NASM essentials of sports performance training
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NASM essentials of sports performance training

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(B) Hip flexors. (continued )
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Dynamic stretching is the use of a muscle\u2019s own force production and the body\u2019s momentum to take a joint through the
full available range of motion (1,22) (Fig. 4.19).
FIGURE 4.18 (Continued ) (C) Bicep femoris. (D) Piriformis.
FIGURE 4.19 Dynamic stretches. (A) Lunge with rotation. (B) Prisoner squat. (C) Push-up with rotation. (continued )
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FIGURE 4.19 (Continued ) (D) Medicine ball rotation. (E) Medicine ball lift and chop. (F) Front lunge with reach. (G) Side
lunge with reach. (H) Turning lunge with reach. (I) Tube walking. (continued )
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The goal of any flexibility routine is to create multiplanar soft-tissue extensibility that is
controlled by the CNS. Though there are many types of flexibility training, no single method
can improve every flexibility deficit. The best flexibility program follows the integrated flexibil-
ity continuum.
When it comes to discussing flexibility, opinions, theories, and applications vary from one
professional to another. However, flexibility is a general term and one needs to be specific as to
the type of flexibility being discussed. 
To clarify current research, static stretching has been the subject of various studies that have
helped to define the current thoughts behind the role of stretching in increasing range of motion,
strength, and performance. 
Flexibility has been the subject of debate for several decades and a lack of consensus allows re-
searchers to continue to study the effects, duration, and methodologies behind stretching while
practitioners struggle to recommend the ideal static flexibility program. To date, this subject
might be one of the most profusely studied topics in fitness and sports medicine. Many believe
FIGURE 4.19 (Continued ) (J) Scorpion. (K) Iron cross. (L) Russian twist. (M) Single-leg squat touchdown. (N) Leg swings,
front to back. (O) Leg swings, side to side.
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static stretching provides the benefit of increased range of motion and decreased muscle stiffness.
The debate seems to be centered on the basic prescription such as the type of stretch (e.g., static
stretching or PNF/neuromuscular stretching), the duration of the stretch required to increase
range of motion, and the mechanism of the adaptation to stretching (how stretching increases
range of motion). Researchers continue to determine what form of stretching creates the greatest
increase in range of motion around a joint, the mechanics of stretching, along with the duration
of a stretch required to see a significant change in range of motion.
Evidence-Based Research on Flexibility
Training\u2019s Effects on Range of Motion
According to several studies, both static stretching and PNF/NMS have shown positive effects on
improving range of motion; however, PNF/NMS stretching created the largest gains in range of
motion. Sady et al. (65) found PNF/NMS stretching superior to all types of flexibility when used
to increase range of motion of the trunk, shoulder, and hamstring complex (65). Whether
PNF/NMS was performed as either the contract-relax-contract technique or the hold-relax-con-
tract technique, significant improvements in range of motion were seen over a 6-week span when
compared to traditional static stretching (66). In fact, when tested head-to-head against a home
program of static stretching, PNF/NMS stretching reigned supreme; a self-applied PNF stretching
program using a contract-relax-contract method increased range of motion more than self-
applied static stretching (67).
A full description of the mechanism of action about the adaptations to a stretching program
will be unveiled in future research. Current theories equate increased range of motion to struc-
tural changes, changes in stretch sensation or both. Some theorize that structural changes, such
as decreased stiffness of the muscle tendon unit and passive resistive force, take place when per-
forming static stretching (61,68), whereas others hypothesize that the muscle structure does not
actually change, but a change in the stretch sensation leads to increases in range of motion (69).
The greater stretch tolerance might lead to increased range of motion around a joint (69).
While various stretching protocols exist, researchers have begun to understand the effect of
stretching duration on increasing ranges of motion. In an important study by Bandy et al. (70),
the duration of holding a stretch was measured against shorter or longer static stretching proto-
cols for the hamstring complex. Thirty seconds of holding a single stretch, once a day, 5 days a
week for 6 weeks resulted in increased range of motion at a joint (70). However, in contrast to
Bandy\u2019s findings, Bazett-Jones et al. (71) found that a static stretching protocol (using 3 sets of
30-second holds) showed no effects on increasing range of motion of the hamstring complex and
quadriceps as did the research of Youdas et al. (72), which showed no significant changes in
range of motion in the gastrocnemius after implementing a 6-week stretching regimen (30-sec-
ond duration stretches, performed once a day, 5 days a week) (81). Given the differences in re-
search results, it is important to analyze a few different factors that may affect the relationship be-
tween static stretching and range of motion.
NASM\u2019s Position on the Use of Static
Stretching to Enhance ROM
While more research must be done to understand some of the underlying factors on how stretch-
ing increases range of motion, there are a few determinants that NASM uses to understand the
role of static stretching on increasing range of motion. First is the determination of muscle im-
balances that may affect range of motion. When testing the range of motion of the hamstring
complex, stretching the opposite muscles (the quadriceps) increases range of motion at the hips
(73). When the quadriceps are tight, an anterior pelvic tilt of the hips is created, effectively increas-
ing the length of the hamstring complex that decreases range of motion for hip flexion. Flexibility
and range of motion require a thorough and integrated assessment process to evaluate all aspects
or barriers to range of motion and not an isolated look at a singular muscle. A limited range of
motion could be secondary to an issue at a neighboring joint. Second, the implementation of the
method may be specific to certain muscles. When looking at the contrasting studies of Bandy
et al. versus Youdas et al., Youdas et al. implemented an exact replica of the methodology of
Bandy et al., but performed the stretches on the gastrocnemius muscle focusing on dorsiflexion
range of motion. Although Youdas et al. found that the stretching regimen did not produce the
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Static stretching has become commonplace in most exercise and performance activities, usually
performed prior to and after the exercise or sporting activity. Historically, clinicians have used
static stretching to increase range of motion and decrease muscle stiffness that theoretically will
prevent injury and enhance performance through optimal neuromuscular efficiency (if proper
length-tension relationships exists around a joint). However, given the changes that static