Performance-enhancing drugs

EPO -> naturally occuring hormone responsible for regulation of red blood cell production

• increase red blood cell count 
• performer able to carry/transport more oxygen 
• aerobic respiration more efficient/improved VO2 max
• Adverse side effects -> increased risk oh heart disease (blood more viscous -> greater strain on heart)
• common users -> cyclists 

Anabolic steroids - Testosterone 

• increase the synthesis of protein within muscle cells -> build-up of muscle tissue
• use of anabolic steroids -> decreases amount of fat in muscle and causes decline in brealdown rate of muscle-building proteins/speed up recovery time - allows heavier training regimes 
• Adverse side effects -> liver & kidney tumours/high blood pressure/increase in cholesterol/damages peripheral nerves in body/severe acne
• common users -> variety of power athletes

Human growth hormone (HGH) -> artificial growth hormone 

• enhances performance of explosive activities by increasing muscle mass and repairing bones, ligaments and tendons
• adverse side effects -> joint swelling + pain/high blood pressure/abnormal bone & cartilage growth/irregular heart rhythms/increased risk of diabetes
• common users -> shot-put/weightlifters

Beta blockers

• block action of adrenaline/noradrenaline
• reduce tension and calm performer
• cause arteries to widen, slow action of heart and decrease its force of contraction -> lowering blood pressure and reduced workload for heart
• adverse side effects -> tiredness/sleep disturbance/cold hands & feet
• common users -> archery/shooting