Muscular endurance is the ability of muscle fibers to contract with a high level of force repeatedly. Muscular endurance training can improve your overall athletic performance by increasing your ability to sustain physical activity for longer periods of time.
Muscular endurance also helps in injury prevention. Muscular endurance workouts help to strengthen your muscles, tendons, and ligaments, which can help to prevent injuries during physical activity.
Muscular endurance is also sometimes known as strength endurance, a more intuitive term to understand it. Muscular endurance is your ability to utilize a high degree of strength for a long duration. This can also be understood in terms of power: Muscular endurance is the ability to generate a lot of power for a long time.
You may also want to read: What is Muscular Endurance? Why is it Important? How do you Train it?
This article explains how you can develop your muscular endurance through resistance training, muscular endurance benefits as it relates to your training, expand on muscle fibers, and how we can best leverage our physiology to create endurance performance.
WHAT IS MUSCULAR ENDURANCE?
Adaptations to resistance training, weight training, and developing muscular strength tend to exist on a continuum of repetitions and intensity. Repetitions, and the ability to continue lifting a weight or performing a bodyweight exercise, are based on the percentage of your one repetition maximum (1RM). 100% of your 1RM is the weight you could only lift once, and as that 100% decreases, you can perform more repetitions.
Neuromuscular adaptations to resistance training, and the firing of more muscle fibers as one, occur close to 100% of the 1RM. At the same time, muscular endurance will develop at a lower percentage of the 1RM with more repetitions.
Hypertrophy, or muscle growth, tends to develop between neuromuscular strength and endurance, but it should be noted is significantly more complicated and varies from person to person. This continuum is not an absolute guide to muscular development since there is heavy overlap between the types of resistance training, and they will support each other.
This being said, a common sense approach to training and SAID (specific adaptations to imposed demands) tells us that to lift something heavy, we need to practice lifting heavy things. To lift something many times, we need to practice lifting something for a long time. The SAID principle described above also further highlights the key difference between endurance exercises and muscular strength exercises.
Muscular endurance training needs to be separated from what is generally referred to as endurance training and should be approached from a resistance training perspective. Endurance training: running longer distances, cycling longer or faster, or preparing to climb multi-pitch routes are mostly metabolic in nature. This means that you should consider improving your energy pathways, aerobic and anaerobic capacity, ability to shuttle lactate, and cardiac output. Most of these adaptations occur at relatively low intensities. For example, developing your aerobic base and oxygen utilization happens at easy levels of effort.
Will muscular endurance for activities like running, climbing, and cycling develop without touching a weight? Absolutely, but it can only take you so far, and as you build your aerobic capacity, you start moving faster, which puts more stress on your body and increases your risk of injury. By moving weights that impose a demand on our muscles above our body weight, we can increase their capacity for longer and more significant amounts of work. This type of resistance training will then support and advance the hard-won increases in metabolic performance you’ve gained through building your aerobic base.
Remember that all resistance training exists on a spectrum of repetitions and intensity. If you have increased muscular endurance, it will not increase your ability to lift a heavier weight. It will support your ability to start lifting heavier weights for more reps but will not directly cause a significant increase in your 1RM. The rep ranges for endurance are generally too high, with too light of a weight, to build a lot of muscular strength.
HOW TO IMPROVE MUSCLE ENDURANCE?
Exercises for muscular endurance are based on the size principle, which holds that the number, type, and size of muscle fibers recruited for a specific action will be based on the demands of that action. Lifting a heavy tree off of the trail will require the full participation of all muscles involved. As you perform the lift, your body will send signals to your muscles that the smaller type I fibers won’t be enough, and larger type IIA and IIX fibers will also be needed. By contrast, swinging a trekking pole will not require the activation of more than your type I fibers because it is so light.
When building muscular endurance, we want to perform movements that primarily recruit the fibers we will use during our chosen activity. If you are a climber, then exercises that promote the repeated use of type I fibers in the biceps, wrists, shoulders, and back muscles (such as the pull-ups) will be best as long as they don’t require maximal muscle use.
MOUNTAINEERING TRAINING GROUP
Humans have three main types of muscle fibers: I (slow twitch muscle fibers), and IIA + IIX (fast twitch muscle fibers).
Type I fibers are highly fatigue resistant and have a high endurance level with a lower force output. They are found in postural muscles such as the lumbar, abdominals, and calf muscles. On the other hand, type II fibers fire faster and with more force and are less aerobic in nature.
While most people have a higher percentage of type IIA fibers, type IIX fibers are the fastest but will typically convert to type IIA under training load. It’s essential to note that every muscle has a mixture of these fiber types, and the percentage of fiber types is based on genetics and training. Slow-twitch fibers are essential for supporting muscular endurance activities, and they have a higher percentage of mitochondria, hemoglobin, and other infrastructure for using oxygen efficiently.
EXERCISES AND WORKOUTS FOR MUSCULAR ENDURANCE
Below is a list of exercises to improve muscular endurance. For each, your goal is between 15-75 repetitions, depending on how much weight you’re using or how difficult body weight feels. For example, a seasoned climber might see 25 pull-ups as very low effort and should either do more reps or add low weight. A road runner, however, might only be able to do 5 pull-ups but can knock out 75 bodyweight squats without breaking a sweat. Determining your load and rep schedule so these movements aren’t too easy is crucial to developing muscular endurance.
If using weights, then most muscular endurance workouts should be performed at approximately 50% of your 1RM. It is best practice to start with more complex exercises and finish with less complex ones. For example, step-ups, back squats, and Bulgarian split squats should happen right after your warm-up, and exercises like bicep curls, pull-ups, and bodyweight exercises should be performed toward the end of the workout.
Another workout structure used to promote muscular endurance is circuit training. Circuit training involves a larger list of exercises performed in quick succession for one or more sets. You do not linger on a single exercise, and it can be an excellent way to raise your heart rate and develop your aerobic base during resistance training. You can quickly accumulate muscle fatigue through circuit training, and a wide range of weights can be used. If you just realized that CrossFit is circuit training, you’re correct!
While most resistance training will be performed with concentric and eccentric motions (lifting a weight up and then lowering it down), isometric exercises can also develop muscular endurance. Isometric exercises involve no movement, the best example being the wall sit, in which the muscles produce force to hold your body or weight in a certain position.
The hang boards that climbers use to develop finger strength and wrist endurance are another example of using isometrics to create endurance. Isometric muscle contractions can generate enough force to prevent blood flow into the muscle, which can build up metabolites (such as lactate). “Bathing” the muscle in these metabolites can increase its ability to tolerate them at higher levels and increase endurance.
A two-legged exercise that allows for a high number of repetitions, and repeated bouts.
Single-leg exercises are more specific to mountain athletes and will develop a deeper endurance at few repetitions and will train important postural muscles like the glutes and calves.
Build postural strength and injury resistance with calf raises.
Build tricep, pectoral, and core endurance with push-ups though it’s more complicated to progress load with push-ups.
Pull-ups might not be an endurance movement for everyone, but they will be your bread and butter for building muscular endurance for climbing.
Last but not least, the almighty plank. Building through the many variations from 1-minute efforts to multiple minutes, or planking until failure, will positively affect your deep core endurance.
A classic two-legged isometric hold that can be easily added into a workout.
Weight Hill Climbs
An Uphill Athlete Classic. Similar to weighted step-ups in a gym, weighted backpack hill climbs are an excellent way to develop uphill endurance if you are a runner or mountaineer.
Other muscular endurance exercise examples include bicep curls with relatively low weight, bench dips, cable rows, and many other normal exercises that have been adjusted to match the resistance required to achieve muscular endurance.
CONSIDERATIONS FOR MUSCULAR ENDURANCE WORKOUTS
Proper form should be maintained throughout any exercise, especially as muscles start to burn towards the end of the set. If you can no longer maintain good form, that’s your signal to stop that set.
These are difficult workouts and require an appropriately long recovery time. Even if you are working at a relatively low intensity, muscle damage is still sustained. We typically program only one Muscular Endurance workout every 7-10 days with our coached athletes. Though pro-level athletes with perfect recovery practices can shorten these intervals to 3-4 days between workouts.