Muscular Endurance

What is Muscular Endurance?

Muscular endurance can be defined as the ability of a muscle, or a group of muscles, to repeatedly exert a force for an extended period of time.

Not surprisingly, it’s a key component of success in any endurance sport and many team sports. In fact, any activity that involves repeated movements patterns, requires muscular endurance. So, whether you’re an endurance, or strength athlete, there will always be an element of muscle endurance involved.

It’s also important for everyday health and is considered one of the key components of fitness.

Why is muscular endurance important?

Put simply, it allows your muscles to work harder for longer periods of time. So, if your muscles need to contract multiple times – such as when running, cycling, swimming or even strength training – then you need muscular endurance.

It’s particularly important during prolonged endurance events, where it allows athletes to repeat a series of muscular contractions without excessive fatigue. Not surprisingly, this is essential for success in many endurance sports, allowing athletes to outperform their competitors.

Perhaps, one of the best examples is cycling time trials. In this case, success is often determined by the cyclist who can sustain the most force (power) during the time trial. However, it’s not just important for individual sports and often makes a difference in team sports as well.

It’s also important for strength athletes, where it allows a higher volume of strength training to be completed per set. In turn this leads to a greater level of training adaptation.

When viewing this from a health perspective it’s also important for completing everyday tasks and activities.

So, what sports require muscular endurance?

As mentioned, it’s important in any sport, or activity, where there are repeated movement patterns. In this way, it’s particularly important for endurance events 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) as well as many team sports (football, hockey, netball and rugby).

What factors affect it?

A number of factors affect muscular endurance including:

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

Muscle fibre types

The percentage of different muscle fibre types can have a significant effect.

Slow twitch vs Fast Twitch muscle fibres

Our muscles are made up of two different types of muscle fibres:

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

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

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

On the other hand, fast twitch muscle fibres are less fatigue resistant, but capable of producing more force per muscle contraction. Fast twitch muscle fibres can also be divided into two distinct types:

  • Type-IIa
  • Type-IIb

Essentially, Type IIa muscle fibres are more fatigue resistant than Type IIb. They are also more efficient at producing energy aerobically than Type-IIb. Interestingly, they also show a greater level of adaptation to endurance training. In fact, Type-IIa muscles can become very similar to slow twitch muscle fibres after many years of training.

The percentage of each muscle fibres varies between different athletes. Not surprisingly, athletes with a greater percentage of the more fatigue resistant muscle fibres (Slow Twitch and Fast Twitch IIa) tend to have a greater level of muscle endurance. In addition, they respond more effectively to endurance training.

Genetics

Genetics clearly plays a role on a number of levels:

  • Firstly, our genes determine factors such as the percentages of different muscle fibre types.
  • Secondly, and of equal importance, our genes affect how well we adapt to different types of training. In particular, our genes can determine how well we adapt to either endurance or strength training. 

One point to note: it’s important to remember that our genes never work in isolation – it’s a combination of your genetics and environment (training, nutrition, support, coaching etc) that determines long term success.

Training for improved Muscular Endurance

Not surprisingly, training can have a significant effect. In fact, it’s one of the most trainable components of fitness.

So, what is muscle endurance training? Essentially, it’s any training that can lead to improvements in muscular endurance.

In this sense it can involve:

Endurance Training

Whilst, we often view endurance training as more about developing aerobic, or cardiovascular fitness, it’s also an important method for improving the fatigue resistance of muscle fibres. In fact, endurance training is a key factor in developing the endurance of muscles and muscle fibres, and especially for any sport where aerobic metabolism is the primary energy source.

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

A key factor here, is to include a range of training intensities to increase the recruitment, and fatigue resistance, of slow and fast twitch muscle fibres. In this way, it’s important to include low, moderate, threshold and high intensity endurance training.

  • Prolonged easy/moderate training to specifically improve muscular endurance of Type-I fibres. This helps to improve your ability to sustain work rate for prolonged periods. It’s a key training intensity for all endurance sports, but particularly important for long endurance events like Marathons.
  • Tempo or lactate threshold training can help to improve the endurance of Type one muscle fibres, whilst also increasing the recruitment of Type-IIa muscle fibres. This is important for improving 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 improves muscular endurance at higher intensities. It’s an important training intensity for all endurance sports as it increases the recruitment of Type-I, IIa and IIb muscle fibres.

Strength Training: The Importance of Muscle Strength

Strength training is often overlooked by endurance athletes, but it can be particularly effective for improving the fatigue resistance of both the slow and fast twitch muscle fibres.

So, why is improving strength beneficial for endurance?…(well), muscle endurance is affected by both your strength and endurance. And when you increase your strength, you also lift your muscle endurance, which makes exercising at lower intensities feel easier and less fatiguing. In this way, when you increase your maximum strength you will be able to complete more repetitions at lower intensities, or maintain a higher work-rate for longer.

Another benefit is improved exercise efficiency.

Muscular endurance exercises for sport

So, earlier we looked at endurance training, what about strength exercises? What strength exercises and approaches should you use?

This depends a lot on the sport or training focus. As an example, the approach used by a CrossFit athlete would be very different to an ultra runner, or time trial cyclist.

The importance of exercise specificity

The most important factor is to use exercises that are specific to your sport. In this way, you need to think about the muscles you will be using as well as the intensity of exercise.

Things to consider:

  • Firstly, think about what muscles require muscular endurance when you compete.
  • Should you be working 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, has an effect on the level of adaptation. 

Often, endurance athletes focus on higher repetition ranges – for example 20-25reps, or even higher.

While this is an effective approach, using slightly heavier weights with a lower repetition range is also effective.

In fact, completing sets of 10-15reps can be highly effective. The advantage here, is that it also improves muscle strength.

Using a range of different intensities and repetition ranges can be particularly effective. For example, if you’re strength training twice per week, then you could use a lower rep range during one session (e.g. 10-15repetitions) and a higher repetition range during the second session (e.g. 20-25repetitions).

Strength training can be further improved by making it highly sport specific. A good example would be a runner, completing hill running training to develop sport specific strength and endurance. Another example could be a rower completing indoor rowing intervals at a high resistance level, or a swimmer using hand paddles.

Summary

  • Muscle endurance refers to the ability to exert force for an extended period of time.
  • It’s required for most sports to varying extents, but is particularly important for all endurance sports and many team sports.
  • It’s influenced by a number of factors including muscle fibre types (slow and fast twitch muscle fibre percentages), 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 repetitions, high intensity intervals.
  • Traditional strength training using both normal repetition ranges (10-15reps) or higher repetition ranges (20-25 reps, or more) are effective.
  • Following endurance training an athlete is able to complete more work over a given amount of time. This is key for success in all endurance events.

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