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Asger Roer Pedersen, Peter William Stubbs and Jørgen Feldbæk Nielsen

The aim was to investigate trial-by-trial response characteristics in the short-latency stretch reflex (SSR). Fourteen dorsiflexion stretches were applied to the ankle joint with a precontracted soleus muscle on 2 days. The magnitude and variability of trial-by-trial responses of the SSR were assessed. The SSR was log-normally distributed and variance heterogeneous between subjects. For some subjects, the magnitude and variance differed between days and stretches. As velocity increased, variance heterogeneity tended to decrease and response magnitude increased. The current study demonstrates the need to assess trial-by-trial response characteristics and not averaged curves. Moreover, it provides an analysis of SSR characteristics accounting for log-normally distributed and variance heterogeneous trial-by-trial responses.

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Troy R. Garrett and Peter J. Neibert

Clinical Scenario:

Injury to the plantar fascia, whether acute or chronic, is common among many populations. A conventional multiple-treatment approach is commonly administered by health care providers, consisting of controlling inflammation, managing pain, and promoting healing. Frequently, the initial treatment for plantar fasciitis is targeted at increasing dorsiflexion range of motion by stretching the gastroc-soleus musculature. It has been theorized that inflexibility of the gastroc-soleus complex can lead to excessive pronation and overcompensation of the plantar fascia at the first metatarsal phalangeal joint, therefore increasing the stress at the medial calcaneal insertion. Therefore, it is deemed that gastrocnemius–soleus stretches are a beneficial treatment in the initial stage of a plantar fasciitis treatment or rehabilitation program.

Focused Clinical Question:

Is a gastrocnemius–soleus stretching program, as a stand-alone treatment variable, effective in the treatment of plantar fasciitis?

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Alan A. Zakaria, Robert B. Kiningham and Ananda Sen

Objective:

To determine if there is any benefit to static stretching after performing a dynamic warm-up in the prevention of injury in high school soccer athletes.

Design:

Prospective cluster randomized nonblinded study.

Setting:

12 high schools with varsity and junior varsity boys’ soccer teams (24 soccer teams) across the state of Michigan.

Participants:

Four hundred ninety-nine student-athletes were enrolled, and 465 completed the study. One high school dropped out of the study in the first week, leaving a total of 22 teams.

Interventions:

Dynamic stretching protocol vs dynamic + static (D+S) stretching protocol.

Main Outcome Measures:

Lower-extremity, core, or lower-back injuries per team.

Results:

Twelve teams performed the dynamic stretching protocol and 10 teams performed the D+S stretching protocol. There were 17 injuries (1.42 ± 1.49 injuries/team) among the teams that performed the dynamic stretching protocol and 20 injuries (2.0 ± 1.24 injuries/team) among the teams that performed the D+S protocol. There was no statistically significant difference in injuries between the 2 groups (P = .33).

Conclusions:

There is no difference between dynamic stretching and D+S stretching in the prevention of lower-extremity, core, and back injuries in high school male soccer athletes. Static stretching does not provide any added benefit to dynamic stretching in the prevention of injury in this population before exercise.

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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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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?