Lighter Weights Can Still Make a Big Fitness Difference

     Studies show that lifting lighter weights can be just as effective has heavier weights in building muscle, in fact lighter weights reduce the risk of injury. Stuart Phillips, a professor of kinesthesiology at McMaster University in Ontario, says that resistance training is more important than cardiovascular exercise in maintaining muscle mass. Most people are under the impression that you need to lift 80 percent of your all-out maximum weight for 8 to 10 reps in order to build muscle. Phillips and his colleagues looked at what goes on inside muscles after conventional 80-percent-of-maximum lifting with few reps versus lifting 30 percent of maximum weight until the muscle becomes too fatigued to go on. This usually occurs after around 25 to 30 reps.They found that both methods produced the same amount of new protein. Another benefit of lighter lifting is that it is easier on joints, making it the best option for older people. This new information is controversial because contradicts the "rules"  already established by fitness experts.
     This article relates to the muscle and skeletal system. It shows how different types of exercise has different effects on the muscles and joints. Muscles grow in mass when you work out by creating more protein.
http://www.npr.org/blogs/health/2012/04/30/151710725/lighter-weights-can-still-make-a-big-fitness-difference