Keys to Developing Maximal Strength and Power
We often discuss the five biomotor skills (speed, strength, flexibility, endurance, coordination) when discussing the fundamentals of both speed and athletic development. But the most important of these skills, in terms of enhancing speed or overall athletic ability is strength. There is a ceiling where progress will stop if an athlete does not actively develop physical strength. Simply put, ‘strength’ can be defined as an ability to produce force (Siff 2001). But strength is one of those terms we frequently use as an umbrella term to describe it’s many varied functions. Ultimately, strength can be expressed using different muscle actions.
These actions can take four different forms:
- Isometric – the muscle gains tension, but does not appreciably change its length
- Eccentric – the muscle gains tension and lengthens
- Concentric – the muscle gains tension and shortens
- Plyometric – where a concentric action is immediately preceded by an eccentric action – therefore taking advantage of the stretch shortening cycle
There are a number of factors involved in muscular strength. But two factors play the most significant role in activation and gradation of strength. They are: the number of motor units recruited and the frequency of motor unit activation. Normally, these factors work together to increase force production, but the exact degree to which one functions over the other depends on the amount of force required to do the job and the size and type of muscle being activated (Stone 2002).
Let’s look at some of the neuromuscular factors that contribute to strength production.
The first factor I presented was that of motor unit recruitment. Most scientists agree that an untrained muscle can not be fully activated. Athletes and programs not engaging in active strength development are essentially leaving motor units ‘dormant’ within the muscle. Therefore, strength training will lead to a greater activation of that muscle (waking up the dormant motor units), which leads to strength production.
Synchronization of these motor units also has an effect on muscle force. During ‘normal’ activity, motor units do not fire synchronously. But, as the maximal level of strength is approached, some motor units are activated at exactly the same time as other motor units, leading to increased efficiency of the muscular activity (Stone 2002).
With this understanding of motor unit involvement, we must consider both intra and inter muscular task specificity. Intramuscular task specificity addresses specific patterns of activation for motor units while inter-muscular task specificity addresses the interaction of activation among muscles during a particular task. These patterns of activation can change with very small alterations in movement pattern or with changes in velocity (Enoka, Semmler 2000). As coaches this tells us that our program design for strength and power training should be taken from the standpoint of ‘movement specific’ versus just training a particular muscle or group.
This, in part, is where we get the term ‘functional’ training because we want the activities that we use to develop strength and power to have transfer in training effect to athletic movement. While many movements are not going to be identical to that we would see during athletic competition, we must take a broader view and look at the patterning of the movement in terms of the previously discussed elements of muscular activation.
Reflex and stretch shortening cycles (SSC) can also enhance force production when used more efficiently. The SSC is essentially a plyometric movement where an eccentric action immediately precedes a concentric action. Some say that improved maximum strength can enhance the concentric part of the SSC (Cronin 2000). Enhancing the overall effectiveness of the SSC is a foundational necessity with athletes involved in activities like sprinting and jumping. We can make significant gains in speed, height and distance by carefully incorporating plyometrics into our workout plan. However, careful adherence to safety and mechanics is essential or serious injuries can result.
Another factor in strength development is that of motor unit type. Many studies indicate that a large proportion of type II muscle fibers can serve as a significant advantage in dynamic force production even when other factors (body type, mechanics, etc.) are taken into consideration. Some athletes are just incredibly strong, fast, powerful, etc. even when generally untrained or trained poorly. We often see that sprinter or jumper with terrible form and even worse coaching, yet they go out and destroy their competition. Many would argue that these athletes possess an abundance of these type II fibers. In lay terms we call these athletes ‘freaks’. The best way to compete with athletes is by using explosive strength training in our own programs as this type of training appears to increase the ratio of type II:I muscle fiber cross sectional area.
Biomechanical and anthropomorphic factors such as muscle architecture, insertion points, height and limb length all can alter the mechanical advantage of the intact muscle lever system (Stone 2002). What does that mean exactly? Some people are simply built for speed, strength and power more than others. We have all experienced working with the athlete who works harder than everyone else, but just isn’t fast or can’t make equal improvements in strength, when compared to their less committed peers. Mechanically speaking, we are not all created equal. Skilled weightlifters possess a high body mass to height ratio compared with other athletic groups. If a tall athlete and a short athlete both have the exact same muscle mass and volume, the shorter athlete will have the greatest muscle cross section and will therefore be able to generate greater muscular force.
Ever notice how shorter athletes seem to be better at shorter sprint events, have a faster start, change directions quicker, run a faster 40, etc? It is the aforementioned anthropomorphic and biomechanical factors that cause this. Taller athletes, with longer limbs, can not generate the same degree of force to ‘get going’ like their shorter (and otherwise equal) counterparts. What’s the solution for those at a mechanical or anthropomorphic (body type) disadvantage? Hypertrophe development, the result of strength training, raises the muscle’s potential for force production.
One final neuromuscular factor whose effect on strength capability must be considered is that of neural inhibition. Inhibition can come in two forms: conscious and somatic-reflexive. Conscious inhibition stems from the perception (regardless of the accuracy of this belief) that attempting to lift a particular weight will cause injury. For example, if an athlete has never dead lifted before and is told to attempt a 500 pound lift, it’s more than likely that this athlete will take a pass on making the attempt. (And rightly so!)
Somatic-reflexive inhibition is the result of feedback from different joint and muscle receptors. This is likely one of the body’s protective mechanisms and this type of inhibition will reduce muscle tension during maximal and near maximal lifts. Solution? Strength development can reduce receptor sensitivity and is responsible (in part) for achieving larger levels force production.
We understand now the Neurological factors involved in strength development. And we understand that strength is the binding force of long term athletic improvement. But beyond pure strength, a successful athlete must also possess power, i.e. ‘explosiveness’, so that his/her peak force can be produced rapidly. This fact is even more pronounced when you consider the fact that an elite male sprinter has an average foot contact time (amount of time foot spends on the ground) of .087 seconds.
Further, activities requiring a rapid change of direction and acceleration (i.e., agility) depend on bursts of high power output. Therefore, it is the output of power that is arguably the most critical factor in separating the winners from the losers in any athletic activity.
The symbiotic relationship between strength and power is fundamentally important. According to Stone (2002):
- measures of max. strength and power have moderate to very strong correlations
- the strength of the relationship, in part, depends upon the mechanical similarity of the measures
- although maximum strength influences power output at light resistances, its effect on power appears to increase with load
- periodized training and its variations can offer distinct advantages
From this we can conclude that power/explosiveness can be enhanced through the development of absolute strength.
Additionally, there are several different factors that impact the development of an athlete’s explosive qualities. Maximum strength, fatigue levels and aerobic training must be taken into consideration when designing any athletic development program:
Common sense tells us that maximum strength can have a positive effect on explosiveness. However, in developing this trait, we must consider the impact that two forms of fatigue will have on the long term effectiveness of this training. They are: degree of fatigue (occurs within a training session) and degree of residual fatigue (happens between sessions). It is important to note that continuous, high intensity training can lessen maximum strength and explosive strength in as little as 2 weeks. This results in athletes losing the ability to maintain proper technique and mechanics, diminishing entirely their ability to be ‘explosive’.
Athletes engaging in speed/power sports, or who train to develop maximum strength and power must avoid activities like distance running and other low intensity aerobic training. These activities, as I have said on countless occasions, will reduce maximum strength and power. There are many other recovery modalities and training activities that will facilitate the appropriate aerobic and work capacity required, in addition to helping enhance strength and power.
As coaches, trainers, athletes, etc., developing these traits starts with understanding the varied mechanisms that contribute to them, as well as those activities that detract from their effectiveness. Thus incorporating an appropriate, individualized and efficient training methodology will elicit the greatest improvements in both strength and power in every athlete.
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