Two components of muscle fitness assessment are muscle strength and muscle endurance. Adequate muscle strength and endurance are necessary for optimal health as well as athletic performance, increased lean mass, better aesthetics, and functional daily living. 

From a health perspective, adequate strength and endurance help us participate in activities of daily living without injury or undue fatigue.From a performance perspective, both are necessary for optimal performance in recreational sports and fitness activities.

Muscle endurance refers to the ability to exert a submaximal force consistently without fatigue over an extended period of time. Muscle strength is the ability of a muscle or muscle group to generate maximal force, or the greatest amount of force that can be produced in a single effort. This is also known as the 1-repetition maximum (1RM). Think of 1RM as the most weight you could move once. We don’t typically exercise at our 1RM, because it would be difficult to determine it for every muscle group. But this concept is very important to an Olympic power lifter, for example, who needs to be able to lift a very heavy load just one time in competition. We want to train to increase our overall strength and stamina, but will do this by estimating our 1RM, and then performing more than one repetition, such as 8 or 10 or even 12 repetitions for the benefits we are searching for, which include increased muscle strength and endurance, improved stamina, and increased muscle size.

The muscle fitness testing included here helps you determine your existing levels of strength and endurance so that you have an initial measure to gauge yourself against when you test again. You will be able to compare your initial testing results with those you achieve as you increase in muscle strength and endurance.

Strength and endurance are specific to the muscle group, speed of contraction, type of contraction, and joint angle being tested. Although muscle strength tests differ from muscle endurance tests, some component of muscle endurance can measure strength to a certain degree. This is important because it is difficult to safely, easily, and quickly determine true muscle strength in 1RM. 

But, knowing or at least having a good estimation of your 1RM is important for optimizing training.You want to perform your muscle endurance workouts at no less than 75 percent of your 1RM for optimal training benefits. Because getting a good estimate of your 1RM for every muscle group can be difficult, take a look at the sidebar Selecting Your Correct Weight Load for some recommendations.

Two muscle endurance tests that are easy to self-administer are the sit-up test and the push-up test. Both test muscle endurance relative to body weight. Another endurance test is the bench press test; because this test uses a standardised weight, the results do not vary as a function of body weight the way those of the sit-up and push-up tests do.