Differentiate Your Strength Training

By Dr. Michael Yessis

President, Sports Training, Inc.

   Do your players need more concentric, eccentric or isometric strength? Or, do they need more starting strength, explosive strength, speed-strength, absolute strength, limit strength or strength endurance? If you are like most football coaches, you probably have not given much thought to the kinds of strength that the players need. This is understandable since the different types of strength are rarely discussed or differentiated.

   However, knowing the differences between these different types of strength and which  position players need which specific types of strength can play a significant role in how effectively they perform on the field. For example, defensive linemen typically need more isometric and eccentric strength while offensive linemen need more eccentric and explosive strength. Backfield players typically need more starting and explosive strength. Some of them may need more stopping (eccentric) strength. 

   In my work with football players, especially on the high school and collegiate levels, I have found that while all players need more concentric, eccentric and isometric strength, they are also greatly lacking in starting and explosive strength. Because of the importance of these different kinds of strength and because many of these terms are relatively new to the coaching world, it is necessary to explain what each is. In this way, you can better understand why they are necessary and how they can be applied to specific players in specific positions.

   It should also be noted that most of these terms have been handed down from the former Soviets who did the most extensive theoretical and applied research in this area.  For more information on their training methods, which we are gradually adopting, see Secrets of Russian Sports Fitness and Training and the Fitness and Sports Review International (formerly known as the Soviet Sports Review).

   In order to do justice to the different types of strength and to present sufficient information so that you can successfully implement them in your training programs, I will discuss them in a two-to-three part article. In this first article I’ll examine core or basic strength consisting of concentric, eccentric and isometric type muscular contractions.

Concentric - Concentric strength training is the most common form of strength training. In this, you overcome a resistance - e.g., you move a weight through a certain range of motion. As you do this, the muscle shortens during the contraction. When using free weights or body weight, gravity is the opposing force that creates resistance. As an example, this would be doing the squat, bench press, etc. In running when you push off, you exhibit a concentric contraction in which the calf muscles contract to push the body forward. Note that in almost all strength and skill exercises, the concentric contraction is preceded by the eccentric contraction.

Eccentric - In the eccentric contraction, the muscle lengthens as it develops tension. In essence, it returns to its original length from a shortened state created by the concentric contraction. In the eccentric contraction you can generate up to 50 percent more tension than in the concentric contraction. As an example, if 100 lbs. is the maximum you can handle in the concentric regime, in the eccentric regime you can handle up to 150 lbs. or 50 percent more weight.

   Backfield players and receivers who do considerable running, need the eccentric strength during offensive drives. After the foot makes contact with the ground, there is flexion in the ankle, knee, and hip joints to not only absorb some of the landing forces but mainly to withstand the forces. When the leg joints undergo flexion, the extensor muscles of these joints undergo lengthening. But, as they lengthen, they create greater tension to eventually stop the down movement so that the player does not sink too low. If he has a great amount of up and down motion, he wastes a great deal of energy and the running is slower. In addition, as the muscles develop greater tension in the eccentric lengthening or yielding-type contraction, they prepare the muscles for the concentric contraction which is seen in the push-off. 

   Defensive linemen need greater levels of eccentric and especially isometric strength to hold off offensive charges and to protect the quarterback. They must be strong enough to stand their ground and repel and hold off the offensive players. Offensive linemen, on the other hand, need more explosive strength. They must be able to hit quickly and powerfully before the defense has a chance to react. In addition, they must have sufficient levels of eccentric and isometric strength to maintain their position and not be pushed back or to the side. Greater levels of eccentric strength are also essential for developing greater explosive power.

Isometric - The isometric contraction is seen in all actions even if only momentarily. Whenever there are repeat muscular contractions, the muscles undergo all three types of muscular contractions. The eccentric contraction is for slowing down and bringing a movement to a halt at which point the isometric contraction takes over momentarily prior to the concentric contraction. As an example, and this is especially important for backs and receivers, when the foot is in contact with the ground during the support phase, the muscles undergo an isometric contraction to hold the leg position while you push off and the body moves forward. 

   The isometric contraction can be up to 20 percent greater than the concentric and can thus withstand great forces. In general, the tension developed in the eccentric contraction stops the movement so that you exhibit an isometric contraction during the holding period. This is why the isometric contraction is often known as a holding or maintaining- type contraction.

   Even though all three muscular contraction regimes are involved in the execution of all skills, the muscles do not get stronger in each type of contraction equally. The reason for this is that each of the muscular contractions do not experience overload which is a prerequisite for gains in any type of strength. To gain greater concentric strength, you must use greater amounts of resistance (weights) to constantly tax the muscles above what they are accustomed to so that they can adapt and respond by becoming stronger in the concentric contraction. The same applies to the eccentric contraction. However, because the eccentric contraction can withstand up to 50 percent greater force, you must use more than 100 percent resistance. 

   To illustrate, if you are doing the squat exercise and you weigh 150 lbs., when you lower your body the eccentric contraction is not maximal. It is sufficient to withstand your weight but in order to become stronger in the eccentric contraction, you have to place dumbbells in your hands or a barbell on your shoulders and then lower your body so that you use more than body weight (or your strength level) to have a stronger eccentric contraction. You then produce the overload needed to develop greater eccentric strength.

   The same applies to the isometric contraction. Because it is stronger than the concentric, you must generate greater force in order to have a stronger contraction.  This is done by holding a position and increasing the muscle tension by pushing against the resistance (immovable object) for up to six seconds so that the muscle develops greater tension without movement.

   In addition to the above factors, each player should be analyzed on an individual basis to determine exactly what kind and how much additional strength he may need. In general, such differentiation is usually reserved for the older athletes as the very young athletes - up to about 16 years of age - are usually best served with standard weight training regimes. How much weight, how many sets and reps, and some of the best exercises for each type of strength will be addressed in future articles.

Dr. Michael Yessis is President of Sports Training, Inc. he can be reached at his web site – www.DrYessis.com – or his email: dryessis@dryessis.com.