DYNAMIC EXERCISE TECHNIQUES
Two of the most common dynamic exercise techniques are constant resistance exercise and variable resistance exercise. Both exercises are extremely effective for building muscular strength and endurance.
• Constant resistance exercise uses a constant load (weight) throughout a joint’s full range of motion. Training with free weights is a form of constant resistance exercise. A problem with this technique is that, because of differences in leverage, there are points in a joint’s range of motion where the muscle controlling the movement is stronger and points where it is weaker. The weakest point in the range limits the amount of weight a person can lift.
• In variable resistance exercise, the load is changed to provide maximum load throughout the entire range of motion. This form of exercise uses machines that place more stress on muscles at the end of the range of motion, where a person has better leverage and can exert more force. Use elastic bands and chains with free weights to add variable resistance to the exercises.
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Athletes use four other kinds of isotonic techniques, primarily for training and rehabilitation.
• Eccentric (pliometric) loading places a load on a muscle as it lengthens. The muscle contracts eccentrically to control the weight. Eccentric loading is practiced during most types of resistance training. For example, you are performing an eccentric movement as you lower the weight to your chest during a bench press in preparation for the active movement. You can also perform exercises designed specifically to overload muscle eccentrically, a technique called negatives.
• Plyometrics is the sudden eccentric loading and stretching of muscles followed by a forceful concentric contraction a movement that scientists call the stretch-shortening cycle. An example would be the action of the lower-body muscles when jumping from a bench to the ground and then jumping back onto the bench. This type of exercise helps develop explosive strength; it also helps build and maintain bone density.
DYNAMIC EXERCISE TECHNIQUES Photo Gallery
• In speed loading you move a weight as rapidly as possible in an attempt to approach the speeds used in movements like throwing a softball or sprinting. In the bench press, for example, speed loading might involve doing 5 repetitions as fast as possible using a weight that is half the maximum load you can lift. You can gauge your progress by timing how fast you can perform the repetitions.
Training with a kettlebell an iron ball with a handle is a type of speed loading. Kettlebell training is highly ballistic, meaning that many exercises involve fast, pendulum-type motions, extreme decelerations, and high-speed eccentric muscle contractions. Kettlebell swings require dynamic concentric muscle contractions during the upward phase of the exercise followed by high-speed eccentric contractions to control the movement when returning to the starting position. Kettlebell training is very popular around the world, but more research is needed to better understand its effects on strength, power, and fitness.
• Isokinetic exercise involves exerting force at a constant speed against an equal force exerted by a special strength training machine. The isokinetic machine provides variable resistance at different points in the joint’s range of motion, matching the effort applied by the individual while keeping the speed of the movement constant. Isokinetic exercises are excellent for building strength and endurance.
Kettlebells are growing in popularity. They provide a fast, effective workout when used properly
Comparing Static and Dynamic Exercise Static exercises require no equipment, so they can be done virtually anywhere. They build strength rapidly and are useful for rehabilitating injured joints and stabilizing joints in the shoulder and spine. On the other hand, they have to be performed at several different angles for each joint to improve strength throughout its entire range of motion. Dynamic exercises can be performed without equipment (calisthenics) or with equipment (weight training). Not only are they excellent for building muscular strength and endurance, but they also tend to build strength through a joint’s full range of motion. Most people develop muscular strength and endurance using dynamic exercises. Ultimately, however, the type of exercise a person chooses depends on individual goals, preferences, and access to equipment.
