Personal trainers are being called on with increasing frequency to work with athletes, people with disabilities and individuals involved in various specialty areas. In essence, today’s multi-purpose gym is becoming the center for multiple populations. This, in turn, creates the need for multiple kinds of trainings especially strength training and the development of specific physical abilities.
However, most personal trainers and instructors do not have the backgrounds to work with people on needs other than basic bodybuilding and weight loss. Bodybuilding is only one phase of the total training of athletes and others whose training is dictated by the sport or occupation in which they participate. Because of this it is important to broaden the scope of personal trainers so that they can be more effective in working with people with different strength needs and especially athletes who require more than one type of strength and different kinds of trainings.
What is Strength? Strength is usually defined as the ability to overcome a resistance, ie, to lift or move a weight through a particular range of motion or to generate force. This is only a basic definition since it is possible to distinguish many types of strength and different displays of strength by athletes in various sports. For example, strength is exhibited differently by bodybuilders, weightlifters, powerlifters and athletes involved in power (speed-strength) sports.
In addition, a certain kind of strength is needed to become quicker and more explosive. Another type of strength is needed to be better able to overcome a heavy weight in a slow movement as opposed to strength needed to overcome a maximal or submaximal resistance in a fast movement. Still another type of strength is needed to be better able to execute sports skills more effectively.
At first glance, you may say that in all of these instances you need the same of strength, and, to a certain extent, this is true, especially with beginners, ie, individuals who have not been involved in serious weight training. However, developing only one type of strength will not bring about favorable results in performing all the actions and movements required by athletes in different sports. To better understand this concept, it is necessary to look at the different types of strength.
Concentric Strength This is the most common type of strength displayed in the gym. In concentric strength you overcome a resistance and the muscle fibers and tendons shorten during the contraction. Examples of concentric strength in which you overcome a resistance include basic exercises such as the biceps curl, squat, overhead press and lat pulldown.
Eccentric Strength In eccentric strength the muscle lengthens during its contraction. As the muscle lengthens it develops tension which when it becomes great enough, stops the movement. For example, in the biceps curl, you exhibit a concentric contraction when you raise the weight and an eccentric contraction as you lower the weight. However, in the return movement, the intensity of the eccentric contraction is not as great as the concentric.
Since gravity is the force pulling the weight down, the eccentric contraction is used to control and stop the movement at the end of the range of motion. The eccentric contraction which can be 50% stronger than the concentric, is mainly a guiding and stopping type of contraction. Also, as you raise the weight in the concentric contraction, the antagonist muscles contract eccentrically to control the movement pathway and to provide greater joint stability.
The eccentric contraction is used a great deal in other forms of movement control and stopping. For example, when you jump down from a height, upon landing, the eccentric contraction of the leg muscles slow you down and stop you from collapsing. When receiving a weighted ball, the eccentric contraction cushions and stops the movement. It controls and helps to dissipate the forces as you catch and bring the ball in toward the body.
The eccentric contraction is also the key to preparing a muscle for an explosive concentric contraction. This will be explained in further detail in speed-strength and explosive strength. In essence, the eccentric strength plays a role in all dynamic movements and especially in maximal resistance and speed movements. For example, if you lift a maximally heavy weight slowly, there is co-contraction, of the agonist (concentric) and antagonist muscles via the eccentric contraction.
In sports skills such as in baseball pitching or throwing, when you take the backswing you place the agonist muscles on eccentric stretch so that they can contract with greater force in the forward throw. In the forward throw, the muscles contract concentrically but the antagonist muscles undergo a strong eccentric contraction to slow down and stop the arm after the ball is released. If the antagonist muscles do not have sufficient eccentric strength, injuries can easily occur. In fact, many if not most injuries that occur in sports, occur during the eccentric strength stretch phase, not during the concentric overcoming resistance phase.
Isometric Strength Isometric strength is the amount of strength you can exhibit at a single point in the range of motion. In the display of isometric strength, there is no joint or limb movement, although there is some shortening of the muscle fibers and tendons. An example of an isometric contraction is holding a weight in a particular position. The muscles create tension to maintain the position, but there is no movement. Isometric strength can be up to 20% greater than concentric strength.
Isometric strength is exhibited in every exercise. For example, when you do the biceps curl, after reaching the top position you must stop movement of the weight in one direction before reversing and returning to the initial position. When you stop, you exhibit the isometric contraction. A recent trend is to hold the maximally contracted muscle for one to two seconds in the isometric regime to develop even greater tension for more strength and muscle mass.
Speed-strength Speed-strength, as the term implies, is strength displayed with speed. The best example of this in the iron sports is weightlifting (snatch and clean and jerk). Because of the extremely fast execution of these two lifts, which also require maximal resistance and high levels of coordination, weightlifters are often considered the fastest or most powerful athletes in the world.
Most examples of speed-strength are found in sports, as for example, the ability to execute a quick jump. The faster the jump is executed, the higher the athlete will go. In this, the jump landing and take-off are executed in less than two-tenths of a second. Other examples include the swinging of a bat or club as in golf, throwing implements ranging from a javelin to a baseball, punching and so on. The athlete must execute the skill in the shortest amount of time with the greatest force possible in these sports activities.
In execution of most sports skills and in strength training, neuromuscular coordination must also be taken into consideration. Athletes must exhibit a high level of neuromuscular coordination to execute a complex skill in addition to executing it in the shortest amount of time and with the greatest amount of force. Very often, the effectiveness of the neuromuscular coordination determines the amount of speed-strength that is exhibited.
It is worthwhile to recall that in the initial stages of basic strength training, early gains in strength are due to neuromuscular gains, not physiological changes to the muscle. These do not occur until a person has been exercising for at least several or more weeks.
Speed-strength is a relatively new term in the U.S. Most often it was known as power. But because power has come to mean everything from a slow lift with maximum resistance (powerlifting), to an explosive contraction (light to heavy resistance moved with maximum speed) I recommend not using this term, until there is general agreement as to its definition. In a technical sense power should be the same as speed-strength, ie, maximum force exhibited over a distance executed at a certain speed of movement. The faster the work (force x distance) is executed, the greater the power.
However, this definition is rarely used in the gym. Most often it implies a maximal weight moving at a slow speed in which somehow the muscle fibers are supposed to be contracting explosively. You only have to try to move the weight fast for it to be an explosive or “power” lift. This is a non-scientific interpretation that leads to misunderstanding and confusion.
Absolute Strength Absolute strength is defined as the maximal amount of weight that you can lift one time. It is usually reserved for the concentric contraction but can also apply to the eccentric and isometric. For example, in the typical measurement for hand strength you squeeze a dynamometer as hard as possible. The initial contraction is concentric but when you reach the end point, you squeeze as hard as possible in the isometric contraction to display absolute strength. In the iron sports, powerlifting comes closest to displaying absolute strength.
In this sport, the athlete lifts the maximum weight possible very slowly. It is concentric strength but yet has an element of the isometric since the athlete must hold the end position for a few seconds before the signal to stop is given. This display of absolute strength is volitional act, ie, it is the maximum strength generated under your own will power.
Limit Strength Limit strength relates to the amount of weight that you can overcome when inhibitions are removed. For example, when an athlete is under the influence of drugs or is hypnotized he is capable of lifting more weight than in his conscious state with his own will power. Researchers have shown quite conclusively that it is possible to display more strength when inhibitions are removed.
For example, an individual may have fear of not being able to lift a certain amount of weight. When the fear is removed they become capable of the lift. There are even many examples on record of people who have lifted cars off their loved one when the car jack failed and the car came crashing down on the person. There was physical damage done to the person lifting the car (vertebrae were fractured), but these people were capable of displaying much greater strength than they ever could volitionally. This is limit strength. Research is also beginning to indicate that it is not only the muscles that are involved in displaying strength, but the connective tissue, ligaments and tendons also play an important role.
Relative Strength Relative strength applies to lifting your maximum weight in relation to your body weight. It is a useful method for comparing strength among different individuals. For example, if a person weighing 200 pounds is capable of doing only one pull-up, he is capable of lifting one pound of weight per pound of body weight. If another person weighing only 100 pounds cannot pull-up 200 pounds in one rep but can do two pull-ups, he also lifts 200 pounds of weight.
Thus, he too is capable of lifting two pounds of weight per every pound of body weight. Thus, they are equal in relative strength but not in absolute strength. The 200 pound person is capable of exhibiting greater absolute strength.
All too often tests of strength do not differentiate the amount of resistance overcome per pound of body weight. Instead the tests rely either on the number of repetitions or the total amount of resistance overcome one time. For example, in many fitness tests you score higher if you do more repetitions of the pull-up.
But if this is to be a true test of strength then the 200-pound person in the above example who could only do one pull-up would get a poor grade but may have greater strength in comparison to persons who score better with more reps. In such cases, relative weight is a much more accurate method of equating individuals.
Strength Endurance Strength endurance refers to the number of repetitions that you can execute with a sub-maximal weight. In other words, you can exhibit the same amount of strength for a certain number of repetitions. Usually it is measured after reaching 20 or more repetitions. Strength endurance also applies in execution of sports skills, as for example, being able to exert the same amount of force in the push-off for a hundred or more strides.
It can also refer to a golfer who is capable of exhibiting the same amount of force when hitting drives or other shots for 18 holes. Note that very often high scores in tests of strength or fitness are equated to high numbers of repetitions done. More accurate would be to state that these are tests of endurance.
Starting Strength Starting strength refers to the amount of force that you can generate when first starting a fast or explosive movement. It applies to athletes in various speed-strength sports including weightlifting. The greater the starting strength, the faster and sharper is the rise in force being applied. An example of starting strength is a sprinter coming out of the blocks or a weightlifter beginning his lift.
Explosive Strength Explosive strength is the ability to maintain an initial, quick explosive contraction of a muscle. Explosive strength can be generated using little or no resistance, moderate resistance or maximum resistance. Jumping using only body weight or throwing a baseball are examples of light resistance while throwing the shot, jumping with dumbbells in the hands and throwing and catching medicine balls quickly are illustrative of moderate resistance. The weightlifting events and quickly receiving and repelling heavy medicine balls are examples of heavy resistance.
The lighter the implement that you have to move and the shorter the distance over which force has to be applied, the more important is starting strength. The heavier the resistance and the greater the distance, the more important is explosive strength. Keep in mind that great distance here means only inches.
In general, explosive strength is a combination of eccentric, isometric and concentric strength. The muscle must first be prepared eccentrically so that it has great tension. It then switches to the isometric and then immediately into the concentric so that the total amount of time involved is approximately 0.15 seconds or less. Because of the short amount of time involved, this maximal force contraction is called explosive.
Dynamic Isometric Strength This is a relatively new addition to the arsenal of different types of strength that was coined by the Russians. They found that before the muscle can literally explode in the concentric contraction, after undergoing a strong eccentric contraction, it must undergo an isometric contraction which then quickly switches to the concentric. In other words, the isometric contraction is used to a great extent to prepare the muscle for the explosive concentric contraction. The muscle does not simply switch from the tensed eccentric contraction to an explosive concentric contraction.
Even though the muscle is under isometric contraction (when the movement is going to be reversed), it becomes dynamic for a very brief time period as it switches into the concentric. It is distinguished mainly because this quality can be trained separately from the usual methods applied.
General Strength General strength applies to overall fitness conditioning. In general strength you do exercises to develop all the major muscles and joints of the body. The main purpose is to strength the muscles and joints of the body to become more fit and to prepare the body for special strength and more explosive type exercises.
Special Strength Special strength is very specific to sports, or more accurately, to execution of specific sports skills. The special strength exercises have very specific criteria.
1. The strength exercise must duplicate the same motor pathway (technique) as in the execution of the particular skill or portion of the skill. 2. It must duplicate the exact range of motion in which the strength is displayed in execution of the sports skill. 3. The special exercise must involve the same type of muscular contraction as seen in execution of the sports skill or in a portion of the total skill.
For example, a push-up or a pull-up may be effective for strengthening of the shoulder joint muscles but they are not specific to the golf swing or sidearm throw in which the arm movement pattern is distinctly different. The push-up or pull-up in this case would be a general exercise with the actions taking place in the anterior-posterior plane. In the golf swing and sidearm throw the movement pathway is diagonal or horizontal across the body. Thus to be a special exercise strength must be developed in the same pathway as in the actual sports skill.
Functional Strength Functional strength is included here mainly because of the increased use of this term in the fitness and sports fields. Most often functional strength is used for exercises that develop strength to enhance one’s sports performance. To do this, however, the exercises must be special strength exercises. But, most “functional” exercises as described in the popular literature do not fulfill the criteria as stated above for special strength exercises.
Functional strength should apply only when you develop strength in a manner that will have an immediate effect on performance. Special strength exercises accomplish this task; without the specific criteria in effect, the exercise cannot be functional. Merely involving the same muscles in an exercise as used in a sport does make the exercise functional or specific to the sport.
To illustrate, many people do squats to improve their running or cycling performance. Both of these sports involve the same muscles as are used in the squat. However, if you do the squat and only participate in running, when you switch to cycling, you will become very sore because of the different way in which the same muscles are involved.
Any specificity here would be related to the aerobic component which would be the same for both of these endurance-type sports. In other words, the breathing requirements would be the same in both sports. The development of the respiratory muscles would enhance both cycling and running as well as other endurance type sports. The same does not hold true for the muscles that are involved in skill execution.
Merely doing exercises that involve the same muscles as are involved in the sport does not mean that they are specific or functional. They are good exercises that make the person more fit which in turn may have a positive effect on sports performance. But for the greatest transfer of strength and improvement in the sport, the exercises must be special. They can then be considered functional.
Relationships Between Different Types of Strength Even though the different categories of strength are quite distinct, they are all interrelated. For example, absolute strength is the basic strength that is typically developed mainly because it influences speed-strength, starting strength, strength endurance and other types of strength. The greater your levels of absolute strength, the greater can be your levels of speed-strength, starting strength, explosive strength, etc.
But, simply increasing absolute strength does not guarantee that you will continue to get greater levels of speed-strength or some other type of strength. Each is a separate quality and must be trained differently than absolute strength. Their close relationship exists only in initial strength training.
Age and level of training also play an important role in the development of different types of strength. For example, when a young person who has not been involved in weight training, goes on a strength training program, there will be a concurrent increase in speed-strength, strength endurance, explosive strength, absolute strength, etc. However, a person who has been in serious training for several years and who has already developed a high level of absolute strength will find that further increases in absolute will have a negative effect on related forms of strength that have a speed component. At this time it is necessary to supplement the absolute strength training with speed-strength training in order to develop a more explosive type muscular contraction.