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Megan Pathoomvanh, Chase Feldbrugge, Lauren Welsch and Bonnie Van Lunen

Clinical Question:

Are posterior shoulder stretching programs effective in reducing posterior shoulder tightness, or tightness to the soft tissue of the shoulder, in overhead athletes?

Clinical Bottom Line:

In overhead athletes, there is high quality evidence to support the use of posterior shoulder stretching to reduce a commonly used measure of posterior shoulder tightness. All three studies1–3 reported an increase in shoulder internal rotation range of motion following implementation of posterior shoulder stretching.

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Marie A. Johanson, Megan Armstrong, Chris Hopkins, Meghan L. Keen, Michael Robinson and Scott Stephenson

Context:

Stretching exercises are commonly prescribed for patients and healthy individuals with limited extensibility of the gastrocnemius muscle.

Objective:

To determine if individuals demonstrate more dorsiflexion at the ankle/rear foot and less at the midfoot after a gastrocnemius-stretching program with the subtalar joint (STJ) positioned in supination compared with pronation.

Design:

Randomized controlled trial.

Setting:

Biomechanical laboratory.

Participants:

22 volunteers with current or recent history of lower-extremity cumulative trauma and gastrocnemius tightness (10 women and 4 men, mean age 28 y) randomly assigned to stretching groups with the STJ positioned in either pronation (n = 11) or supination (n = 11).

Intervention:

3-wk home gastrocnemius-stretching program using a template to place the subtalar joint in either a pronated or a supinated position.

Main Outcome Measures:

A 7-camera Vicon motion-analysis system measured ankle/rear-foot dorsiflexion and midfoot dorsiflexion of all participants during stretching with the STJ positioned in both pronation and supination before and after the 3-wk gastrocnemius-stretching program.

Results:

A 2-way mixed-model ANOVA revealed a significant interaction (P = .019). At posttest, the group who performed the 3-week stretching program with the STJ positioned in pronation demonstrated more increased ankle/rear-foot dorsiflexion when measured with the STJ in pronation than the group who performed the 3-wk stretching program with the STJ positioned in supination. No significant main effect of stretching group or interaction for dorsiflexion at the midfoot was detected (P = .755 and P = .820, respectively).

Conclusion:

After a 3-wk gastrocnemius-stretching program, when measuring dorsiflexion with the STJ positioned in supination, the participants who completed a 3-wk gastrocnemius stretching program with the STJ positioned in pronation showed more increased dorsiflexion at the ankle/rear foot than participants who completed the stretching program with the STJ positioned in supination.

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Pablo B. Costa, Eric D. Ryan, Trent J. Herda, Ashley A. Walter, Katherine M. Hoge and Joel T. Cramer

This study examined the acute effects of passive stretching on electromechanical delay (EMD), peak twitch force (PTF), rate of force development (RFD), and peak-to-peak M-wave (PPM) for the soleus muscle during evoked isometric plantar flexion muscle actions. Fourteen men (mean age ± SD = 21.2 ± 2.4 years; body mass = 80.0 ± 14.9 kg; height = 176.9 ± 7.2 cm) and 20 women (20.9 ± 2.5 years; 61.3 ± 8.9 kg; 165.3 ± 7.5 cm) volunteered for the study. Five single-square, supramaximal transcutaneous electrical stimuli (each separated by 5 s) were delivered to the tibial nerve before and after passive stretching. A time × gender interaction was observed for EMD, and the post hoc dependent-samples t tests indicated that EMD increased 4% for the women (p = .023), but not for the men (p = .191). There were no other stretching-related changes for PTF, RFD, or p-p M-wave for either the men or women (p > .05). These findings tentatively suggested that mechanical factors related to the stiffness of the muscle-tendon unit may contribute to the explanation for why stretching caused an acute increase in the EMD during evoked twitches in the women, but not in the men.

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Lawrence W. Judge, David Bellar, Kimberly J. Bodey, Bruce Craig, Michael Prichard and Elizabeth Wanless

The purpose of this study was to determine if NCAA Division I and III men’s basketball programs were in compliance with recommended pre- and post-activity stretching protocols. Questionnaires were sent to 500 NCAA Division I and Division III programs in the United States. Seventy-six coaches (75 males & 1 female) participated in the study. Chi-Square analysis (χ2(3,n=69) = 42.29, p≤0.001) indicated a greater combined percentage of static/pnf/ballistic stretches (10.14%, n=7) and combination of stretches (57.97%, n=40) than expected as compared to dynamic stretches (31.89%, n=22). Participants were asked during what period (pre- or post-activity) stretching should be emphasized. The results were significantly different from expected (χ2(4,n=76) = 129.28, p≤0.001), with a greater percentage of pre-activity stretches (26.31%, n=20) and both pre- and post-activity of stretches (60.52%, n=46) being reported as compared to post-activity stretches (13.15%, n=10). Some results seemed to be in conflict with current recommendations in the literature regarding pre-activity stretching practices.

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Mikael Scohier, Dominique De Jaeger and Benedicte Schepens

The purpose of this study was to mechanically evoke a triceps surae stretch reflex during the swing phase of running, to study its within-the-step phase dependency. Seven participants ran on a treadmill at 2.8 m·s−1 wearing an exoskeleton capable of evoking a sudden ankle dorsiflexion. We measured the electromyographic activity of the soleus, medial and lateral gastrocnemii just after the perturbation to evaluate the triceps surae stretch reflex. Similar perturbations were also delivered at rest. Our results showed that the stretch reflex was suppressed during the swing phase of running, except in late swing where a late reflex response was observed. At rest, all triceps surae muscles showed an early reflex response to stretch. Our findings suggest that the triceps surae short/medium-latency stretch reflex cannot be evoked during swing phase and thus cannot contribute to the control of the locomotor pattern after aperturbation during this phase.

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Allyson M. Carter, Stephen J. Kinzey, Linda F. Chitwood and Judith L Cole

Context:

Proprioceptive neuromuscular facilitation (PNF) is commonly used before competition to increase range of motion. It is not known how it changes muscle response to rapid length changes.

Objective:

To determine whether PNF alters hamstring muscle activity during response to rapid elongation.

Design:

2 X 2 factorial.

Setting:

Laboratory.

Participants:

Twenty-four women; means: 167.27 cm, 58.92 kg, 21.42 y, 18.41% body fat, 21.06 kg/m2 BMI.

intervention:

Measurements before and after either rest or PNF were compared.

Main Outcome Measures:

Average muscle activity immediately after a rapid and unexpected stretch, 3 times pretreatment and posttreatment, averaged into 2 pre-and post- measures.

Results:

PNF caused decreased activity in the biceps femoris during response to a sudden stretch (P = .04). No differences were found in semitendinosus activity (P = .35).

Conclusions:

Decreased muscle activity likely results from acute desensitization of the muscle spindle, which might increase risk of muscle and tendon injury.

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Gerrit Jan van Ingen Schenau, Maarten F. Bobbert and Arnold de Haan

This target article addresses the role of storage and reutilization of elastic energy in stretch-shortening cycles. It is argued that for discrete movements such as the vertical jump, elastic energy does not explain the work enhancement due to the prestretch. This enhancement seems to occur because the prestretch allows muscles to develop a high level of active state and force before starting to shorten. For cyclic movements in which stretch-shortening cycles occur repetitively, some authors have claimed that elastic energy enhances mechanical efficiency. In the current article it is demonstrated that this claim is often based on disputable concepts such as the efficiency of positive work or absolute work, and it is argued that elastic energy cannot affect mechanical efficiency simply because this energy is not related to the conversion of metabolic energy into mechanical energy. A comparison of work and efficiency measures obtained at different levels of organization reveals that there is in fact no decisive evidence to either support or reject the claim that the stretch-shortening cycle enhances muscle efficiency. These explorations lead to the conclusion that the body of knowledge about the mechanics and energetics of the stretch-shortening cycle is in fact quite lean. A major challenge is to bridge the gap between knowledge obtained at different levels of organization, with the ultimate purpose of understanding how the intrinsic properties of muscles manifest themselves under in-vivo-like conditions and how they are exploited in whole-body activities such as running. To achieve this purpose, a close cooperation is required between muscle physiologists and human movement scientists performing inverse and forward dynamic simulation studies of whole-body exercises.

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Nicole D. Harshbarger, Bradly L. Eppelheimer, Tamara C. Valovich McLeod and Cailee Welch McCarty

Clinical Scenario:

It has been suggested that posterior shoulder tightness is a common contributor to shoulder impingement in overhead-throwing athletes. The incidence of shoulder pain in the general population has been reported to be as high as 27%, and as many as 74% of the patients who were seen for shoulder issues had signs of impingement. Particularly regarding physically active adults, shoulder impingement is frequent among overhead-throwing athletes and may lead to lost participation in sport, as well as other injuries including labral pathologies. Therefore, finding an effective mechanism to reduce posterior shoulder tightness in overhead athletes is important and may help prevent impingement-type injuries. Typically, posterior shoulder tightness is identified by measuring horizontal humeral adduction; although another clinical measure that is commonly used is the bilateral measurement of glenohumeral internal-rotation (IR) range of motion (ROM). It is important to note, however, that the measurement of glenohumeral IR ROM specifically aims to identify glenohumeral IR ROM deficits (GIRD). Although GIRD is believed to be a leading contributor to posterior shoulder tightness, this measure alone may not capture the full spectrum of posterior shoulder tightness. While treatment interventions to correct any ROM deficits typically include a stretching protocol to help increase IR, joint mobilizations have been found to produce greater mobility of soft tissue and capsular joints. However, it is unclear whether the combination of both joint mobilizations and a stretching protocol will produce even larger gains of ROM that will have greater longevity for the patient suffering from posterior shoulder tightness.

Focused Clinical Question:

Does the use of joint mobilizations combined with a stretching protocol more effectively increase glenohumeral IR ROM in adult physically active individuals who participate in overhead sports and are suffering from posterior shoulder tightness, compared with a stretching protocol alone?

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Masatoshi Nakamura, Tome Ikezoe, Takahiro Tokugawa and Noriaki Ichihashi

Context:

Hold–relax stretching (HRS) and static stretching (SS) are commonly used to increase joint range of motion (ROM) and decrease muscle stiffness. However, whether there are differences between acute effects of HRS and SS on end ROM, passive torque, and muscle stiffness is unclear. In addition, any differences between the mechanisms by which HRS and SS lead to an increase in end ROM are unclear.

Objective:

To compare the acute effects of HRS and SS on the passive properties of the gastrocnemius muscle–tendon unit (MTU), end ROM, passive torque, and muscle stiffness in vivo and to investigate the factors involved in increasing end ROM.

Design:

Crossover experimental design.

Participants:

30 healthy men (21.7 ± 1.2 y) with no history of neuromuscular disease or musculoskeletal injury involving the lower limbs.

Intervention:

Both HRS and SS of 30 s were repeated 4 times, lasting a total of 2 min.

Main Outcome Measures:

End ROM, passive torque, and muscle stiffness were measured during passive ankle dorsiflexion using a dynamometer and ultrasonography before and immediately after HRS and SS.

Results:

The results showed that end ROM and passive torque at end ROM significantly increased immediately after both HRS and SS, whereas muscle stiffness significantly decreased. In addition, the percentage change in passive torque at end ROM on use of the HRS technique was significantly higher than that after use of the SS technique. However, the percentage change in muscle stiffness after SS was significantly higher than that with HRS.

Conclusion:

These results suggest that both HRS and SS can effectively decrease muscle stiffness of the gastrocnemius MTU and that HRS induces a change in the passive torque at end ROM—ie, sensory perception—rather than changing muscle stiffness.

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Yoshinobu Ohira, Tomoo Yoshinaga, Wataru Yasui, Makoto Ohara and Takato Tanaka

The effects of chronic stretching or shortening of the soleus muscle of adult rats during hindlimb suspension on muscle mass and contractile properties were studied. Rats suspended with the ankle joint immobilized in either a dorsiflexed (Susp-DF. soleus stretched), a plantarflexed position (Susp-PF, soleus shortened), or without immobilization (Susp-Free. soleus shortened) were compared with cage control rats. Suspension-related muscle atrophy was prevented in Susp-DF. The relative muscle weight in Susp-PF was also less than in cage control and Susp-DF. Both isometric maximum twitch tension (Pt) and maximum tetanic tension (Po) in the Susp-Free and Susp-PF were less than control. Both Pt and Po in Susp-DF were normal. The twitch time-to-peak tension and one-half relaxation time tended to be reduced by chronic shortening of the muscle. The rate of tension development during a twitch (dp/dt), expressed as g/s, of Susp-Free group was decreased, but that expressed as g/s/g Pt was greater than controls. That in Susp-DF was subnormal. The fatigue resistance in Susp-Free was normal but was reduced in Susp-DF and Susp-PF. These data suggest that the decreases in the rat soleus mass and maximum tension production and the shift toward a fast-twitch type following hindlimb suspension are prevented by chronic stretching of muscle, although detrimental effect was induced for the fatigue resistance.