chapter

14Warm-Upand Stretching

Chapter Objectives • Identify the benefits and components of a preexercise

warm-up.• Assess the suitability of performing stretching

exercises for a warm-up.• Identify factors that affect flexibility.• Describe flexibility exercises that take advantage of

proprioceptive neuromuscular facilitation.• Explain the mechanisms that cause the muscular

inhibition that improves the stretch.• Select and apply appropriate static and dynamic

stretching methods.

Warm-Up • Warming up can have the following positive

impacts on performance:– Faster muscle contraction and relaxation of both agonist

and antagonist muscles– Improvements in the rate of force development and

reaction time– Improvements in muscle strength and power– Lowered viscous resistance in muscles– Improved oxygen delivery due to the Bohr effect whereby

higher temperatures facilitate oxygen release from hemoglobin and myoglobin

– Increased blood flow to active muscles– Enhanced metabolic reactions– An increased psychological preparedness for performance

Warm-Up

• Components of a Warm-Up– A general warm-up period may consist of 5 to 10

minutes of lower intensity aerobic exercise, such as jogging or skipping.

– A specific warm-up period incorporates movements similar to the movements of the athlete’s sport. It involves 8 to 12 minutes of dynamic stretching focusing on movements that work through the range of motion required for the sport.

Key Point

• The warm-up is an integral part of the training session. Strength and conditioning professionals should plan warm-ups incorporating short-, medium-, and long-term considerations that will contribute to the overall development of the athlete.

Warm-Up

• RAMP protocol:– Raise: Elevate body temperature, heart rate,

respiration rate, blood flow, and joint fluid viscosity via low-intensity activities that simulate the movement patterns of the upcoming activity.

– Activate and Mobilize: Actively move through a range of motion.

– Potentiate: Perform sport-specific activities that progress in intensity until the athlete is performing at the intensity required for the subsequent competition or training session.

Dynamic Stretching During Warm-Up• Research suggests dynamic stretching is the

preferred option for stretching during warm-up.• Consider the range of motion and stretch-shortening

cycle requirements of the sport when designing a warm-up.Lunge With Twist Walking Knee Lift Walking Side Lunge

Flexibility

• Flexibility is a measure of range of motion (ROM) and has static and dynamic compo-nents.

• Static flexibility is the range of possible movement about a joint and its surrounding muscles during a passive movement.

• Dynamic flexibility refers to the available ROM during active movements and therefore requires voluntary muscular actions.

Flexibility

• Factors Affecting Flexibility– Joint Structure

• Structure determines the joint’s range of motion.– Age and Sex

• Older people tend to be less flexible than younger people; females tend to be more flexible than males.

– Connective Tissue• Elasticity and plasticity of connective tissues affect

ROM.

Flexibility (continued)

• Factors affecting flexibility– Stretch tolerance

• The ability of an athlete to tolerate the discomfort of stretching.

– Neural control• Range of motion is controlled by the central and

peripheral nervous system, including both afferent and efferent mechanisms.

(continued)

Flexibility

• Factors Affecting Flexibility– Resistance Training

• Exercise through a full ROM and develop both agonist and antagonist muscles to prevent loss of ROM.

– Muscle Bulk• Large muscles may impede joint movement.

– Activity Level• An active person tends to be more flexible than an

inactive one, but activity alone will not improve flexibility.

Flexibility

• Frequency, Duration, and Intensity of Stretching– Acute effects of stretching on ROM are transient;

for longer-lasting effects a stretching program is required.

– Minimum of twice a week for at least 5 weeks– Individual stretches should be held to the point of

mild discomfort, but not pain, for at least 15-30 sec.

Flexibility

• When Should an Athlete Stretch?– Following practice and competition

• Post-practice stretching facilitates ROM improvements because of increased muscle temperature.

• Stretching should be performed within 5 to 10 minutes after practice.

• Post-practice stretching may also decrease muscle soreness although the evidence on this is ambiguous.

Flexibility• When Should an Athlete Stretch?

– As a separate session• If increased levels of flexibility are required, additional

stretching sessions may be needed.• In this case, stretching should be preceded by a

thorough warm-up to allow for the increase in muscle temperature necessary for effective stretching.

• This type of session can be especially useful as a recovery session on the day after a competition.

• For longer-lasting effects, a daily stretching program is required.

• Stretching should be preceded by a thorough warm-up to allow for the increase in muscle temperature

Can stretching Reduce Injury Risks and Enhance Athletic Performance?

• There are data that show that stretching can both enhance and hinder performance.

– Probably depends on the sport/activity and the amount of initial flexibility a person has.

– Excessive flexibility decreases stability, while insufficient flexibility decreases ROM and may hinder normal movement patterns (both too much and too little can cause problems).

• For example, both excessive ER & inadequate IR in the throwing arm of a pitcher increases the risk of internal impingement. However, a pitcher with inadequate ER in the throwing shoulder (normal is approx 120-130 deg) will not be able to throw hard & performance may decrease.

Can stretching Reduce Injury Risks and Enhance Athletic Performance?

• Although stretching helps warm up the neuromuscular system, a general warm-up (e.g., 5 min walk on a treadmill) may be even more effective in warming up muscle tissue.

– Both muscle and nerves function better when warm– Warm muscles are less likely to be injured compared to cold

muscles• Stretching has not conclusively been shown to result

in either a decrease or increase in injuries rates

Proprioceptors and Stretching • Stretch reflex and reciprocal

inhibition– A stretch reflex occurs when

muscle spindles in the agonist (quadriceps in the example shown) are stimulated due to a rapid stretch of the agonist, causing the agonist to contract.

– Reciprocal inhibition occurs by stimulation of an inhibitory interneuron that inhibits the antagonist (hamstrings in the example shown), promoting relaxation of the antagonist.

– By reciprocal inhibition, when an agonist contracts, the antagonist relaxes.

Proprioceptors and Stretching

• Autogenic inhibition– Autogenic inhibition

occurs when high tension in the agonist (quadriceps in the example shown)stimulates golgi tendon organs in the tendon of the agonist, causing relaxation in the agonist due to stimulation of an inhibitory interneuron that inhibits the agonist.

Types of Stretching• Static Stretch

– A static stretch is slow and constant, with the end position held for 30 seconds.

• Ballistic Stretch– A ballistic stretch typically involves active muscular effort

and uses a bouncing-type movement in which the end position is not held (which may evoke the stretch reflex).

• Dynamic Stretch– A dynamic stretch is a type of functionally based

stretching exercise that uses sport-specific movements to prepare the body for activity.

• Proprioceptive Neuromuscular Facilitation (PNF)– A neuromuscular inhibition technique which stimulates

proprioceptors in a manner that results in muscle lengthening and increased ROM (the muscle being stretched is arbitrarily referred to as the antagonist).

Static Stretching

• Muscle slowly elongated beyond point of tissue resistance, but individual should be comfortable, relaxed, & pain-free.

• 15s, 30s, and 60s stretch durations have all demonstrated significant increases in muscle elongation.

– In younger individuals, no differences in muscle elongation between 30s or 60s durations, but both more effective than 15s duration.

– In individuals > 65 y.o., 60s durations produced greater ROM gains that persisted longer compared to 15s or 30s durations.

• Repeat stretch at least 1-2 times for maximum improvement.• Progressively increase stretch as muscle tension decreases.• Safer than ballistic stretching, with less tissue trauma and

post-exercise soreness.

Precautions for Static Stretching

• Decrease stretch intensity if you experience pain, radiating symptoms, or loss of sensation.

• Use caution when stretching a hypermobile joint.• Avoid combination movements that involve the

spine (e.g., extension with lateral flexion; flexion with rotation).

• Stabilizing muscles should be active to protect other joints and prevent unwanted movements.

Static Stretching Exercises

Look Right and Left

Flexion and Extension

Straight Arms Behind Back

Seated Lean-Back

Behind-Neck Stretch (Chicken Wing)

Cross Arm in Front of Chest

Arms Straight Up Above Head (Pillar)

Spinal Twist (Pretzel)

Semi–Leg Straddle

Forward Lunge (Fencer)

Supine Knee Flex

Side Bend With Straight Arms

Side Bend With Bent Arm

Side Quadriceps Stretch

Sitting Toe Touch

Semistraddle (Figure Four)

Straddle (Spread Eagle)

Butterfly

Wall Stretch

Step Stretch

Guidelines for Dynamic Stretching

• Carry out 5 to 10 repetitions for each movement, either in place or over a given distance.

• Progressively increase the ROM on each repetition, but control the movement throughout.

• Increase the speed of motion on subsequent sets where appropriate.

• Actively control muscular actions as you move through the ROM.

• Maintain good form and technique throughout

Dynamic Stretching Exercises

Arm Swings

Inchworm

Lunge Walk

Lunge With Overhead Side Reach

Walking Knee Lift

Forward Lunge With Elbow to Instep

Heel-to-Toe Walk

Walking Over and Under

Walking Over and Under (continued)

Inverted Hamstring Stretch

(continued)

Inverted Hamstring Stretch (continued)

Straight-Leg March

Spiderman Crawl

Figures 13.3, 13.4, and 13.5

a b c

PNF (Hold-Relax Technique)

• a) Initial passive prestretch (10-15 s) of antagonist (hamstrings in example shown)

• b) Isometric muscle action of antagonist (6 s) – autogenic inhibition

• c) Longer passive stretch of antagonist (30 s) with increased ROM.

• Repeat technique1-2 times.

Figures 13.6, 13.7, and 13.8PNF (Contract-Relax Technique)

• a) Initial passive prestretch (10-15 s) of antagonist (hamstrings in example shown)

• b) Concentric muscle action of antagonist through full ROM (6 s) – autogenic inhibition

• c) Longer passive stretch of antagonist (30 s) with increased ROM.

• Repeat 1-2 times.

Figures 13.3, 13.4, and 13.5

a b c

PNF (Hold-Relax With Agonist Contraction Technique)

• a) Initial passive prestretch (10-15 s) of antagonist (hamstrings in example shown)

• b) Isometric muscle action of antagonist (6 s) – autogenic inhibition

• c) Both a longer passive stretch of antagonist (30 s) AND concentric or isometric action of agonist (hip flexors in example shown) used to increase the stretch with increased ROM – autogenic inhibition and reciprocal inhibition.

• Repeat technique1-2 times.

c

Key Points

• The hold-relax with agonist contraction is the most effective PNF stretching technique due to facilitation via both reciprocal inhibition and autogenic inhibition.

• Muscle stretching is also occurring during PNF stretching techniques, especially during hold-relax with agonist contraction (both agonist and antagonist are strengthened).

Figures 13.12 and 13.13Common Partner PNF Stretching

(Hamstrings PNF Shown Previously)Calves Chest

GroinQuadriceps/Hip Flexors

Shoulders