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PLYOMETRIC TRAINING – THE POWER TO SUCCEED

by / Friday, 30 March 2018 / Published in Articles, Physical Therapy

INTRO TO PLYO

Energy is required to improve our bodies and the systems that work within them. A powerful way to add energy into a rehab program, bridge or workout program is through plyometric training. Plyometrics can also be called plyos, and they consist of powerful and fast movements. Plyos raise the force and speed of your muscle contractions, leading to higher explosive power needed in sports and even every day activities.

PEAK TORQUE VS POWER

The health of our muscles are typically divided into three categories known as strength, endurance and flexibility. Muscle strength can be divided into two main components. The first is peak torque, which is the amount of force that a muscle can produce. The second component of strength is power, known as the amount of force produced by the muscle over a period of time. Peak torque is improved using traditional resistance programs, with weights or other forms of resistance impeding a certain movement. Power is improved when the muscle exerts maximum force in a short interval of time, such as using explosive, quick movements and plyometrics. Power is also defined as a muscle’s rate of force development.

This concept is important. With athletic activity, a muscle’s strength capacity needs to be achieved within 0.25 seconds in order to perform well with explosive running and agility type movements. In day to day activities, strength capacity needs to be achieved within 0.5 seconds in order to perform movements such as walking or getting in and out of the car. Take a moment to understand this. Muscle can have a very high peak torque and produce high levels of force, but if it is unable to access that strength within 0.25 seconds for an athletic movement or within 0.5 seconds for normal activities, then the risk for injury substantially increases.

PLYOMETRICS EXPLORED

A plyometric exercise program should be a key part of any strength and conditioning program, performance enhancement program, or performance-based rehabilitation, as they assist in the development of the power (time component discussed above) needed both in sports and in activities of daily living.

Plyometrics consist of 3 phases:
1. Eccentric pre-stretch (loading) phase.
2. Amortization (coupling or time to rebound) phase.
3. Concentric shortening (rebound) phase.

Using jumping as an example, the eccentric pre-stretch phase occurs when a person squats down in preparation to jump. This causes a stretch in the muscle spindle of the muscle-tendon unit, stimulating components of the muscle and building potential kinetic energy inside the muscle. With respect to jumping, the amortization phase occurs when a person transitions from the preparatory squat to the explosive movement upward. This is the period of maximal storage of the potential kinetic energy discussed previously and is the key to effective and powerful plyometric exercise. The shorter the amortization phase, the more potential kinetic energy will be available for the next phase. The longer the amortization phase, the more energy will be wasted as heat. The concentric shortening phase is the last phase of the cycle. This occurs when the person in this example explodes upwards to reach maximum vertical jump height. This phase results from many interactions that utilize the elastic properties of the pre-stretched muscle. The blending of these three phases to perform a plyometric moment is used to enhance the muscle’s power performance.

Plyometric activities can be utilized in both the lower and upper extremities, with running, jumping, or throwing a ball as common examples. Nearly all sports and many activities of daily and work-related activities will include some form of plyometric activity. Due to the fact that so many functional activities require specific timing of force development in a muscle for proper performance, it is imperative that plyometrics be included in strengthening programs and appropriately in the later phases of rehabilitation.

PHYSICAL THERAPY AND TESTING

At Wright Physical Therapy, we use isokinetic testing to obtain specific information on both peak torque and rate of force development (Power) of muscle groups. Isokinetic testing uses specific equipment which allows for isolation of targeted muscles that govern the movement of specific joints. The test is always performed in comparison to the contralateral extremity, this allows for quantifiable assessment of deficits in the peak torque, power, and how their ratios correlate.

Isokinetic testing has been shown to produce reliable data as compared to simple manual muscle testing . This means that a group of muscles are tested against the manual resistance of the therapist. The strength is then graded on a scale from 0-5, 0 is the lowest and 5 being the highest level of strength. In the research, it shows that manual muscle testing alone can have up to a 30% error in its results as compared to Isokinetic testing.

Once the test results are obtained it allows for appropriate decisions on return to sport, work, and to daily activities of living. These test results also aide significantly in knowing when to begin plyometric activity and what stage of rehabilitation the patient is currently in.

PLYOMETRIC_TRAININGPerforming an Isokinetic test for muscle assessment alone is not enough. Dynamic Movement Assessments play a key role in the assessment to see how that strength is being used in functional and athletic movements. Based on these findings, we can then initiate an individualized plan of care that will help regain muscle strength (Peak Torque and Power), balance, and stability while reducing the risk for future injury.

CONCLUSION

There is a threshold of muscle strength that is necessary to be achieved within a specified period of time during athletic activity and normal day activities. If these levels of strength are not obtained in a timely manner it leads to poor body mechanics and performance which can result in preventable injury.

Isokinetic muscle testing can be performed to assess both a muscle’s peak torque and power which is the amount of force produced by the muscle over a period of time. Once assessed, a specific treatment plan that includes plyometrics can be formulated that is individualized to each person’s unique needs and activities performed throughout the day. This will both improve performance and reduce the risk of injury.
Please call us today at one of our clinic locations to schedule for treatment or referral.

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