At the most basic level, muscular strength can be defined as the ability of a muscle, or group of muscles to exert a force, or overcome resistance.
In reality strength is much more complex than this:
- It can be related to one single movement (maximum strength) or involved multiple repeated movements (strength endurance).
- There may also involve a speed component (power), or require a level of skill/coordination (agile strength)
- It may also be related to simple, single joint movements (hand grip strength, leg extension etc), or more complex multi-joint movements (squats, leg press or bench press).
In this article we take a look at some of the different types of strength. And consider their importance for endurance athletes.
What are the Different Types of Strength?
When it comes to strength there are a number of different types.
Firstly, there are three primary types of strength:
- Maximum – the greatest force that can be generated.
- Explosive – maximum force generated in minimum time.
- Muscular Endurance – force that can be exerted for sustained periods.
These are considered the key types of strength that relate directly to sports performance and are major components of fitness.
However, there are other types of strength that can also contribute to sports performance:
- Reactive – ability to use the elastic properties of tendons and muscles to quickly change from an eccentric to concentric contraction.
- Agile – ability to control and manoeuvre the application of force.
- Speed – moving at high speed with maximum load.
- Starting – ability to power a moment without momentum
Strength can also be described based on whether it’s general, specific or relative to bodyweight:
- Relative – ratio between max strength and body mass.
- General – strength of the whole muscular system.
- Specific – strength specific to a given activity or sport.
Finally, strength can also be related to the type of muscle contraction:
- Concentric – muscle shortens under tension
- Eccentric – muscle lengthens under tension
- Isometric – muscle neither lengthens or shortens when under tension.
Maximum strength refers to the greatest force that can be generated during one movement. This may involve single muscle groups, or joints, or may be more complex and involve multiple muscle groups and joints (squats, deadlifts etc).
Unlike with power or explosive strength, there is no speed or time component – this is purely about the weight that can be lifted, or force that can be generated, during one movement (repetition) irrespective of the speed of that movement. For this reason, it’s often referred to as “Low-Speed Strength” as the movement velocity is slow in comparison with High-Speed Strength (Explosive Strength).
The most common measure of maximum strength is the repetition maximum (1RM) – for example the maximum weight that can be bench pressed for 1 repetition.
Maximum strength plays a role in all sports, to a greater or lesser extent. For instance, it has much greater significance for strength athletes such as weightlifters, but less significance for endurance runners.
While maximum strength may not be a major component for endurance athletes; greater maximum strength gives you potential for increased work rate at submaximal intensities. Importantly, maximal strength training has been shown to benefit endurance athletes.
Maximum strength is sometimes referred to as strength base, as it sets a foundation of strength. This can then be built upon with other forms of strength training (power, strength endurance etc).
Explosive Strength / Power
In contrast to maximum strength, explosive strength refers to the ability to exert the maximum amount of force in the minimum amount of time.
In this way, it’s the product of:
- The amount of force that can be generated
- How quickly that force can be exerted
As such, it’s not just about the strength of the muscles but how efficiently they convert that force into movement. For this reason, it is often referred to as “High-Speed Strength”.
As you would expect, a number of factors come into play:
- The ability to quickly recruit and contract large numbers of muscle fibers
- Percentage of slow and fast twitch muscle fibers
- Co-ordination between muscle fibers and groups of muscles
- The use of elastic energy storage within muscles and tendons (reactive strength)
One point to note: an athlete with a high level of maximum strength won’t necessarily have a similarly high level of explosive strength. Equally, improvements in maximum strength don’t always equate with improvements in power, and vice versa.
Why is that?…As we’ve seen this is a combination of how much force a muscle can generate and how quickly that force can convert into movement – not just the total amount of force that can be exerted. As an example, an athlete with a high percentage of slow twitch muscle fibers will find it easier to develop maximum strength than develop power.
While developing explosive strength is more important for power athletes, it’s still beneficial for endurance athletes. In particular, developing power has been linked with improved efficiency in endurance athletes and especially in runners.
Muscular and Strength Endurance
While power relates to the speed at which force is generated, muscular or strength endurance refers to a muscles ability to continue to perform work for extended periods of time. In this way, it requires the ability to perform repeated movements, muscular contractions or multiple repetitions.
In contrast to power – which requires higher percentages of fast twitch muscle fibers – individuals with greater strength endurance tend to have much higher percentages of slow twitch muscle fibers.
It’s particularly important for sports that require repeated movements such as endurance running, cycling, triathlon, swimming, CrossFit and many team sports (basketball. football, hockey, rugby etc). However, it’s also important in any sport that involves multiple sets or repetitions during training, as it allows a larger volume and quality of these key training sessions.
In view of this, developing local muscular endurance is considered important for all endurance athletes.
So, that’s the main three types of strength, here’s some further types of strength…
Reactive strength refers to the ability to use the elastic properties of muscles and tendons. Put simply, reactive strength allows for an improved ability to make use of the .
It relates to the ability of muscles to quickly switch from an eccentric muscle contraction (where a muscle lengthens under tension) to a concentric muscle contraction (muscle shortens to exert a force). This process is known as the stretch-shortening cycle.
It’s affected by two primary mechanisms:
- The ability of muscles and tendons to store elastic energy during the stretch phase
- How quickly and efficiently that can be transferred to mechanical energy during the shortening phase.
Developing reactive strength is clearly important for sports involving fast explosive movements (sprints, jumps, throws etc). It’s also considered an important factor for improving the efficiency of endurance runners, where it can help to reduce ground contact times.
Agile strength refers to an ability to effectively control and manoeuvre the application of force. This can involve a change in the direction, speed or both. Traditional strength-based training typically involves controlled movements – both in terms of speed and direction. While, this is beneficial for strength development, often sport requires an ability to perform more complex or dynamic movements, which move through multiple planes of motion.
Developing agile strength is important for many sports including basketball, netball, rugby, CrossFit, gymnastics, and Strongman events. Not only can it improve exercise performance but it’s important for reducing injury risk.
While developing agile strength may not appear to be as important for endurance athletes, it’s an important training approach especially when looking to protect against increased injury risk. It may also help to enhance the benefits gained from strength training.
It’s also important for everyday activities such as moving or carrying objects.
Speed-strength refers to moving at a very high-speed with the maximum load possible. With speed strength the focus is on a fast movement speed. For this reason, resistance should not be too high so as to limit the speed of movement. Typically, speed strength training involves fast explosive movements, which are completed at a relatively low percentage of repetition maximum.
While Speed-strength is generally less beneficial for endurance athletes, it can prove to be beneficial when factored in during key training phases.
This refers to the ability of muscles to power a movement from a stationary start. Here, there is no momentum, or pre-stretch, to start the initial movement. Instead the athlete uses an isometric contraction to brace and create tension within the muscle and connective tissue. The athlete must then be able to rapidly power the movement using concentric muscular contractions.
While, important for sprint events, rugby scrums, shot put etc it has minimal benefit for endurance athletes. Perhaps, the one exception being time trial cyclists where start strength is required to power the initial acceleration from a stationary start position.
We can also view strength in relation to body mass (relative strength), and as general or specific strength…
This refers to the ratio between an athlete’s maximum strength and their body weight.
Strictly speaking, relative strength is not actually a specific type of strength but rather a way to measure, or interpret strength, in relation to an athletes body mass.
It’s expressed as the amount of force that can be generated per unit of bodyweight. In this way it can be viewed as a measure of your strength in proportion to body mass. As such it’s affected by factors such as changes in body mass and neuromuscular coordination.
It’s particularly important when considering athletic performance in sports such as cycling, running, boxing etc.
General strength refers to the strength of your whole muscular system. It’s a vital part of strength training and sets the foundation for an effective strength training programme. Not only is it important for long term progression but it also helps to reduce the overall risk of injury.
Developing general strength focuses on key exercises that work multiple muscle groups. Examples include squats, lunges, deadlifts, bench press, press-ups, pull-ups, bent over rows etc.
Developing general strength should be considered vital for all athletes.
Refers to the strength of the muscles, or group of muscles that will be used in a specific activity. In the context of sport this often referred to as “Sport Specific Strength”.
Importantly, this is developed after the development of general strength. When developing specific strength, the focus is on:
- Strengthening and conditioning the primary muscles used during a sporting activity.
- Using very similar movement patterns to the specific sport.
- Training in a way that develops sport specific strength.
With this in mind, the closer that you can recreate the movement patterns of your sport, the more effective the training will be. Examples of very specific strength training including hill running training and cycling hill repeats.
As with general strength, developing specific strength is vital for success in power, strength and endurance events.
Next, we look at strength in relation to the three types of muscle contraction – concentric, eccentric and isometric…
Concentric contractions occur when a muscle contracts (shortens) in order to exert a force.
- The pushing phase of push-ups, bench press and squats
- The pulling phase of pull-ups, bicep curls, and lat-pulldowns.
When we talk about concentric strength, we’re referring to the muscles ability to generate force during the shortening phase of a muscular contraction.
Importantly, the relative importance of concentric strength varies from sport to sport. For instance, concentric strength is more important for cyclists than runners.
In contrast to concentric strength, this occurs when a muscle lengthens while under tension. Put more simply, the muscle fibers contract while the muscle itself is lengthening.
Examples include the lowering phase of a pull-up, bicep curl or bench press. Another example is the quadricep muscles during downhill running. In this case, a percentage of the muscle fibers contract eccentrically in order to resist the forces of gravity and protect the knee joint from collapsing under that pressure.
- It’s known that eccentric muscle contractions can support greater resistance than concentric contractions.
- Interestingly, this occurs despite a significantly lower level of muscle fibre recruitment.
- As a consequence, eccentric contractions result in greater stress and damage to individual muscle fibers.
- Importantly, muscle fibers adapt very quickly to specific eccentric training. For these reasons, developing eccentric strength is an important part of successful strength training programs.
Isometric strength refers to a muscles ability to generates force without lengthening or shortening.
Examples include gripping an object, planks, or the core and torso muscles during press-ups, pull-ups and many other strength-based exercises. In this way developing isometric strength in core muscles can affect the effectiveness of strength training, improve performance and reduce overall injury risk.
As such, developing core strength and stability is an important part of any exercise training program.