Jun 11th, 2012
Concentric Versus Eccentric Muscular Action
It is vital to understand the different types of muscular actions that take place during resistance training. Taking it a step further, understanding how those actions are used during a sport and/or activity. Gaining insight into muscular actions can create greater athletic performance and/or fitness. Resistance training invokes muscular adaptations that lead to greater levels of athletic performance; a leaner and sexier physique; and an overall feeling of better health. Muscular actions allow for these adaptations to occur, although each action is different in nature.
There are three types of muscular actions; eccentric, concentric, and isometric. Only concentric and eccentric are dynamic muscular actions. These two actions are considered dynamic because muscle-length tension relationship changes while force is being applied (1). During training, the majority of resistance exercises and apparatuses are developed to allow athletes / lifters to perform both the eccentric and concentric muscular action in sequence of each other. There is a positive correlation between this training and fitness / athletic performance because real life movements often require both actions in sequence.
Eccentric muscular actions are when a force is being generated upon skeletal muscle and the muscle fibers lengthen during contraction. Better yet, decelerating a force being applied upon or slowing down the body or body part. Visualize squatting down during a squat, this is an eccentric muscular action. The eccentric muscular action is essential in regards to muscular growth during training. Even though it is necessary the eccentric action is considered the most dangerous muscular action of the three. The majority of non-contact injuries occur during eccentric muscular actions because it typically generates higher amounts of mechanical stress than concentric or isometric muscular actions. However, the NSCA states that elevated levels of mechanical stress results in higher amounts of muscular stimulation / growth (1). Muscular growth leads to strength, power, speed, quickness, reduced injury, and a lean physique. Other less favorable side effects of eccentric training are muscular soreness, fatigue, and inflammation. These side effects can be avoided if concentric training is solely performed.
Concentric muscular actions are when skeletal muscle are pushing, providing pressure, and/or applying force upon an object and the muscle fibers shorten during the contraction. Visualize standing up from a squat, this is a concentric muscular action. Concentric muscular actions are vital in regards to athletic performance. These actions propel athletes during sprinting, jumping, hitting, etc… In a sport such as swimming, where concentric muscular actions are the only actions used while in the water because gravity is not in play, it is imperative to utilize and develop a higher force capability / output. Movements such as the high pull or one arm dumbbell snatch that typically only require concentric action can be advantageous to minimize soreness while increasing muscular adaptations. However, the majority of sports require athletes to utilize a muscular / tendon pre-stretch, better known as “the stretch shortening cycle,” which involves an eccentric action followed by a concentric action.
Although eccentric actions lead to the greatest amounts of muscular adaptations / growth, concentric focused training has also shown favorable results. Recently a study found that after 8 weeks of concentric-isokinetic resistance training participants strength and size went up (2). This study, along with other research, supports concentric focused training as a way to increase muscular strength, size, and performance. The added benefit of concentric focused training is a decrease in muscular fatigue, strength loss over repeated bouts, and soreness.
Concentric based training may be favorable during in-season training or weeks leading up to competitions. The lack of soreness and fatigue allows athletes and persons alike to maintain their sport specific training without losing muscular adaptations. However, in order to achieve the greatest amount of sport performance or fitness performance training, persons should continue to engage in eccentric, isometric, and concentric training. There are very few movements, if any at all, that do not require each of the three actions.
Here are a few lower body movements that lead to reduced injury, maximal amounts of muscular growth, and engage in all three muscle actions:
• Squats (back, front, or dumbbell) that engage in a full range of motion (ROM); a full ROM requires proper technique and progression.
• Single Leg Bench Squats are movements that require the athlete to squat on one leg until their glutes are rested upon the bench; be sure to limit the amount of forward lean so that the knee never passes the front of the toes.
Here are a few concentric focused movements that can increase power output with less soreness, loss of strength, and muscular fatigue:
• Heavy Rope drills are truly concentric; heavy ropes will not move until force is imposed upon them through concentric muscular action.
• High Pulls are Olympic power movements that require the athlete to explosively deadlift the barbell from the ground and pull it as high as they can in an upward motion until it passes their mid-section; upon completion of the pull the athlete allows the barbell to fall to the floor. This movement should be used with Olympic bumper weights and should only be performed after learning how to deadlift.
Athletes please note that concentric style training is a great way to train leading up to an event or competition. During the last weeks leading into competition soreness is not warranted. Seek out an educated strength and conditioning coach that understands in-season training. Your goal should be to emphasize concentric action lifts to maintain, even slightly increase, strength and power. However, it is always vital to continue to perform eccentric movements to ensure optimal performance, health and longevity.
1. The Essentials of Strength Training and Conditioning (3rd edition).
By, National Strength and Conditioning Association
Editors: Thomas R. Baechle and Roger W. Earle
©2008, 2000, 1994
2. Effects of unilateral concentric-only dynamic constant external resistance training on quadriceps femoris cross-sectional area.
Housh DJ, Housh TJ, Weir JP, Weir LL, Evetovich TK, and Donlin PE.
Journal of Strength and Conditioning 12: 185-191, 1998
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