The muscle bound myth

Ask anyone that has pulled a muscle and they will tell you the importance of flexibility. Flexibility can be defined as the ability to move a joint though it’s full range of motion.  Good flexibility is important for normal movement and injury prevention. Flexible hip and upper back joints help to maintain spinal alignment and proper posture to help minimize back pain.  Flexible ankles and shoulders help to reduce stress on the knee and neck region.  There is even evidence that inadequate flexibility may impair the ability to increase strength with resistance training.

When I began my personal adventure into weight training I was told that resistance training was going to decrease my flexibility and I needed to be careful of becoming “muscle bound”.  There is some scientific evidence to lead to his belief. A study done in 1995 out of University of Maryland, College Park and published in Medicine & Science in Sports & Exercise, tested 31 untrained men between the ages of 50 and 74 and found that, “the results indicate that the flexibility group increased its range of motion in shoulder abduction to a significantly greater extent than the strength training and flexibility group”. The “muscle bound” idea is also exacerbated by many young muscular males that have poor flexibility. This has all helped lead to the long held idea that weight training decreases flexibility.

However, is this really the case? In a recent study, Resistance Training vs. Static Stretching: Effects on Flexibility and Strength, published in the Journal of Strength and Conditioning Research found evidence that strength training can increase flexibility. After 5 weeks of either flexibility training or strength training, both groups increased their flexibility over the control group. Strength training increased flexibility instead of decreasing it.  The researchers stated that, “the results of the study suggest that resistance training – so long as it is done over that appropriate full range of motion – will has positive benefits on flexibility”. 

The problem isn’t with resistance training; it is with the inadequate range on motion most lifters have when preforming their resistance training exercises. Many recreational weight lifters tend to sacrifice range of motion for weight. Going too heavy and not going completely thorough the joints full range of motion. Same mistake may explain why the older adults in the first study didn’t increase their flexibility, they didn’t weight train through the full range of motion, as many untrained trainees seldom do. This is why proper form and a balanced weight training program are paramount. The best training option is to include both resistance training through a full range of motion and stretching to help improve and maintain flexibility.

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