: regular use of prescription drugs other than thyroxine or antihistamines
• All arms: alcohol consumption as equivalent doses averaging more than 40 g of pure alcohol per day
• All arms: use of illicit drugs
• All arms: known diseases of the cardiovascular system
• All arms: arterial hypertension over 160/90 mmHg at rest
• All arms: known pulmonary diseases, especially bronchial asthma
• All arms: surgery less than 4-6 months ago.
• All arms: abnormalities in the medical examination (medical history, resting ECG, echocardiography)
• Arms 1-3: orthopaedic diseases that preclude maximum exercise on a bicycle ergometer
• Elite athletes (arm1, cyclists): maximum oxygen uptake < 65 ml/kg/KG
• Recreational athletes (arms 2 and 3): maximum oxygen uptake > 65 ml/kg/KG for male subjects and > 55 ml/kg/KG for female subjects
• Arm 3: positive urine ß-HCG