CHAPTER 7

PRINCIPLES OF INJURY PREVENTION
The sports medicine professional is concerned with the well being of the athlete
and generally assumes the responsibility for overseeing the total health care forthe athlete. Participation in sports places the athlete in a situation in which injury
is likely to occur. Fortunately, most injuries are not serious and lend themselves torapid rehabilitation, but the sports medicine professional must be capable of dealing
with any type of trauma or catastrophic injury.
A. Physical Conditioning

Physical conditioning is a key principle of injury prevention. Appropriate
conditioning programmes decrease the risk of injury, decrease the severity of an
injury should it occur, and can help prevent re-injury. Maximising the chance forsafe athletic performance requires adequate muscular strength and balance, power,endurance, neuromuscular coordination, joint ﬂexibility, cardiovascular endurance,and good body composition for sport.
Improving speciﬁc components of ﬁtness and conditioning reduces the risk ofinjuries. For example, strengthening the muscles of a joint helps reduce injuries tothe area; regular exercise can signiﬁcantly increase the strength of the ligaments
surrounding the knee and prevent knee injuries; development provides increased
strength that helps to stabilise joints; and improved movement skill is important inavoiding injury.
1. Strength
To improve muscle strength, stress must be progressive and gradually challenged
or placed under additional loading. A conditioning programme’s effects are speciﬁcto the type of stress applied. The SAID principle (Speciﬁc Adaptation to Imposed
Demands) states that as the body is placed under stress of varying intensities anddurations, it attempts to overcome the stress by adapting speciﬁcally to the imposeddemands. For example, muscles around a joint can be developed and conditioned
to provide optimal stabilisation of the joint. Likewise, when a muscle primarily
produces motion of a joint, proper conditioning can prevent the muscle fromundergoing an unwanted movement. The demands of a speciﬁc athletic event must
be a progressive stress applied in that athlete’s training.
Other components of strength conditioning that contribute to injury prevention
are the ability of the muscle to contract or exert force at an accelerated speed, andmuscular endurance, which allows the athlete to maintain an appropriate strength
level over a period of time.
2. Balance
Proprioceptive or kinesthetic sense through balance training enhances motorcontrol, which is needed to decrease the risk of injury or re-injury during practiceor competition. When injury to a joint or musculo-tendinous structure occurs,

CHAPTER 7, PRINCIPLES OF INJURY PREVENTION

somato-sensory information is altered, adversely affecting motor control. Hence,
rehabilitation should emphasise restoring the athlete’s balance strategies. This will
also decrease the risk of recurrent injury. The balance training tasks must be speciﬁcto the type of balance strategies required by the athlete’s event.
3. Flexibility
Efﬁcient performance requires a full range of motion, and adequate joint
ﬂexibility also decreases an athlete’s susceptibility to injury. Normal muscularlength-tension and adequate extensibility upon stretch aid in protecting the bodyfrom injury. The athlete’s entire body is able to work more efﬁciently and safely
after a period of warm-up, stretching, and skill-drills that are related to the athlete’sevent.
The warm-up period before practice or competition increases the body’s tissue
temperature prior to subjecting the musculo-tendinous structures to repeatedstretch and contraction. Connective tissue has visco-elastic properties, which allow
elongation of the tissue. Temperature has a signiﬁcant inﬂuence on the mechanicalbehaviour of connective tissue under tensile stretch. Higher temperatures at low
loads produce the greatest elongation with the least damage to connective tissue.
Increased connective tissue temperature also increases extensibility.
Optimal stretching occurs only when voluntary and reﬂex muscle resistance iseliminated. Ballistic stretching is not a favorable method because as the muscles
stretch rapidly, the intrafusal muscle spindles may be activated, causing a reﬂex
protective muscle contraction. Forceful ballistic stretching can also cause microtrauma of muscle ﬁbres.
4. Endurance
Cardiovascular endurance is also a factor in injury prevention. The cardiovascular and respiratory systems must be adequately conditioned to delay the onsetof fatigue. A fatigued athlete becomes vulnerable to injury when the nervous andmuscular systems are unable to respond adequately to an injury-producing situation.
B. Appropriate Training Methods

Ensuring proper, efﬁcient mechanics requires practice and effective coaching,including a systematic series of speciﬁc, repetitive, and progressive exercisesand drills. Faulty mechanics must be corrected and good fundamentals ingrained.
Exercises should include strength, relaxation, and ﬂexibility speciﬁcally geared tothe demands made on the body. (See Chapter 3, Part 1, Principles of Training.)
C. Rest and Recovery

Adequate sleep is important for general good mental and physical health,and becomes critical for recovery after intensive workouts. Chronic overexertionand fatigue can make the athlete susceptible to injury. (See Chapter 3, Part 2,Restoration, Recovery, and Overtraining.)

CHAPTER 7, PRINCIPLES OF INJURY PREVENTION

D. Muscle SorenessMuscular over-exertion may present as muscle soreness, muscle stiffness, andmuscle spasm. According to the muscle spasm hypothesis of muscle soreness,ischemia to the muscles releases pain substances from the muscle ﬁbres andstimulates the pain receptors, resulting in reﬂex spastic contractions and a continued
cycle of ischemia and pain. Stretching the muscles helps reduce the spasms andassociated pain. According to the tissue damage hypothesis, micro-tears occur andpain/soreness results from the nerve-endings being stimulated by muscle tissueswelling. Proper massage may aid in reducing tissue oedema and decreasing
accompanying muscle spasm. Ice applications or other forms of cryotherapy, andpool training, may facilitate the body’s healing response. Appropriate rest will allow
microscopic damage of the tissue to heal.
E. Appropriate Equipment

Shoes are the most critical piece of a track and ﬁeld athlete’s equipment andshould be individually and carefully selected. Proper ﬁtting shoes can mean thedifference between a low and a high risk of injury for a track and ﬁeld competitor.
Training in improperly ﬁtted shoes can result in chronic abnormal pressures to thefoot and cause stress injuries or structural deformities. Minor skin irritations such as
calluses and blisters can prove to be major hindrances to a runner. Improperly ﬁtted
or worn-out shoes can lead to mechanical disturbances and postural, muscular, andjoint dysfunctions.
The recent revolution in shoe research, design, and production has created aplethora of shoes from which to choose. However, the athlete’s shoes must meet
the biomechanical requirements and adapt to the demands of the individual’s event.
Shoe surveys can be useful in analysing the speciﬁc qualities of shock absorbency,foot control, and ﬂexibility, but athletes and coaches must be aware that new shoe
models have produced new injury syndromes.
Field event implements must meet use and safety speciﬁcations. Every memberof the sports team (coach, ofﬁcial, sports medicine personnel, athlete) must be awareof any hazardous ﬁeld situation where the ﬁeld event practices and competitions takeplace, and take action to assure the highest level of safety. (See Chapter 2, Part 4,Sports Rules and Athlete Safety.)
F. Psychological Factors

Athletes need to be psychologically prepared for practices and competition inorder to reduce the risk of injury. Research has demonstrated a positive relationshipbetween stressful life situations, especially those with high negative stress, andinjury occurrence. In understanding the stress-injury relationship, Nideffer (1983)
points out that muscle tension increases in response to stress. Increased tension in
the antagonist and agonist muscle groups results in reduced ﬂexibility and loss ofmotor coordination. Increased muscular tension also slows reaction time, which
reduces the athlete’s ability to respond.

CHAPTER 7, PRINCIPLES OF INJURY PREVENTION

Mental as well as physical fatigue can contribute to injury occurrence. The
attention factor—the ability to maintain a high level of concentration—requiresa large amount of energy; when combined with a rigorous training programme,
reduced attention can result. This may lead to slowed reaction times and loss ofneuromuscular coordination, thus increasing the potential for injury.
Athletes who have sustained an injury realise that they have to be mentally
ready for return to sport to avoid risking re-injury. The role of attentional focus andmuscular tension can be a major problem. Fear and/or worry about a second injury
can cause stress and increased muscular tension. Preliminary studies have addressed
hardiness (commitment, control, and challenge) of the athlete as a moderating factor
in the stress-injury relationship. Athletes who exhibit greater qualities of this trait
may be better able to control the attentional processing of information and in turn
reduce the potential for occurrence of a second injury.
G. Training in Extreme Conditions

Athletes and coaches should take into account the temperature and humidity
during training, and the need to acclimate after travel to a different, extreme
climate or altitude. Extreme heat and humidity, cold, and altitude can adversely
affect performance in many athletic events (see Chapter 11, Environmental Factors
Affecting Human Performance). To avoid dehydration and the fatigue that can occur
from inadequate ﬂuid replenishment, athletes must drink extra water, juices, andother ﬂuids (see Chapter 6, Part 1, Nutrition and Athlete Health). Athletes should
learn to drink before they feel thirsty—by the time an individual is aware of thirst,
they’ve lost 1% of their body weight; by 2% dehydration, the athlete may have
reduced his or her work capacity by 10–15%. Assuring adequate water, and juices
or sports drinks, helps keep the participant energised, focused, and better able toconcentrate.
The health and safety of the athlete must be the number one priority in any
practice or competitive situation. If unsafe climatic conditions occur, training should
be curtailed, and practice or competition times re-scheduled to allow the safest
environment for all participants (see Chapter 2, Part 4, Sports Rules and Athlete
Safety).
References

1.
2.
3.
4.

Clark, N. Fluids, Dehydration and Thirst Quenchers. Sports Nutrition Sports
Medicine Systems, Inc.
Irrgang, J., S. Whitney, and E. Cox. Balance and proprioceptive training forrehabilitation of the lower extremity. J. of Sport Rehab. 3:68-93, 1994.
Lamb, D. R. Physiology of Exercise, Responses and Adaptations (2nd edition),p. 322. New York: Macmillan, 1978.
Nideffer, R. M. The injured athlete: psychological factors in treatment. Orthop.
Clin. North Am. 14:373-385, 1983.

CHAPTER 7, PRINCIPLES OF INJURY PREVENTION

5.

6.

Pease, D. G. Psychologic factors of rehabilitation. In Physical Rehabilitationof the Injured Athlete (2nd edition), Andrews, J. R., and G. L. Harrelson (eds.),
pp.1-12. Philadelphia: W. B. Saunders Co., 1996.
Prentice, W. Arnheim’s Principles of Athletic Training (12th edition). Boston:
McGraw Hill, 2005.