Regulating velocity during a resistance exercise is a form of isotonic exercise, except that a certain speed must be remain constant for a portion or the entire length of the exercise. There is equipment that forces you to travel at a constant speed no matter how much force you apply, and there are methods of movement that you can include in any exercise to make you keep a constant velocity throughout each rep.
Benefits of Regulating Velocity
The American College of Sports Medicine notes that regulating the velocity of a resistance exercise helps in several ways. Regulating the velocity allows the muscle to strengthen equally throughout each linear point of the motion. Regulating velocity removes the opportunity to use momentum to move the weight, which ensures your muscles produce all the effort. It limits the opportunity for injury, and is significantly helpful in rehabilitative exercises.
Isokinetic Machines
The National Strength and Conditioning Association states that isokinetic machines force the user to move at a set speed, and typically isolate a muscle group. You can find these machines mainly at rehabilitation centers and physical therapy offices. The machines react to the force you apply against the resistance, and then varies the resistance it pushes back on you with to maintain a constant velocity throughout the entire range of motion.
Negatives
Performing negatives correctly will regulate the velocity you move at during the eccentric portion of the exercise. The eccentric portion means your muscles lengthen or stretch, and this portion is usually more physically demanding on the muscle fibers, reports the American College of Sports Medicine. Exercising using negatives is one of the simplest ways to regulate velocity without the use of expensive isokinetic machines. You must control the eccentric portion by moving slowly through the entire elongation phase, and then quickly performing the concentric portion of the workout. You can maintain your eccentric velocity by using a count to dictate where you should be during the motion. Use a five to 10 second count when performing negatives.
Positives
Positives will have you control the the shortening of the muscles, known as the concentric portion. You use the same motion and time parameters for positives as you would for the negatives. Momentum can interfere with many concentric portions of an exercise -- such as bouncing off your chest in the bench press -- and performing positives eliminates that opportunity. This allows for the muscle to be worked equally along the entire concentric range of motion, reports the National Strength and Conditioning Association. You will use a five to 10 second count when performing positives.
References
- "Essentials of Strength Training and Conditioning,"; Thomas R. Baechle, Roger W. Earle; 2008
- "ACSM's Guidelines for Exercise Testing and Prescription, 8th edition"; American College of Sports Medicine; 2009
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