Time under contraction is not directly measured in a typical weight training program. Most people really don't even think about the number of seconds a given muscle is forced to work. Indirectly, ...

In most cases, you can exercise at full capacity if you only sometimes experience PVCs. You may need to reduce the intensity if you often experience PVCs or have an underlying heart condition.

Time under contraction is not directly measured in a typical weight training program. Matt Parrott, a freelance writer, is director of business development and population health solutions for Quest ...