Effects of Plyometric Training on Sports

Effects of Plyometric

Training on Sports

Performance

Mark A. Booth, MA

1

and Rhonda Orr, PhD

2

1

Department of Exercise and Sports Science, University of Sydney, Sydney, Australia; and

2

Department of Exercise

and Sports Science, University of Sydney, Sydney, Australia

ABSTRACT

PLYOMETRIC TRAINING IS A

SERIES OF EXPLOSIVE BODY

WEIGHT RESISTANCE EXERCISES

USING THE STRETCH-

SHORTENING CYCLE OF THE

MUSCLE FIBER TO ENHANCE

PHYSICAL CAPACITIES SUCH AS

SPEED, STRENGTH, AND POWER.

THESE PHYSIOLOGIC MEASURES

TRANSLATE TO IMPROVED PER-

FORMANCE IN MANY SPORTS,

INCLUDING COURT-BASED

SPORTS, FIELD SPORTS, AND

WATER SPORTS. PERFORMANCE

ENHANCEMENTS RESULTING

FROM PLYOMETRIC TRAINING,

INCLUDE IMPROVED SPRINT TIMES

OVER DISTANCES RANGING FROM

5 TO 40 M, MAXIMAL MUSCLE

STRENGTH AND POWER, AND

INJURY PREVENTION MEASURES

SUCH AS IMPROVED LANDING

MECHANICS, DECREASED

GROUND REACTION FORCES,

AND IMPROVED HAMSTRING TO

QUADRICEPS RATIOS. THE OPTI-

MAL DOSE FOR ATHLETIC EN-

HANCEMENTS HAS NOT BEEN

CONSISTENTLY IDENTIFIED.

INTRODUCTION

Plyometric training (PT) is a cate–

gory of explosive body weight

resistance exercises which focuses

on exploiting the additional force

output of the stretch reflex of a muscle

to increase speed and power. A period

of rapid concentric contraction in the

muscle after a rapid eccentric length-

ening of the muscle fiber under load

enhances the force generated by the

muscle. The stretch-shortening cycle

(SSC) captures the energy of the

stretched muscle in its elastic compo-

nents and augments the next concen-

tric contraction provided it is rapidly

executed (73). This recoil effect can

enhance physiological qualities indica-

tive of improved sports performance

(speed, strength, and power) when har-

nessed and trained correctly.

An array of field (3), court (30), and

individual (2) sports use plyometric ex-

ercises. Correspondingly, the mode of

exercises are wide and diverse ranging

from double-leg, single-leg, in place,

etc. (21,58,79). These exercises are

not however limited to the lower

extremities as upper body exercises

(e.g., plyometric push-ups, chops, and

medicine ball exercises) are commonly

used for throwing sports (49).

PT is explosive in nature, therefore accu-

rate measurement of performance is vital

to detect significant worthwhile changes.

It is measured in a number of ways. Most

commonly, force plate measures (con-

tact time, ground reaction forces, take-

off velocity) (12,15,22,77) and electromy-

ography (16,22) to evaluate muscle

activation patterns, are used to assess per-

formance with plyometric exercise. Rel-

ative measures such as reactive strength

indices (14) are also used when other

methods are not possible, too expensive

or impractical.

The purpose of this article is to review

the existing literature on plyometric

training and its training effects as they

relate to a wide range of sports and

their performance indicators. In doing

so, it aims to provide practical guide–

lines for safe and effective program-

ming within a variety of sports for

performance enhancement and injury

prevention programs.

PHYSIOLOGICAL ADAPTATIONS

PT elicits a variety of physiological

adaptations, both structural and neural.

Changes in muscle size and/or archi-

tecture are common (52), whereas re–

ductions in fat mass are not usually

seen (24). Traditional resistance train-

ing (RT) elicits similar training adapta-

tions. Typically RT uses higher training

volumes and allows for more concen-

trated eccentric loading. It therefore

makes sense to combine RT and PT

when programming for performance

enhancement to maximize these train-

ing adaptations. Vissing et al. com-

pared RT and PT programs over

a 12-week period. They observed

increased quadriceps, hamstring, and

adductor whole-muscle cross-sectional

area (CSA) by 7 and 10%, respectively,

whereas total muscle size increased

KEY WORDS:

jump performance; strength; power; speed;

explosive exercise

VOLUME 38 | NUMBER 1 | FEBRUARY 2016 Copyright ÓNational Strength and Conditioning Association

30

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both with PT and RT (66). A study by

Chelly et al. (7) found increases in thigh

muscle volume were not accompanied

by change in leg muscle volume and

mean thigh CSA with PT.

More common structural changes

relate to changes in the mechanical

characteristics of the muscle-tendon

complex and single-fiber mechanics

(52). Increases in single muscle fiber di-

ameters of 10% in type IIa, 11% in type I,

and 15% in hybrid type IIa/x fibers have

been reported (37). The most com–

monly examined area of structural

change from PT involves analysis of

the plantar flexor tendon responses

such as stiffness (25,39,49,78), transmis-

sion of force (39), and CSA (39,45).

Comparisons of these factors between

traditional RT and PT have shown that

changes in jump performance relate to

changes in the MTC (71). However,

Foure et al. observed no change in joint

stiffness (18), whereas King et al.

observed increased joint stiffness (31).

This presents conflicting outcomes as

a result of PT. Interestingly, Kubo et al.

changes in stiffness observed in the gas–

trocnemius tendon complex or ankle

joint itself (19).

The gastrocnemius muscle did how-

ever exhibit changes in stiffness of

133% after 14 weeks PT training com-

pared with the control group. The PT

group demonstrated an improvement

in squat jump (SJ) and reactive jumps

of 117 and 119%, respectively (20).

The physiological adaptations of neu-

romuscular function to PT include

increased neural drive to agonist

muscles and changes in muscle activa-

tion strategies related to the SSC (39).

Female, high school volleyball players

recorded increases in peak hamstring

torques (44% dominant side/21% non-

dominant) and decreases in peak land-

ing forces in conjunction with

a corresponding 10% increase in verti-

cal jump (VJ) height (25). In addition,

Hewett et al. observed an increase in

hamstring to quadriceps ratios peak

muscle torque ratios of 26% dominant

side, 13% non-dominant side. It is likely

that these improvements in peak tor-

a concurrent increase in delayed onset

muscle soreness over the first 48 hours

after training (69). Immunological

measures of muscle damage in the

acute phase response have been mir-

rored along a similar timeline, by

reduction in jumping performance

(3,6) and rate of force development;

thus providing evidence that acute re–

sponses are primarily a consequence of

peripheral fatigue. Hence, adequate

recovery between bouts of PT is imper-

ative (13). By contrast, no differences in

acute hormonal, metabolic, or neuro-

muscular responses to PT, regardless

of repetition number, have been

reported (2).

PLYOMETRIC TRAINING EFFECTS

PT can elicit varied training effects de–

pending on the nature of the training

program. This is usually determined by

the desired sport-specific performance

enhancement. For example, a tennis

player would desire an improvement

in agility. Greater enhancements in

agility are seen using PT with a hori-

zontal component (59). A sprinter may