Background: The serum concentration of creatine kinase (CK) is used widely as an index of skeletal muscle fibre damage in sport and exercise. Since athletes have higher CK values than non-athletes, ...

Beth Skwarecki is Lifehacker’s Senior Health Editor, and holds certifications as a personal trainer and weightlifting coach. She has been writing about health for over 10 years. Almost every gym I’ve ...

In the world of high-performance fitness, most people waste hours arguing about "fat-burning zones" while completely ignoring the only metric that truly removes body fat: total energy expenditure over ...

If you follow the run/walk method, you know alternating run and walk intervals can save energy and ultimately improve your overall pace. And if you progress those run/walk intervals the right way, you ...

Q: I got into a discussion the other day about the lenght of intervals. This program has as you know one interval of 30 seconds and one of 1 minute (I am just finishing week 2 and those have been the ...