Many people desire a specific outcome from their workouts but unknowingly perform a workout that is contrary to their goals. For example, the marathon runner who wants to go the distance but packs on too much muscle to be light on his feet. If you've got goals but you aren't sure how to get there, understanding the difference between muscular strength and muscular endurance will help you devise the proper resistance-training plan.
Muscular endurance refers to the ability to perform a specific muscular action for a prolonged period of time. For example, your ability to run a marathon or to pump out 50 body weight squats is a product of good muscular endurance. You also use muscular endurance in your daily life when you rake leaves or walk up long flights of stairs.
Muscular strength is a muscle's capacity to exert brute force against resistance. Your ability to bench press a barbell weighing 200 lbs. for one repetition is a measure of your muscular strength. In daily life, you need muscular strength to pick up a heavy box.
Muscles are made up of different types of fibers called slow twitch -- or type 1 -- and fast twitch -- or type 2. Slow twitch fibers are responsible for endurance -- the ability to go long on a treadmill or cycle. Fast twitch fibers come in two types -- A and B. Type A are involved in both power and endurance -- for example, the ability to endure a long sprint or carry a heavy object across the room -- while type B are recruited for short, explosive moves, such as jumping or heaving a very heavy weight.
The proportion of muscle fiber types you have is largely determined by genetics. If you have a predomination of slow twitch fibers, you are better adapted to muscular endurance, able to perform long cardio sessions. A person with more fast-twitch fibers is more adept at muscular strength -- lifting heavy weights for a few repetitions or performing short bouts of high-intensity exercise.
Even though your genetics are predetermined, you can train to increase muscular strength or endurance. Endurance is trained by lifting lighter weights for a higher number of reps or running longer and longer distances. You can build strength by lifting heavier weights for fewer reps and doing short, powerful sprints. The range for building muscular endurance is typically 12 to 25 reps, and the range for building strength is one to eight.
Whether you emphasize strength or endurance training depends on your goals. Certain athletes, such as power lifters, football players and rugby players, need strength and bulk to perform their sports. Athletes such as tennis players, basketball players and martial artists are best served by focusing on both endurance and strength training -- specifically type A fast twitch fibers. They need power in short spurts to return a shot or sprint down a court. Endurance training is best for triathletes, distance runners and rowers.