Speed effect of selected Tai Chi Chuan movement on leg muscle activity in young and old practitioners

Background

Tai Chi Chuan is becoming a popular exercise for improving balance and preventing falls in the elderly. To date, there is no quantitative study investigating the effect of Tai Chi Chuan movement speed on leg muscle function. This study investigated the effect of Tai Chi Chuan exercise performed at different speed on leg muscle activity characteristics in both young and old Tai Chi Chuan practitioners.

Methods

Surface electromyography of six leg muscles and kinematics of lower extremity joints were measured in young and old subjects during Tai Chi Chuan practice at fast, normal, and slow speed, respectively. The magnitude and duration of activation, and durations of isometric, concentric and eccentric actions of each muscle were compared among three speeds and between two groups.

Findings

The activation duration of all six leg muscles was significantly longer at slower speed than at faster speed (P < 0.039). The durations of isometric, concentric and eccentric actions were either longer at the slower speed or did not change with speed for all six leg muscles. The action of knee extensor was primarily isometric at slower speed (P = 0.004), and increased significantly to concentric and eccentric at faster speed (P < 0.031). The activation magnitude of posterior leg muscles increased with speed (P < 0.009). The old subjects had significantly shorter activation duration and lower activation magnitude in several leg muscles than the young, but similar speed effect as the young.

Interpretation

The activation duration and function of leg muscles, especially the knee extensor muscle, are significantly affected by the speed of the selected Tai Chi Chuan movement. Practicing Tai Chi Chuan at different speed may alter the role of muscular function in movement control.     

Comparative analysis of core muscle activation according to the use of props and the different knee angle during the modified Pilates Hundred

BackgroundThere are not so many Pilates studies related to muscle activation. Since the effectiveness and efficiency of the Pilates Hundred to muscle activation has recently emerged, it is necessary to investigate the effects of the Pilates Hundred on core muscles.ObjectivesThe purpose of this study was to determine what difference occurs in the muscle activity, during the Pilates Hundred, to suggest the optimal props for muscle function improvement and then to provide data for the efficient exercise program.MethodsTwenty-eight men in their twenties who were able to fully conduct Pilates Hundred. According to the difference between the small tool application (no prop: NP, soft ball mini: SB, Pilates ring: PR) and the knee joint angle (90° and 180°), muscle activations of rectus abdominis (RA), external oblique (EO), rectus femoris (RF), lateral muscle (vastus lateralis: VL), medial muscle (vastus medialis: VM), biceps femoris (BF), and semitendinosus (ST) were measured by the using surface electromyography (EMG) while different exercise conditions.ResultsDuring Pilates Hundred, the use of tools was found to be more effective in activating the core muscle (NP < SB < PR). During Pilates Hundred, 180° of knee angle had more influence on core muscle activation than 90°, and knee angle and props use showed an interaction for activating core muscles.ConclusionThe Pilates Hundred with PR and 180° knee angle intervention can increase core muscle activation, and this leads to effective Pilates exercise program for those who need to enhance core muscle volume and function and to rehabilitate core muscles.     

The effects of pilates training on flexibility and body composition: An observational study

OBJECTIVE: To assess claims regarding the effects of Pilates training on flexibility, body composition, and health status. DESIGN: An observational prospective study. SETTING: A community athletic club. PARTICIPANTS: A sample of 47 adults (45 women, 2 men) who presented for Pilates training. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Fingertip-to-floor distance, truncal lean body mass by bioelectric impedance, health status by questionnaire and visual analog scale were assessed at baseline, 2, 4, and 6 months (+/-1 wk). RESULTS: Thirty-two of 47 enrolled subjects met the protocol requirements of missing no more than 1 weekly 1-hour session Pilates mat class during each 2-month period. Investigators were blinded to measurements from previous time points. Median (interquartile range [IQR]) fingertip-to-floor distance improved from baseline by 3.4 cm (1.3-5.7 cm), 3.3 cm (0.3- 7.8 cm), and 4.3 cm (1.5-7.6 cm) at 2, 4, and 6 months, respectively (paired nonparametric analysis, all P<.01). There were no statistically significant changes in truncal lean body mass, height, weight, or other body composition parameters. Self-assessment of health also did not change in a statistically significant manner from its baseline median (IQR) value of 77 mm (69-85 mm). CONCLUSIONS: Pilates training may result in improved flexibility. However, its effects on body composition, health status, and posture are more limited and may be difficult to establish. Further study might involve larger sample sizes, comparison with an appropriate control group, and assessment of motor unit recruitment as well as strength of truncal stabilizers.     

Resistance training improves muscle function and body composition in patients with hyperthyroidism

OBJECTIVE: To evaluate the effect of resistance training on skeletal muscle performance and body composition in patients with medically treated hyperthyroidism. DESIGN: Nonrandomized controlled trial. SETTING: Large public tertiary hospital. PARTICIPANTS: Sixteen sedentary patients with recent clinical diagnosis and laboratory confirmation of hyperthyroidism (7 men, 9 women; age, 38+/-11 y; weight, 58.4+/-2.6 kg; height, 1.6+/-0.3m) were assigned to the control group (medical therapy; n=9) or training group (medical therapy associated with resistance training; n=7). An age- and sex-matched healthy group served as controls (3 men, 5 women; age, 40+/-3 y; weight, 68.4+/-4.3 kg; height, 1.6+/-0.3m). INTERVENTION: Resistance training twice a week for 16 weeks. MAIN OUTCOME MEASURES: Peak muscular strength (by dynamometry and 1 repetition maximum method) and endurance (30% of peak force) for 7 movements and anthropometric measurements. RESULTS: The hyperthyroid patients as a group had lower baseline overall strength values when compared with healthy subjects (200.3+/-16.0 kg vs 274.9+/-21.8 kg, respectively; P=.006). Overall absolute increases in strength (49 kg vs 91 kg, P<.05) and endurance (78.5x10(2)kg/s vs 176.9x10(2)kg/s, P<.05) were higher in the training group compared with the control group. Body weight increased in both groups, but the sum of muscular circumference increased only in the training group (training group, 92.6+/-3.3 cm vs 97.1+/-3.8 cm; control group, 94.6+/-2.2 cm vs 94.4+/-2.1cm; P<.05), with no change in the sum of skinfolds. CONCLUSIONS: Resistance training accelerates the recovery of skeletal muscle function and promotes weight gain based on muscle mass improvement in patients with medically treated hyperthyroidism.     

耐力运动对大鼠骨骼肌细胞葡萄糖运载体的影响

目的研究耐力运动对大鼠骨骼肌细胞葡萄糖运载体４（ＧＴ４）的影响。方法将ＳＤ大鼠随机分为二组：对照组和耐力运动组。耐力运动组大鼠进行６周游泳训练。制备ＧＴ４羧基端１２肽的多克隆抗体。以Ｗｅｓｔｅｒｎ印迹法对二组大鼠骨骼肌细胞ＧＴ４含量进行检测,同时检测大鼠血清胰岛素和血糖浓度。结果大鼠经过６周耐力运动,与对照组大鼠相比,骨骼肌细胞ＧＴ４含量增加３５．０％（Ｐ＜０．０１）。结论耐力运动可增加骨骼肌细胞内ＧＴ４含量,从而提高肌细胞对葡萄糖的摄取和利用     

Effects of whole-body vibration on muscle strength,quadriceps muscle thickness and functional capacity in kidney transplant recipients: A randomized controlled trial

BackgroundWhole-body vibration (WBV) may be an alternative of physical training for kidney transplant recipients.ObjectiveTo evaluate the effect of a training program on quadriceps muscle strength and thickness, distance walked in the 6-min walking test (6MWT), respiratory muscle strength and quality of life in adult kidney transplant recipients.DesignRandomized controlled clinical trial.MethodTwelve kidney transplant recipients of both genders who underwent WBV training (35 Hz) twice a week for 12 weeks on alternate days (WBVG), and training with a Sham Group (SG) were evaluated before and after intervention.ResultsNo difference was observed in quadriceps muscle strength and thickness between groups, however a large (d = 0.81) and a small (d = 0.44) effect size were observed after the training, respectively. Both groups improved the execution time of Sit-to-Stand Test before and after analysis, but this effect did not show superiority between them, however there was a large effect size provided by training (d = 1.11). No changes were observed between groups in relation to inspiratory muscle strength, but training effects could be observed by the effect size after the study period (d = 0.59). No changes were observed regarding the distance walked in the 6MWT and the effect size was small (d = 0.31).ConclusionWBV program would induce physiological responses that must be taken into consideration in adults’ kidney transplant recipients. Our results show considerable effect sizes were observed for muscle strength and quadriceps thickness, inspiratory muscle strength, and 6MWT walking distance, although no difference was observed between groups at the end of the study.     

Immediate effects of active cranio-cervical flexion exercise versus passive mobilisation of the upper cervical spine on pain and performance on the cranio-cervical flexion test

This study compared the immediate effects of an assisted plus active cranio-cervical flexion exercise (exercise group) versus a passive mobilisation plus assisted cranio-cervical flexion (mobilisation group) on performance of the cranio-cervical flexion test (CCFT), cervical range of motion (ROM) and pain in patients with chronic neck pain. Eighteen volunteers with chronic idiopathic neck pain participated in the study and were randomised to one of the two intervention groups. Current level of pain, cervical ROM and pain perceived during movement, pressure pain threshold (PPT) and surface electromyography (EMG) during performance of the CCFT were measured before and immediately after the intervention. A significant reduction in resting pain and PPT measured over cervical sites was observed immediately following both interventions, although a greater change was observed for the exercise group. No change in cervical ROM was observed after either intervention. Reduced sternocleidomastoid and anterior scalene EMG amplitude were observed during stages of the CCFT but only for the participants in the active exercise group. Although both active and passive interventions offered pain relief, only the exercise group improved on a task of motor function highlighting the importance of specific active treatment for improved motor control of the cervical spine.     

肌电生物反馈在半月板切除术后股四头肌功能恢复中的应用

将２５名半月板切除术后的患者，随机分成肌电生物反馈治疗线及对照组，指导患者进行股四头肌等长训练，训练前后均进行股四头肌的肌电水平、患肢负重及股四头肌徒手肌力测定。结果表明：训练后股四头肌的肌电增加增度肌电生物反馈组明显大于对照组（Ｐ＜０．０１）；在患肢负重能力方面，两组对比，反馈治疗组明显成于对照组（Ｐ＜０．０１）；训练前后的肌力测定显示；反馈治疗组训练后股四头肌肌力达到Ｖ组的百分率是６４．２％，     

Effects of different verbal instructions on change of lumbar multifidus muscle thickness in asymptomatic adults and in patients with low back pain

Background: Spinal stabilisation exercise has been shown to be effective in the rehabilitation of low back pain (LBP). Due to the isometric nature of spinal stabilisation exercise, manual therapists use various verbal instructions to elicit lumbar multifidus muscle contraction.

Objectives: The purpose of this study was to assess whether or not three verbal instructions would alter muscle thickness of the lumbar multifidus muscle differently in asymptomatic individuals and patients with LBP.

Methods: Three verbal instructions were selected for this study: (1) swell the muscle underneath the transducer, (2) draw your belly button in towards your spinal column and (3) think about tilting your pelvis but without really doing it. Lumbar multifidus muscle thickness was determined using parasagittal ultrasound (US) imaging. Measurements of muscle thickness were collected at rest and during verbal instructions from 21 asymptomatic adults and 21 patients with LBP. Percent changes of muscle thickness during contraction and at rest were compared between groups and across verbal instructions.

Results: ANOVA results showed no significant interaction for both L4-5 and L5-S1, but a significant main effect of verbal instruction (P?=?0.049) at L4-5.Post hoc analysis showed a greater increase with verbal instruction #3 than verbal instruction #2 (P?=?0.009). There was no significant main effect of group at either segment.

Discussion: The results of the study suggest that both groups responded similarly to the three verbal instructions. Verbal instructions may increase lumbar multifidus muscle thickness by different amounts at L4-5, but by the same amount at L5-S1.     

Effects of cervical manipulation on pain,grip force control,and upper extremity muscle activity: a randomized controlled trial

Objectives: Individuals with neck pain experience disrupted grip force control when performing manipulative tasks. Manipulative physical therapy might decrease pain and change the activity of surrounding muscles; however, its effect on upper limb motor control remains undetermined. This study aims to analyze the effects of cervical manipulation on pressure pain threshold (PPT), upper extremity muscle activity along with grip force control in individuals with neck pain.

Methods: Thirty subjects with neck pain were instructed to grasp and lift an object before and after cervical (n = 15) or sham (n = 15) manipulation. The patients’ PPT, electromyographic (EMG) activity of the upper extremity/scapular muscles, and grip force control were analyzed before and after one session of manipulation.

Results: No significant differences were found in the grip force control, PPT and EMG activity variables between groups.

Discussion: These results suggest that a single session of cervical manipulation may not modify upper limb motor control, more specifically grip force control and EMG activity, in patients with cervical pain. Future studies should investigate potential changes in grip force control in patients with different features of neck pain and/or by applying long-term treatment.

Level of Evidence: 1b.     

Effects of 6-weeks of detraining on functional capacity and rapid torque production in older women

Mat Pilates has become an attractive alternative exercise among older women, however, despite knowing the importance of regular exercise, interrupting training is a common issue in this population. The aim of the current study was to evaluate the effects of 6-weeks of detraining after a period of 12-weeks of training with Mat Pilates on the functional capacity and neuromuscular performance of the knee extensor muscles in older women. Ten older women (62.6 ± 2.6 years; 1.57 ± 0.05 m height; 69.3 ± 9.2 kg; 27.8 kg/m² body mass index) volunteered to participate in this study. The study was divided into three periods: a 4-week control period, followed by 12 weeks of Mat Pilates intervention, and a 6-week detraining period. During the intervention, the results showed significant improvements in functional capacity tests (time up and go, time up stairs, time down stairs, and chair sit-and-reach), rate of torque development, and impulse (p < 0.05). After the detraining period, a decrease was observed in the chair sit-and-reach test (p < 0.05) and contractile impulse at intervals 0–30 and 0–50 ms (p < 0.05). We conclude that a 6-week detraining period after a Mat Pilates training protocol was sufficient to cause declines in the chair sit-and-reach test and in the contractile impulse of the knee extensors in the early phase of the torque-time curve (0–30 and 0–50 ms), but not in the other functional capacity tests and neuromuscular parameters evaluated.     

Normalized muscle strength, aerobic capacity, and walking performance in chronic stroke: a population-based study on the potential for endurance and resistance training

Severinsen K, Jakobsen JK, Overgaard K, Andersen H. Normalized muscle strength, aerobic capacity, and walking performance in chronic stroke: a population-based study on the potential for endurance and resistance training.

Objectives

To assess muscle strength, aerobic capacity, and walking performance compared with normative values in chronic hemiparetic stroke patients and, thereby, to investigate the potential for endurance and resistance training. Second, to study the relations between muscle strength, aerobic capacity, and walking performance using normalized test values.

Design

Population-based, cross-sectional study.

Setting

University hospital, outpatient clinic.

Participants

Patients (N=48) aged 50 to 80 years with reduced muscle strength and walking capacity due to an ischemic stroke 6 to 36 months prior to recruitment.

Interventions

None.

Main Outcome Measures

Peak oxygen consumption (Vo₂peak) and isometric knee extensor muscle strength at the paretic knee were expressed as absolute and normalized values using normative data. The six-minute walk test (6MWT) and the habitual ten-meter walk test (10MWT) were secondary parameters.

Results

Peak Vo₂ was 77% (95% confidence interval [CI], 71–84) of the expected value, and the strength of the paretic knee was 71% (95% CI, 64–78), whereas walking speed (10MWT) was 59% (95% CI, 52–66) and walking distance (6MWT) was 59% (95% CI, 52–67). The normalized Vo₂peak correlated to the normalized 6MWT (r=.58; P<.001) and normalized 10MWT (r=.53; P<.001). Normalized strength of the paretic knee correlated to normalized 6MWT (r=.40; P<.01) and normalized 10MWT (r=.31; P<.05).

Conclusions

Lower extremity muscle strength and aerobic capacity are related to walking performance, which suggests a potential for endurance and resistance training in rehabilitation of walking performance in chronic hemiparesis after stroke. Correction for the influence of age, weight, and height providing normalized values improves the interpretation of severity of impairments and enables comparisons between patients.     

Prehabilitation and rehabilitation for attenuating hindlimb unweighting effects on skeletal muscle and gait in adult and old rats

OBJECTIVE: To compare the effectiveness of no exercise with prehabilitation (exercise before hindlimb unweighting [HLU]) versus rehabilitation (exercise given after HLU) on gait function and skeletal muscle mass and force. DESIGN: Randomized controlled trial. SETTING: Animal laboratory. ANIMALS: Male-specific, pathogen-free Fisher344/Brown Norway rats (N=149). Groups consisted of adult and old controls, HLU, prehabilitation, rehabilitation, natural cage recovery (reloading), and exercise without HLU. INTERVENTIONS: Ten days of general conditioning exercise were given to 6-month-old adult and 30-month-old old rats before or after a week of HLU. MAIN OUTCOME MEASURES: Gait stride length and width; soleus, plantaris, extensor digitorum longus, and peroneus longus mass and peak contractile force; whole gastrocnemius mass; and total protein concentration for the soleus and gastrocnemius. RESULTS: Muscle mass (approximately 30%) and force (24%-36%) declined with age in all muscles studied. In adult rats declines in muscle mass occurred with HLU in the soleus, plantaris, and gastrocnemius. Prehabilitation did not prevent the loss of muscle mass in adult rats. Rehabilitation and natural recovery effectively restored soleus and gastrocnemius muscle mass in adult rats but not soleus peak force. Old rats had a significant 23% HLU effect only on gastrocnemius mass (control, 1670+/-129 mg; HLU, 1274+/-184 mg). Prehabilitation did not prevent the decline in gastrocnemius mass. Rehabilitation in old rats restored gastrocnemius mass to within 13% of control levels. Prehabilitation was effective for preventing and rehabilitation was effective for restoring soleus contractile force in old rats (control, 114+/-9 mg; HLU, 67+/-22 mg; prehabilitation, 106+/-31 mg; rehabilitation, 120+/-26 mg) compared with recovery without exercise (86+/-29 g). A significant reduction in stride length was observed with aging (136+/-18 mm vs 98+/-10 mm), which decreased further with HLU (78+/-14 mm). Prehabilitation attenuated HLU-related reductions in stride length, and rehabilitation was effective for stride length restoration in old rats. CONCLUSIONS: Exercise, particularly rehabilitation, was more effective for old than young rats. Prehabilitation and rehabilitation diminished some of the detrimental effects of HLU on skeletal muscle mass and force and gait function in old rats.     

Reduced task-induced variations in the distribution of activity across back muscle regions in individuals with low back pain

This study investigated change in the distribution of lumbar erector spinae muscle activity and pressure pain sensitivity across the low back in individuals with low back pain (LBP) and healthy controls. Surface electromyographic (EMG) signals were recorded from multiple locations over the lumbar erector spinae muscle with a 13 × 5 grid of electrodes from 19 people with chronic nonspecific LBP and 17 control subjects as they performed a repetitive lifting task. The EMG root mean square (RMS) was computed for each location of the grid to form a map of the EMG amplitude distribution. Pressure pain thresholds (PPT) were recorded before and after the lifting task over a similar area of the back. For the control subjects, the EMG RMS progressively increased more in the caudal region of the lumbar erector spinae during the repetitive task, resulting in a shift in the distribution of muscle activity. In contrast, the distribution of muscle activity remained unaltered in the LBP group despite an overall increase in EMG amplitude. PPT was lower in the LBP group after completion of the repetitive task compared to baseline (average across all locations: pre: 268.0 ± 165.9 kPa; post: 242.0 ± 166.7 kPa), whereas no change in PPT over time was observed for the control group (320.1 ± 162.1 kPa; post: 322.0 ± 179.5 kPa). The results demonstrate that LBP alters the normal adaptation of lumbar erector spinae muscle activity to exercise, which occurs in the presence of exercise-induced hyperalgesia. Reduced variability of muscle activity may have important implications for the provocation and recurrence of LBP due to repetitive tasks.     

运动对大鼠骨骼肌废用性萎缩的恢复及血清雄激素水平的影响

目的探讨在肌肉萎缩和恢复中血清睾酮(ST)水平的变化及不同的锻炼方式对肌萎缩恢复的作用.方法将30只雄性SD大鼠随机分为5组①正常对照组;②外固定3周后即刻宰杀组;③外固定3周后自然恢复3周组;④外固定3周后跑台训练3周组;⑤外固定3周后游泳训练3周组.以放免法测定ST水平.结果固定3周后,即刻宰杀组大鼠ST水平为(0.58±0.24)nmol/L,较正常对照组(6.21±3.51)nmol/L显著下降,两组比较差别有非常显著性意义(P＜0.01);自然恢复组(1.93±0.77)nmol/L和运动组[跑台组(3.01±1.82)nmol/L,游泳组(3.71±2.84)nmol/L]的ST水平均显著高于固定即杀组(0.58±0.24)nmol/L,差别有显著或非常显著性意义(P＜0.05或P＜0.01),但自然恢复组和跑台组仍显著低于对照组水平,差别有显著或非常显著性意义(P＜0.05或P＜0.01),而游泳组已恢复到对照组水平,两组比较差别无显著性意义(P＞0.05);两个运动组之间比较差别无显著性意义(P＞0.05).结论外固定可造成骨骼肌废用性萎缩;解除固定后,萎缩的肌肉可以逐渐恢复,而运动对萎缩肌肉的恢复过程有促进作用,这可能与运动提高机体ST水平有关;游泳锻炼较跑台运动能更有效地提高ST水平.     

The effect of manual pressure release on myofascial trigger points in the upper trapezius muscle

Sustained manual pressure has been advocated as effective treatment for myofascial trigger points (MTrPs). This study aimed to investigate the effect of manual pressure release (MPR) on the pressure sensitivity of latent MTrPs in the upper trapezius muscle using a novel pressure algometer. Subjects (N=37, mean age 23.1±3.2, M=12, F=23) were screened for the presence of latent MTrPs in the upper trapezius muscle (tender band that produced referred pain to the neck and/or head on manual pressure). Subjects were randomly allocated into either treatment (MPR) or control (sham myofascial release) groups. The pressure pain threshold (PPT) was recorded pre- and post-intervention using a digital algometer, consisting of a capacitance sensor attached to the tip of the palpating thumb. There was a significant increase in the mean PPT of MTrPs in the upper trapezius following MPR (P<0.001), but not following the sham treatment. Pressure was monitored and maintained during the application of MPR, and a reduction in perceived pain and significant increase in tolerance to treatment pressure (P<0.001) appeared to be caused by a change in tissue sensitivity, rather than an unintentional reduction of pressure by the examiner. The results suggest that MPR may be an effective therapy for MTrPs in the upper trapezius.     

Gender-specific adaptations of upper trapezius muscle activity to acute nociceptive stimulation

This study examined gender differences in the effect of experimental muscle pain on changes in the relative activation of regions of the upper trapezius muscle during a sustained contraction. Surface electromyographic (EMG) signals were recorded from multiple locations over the upper trapezius muscle with a 10 × 5 grid of electrodes from nine women and nine men during 90° shoulder abduction sustained for 60 s. Measurements were performed before and after the injection of 0.4 ml hypertonic (painful) and isotonic (control) saline into the cranial region of the upper trapezius muscle. The EMG root mean square (RMS) was computed for each location of the grid to form a map of the EMG amplitude distribution. The peak pain intensity following the injection of hypertonic saline was greater for women (numerical rating scale 0–10: women 6.0 ± 2.1, men 4.2 ± 0.9; P < 0.01). For both genders, upper trapezius RMS averaged across the grid decreased following the injection of hypertonic saline (P < 0.0001). Moreover, there was a relatively larger pain-induced decrease in RMS in the cranial region compared to the caudal region of the muscle for both genders. During the non-painful sustained contractions, the EMG RMS progressively increased more in the cranial than the caudal region, for both men and women, due to fatigue. This mechanism was maintained in men but not in women during the painful condition. The results demonstrate that muscle pain alters the normal adaptation of upper trapezius muscle activity to fatigue in women but not in men.     

Therapeutic effect of passive mobilization exercise on improvement of muscle regeneration and prevention of fibrosis after laceration injury of rat

OBJECTIVE: To evaluate the muscle healing effect of passive mobilization exercises after a laceration injury. DESIGN: Randomized controlled trial. SETTING: Basic science laboratory. ANIMALS: Male Sprague-Dawley rats (N=36), age ranging from 8 to 10 weeks and weight ranging from 300 to 400 g. INTERVENTION: The bilateral gastrocnemius muscles were lacerated. The left leg muscles were used as the study groups and the right side was used as the control (lacerated muscles without any treatment, n=8). In the exercise group (n=24), passive mobilization exercise (15 min/d) was performed for 5 days starting from different time points (2, 7, and 14d postlaceration). The decorin group (n=8) was injected with decorin (50 microg at 14d postlaceration), which is a well-known antifibrotic agent. Four animals were used as the normal controls, in which only the muscle strength was evaluated. All the animals were killed 4 weeks after the laceration. MAIN OUTCOME MEASURES: The histologic characterization of muscle regeneration (hematoxylin and eosin staining, number and diameter of the centronucleated, regenerating myofibers), muscle fibrosis (vimentin-positive area, Masson modified trichrome staining positive area), and muscle strength (analysis of fast twitch strength). RESULTS: The level of fibrosis was more than 50% lower in the exercise and decorin groups than in the control (P<.05). The decorin group showed the highest number of regenerated, new myofibers and the highest muscle strength. All of the exercise groups, regardless of the starting time of exercise, also showed significant improvement in regeneration and strength. However, the exercise group starting 14 days after the laceration showed the best results. CONCLUSIONS: Stretching exercises after a muscle laceration injury has a strong antifibrotic effect, as much as a well-known antifibrotic agent, decorin. According to the results, the best time to begin stretching exercises is 14 days after laceration for antifibrosis and muscle regeneration.     

Continuous low-level heat wrap therapy for the prevention and early phase treatment of delayed-onset muscle soreness of the low back: a randomized controlled trial

OBJECTIVE: To evaluate the effects of continuous low-level heat wrap therapy for the prevention and early phase treatment (ie, 0-48 h postexercise) of delayed-onset muscle soreness (DOMS) of the low back. DESIGN: Two prospective randomized controlled trials. SETTING: Outpatient medical facility. PARTICIPANTS: Sixty-seven subjects asymptomatic of back pain and in good general health (mean age, 23.5+/-6.6 y). INTERVENTIONS: Participants performed vigorous eccentric exercise to experimentally induce low back DOMS. Participants were assigned to 1 of 2 substudies (prevention and treatment) and randomized to 1 of 2 treatment groups within each substudy: prevention study (heat wrap, n=17; control [nontarget muscle stretch], n=18) and treatment study (heat wrap, n=16; cold pack, n=16). Interventions were administered 4 hours before and 4 hours after exercise in the prevention study and between hours 18 to 42 postexercise in the treatment study. MAIN OUTCOME MEASURES: To coincide with the expected occurrence of peak symptoms related to exercise-induced low back DOMS, hour 24 postexercise was considered primary. Pain intensity (prevention) and pain relief (treatment) were primary measures, and self-reported physical function and disability were secondary measures. RESULTS: In the prevention study, at hour 24 postexercise, pain intensity, disability, and deficits in self-reported physical function in subjects with the heat wrap were reduced by 47% (P<.001), 52.3% (P=.029), and 45% (P=.013), respectively, compared with the control group. At hour 24 in the treatment study, postexercise, pain relief with the heat wrap was 138% greater (P=.026) than with the cold pack; there were no differences between the groups in changes in self-reported physical function and disability. CONCLUSIONS: In this small study, continuous low-level heat wrap therapy was of significant benefit in the prevention and early phase treatment of low back DOMS.