Friday, September 16, 2016

Plyometrics

Athletes are required to generate explosive power when performing athletic based movements. These movements in a competitive scenario would require changing of direction, accelerations, jumping and sprinting. Plyometric was created to improve this generation of power. The credit goes to the Russian Scientist Yuri Verkhoshansky for creating Plyometrics, he developed the protocol to imitate and improve the explosive aspect of athletic training. As per his observation, in jumping and running the lower limbs have to absorb and react to ground reaction forces that were very high (4).
In simpler terms, Plyometric training adapts the muscles to provide the maximum force in a very short period of time. This is achieved by increasing the activation of a motor unit and in the maximum number of motor unit activation (4).

Technical aspect of Plyometrics
Any movement is executed by the contraction of muscle, the contraction can be further divided into an eccentric contraction where the lengthening of the muscle against resistance takes place and a concentric contraction is when the muscle shortens against resistance.
For a plyometric based activity we can divide the movement into three phases
1.    Eccentric contraction
2.    Amortization
3.    Concentric contraction
For instance, depth jump (See Figure. 1) was created to duplicate the explosive activity in a controlled, measurable environment. The first phase is initiated when an athlete jumps from a platform on to the ground. The powerful muscles of the leg extensors experience a certain amount of ground reaction forces (shock). The eccentric phase is accentuated in the landing where the muscle is forcibly contracted. The amortization phase is the phase between the landing and the jumping. This phase is the most important phase and needs to be short. If an athlete spends a longer time in the amortization phase there is a greater loss of stored energy. The final phase is the concentric phase, where the stored energy is combined with a voluntary contraction to ensue the next movement (3).
depthjump.jpg
Figure.1

How of the workout
Creating a plyometric program requires one to focus on increasing power. Power can be increased by increasing strength, speed or both the variables together simultaneously. Hence, while designing a program we need to measure the intensity this can be achieved by monitoring the foot strikes or touches (1). Since, the program is executed with maximal effort or speed the duration would be shorter in comparison to a conventional strength training program. Athletes engaging in a plyometric program needs to have met certain strength training protocols. Normally, a strength and conditioning coach administers certain battery of test before implementing a plyometric program for an athlete. However, it is advisable that the athlete should have certain amount of strength training experience or is strong enough to squat, deadlift 1.5 – 2 times their body weight.

What is the workout (4)
Examples
1.    Marching
2.    Skipping
3.    Side hops
4.    Forward and backward hops
5.    Jumping in place
6.    Multiple hops
7.    Footwork/cone drills
8.    Box/depth jumps

 Safety measures
1.    Surface for plyometric need to have shock absorbing qualities.
2.    Rest and recovery is important in any training scenario.
3.    It’s a sport specific workout that is performance oriented
4.    Right footwear that could provide adequate support and stability

Is Plyometrics required for the general population?
As a fitness professional, we designed program in resistance training based on specificity for the general population. This is based on the belief that exercise should replicate movements that are executed on a daily basis. A sedentary individual entering a gym needs to build on the base strength, where he gets stronger, fitter and leaner by increasing the poundage, volume or the speed in their major lifts. This is done by providing the individual with a program that focuses on compound movements and minimises the chance of injury. It is very rare for us in our daily lifestyle to execute a movement that requires explosiveness, power. So a very specific plyometric program is not advisable for an individual whose only goal is to get fitter or leaner. However, certain low intensity based jumps, skipping and hopping can be included in a program for a specific time frame. Further, it is advisable that any plyometric program should be designed by a strength and conditioning coach, after taking into consideration the fitness, strength levels of the individuals or the group. Another shortcoming that is observed in most commercial gyms is the absence of plyometric based equipments and infrastructure.

References
1.    LaKeysha, S, McClenton, L.E.B., Jared W.C. & Kerseey, R,D. (2008). The Effect of Short Term Vertimax Vs Depth Jump Training on Vertical Jump Performance. J. Strength Cond Res 22: 321-325, 2008.
2.    Lundin, P. (1987). Plyometrics Training Loads For Youths and Beginners. Track Coach
3.    Read, M.M. & Cisar. C. The Influence of Varied Rest Interval Lengths on Depth Jump Performance. (2001). J. Strength Cond15: 279-283, 2001.
4.    NSCA Position Statement. (1993). Explosive/Plyometric Exercises. National Strength and Conditioning Association Journal. 15(3):16.

Frank A. Mapranny,
Training Director,

YFC 

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