European Federation of  Sports Medicine Assocciations

http://efsma.eu/

The American Physiological Society

http://www.the-aps.org/

JAMA Internal Medicine

http://jamanetwork.com/journals/jamainternalmedicine

The New England Journal of Medicine

http://www.nejm.org/

The American Heart Association

http://www.heart.org/HEARTORG/

The European Society of Cardiology

https://www.escardio.org/

American college of sports medicine

http://www.acsm.org/

British Journal of Sports Medicine

http://bjsm.bmj.com/