The effects of training, immobilization and remobilization on musculoskeletal tissue

Short-time recovery skeletal muscle from dexamethasone-induced atrophy and weakness in old female rats

BACKGROUND

Several pathological conditions (atrophy, dystrophy, spasticity, inflammation) can change muscle biomechanical parameters. Our previous works have shown that dexamethasone treatment changes skeletal muscle tone, stiffness, elasticity. Exercise training may oppose the side effects observed during dexamethasone treatment. The purpose of this study was to examine the changes in biomechanical parameters (tone, stiffness, elasticity) of skeletal muscle occurring during dexamethasone treatment and subsequent short-time recovery from glucocorticoid-induced muscle atrophy and weakness, as well as the effect of mild therapeutic exercise.

METHODS

17 old female rats, aged 22 months were used in this study. The hand-held and non-invasive device (MyotonPRO, Myoton Ltd., Tallinn, Estonia) was used to study changes in biomechanical properties of muscle. Additionally, body and muscle mass, hind limb grip strength were assessed.

FINDINGS

Results showed that dexamethasone treatment alters muscle tone, stiffness and elasticity. During 20-day recovery period all measured parameters gradually improved towards the average baseline, however, remaining significantly lower than these values. The body and muscle mass, hind limb grip strength of the rats decreased considerably in the groups that received glucocorticoids. After 20 days of recovery, hind limb grip strength of the animals was slightly lower than the baseline value and mild therapeutic exercise had a slight but not significant effect on hind limb grip strength. Biomechanical parameters improved during the recovery period, but only dynamic stiffness and decrement retuned to baseline value.

INTERPRETATION

The study results show that monitoring muscle biomechanical parameters allows to assess the recovery of atrophied muscle from steroid myopathy.

Wing-feather loss in white-feathered laying hens decreases pectoralis thickness but does not increase risk of keel bone fracture

Feather loss in domestic chickens can occur due to wear and tear, disease or bird-to-bird pecking. Flight feather loss may decrease wing use, cause pectoral muscle loss and adversely impact the keel bone to which these muscles anchor. Feather loss and muscle weakness are hypothesized risk factors for keel bone fractures that are reported in up to 98% of chickens. We used ultrasound to measure changes in pectoral muscle thickness and X-rays to assess keel bone fracture prevalence following symmetric clipping of primary and secondary feathers in white- and brown-feathered birds. Four and six weeks after flight feather clipping, pectoralis thickness decreased by approximately 5%, while lower leg thickness increased by approximately 5% in white-feathered birds. This pectoralis thickness decrease may reflect wing disuse followed by muscle atrophy, while the increased leg thickness may reflect increased bipedal locomotion. The lack of effect on muscle thickness in brown-feathered hens was probably due to their decreased tendency for aerial locomotion. Finally, pectoralis thickness was not associated with keel bone fractures in either white- or brown-feathered birds. This suggests that the white-feathered strain was more sensitive to feather loss. Future prevention strategies should focus on birds most susceptible to muscle loss associated with flight feather damage.

Recovery of the medial gastrocnemius muscle after calcaneus fracture differs between contractile and elastic components

BACKGROUND

Calcaneal fractures result in severe functional impairments and walking restrictions. Postoperative evaluation mainly focusses on the restoration of calcaneal anatomy while ankle plantar flexor insufficiency remains largely neglected. This study aims to investigate biomechanical and morphologic adaptions of elastic and contractile components of the gastrocnemius medialis after unilateral calcaneal fracture.

METHODS

20 Patients (BMI: 27.6 ± 3.1 kgm^-2, Age: 50 ± 12 years) were measured using gait analysis and portable ultrasound over a follow-up of three, six and twelve months after surgery. Data comparison was performed using 20 matched healthy controls (BMI: 26.2 ± 2.9 kgm^-2, Age: 48 ± 11 years). Static and dynamic behavior of the gastrocnemius muscle tendon unit, muscle fascicle and the serial-elastic element as well ankle joint kinematics and kinetics were analyzed.

FINDINGS

Within patients, a significant (p < 0.05) increase in fascicle length (by 67%) during single support and a decrease of serial elastic element shortening (by 20%) during push off was found between three and twelve months follow-up comparisons. Patients showed differences for fascicle lengthening and pennation angle increase during single support after three and six months compared to healthy controls. A smaller shortening of the serial-elastic element (by 29%) and muscle-tendon unit (by 16%) persisted even for the twelve month comparisons.

INTERPRETATION

Patients with calcaneal fracture showed an incomplete restoration of the medial gastrocnemius dynamic morphological behavior. While muscle fascicle contraction almost recovered, the serial elastic component still showed restrictions regarding its shortening behavior. Limited foot mobility and plantarflexor strength as well as lowered responsiveness of elastic tissues to mechanical loading are regarded as key mechanisms.

Positive Effect of Kinesiotape on 1 km Run Performance in University-Level Males: A Cross-Sectional Study

Introduction: The kinesiotape (KT) method is used to exert a positive effect on muscular, nervous, and organ systems, recognizing the importance of muscle movement. It is widely applied in runners for performance enhancement. However, there is no scientific background to use it as a running speed modulator. Objectives: The purpose of this study was to verify the KT effect on running performance in university-level students while speed is considered. The 1 km run and 40 m shuttle run were investigated. Participants were highly motivated to run as fast as possible since the research was part of the graded fitness test. Students wanted to perform as well as possible to get good marks. Methods: A total of 150 students aged 19.93 ± 0.85 with BMIs of 26.93 ± 0.98 were randomly distributed to the experimental (EG), placebo (PG), and control group (CG). In the EG, 50 students were measured pre-test (no KT) and post-test (KT applied). In the PG, 50 students were measured the same way using the placebo application post-test. In the CG, 50 students were measured without any intervention pre-test or post-test. The application area was the triceps surae muscle bilaterally with KT tension of 75%. The Kruskal−Wallis test and repeated measures ANOVA were used for analysis with a 0.05 level of significance. Results: A statistically significant group effect was reported in the EG (<0.05) in the 1 km run discipline. The time results obtained were significantly shorter than in the PG and the CG. There was no statistically significant difference (0.717) reported in the 40 m shuttle run discipline between the groups. Conclusions: Applying KT with a tension of 75% on the triceps surae muscle bilaterally might be useful to increase the performance of medium or longer distance runs but may not be effective in improving sprinting ability. We recommend applying the KT in the overall muscle and tendon area with a tension of 75% if there is a focus on performance enhancement.

Conservative treatment of Achilles tendon partial tear in a futsal player: A case report

Background and purpose: Achilles tendon is the most commonly injured part in the lower limb, especially in athletes. Treatment options for Achilles tendinopathy and total rupture are well described; however, there is a lack of information regarding treatment protocols for partial tears. Thus, the purpose of this case report was to describe the examination, intervention and outcomes of patient who suffered an acute Achilles tendon partial tear. Case description: A case is described here, in which the diagnosis of Achilles tendon partial tear was based on both magnetic resonance imaging and physical evaluation. Both the patient and the physical therapy team opted for non-surgical treatment. A 12-week course of conservative treatment including exercise, tendon loading, electrical stimulation, and photobiomodulation is described. Outcomes: Ankle dorsiflexion range of motion and hop tests. Discussion: This case report demonstrated that non-surgical treatment for Achilles tendon partial tear was effective for this patient and enabled the athlete to return to pre-injury levels of activity 6 months following the injury.

Early Incorporation of an Evidence-Based Aquatic-Assisted Approach to Arthroscopic Rotator Cuff Repair Rehabilitation: Prospective Case Study

BACKGROUND AND PURPOSE

Both traditional and progressive rotator cuff repair rehabilitation protocols often delay active motion of the shoulder for 6 weeks or more. The early inclusion of a comprehensive aquatic-assisted exercise program presents a unique approach to postoperative management. The purpose of this case study is to describe a comprehensive evidence-based, aquatic-assisted rehabilitation program following arthroscopic rotator cuff repair.

CASE DESCRIPTION

A 73-year-old woman with a nonretracted, medium-size, full-thickness tear (2.5 cm) of the supraspinatus tendon underwent arthroscopic rotator cuff repair and was referred for postoperative physical therapy. The rehabilitation program was initiated at 2 weeks postoperatively and consisted of concurrent land- and aquatic-based interventions over 6 weeks for a total of 18 physical therapy visits.

OUTCOMES

Improvements were made in all 5 patient-reported outcome measures that were recorded weekly over the course of care. Improvements reached or exceeded minimal detectable change levels for the Shoulder Pain and Disability Index and the Penn Shoulder Score. Her numeric pain rating scale score at rest decreased from 4/10 at the initial evaluation to 2/10 at 8 weeks postoperatively and with activity decreased from 9/10 to 6/10. Shoulder strength and range of motion values also exhibited improvement over the course of care. No adverse events occurred during the case study.

DISCUSSION

This case study illustrates the safe inclusion of low-stress aquatic exercises as an early adjunct to traditional land-based rotator cuff repair rehabilitation programs in small- to medium-size repairs. Further studies are needed to determine the long-term effectiveness of adding aquatic therapy to traditional postoperative programs.

Early loading in physiotherapy treatment after full-thickness rotator cuff repair: a prospective randomized pilot-study with a two-year follow-up

Objective: To describe the clinical changes following two different physiotherapy treatment protocols after rotator cuff repair.

Design: A prospective, randomized pilot study with a two-year follow-up.

Subjects: Five women and nine men, 55 (40—64) years old, were included.

Intervention: The progressive group (n = 7) started with dynamic, specific muscle activation of the rotator cuff the day after surgery as well as passive range of motion. After four weeks of immobilization the loading to the rotator cuff increased and in a progressive manner throughout the rehabilitation. In the traditional group (n = 7) the rotator cuff was protected from loading. Patients were immobilized for six weeks and started with passive range of motion the day after surgery. No specific exercises to the rotator cuff were introduced during this period.

Main measures: A clinical evaluation was made preoperatively, 3, 6, 12 and 24 months after surgery. Pain rating during activity and at rest, patient satisfaction, active range of motion and muscle strength, Constant score, hand in neck, hand in back and pour out of a pot, as well as Functional Index of the Shoulder were used.

Results: At two years follow-up, the progressive group and traditional group scored pain during activity visual analogue scale (VAS) 2/0 mm and pain at rest 0/0 mm, respectively. The groups attained 170/175° in active abduction in standing and 70/90° in passive external rotation while lying in supine. Using Constant score, the groups attained 82/77 points respectively.

Conclusion: The present study showed that the progressive protocol produced no adverse effects compared with the traditional protocol.

Histomorphometric analysis of the response of rat skeletal muscle to swimming, immobilization and rehabilitation

The objective of the present study was to determine to what extent, if any, swimming training applied before immobilization in a cast interferes with the rehabilitation process in rat muscles. Female Wistar rats, mean weight 260.52 +/- 16.26 g, were divided into 4 groups of 6 rats each: control, 6 weeks under baseline conditions; trained, swimming training for 6 weeks; trained-immobilized, swimming training for 6 weeks and then immobilized for 1 week; trained-immobilized-rehabilitated, swimming training for 6 weeks, immobilized for 1 week and then remobilized with swimming for 2 weeks. The animals were then sacrificed and the soleus and tibialis anterior muscles were dissected, frozen in liquid nitrogen and processed histochemically (H&E and mATPase). Data were analyzed statistically by the mixed effects linear model (P < 0.05). Cytoarchitectural changes such as degenerative characteristics in the immobilized group and regenerative characteristics such as centralized nucleus, fiber size variation and cell fragmentation in the groups submitted to swimming were more significant in the soleus muscle. The diameters of the lesser soleus type 1 and type 2A fibers were significantly reduced in the trained-immobilized group compared to the trained group (P < 0.001). In the tibialis anterior, there was an increase in the number of type 2B fibers and a reduction in type 2A fibers when trained-immobilized rats were compared to trained rats (P < 0.001). In trained-immobilized-rehabilitated rats, there was a reduction in type 2B fibers and an increase in type 2A fibers compared to trained-immobilized rats (P < 0.009). We concluded that swimming training did not minimize the deleterious effects of immobilization on the muscles studied and that remobilization did not favor tissue re-adaptation.

Effect of foot and ankle immobilization on leg and thigh muscles' volume and morphology: a case study using magnetic resonance imaging

Our aim was to determine the time course of any changes in muscle volume and shape in the lower limbs following immobilization. A healthy young woman (29 years) had suffered a fracture of the fifth metatarsal of the right foot. MRI scanning of her right thigh and calf muscles had been performed 1 month before the injury (Pre) during a scan initially planned as a teaching tool, 2 days following a 4-week immobilization period (Post), and after a 2-month recovery period (Post+2). The results show muscle volume decrements in the triceps surae (TS), quadriceps (Quad), and hamstring (Ham) of 21.9%, 24.1%, and 6.5%, respectively, between the Pre and Post measurements. At Post+2, the Quad and TS muscle volumes were still 5.2% and 9.5% lower, compared with the Pre data. The Ham muscle volume, however, was 2.7% greater than at the Pre phase. Following recovery, the increase in individual TS muscles volume was limited to both proximal and medial (with respect to the knee joint) segments of the muscles. These results indicate very substantial and rapid losses in muscle volumes, both proximally and distally to the immobilization site. The results also show that recovery is far from complete up to 2 months post cast removal. The results have implications for the requirements for rehabilitation for orthopedic patients.

Early activation or a more protective regime after arthroscopic subacromial decompression — a description of clinical changes with two different physiotherapy treatment protocols — a prospective, randomized pilot study with a two-year follow-up

Objectives: To describe clinical changes with two protocols of physiotherapy following arthroscopic subacromial decompression (ASD) over two years. Reliability of Functional Index of the Shoulder was performed.

Design: A prospective, randomized pilot study, within-subject design.

Subjects: Thirty-four shoulders (13 women), mean age 46 (SD 7) years with primary shoulder impingement, listed for arthroscopic subacromial decompression.

Interventions: The traditional group (n = 20) started with active assisted range of motion exercises on the day of surgery, dynamic exercises for the rotator cuff after six weeks and strengthening exercises after eight weeks. The progressive group (n = 14) started active assisted range of motion and dynamic exercises for the rotator cuff on the day of surgery. Strengthening exercises started after six weeks.

Main measures: A clinical evaluation was made preoperatively, six weeks, three, six, 12 and 24 months after surgery. Pain, patient satisfaction, active range of motion and muscular strength were evaluated. Shoulder function was evaluated using Constant score, Hand in neck, Pour out of a pot and Functional Index of the Shoulder.

Results: Both groups showed significant improvements in pain during activity and at rest, in range of motion in extension and abduction, in strength of external rotation and in function. There were no clinical differences in changes between groups. Most patients were pain-free from six months. After two years, the majority of patients achieved ≥160°in flexion, ≥175°in abduction and 80°in external rotation, the traditional achieved 67 and the progressive group 87 with Constant score.

Conclusions: Early activation using a comprehensive, well-defined and controlled physiotherapy protocol can be used safely after arthroscopic subacromial decompression.

Biomechanical effects of immobilization and rehabilitation on the skeletal muscle of trained and sedentary rats

Because of the scarcity of information about the comparison of training to sedentarism beforehand immobilization and rehabilitation through muscle mechanical properties, the present work investigates this theme. Seventy rats were divided into 7 groups: 1-control (C); 2-trained (T); 3-sedentary (S); 4-trained and immobilized (TI); 5-sedentary and immobilized (SI); 6-trained, immobilized and rehabilitated (TIR); 7-sedentary, immobilized and rehabilitated (SIR).

INTERVENTIONS

Swimming training; Sedentarism (reduced size cages); Cast immobilization (pelvic limb) and water rehabilitation. Load at the limit of proportionality (LLP), maximum limit load (MLL) and stiffness (St) were the mechanical properties determined after a mechanical test of traction of the gastrocnemius. The training improved all mechanical properties when compared to sedentarism. After immobilization, LLP and MLL were reduced in TI and SI. However, there was no difference in St between C and TI. Additionally, TI showed improved MLL when compared to SI. The comparison of TI and TIR showed significant melioration in all properties after remobilization. SIR showed an improvement only in MLL when compared to SI. Significant melioration in LLP and St was observed in TIR compared to SIR. We demonstrated that the training before immobilization and rehabilitation had a positive effect on the muscle mechanical behavior compared to sedentarism. This analysis is of fundamental importance because it helps characterize the muscle tissue under different functional demands.

Aftertreatment of malleolar fractures following ORIF -- functional compared to protected functional in a vacuum-stabilized orthesis: a randomized controlled trial

In a monocenter randomized controlled trial, 45 patients with isolated malleolar fracture type OTA/AO 44 A1-B2 undergoing ORIF were allocated randomly to a postoperative treatment either with a vacuum-stabilized orthesis with prescribed full weight bearing after the second week (23 patients) (orthesis group -- OG) or with functional aftertreatment with partial weight bearing of 15 kg for 6 weeks (22 patients) (control group -- CG). Outcomes were compared at 6- and 10-week follow-up examinations. The Olerud and Molander ankle (OMA) score, ankle swelling, usage of crutches, range of motion, Short Form 12, patient-reported visual analogue scales (VAS) (pain, comfort, walking confidence) and time to return to work were evaluated. All patients of OG showed reduced swelling at discharge. The median OMA scores after 6 weeks were 42 and 42.5 (p = 0.46) and after 10 weeks 69 and 72 (p = 0.55) in the OG and CG, respectively. The time to achieve secure walking capacity was reduced by 1 day (p = 0.03) in the OG. After ORIF of simple malleolar fractures, patients with a vacuum-stabilized orthesis can bear full weight 2 weeks postoperatively. This group experienced no adverse events. Postoperative swelling was significantly reduced and of the ability to walk on stairs confidently was shorter as compared to a functional aftertreatment without any external stabilization of the ankle.

Evaluation of a physiotherapeutic treatment intervention in "Bell's" facial palsy

The aim of this study was to evaluate a physiotherapeutic treatment intervention in Bell's palsy. A consecutive series of nine patients with Bell's palsy participated in the study. The subjects were enrolled 4-21 weeks after the onset of facial paralysis. The study had a single subject experimental design with a baseline period of 2-6 weeks and a treatment period of 26-42 weeks. The patients were evaluated using a facial grading score, a paresis index and a written questionnaire created for this study. Every patient was taught to perform an exercise program twice daily, including movements of the muscles surrounding the mouth, nose, eyes and forehead. All the patients improved in terms of symmetry at rest, movement and function. In conclusion, patients with remaining symptoms of Bell's palsy appear to experience positive effects from a specific training program. A larger study, however, is needed to fully evaluate the treatment.

Basic science and clinical studies coincide: active treatment approach is needed after a sports injury

The basic response to injury at the tissue level is well known and consists of acute inflammatory phase, proliferative phase, and maturation and remodeling phase. Knowing these phases, the treatment and rehabilitation program of athletes' acute musculoskeletal injuries should use a short period of immobilization followed by controlled and progressive mobilization. Both experimental and clinical trials have given systematic and convincing evidence that this program is superior to immobilization - a good example where basic science and clinical studies do coincide - and therefore active approach is needed in the treatment of these injuries.

Immobilization or early mobilization after an acute soft-tissue injury?

Experimental and clinical studies demonstrate that early, controlled mobilization is superior to immobilization for primary treatment of acute musculoskeletal soft-tissue injuries and postoperative management. Optimal treatment and rehabilitation follow four steps that address response to trauma. First is treating the damaged area with PRICES: protection, rest, ice, compression, elevation, and support. Second, during the first 1 to 3 weeks after the injury, immobilization of the injured tissue areas allows healing without extensive scarring. Third, when soft-tissue regeneration begins, controlled mobilization and stretching of muscle and tendons stimulate healing. Fourth, at 6 to 8 weeks postinjury, the rehabilitative goal is full return to preinjury level of activity.

Motor performance in different dynamic tests in knee rehabilitation

Functional dynamic tests are increasingly used in rehabilitation after injuries of the lower extremities. In these tests quantitative measures (e.g. time, height, distance) are mainly used as parameters, whereas the quality of the neuromuscular performance is poorly evaluated. In the present study the neuromuscular performance of leg muscles in different motor tasks was investigated 10-16 months after ACL-reconstruction. In 39 subjects with arthroscopically assisted ACL-reconstruction and 20 controls, isometric knee extensor strength, thigh circumference, knee stability, subjective knee function and the neuromuscular performance (by kinematic data and EMG) during three dynamic tests (stair descending, one-legged drop jump, one-legged cyclic hops) were measured. During the strength measurements a superimposed twitch technique was used for the detection of neuromuscular inhibition. The results demonstrate a significantly reduced Lysholm-Score and a distinct strength deficit, but no neuromuscular inhibition and no differences in knee stability in the operated leg. Besides reduced motor abilities of the injured leg, significant differences of the neuromuscular performance could be detected. It was evident that different test conditions revealed different persisting changes of the neuromuscular performance, which could not be detected by kinematic parameters alone.

Effects of immobilization and subsequent low- and high-intensity exercise on morphology of rat calf muscles

After a cast immobilization of 3 weeks, the effects of 4-week remobilization by free cage activity or treadmill running on the morphology of the rat soleus and gastrocnemius muscles were studied. The studied morphometric parameters were: percentage volume of intramuscular connective tissue, capillary density, muscle fiber size, number of fibers with a pathological structural alteration, and fiber type distribution. In both muscles, immobilization of 3 weeks produced a significant increase in the connective tissue volume and number of fibers with pathological alterations, with a similar decrease in the capillary number and fiber size. At the same time, the relative amount of type I fibers decreased and type IIA fibers increased. Free remobilization and especially intensified remobilization by treadmill running significantly restored these values towards controls. These findings indicate that in rat soleus and gastrocnemius muscles immobilization-induced accumulation of intramuscular connective tissue, capillary loss, reduction in fiber size, accumulation of fibers with pathological structural alterations, and changes in fiber type distribution are to a great extent reversible phenomena, especially if remobilization is intensified by physical training. In clinical practice, this suggests that in patients with musculoskeletal injuries the postimmobilization rehabilitation should be early and effective.

Free mobilization and low- to high-intensity exercise in immobilization-induced muscle atrophy

After 3 wk of immobilization, the effects of free cage activity and low- and high-intensity treadmill running (8 wk) on the morphology and histochemistry of the soleus and gastrocnemius muscles in male Sprague-Dawley rats were investigated. In both muscles, immobilization produced a significant (P < 0.001) increase in the mean percent area of intramuscular connective tissue (soleus: 18.9% in immobilized left hindlimb vs. 3.6% in nonimmobilized right hindlimb) and in the relative number of muscle fibers with pathological alterations (soleus: 66% in immobilized hindlimb vs. 6% in control), with a simultaneous significant (P < 0.001) decrease in the intramuscular capillary density (soleus: mean capillary density in the immobilized hindlimb only 63% of that in the nonimmobilized hindlimb) and muscle fiber size (soleus type I fibers: mean fiber size in the immobilized hindlimb only 69% of that in the nonimmobilized hindlimb). Many of these changes could not be corrected by free remobilization, whereas low- and high-intensity treadmill running clearly restored the changes toward control levels, the effect being most complete in the high-intensity running group. Collectively, these findings indicate that immobilization-induced pathological structural and histochemical alterations in rat calf muscles are, to a great extent, reversible phenomena if remobilization is intensified by physical training. In this respect, high-intensity exercise seems more beneficial than low-intensity exercise.

Effects of training, immobilization and remobilization on tendons

Since a tendon is a living tissue, it is not a surprise that tendon shows the capacity to adapt its structure and mechanical properties to the functional demands of the entire muscle-tendon unit. However, compared with muscle, the experimental knowledge of the effects of strength or endurance-type training on tendon tissue is scarce and clinical human experiments are completely lacking (1). Research should, however, be able to improve the true understanding of the biomechanical, functional, morphological and biochemical changes that occur in tendons due to training and physical activity, since understanding of the basic physiology of a tissue is the key to understanding its pathological processes (1, 2). Compared with muscle tissue, the metabolic turnover of tendon tissue is many times slower due to poorer vascularity and circulation (1, 3). The adaptive responses of tendons to training are therefore also slower than those in muscles, but they may finally be considerable if the time frame is long enough (3, 4).

Diagnosis and treatment of chronic tendon disorders in sports

Sports and physical activity are becoming more important and more emphasized in the lives of the average person as the health benefits of maintaining an active lifestyle are recognized. In the past most people were primarily active in sports during their time in school. The trend is for more people to continue vigorous activity through middle age and beyond. In addition, as high level athletes continue to reach higher levels of performance more amateur athletes attempt to reach similar levels of intensity, which they may not be able to handle with their level or method of training. This has led to an increase in overuse injuries and chronic tendon injuries. It has been estimated that overuse type injuries account for 30-50% of sports injuries (1).

Effects of immobilization, three forms of remobilization, and subsequent deconditioning on bone mineral content and density in rat femora

Disuse is associated with bone loss, which may not be recoverable. It is not known whether intensified remobilization is beneficial in restoring disuse-related bone loss nor if any such benefit would depend upon continuing mobilization for its maintenance. After an immobilization period of 3 weeks, the effects of free remobilization (11 weeks), and low-and high-intensity treadmill running (11 weeks) with and without subsequent deconditioning (18 weeks) on the bone mineral content (BMC) and density (BMD) of the hindlimb femora of Sprague-Dawley rats (n = 98) were studied using a dual-energy X-ray absorptiometric (DXA) scanner. Our hypothesis was that intensified remobilization is beneficial in restoring the BMC and BMD from disuse to normal while subsequent deconditioning is deleterious to these parameters. Immobilization for 3 weeks produced a significant BMC and BMD loss in the immobilized left femur (range -4.4 to -12.8%; p < 0.05-0.001). In the groups with free remobilization (free cage activity), the body weight-adjusted BMCs and BMDs always remained below those in the controls (range -2.3 to -12.1%; p values ranging from NS to < 0.01). Both low- and high-intensity running restored BMC and BMD in the immobilized limb, the effect being better in the latter group. In both of these groups, the values of the immobilized left limbs and those of the free right limbs exclusively exceeded the corresponding values of the age-matched control rats (left limb values 3.0-21.1% higher with p values ranging from NS to < 0.01; right limb values 7.9-21.4% higher with p < 0.05-0.01). However, after the deconditioning period of 18 weeks, the above described beneficial effects of low- and high-intensity running were lost, the left and right limb BMC and BMD values being lower than those in the age-matched controls (range -3.8 to -8.7%; p values ranging from NS to < 0.05). In conclusion, this study clearly indicates the need for greater than normal activity to restore the BMC and BMD after disuse to normal levels. However, the benefits of intensified remobilization are lost if the activity is terminated, and therefore, after immobilization and disuse, bone loading activities should be continued, perhaps indefinitely.

The causality field (extrinsic and intrinsic factors) in industrial subacute low back pain patients

In a prospective, randomized study, primarily designed to test the efficacy of activation on consecutive blue-collar workers sick-listed for 6 weeks due to subacute low back pain, 25% of the workers were excluded for medical reasons. In the intervention study (n = 103), only a minority of cases (6%) had 'true' subacute complaints, i.e. no prior history of low back pain. Subjective reports on general well-being, health status and work-related ergonomic factors were significantly lower or worse in patients than in reference samples. The randomized intervention study could establish a significant effect of graded activation on work return, but the effect seemed to be restricted to patients moderately disabled, i.e. one-third of the subacute low back pain patients included. A predictive four-factor model on work return increased the possibility of identifing nonresponders (chronic low back pain) more than threefold with a specificity (91%) and sensitivity (74%) comparable to that of clinical disc herniation. The history of a prolonged disablement process, cognitive factors, pain behavior and mentally straining ergonomic factors seemed to be of importance. Psychological reactions, or 'barriers to recovery', were slightly different in treatment and control groups but the type of intervention did not significantly alter the predictive model, suggesting that subsets of the study sample may benefit from other optional functional approaches. Descriptive characteristics of the study sample emphasized that subacute low back pain patients cannot be conceptualized as a homogeneous group. Four sub-groups could be identified: (a) specific medical disorders; (b) spontaneous recovery group; (c) moderately disabled back pain patients; and (d) nonresponders. The results support proposals that treatment should be tailored according to individual needs and that better case management should have priority for those belonging to the nonresponder group.

Exercise and physical health: musculoskeletal health and functional capabilities

An adequately functioning musculoskeletal system is a key factor for functional capacity, independence, and good quality of life. Impaired functional capacity and degenerative diseases of the musculoskeletal organs are one of the most prevalent and increasing sources of morbidity and suffering. Physical activity positively influences most structural components of the musculoskeletal system that are related to functional capabilities and the risk of degenerative diseases. Physical activity also has the potential to postpone or prevent prevalent musculoskeletal disorders, such as mechanical low back pain, neck and shoulder pain, and osteoporosis and related fractures. Exercise can contribute to the rehabilitation of musculoskeletal disorders and recovery from orthopedic surgery. A substantial part of the age-related decline in functional capabilities is not due to aging per se but to decreased and insufficient physical activity. Physical activity has great potential to favorably influence both the normal and pathological structures, functions, and processes. Musculoskeletal benefits of physical activity can be attained by people of all ages and with various diseases. This potential is substantial because many benefits are gained by activity which is moderate in amount and intensity. Scientific evidence is sufficient to recommend regular lifelong physical activity as part of a healthy lifestyle for everyone in order to enhance musculoskeletal health and functions for individual and population levels. However, several important issues regarding the effects, effectiveness, feasibility, and safety of exercise to improve various aspects of musculoskeletal health and functional capabilities need further research.

Vascular density at the myotendinous junction of the rat gastrocnemius muscle after immobilization and remobilization

Muscle injuries often occur at or near the myotendinous junction. Immobilization decreases the tensile strength of the myotendinous junction and predisposes it to strain injury. However, there are no data available on whether physical training or remobilization can lower the susceptibility of the myotendinous junction to strain injuries. We investigated the effects of three different remobilization programs (8 weeks) after immobilization (3 weeks) by evaluating the vascular density at the myotendinous junction of the rat gastrocnemius muscle. The myotendinous junctions had a portal system vascularity, or capillary-arteriole-capillary system, which probably protects the blood supply against pathologic conditions. The vascular density at the myotendinous junction decreased about 30% after immobilization (P < 0.001). After free cage remobilization for 8 weeks, the mean vascular density returned to the level of the controls. After progressively increasing running programs the vascular density was slightly higher in the immobilized myotendinous junction and about 50% higher than controls in the contralateral myotendinous junction (P < 0.001). The capacity of the vascular bed of the rat myotendinous junction to recover from immobilization atrophy seems to be good. Progressively increasing physical training improves the process of revascularization and probably protects an injured and immobilized muscle from reinjury.

Effects of free mobilization and low- to high-intensity treadmill running on the immobilization-induced bone loss in rats

After an immobilization period of 3 weeks, the effects of free remobilization (8 weeks) as well as low- and high-intensity treadmill running on the bone mineral content (BMC) and density (BMD) of the hindlimbs of Sprague-Dawley rats (n = 70) were studied using a dual-energy x-ray absorptiometric scanner. In the low-intensity running program, the rats were allowed to move freely in the cage for 1 week, after which they started to run on a treadmill twice a day for 7 weeks. The speed of the treadmill was 20 cm/s, with an uphill inclination of 10 degrees. The running time was gradually increased from 20 minutes per session to 45 minutes per session. In the high-intensity group, the program was similar, with the exception that the speed of the treadmill was 30 cm/s, with an uphill inclination of 30 degrees. Immobilization for 3 weeks produced a significant BMC and BMD loss in the immobilized left femur and tibia (mean loss 9.6%, p < 0.001) but did not affect the right free limbs. Both low- and high-intensity running restored mineral content in the immobilized limb; however, an average 5% difference (p < 0.05) in mineral content of the right and left limb bones persisted. In the running groups, the values for the immobilized left limbs were at the same level or exceeded (range 3.8-11.6%, p < 0.05-0.01) and those of the free right limbs exclusively exceeded (range 5.3-15.9%, p < 0.05-0.01) the corresponding values of the age-matched control rats.(ABSTRACT TRUNCATED AT 250 WORDS)