Explosive Plyometric Training

Get Toned, Leaner and Stronger

By Michael J. Rudolph, Ph.D.

Plyometric training is more than simply jumping up and down to improve vertical leap performance. This form of training, when performed correctly, can induce tremendous improvements in muscle tone and shape that, when combined with intense resistance training, can potently improve overall fitness and make you leaner, tighter and stronger.

Plyometric training can be used to train most body parts, including the upper body, where there are some fantastic plyometric movements that will make you more sculpted, toned and shapelier— not to mention the plethora of well-established plyometric jumping movements that generate tremendous lower-body functional fitness. So, while many dismiss plyometric training as solely for the athlete, the ability of plyometric training to sculpt your body and make you stronger, especially when used in conjunction with weight training, makes it a great training modality for anyone trying to get into better shape.

Most Effective Exercises

The standard plyometric workout consists of five to six sets within the five- to eight-repetition range, and approximately 90 seconds of rest between each set. The most effective plyometric exercises typically utilize just your bodyweight with no additional resistance. Some of the more popular and effective plyometric movements include box jumps, squat jumps and plyometric push-ups— which are one of my favorite plyometric exercises that may be added as a finishing movement when you train chest, to improve muscle tone.

Correct Form Is Key

Like most training methods, plyometrics must be done correctly to be effective. With plyometric training, that means the movement must be performed very rapidly to efficiently stretch the trained muscle during the eccentric phase. In addition, the concentric contraction must instantaneously follow the eccentric phase.1

The quick stretch of the muscle tissue during the eccentric phase of plyometric training triggers certain sensors within muscle tissue known as proprioceptors that reflexively boost muscular contraction force during the concentric phase.2 One of the proprioceptors activated by rapid muscle stretching during plyometric training is the muscle spindle, which detects the quick elongation of the muscle and initiates muscular contraction to prevent further stretching and possible muscle damage.

The second proprioceptor influenced by plyometrics is the Golgi tendon organ (GTO), which typically prevents central nervous system (CNS) activation of muscular contraction, specifically when the muscle is contracting very forcefully to also prevent muscle damage. However, the quick lengthening of the muscle from plyometric training actually inhibits the GTO, which ultimately boosts CNS-activated muscular contraction during the concentric phase.2,3

Improve Muscle Tone

Enhanced muscular contraction during the concentric phase from plyometric work will conceivably contribute to improvements in muscle tone and strength on its own. However, the most powerful training effect from plyometric movements stems from the substantial increase in CNS-activated muscular contraction, which not only improves power but should also yield greater gains in lean body mass — as enhanced power production stresses the muscle tissue. In fact, several studies show that plyometric training effectively increases muscular contraction intensity due to an increase in neural recruitment of additional muscle fibers4,5, which improves lean body mass, muscle tone and strength6,7— thus validating the notion that increased power from plyometric training can improve overall fitness and pave the way for hypertrophic gains.

Become More Powerful

Because resistance exercise increases the size and contraction force of individual muscle fibers, while plyometric training primarily increases the quantity of muscle fibers contributing to muscular contraction, combining plyometrics with weight training should provide a synergistic increase in contractile forces by making each individual muscle fiber stronger— while simultaneously increasing the activation of these larger, more powerful muscle fibers, resulting in increases in strength. In fact, several studies have confirmed that plyometric training combined with weight training produced superior gains in muscle strength and power, relative to using either training method alone.8,9

A Complement to Weight Training

Despite the common belief that plyometric training only bolsters muscle strength and power but does not improve lean body mass, several studies have actually demonstrated that plyometric training induces considerable muscle hypertrophy, particularly when combined with lifting weights.

A study by Kubo et al.6 showed that 12 weeks of plyometric work induced a significant increase of five percent in muscle size in the lower leg, and this effect was similar to the muscle growth stimulated by a 12-week weight-training program. A second study10 reported that combining plyometrics with resistance training generates a large increase in fast-twitch muscle fiber size of approximately 20 percent within the upper leg.

Overall, the data reveals that plyometric training, alone or in combination with resistance training, can trigger muscle growth, and the increases in lean body mass associated with plyometric training appear to be enhanced when combined with intense weight training— making plyometrics a complementary approach to standard weight training.

Plyometrics for a Hormonal Jump

While testosterone is a hormone that is mainly associated with men, women produce testosterone also. In fact, it’s a very important hormone for women if they want to tone their bodies. Production of the so-called “male hormone” is notably lower in women than in men, so any natural method to increase testosterone should be of interest to fit women.

Testosterone plays a key role in stimulating improvements in lean body mass in response to resistance training. In order to see if combining resistance exercise with plyometric training, or complex training, might produce greater increases in lean body mass by boosting levels of the anabolic hormone testosterone, a study by Beaven et al.11compared the influence of combining plyometric training with weights on serum testosterone levels, relative to performing resistance training alone. The results of the study showed that subjects performing resistance training that involved heavy box squats followed by plyometric jump squats had the largest spike in serum testosterone levels of 13 percent. This hormonal response after the strength-plyometric bout suggests that this exercise sequence, resistance work followed by plyometrics, provides a superior anabolic environment that conceivably supports greater increases in lean body mass.

Combining resistance exercise with plyometric training will do more than increase lean body mass and improve muscle tone. The more lean mass your body carries, the faster you will burn fat. Muscle acts like a furnace, burning fat 24/7. Incorporating a strength-plyometric bout into your workout program will enable you to increase your lean body mass at an expedited rate, for a slimmer, toned and shapelier figure.

Improved Performance

There are essentially two major types of muscle fiber; slow-twitch and fast-twitch fibers, where the fast-twitch fiber contracts roughly four times faster than slow-twitch fibers12, giving the fast-twitch fiber a greater force-producing capacity. Several animal studies have shown that plyometric training can increase the amount of fast-twitch muscle fibers by actually transforming slow-twitch fibers into fast-twitch fibers.13,14,15 Another investigation by Malisoux et al.16 also found a significant increase in the proportion of fast-twitch muscle fibers in the lower leg muscles of humans after performing lower body plyometric training.

Collectively, the results of these studies show that plyometric training can increase the composition of fast-twitch muscle fibers, which likely increases strength and power because of the fibers’ greater force-producing capabilities, representing an additional performance-enhancing effect associated with plyometric training.

The use of plyometric training, especially when combined with resistance work, potently enhances performance for enhanced function in the gym— ultimately promoting greater increases in lean body mass for a more toned and sculpted, leaner, shapelier body. So, forget the false notion that plyometric training is just for the athlete. It’s for any woman who wants to get in better shape, get toned and become stronger.

References:

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13. Pousson M, Perot C and Goubel F. Stiffness changes and fibre type transitions in rat soleus muscle produced by jumping training. Pflugers Arch 1991;419, 127-130.
14. Almeida-Silveira MI, Perot C, et al. Effects of stretch-shortening cycle training on mechanical properties and fibre type transition in the rat soleus muscle. Pflugers Arch 1994;427, 289-294.
15. Watt PW, Kelly FJ, et al. Exercise-induced morphological and biochemical changes in skeletal muscles of the rat. J Appl Physiol Respir Environ Exerc Physiol 1982;53, 1144-1151.
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