Repetition speed

How fast should you perform your repetitions when you do your weight training?

Research seems to indicate that it is probably best to perform your reps in a slow, controlled manner, as this results in more tension on the muscle and less momentum (which reduces muscle tension).  Lifting faster allows you to lift more weight, but you end up using momentum and you create less stimulation to the target muscle group(s).  In addition, lifting faster will increase your chances of injury.

Research has compared 2 seconds up/4 seconds down with 10 seconds up/4 seconds down and has shown that for the average person, 10 seconds on the concentric phase resulted in more strength increase.(1)  We don’t know if 8 or 6 or even 4 seconds up would be equivalent, better, or worse.  For the average person, performing your reps in a slow, controlled manner is best, but I would not force yourself to do it superslow (10 seconds). For one thing, this form of training is very mentally taxing and boring.  For another thing, super slow will train your muscles to contract slowly, and this is not good for athletics, such as playing sports.

On the other hand, it is unwise and unsafe for the average person to fast or to use plyometrics (jumping down and up from a box, etc.).  This type of fast, explosive lifting should be reserved for serious, relatively young (16 to 30 year old) athletes.  It places too much load on the connective tissue in your joints.

REFERENCE:

 1. Wescott WL, Winett RA, Anderson ES, et al. Effects of regular and slow speed resistance training on muscle strength. J Sports Med Phys Fitness. 2001 June; 41(2):154-8.