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Introduction: Static stretching (SS) program are widely used in clinical and athletic settings. Many previous studies investigate the effect of SS program on muscle strength and muscle architecture (muscle thickness, and pennation angleh). However, no consensus has been reached about the effect of SS programs on muscle strength and muscle architecture. The aim of this study was to investigate the effects of 6-week SS programs performed at different weekly frequencies on muscle strength, muscle thickness and pennation angle at different ankle joint positions., Methods: A total of 24 healthy male volunteers were performed 6-week SS programs (2,160 s of SS: 360 s/week*6 weeks) and were randomized to a group that performed SS once a week, or a group that performed SS three times per week. Total time under stretching was equated between groups. The muscle strength (maximum voluntary isometric contraction) at three different ankle joints were assessed before and after the 6-week SS program. In addition, muscle thickness and pennation angle were assessed by ultrasonography before and after 6-week SS program., Results: There were no significant changes in all variables before and after the 6-week SS program, regardless of weekly frequency (p > 0.05)., Conclusions: Our results suggest that 6-week SS programs do not increase muscle strength or muscle architecture at different ankle joint positions, regardless of stretching frequency; however, no negative effect on these outcomes was observed, contrary to evidence on the immediate, detrimental effects of SS., Competing Interests: The authors have read the journal’s policy and have the following competing interests: SN (Satoru Nishishita) is a paid employee of Tokuyukai Medical Corporation. This does not alter our adherence to PLOS ONE policies on sharing data and materials. There are no patents, products in development or marketed products associated with this research to declare.

In the course of investigating how common clinical treatments and adaptive technologies affect recovery after spinal cord injury (SCI), we discovered that a clinically-modeled hindlimb stretching protocol dramatically, but transiently, reduces locomotor function. Nociceptive sensory input is capable of altering motor output at the spinal level, and nociceptive neurons are sensitized after SCI. Here we tested the hypotheses that stretch-induced locomotor deficits are dependent on nociceptive afferents by depleting TRPV1+ sensory afferents using capsaicin injections in neonatal rats. Following maturation, animals received 25g-cm contusive SCI at T10. After plateau of locomotor recovery at 6 weeks, daily stretching was performed for 3 weeks, followed by 2 weeks without stretch, and again for two additional weeks. Animals were sacrificed 2 h after the last stretching session for histological assessments. Consistent with previous findings, stretch-induced drops in locomotor function were observed in nociceptor-intact animals but were nearly absent in nociceptor-depleted animals. These functional changes were accompanied by corresponding increases in the number of c-Fos+ nuclei throughout the lumbar enlargement. As expected, nociceptor-depleted animals had very little CGRP+ axonal innervation of the dorsal horn. Nociceptor-intact stretched animals had significantly higher levels of CGRP+ as compared to non-stretched SCI rats, suggesting that stretching promoted intraspinal CGRP+ sprouting. These results indicate that stretch-induced locomotor dysfunction in animals with incomplete SCI involves C-fibers, adding a negative post-SCI role to their adaptive roles (e.g., bladder control), and suggesting that the clinical use of muscle stretching to combat contractures and spasticity may be unintentionally detrimental to locomotor function., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Introduction: Chylothorax is a rare cause of pleural effusion. The most common causes are iatrogenic or medical. We report an unusual and rare cause of bilateral chylothorax., Case Report: A 73-year-old woman with no past history was admitted to the emergency department for sudden onset of dyspnoea. Chest X-ray and thoracic CT scan revealed large bilateral pleural effusions. Analysis of the fluid revealed a chylothorax. The patient was treated by chest tube drainage and a fat free (medium chain triglyceride) diet. This led to drying up of the effusions and rapid discharge. Complementary imaging examinations with chest-abdomen-pelvis CT, PET CT and pelvic MRI did not reveal any underlying cause. The final diagnosis was bilateral traumatic chylothorax caused by tearing of the thoracic duct during stretching exercises., Conclusion: Following a literature review, similar cases with the same clinical presentation were found. Combined treatment with thoracic drainage and medium chain triglyceride diet was effective in drying up the effusions. Our diagnosis was a diagnosis of exclusion. It is important to exclude a medical cause by thorough investigation., (Copyright © 2019 SPLF. Published by Elsevier Masson SAS. All rights reserved.)

Background: Reductions in one-repetition maximum lifts (1RM) following static stretching can be attributed to enhanced neural inhibition, which can be reduced by using stimulants like caffeine. This study compared knee-flexion 1RM following either static stretching (SS) or no-stretching (NS), as well as after ingesting either caffeine (C) or placebo (P)., Methods: Twenty-four participants (12 female, 12 male) performed four random counterbalanced knee flexion 1RM tests. A 1RM test was performed for each condition at the same time of day with ~48 hours separating each test. Static stretching consisted of 5 exercises with the 1RM being performed immediately following the stretching. Caffeine dose was 6 mg/kg body weight, and the placebo was methylcellulose (520 mg). Both doses were administered as pills 60 minutes before the SS or NS procedures., Results: Two-way repeated measures ANOVA showed a significant main effect for NS vs. SS (P<0.001, ηG2=0.23). The main effect for C vs. P, and the interaction between C vs. P and NS vs. SS were not statistically different. Average 1RMs were: CNS = 512±242 N, CSS = 474±241 N, PNS = 498±247 N, and PSS = 460±247 N., Conclusions: It is concluded that static stretching induced strength decrements are not removed by using stimulants at doses allowed by sport governing organizations.

There are many adult studies reporting static stretch (SS)-induced deficits and dynamic stretch (DS) performance improvements shortly after the intervention. However, there is only a single study examining stretch-induced performance changes with youth at 24 hours' post-stretch. The objective of this study was to examine physiological responses of young trained athletes at 24-hours after experiencing SS or DS protocols. Eight young male, elite handball players (age: 16.1±5.1 years) were tested prior to-, 3-minutes and 24-hours following the three conditions (DS, SS, Control) in a randomized and counterbalanced order. Similar volumes of SS (2 repetitions of 75s for each leg) and DS (5 repetitions of 30s for each leg) involved one stretch each for the quadriceps and hamstrings. Tests included (i) two 4s maximal voluntary isometric contractions (MVC) at 60° of knee flexion with 2-min rest, (ii) two maximal isokinetic contractions each at 60°/sec and 300°/sec with 1-min rest, and (iii) two drop jumps with 30-sec rest. To simulate a full warm-up, dynamic activity including 5 minutes of aerobic cycling (70 rpm; 1 kilopond), 4 submaximal isometric contractions and 4 drop jumps were instituted before the pre-tests and following the interventions. Two-way repeated measures ANOVAs revealed that 1) both the SS and control conditions exhibited knee extensor 60°.s-1 (SS:-10.3%; p = 0.04, Control: -8.7%; p = 0.07) and 300°.s-1 (SS: -12.9%; p = 0.005, Control: -16.3%; p = 0.02) isokinetic deficits at post-test, 2) DS impaired knee flexor 60°.s-1 isokinetic work and power-related measures at post-test (Work: -10.1%; p = 0.0006; Power: -19.1%; p = 0.08) and at 24-hours' post-test (Work: 9.9%; p = 0.023; Power: -9.6%; p = 0.01), 3) DS (12.07% and 10.47%) and SS (13.7% and 14.6%) enhanced knee flexor 300°.s-1 isokinetic force and power-related measures compared to control. In conclusion, testing-induced knee extensor isokinetic impairments were counterbalanced by DS, however the hip flexion DS could have produced minor muscle damage for at least 24-hours decreasing knee flexor forces and power at 60°.s-1., Competing Interests: The authors have declared that no competing interests exist.

Curcumin is known to have potent anti-inflammatory effects. We have reported that acute curcumin ingestion attenuates eccentric exercise-induced muscle damage. This study aimed to examine the effect of curcumin ingestion timing (before or after exercise) on the changes in muscle damage markers after eccentric exercise. In this randomized, single-blind, parallel design study, 24 healthy young men performed 30 maximal isokinetic (120º/s) eccentric contractions of the elbow flexors using an isokinetic dynamometer. Subjects were randomly assigned to ingest 180 mg/d of oral curcumin either 7 d before (PRE) or 4 d after exercise (POST) or 180 mg/d of oral placebo 4 d after exercise (CON). The maximal voluntary contraction (MVC) torque of the elbow flexors, elbow joint range of motion (ROM), muscle soreness, and serum creatine kinase (CK) activity were measured before, immediately after, and 1-4 d after exercise. Changes in these variables were compared over time. In the POST group, ROM were higher at 3-4 d and muscle soreness was lower at 3 d after exercise compared with the CON group (p<0.05). However, in the PRE group, there were no significant differences compared with the CON group in changes in ROM and muscle soreness. Meanwhile, there were no significant differences among the groups in terms of changes in MVC torque and serum CK activity. Our results suggest that curcumin ingestion after exercise had a more beneficial effect in attenuating muscle soreness.

Debilitating pain, stiffness, tenderness, fatigue, impaired muscle function, lack of strength subsequent to exercise are not welcomed by those not accustomed to it. It may discourage an individual from participating in regular exercise. Numerou s ph armacological and non - pharmacological strategies have been used to alleviate symptoms of muscle soreness, muscle pain, improving muscle function, the range of motion and recovery time. Non-steroidal anti-inflammatory drugs are suggested to have a beneficial impact on muscle soreness, but fail to rejuvenate muscle weakness and range of motion coupled with muscle soreness. Furthermore, oral antiinflammatory drugs are widely used to mitigate muscle soreness symptoms, but chronic use can lead to different side effects in terms of peptic ulcer and liver toxicity. Non-pharmacological remedies and interventions can be a better choice. This narrative review is intended to provide insight into the non-pharmacological strategies to combat exercise-induced muscle damage.

Background: Static and dynamic exercises are performed before activity to decrease injury risk and increase performance. Although evidence supports using dynamic over static stretching and performing Fédération Internationale de Football Association (FIFA) 11+ as a dynamic prepractice routine, we do not know the frequency at which these exercises are utilized in high school populations., Hypothesis: We hypothesize that there is a wide variety of preparticipation exercises performed by high school athletes, and that few high school teams perform FIFA 11+ as an injury prevention program in its entirety., Study Design: Observational study., Level of Evidence: Level 4., Methods: High school prepractice routines were observed for 185 teams (football, soccer, basketball, and lacrosse) over 1 season. The percentages of team warm-up routines that included components of FIFA 11+ were calculated, and the chi-square test was used to compare sex, sport, and level of competition., Results: Of a total 644 warm-up observations, 450 (69.9%) included only non-FIFA 11+ exercises, 56 (8.7%) included at least 1 FIFA 11+ exercise, and 38 (5.9%) included only jogging; 69 (10.6%) consisted only of sport-specific activities. The type of warm-up differed significantly between males and females ( P = 0.002), sports ( P < 0.001), and level of competition ( P < 0.001). Static stretching and athletes stretching on their own were observed in 14% and 15% of all observations. No team performed the FIFA 11+ injury prevention routine in its entirety., Conclusion: The type of warm-up differed by sex, sport, and level of competition. Static stretching was performed more frequently than anticipated, and an entire FIFA 11+ warm-up was never performed., Clinical Relevance: We need to identify the exercises that decrease injury and increase performance and better inform the athletic population about the risks and benefits of static and dynamic warm-up programs.

The purpose of this study was to determine the intra-rater, inter-examiner and inter-observer reliability of biceps femoris long head (BFlh) tendon strain using ultrasound imaging. Nineteen patients (age: 20.4 ± 0.35 y) were tested twice with a 1-wk interval. Each session included passive stretching from three different hip positions. Tests were performed independently by two examiners while BFlh tendon displacement (mm) and strain (%) were manually extracted from ultrasound video footages by two observers. Intra-rater comparisons revealed an intra-class correlation coefficient (ICC 2,1 ) range of 0.87 to 0.98 and a variability less than 4.74%. Inter-examiner comparisons revealed an ICC 2,1 range of 0.83 to 0.99 and less than 4.69% variability. Inter-observer ICCs ranged from 0.93 to 0.97 with variability less than 4.89%. Using a well-defined scanning protocol, two experienced examiners attained high levels of intra-rater agreement, with similarly excellent results for inter-rater and inter-observer reliability for BFlh tendon displacement and strain., (Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Joint contractures and spasticity are two common secondary complications of a severe spinal cord injury (SCI), which can significantly reduce quality of life, and stretching is one of the top strategies for rehabilitation of these complications. We have previously shown that a daily static stretching protocol administered to rats at either acute or chronic time points after a moderate or moderate-severe T10 SCI significantly disrupts their hindlimb locomotor function. The objective of the current study was to examine the effects of dynamic range of motion (ROM) stretching on the locomotor function of rats with SCI as an alternative to static stretching. Starting at 6 weeks post-injury (T10 moderate contusion) eight adult Sprague-Dawley rats were subjected to hindlimb stretching for 4 weeks. Our standard stretching protocol (six maneuvers to stretch the major hindlimb muscle groups) was modified from 1 min static stretch-and-hold at the end ROM of each stretch position to a dynamic 2 sec hold, 1 sec release rhythm repeated for a duration of 1 min. Four weeks of daily (5 days/week) dynamic stretching led to significant disruption of locomotor function as assessed by the Basso, Beattie, Bresnahan (BBB) Open Field Locomotor Scale and three-dimensional (3D) kinematic and gait analyses. In addition, we identified and analyzed an apparently novel hindlimb response to dynamic stretch that resembles human clonus. The results of the current study extend the observation of the stretching phenomenon to a new modality of stretching that is also commonly used in SCI rehabilitation. Although mechanisms and clinical relevance still need to be established, our findings continue to raise concerns that stretching as a therapy can potentially hinder aspects of locomotor recovery.

Purpose: Our previous study demonstrated that a single bout of stretching exercises acutely reduced arterial stiffness. We hypothesized that this acute vascular response is due to regional mechanical stimulation of the peripheral arteries. To test this hypothesis, we examined the effect of a single bout of passive one leg stretching on arterial stiffness, comparing the stretched and the non-stretched leg in the same subject., Methods: Twenty-five healthy young men (20.9 ± 0.3 years, 172.5 ± 1.4 cm, 64.1 ± 1.2 kg) volunteered for the study. Subjects underwent a passive calf stretching on one leg (six repetitions of 30-s static stretch with a 10-s recovery). Pulse wave velocity (PWV, an index of arterial stiffness), blood pressure (BP), and heart rate (HR) were measured before and immediately, 15, and 30 min after the stretching., Results: Femoral-ankle PWV (faPWV) in the stretched leg was significantly decreased from baseline (835.0 ± 15.9 cm/s) to immediately (802.9 ± 16.8 cm/s, P < 0.01) and 15 min (810.5 ± 16.0 cm/s, P < 0.01) after the stretching, despite no changes in systolic and diastolic BP, or HR. However, faPWV in the non-stretched leg was not significantly altered at any time. Brachial-ankle PWV (baPWV) also showed similar responses with faPWV, but this response was not significant. Additionally, the passive stretching did not alter carotid-femoral PWV (cfPWV)., Conclusions: These results suggest that mechanical stimulation to peripheral arteries as induced by static passive stretch may modulate arterial wall properties directly, rather than resulting in a systemic effect.

Purpose: This study evaluated the acute effects of two different stretch intensities on muscle damage and extensibility., Methods: Twenty-two physically active women (age 20 ± 1.0 years) were divided into two matched groups and undertook eight sets of 30-s passive hamstring stretching. One group stretched to the point of discomfort (POD) and the other to the point of pain (POP). Hamstring passive torque, sit and reach (S&R), straight leg raise (SLR), and markers of muscle damage were measured before, immediately after stretching and 24 h later., Results: S&R acutely increased and was still increased at 24 h with median (interquartile range) of 2.0 cm (0.5-3.75 cm) and 2.0 cm (0.25-3.0 cm) for POP and POD (p < 0.05), respectively, with no difference between groups; similar changes were seen with SLR. Passive stiffness fully recovered by 24 h and there was no torque deficit. A small, but significant increase in muscle tenderness occurred at 24 h in both groups and there was a very small increase in thigh circumference in both groups which persisted at 24 h in POP. Plasma CK activity was not raised at 24 h., Conclusion: Stretching to the point of pain had no acute advantages over stretching to the discomfort point. Both forms of stretching resulted in very mild muscle tenderness but with no evidence of muscle damage. The increased ROM was not associated with changes in passive stiffness of the muscle but most likely resulted from increased tolerance of the discomfort.

Purpose: It has been suggested that flexibility training may reduce the total volume of training during resistance trainings. The purpose of this study was to compare the effect of flexibility training immediately before resistance training (FLEX-RT) versus resistance training without flexibility training (RT) on maximum strength and the vastus lateralis muscle cross-sectional area (CSA)., Methods: Participants had each leg assigned to RT or FLEX-RT. Both groups performed four sets of leg extensions to voluntary failure of 80% of one repetition maximum (1RM); however, FLEX-RT performed two sets of 25 s of static stretching before resistance training. Number of repetitions and total volume were calculated during weeks 1-5 and 6-10. Vastus lateralis muscle CSA, 1RM, and flexibility were assessed at baseline and after 10 weeks., Results: The number of repetitions and total training volume were greater for RT than FLEX-RT for weeks 1-5 and 6-10. Regarding the vastus lateralis muscle CSA, a main time effect was observed, however, greater change was observed for RT than FLEX-RT (12.7 and 7.4%, respectively). A main time effect for 1RM was also observed with similar changes for RT and FLEX-RT (12.7 and 12.9%, respectively). Flexibility was increased pre- to post-training for FLEX-RT with greater change for FLEX-RT (10.1%) than RT (2.1%)., Conclusion: These results show that performing flexibility training immediately before resistance training can contribute to a lower number of repetitions, total volume, and muscle hypertrophy.

Background: NCAA strength and conditioning coaches are responsible for the day-to-day conditioning and strength training of collegiate athletes. NCAA regulations will likely require all strength and conditioning coaches to have a strength and conditioning certification. NCAA strength and conditioning coaches have varied philosophies on exercise programming based on educational background. The study aims to further evaluate the backgrounds and exercise philosophies of NCAA strength and conditioning coaches., Methods: A survey (Survey Monkey®, Palo Alto, CA, USA) was distributed to NCAA strength and conditioning professionals to evaluate their education background, current practice trends, use of specific equipment and footwear, and what injuries occurred during sessions., Results: Of the 208 survey participants, 77.9% were male with an average age of 34.5±9.1 years old. An exercise-related bachelor's degree was held by 80.4% and an exercise-related master's degree by 72.4%. Over 89% had a strength and conditioning certification. Having a master's, bachelor's, or type strength and conditioning certification had no difference in 1-repetition maximal practice with athletes. Lower extremity injuries made up the highest percentage (58.9%) of injuries seen by NCAA Strength and Conditioning Coaches than lumbar spine injuries (16.7%). The five most common injuries reported during workouts were lumbar strain (N.=431, 14.7%), hamstring strain (N.=332, 11.3%), ankle sprain (N.=299, 10.2%), patellar tendonitis (N.=232, 7.9%), and shin splints (N.=226, 7.7%)., Conclusions: Collegiate education and certifications have impact on practice patterns of strength and conditioning coaches in the NCAA.

Much of the static stretching (SS) literature reports performance impairments with prolonged SS. However, it has been acknowledged that a limitation of these studies is participants' knowledge or bias. Since many participants have knowledge of the literature, their performance may be subconsciously influenced by expectations. Hence, the objective of this study was to examine the effect of stretching knowledge or deception on subsequent force output following SS. Two groups of male participants who were either aware (BIASED: 14) or unaware (DECEPTION: 14) of the SS literature participated. Unaware participants were misinformed that SS increases force production. Testing involved maximal voluntary isometric contractions (MVC) of the quadriceps and hamstrings at pre-, post-, and 5 min post-intervention (three 30-s passive hamstring stretches to the point of discomfort with 30-s rest intervals) or control. While the DECEPTION group displayed impaired knee flexion force (p = 0.04; 3.6% and 10.4%) following hamstrings SS, there was no significant impairment with the BIASED (-1.1% and +0.9%) group. Both groups exhibited hamstrings F200 (force produced in the first 200 ms) impairments following SS. Whereas BIASED participants exhibited an overall decrease (p < 0.05; 1.8% and 4.2%) in knee extension MVC, DECEPTION participants showed (p = 0.005; 8.8% and 5.1%) force increases. The quadriceps F200 was not significantly affected with the BIASED group but overall there were 4.5% and 8.7% F200 impairments at 1 and 5 min post-intervention (p = 0.05) with the DECEPTION group. Thus while deception resulted in enhanced quadriceps muscle force output, there was no knowledge or deception advantage when stretching the hamstrings.

This study examined the effects of passive stretching only (PS+CON) and passive stretching with the addition of continuous vibration (VIB) during post-passive stretching tests (PS+VIB) on peak torque (PT), percent voluntary inactivation (%VI), single stimulus twitch torque (TTSINGLE), and doublet stimuli twitch torque (TTDOUBLET) of the plantar flexors at a short (20° plantar flexion (PF)) and long muscle length (15° dorsiflexion (DF)). Fourteen healthy men (age = 22 ± 3 years) performed isometric maximal voluntary contractions at PF and DF, and passive range of motion (PROM) assessments before and after 8 × 30-s passive stretches without (PS+CON) or with VIB (PS+VIB) administered continuously throughout post-passive stretching tests. The passive properties of the muscle tendon unit were assessed pre- and post-passive stretching via PROM, passive torque (PASSTQ), and musculotendinous stiffness (MTS) measurements. PT, TTSINGLE, and TTDOUBLET decreased, whereas, %VI increased following passive stretching at PF and DF (P < 0.05) with no significant differences between PS+CON and PS+VIB. PASSTQ and MTS decreased while PROM increased post-passive stretching during both trials (P < 0.05). The stretching-induced force/torque deficit and increases in %VI were evident following passive stretching at short and long muscle lengths. Although not statistically significant, effect size calculations suggested large and moderate differences in the absolute changes in PT (Cohen's d = 1.14) and %VI (Cohen's d = 0.54) from pre- to post-passive stretching between treatments, with PS+VIB having greater decreases of PT and higher %VI than PS+CON. The decrement in PT following passive stretching may be primarily neural in origin.

Gymnastics is noted for involving highly specialized strength, power, agility and flexibility. Flexibility is perhaps the single greatest discriminator of gymnastics from other sports. The extreme ranges of motion achieved by gymnasts require long periods of training, often occupying more than a decade. Gymnasts also start training at an early age (particularly female gymnasts), and the effect of gymnastics training on these young athletes is poorly understood. One of the concerns of many gymnastics professionals is the training of the spine in hyperextension-the ubiquitous 'arch' seen in many gymnastics positions and movements. Training in spine hyperextension usually begins in early childhood through performance of a skill known as a back-bend. Does practising a back-bend and other hyperextension exercises harm young gymnasts? Current information on spine stretching among gymnasts indicates that, within reason, spine stretching does not appear to be an unusual threat to gymnasts' health. However, the paucity of information demands that further study be undertaken.

Introduction: Stretching (St) has been used for treating denervated muscles. However, its effectiveness and safety claims require further study., Methods: Rats were divided into: (1) those with denervated (D) muscles, evaluated 7 or 15 days after sciatic nerve crush injury; (2) those with D muscles submitted to St during 7 or 15 days; and (3) those with normal muscles. Muscle fiber cross-sectional area, serial sarcomere number, sarcomere length, and connective tissue density were measured. MMP-2, MMP-9, TIMP-1, TGF-β1, and myostatin mRNAs were determined by real-time polymerase chain reaction. MMP-2 and MMP-9 activity was evaluated by zymography. Collagen I was localized using immunofluorescence., Results: St did not prevent muscle atrophy due to denervation, but it increased fibrosis and collagen I deposition at day 15. St also upregulated MMP-9 and TGF-β1 gene expressions at day 7, and myostatin at day 15., Conclusions: Stretching denervated muscle does not prevent atrophy, but it increases fibrosis via temporal modulation of TGF-β1/myostatin and MMP-9 cascades., (© 2015 Wiley Periodicals, Inc.)

Rupture of the peritoneal dialysis (PD) catheter is rare complication. Here, we report a case of catheter rupture that occurred because of exercise after partial catheter reimplantation.A 66-year-old man with a history of end-stage kidney disease secondary to diabetic nephropathy experienced refractory exit-site and tunnel infection. After the infected parts of the catheter were excised, a partial catheter reimplantation was performed. At the time of that surgery, a presternal location was selected for the new exit site, and a titanium extender was used to connect the two catheters. The patient was discharged on postoperative day 3, but was readmitted for a pericatheter leak 5 days later. Fluoroscopy performed to investigate the cause demonstrated a pericatheter leak from the connecting portion between the titanium extender and the catheter.Surgery performed to repair the leak revealed that the catheter had ruptured. We believe that the cause of the rupture was mechanical stress induced by the patient's stretching exercise program. The PD catheter was made of silicone rubber with high elasticity. Even when such resilient materials are used, we recommend that, to avoid PD catheter rupture after partial reimplantation, clinicians should discourage the patient from stretching excessively.

The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength was measured in 20 healthy people at four knee joint angles (90°, 70°, 50°, 30°) before and after stretching. One leg received SS, the contralateral received CRS. Both stretching techniques resulted in significant strength loss, which was most apparent at short muscle lengths [SS: P = 0.025; stretching × angle P < 0.001; 11.7% at 90° P < 0.01; 5.6% at 70° nonsignificant (ns); 1.3% at 50° ns; -3.7% at 30° ns. CRS: P < 0.001; stretching × angle P < 0.001; 17.7% at 90°, 13.4% at 70°, 11.4% at 50°, all P < 0.01, 4.3% at 30° ns]. The overall stretch-induced strength loss was greater (P = 0.015) after CRS (11.7%) vs SS (3.7%). The muscle length effect on strength loss was not different between CRS and SS (stretching × angle × stretching technique P = 0.43). Contrary to the hypothesis, CRS did not result in a greater shift in the length-tension relationship, and in fact, resulted in greater overall strength loss compared with SS. These results support the use of SS for stretching the hamstrings., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Recent investigations have suggested that static stretching (SS) performed before exercise reduces muscular performance. However, it is yet unknown whether dynamic warm-up exercises performed together with SS may actually minimize the detrimental acute effects of stretching on muscular performance. This study aimed to assess the effects of static shoulder stretching exercises, dynamic warm-up exercises, or both together, on muscular performance evaluated by ball throwing. Twenty-one female handball players (age: 16.2 ± 1.0 years [range: 14-18 years], height: 167.0 ± 10.0 cm [range: 158-179 cm], and body mass: 63.3 ± 7.6 kg [range: 50.4-77.4 kg]) performed SS, dynamic warm-up exercises or both, targeting the muscles of the upper limbs. Thereafter, medicine ball throwing distance and handball ball throwing speed tests were performed. Static stretching performed before the medicine ball throwing test reduced performance when compared with the warm-up exercises (95% confidence interval [CI] = 0.02-0.17, p ≤ 0.05, effect size [ES] = 0.34). When a warm-up exercise routine was added to SS, the detrimental effects of SS were abolished (95% CI = -0.01 to 0.18, p > 0.05, ES = 0.31). The throwing speed was the same over the 3 conditions. In conclusion, warm-up exercises performed together with SS abolished the impairment in medicine ball throwing distance. We recommend that athletes perform warm-up exercises together with SS before activity to avoid detrimental effects on muscle strength.

Purpose: Static stretching is used in sport practice but it has been associated with decrements in force and performance. Therefore, we examined the effect of short duration static stretch on the mechano-morphological properties of the m. vastus lateralis (VL) muscle tendon unit (MTU) and on the jumping performance., Methods: Eight males and three females (mean ± SD, 25.5 ± 3.1 years) stretched their lower legs for a 15 or 60 s duration or acted as their own control without stretching in a randomized order. In a pre-post design, a passive movement (5°/s) and a maximum voluntary knee extension contraction (MVC) were performed on dynamometer while the VL tendon and aponeurosis was observed via ultrasound. Furthermore, the participants performed countermovement (CMJ) and squat jumps (SJ)., Results: Repeated measures ANOVA did not show significant differences in MVC, active and passive strain, stiffness, elongation, knee joint angle range, and jump performance between and within groups., Conclusions: The applied stretch stimuli (15 or 60 s) were not sufficient to trigger adaptations in the mechano-morphological properties of the lower extremities MTU which therefore did neither affect jump performance nor MVC. As a possible mechanism, we hypothesized that the dose-time dependency effect of static stretch might have important implications when measuring functional parameters of the MTU and performance. Further examination is necessary to elucidate its impact in the examination of the MTU mechano-morphological properties.

The aim of the present study was to compare the acute effects of constant torque (CT) and constant angle (CA) stretching exercises on the maximum range of motion (ROMmax), passive stiffness (PS), and ROM corresponding to the first sensation of tightness in the posterior thigh (FSTROM). Twenty-three sedentary men (age, 19-33 years) went through 1 familiarization session and afterward proceeded randomly to both CA and CT treatment stretching conditions, on separate days. An isokinetic dynamometer was used to analyze hamstring muscles during passive knee extension. The subjects performed 4 stretches of 30 seconds each with a 15-second interval between them. In the CA stretching, the subject reached a certain ROM (95% of ROMmax), and the angle was kept constant. However, in the CT stretching exercise, the volunteer reached a certain resistance torque (corresponding to 95% of ROMmax) and it was kept constant. The results showed an increase in ROMmax for both CA and CT (p < 0.001), but the increase was greater for CT than for CA (CA vs. CT in poststretching, p = 0.002). Although the PS decreased for both CA and CT (p < 0.001), the decrease was greater for CT than for CA (CA vs. CT in poststretching, p = 0.002). The FSTROM increased for both CA and CT, but the increase for CT was greater than that for CA (CA vs. CT in poststretching, p = 0.003). The greater increase in ROMmax for the CT stretch may be explained by greater changes in the biomechanical properties of the muscle-tendon unit and stretch tolerance, as indicated by the results of PS and FSTROM.

Background: The safety of the manual treatment techniques such as spinal manipulation has been discussed and there is a need for more information about potential adverse events after manual therapy. The aim of this randomized controlled trial was to investigate differences in occurrence of adverse events between three different combinations of manual treatment techniques used by manual therapists (i.e. chiropractors, naprapaths, osteopaths, physicians and physiotherapists) for patients seeking care for back and/or neck pain. In addition women and men were compared regarding the occurrence of adverse events., Methods: Participants were recruited among patients, ages 18-65, seeking care at the educational clinic of the Scandinavian College of Naprapathic Manual Medicine in Stockholm. The patients (n = 767) were randomized to one of three treatment arms 1) manual therapy (i.e. spinal manipulation, spinal mobilization, stretching and massage) (n = 249), 2) manual therapy excluding spinal manipulation (n = 258) and 3) manual therapy excluding stretching (n = 260). Treatments were provided by students in the seventh semester of total eight. Adverse events were measured with a questionnaire after each return visit and categorized in to five levels; 1) short minor, 2) long minor, 3) short moderate, 4) long moderate and 5) serious adverse events, based on the duration and/or severity of the event. Generalized estimating equations were used to examine the association between adverse event and treatments arms., Results: The most common adverse events were soreness in muscles, increased pain and stiffness. No differences were found between the treatment arms concerning the occurrence of adverse event. Fifty-one percent of patients, who received at least three treatments, experienced at least one adverse event after one or more visits. Women more often had short moderate adverse events (OR = 2.19 (95% CI: 1.52-3.15)), and long moderate adverse events (OR = 2.49 (95% CI: 1.77-3.52)) compared to men., Conclusion: Adverse events after manual therapy are common and transient. Excluding spinal manipulation or stretching do not affect the occurrence of adverse events. The most common adverse event is soreness in the muscles. Women reports more adverse events than men., Trial Registration: This trial was registered in a public registry (Current Controlled Trials) (ISRCTN92249294).

It is previously demonstrated that static stretching was associated with a decrease in running economy and distance run during a 30-minute time trial in trained runners. Recently, the detrimental effects of static stretching on economy were found to be limited to the first few minutes of an endurance bout. However, economy remains to be studied for its direct effects on performance during shorter endurance events. The aim of this study was to investigate the effects of static stretching on 1-mile uphill run performance, electromyography (EMG), ground contact time (GCT), and flexibility. Ten trained male distance runners aged 24 ± 5 years with an average VO2max of 64.9 ± 6.5 mL·kg-1·min-1 were recruited. Subjects reported to the laboratory on 3 separate days interspersed by 72 hours. On day 1, anthropometrics and V[Combining Dot Above]O2max were determined on a motor-driven treadmill. On days 2 and 3, subjects performed a 5-minute treadmill warm-up and either performed a series of 6 lower-body stretches for three 30-second repetitions or sat still for 10 minutes. Time to complete a 1-mile run under stretching and nonstretching conditions took place in randomized order. For the performance run, subjects were instructed to run as fast as possible at a set incline of 5% until a distance of 1 mile was completed. Flexibility from the sit and reach test, EMG, GCT, and performance, determined by time to complete the 1-mile run, were recorded after each condition. Time to complete the run was significantly less (6:51 ± 0:28 minutes) in the nonstretching condition as compared with the stretching condition (7:04 ± 0:32 minutes). A significant condition-by-time interaction for muscle activation existed, with no change in the nonstretching condition (pre 91.3 ± 11.6 mV to post 92.2 ± 12.9 mV) but increased in the stretching condition (pre 91.0 ± 11.6 mV to post 105.3 ± 12.9 mV). A significant condition-by-time interaction for GCT was also present, with no changes in the nonstretching condition (pre 211.4 ± 20.8 ms to post 212.5 ± 21.7 ms) but increased in the stretching trial (pre 210.7 ± 19.6 ms to post 237.21 ± 22.4 ms). A significant condition-by-time interaction for flexibility was found, which was increased in the stretching condition (pre 33.1 ± 2 to post 38.8 ± 2) but unchanged in the nonstretching condition (pre 33.5 ± 2 to post 35.2 ± 2). Study findings indicate that static stretching decreases performance in short endurance bouts (∼8%) while increasing GCT and muscle activation. Coaches and athletes may be at risk for decreased performance after a static stretching bout. Therefore, static stretching should be avoided before a short endurance bout.

The aim of this study was to investigate the acute effects of static (SS) and dynamic stretching (DS) on explosive power, flexibility, and sprinting ability of adolescent boys and girls and to report possible gender interactions. Forty-seven active adolescent boys and girls were randomly tested after SS and DS of 40 seconds on quadriceps, hamstrings, hip extensors, and plantar flexors; no stretching was performed at the control condition. Pretreatment and posttreatment tests examined the effects of stretching on 20-m sprint run (20 m), countermovement jump (CMJ) height, and sit and reach flexibility test. In terms of performance, SS hindered 20 m and CMJ in boys and girls by 2.5 and 6.3%, respectively. Dynamic stretching had no effect on 20 m in boys and girls but impaired CMJ by 2.2%. In terms of flexibility, both SS and DS improved performance with SS being more beneficial (12.1%) compared with DS (6.5%). No gender interaction was found. It can therefore be concluded that SS significantly negates sprinting performance and explosive power in adolescent boys and girls, whereas DS deteriorates explosive power and has no effect on sprinting performance. This diversity of effects denotes that the mode of stretching used in adolescent boys and girls should be task specific.

The purpose of this study was to clarify the time course of the stretching-induced decrease in maximal isometric plantar flexion torque. Nineteen women participated in 2 randomly ordered experimental trials: static 5-minute stretching or control with no stretching. The participants performed isometric maximal voluntary contractions (MVCs) of the right plantar flexor muscles, whereas electromyographic (EMG) amplitude (root mean square) was calculated for the medial and lateral gastrocnemius muscles. Measurements were conducted preintervention; immediately after intervention; and 5, 10, 15, and 30 minutes postintervention. The static 5-minute stretching trial consisted of dorsiflexion to the end range of motion and holding that position for 1 minute, 5 times, whereas the control trial consisted of 5 minutes of resting. As a result, the MVC torque was significantly decreased immediately after, and 5 minutes after the static 5-minute stretching intervention compared with the preintervention value (p < 0.05), and this change recovered within 10 minutes. However, the EMG amplitude did not change from preintervention to postintervention under any conditions. These results suggest that the deficits of static stretching are disabled in a short time after static stretching.

This study examined whether passive static stretching reduces the maximum muscle strength achieved by different body segments in untrained and resistance-trained subjects. Twenty adult men were assigned to 1 of the following groups: untrained (UT, N = 9) and resistance-trained (RT, N = 11) groups. The subjects performed six 1 repetition maximum (1RM) load tests of the following exercises: horizontal bench press, lat pull-downs, bicep curls, and 45° leg press. The results achieved in the last two 1RM tests were used for statistical analyses. A passive static stretching program was incorporated before the sixth 1RM test. The body fat content was significantly higher in the UT group compared with the RT group (p < 0.0001). Moreover, the RT group showed significantly higher proportion of lean body mass compared with the UT group (p < 0.0001). Maximum muscle strength on all 4 exercises was significantly reduced in both groups after stretching (p < 0.01). Furthermore, the magnitude of muscle strength reduction was similar for the UT and the RT groups. The exception was for barbell curls, in which the muscle strength depression was significantly higher in the UT group compared with the RT group (p < 0.0001). In conclusion, the passive static stretching program was detrimental to upper- and lower-body maximal muscle strength performance in several body segments. The negative effects of stretching were similar for subjects participating in resistance training regimens.

Introduction: Warm-up exercises are commonly used before exercise as a method to physiologically prepare for strenuous physical activity. Various warm-up exercises are often implemented but without scientific merit and, at times, may be detrimental to performance., Purpose/objective: To date, no systematic reviews have examined the effectiveness of warm-up exercises for military physical fitness test (PFT) or combat fitness test (CFT). The purpose of this rapid evidence assessment of the literature was to examine the quantity, quality, and effectiveness of warm-up exercises for PFT and identify those that might increase PFT and/or CFT scores, as reported in the literature., Methods: Literature searches of randomized controlled trials were performed across various databases from database inception to May 2011. Methodological quality of included studies was assessed using the Scottish Intercollegiate Guidelines Network (SIGN) 50 criteria for randomized controlled trial designs, and studies were individually described. Subject matter experts summarized the results applicable or generalizable to military testing., Results: The search yielded a total of 1177 citations, with 37 fitting our inclusion criteria. Cardiovascular warm-ups increased sprint/running time, but dynamic stretching and dynamic warm-ups had the most positive outcome for the various exercise tests examined. Systematically, static stretching had no beneficial or detrimental effect on exercise performance but did improve range of movement exercises., Conclusions: Selected warm-up exercise may increase PFT and possibly CFT scores. Further research is needed to investigate the efficacy of dynamic stretching and dynamic warm-ups.

The purpose of this study was to determine if neural tension during passive stretching affected subsequent strength loss. Eleven healthy subjects (10 men, 1 woman; age 34 ± 12 years) performed maximal isometric hamstring contractions at 100°, 80°, 60°, and 40° knee flexion before and after five 1-minute hamstring stretches performed in either a spinal neutral position or a neural tension position. One leg was stretched in the neutral position and the other in the neural tension position. Hamstring electromyography (EMG) activity was recorded during all contractions and stretches. Passive resistance to stretch was reduced by 11% after stretching (p < 0.01; no difference between neutral or neural tension stretches p = 0.41). Stretch-induced strength loss was apparent after neural tension stretches (12%, p < 0.01) but not after neutral stretches (5%, p = 0.09). There was a rightward shift in the angle-torque curve after neutral stretches (strength loss on ascending limb, strength gain on descending limb, p < 0.01). This effect was not apparent after neural tension stretches (p = 0.43). Stretching did not affect EMG activity during isometric contractions (<2% decline p = 0.58; no difference between neutral and neural tension, p = 0.86). Hamstring stretching with the spine in a neutral position did not result in a significant strength loss but shifted the length-tension relationship such that strength was decreased at short muscle lengths and increased at long muscle lengths. Hamstring stretching with increased neural tension resulted in strength loss with no associated shift in the length-tension relationship.

We applied a meta-analytical approach to derive a robust estimate of the acute effects of pre-exercise static stretching (SS) on strength, power, and explosive muscular performance. A computerized search of articles published between 1966 and December 2010 was performed using PubMed, SCOPUS, and Web of Science databases. A total of 104 studies yielding 61 data points for strength, 12 data points for power, and 57 data points for explosive performance met our inclusion criteria. The pooled estimate of the acute effects of SS on strength, power, and explosive performance, expressed in standardized units as well as in percentages, were -0.10 [95% confidence interval (CI): -0.15 to -0.04], -0.04 (95% CI: -0.16 to 0.08), and -0.03 (95% CI: -0.07 to 0.01), or -5.4% (95% CI: -6.6% to -4.2%), -1.9% (95% CI: -4.0% to 0.2%), and -2.0% (95% CI: -2.8% to -1.3%). These effects were not related to subject's age, gender, or fitness level; however, they were more pronounced in isometric vs dynamic tests, and were related to the total duration of stretch, with the smallest negative acute effects being observed with stretch duration of ≤ 45 s. We conclude that the usage of SS as the sole activity during warm-up routine should generally be avoided., (© 2012 John Wiley & Sons A/S.)

Recent evidence has shown acute static stretching may decrease hamstring-to-quadriceps (H:Q) ratios. However, the effects of static stretching on the functional H:Q ratio, which uses eccentric hamstrings muscle actions, have not been investigated. This study examined the acute effects of hamstrings and quadriceps static stretching on leg extensor and flexor concentric peak torque (PT), leg flexor eccentric PT, and the conventional and functional H:Q ratios. Twenty-two women (mean ± SD age=20.6 ± 1.9 years; body mass=64.6 ± 9.1 kg; height=164.5 ± 6.4 cm) performed three maximal voluntary unilateral isokinetic leg extension, flexion, and eccentric hamstring muscle actions at the angular velocities of 60 and 180°/s before and after a bout of hamstrings, quadriceps, and combined hamstrings and quadriceps static stretching, and a control condition. Two-way repeated measures ANOVAs (time × condition) were used to analyze the leg extension, flexion, and eccentric PT as well as the conventional and functional H:Q ratios. Results indicated that when collapsed across velocity, hamstrings-only stretching decreased the conventional ratios (P<0.05). Quadriceps-only and hamstrings and quadriceps stretching decreased the functional ratios (P<0.05). These findings suggested that stretching may adversely affect the conventional and functional H:Q ratios., (© 2011 John Wiley & Sons A/S.)

Introduction: The benefits of preexercise muscle stretching have been recently questioned after reports of significant poststretch reductions in force and power production. However, methodological issues and equivocal findings have prevented a clear consensus being reached. As no detailed systematic review exists, the literature describing responses to acute static muscle stretch was comprehensively examined., Methods: MEDLINE, ScienceDirect, SPORTDiscus, and Zetoc were searched with recursive reference checking. Selection criteria included randomized or quasi-randomized controlled trials and intervention-based trials published in peer-reviewed scientific journals examining the effect of an acute static stretch intervention on maximal muscular performance., Results: Searches revealed 4559 possible articles; 106 met the inclusion criteria. Study design was often poor because 30% of studies failed to provide appropriate reliability statistics. Clear evidence exists indicating that short-duration acute static stretch (<30 s) has no detrimental effect (pooled estimate = -1.1%), with overwhelming evidence that stretch durations of 30-45 s also imparted no significant effect (pooled estimate = -1.9%). A sigmoidal dose-response effect was evident between stretch duration and both the likelihood and magnitude of significant decrements, with a significant reduction likely to occur with stretches ≥ 60 s. This strong evidence for a dose-response effect was independent of performance task, contraction mode, or muscle group. Studies have only examined changes in eccentric strength when the stretch durations were >60 s, with limited evidence for an effect on eccentric strength., Conclusions: The detrimental effects of static stretch are mainly limited to longer durations (≥ 60 s), which may not be typically used during preexercise routines in clinical, healthy, or athletic populations. Shorter durations of stretch (<60 s) can be performed in a preexercise routine without compromising maximal muscle performance.

A 47-year-old female patient who experienced urinary urgency after having stretching exercises of her legs is presented. Stretching of the legs are thought to be responsible for conus medullaris tethering which in turn causes urinary complaints. What is interesting in this case is that her complaints about urinary urgency stopped as she quit stretching exercise movements of her legs. There are some examples of such cases in the literature. The urinary urgency after stretching exercises warned us to investigate this patient in regard to tethered conus medullaris. Tethering of the conus medullaris can be temporary and can cause reversible functional disorders of the bladder. Incontinence at any age should be evaluated cautiously as it could be a sign of an underlying important developmental failure.

Middle-aged individuals may not respond in a similar manner as younger individuals. The study's objective was to examine the effect of static (SS) and dynamic stretching (DS) in young and middle-aged men on subsequent performance. Ten young (22 ± 1.4 years) and 8 middle-aged men (46.3 ± 6.5 years) participated in 3 conditions consisting of SS (4 × 30 s for right and left quadriceps, hamstrings, and plantar flexors), DS (8 × 30 s of bilateral butt kicks, walking lunges, and plantar flexors) and control. Dependent variables included sit and reach, hip extension flexibility, countermovement jump (CMJ) height, drop jump (DJ) height, static balance, reaction (RT) and movement time (MT). Measurements were taken pre-intervention, post- and 10 min post-intervention. A 3-way repeated measurement ANOVA revealed that the younger men had higher jump heights, faster RT and MT, and greater flexibility than the middle-aged men. DS significantly enhanced DJ (p = 0.04) and CMJ (p = 0.006) height compared with SS and control conditions. SS (p < 0.0001) and DS (p = 0.004) post-intervention sit and reach scores were significantly greater than pre-intervention scores. There were no significant differences between the SS and DS sit and reach scores. CMJ heights were impaired (p = 0.04) by SS. Conversely, DS post-intervention jump heights were significantly (p < 0.0001) higher than SS post-, control post-, and control 10 min post-intervention. SS-induced impairments and DS-induced enhancements of CMJ height were not affected by age. DS provided similar improvements in sit and reach scores as SS. DS is recommended as the most appropriate stretching routine prior to work or athletic performance for younger and middle-aged men.

An objective of a warm-up prior to an athletic event is to optimize performance. Warm-ups are typically composed of a submaximal aerobic activity, stretching and a sport-specific activity. The stretching portion traditionally incorporated static stretching. However, there are a myriad of studies demonstrating static stretch-induced performance impairments. More recently, there are a substantial number of articles with no detrimental effects associated with prior static stretching. The lack of impairment may be related to a number of factors. These include static stretching that is of short duration (<90 s total) with a stretch intensity less than the point of discomfort. Other factors include the type of performance test measured and implemented on an elite athletic or trained middle aged population. Static stretching may actually provide benefits in some cases such as slower velocity eccentric contractions, and contractions of a more prolonged duration or stretch-shortening cycle. Dynamic stretching has been shown to either have no effect or may augment subsequent performance, especially if the duration of the dynamic stretching is prolonged. Static stretching used in a separate training session can provide health related range of motion benefits. Generally, a warm-up to minimize impairments and enhance performance should be composed of a submaximal intensity aerobic activity followed by large amplitude dynamic stretching and then completed with sport-specific dynamic activities. Sports that necessitate a high degree of static flexibility should use short duration static stretches with lower intensity stretches in a trained population to minimize the possibilities of impairments.

A mandibular body fracture related to mouth-opening training in a dialysis patient is reported. A 61-year-old male patient had noticed pain in the right mandibular body and difficulty in mouth opening a week previously. The patient had been performing mouth-opening training for a couple of weeks. The right lower face was slightly swollen with tenderness at the right lower border of the mandible. Hypoesthesia of the right lower lip was also observed. A bone step was palpable on the alveolar ridge of the right mandible, but mobility was not marked. The mandible was atrophic in the body region with only four anterior teeth left. Panoramic X-ray examination revealed a moderately displaced fracture in the right molar region of the mandible. The patient had no severe pain or difficulty in eating using a partial denture. The patient had received dialysis for 17 years and had also been treated by warfarin and aspirin. The patient was followed up under restricted mouth opening. Osteosynthesis with bone remodeling was confirmed after 6 months by X-ray examination. No complication requiring further treatment occurred during the follow-up period. In this patient, a medically compromised condition under long-term dialysis is considered a predisposing factor, which made the atrophic mandible more susceptible to the stress related to mouth-opening training., (© 2011 John Wiley & Sons A/S.)

The triangularis sterni (TS) is an expiratory muscle that is passively stretched during inspiration. The magnitude of passive stretch depends upon the location of individual fibers within the TS muscle, with fibers located more caudally being stretched ∼ 5% to 10% more than fibers in the cephalad region. In the mdx mouse model for muscular dystrophy, the TS exhibits severe pathological alterations that are ameliorated by treatment with inhibitors of the NF-κB pathway. The purpose of this study was to assess the influence of passive stretch in vivo on fiber morphology in nondystrophic and mdx TS muscles, and the morphological benefits of treating mdx mice with two distinct NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC), and ursodeoxycholic acid (UDCA). Transmission electron microscopy revealed Z-line streaming, hypercontraction, and disassociation of the plasma membrane from the basal lamina in mdx fibers. In both nondystrophic and mdx TS muscles, fiber density was larger in more caudal regions. In comparison with nondystrophic TS, fibers in the mdx TS exhibited substantial reductions in diameter throughout all regions. In vivo treatment with either PDTC or UDCA tended to increase fiber diameter in the middle and decrease fiber diameter in the caudal TS, while reducing centronucleation in the middle region. These results suggest that passive stretch induces hypercontraction and plasma membrane abnormalities in dystrophic muscle, and that differences in the magnitude of passive stretch may influence fiber morphology and the actions of NF-κB inhibitors on dystrophic morphology., (2010 Wiley-Liss, Inc.)

Background: Hamstring stretching is an integral component in the treatment for knee flexion contracture in cerebral palsy (CP). As hamstrings span across hip and knee joints, passive stretching of hamstrings applies force to the hip that is often dysplasia in CP. The purpose of this study is to measure the dynamic displacement of femoral head produced by passive stretching of hamstrings and to determine the factors associated with the phenomenon., Methods: Children with spastic CP were studied using computerized tomography (CT) of the pelvis. Two sets of CT studies were carried out, one with the knee flexed and the hip flexed (resting) and the other with the knee extended and the hip flexed to simulate manual hamstrings stretching. The distance from pelvic baseline to the posterior margin of femoral epiphysis was measured on the CT images and compared between resting and stretching for dynamic displacement. The dynamic displacement of the femoral head was expressed by a ratio to femoral epiphysis diameter., Results: Twenty-seven CP children had CT studies at a mean age of 6.8 years (range: 4.5 to 9.6 y). Ten children were ambulators with or without devices and the other 17 children were nonambulators. On plain radiographs of the pelvis, the mean Reimer's migration percentage was 39% (range: 13% to 92%). On CT scan, dynamic displacement by stretching was 4.7% (range: -3.8% to 16.1%) of femoral epiphysis diameter (P<0.001 by paired t test). The displacement in the 33 hips with migration percentage of greater than 30% was significantly greater than the displacement in the other 21 hips with migration percentage of less than 30% (7.4% vs. 0.5%, P=0.001)., Conclusions: Passive stretching of spastic hamstrings in the hip flexion position resulted in dynamic posterior displacement of the femoral head. Medical professionals should be aware of this fact, especially in spastic CP children with a higher migration percentage on radiograph., Level of Evidence: Diagnostic II.

Purpose: Preeclampsia is a leading cause of perinatal mortality and morbidity, and it increases maternal risk for future cardiovascular disease. The purpose of the study was to explore the relationships among stretching exercise, autonomic cardiac response, and the development of preeclampsia., Design: Secondary data analysis., Methods: Heart rate and pulse pressure were longitudinally examined in this secondary data analysis among women who engaged in stretching exercise daily from 18 weeks of gestation to the end of pregnancy compared with women who did walking exercise daily during the same time period. A total of 124 women were randomized to either stretching (n=60) or walking (n=64) in the parent study., Findings: Heart rates in the stretching group were consistently lower than those in the walking group., Conclusions: Based on the results of this secondary data analyses, a physiologic framework for possible beneficial effects of stretching exercise by enhancing autonomic responses on reducing risks for preeclampsia is proposed and discussed., Clinical Relevance: If the protective effect is established, stretching exercise can be translated into nursing intervention for prenatal care.

Skeletal muscle cells are hypertrophied by mechanical stresses, but the underlying molecular mechanisms are not fully understood. Two signaling pathways, phosphatidylinositol 3-kinase (PI3K)/Akt to target of rapamycin (TOR) and extracellular signal-regulated kinase kinase (MEK) to extracellular signal-regulated kinase (ERK), have been proposed to be involved in muscle hypertrophy. In this study we examined the involvement of these pathways in primary cultures of chick skeletal myotubes subjected to passive cyclic stretching for 72 hours, a time that was sufficient to induce significant hypertrophy in our preparations. Hypertrophy was largely suppressed by wortmannin or rapamycin, inhibitors of PI3K or mTOR, respectively. Furthermore, phosphorylation of Akt was enhanced by stretching and suppressed by wortmannin. The MEK inhibitor, U0126, exerted a minimal influence on stretch-induced hypertrophy. We found that cyclic stretching of myotubes activates the PI3K/Akt/TOR pathway, resulting in muscle hypertrophy. The MEK/ERK pathway may contribute negatively to spontaneous hypertrophy.

There is substantial evidence that static stretching may inhibit performance in strength and power activities. However, most of this research has involved stretching routines dissimilar to those practiced by athletes. The purpose of this study was to evaluate whether the decline in performance normally associated with static stretching pervades when the static stretching is conducted prior to a sport specific warm-up. Thirteen netball players completed two experimental warm-up conditions. Day 1 warm-up involved a submaximal run followed by 15 min of static stretching and a netball specific skill warm-up. Day 2 followed the same design; however, the static stretching was replaced with a 15 min dynamic warm-up routine to allow for a direct comparison between the static stretching and dynamic warm-up effects. Participants performed a countermovement vertical jump and 20m sprint after the first warm-up intervention (static or dynamic) and also after the netball specific skill warm-up. The static stretching condition resulted in significantly worse performance than the dynamic warm-up in vertical jump height (-4.2%, 0.40 ES) and 20m sprint time (1.4%, 0.34 ES) (p<0.05). However, no significant differences in either performance variable were evident when the skill-based warm-up was preceded by static stretching or a dynamic warm-up routine. This suggests that the practice of a subsequent high-intensity skill based warm-up restored the differences between the two warm-up interventions. Hence, if static stretching is to be included in the warm-up period, it is recommended that a period of high-intensity sport-specific skills based activity is included prior to the on-court/field performance.

Spinal epidural hematoma (SEH) is a rare but serious condition. Common causes of SEH include spinal fracture, spinal trauma, and invasive spinal procedures such as lumbar puncture, epidural anesthesia, or myelography. A few previous reports have suggested that SEH could be caused by minor triggers such as spinal manipulation therapy or spontaneously in rare cases. A 60-year-old man, immediately after stretch exercise, developed severe back cervicodynia and rapidly progressive weakness of left arm from SEH. He was treated by decompression laminectomy and evacuation of the hematoma. However, the upper extremity weakness did not completely resolve. The standard treatment remains timely surgical decompression and evacuation of the hematoma. Thus, early diagnosis and treatment can confer a significant prognostic advantage to patients with SEH. Based on the finding that SEH was caused by a mild mechanical trigger and neurologic deficits remained in this patient, this report highlights its diagnostic difficulty as well as the importance of rapid treatment. Emergency physicians should consider SEH among the differential diagnosis in patients with sudden-onset back pain with symptoms and signs of spinal cord compression.