 
 
 
1 
S3 Table. List of candidate factors (n=120). 
 
1. Training factors: 
Endurance capacity 
Maximal oxygen consumption 
Economy of movement (=energy utilization) 
Strength capacity 
Power capacity 
Speed capacity 
Lactate threshold 
Lung volume 
Heart volume 
Coordination capacity 
Flexibility capacity 
Agility capacity 
Reaction time 
Recovery speed 
  
2. Metabolism factors: 
Basal metabolism rate (=calories required to keep the body 
functioning at rest) 
Glycolysis capacity (=break down of glucose) 
Mitochondrial biogenesis (=growth of pre-existing mitochondria) 
Myoglobin storage capacity (=iron/ oxygen-binding protein) 
Thermogenesis (=production of heat in the body) 
Angiogenesis (=formation of new blood vessels) 
Fat metabolism (break down of fat for energy) 
Creatine kinase metabolism 
Lactate dehydrogenase metabolism 
Lactate buffering system (=regulation of lactate level) 
 
3. Body factors: 
Weight / BMI 
Total fat mass 
Regional fat mass 
Subcutaneous adipose tissue (=fat under the skin) 
Visceral adipose tissue (=fat around internal organs) 
Lean mass (=mass of all organs except body fat including bones, 
muscles, blood, skin) 
Bone mineral density 
Tendon stiffness  
Number of red blood cells (=erythrocytes) 
Muscle fibres - hypertrophy capacity (=muscle growth) 
Muscle fibres - type 1 vs. type 2a/b (=slow vs. fast twitch fibres) 
Muscle fibres - transformation capacity (type 1 vs. type 2) 
Muscle fibres - contraction velocity capacity 
 
 
2 
4. Hormone metabolism: 
Erythropoietin (EPO) level 
Insulin-like growth factor-1 (IGF-1) level 
Growth hormone level 
Cortisol level 
Epinephrine level 
Norepinephrine level 
Testosterone level 
Dihydrotestosterone level 
Oestradiol level 
Dehydroepiandrosterone level 
Ghrelin level 
Progesterone level 
Follicle-stimulating hormone level 
Gonadocorticoids level 
Human chorionic gonadotropin level 
Gonadotropin-releasing hormone level 
Thyroid hormones level 
Androstenedione level 
Anti-Müllerian hormone level 
 
5. Nutrition metabolism: 
Valine level 
Leucine level 
L-carnitine level 
Carnosine level 
Creatine level 
Carbohydrate metabolism 
Saturated fat metabolism 
Unsaturated fat metabolism 
Cholesterol level 
Omega 3 level 
Omega 6 level 
Vitamin deficiencies 
Vitamin A deficiency 
Beta carotene deficiency 
Vitamin B complex vitamins (B1-12) deficiency 
Vitamin C deficiency 
Vitamin D deficiency 
Vitamin E deficiency 
Vitamin K deficiency 
Folic acid deficiency 
Mineral deficiencies 
Iron deficiency 
Zinc deficiency 
Magnesium deficiency 
Selenium deficiency 
Gluten intolerance 
Lactose intolerance 
Caffeine metabolism 
Alcohol metabolism 
Antioxidant level 
 
3 
Bicarbonate level 
Cell hydration status 
Electrolyte balance/ hydration status 
Steroid metabolism 
 
6. Immune system: 
Detoxification process 
Cytokine responses 
Healing function of skeletal tissue 
Healing function of soft tissue 
Blood pressure regulation 
 
7. Injuries: 
Risk of left ventricular hypertrophy 
Risk of metabolic myopathy  
Risk of stress fractures 
Risk of upper respiratory tract infections  
Risk of non-functional overreaching  
Risk of joint injuries 
Risk of lumbar disk degeneration 
Risk of inguinal hernia 
 
8. Psychological factors:  
Stress resistance 
Motivation capacity 
Resilience capacity 
Concentration capacity 
Emotion regulation 
Pain sensitivity 
Aggression regulation 
Self-control 
Self-confidence 
Risk of eating disorders 
Risk of addiction 
Intro vs. extroverted personality 
Ability to differentiate 
 
9. Environmental factors: 
Smoking behaviour 
Alcohol usage 
Sleep quality 
Level of fatigue 
Heat resistance capacity 
Altitude training sensitivity 

Factors associated with high-level endurance performance: An expert consensus derived via the Delphi technique.
Konopka, Magdalena J,Zeegers, Maurice P,Solberg, Paul A,Delhaije, Louis,Meeusen, Romain,Ruigrok, Geert,Rietjens, Gerard,Sperlich, Billy