Muscular endurance is the application of repeated muscular force. Inflating a tire with a bicycle pump, walking up five flights of stairs, lifting a weight 20 times, and doing 50 sit ups are some examples of muscular endurance. It is developed by many repetitions against resistances that are considerably less than maximum. On the basis of limited data, significant muscle endurance may be developed in most people with a weight training program featuring 12 to 15 repetitions at 70% of maximum strength.A more systematic way to improve muscular endurance is to use a progressive resistance system similar to the one for strength development. You should select a weight for each exercise that you can lift 15 times (repetitions) but that you cannot lift 16 times. This weight becomes your 15 RM. You perform three sets, one each of 60%, 80%, and 100% of 15 RM. For example, if you can execute 15 repetitions of 80 lb for a particular exercise, you can proceed as follows – 
Isometric or static muscle endurance is the ability to sustain or hold a submaximum contraction for a period of time. Examples include the carrying of objects, such as groceries and other packages; pushing or pulling objects, such as a lawn mower; and carrying children.
There are important considerations in addition to the principles of training that should be applied to resistance training. First, the concentric and eccentric movement components of dynamic resistance exercises should be performed in a controlled manner. Second, breathe rhythmically and continuously while performing each repetition. Do not hold your breath while exercising because it produces an excessive rise in blood pressure. Third, if possible, exercise with a partner who can provide assistance and support in the form of spotting and by providing feedback, motivation, and companionship.