The Importance and Principles of Resistance Training

You have never heard a practitioner or coach state the following: “That player would be better if they were just a bit weaker.” But how do we develop our athlete’s strength and how strong is strong enough? Resistance training (RT) is training with an external resistance to increase strength (ability to exert force), anaerobic endurance, and / or muscle size (NSCA, 2016), and is considered a highly important modality to improve a variety of health and performance outcomes for the general population and sporting athletes (Kraemer and Nikita, 2021). In Part 1 of this blog, we will discuss the importance of resistance training and force production, and the key principles of training. And in part 2 we will discuss the 7-step process for designing RT programmes to improve your athlete’s strength and injury resilience.

Importance of Strength

Before designing a RT programme, it is central to understand the key terminology used in strength and conditioning (S&C), particularly strength and force, and the biomechanics and physiology which underpin these. Muscular strength is defined as “the ability to exert force on an external object or resistance” (Stone et al., 2016), while force is defined as “The pushing / pulling action that one object exerts on another” (Bartlett, 2007). Consequently, muscular strength and the ability to produce external forces is integral for human motion, based on Newton’s laws of motion (Figure 1).

A force applied to a body causes an acceleration of that body of a magnitude proportional to the force, in the direction of the force, and inversely proportional to the body’s mass. Thus, when a force applied is great enough to overcome a body’s inertia, acceleration will then occur. Overcoming the inertia of such objects requires a net external force greater than the inertia of the object. This is vitally important in sport as it forms the link between force and motion.In simplistic terms, the harder that we push or pull over a period of time (known as impulse), the greater the acceleration of the object (i.e., our own mass or external object) (Figure 2). For example, the more force, thus impulse, which is exerted into the ground during the propulsion phase of a vertical jump, the greater the take-off velocity and subsequently higher that we jump.

There is compelling evidence that stronger athletes display superior athletic performance across a range of tasks including sprinting, jumping, and changing direction, while improving strength directly enhances these tasks too. Additionally, engaging in RT and getting endurance athletes stronger can also improve exercise economy and time-trial performance, increasing factors such as stride length (runners) or power output (cyclists) at the same metabolic cost, while reducing overuse injuries and improving injury resilience (Beattie et al., 2014; Blagrove and Hooper, 2021).

Stronger athletes have also been shown to potentiate to a greater extent, tolerate greater training loads and volumes, and display greater fatigue resistance and recovery capacity (Suchomel et al., 2016; Johnston et al., 2014; Owen et al., 2015). Furthermore, consistently engaging in a well-designed RT programme can elicit positive tissue adaptations to bone, muscle, ligaments, and tendon, increasing their robustness to injury, with evidence demonstrating that stronger athletes are at a significantly decreased risk of injury (Lauersen et al., 2014; 2018; Malone et al., 2019). Thus, developing athletes’ strength capacity is vital for improving athletic performance, mitigating injury risk, and fatigue resistance.

Importance of Resistance Training and Aims

RT is training with an external resistance to increase strength (i.e., ability to exert force), anaerobic endurance, and / or muscle size (NSCA, 2016), and is associated with a plethora of positive health outcomes summarized in Figure 3. Consequently, irrespective of age, sex, and socioeconomic status, everyone should engage in some form of RT to improve health, function, and everyday life.

Programming relates to the selection of exercise variables to provide a training stimulus that elicits the desired adaptations (e.g., muscle hypertrophy, metabolic and neural alterations), and is not to be confused with periodisation (Cunanan et al., 2018).

Training is the process of preparing an athlete physically for the highest levels of performance.

Essentially the primary aim of S&C is to incorporate RT to elicit neuromuscular / mechanobiological / metabolic and musculoskeletal tissue adaptations to achieve the 3 primary goals: improved athletic performance, injury risk mitigation, and improved health. This is summarised in Figure 4. A well-designed training programme which conforms to the key principles of training and programming, which is coached effectively, can attain all 3 outcomes. A training programme which helps achieve the outcome can therefore be considered effective (i.e., functional); however, when designing a RT programme, it is critical to focus on the adaptation / goal we are trying to elicit, not the exercise. Therefore, to create an effective and safe training RT programme for the individual athlete, it must conform with the 7-step process associated with programming (to be discussed below).

The adaptations to RT can include, but are not limited to:

RT morphological adaptations:

• Muscle hypertrophy (increased muscle size and / or mass):
  • Increased contractile proteins
  • Increased number and size of myofibrils (increased diameter)
  • Increased size of fibres
  • Increased cross sectional area (type II:I)
  • Increased sarcomere density and changes: series / parallel
• Increased size and strength of ligaments and tendon
• Increased bone mineral density
• Fibre-type transition and increased muscle shortening velocity

RT neural adaptations:

• Increased motor unit recruitment and rate coding (rate of firing), synchronisation
• Increased muscle activation, intermuscular coordination, and intramuscular coordination
• Increase force / rate of force production
• Increased neural drive

RT biochemical factor adaptations:

• Increased testosterone, growth hormone, insulin like growth-factors, and catecholamines
• Minor increase in ATP and CP stores

RT Body composition adaptations:

• Increased fat free mass, reduced fat mass via increased metabolism (energy expenditure associated with EPOC (excess post oxygen consumption))

Muscle soreness associated with RT

• May develop as a result of RT because isolated muscle groups are being overloaded beyond normal use. Exercise induced muscle damage (EIMD) due to mechanical tension, muscular damage, and metabolic stress which are drivers for hypertrophy.

Acute-onset muscle Soreness

• Occurs during or immediately after the exercise and is usually caused by ischemia and the accumulation of metabolic waste in muscle. May last for 1 hour after exercise.

Delayed-Onset Muscle Soreness (DOMS)

• Occurs 24-72 hours after exercise
• Related to type of muscle contraction
• Eccentric muscle contraction produces a greater degree of DOMS

Although muscle damage, soreness, and fatigue are potentially created with resistance training, it is important to highlight that muscle damage and fatigue (stress) is necessary in order to adapt (supercompensate), with adequate doses and rest, to promote adaptations and increases in hypertrophy and strength. However, careful periodisation of stress / fatigue and manipulation of the fitness-fatigue model is the art of periodisation.

Types of RT Modalities

A variety of RT modalities are available to use to improve muscular hypertrophy, strength, and power, including: Machined-based training, Free-weight training, Cable machines, tubing, resistance bands, Calisthenics, Suspension (TRX), Medicine ball, and Kettlebell training.

Free-weight dynamic RT is considered the most effective modality for increasing strength, hypertrophy, and power, overall transfer to improved sporting performance (Stone et al., 2000). Specifically, compound multi-joint free weight exercises are more effective than isolation, single joint and machine-based exercises as a greater excess post oxygen consumption and endocrine response is elicited, the core stabilisation system is activated to a greater extent (i.e., stabilisers), and it is easier to target larger muscle areas (Stone et al., 2000). Although free weight RT can be initially technically challenging and requires more stability in multiple planes, with practice and good coaching, this mode of training results in superior strength gains and improved transfer to sporting performance and functional daily tasks compared to other RT modalities (NSCA, 2016; Stone et al., 2000).

RT Programming: Key Terminology and Principles of Training

Before designing an individualised RT programme, it is critical to understand key terminology related to training design which are commonly used in S&C (NSCA, 2016; Stone et al., 2016). Additionally, we will discuss the key principles of training (SPORT) to ensure that our periodised RT align with these principles.

Training

• The process of preparing an athlete physically, technically, tactically, psychologically, and theoretically rapidly for the highest levels of performance. Training involves more than simple growth and maturation and, of course, the highest levels of performance will be relative to the current status and genetic gifts of the athlete.

Volume

• Amount of work performed. Sets and repetitions of an exercise combine to make volume.

Intensity

• The difficulty of the work. Intensity is the amount of weight or resistance used in a particular exercise (%1RM).

Volume-Load

• The combination of volume and intensity. Volume-load is usually calculated as sets × repetitions × weight, or resistance used (kg). Determining the correct volume-load is central to provide a sufficient stimulus to allow supercompensation, but not too excessive to induce excessive fatigue, overtraining, or burnout (NSCA, 2016).

Frequency

• Number of training sessions expressed per day, per week, per month.

Specificity

When selecting exercises for the RT programme, they should conform to the principles of specificity and be relevant to the specific adaptations / outcomes / training stimulus we hope to achieve and elicit, and they must be relevant to the specific training goal (i.e., strength, power, hypertrophy) (Kraemer and Ratamess, 2004). In line with the principle of specific adaptation to imposed demands (SAID), the type of demand placed on the body dictates the type of adaptation that will occur. For example, if the aim is to develop lower-limb triple extensor strength (i.e., quadriceps femoris, gluteals, gastroc-soleus complex), a press-up will be considered an unsuitable exercise as this targets the upper limb (i.e., shoulder adductors, elbow extensors, and shoulder flexors). Instead, a back squat would be considered a more suitable exercise.

In simple terms, for training specificity, the more similar the training activity is to the actual sport movement, the greater the likelihood that there will be a positive transfer to that sport (to an extent, yes), and exercises can be specific with respect to the following (Kraemer and Ratemess, 2004):

1. Muscle actions involved
2. Speed of movement
3. Range of motion
4. Muscles groups involved

Siff and Verkoshansky (1993) have also provided an alternative term for training specificity and the transferability of training known as dynamic correspondence: “a generic term which refers to an exercise or training programme’s ability to directly affect the athletes sporting performance”. They suggest that training and exercises should conform to five similar criteria:

1. The amplitude (ROM) / direction of the movement: Do the joint movements, range of motion, & force-vector specificity resemble the sports skill?
2. The accentuated region of force production: Specificity of muscular effort and consequently force application throughout the course of a movement – ballistic? How do the joint angles when peak force is expressed compare?
3. The dynamics of effort: Force-velocity characteristics, contraction velocities. Does the exercise create overload?
4. The rate and time of maximum force production: Time similarities, typical contraction durations, rate of force production. Does the exercise replicate these demands?
5. The regime of muscular work: Type of muscular action: concentric, isometric, eccentric, stretch shortening cycle (SSC); bilateral/unilateral. Is force produced in a similar way?

Exercises do not necessarily have to achieve all of the above-mentioned criteria because this will be dependent on the specific adaptation, we are trying to elicit relevant to the individual’s training goal. This is okay as it is very difficult for one exercise to meet all the above criteria. But we must be aware of the sport-specific trap (i.e., just copying the sports movement with a resistance band or weighted vest). If it was just that easy, athletes would only practice the sport itself. However, in general, for sporting transfer, biomechanically similar tasks are selected. Thus, a good understanding of kinesiology and motion analysis is required. For example, if the aim is to improve vertical jumping abilities, a high-load dynamic back squat conforms to training specificity and dynamic correspondence with respect to muscle actions, muscle groups, direction of motion, dynamics of effort, and regime of muscular work (Figure 5). To make this exercise even more specific, we can make this a ballistic exercise by reducing load and coaching the athlete to accelerate and jump off the floor. This will result in more similar contraction durations, velocities and regimes of muscular work.

Progressive overload

Refers to the gradual increase of stress placed upon the body, by continually exposing the individual to a stimulus that it is not accustomed to adapt (Kraemer and Ratamess, 2004). This can be achieved the following ways in a RT programme:

• Increased load (kg)
• Increased repetitions
• Change duration / speed of movement
• Change rest period
• Increase / change sets or training frequency
• Increased training volume-load (sets × reps × load)

Reversibility

When a training stimulus is taken away from an athlete for an extended period of time, they will not be able to maintain a certain level of performance. Over time, the gains that were achieved will return to the original level which is known as detraining (NSCA, 2016; Suchomel and Comfort, 2018). And some example decay rates / residual training effects (i.e., how long the quality can be maintained for upon cessation of training stimulus) for key physical and fitness qualities are provided in Table 1 (Issurin, 2008). For example, when an athlete takes the summer off from training, they can expect to become detrained. Thus, a strength training stimulus is paramount all year round.

Variation / Tedium

Alterations in one or more of the programme variables to allow for the training stimulus be optimal which helps prevent staleness and boredom (Kraemer and Ratamess, 2004). Over the course of the programme, you may change / vary:

• Training volume (sets, reps, frequency) (low, moderate, high)
• Training intensity (%1RM) (low, moderate, high)
• Exercise selection / modality

We cannot expect the athlete to do the same thing all the time, thus creating variation is the foundation of periodisation; to optimise performance, manage fatigue, and mitigate injury risk.

Summary

In this blog, we have highlighted the importance of developing strength for athletes via RT, with a plethora of potentially positive adaptations that can be elicited. Before designing a resistance training programme (which will we discuss in part 2), it is highly important to understand the key principles of training (SPORT): Specificity, Progressive overload, Reversibility, and Tedium. However, we introduce a final forgotten training principle as suggested by Cleather (2018): CONSITENCY in training. We can have the best designed programme in the world, but this is redundant if our athlete does not consistently engage with the programme.

Key recommended reading:

Sheppard, J. M., & Triplett, N. T. (2016). Program design for resistance training. Essentials of Strength Training and Conditioning, 4th ed.; Haff, GG, Triplett, NT, Eds, 439-470.

Kraemer, W. J., & Nitka, M. (2021). Variables in Designing a Workout. Strength & Conditioning Journal, 43(3), 127-128.

Suchomel, T. J., & Comfort, P. (2018). Developing muscular strength and power. Advanced Strength and Conditioning-An Evidence-based Approach, 13-38.

Suchomel, T. J., Nimphius, S., & Stone, M. H. (2016). The importance of muscular strength in athletic performance. Sports medicine, 46(10), 1419-1449.

References

Bartlett, R. (2007). Introduction to sports biomechanics: Analysing human movement patterns. Routledge.

Beattie, K., Kenny, I. C., Lyons, M., & Carson, B. P. (2014). The effect of strength training on performance in endurance athletes. Sports Medicine, 44(6), 845-865.

Blagrove, R. C., & Hooper, D. R. (2021). Strength Training for Enhancing Performance and Reducing Injury Risk. In The Science and Practice of Middle and Long Distance Running (pp. 207-222). Routledge.

Cleather, D. J. (2018). The little black book of training wisdom. Dan Cleather.

Issurin, V. (2008). Block periodization: Breakthrough in sports training. New York, NY: Ultimate Athlete Concepts.

Johnston, R. D., Gabbett, T. J., Jenkins, D. G., & Hulin, B. T. (2015). Influence of physical qualities on post-match fatigue in rugby league players. Journal of Science and Medicine in Sport, 18(2), 209-213.

Kraemer, W. J., & Ratamess, N. A. (2004). Fundamentals of resistance training: progression and exercise prescription. Medicine & science in sports & exercise, 36(4), 674-688.

Lauersen, J. B., Andersen, T. E., & Andersen, L. B. (2018). Strength training as superior, dose-dependent and safe prevention of acute and overuse sports injuries: a systematic review, qualitative analysis and meta-analysis. British journal of sports medicine, 52(24), 1557-1563.

Lauersen, J. B., Bertelsen, D. M., & Andersen, L. B. (2014). The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials. British journal of sports medicine, 48(11), 871-877.

Malone, S., Hughes, B., Doran, D. A., Collins, K., & Gabbett, T. J. (2019). Can the workload–injury relationship be moderated by improved strength, speed and repeated-sprint qualities?. Journal of science and medicine in sport, 22(1), 29-34.

Owen, A., Dunlop, G., Rouissi, M., Chtara, M., Paul, D., Zouhal, H., & Wong, D. P. (2015). The relationship between lower-limb strength and match-related muscle damage in elite level professional European soccer players. Journal of sports sciences, 33(20), 2100-2105.

Siff, M. C., & Verkhoshansky, Y. V. Supertraining: Special Strength Training for Sporting Excellence (1993) Johannesburgo. University of Witwatersrand, 60-61.

Stone, M. H., Collins, D., Plisk, S., Haff, G., & Stone, M. E. (2000). Training principles: Evaluation of modes and methods of resistance training. Strength & Conditioning Journal, 22(3), 65.

Stone, M. H., Cormie, P., Lamont, H., & Stone, M. (2016). Developing strength and power. Strength and conditioning for sports performance, 230-260.

Suchomel, T. J., & Comfort, P. (2018). Developing muscular strength and power. Advanced Strength and Conditioning-An Evidence-based Approach, 13-38.