First, muscle activation can be defined as 3 phases. Concentric, (shortening of the muscle), Isometric (no change in length) and Eccentric (lengthening of the muscle). This is termed triphasic. So in every dynamic repetition there is an isometric component.
There are two general types of Isometrics. Yielding Iso's and Overcoming Iso's. A Yielding Iso is where the athlete is trying to keep himself from lowering the weight or lowering the body. Holding a lunge position, holding a push up and holding yourself up in a chin up position are examples.
Overcoming Iso's would be trying to overcome an object. Pulling as hard as you can against a barbell that can't move. Pushing against a wall. Pushing or pulling on a barbell that is set on pins in a squat rack for a deadlift or a squat, would be two great examples.
Ray Eady, strength coach at the University of Wisconsin, talked extensively how he uses Isometrics, athletes can develop better deceleration with the use of Yielding Iso's and acceleration with Overcoming Iso's. Overcoming Iso's are Central Nervous System (CNS) intensive and should be used as you would a Max Effort type exercise.
Some of the research Coach Eady presented was that Iso's can contribute up to 5% more motor units. That it can be used to increase strength effectively at desired joint angles. Greater strength gains when combined with a dynamic movement. When combined with a dynamic movement you use the iso first as a potentiator, recruiting more motor units then normal, then do a dynamic movement to take advantage of this.
Some examples presented were as varied as you can get depending on goals. Hold the isometric for 7 seconds, rest 30 seconds and then go into a dynamic exercise.
Hold a yielding or overcoming iso for 20-40 seconds to work the hypertrophy angle.
Hold a joint angle for 8 seconds at several different angles to work on strengthening a injured bodypart or muscle.
Hold a yielding iso for max time to work on ROM using eccentric quasi isometric (EQI) principles.
A common parameter Coach Eady presented was 7 seconds iso/1 rep/6sec iso/1 rep/5 sec iso/1 rep...ect So he was combining isometric with full movement in an endurance type parameter.
Isometrics have many benefits, but there are a few drawbacks. There is a quick adaptation period, so shouldn't program them in for longer then 8 weeks. They require a lot of concentration, what you put in, is what you get out. They are hard to measure in terms of strength gains and progress.
Isometrics are a great tool to add into your strength training arsenal. Use wisely and they will help develop a healthier more athletic patient/athlete.
Some examples presented were as varied as you can get depending on goals. Hold the isometric for 7 seconds, rest 30 seconds and then go into a dynamic exercise.
Hold a yielding or overcoming iso for 20-40 seconds to work the hypertrophy angle.
Hold a joint angle for 8 seconds at several different angles to work on strengthening a injured bodypart or muscle.
Hold a yielding iso for max time to work on ROM using eccentric quasi isometric (EQI) principles.
A common parameter Coach Eady presented was 7 seconds iso/1 rep/6sec iso/1 rep/5 sec iso/1 rep...ect So he was combining isometric with full movement in an endurance type parameter.
Isometrics have many benefits, but there are a few drawbacks. There is a quick adaptation period, so shouldn't program them in for longer then 8 weeks. They require a lot of concentration, what you put in, is what you get out. They are hard to measure in terms of strength gains and progress.
Isometrics are a great tool to add into your strength training arsenal. Use wisely and they will help develop a healthier more athletic patient/athlete.
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