Five types of strength: Delineate, test, and train
When training athletes for any sport, S&C coaches want to know 1) what is it we need to develop and 2) has our intervention successfully closed the gap we have identified.
In this article
At a glance
- Strength is not one quality — the literature describes 5 distinct domains.
- Each domain has its own tests, its own variables, and its own training modalities.
- Profiling athletes against these domains shows you exactly where the gap is.
- Paul Talty and Prof Paul Comfort get into the weeds of this in a live conversation — details at the end.
Gain a deeper understanding
Learn from Paul Comfort, Professor in S&C, and Paul Talty, experienced S&C coach, as they dissect strength and the implications for you as a coach.
When it comes to the development of strength many will consider it in the context of how much weight can be moved in a back squat or a bench press; but to narrow our perspective on strength to how much weight we can put on the bar in two simple exercises is to limit our understanding of what strength is.
Strength refers to the expression of force under a variety of conditions; and the tools we choose to employ for the training of strength will determine the outcome. Figure 1 is the classic graph from Rob Newton’s PhD (1997; itself adapted from the work of Häkkinen & Komi in the mid-80s) which illustrates the difference in adaptation of the force-time curve when training is focused on heavy resistance vs light resistance training.
Narrowing our perspective on strength to how much weight we can put on the bar in two simple exercises limits our understanding of what strength is.
Recent work by Mary Geneau (1), Lachlan James (2), and colleagues has sought to describe the distinct and different strength qualities that exist so that we can better understand the factors that may overlap versus the ones that are distinctly different which in turn will help us to bring more clarity to how we assess them and how we train them. This in turn can help practitioners to answer the questions set out at the start of this article.
Table 1 — Five-factor strength framework. Adapted from James et al. (2)
Maximal strength
Force expressed under maximal conditions
Isometric strength
The greatest amount of force applied to an unyielding object, regardless of the rate or ability to sustain the effort.
Heavy dynamic strength
A 1, 3, or 5 repetition maximum in common strength exercises.
Speed–strength
Force expressed under time-constrained conditions
Explosive strength
Early stage force production (0.030–0.150 seconds) as measured in an isometric task.
Fast dynamic strength
An expression of force produced maximally against no or little additional load over somewhat quick movement times (>0.30 seconds).
Reactive strength
The ability to produce force in a short/fast stretch-shortening cycle characterised by ground contact times <0.25 seconds.
0.030–0.150s
explosive strength
>0.30s
fast dynamic strength
<0.25s
reactive strength
Table 1 illustrates the five-factor strength framework set out by James et al. (2023). The first level of this framework describes strength in terms of the expression of force under maximal conditions (maximal strength) and force expressed under certain time-constrained conditions (speed-strength). These two umbrella terms cover the five factors which have been shown in the literature to be distinct forms of force expression and are described further in Table 1.
As practitioners, one of our jobs is to best understand the relative importance of each of these factors in the development of our athletes.
As practitioners, one of our jobs is to best understand the relative importance of each of these factors in the development of our athletes and to put in place training programmes that target their development. In many cases we will create a performance profile of our various athletes relative to some accepted standard or mean (e.g. the squad average) to identify areas where the athlete needs particular attention. Table 2 details common tests that can be used to assess these qualities and some of the variables that might be interrogated as part of that assessment.
Once you have access to this information it is possible to set out a training plan as per your own training philosophy or approach.
Once you have access to this information it is possible to set out a training plan as per your own training philosophy or approach. James et al. (2023) also provided a table detailing the primary and secondary training options for the development of each of these qualities and it is reproduced here in Table 3.
Recognising and understanding the difference between the various domains of strength and how they can be assessed and targeted can help to make our training prescription more streamlined, more targeted, and more effective. This foundation can help to make us better practitioners and it is this topic that I will be getting in to the weeds of some more in conversation with Professor Paul Comfort on September 3rd where I will be asking him for his expert perspective on what each of these domains of strength contribute to the delivery of performance outcomes on the pitch and how we can think about the development of each area in our training. Prof Comfort is known for his strong and sometimes controversial opinions on these topics so it is sure to be an engaging conversation so come and join us.
FAQs about this article
What are the different types of strength?
James et al. (2023) set out a five-factor strength framework. The first level describes strength in terms of the expression of force under maximal conditions (maximal strength) and force expressed under certain time-constrained conditions (speed-strength). These two umbrella terms cover five factors: isometric strength, heavy dynamic strength, explosive strength, fast dynamic strength, and reactive strength.
What is isometric strength?
The greatest amount of force applied to an unyielding object, regardless of the rate or ability to sustain the effort.
What is heavy dynamic strength?
A 1, 3, or 5 repetition maximum in common strength exercises.
What is explosive strength?
Early stage force production, between 0.030 and 0.150 seconds, as measured in an isometric task.
What is fast dynamic strength?
An expression of force produced maximally against no or little additional load, over somewhat quick movement times greater than 0.30 seconds.
What is reactive strength?
The ability to produce force in a short or fast stretch-shortening cycle, characterised by ground contact times under 0.25 seconds.
How is each strength quality tested?
Isometric strength: isometric squat or IMTP, using peak force. Heavy dynamic strength: 1RM or 3RM, using load lifted. Explosive strength: isometric squat or IMTP, using force at 0.100s or 0.150s. Fast dynamic strength: CMJ or SJ, using jump height, relative concentric impulse, and contraction time. Reactive strength: drop jump or 10-5 repeated jump test, using RSI, contact time, and jump height.
Why does distinguishing between strength qualities matter?
Narrowing our perspective on strength to how much weight we can put on the bar in two simple exercises limits our understanding of what strength is. Recognising and understanding the difference between the domains, and how they can be assessed and targeted, can help make training prescription more streamlined, more targeted, and more effective.
About the author
Paul Talty is the Associate Head of Performance Services (Physical) for Swim Ireland where he leads the S&C support for the National Centre (Dublin), the National Squads, and the National Teams. In addition to this, he assists in the management of other performance service support to athletes in the National Centres (Dublin and Limerick) and through the Sport Northern Ireland Sports Institute (SNISI). Over the last 10 years, Paul has delivered S&C support to a wide variety of sports and athletes including competitors at European, World, and Olympic levels while working at Coventry University and SNISI. Alongside his role at Swim Ireland, he is currently pursuing a Ph.D. investigating the mechanical determinants of change of direction performance in Gaelic football through the University of Salford.
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