Most literature defines strength as the ability to produce force by muscular contraction. Newton’s first law of motion states that an object will remain at rest unless a force is placed upon it. For instance, my cup of tea will not move unless I push against it. This law refers to inertia, which is essentially an object’s reluctance to move.
Newton’s second law of motion, referring to the acceleration of an object, states that force is a product of mass (kg) and acceleration (meter/second). Finally, Newton’s third law states: “For every action, there is an equal reaction.” For this, imagine a baseball player or cricketer catching a ball. Unless they want their teeth caved in, they apply a force against the ball to prevent any further negative work.
Now, imagine this principle during the bench press. To overcome the gravity of a significant mass, we apply a greater quantity of force to the barbell. This is an example of positive work. Recently, a golf coach highlighted the importance of the third law in his sport during a conversation. In theory, if a golfer can apply more force against the floor, the clubhead velocity that they can generate should be greater. With more velocity, as well as other technicalities, the ball should travel further.
Verkhoshansky and Siff refer to strength as having two divisions: structural and functional.1 Structural training is the process of affecting the musculature itself, such as an increase in actin and myosin filaments as a result of heavy strength training. Generally, structural training serves the purpose of inducing hypertrophy, whether it is myofibrillar, where an increase in the density of fibers is evident, or sarcoplasmic, where cellular cytoplasm increases. Functional adaptations are the products of training that are then expressed during sports performance: for instance, strength-speed. While it may seem obvious that understanding the purpose of training is imperative before programming, there is a distinct difference between the two in terms of the variables of load, sets, reps, rest, and variation.
Fortunately, and certainly more recently, coaches and parents alike have “succumbed” to the premise that physical ability is not the sole contributor to performance. It is the most likely to change the outcome on the field, court, or track, or in the pool but, without addressing the more holistic elements, there is a chance that athletes work at 70%. Coaches are mainly full-time strength and conditioning practitioners, but also part-time (bordering on full-time) life coaches.
Types of Strength
There is more to strength than what we see when a powerlifter grinds a 475-pound deadlift. That would be a case of absolute strength, which is the maximum amount of tension and force applied to an object, irrespective of mass. You just get that weight up and hope that you do not pass out.
Absolute strength refers to the level of effort (load lifted) with no relation to body mass. Where absolute strength is trained, the load is going to be at 1RM.
Whereas absolute strength does not consider body mass, relative strength does. Generally, you can calculate relative strength by dividing your body mass by your 1RM.
With speed-strength, there is a tendency for players and coaches alike to believe that they are training power. While there is a fine line between the two qualities, speed-strength still requires a significant amount of force in order to overcome the load on the bar. But, having said that, the load on the bar is ultimately irrelevant if performance on the field of play does not improve. So, a better definition of speed-strength is the physical ability to generate high force and do so at high velocity, hence the confusion with power.3 Generally speaking, speed-strength can be trained within the 80-90% range of 1RM.
As the principle of specificity suggests, specific strength refers to the motor skills required to perform a particular sporting movement. In essence, specific strength is the force that is capable of being exerted during sport skills, or imposed on somebody, as in the case of rugby. Many coaches will likely program specific strength phases as the general preparation period (GPP) approaches its conclusion.
The work of Frans Bosch focuses on the specific and often highly complex nature of sport skills. The motor pattern refers to the movement required, whereas the sensorimotor ability involves internal sensory input, such as muscle tension (slack). Therefore, it seems that specific strength training should not simply attempt to mimic the sporting movement but incorporate the sensorimotor demands.4
There are many resources regarding specific strength, none more useful than the original Special Strength Training (Verkhoshansky). However, a coach’s knowledge and, importantly, their understanding of their sport are both invaluable when considering specific strength training. A lot of research, while useful, is performed by scientists within a controlled environment.A coach’s knowledge and understanding of their sport are invaluable for specific strength training, says @JamyClamp. Click To Tweet
This is where a deep understanding of the sport that the coach works in is paramount. I will use the “jackal” position as an example from rugby. Done with precision and aggression, it is one of the most valuable assets to possess on the rugby field. Besides practicing the position during rugby training, players can supplement it with exercises performed in the weight room. However, that requires an understanding of the demands and experience with “jackaling.”
Why Strength Training?
It is correctly stated that strength alone does not mean that the player is more competent on the field. Having a standard of strength means that they are in a position to lift more with, hopefully, a greater velocity. The ultimate goal is for that player to make use of their weight room ability to affect the execution of their sports skills.
Does training lead to a better performance during the game or event?
If the answer is no, it is essential to address why.
Power requires strength. After all, power is the product of force and velocity. Now, just because an athlete is strong, it does not mean they will naturally be able to realize that strength in the form of power. Genetic makeup can dictate an awful lot in terms of muscle fiber types, tendon lengths, and body types, to name a few. Anaerobic power ability is more difficult to train than aerobic endurance ability. Mitochondrial density is relatively quick to increase. However, it is more taxing to alter the characteristics of a muscle and motor unit.
Strength endurance is the ability to produce and exert force over a prolonged period of time. There is an element of damage limitation with this strength quality because it is accepted that force will not be as significant as it is during low repetition training, but the goal is to maintain force output.
Production of Force
Rate of force development (RFD) is essentially what coaches improve and maintain. To increase RFD, the amount of force (ma) needs to increase, while reducing the time taken to displace an object. Broadly put, to improve RFD, it is only beneficial to train with greater loads (kg) and higher velocities; hence the popularity of velocity-based training (VBT).
As we sprint, the generated force is exerted into the ground. These forces are also known as ground reaction forces. In the case of sprinting, force is applied both vertically, resulting in flight time, and horizontally, resulting in meters gained. To run at speed, we have to minimize time spent in the air, as it is essentially time misspent, and maximize horizontal force. In short, there are a number of potential factors that contribute towards force production, none more prominent than neural drive and muscle architecture.
Reduction of Force
With force reduction, it is essentially a matter of being able to tolerate work around the musculoskeletal system. The premise of robustness largely centers on this quality because, simply put, if a player struggles to maintain a degree of postural integrity upon impact, they will likely find themselves with a problem. However, it is obviously unrealistic to expect a player to maintain “perfect” posture. I find the concept of robustness problematic because, ultimately (and funnily enough), the body is quite a rigid structure.
Landing mechanics also involve force reduction. A go-to example is the young player that has a relatively powerful vertical jump. However, that same player struggles to control their landing, as their ankles roll and their knees come together. To complement the more concentric, explosive action, it is important to be able to control the eccentric movement. An athlete’s training maturity, strength training, and time spent practicing landings will likely improve their ability to land efficiently. Interestingly, the collision that occurs during plyometric exercise, such as depth jumps, can contribute towards ossification.5 A mechanical load that is compressive in nature essentially generates the neurological impulses that stimulate the elicited adaptation.
Stabilization of Force
To explain stabilization, I have not encountered a better analogy than: “Can you shoot a cannon from a canoe?” You might be able to, but you would likely end up in the drink and your intended target would likely breeze on by. Therefore, being stable and in control of our movement lends itself to a more efficient utilization of force. For example, during the stance phase as the foot progresses from touch-down to mid-stance to take-off, the ankle absorbs a large amount of force. If the ankle becomes unstable, generally through pronation or supination, force is being lost. Generating force is an extremely valuable athletic quality; however, if stability is not present, that same quality is undervalued.
The Three General Determinants of Strength
Determinants of strength are essentially factors that contribute towards this physical quality. Broadly, they include central (nervous system) and peripheral (muscular system) contributors. However, strength involves a little more than simply increasing the cross-sectional area (CSA) of a muscle. Generally, there are three categories that will contribute towards, and determine, strength: biomechanical, physiological, and psychological.The 3 general determinants of strength are #biomechanical, #physiological, and #psychological factors, says @JamyClamp. Click To Tweet
Biomechanical Determinants of Strength
Forces are quantified within two categories: vector and scalar. Definitions of each can be found below.
- Vector: Magnitude (force production) with a specific direction (horizontal or vertical).
- Scalar: Magnitude (force production) without a specific direction.
As we apply force to an external object, such as the garden plot or a player on the rugby field, it is a vector because it has a direction. A mass is scalar, because it’s lazy and, without anyone pushing it, it stays still. As the Joker says; “All it needs is a little push.” By understanding that strength and force is essential if we wish to move objects with speed and efficiency, the importance of the component is further highlighted.
The force-velocity curve (FVC) falls within biomechanical determinants. Where force (N) is high, velocity (m/s) is low. Conversely, where force is low, velocity is likely greater. The types of force production, such as power and maximal strength, are placed throughout the curve. Power is often viewed as the “holy grail” of performance. It is shown to be sandwiched between strength-speed, where the magnitude of the lift is still quite slow but the force is relatively high, and speed-strength, whereby the velocity is noticeably greater. For the sake of generality, the main purpose of understanding the force-velocity relationship is to try to shift the curve towards the right.
Biomechanics is “the area of science concerned with the analysis of mechanics of human movement.”6 Ultimately, the length of our limbs can control a fraction of the lifts performed in the weight room. A taller individual, with a long femur, then has the task of pulling a load further to lockout, but the length of our limbs cannot be changed unless we take to them with a piece of sandpaper. Mechanically, it is a matter of adjusting according to the individual because they must make the most of their mechanics.
Physiological Determinants of Strength
Broadly, physiological determinants include central (nervous system) and peripheral (muscular system) factors. Central determinants are largely centered on the adaptation or, in some cases, the temporary maladaptation of the nervous system. Conversely, peripheral determinants tend to involve changes in the architecture of the muscle.
As the saying goes, “a larger muscle is more likely to exert greater force.” In practical terms, more forceful muscles tend to be larger muscles, but this is dependent on the type of training performed. A bodybuilder might have larger musculature than a powerlifter, but which individual generally lifts greater weight?
Aagard et al.7 monitored the response of human pennate muscle, which run parallel to their associative tendon, to a 14-week heavy strength training regime. Training load varied from three to ten repetition maximums (RM), until the latter weeks (10-14 weeks), where ranges varied between four and six RM. To summarize their study, the CSA of type 1 muscle fibers was not statistically significant, but that does not mean it was time wasted.I look at #fatigue as a crossover between physiological and psychological determinants for strength, says @JamyClamp. Click To Tweet
Linking back to structural training, it is the rep and set ranges that largely determine the effect that lifting has on muscle architecture. Training at 85-100% of a rep max is within the myofibrillar hypertrophy range; however, there will likely be the potential benefit of increased density. Conversely, as intensity increases and volume decreases (high rep/low set), loads used are usually much less in relation to %1RM.
Further to muscle architecture, it is well-known that endurance-based athletes are likely to be dominant in type 1 fibers, with slow twitch characteristics. Type 1 fibers produce less force, but they are capable of producing force over a prolonged period of time. Therefore, they lend themselves to strength-endurance training. Opposite to these, fast twitch fibers generate much larger levels of force. The dominance of particular fiber types progresses nicely into the way that genetics maintain a pivotal role in strength.
Much the same as our leverage potential, genetics are an element of performance that cannot be altered, or at least not cheaply or quickly. We can only make use of the ingredients that we have in season, so we must strive to optimize the product. Numerous products exist that allow for genotyping and, fortunately, I have completed a DNA test. As my knowledge does not yet extend far enough into the depths of genotypes, there a number of standout genes that could have an influence on strength.
Alpha-actinin-3 (ACTN3) is associated with filament sliding velocity8; therefore, a deficiency in this particular gene could reduce power-generating potential. To elaborate, Yang et al. studied the difference in allele frequency (ACNT3) between power (n=46) and endurance (n=194) athletes. They found variations amongst the two categories of athletes, although not significant, that promoted the athletic quality in which they competed. Essentially, if there is the luxury of genotyping, it is useful, but ultimately, we can generally tell if someone is likely to be power or endurance dominant—the “eyeballing” analysis.
Hormones are the mediators of the large majority of human processes. A significant fluctuation in hormonal balance can have detrimental effects either way. Hormones can be broadly categorized as being either anabolic, constructing, or catabolic, destructing. In the anabolic group, there are the infamous pair of testosterone and growth hormone, and their derivatives. Most noticeably, cortisol—also known as the “stress hormone”—is labelled catabolic. Epinephrine and norepinephrine, adrenaline and noradrenaline (for the British among us), respond almost immediately to strength training, as we strive to produce greater force.9
It is important to understand that endocrinology is not all lab coats and suspicious scientists. The hormonal response to training is critically important and the benefits can be obvious.
I look at fatigue as a crossover between physiological and psychological, and my opinion is substantiated by physiologist Tim Noakes. The typical indicators of fatigue are undeniable: hydrogen accumulation, due to lactate not being utilized as a fuel, causing the “burn”; a loss of homeostatic control; an increased partial pressure of carbon dioxide within arterial blood; and glycogen depletion, which reduces ATP turnover.10 They are some, but not all, of the potential physiological culprits behind fatigue. Psychologically, the Central Governor Mode suggests that fatigue is subconsciously controlled in order to prevent a “catastrophic” decline in performance. Essentially, we are naturally offering our best attempt at controlling homeostasis.
Psychological Determinants of Strength
While strength is primarily a physical component of performance, psychology will often play a pivotal role in the expression of the quality. To gain the full benefits of strength training, every element of a session needs to be executed with intensity, commitment, and effort.
Exerting force against a heavy object to prevent it from crushing us irrefutably involves a reasonable amount of effort. So naturally, at a particular moment in time, motivation has a significant role in the expression of strength in the weight room. I am sure we have all experienced training days where we know, after our first set, that we will likely be “embracing the grind,” as opposed to pressing and pushing like a knife through butter. This is where a coach earns a percentage of their bacon because, at times, it is just not sensible to adapt the session based on the player’s current condition, and this is hugely important because being stubborn and ignoring potential signs of fatigue is negligible.Motivation has a significant role in the expression of strength in the weight room, says @JamyClamp. Click To Tweet
A point where technology and motivation join forces is through the use of velocity-based training. Essentially, VBT provides knowledge of performance feedback on a rep-by-rep basis. Granted, an athlete who is relatively experienced in the weight room is likely to acknowledge when they are fatiguing but, with VBT, there is an objective measure that clarifies the issue. Linking back to motivation, sportspeople are largely innately competitive breeds, so a challenge to maintain or increase their velocity is valuable, as long as it is kept under control.
Intent to Lift
The hard-nosed coaches will likely bang the drum to this and I’m not saying it is wrong to attempt to ignite or, in some cases, reignite the fire. The intent that an athlete has to lift plays a pivotal role in the training outcome. But if there is a lack of intent during training, does it not seem logical to ask why? The boot camp “shouty shouty” approach might work for some, but I’ve found it often makes matters worse. As the cycle of performance contributors shows, strength is not just lifting big. As soon as we treat the athletes we work with like weightlifting robots, we lose ground. Take the time to understand why they are not lifting with intent because, if you understand their “why,” you can coach far more effectively.
‘Here, There and Everywhere’ Athletes
They are fired up and willing to crack their head against another player’s hip at speed, but they then simply exist, and cruise in neutral, during strength training. While it may be frustrating for the coach, it is not uncommon, so again, provide a “why” and highlight how the training will benefit them on the field both in the short term and, perhaps more importantly in the coach’s eye, in the long term.
“High-wired characters tend to suit high-wired sports.” (Nick Newman) I accept that this statement is a slight generalization. However, I think it runs true most of the time. Picture the start line before the 100-meter dash. Now, picture the start line before the 1500-meter run. I have noticed significant differences, and a coach can learn a lot from the personality of an athlete, and manage their approach. However, you should never cage athletes because of their personality characteristics. It is a balancing act.
Strength: An Important Ingredient, but Not the Only Ingredient
Overall, strength is a critical part of performing and doing so with efficiency, as well as doing it on a regular basis. Hopefully, there is an understanding that it is not a “deal breaker” in the sense that, without great maximal strength, a career will be washed away. Strength is a part of the recipe, but there are other ingredients required to bake a nice cake.
Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF
- Verkhoshansky, Y. and Siff, M. 2009. “Supertraining.” 6th ed. Verkhoshansky SSTM; Rome.
- Stone, M., O’Bryant, H., Garhammer, J., McMillan, J., and Rozenek, R. 1982. “A Theoretical Model of Strength Training.” NSCA Journal. 36-39.
- Bompa, T. and Haff, G. 2009. “Periodization: Theory and Methodology of Training.” Human Kinetics: Champaign.
- Bosch, F. 2015. “Strength Training and Coordination: An Integrative Approach.” 2010 Publishers: Rotterdam.
- Ohashi, N., Robling, A., Burr, D., and Turner, C. 2002. “The Effects of Dynamic Axial Loading on the Rat Growth Plate.” Journal of Bone and Mineral Research. 17 (2), 284-292.
- The British Association of Sport and Exercise Science. (Online). BASES. Available at: http://www.bases.org.uk/Biomechanics
- Aagard, P., Andersen, J., Poulsen-Dyhre, P., Leffers-Mette, A., Wagner, A., Magnusson, P., Kristensen-Halkjaer, J., and Simonsen, E. 2001. “A mechanism for increased contractile strength of human pennate muscle in response to strength training: changes in muscle architecture.” Journal of Physiology. 534 (2) 613-623.
- Yang, N., MacArthur, D., Gulbin, J., Hahn, A., Beggs, A., Easteal, S., and North, K. 2003. ACTN3 “Genotype is Associated with Human Elite Athletic Performance.” American Journal of Human Genetics. 73 (3) 627-631.
- Kraemer, W. and Ratamess, N. 2005. “Hormonal responses and adaptations to resistance exercise and training.” Sports Medicine. 35 (4) 339-361.
- Noakes, T. 2007. “The Central Governor Model of Exercise Regulation Applied to the Marathon.” Sports Medicine. 37 (4) 374-377.