COMPARISON OF ECCENTRIC AND CONCENTRIC EXERCISE INTERVENTIONS IN ADULTS WITH SUBACROMIAL IMPINGEMENT SYNDROME

Background

Researchers have demonstrated moderate evidence for the use of exercise in the treatment of subacromial impingement syndrome (SAIS). Recent evidence also supports eccentric exercise for patients with lower extremity and wrist tendinopathies. However, only a few investigators have examined the effects of eccentric exercise on patients with rotator cuff tendinopathy.

Purpose

To compare the effectiveness of an eccentric progressive resistance exercise (PRE) intervention to a concentric PRE intervention in adults with SAIS.

Study Design

Randomized Clinical Trial

Methods

Thirty‐four participants with SAIS were randomized into concentric (n = 16, mean age: 48.6 ± 14.6 years) and eccentric (n = 18, mean age: 50.1 ± 16.9 years) exercise groups. Supervised rotator cuff and scapular PRE''s were performed twice a week for eight weeks. A daily home program of shoulder stretching and active range of motion (AROM) exercises was performed by both groups. The outcome measures of the Disabilities of the Arm, Shoulder, and Hand (DASH) score, pain‐free arm scapular plane elevation AROM, pain‐free shoulder abduction and external rotation (ER) strength were assessed at baseline, week five, and week eight of the study.

Results

Four separate 2x3 ANOVAs with repeated measures showed no significant difference in any outcome measure between the two groups over time. However, all participants made significant improvements in all outcome measures from baseline to week five (p <  0.0125). Significant improvements also were found from week five to week eight (p < 0.0125) for all outcome measures except scapular plane elevation AROM.

Conclusion

Both eccentric and concentric PRE programs resulted in improved function, AROM, and strength in patients with SAIS. However, no difference was found between the two exercise modes, suggesting that therapists may use exercises that utilize either exercise mode in their treatment of SAIS.

Level of evidence

Therapy, level 1b     

热应激预处理对离心运动大鼠骨骼肌自由基代谢的影响

背景:研究表明热预处理能够提高肌肉抗损伤的能力,但具体的机制尚不清楚。目的:观察热应激预处理对离心运动大鼠骨骼肌超氧化物歧化酶活性及丙二醛含量的影响。方法:雄性Wistar大鼠随机分为对照组、离心运动组、预热应激+离心运动组。热应激温度为43℃,时间约35min。采用-16°下坡跑台跑做大负荷间歇性离心运动,跑速为26.8m/min,运动5min,间歇1min,共进行10组。分别于运动前1h、运动后1,24,48h取大鼠腓肠肌,采用硫代巴比妥酸法测定大鼠丙二醛含量,黄嘌呤氧化酶法测定超氧化物歧化酶活性。结果与结论:与对照组比较,离心运动组大鼠腓肠肌丙二醛含量显著增高(P<0.05),并随运动后时间的延长逐渐升高,超氧化物歧化酶活性随运动后时间的延长显著降低(P<0.05)。与离心运动组比较,预热应激+离心运动组大鼠腓肠肌超氧化物歧化酶活性显著增高(P<0.05),丙二醛含量显著降低(P<0.05)。说明热应激预处理可增强骨骼肌超氧化物歧化酶活性,降低丙二醛含量,对离心运动损伤有保护作用。     

Comparison of Lower Limb Muscle Activity during Eccentric and Concentric Exercises in Runners with Achilles Tendinopathy

[Purpose] This study aimed to identify changes in muscle activation by comparing muscle activities of the affected side (AS) and non-affected side (NAS) during eccentric and concentric exercises in runners with unilateral Achilles tendinopathy. [Subjects] The study included 18 participants consisting of men and women with chronic Achilles tendinopathy in a single leg who had more than 1 year of running experience. [Methods] All subjects performed concentric and eccentric exercise with the Achilles tendon moving from full plantar flexion to full dorsiflexion for 8 seconds, and electromyography data was obtained. [Results] All muscles examined showed a significant increase in %maximal voluntary contraction (MVC) with concentric exercise compared with eccentric exercise. Compared with the NAS, the AS showed significant increases in %MVC of the rectus femoris, tibialis anterior, and lateral gastrocnemius. All interaction effects of exercise methods and injuries showed statistically significant changes. [Conclusion] Runners with Achilles tendinopathy show increases in medial gastrocnemius activity when performing eccentric exercise.Key words: Achilles tendinopathy, Eccentric exercise, Electromyography     

THE ROLE AND IMPLEMENTATION OF ECCENTRIC TRAINING IN ATHLETIC REHABILITATION: TENDINOPATHY,HAMSTRING STRAINS,AND ACL RECONSTRUCTION

The benefits and proposed physiological mechanisms of eccentric exercise have previously been elucidated and eccentric exercise has been used for well over seventy years. Traditionally, eccentric exercise has been used as a regular component of strength training. However, in recent years, eccentric exercise has been used in rehabilitation to manage a host of conditions. Of note, there is evidence in the literature supporting eccentric exercise for the rehabilitation of tendinopathies, muscle strains, and in anterior cruciate ligament (ACL) rehabilitation. The purpose of this Clinical Commentary is to discuss the physiologic mechanism of eccentric exercise as well as to review the literature regarding the utilization of eccentric training during rehabilitation. A secondary purpose of this commentary is to provide the reader with a framework for the implementation of eccentric training during rehabilitation of tendinopathies, muscle strains, and after ACL reconstruction.     

Mechanical and magnetic resonance imaging changes following eccentric or concentric exertions

BACKGROUND: Prior work has shown that changes in mechanical parameters and magnetic resonance imaging parameters occur following submaximal eccentric activity but it is unclear whether similar changes occur following submaximal concentric activity. This study compared mechanical response parameters and MRI relaxation parameters following submaximal concentric or eccentric exertions. METHODS: This single site, randomized study investigated in vivo changes in human upper limb dynamic mechanical properties following exposure to short term repetitive submaximal eccentric or concentric exertions. Eighteen subjects were assigned to either an eccentric or concentric group and exercised for 30 min at 50% of isometric forearm maximum voluntary contraction. Changes in strength, symptom intensity, magnetic resonance imaging T2 relaxation measurements, which are indicative of edema, and dynamic mechanical parameters (stiffness, effective mass, and damping) were ascertained prior to exercise, 1h after, and 24h later. FINDINGS: Strength decreased following exercise (P<0.01), however only the eccentric exercise group exhibited a reduction in mechanical stiffness (55%, P<0.01) and damping (31%, P<0.05), and an increase (17%, P<0.05) in magnetic resonance imaging T2 relaxation time. INTERPRETATION: The changes in mechanical parameters and magnetic resonance imaging findings following repetitive submaximal eccentric activity could negatively impact the ability of the arm to react to rapid forceful loading during repetitive industrial work activities and may result in increased strain on the upper limb. Similar changes were not observed following concentric exercise.     

FOREARM POSITION MATTERS DURING ECCENTRIC SHOULDER EXERCISES: AN EMG RECRUITMENT STUDY WITH IMPLICATIONS FOR REHABILITATION

Background:Eccentric exercise has demonstrated great utility in the rehabilitation of various shoulder pathologies. Research on the electromyographic (EMG) activity of the shoulder musculature during these activities is limited, however. Furthermore, no studies have observed how forearm positioning during exercise affects EMG output.Purpose/Hypothesis:The purpose was to examine the degree of specific muscle recruitment among commonly used eccentric exercises in rehabilitation of the upper extremity and shoulder. Secondarily, the authors hypothesized that different hand/forearm positions would alter EMG activity within the targeted musculature during a given exercise.Study Design:Prospective cross-sectional observation of EMG analysisMethods:This study analyzed surface EMG data obtained from 10 healthy individuals during five eccentric exercises of the dominant extremity, performed in a randomized order: side-lying eccentric horizontal abduction (SL ER), half-kneeling weighted ball decelerations (BALL DC), seated eccentric external rotation in scaption (STD ER), standing eccentric external rotation at 0deg (STND ER), supine eccentric external rotation at 90deg (SUP ER). Each exercise was performed with two to three forearm position variants commonly used in clinical environments: neutral, pronation, and/or supination. EMG data were collected from the upper trapezius, infraspinatus, teres minor, latissimus dorsi, and anterior/middle/posterior deltoid. Data were analyzed for each individual exercise and within each muscle using a mixed-model ANOVA repeated across forearm position. Significant interactions were followed by a Bonferroni post-hoc test for pairwise comparisons. Effect size was calculated for all significant pairwise comparisons using a Cohen''s d statistic.Results:Significant differences in EMG activity for the selected musculature exist between forearm positions for four of the five exercises and Cohen''s d effect sizes 0.178 – 1.159.Conclusion:Specific eccentric shoulder exercises activate muscles of the shoulder complex differently based on forearm positioning.Level of Evidence:Level 2     

热应激预处理对离心运动大鼠骨骼肌自由基代谢的影响

背景：研究表明热预处理能够提高肌肉抗损伤的能力,但具体的机制尚不清楚。目的：观察热应激预处理对离心运动大鼠骨骼肌超氧化物歧化酶活性及丙二醛含量的影响。方法：雄性Wistar大鼠随机分为对照组、离心运动组、预热应激＋离心运动组。热应激温度为43℃,时间约35min。采用-16°下坡跑台跑做大负荷间歇性离心运动,跑速为26.8m/min,运动5min,间歇1min,共进行10组。分别于运动前1h、运动后1,24,48h取大鼠腓肠肌,采用硫代巴比妥酸法测定大鼠丙二醛含量,黄嘌呤氧化酶法测定超氧化物歧化酶活性。结果与结论：与对照组比较,离心运动组大鼠腓肠肌丙二醛含量显著增高（P〈0.05）,并随运动后时间的延长逐渐升高,超氧化物歧化酶活性随运动后时间的延长显著降低（P〈0.05）。与离心运动组比较,预热应激＋离心运动组大鼠腓肠肌超氧化物歧化酶活性显著增高（P〈0.05）,丙二醛含量显著降低（P〈0.05）。说明热应激预处理可增强骨骼肌超氧化物歧化酶活性,降低丙二醛含量,对离心运动损伤有保护作用。     

Selective Breeding for a Behavioral Trait Changes Digit Ratio

The ratio of the length of the second digit (index finger) divided by the fourth digit (ring finger) tends to be lower in men than in women. This 2D4D digit ratio is often used as a proxy for prenatal androgen exposure in studies of human health and behavior. For example, 2D4D ratio is lower (i.e. more “masculinized”) in both men and women of greater physical fitness and/or sporting ability. Lab mice have also shown variation in 2D4D as a function of uterine environment, and mouse digit ratios seem also to correlate with behavioral traits, including daily activity levels. Selective breeding for increased rates of voluntary exercise (wheel running) in four lines of mice has caused correlated increases in aerobic exercise capacity, circulating corticosterone level, and predatory aggression. Here, we show that this selection regime has also increased 2D4D. This apparent “feminization” in mice is opposite to the relationship seen between 2D4D and physical fitness in human beings. The present results are difficult to reconcile with the notion that 2D4D is an effective proxy for prenatal androgen exposure; instead, it may more accurately reflect effects of glucocorticoids, or other factors that regulate any of many genes.     

Muscle pain induced by novel eccentric exercise does not disturb the sleep of normal young men

This experiment sought to determine if delayed-onset muscle pain following novel eccentric exercise would disrupt sleep. Nine young adult men performed eccentric exercise and, during a separate week, concentric exercise consisting of 8 sets of 10 repetitions at 80% of 1-repetition maximum for 3 muscle groups. Sleep was assessed polysomnographically the night before and 2 nights following the exercise bouts. Muscle pain intensity in the biceps, triceps, and quadriceps muscle groups was significantly increased following eccentric exercise (all P <.02), and upper arm range of motion was significantly decreased following eccentric exercise (F = 19.19; df [degrees of freedom] = 2,16; P <.0001). A Condition-by-Trial interaction was observed for stage 1 sleep (F = 6.91; df = 2,16; P =.007), and minutes of stage 1 sleep were reduced following eccentric exercise and increased following concentric exercise. In general, however, the hypothesized sleep disruptions following eccentric exercise were not observed. It is concluded that delayed onset muscle pain induced by novel eccentric exercise does not disturb the sleep of normal young men.     

Correction: MOF-5 derived carbon as material for CO2 adsorption

Correction for ‘MOF-5 derived carbon as material for CO₂ absorption’ by Wojciech Kukulka et al., RSC Adv., 2019, 9, 18527–18537.

The authors regret that the title shown in the original article and several sentences were incorrect due to the use of the word “absorption” in place of “adsorption”. The correct title is as shown above and all instances of “absorption” in the text should be “adsorption”. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

CURRENT CONCEPTS OF MUSCLE AND TENDON ADAPTATION TO STRENGTH AND CONDITIONING

Injuries to the muscle and/or associated tendon(s) are common clinical entities treated by sports physical therapists and other rehabilitation professionals. Therapeutic exercise is a primary treatment modality for muscle and/or tendon injuries; however, the therapeutic exercise strategies should not be applied in a “one‐size‐fits‐all approach”. To optimize an athlete''s rehabilitation or performance, one must be able to construct resistance training programs accounting for the type of injury, the stage of healing, the functional and architectural requirements for the muscle and tendon, and the long‐term goals for that patient. The purpose of this clinical commentary is to review the muscular and tendinous adaptations associated with strength training, link training adaptations and resistance training principles for the athlete recovering from an injury, and illustrate the application of evidence‐based resistance training for patients with a tendinopathy.

Level of Evidence

5     

Assessment of spine pain presence in children and young persons studying in ballet schools

[Purpose] Spine disorders affect various sections of the spine and have a variety of causes. Most pain occurs in the lumbo-sacral and cervical regions. Dance is associated with exercise. High levels of physical activity predispose to back pain occurrence. [Subjects and Methods] The subjects were 237 ballet learners; 80 children (primary school level), mean age 11.24±0.77, mean of years of training ballet 2.14±0.74; 93 students (junior high school level), mean age 14.01±0.84, mean of years of learning ballet 4.64±1.24; 64 students (high school) mean age 17.01±0.77, mean of years of learning ballet 7.47±1.54. Numeric rating scale was used to determine spine pain. [Results] Feelings of pain were analyzed on the basis of “now” and “before” between levels education by using point statistics and statistical tests to compare groups. “Now” exhibited weaker back pain feelings than “before” at all the education levels. There were statistically significant differences in pain feeling for “before” (at any time of learning) and “now” (the day of survey). [Conclusion] All patients reported pain “before” and “now” in cervical, thoracic and lumbar spine. At all levels of education there were statistically significant differences in feelings of pain between “before” and “now”.Key words: Back pain, Ballet     

The effects of continuous external compression on delayed-onset muscle soreness (DOMS)

Delayed-onset muscle soreness (DOMS) is a sensation of soreness that develops 24–48 hr after intense unaccustomed exercise. Clinical characteristics of DOMS include local tissue edema, decreased muscle strength, and decreased range of motion. Although controversial, some research has implicated swelling as a cause or contributor to soreness. We designed this study to determine the effects of continuous external compression on swelling resulting from eccentric contraction and the accompanying clinical characteristics of DOMS. Twenty-three healthy college students (16 females, 7 males; X age=26.0 years) completed 70 maximal eccentric contractions of the elbow flexors to induce soreness and then received random assignment to either a control or a compression sleeve group. The compression sleeve group wore an elastic compression sleeve on the exercised arm, extending from the deltoid insertion to the wrist, throughout the study. We obtained measures of subjective soreness, range of motion (ROM), circumference, arm volume, and isokinetic peak torque for both groups immediately before exercise and 10 min and 24, 48, and 72 hr after exercise. No significant differences were present between groups at any time reference for any of the dependent variables. Soreness peaked at 48 hr and then began to decline. Circumference and volume measurements increased over time with the greatest difference occurring 72 hr postexercise. Subject's ROM and peak torque decreased immediately following exercise and continued to be lower than baseline during the next 72 hr. Continuous external compression, which prior research has shown to be an effective treatment of edema resulting from a variety of acute injuries, was not effective in reducing the edema associated with DOMS, nor was it effective in reducing soreness, strength loss, or ROM loss as a result of DOMS in elbow flexors. Therefore, the clinical use of compression garments in treating DOMS in upper extremities is questionable.     

A Preseason Training Program With the Nordic Hamstring Exercise Increases Eccentric Knee Flexor Strength and Fascicle Length in Professional Female Soccer Players

BackgroundTraining programs that include the Nordic hamstring exercise (NHE) have been shown to increase eccentric knee flexor strength and biceps femoris fascicle length in male athletes. However, the effect of NHE on female athletes remains unknown.PurposeTo investigate the collective and individual responses of professional female soccer players engaged in a preseason training program with the NHE regarding eccentric knee flexor strength and biceps femoris long head fascicle length.Study DesignQuasi-experimental study.MethodsSixteen amateur female soccer players (without a NHE training routine) were evaluated 8-weeks apart to: (1) assess reliability of eccentric knee flexor strength and biceps femoris fascicle length measures; and (2) determine the typical error of measures that would be used to discriminate training responders and non-responders. The NHE training group had 17 professional female soccer players who performed an 8-week training program with the NHE during preseason. Within-group analysis was performed with paired sample t-tests (pre- vs. post-training), and individual responses were determined using the typical error criteria.ResultsThe non-trained group’s data demonstrated that measures of strength (ICC=0.82-0.87, typical error = 12-13 N) and fascicle length (ICC=0.92-0.97; typical error = 0.19-0.38 cm) were reliable. In the NHE training group, both limbs increased the eccentric knee flexor strength (~13%; ES=0.74-0.82) and the biceps femoris fascicle length (~6%; ES=0.44-0.65). Twelve players (~71%) were considered responders to the NHE training program for the eccentric knee flexor strength, while eight athletes (~47%) were responders for the biceps femoris fascicle length.ConclusionThe 8-week preseason training program with the NHE increased both eccentric knee flexor strength and biceps femoris fascicle length in professional female soccer players. More than two-thirds of players demonstrated a meaningful increase in eccentric strength, while nearly half achieved consistent fascicle length increases with the NHE training.     

Induction of Muscle Hypertrophy in Rats through Low Intensity Eccentric Contraction

[Purpose] The purpose of this study was to examine whether a low intensity exercise using an eccentric contraction would result in skeletal muscle hypertrophy in rats. [Subjects and Methods] Eighteen female Wistar rats were used in this study. The rats were randomly divided into three groups. The control group performed no exercise. The level group ran on a treadmill on a 0° incline. The downhill group ran on a treadmill on a −16° incline. The two exercise groups ran on a treadmill at 16 m/min for 90 minutes, once every three days for a total of twenty sessions. [Results] The muscle wet weights, the relative weight ratios, and the muscle fiber cross-section minor axes of the downhill group were significantly larger than those of the control and level groups. There were no differences in the muscle wet weights, the relative weight ratios, and the muscle fiber cross-section minor axes between the control group and the level group. [Conclusion] The stimulation from the low intensity eccentric contraction may have produced enough mechanical stress to induce muscle hypertrophy without the over-stressing that might have produced muscle fiber damage. These results indicate that this technique may be an effective method of inducing hypertrophy in skeletal muscle.Key words: Eccentric contraction, Low intensity exercise, Muscle hypertrophy     

Factors associated with falls in community-dwelling older adults: an analysis based on subscales of the frailty screening index

[Purpose] We aimed to obtain new findings by investigating the relationship between the presence or absence of falls and the results from the Frailty Screening Index (FSI), which can be easily carried out. [Participants and Methods] A total of 780 community-dwelling older adults (age ≥65 years) were classified based on whether they had fallen in the past year as those who had fallen at least once (fall group), and those who had not (non-fall group). We compared the study groups using sub-items of the FSI to extract more specific fall-related factors. The FSI is a questionnaire that comprises five items with simple ‘yes/no’ responses. [Results] The following three out of five sub-items of the FSI were extracted as fall-related factors: 1) “no” to the question, “Do you do physical exercise, like walking, at least once a week?”; 2) “yes” to the question, “Do you think you walk slower than before?”; and 3) “yes” to the question, “Have you felt tired for no reason (in the past two weeks)?” [Conclusion] The study results suggest the significance of paying attention to participant responses to the sub-items on the FSI, instead of merely determining their frailty risk based on their total score.Key words: Falls, Frailty, Community-dwelling older adults