What is the ability of the muscles to perform movement over and over again for a long time?

We can define muscular endurance as the ability of a muscle, or a group of muscles, to repeatedly exert a force (contract) for an extended period.

This is a key fitness component and crucial for any endurance sport, and many team sports. In fact, any activity that involves repeated movements patterns involves muscular endurance. So, whether you’re an endurance or strength athlete, there will always be an element of muscle endurance involved.

Muscle endurance is also important for everyday health.

Why is it important?

Increasing your muscular endurance is essential for health, fitness, and sport.

• It makes everyday tasks easier—gardening, climbing the stairs, etc.

• Improves the effectiveness of fitness and strength workouts.

• Increases sports performance.

In a sporting context, this is important for sports that involve repeated movement patterns—such as running, cycling, swimming or even strength training. And is essential during prolonged endurance events, where it allows athletes to repeat thousands of muscle contractions without excessive fatigue.

Put simply, when you increase muscle endurance…

• Muscles can work harder before fatigue sets in.

• You can sustain a work rate for longer.

A running example

As an example, a runner completing a marathon in 2hrs 30—at a running cadence of 180spm—would perform over 13,000 muscle contractions per individual muscle (quadriceps, hamstring, gluteus maximus, etc).

A cycling example

One of the best examples is cycling time trials. With all factors being equal, success is determined by the cyclist who can sustain the most force (power) during the time trial.

Here, it’s not just about the number of muscle contractions—the force per muscle contraction is also critical.

As an example, if two cyclists can sustain a cadence of 90rpm (equivalent to 90 individual muscle contractions per minute); then the cyclist that generates more force per pedal stroke is producing more work per minute and will sustain a greater speed.

While aerobic fitness has a major effect; muscular endurance is also important and allows athletes to continue to sustain higher workloads before muscle fatigue compromises performance.

However, it’s not just important for individual sports…

Most team sports require muscular endurance.

It’s also essential for strength athletes.

Here, this allows a greater volume of strength training to be completed per set. And leads to a greater level of training adaptation.

When viewing this from a health perspective, it makes everyday tasks and activities easier.

What sports require muscular endurance?

As mentioned, this is important for any sport, or activity, that involves repeated movement patterns. It’s an essential component of many endurance sports including:

• Running,
• Cycling,
• Swimming,
• Triathlon and duathlon,
• Cross-country skiing,
• Rowing.

It also plays a vital role in many other individual sports (CrossFit, tennis, squash, boxing) and many team sports (football, hockey, netball and rugby).

What factors affect it?

Several factors affect muscular endurance including:

1. Muscle fibre types
2. Genetics
3. Endurance training
4. Strength Training

Muscle fibre types

The ratio of different muscle fibres can have a significant effect.

Slow twitch vs Fast Twitch muscle fibres

Our muscles contain two types of muscle fibres:

• Slow twitch (type 1)
• Fast twitch (type 2).

The percentage of each varies between individuals and also between muscle groups.

Slow twitch muscle fibres are very fatigue resistant. They contain large amounts of mitochondria and myoglobin, making them very efficient at generating energy through aerobic metabolism.

Fast twitch fibres are less fatigue resistant, but capable of producing more force per muscle contraction. We can divide fast twitch fibres into two distinct types:

Type IIa muscle fibres are more fatigue resistant than Type IIb. They are also more efficient at producing energy through aerobic metabolism, and show a greater level of adaptation to endurance training. In fact, they can become remarkably similar to slow-twitch fibers, following many years of training.

The proportion of each type varies between athletes.

Athletes with a greater proportion of the more fatigue resistant muscle fibres (Slow and Fast Twitch IIa) have a greater level of muscle endurance.

They also achieve greater levels of adaptation following endurance training.

Genetics

Genetics plays a role on several levels:

• First, genes determine factors such as the ratio of different muscle fibres.
• Second, they affect the adaptation to training—such as how we respond to endurance, strength, or power training.

One point to note: our genes never function in isolation—a combination of genetics and environment (training, nutrition, support, coaching etc) determine the level of strength, and endurance training adaptation.

Training for Improved Muscle Endurance

Training has a considerable effect—muscular endurance is one of the most trainable components of fitness.

So, what is muscle endurance training?… This is any exercise that results in improved muscular endurance.

Endurance Training

While we view endurance exercise as being about developing aerobic, or cardiovascular fitness; this is also necessary for improving the fatigue resistance of muscle fibres.

Through training we extend the fatigue resistance of muscles and muscle fibres—this should be a key focus for sports where aerobic metabolism is the principal energy source.

So, how can you use endurance training to develop muscular endurance?…

Use a range of intensities

By using range of training intensities–low, moderate, threshold, high-intensity and sprint intervals–you will increase the recruitment, and fatigue resistance, of slow and fast twitch muscle fibres.

• Prolonged easy/moderate exercise improves the muscular endurance of Type-I fibres. This increases, your ability to sustain work rates for prolonged periods. And is a key exercise intensity for all endurance sports, and is very important for long distance events like Marathons, Ultras and Iron distance triathlons.

• Tempo or lactate threshold training enhances the endurance of Type one muscle fibres, while also increasing the recruitment of Type-IIa fibres. This is important for developing the specific muscle endurance required for endurance events where the intensity is close to lactate threshold—10k and half marathon running, 40k cycling time trials, etc.

• High-intensity interval training increases muscular endurance at higher intensities. Which is a critical intensity for all endurance sports because this increases the recruitment of Type-I, IIa and IIb muscle fibres.

• Sprint intervals place greater emphasis on the fatigue resistance of type II fibres. They also benefit type I muscle fibres. This type of training increases the speed reserve, which makes exercising at slower speeds, and lower power outputs, easier and more sustainable.

Strength Training

Endurance athletes often overlook the benefits of strength training. However, this is proven to increase the fatigue resistance of both the slow and fast twitch muscle fibers.

So, why is strength training beneficial for endurance?… Muscle endurance is influenced by a combination of strength and endurance.

When you increase maximum strength, lower intensity exercise becomes easier and less fatiguing.

As an example, when you increase your maximum strength (1 repetition maximum) you can perform more repetitions at lower intensities, and maintain a higher work-rate for longer.

Another benefit is improved exercise efficiency.

Muscular Endurance Exercises for Sport

So, earlier we looked at endurance exercise—what about strength training? What strength exercises and approaches should you use?… This depends on the sport or training focus.

As an example, the approach used by a CrossFit athlete would be different to an ultra runner, or time trial cyclist.

Why exercise specificity matters…

The most important factor is to use exercises that are specific to your sport.

Here, you need to think about the muscles you will use, the movement patterns, and the intensity of exercise.

Things to consider:

• First, think about what are the primary muscles used when you exercise.

• Second, should you exercise a specific muscle in isolation? Or targeting a group of muscles.

As an example, a runner or cyclist might include the following exercises: calf raises, lunges, squats, deadlifts, resisted knee drives, side planks, front planks and glute bridges.

How many repetitions?

The number of repetitions, or exercise intensity, influences the level of adaptation. 

Endurance athletes often focus on higher repetition ranges—for example, 20-25reps (or higher). While this is effective, using heavier weights with fewer repetitions is also effective. In fact, completing sets of 10-15reps is very effective.

The advantage here is… this also improves muscle strength.

One point here: there are several types of strength and each contributes to exercise performance. For this reason, employing a range of intensities and repetition ranges is effective.

For example, if you strength train twice per week, then you could use a lower rep range during one workout (e.g. 10-15repetitions) and a higher repetition range during the second session (e.g. 20-25repetitions).

We can enhance strength training by making this sport specific.

• A good example would be a runner, completing hill running training. This is very sport specific since it develops strength and endurance while running.

• Another example could be a rower completing indoor rowing intervals at a high resistance level, or a swimmer using hand paddles. Again, these are very sports specific.

Exercise Tests for Muscle Endurance

Examples of muscle endurance tests include…

Lower body tests

Squats—perform as many squats as possible

Wall sit test—hold the squat position as long as possible.

Calf raises—complete as many calf raises as possible

Upper body tests

Push-up (or partial push-up) test—total number completed, or the amount in 60seconds

Pull-ups—complete as many pull-ups, or chin-ups as possible.

Abdominals/core tests

30, or 60 second, Sit-up test—complete as many sit-ups in the allocated time.

Plank hold—hold plank position as long as possible.

Side plank hold—hold side plank position as long as possible.

Isokinetic tests

These are useful for isolating specific muscle groups (quadriceps, hamstrings, etc.). And allow the assessment of muscle/strength endurance imbalances between muscles.

For example, they allow you to assess strength endurance imbalances between the left and right quadriceps, or hamstrings.

• Muscular endurance refers to the capacity of a muscle(s) to exert force for a prolonged time.
• This is required for most sports, and is critical for all endurance sports, many team sports, and is one of the components of fitness.
• It’s affected by several factors including muscle fibre types (slow and fast twitch muscle fibre proportions), endurance training, strength, genetics and trainability.
• Muscle endurance exercises include strength exercises (body weight, weights, resistance machines, resistance bands etc), sport specific exercises like hill running repeats, high-intensity intervals.
• Traditional strength training using lower repetition ranges (10-15reps) or higher repetition ranges (20-25 reps, or higher) are effective.
• Specific endurance training, allows an athlete to sustain a work rate for longer, and perform a greater amount of work in a given time.
• We can assess muscle endurance using specific tests.

References

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