There is a big difference between Muscular Strength building exercise and Muscular Endurance building exercise.

"Muscular Strength - the ability of a muscle to exert force for a brief period of time. Upper-body strength, for example, can be measured by various weight-lifting exercises."

Weight lifting is a perfect example of this. Weight lifting is usually utilized to build strength. How much you can lift would be a measurement of it.

"Muscular Endurance - the ability of a muscle, or a group of muscles, to sustain repeated contractions or to continue applying force against a fixed object. Pushups are often used to test endurance of arm and shoulder muscles."

Sometimes pushups or situps are used to test muscular endurance. How many pushups or situps can you do without stopping? Sustained mountain biking, endurance-type cycling, paddling, rowing, climbing, hiking, running, jogging, walking, or even sustained weight lifting can be Muscular Endurance building exercise. The key is building your stamina and "to sustain repeated contractions or to continue applying force against a fixed object" for greater and greater lengths of time. Individual Muscular Strength building exercises usually do not last for more than a few minutes without a brief break.

Muscular Endurance building exercises do not have to have a cardiorespiratory element to them, although sometimes they do. In other words, when I run my heart rate approaches 200 beats per minute; and I tend to run longer and longer distances each week. This is an example of Muscular Endurance training done with Cardiorespiratory Endurance training. However, when I ride my bike, I still try to ride longer and longer distances (thus building my muscular endurance) but my heart rate stays very low (not building my cardiorepiratory endurance).

Hope that helps clear up the difference between the two.

J.