Just as appropriate alignment and effective stabilization are fundamental components of muscle testing and goniometry as well as ROM and strengthening exercises, they are also essential elements of effective stretching.
Alignment
Proper alignment or positioning of the patient and the spe- cific muscles and joints to be stretched is necessary for patient comfort and stability during stretching. Alignment influences the amount of tension present in soft tissue and consequently affects the ROM available in joints. Align- ment of the muscles and joint to be stretched as well as the alignment of the trunk and adjacent joints must all be con- sidered. For example, to stretch the rectus femoris (a mus- cle that crosses two joints) effectively, as the knee is flexed and the hip extended, the lumbar spine and pelvis should be aligned in a neutral position. The pelvis should not tilt anteriorly nor should the low back hyperextend; the hip should not abduct or remain flexed (Fig. 4.8). When a
DETERMINANTS, TYPES,
AND
EFFECTS OF
STRETCHING
INTERVENTIONS
As with other forms of therapeutic exercise, such as strengthening exercises and endurance training, there are a number of essential elements that determine the effective- ness of stretching interventions. The elements (determi- nants) of stretching, all of which are interrelated, include
alignment and stabilization of the body during stretching;
the intensity (magnitude), duration, speed, frequency, and
mode of stretch; and the integration of neuromuscular inhi-
bition or facilitation and functional activities into stretching programs. By manipulating the determinants of stretching interventions, which are defined in Box 4.3, a therapist has many options from which to choose when designing stretching programs that are safe and effective and meet many patients’ needs, functional goals, and capabilities. Each of these determinants is discussed in this section of the chapter.
There are four broad categories of stretching exer- cises: static stretching, cyclic stretching, ballistic stretch- ing, and stretching techniques based on the principles of proprioceptive neuromuscular facilitation.19,35,44,72,165
Each of these approaches to stretching can be carried out in various manners—that is, manually or mechanically, passively or actively, and by a therapist or independently by a patient—giving rise to many terms that are used in the literature to describe stretching interventions. The stretching interventions listed in Box 4.4 are defined and discussed in this section.
Extensive evidence from numerous research studies has shown that stretching interventions can improve flexi-
BOX 4.3 Determinants of Stretching Interventions BOX 4.4 Types of Stretching
•Static stretching
•Cyclic/intermittent stretching
•Ballistic stretching
•Proprioceptive neuromuscular facilitation stretching pro- cedures (PNF stretching) •Manual stretching •Mechanical stretching •Self-stretching •Passive stretching •Active stretching
patient is self-stretching to increase shoulder flexion, the trunk should be erect, not slumped (Fig. 4.9B).
Stabilization
To achieve an effective stretch of a specific muscle or muscle group and associated periarticular structures, it is imperative to stabilize (fixate) either the proximal or distal attachment site of the muscle-tendon unit being elongated. Either site may be stabilized, but for manual stretching it is common for a therapist to stabilize the proximal attachment and move the distal segment, as shown in Figure 4.10A.
78 DETERMINANTS, TYPES AND EFFECTS OF STRETCHING INTERVENTIONS
FIGURE 4.8 (A) Correct alignment when stretching the rectus femoris: the lumbar spine, pelvis, and hip are held in a neutral position as the knee is flexed. (B) Incorrect position of the hip in flexion. In addition, avoid anterior pelvic tilt, hyperextension of the lumbar spine, and abduction of the hip.
FIGURE 4.9 (A) Correct alignment when stretching to increase shoulder flex- ion: the cervical and thoracic spine is erect. (B) Incorrect alignment: forward head and rounded spine.
FIGURE 4.10 (A) The proximal attachment (femur and pelvis) of the muscle being stretched (the quadriceps) is stabilized as the distal segment is moved to increase knee flexion.
For self-stretching procedures, a stationary object, such as a chair or a doorframe, or active muscle contrac- tions by the patient may provide stabilization of one seg- ment as the other segment moves. During self-stretching, it is often the distal attachment that is stabilized as the proxi- mal segment moves (Fig. 4.10B).
FIGURE 4.10 (B) During this self-stretch of the quadriceps, the distal seg- ment (tibia) is stabilized through the foot as the patient moves the proximal segment (femur) by lunging forward.
N O T E : Throughout this and later chapters, recommenda-
tions for appropriate alignment and positioning during stretching procedures are identified. If it is impossible for a patient to be placed in or assume the recommended postures because of discomfort, restrictions of motion of adjacent joints, inadequate neuromuscular control, or cardiopulmonary capacity, the therapist must critically analyze the situation to determine an alternative position.
Despite numerous studies, there continues to be a lack of agreement on the “ideal” combination of the duration of a single cycle and the number of repetitions of stretch that should be applied in a daily stretching program to achieve the greatest and most sustained stretch-induced gains in ROM. The duration of stretch must be put in context with other stretching parameters, including intensity, frequency, and mode of stretch. Key findings from several studies are summarized in Box 4.5 on the following page.
Numerous descriptors are used to differentiate between a long-duration versus a short-duration stretch. Terms such as static, sustained, maintained, and prolonged are all used to describe a long-duration stretch, whereas terms such as cyclic, intermittent, or ballistic are used to characterize a short-duration stretch. There is no specific time period assigned to any of these descriptors, nor is there a time frame that distinguishes a long-duration from a short-duration stretch.
Static Stretching
Static stretching*is a commonly used method of stretching
in which soft tissues are elongated just past the point of tissue resistance and then held in the lengthened position with a sustained stretch force over a period of time. Other terms used interchangeably are sustained, maintained, or prolonged stretching. The duration of static stretch is pre- determined prior to stretching or is based on the patient’s tolerance and response during the stretching procedure.
In research studies the term “static stretching” has been linked to durations of a single stretch cycle ranging from as few as 5 seconds to 5 minutes per repetition when either a manual stretch or self-stretching procedure is employed.†If a mechanical device provides the static
stretch, the time frame can range from almost an hour to several days or weeks.15,68,76,79,96,100,106(See additional
information on mechanical stretching later in this section.)
Focus on Evidence
In a systematic review of the literature (28 studies) on hamstring stretching,35a 30-second manual or self-
stretching procedure performed for one or more repetitions was the most frequently used duration per repetition of stretch in static stretching programs. A 30-second stretch per repetition was also identified as the median duration of stretch in a review of the literature of studies on calf muscle stretching.163
Static stretching is well accepted as an effective form of stretching to increase flexibility19,35,44,71,72and has been
considered a safer form of stretching than ballistic stretch- ing (described in the next section on speed of stretch) for many years.39Research has shown that tension created in
muscle during static stretching is approximately half that created during ballistic stretching.148This is consistent with
Stabilization of multiple segments of a patient’s body also helps maintain the proper alignment necessary for an effective stretch. For example, when stretching the iliop- soas, the pelvis and lumbar spine must maintain a neutral position as the hip is extended to avoid stress to the low back region. Sources of stabilization include manual con- tacts, body weight, or a firm surface such as a table, wall, or floor.