Association of lumbar arterial stenosis with low back symptoms: a cross-sectional study using two-dimensional time-of-flight magnetic resonance angiography.

BACKGROUND: Recent studies indicate that diminished blood flow may cause low back symptoms and intervertebral disc degeneration. PURPOSE: To explore the association between lumbar arterial stenosis as detected by two-dimensional time-of-flight magnetic resonance angiography (2D TOF-MRA) and lumbar pain symptoms in an occupational cohort of middle-aged Finnish males. MATERIAL AND METHODS: 228 male subjects aged 36 to 55 years (mean 47 years) were imaged with 2D TOF-MRA. Additionally, 20 randomly selected subjects were scanned with contrast-enhanced MRA (ceMRA). In each subject, the first (L1) to fourth (L4) segmental lumbar arteries were evaluated for lumbar artery stenosis using a dichotomic scale. One subject was excluded because of poor image quality, reducing the study population to 227 subjects. Logistic regression analysis was used to evaluate the association between arterial stenosis in 2D TOF-MRA and low back pain and sciatica symptoms (intensity, duration, frequency). RESULTS: Comparing 2D TOF-MRA and ceMRA images, the kappa value (95% confidence interval) was 0.52 (0.31-0.73). The intraobserver reliability kappa value for 2D TOF-MRA was 0.85 (0.77-0.92), and interobserver kappa was 0.57 (0.49-0.65). The sensitivity of 2D TOF-MRA in detecting stenosis was 0.58, the accuracy 0.89, and the specificity 0.94. In 97 (43%) subjects all arteries were normal, whereas 130 (57%) had at least one stenosed artery. The left L4 artery was most often affected. The degree of arterial stenosis was associated with intensity of low back and sciatic pain, and sciatica pain duration during the past 3 months. CONCLUSION: 2D TOF-MRA is an acceptable imaging method for arterial stenosis compared to ceMRA. Arterial stenosis was associated with subjective pain symptoms, indicating a role of decreased nutrition in spinal disorders.

Injury risk in female floorball: a prospective one-season follow-up.

The purpose of this prospective study was to examine the incidence, nature, causes, and severity of injuries in female floorball. Three hundred and seventy-four licensed female floorball players from Finnish top leagues were observed prospectively for one season (6 months). The practice and game hours of floorball were recorded on an exercise diary. All injuries were registered with a structured questionnaire and verified by a physician. During the study period, 133 out of the 374 (35%) players sustained 172 injuries. The injury incidence was 1.8 per 1000 practice hours and 40.3 per 1000 game hours. Of all injuries, 70% were traumatic and 30% were from overuse. The most common injury type was joint sprain (27%). The most commonly injured sites were the knee (27%) and ankle (22%). Twenty-one of the knee injuries (46%) were serious including 10 anterior cruciate ligament (ACL) ruptures. Eight of ACL ruptures occurred during floorball games, giving an ACL rupture incidence of 3.6 per 1000 game hours. Eleven injuries (6%) needed hospital admission. The study attested that injury rate in floorball game is very high. Injury prevention strategies in female floorball should be targeted at injuries occurring at the knee and ankle.

Knee injuries in leisure-time physical activities: a prospective one-year follow-up of a Finnish population cohort.

This prospective one-year follow-up study compared the risks of knee injuries in various commuting and lifestyle activities as well as in recreational and competitive sports in a 15 to 74-year-old Finnish population cohort. A cohort of 3657 persons was randomly selected from the nationwide population register of Finland. Ninety-two percent of them accepted to participate (n = 3363). The subjects were interviewed by telephone three times during the one-year follow-up. The recorded data included all physical activities that lasted 15 minutes or more, and all injuries that were sustained during these activities. Fifteen percent (n = 321) of all reported injuries affected the knee. The individual risk of knee injury per 1000 exposure hours was low in commuting activities (cycling, walking), 0.06 (95 % CI 0.04 to 0.09) and in lifestyle activities (gardening, hunting, fishing, home repair etc.), 0.04 (0.03 - 0.06). In recreational and competitive sports, the knee injury risk was almost ten times higher, 0.44 (0.39 - 0.50). For commuting activities (p = 0.046) and for recreational and competitive sports (p < 0.001), there was a decreasing injury rate with age. In lifestyle activities (p = 0.038), in turn, there was an increasing trend of injuries with aging. In commuting activities (hazard ratio, HR 5.99, 95 % CI 1.40 to 25.6), the risk of knee injury was significantly higher in women than in men. In conclusion, the knee injury risk per exposure hours is almost ten times lower in commuting and lifestyle activities compared to recreational and competitive sports. The knee injury risk is especially high in the age group of 15 to 25 years, especially in various team sports and ball games. At population level, however, widely practiced low-to-moderate intensity activities with relatively low injury risk per exposure hours produce a large absolute number of knee injuries.

Teenage girls and elderly women living in northern Europe have low winter vitamin D status.

OBJECTIVE: To determine the vitamin D status (serum 25-hydroxyvitamin D; S-25OHD) in adolescent girls and elderly community-dwelling women living in four countries of northern Europe and to explain differences in S-25OHD concentrations between and within the countries. DESIGN: A cross-sectional observational study conducted in a standardised way during February-March. S-25OHD was analysed by high-performance liquid chromatography. Vitamin D and calcium intake was calculated using a standardised food composition database. SETTING: Denmark, Finland, Ireland, and Poland. SUBJECTS: A total of 199 girls (mean (s.d.) age 12.6 (0.5) y) and 221 women (mean (s.d.) age 71.8 (1.4) y). RESULTS: The median (inter quartiles) concentration of S-25OHD was 29.4 (20.3, 38.3) nmol/l for the girls and 40.7 (28.0, 54.2) nmol/l for the women. S-25OHD below 25 nmol/l was found in 37% of the girls and 17% of the women, and S-25OHD below 50 nmol/l was found in 92% of the girls and 37% of the women. Positive significant determinants for S-25OHD in girls were use of vitamin D supplements, and in women sun habits, dietary vitamin D intake, use of vitamin D and calcium supplements. Body mass index and smoking were negative determinants in women. For women predictors could explain the differences between countries (P(country) = 0.09, R(2) = 0.39), but for girls the difference remained significant even after including predictors (P(country) = 0.03, R(2) = 0.15). CONCLUSION: Vitamin D status is low in northern Europe during winter. More than one-third of the adolescent girls have vitamin D status below 25 nmol/l and almost all are below 50 nmol/l. Two-thirds of the elderly community-dwelling women have vitamin D status below 50 nmol/l. Use of vitamin D supplements is a significant positive determinant for S-25OHD for both girls and women (P = 0.001). SPONSORSHIP: The European Fifth Framework Programme (Contract No. QLK1-CT-2000-00623).

A 7-week reduction in salt intake does not contribute to markers of bone metabolism in young healthy subjects.

BACKGROUND: Sodium intake increases urinary calcium excretion and may thus lead to negative calcium balance and bone loss. OBJECTIVE: We hypothesised that reducing sodium intake would reduce urinary calcium excretion and have a beneficial influence in bone metabolism. DESIGN: A total of 29 subjects, 14 males and 15 females, were divided into two study groups. One group (low-sodium group (LS)) reduced sodium intake for 7 weeks by substituting low-salt alternatives for the most important dietary sources of sodium. The other group, serving as a control group (C), was given the same food items in the form of normally salted alternatives. Fasting serum samples as well as 24-h urine samples were obtained in the beginning and at the end of the study. Urinary sodium, urinary calcium, urinary creatinine, serum calcium, serum phosphate, serum creatinine, serum parathyroid hormone (s-PTH), serum C-terminal telopeptides of Type-I collagen and serum bone alkaline phosphatase (s-B-ALP) were analysed. RESULTS: The LS group showed a significant decline (P = 0.001) in urinary sodium/creatinine ratio without a significant effect on urinary calcium/creatinine ratio. In the LS group, s-PTH increased (P = 0.03). The C group showed an increase in s-PTH (P = 0.05) and in s-B-ALP, but no differences were observed between the study groups in the changes of serum markers of calcium and bone metabolism. CONCLUSIONS: We have shown that reducing the sodium intake of young, healthy people with adequate calcium intake over a 7-week period does not affect the markers of bone metabolism.

Active living and injury risk.

The purpose of this study was to get reliable insight into injury risk in various commuting and lifestyle activities, as well as recreational and competitive sports. A cohort of 3 657 persons was randomly selected from the 15- to 74-year-old Finnish population. Ninety-two percent (n = 3 363) of the subjects accepted to participate the one-year follow-up, record all their physical activities that lasted 15 min or more, and register all acute and overuse injuries that occurred during these activities. To collect the information, the study subjects were interviewed by phone by the trained personnel of the Statistics Finland three times in four-month intervals. The individual injury risk per exposure time was relatively low, ranging from 0.19 to 1.5 per 1 000 hours of participation, in commuting and lifestyle activities including walking and cycling to work, gardening, home repair, hunting and fishing, and, in sports such as golf, dancing, swimming, walking, and rowing. The risk was clearly higher in squash, orienteering, and contact and team sports, such as judo, wrestling, karate, rinkball, floorball, basketball, soccer, ice hockey, volleyball, and Finnish baseball ranging from 6.6 to 18.3 per 1 000 hours of participation. However, the highest absolute number of injuries occurred in low-risk activities, such as gardening, walking, home-repair, and cycling, because they are performed so often. In conclusion, individual injury risk per exposure hours is relatively low in commuting and lifestyle activities compared to many recreational and competitive sports. However, at a population level, these low-to-moderate intensity activities are widely practised producing a rather high absolute number of injuries, and thus, preventive efforts are needed in these activities, too.

A controlled trial of the health benefits of regular walking on a golf course.

PURPOSE: To study the effects of regular walking during a golf game on various health and fitness indicators in middle-aged men. METHODS: Study subjects were 55 healthy male golfers aged 48 to 64 years who had been sedentary during the 7 months before the study, and 55 age-matched, similarly sedentary controls. During the 20-week study, those in the intervention group were encouraged to play golf two to three times a week; the controls were not. Measurements of body composition, cardiorespiratory performance, motor and musculoskeletal fitness, blood pressure, and serum lipid, glucose, and insulin levels were obtained at baseline and after the 20-week study. RESULTS: Walking during a golf game was a practical and safe form of physical activity with high adherence. It significantly increased aerobic performance and trunk muscle endurance, with a net difference (pretraining to posttraining change between the golfers and controls) of 36 seconds (95% confidence interval [CI]: 19 to 53 seconds, P < 0.001) for treadmill walking time and 13 seconds (95% CI: 2 to 24 seconds, P = 0.02) for static back extension. In addition, regular walking favorably affected body composition, including reductions in weight of 1.4 kg (95% CI: 0.6 to 2.1 kg, P < 0.001), in waist circumference of 2.2 cm (95% CI: 1.0 to 3.3 cm, P < 0.001), and in abdominal skin fold thickness of 2.2 cm (95% CI: 0.9 to 3.4 cm, P = 0.001). Golfers also had significantly greater increases in serum high-density lipoprotein (HDL) cholesterol levels and in the ratio of HDL cholesterol to total cholesterol. CONCLUSIONS: Regular walking had many positive effects on the health and fitness of sedentary middle-aged men. Walking during a golf game is characterized by high adherence and low risk of injury and is therefore a good form of health-enhancing physical activity.

Factors affecting the relation between heart rate and energy expenditure during exercise.

This study evaluated the ability to use the relationship between heart rate (HR) and oxygen uptake (VO2) to estimate energy expenditure during physical activity (AEE). General prediction equations were established based on the individual relations between HR and AEE. Forty-two women, (mean age 38.1 [SD 9.8] years, BMI 23.9 [SD 4.4]), and 45 men (40.3 [SD 9.2] years, BMI 24.7 [SD 2.9]), carried out two incremental tests, one with a cycle ergometer and another on a treadmill. Subjects also performed a 10 minute steady-state exercise, cycling and walking. Respiratory gases were obtained from indirect calorimetry. AEE was calculated from VO2 and carbon dioxide production (VCO2). The predicted AEE was compared with the AEE measured during the steady-state exercise. Using the generalised linear model, two alternative models were found to predict AEE and HR. The first showed a three-way interaction between HR, body weight and gender (p = 0.022) and also between HR age and gender (p=0.083). The second produced a three-way interaction between HR, body weight and gender (p=0.057). For cycling and walking, respectively, the predicted AEE overestimated the actual AEE by 17.7 (SD 23.2)% and 6.2 (SD 19.3)% in the first model and by 17.9 (SD 22.7)% and 6.6 (SD 19.8)% in the second during the steady-state exercise. It was concluded that at least gender and body weight should be included when HR is used to predict AEE.

Alpine ski bindings and injuries. Current findings.

In spite of the fact that the overall incidence of alpine ski injuries has decreased during the last 25 years, the incidence of serious knee sprains usually involving the anterior cruciate ligament (ACL) has risen dramatically since the late 1970s. This trend runs counter to a dramatic reduction in lower leg injuries that began in the early 1970s and to date has lowered the risk of injury below the knee by almost 90%. One of the primary design objectives of modern ski boots and bindings has been to protect the skier from tibia and ankle fractures. So, in that sense, they have done an excellent job. However, despite advances in equipment design, modern ski bindings have not protected the knee from serious ligament trauma. At the present time, we are unaware of any binding design, settings or function that can protect both the knee and lower extremities from serious ligament sprains. No innovative change in binding design appears to be on the horizon that has the potential to reduce the risk of these severe knee injuries. Indeed, only 1 study has demonstrated a means to help reduce this risk of serious knee sprains, and this study involved education of skiers, not ski equipment. Despite the inability of bindings to reduce the risk of severe knee injuries there can be no doubt that improvement in ski bindings has been the most important factor in the marked reduction in incidence of lower leg and ankle injuries during the last 25 years. The authors strongly endorse the application of present International Standards Organisation (ISO) and American Society for Testing and Materials (ASTM) standards concerning mounting, setting and maintaining modern 'state of the art' bindings.

Majority of hip fractures occur as a result of a fall and impact on the greater trochanter of the femur: a prospective controlled hip fracture study with 206 consecutive patients.

The objectives of this study were to learn how hip fracture patients fall, and to compare the mechanics of their falls with those falls that did not result in hip fracture. In this way we sought to obtain reliable insight into the etiology and pathogenesis of hip fracture and fracture prevention. A total of 206 consecutive patients with fresh hip fracture and 100 controls were interviewed and examined between October 1994 and May 1996. The only inclusion criterion was that the fracture had occurred within 24 hours of hospital admittance. The control subjects were admitted from the same community after an accidental fall that did not result in hip fracture. The characteristics of the accident were determined by personal interview and examination of the patients within 24 hours of the event. In 98% of the hip fracture patients, the fracture was a result of a fall. The majority of the patients (76%) reported that they had fallen directly to the side. Forty-eight fracture cases had one or more eyewitnesses and their reports supported this observation. In 56% of the hip fracture patients, a fresh subcutaneous hematoma was seen on the greater trochanter of the proximal femur; such a hematoma was rare in the controls (6%) (P < 0. 001), and this gave evidence for the direct impact of the greater trochanter during the fall of the hip fracture subjects. Most of the elderly fallers who fractured a hip did not manage to break the fall, e.g., with an outstretched arm. In conclusion, our results suggest that a typical hip fracture is the result of a fall and a subsequent impact on the greater trochanter of the proximal femur. The clinical implication of this finding is that effective prevention of hip fractures could be achieved by the diminution of the number and severity of falls of the elderly. We suggest that the severity of the falls (impacts on the greater trochanter) could be decreased by an external hip protector.

Isokinetic muscle performance after surgery of the lateral ligaments of the ankle.

In this study, we assessed the isokinetic strength and power profile of 138 patients with a surgically treated lateral ligament injury of an ankle. In addition, the outcome predicting factors were analyzed. The measurements were done 6.2+/-0.8 years after the surgery using the Cybex II isokinetic dynamometer. The general strength status of the patients was good, the isokinetic testing showing no or only moderate (always < or = 18%) average strength deficits in the peak torque values of dorsiflexor and plantar flexor muscles of the injured ankle. Of the outcome predicting variables, only the age of the patient in the group with surgery for chronic ankle instability correlated significantly with the isokinetic peak torque deficits: the older the subject, the greater the peak torque deficit in the injured ankle (r(s) = -0.388 with p = 0.015) in ankle dorsiflexion at the speed of 60 degrees/s. In conclusion, patients having surgery for ankle ligament insufficiency, either in acute or chronic phase of the injury, seem to recover well showing no remarkable deficiencies in the isokinetic ankle muscle strengths several years after the repair.

An outcome study of chronic patellofemoral pain syndrome. Seven-year follow-up of patients in a randomized, controlled trial.

BACKGROUND: We determined prospectively the long-term outcomes of nonoperative treatment of chronic patellofemoral pain syndrome. METHODS: Of forty-nine patients in a prospective, randomized, double-blind study of unilateral chronic patellofemoral pain syndrome in the knee, forty-five were reexamined seven years after the initial trial of treatment. In the earlier trial, the short-term (six-month) effects of intra-articular injections of glycosaminoglycan polysulfate combined with intensive quadriceps-muscle exercises were compared with those of injections of a placebo combined with exercises and with those of exercises alone. At seven years, the follow-up consisted of standardized subjective, functional, and clinical assessments and muscle-strength measurements as well as magnetic resonance imaging, radiography, and bone-densitometry measurements of the knee. RESULTS: At six months, complete subjective, functional, and clinical recovery had occurred in almost three-fourths of the patients and, with the numbers available for study, neither significant nor clinically important differences among the three initial treatment groups were detected. The subjective and functional parameters showed few changes between six months and seven years; almost three-fourths of the patients still had full subjective and functional recovery at the time of the latest follow-up. However, according to the physician's clinical evaluation, the number of patients who had no symptoms on the patellar compression and apprehension tests decreased over time, from forty-two (93 percent) and forty (89 percent) of forty-five patients at six months to thirty (67 percent) and thirty-one (69 percent) at seven years; these changes were significant (p = 0.002 and p = 0.023, respectively). The number of patients who had crepitation on the patellar compression test increased over time, from twenty-six (58 percent) at six months to thirty-six (80 percent) at seven years (p = 0.021). The physician's overall assessment showed a similar trend, with thirty-four patients (76 percent) having had complete recovery at six months compared with thirty (67 percent) at seven years; however, with the numbers available, this change was not significant (p = 0.420). Magnetic resonance imaging, performed for thirty-seven patients, revealed no abnormalities in twenty-four (65 percent), mild abnormalities in four (11 percent), moderate abnormalities (a 25 to 75 percent decrease in the thickness of the cartilage) in seven (19 percent), and overt patellofemoral osteoarthritis in two (5 percent) at seven years. CONCLUSIONS: The seven-year overall outcome was good in approximately two-thirds of the patients. However, the remaining patients still had symptoms or objective signs of a patellofemoral abnormality.

Effect of anterior cruciate ligament injury of the knee on bone mineral density of the spine and affected lower extremity: a prospective one-year follow-Up study.

The objective of this 1-year prospective follow-up study was to assess, with dual-energy X-ray absorptiometry (DXA), the effect of an anterior cruciate ligament (ACL) injury of the knee on areal bone mineral density (BMD) of the injured extremity and lumbar spine in two separate patient groups: 21 surgically treated patients (group A) and 12 conservatively treated patients (group B). Clinical and functional status of the patients and BMD of the spine (L2-L4), dominant distal radius, femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and calcaneus of both lower extremities were determined at the time of the injury and after 4, 8, and 12 months. A surgically treated, complete ACL rupture (group A) resulted in considerable and statistically significant bone loss to the affected knee (distal femur 21%, patella 17%, proximal tibia 14%; P < 0.001 in each), whereas the other sites were clearly less affected. Patients with a conservatively treated, complete or partial ACL injury (group B) had only a small but statistically significant bone loss at the patella (-3%; P = 0.005) and proximal tibia (-2%; P = 0.022) of the injured knee, and the other sites remained unchanged. The obvious differences between the groups A and B in the severity of the injury itself (complete or partial tear), its treatment (surgical or conservative), and subsequent rehabilitation (longer nonweight-bearing times in group A) explain these different BMD results, and the forthcoming years will show whether the considerable posttraumatic osteoporosis in the affected knee of group A patients will finally recover, and if so, to what extent.

Increasing number and incidence of fall-induced severe head injuries in older adults: nationwide statistics in Finland in 1970-1995 and prediction for the future.

To increase knowledge about recent trends in the number and incidence of various fall-induced injuries among older adults, the authors selected from the National Hospital Discharge Register all patients 60 years of age or older who were admitted to hospitals in Finland for primary treatment of a first fall-induced severe head injury during 1970-1995. Similar patients aged 30-39 years served as a reference group. For the study period, the number and incidence (per 100,000 persons) of fall-induced severe head injuries in Finnish persons 60 years of age or older increased considerably (554 and 85, respectively, in 1970 compared with 1,393 and 144, respectively, in 1995). The age-adjusted incidence of these injuries also increased in women, from 80 in 1970 to 125 in 1995, and in men, from 102 in 1970 to 147 in 1995. In the reference group (patients aged 30-39 years), the absolute numbers and incidences of similar injuries did not show consistent trend changes over time. We conclude that the number of fall-induced severe head injuries in elderly Finnish women and men is increasing at a rate that cannot be explained simply by demographic changes, and therefore vigorous preventive measures should be instituted at once to control the increasing burden of these devastating injuries.

Which factors predict the long-term outcome in chronic patellofemoral pain syndrome? A 7-yr prospective follow-up study.

PURPOSE: The aim of this prospective study was to determine which factors predict the long-term (7-yr) outcome of conservative treatment of chronic patellofemoral pain syndrome. METHODS: The general predictors registered were age, gender, body composition, athletic activity, duration of symptoms, and follow-up time. The remaining 13 predictors were clinical or radiological measurements of the knee joint. In 45 consecutive patients, these predictors were measured at the beginning of the 6-wk treatment protocol (rest, NSAID, and intense isometric quadriceps exercises) and at the end of the follow-up. The outcome criteria were the 100-mm Visual Analog Scale (VAS) pain score, and the Lysholm and Tegner functional knee scores. RESULTS: The extension strength of the affected knee was a significant predictor of the outcome scores (Lysholm score: r = 0.37, P < 0.05, and the Tegner score: r = 0.39, P < 0.01): the smaller the strength difference between the affected and unaffected knee, the better the outcome. In a multiple stepwise regression analysis, the variables pain in the patella apprehension test, patella crepitation at baseline and at follow-up, bilateral symptoms developed during the follow-up, and patient's age and height were also independent predictors of the final outcome and could together account 60% for the variation seen in the Lysholm score and 52% in the Tegner score, respectively. Neither the radiologic nor the magnetic resonance imaging changes at the affected knee had a clear association with the 7-yr outcome. CONCLUSIONS: The results of the current and our previous (15) observations support the concept that restoration of good quadriceps strength and function to the affected extremity is important for good recovery of the patient. In addition, negative findings in the clinical tests of patellar pain and crepitation, nonappearance of bilateral symptoms during the follow-up, low body height, and young age are associated with good long-term outcome.

Bone mineral density in the chronic patellofemoral pain syndrome.

Bone mineral density (BMD) and clinical status of 40 patients with a chronic, unilateral patellofemoral pain syndrome (PFPS) were determinated. The mean duration of the disease at the time of the follow-up was 7.6 +/- 1.8 (SD) years. The BMD was measured at the spine (L2-L4), and the femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and calcaneus of both lower extremities using a dual-energy X-ray absorptiometric (DXA) scanner. The mean BMD of the affected limb (compared with the unaffected side) was significantly lower in the distal femur (-3.3%; P = 0.002), patella (-2.5%; P = 0.016), and proximal tibia (-1.9%; P = 0.008). The femoral neck, trochanter area of the femur, and calcaneus showed no significant side-to-side differences, and the spinal BMDs of men and women with the PFPS were comparable with the manufacturer's age-adjusted reference values for Western European men and women. The relative BMDs of the affected knee showed strongest correlation with the muscle strength of the same knee: the better the muscle strength compared with the healthy knee, the higher the relative BMD (r = 0.56-0.58 with P < 0.001 in each anatomic site of the knee). In the stepwise regression analysis, low body weight or low body mass index, high level of physical activity, the patient's good subjective overall assessment of his/her affected knee, and short duration of the symptoms were also independent predictors of the high relative BMD in the affected knee so that along with the muscle strength these variables could account for 51% of the variation seen in the relative BMD of the femur, 61% in the patella, and 54% in the proximal tibia. In conclusion, chronic patellofemoral pain syndrome results in a significantly decreased BMD in the knee region of the affected limb. The spine, proximal femur, and calcaneus are not affected. Recovery of normal muscle strength and knee function seems to be of great importance for good BMD.

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.

Location and distribution of non-collagenous matrix proteins in musculoskeletal tissues of rat.

The study assessed immunohistochemically the location and distribution of various non-collagenous matrix proteins (fibronectin, laminin, tenascin-C, osteocalcin, thrombospondin-1, vitronectin and undulin) in musculoskeletal tissues of rat. Fibronectin and thrombospondin-1 were found to be ubiquitous in the studied tissues. High immunoreactivity of these proteins was found in the extracellular matrix of the anatomical sites where firm bindings are needed, i.e. between muscle fibres and fibre bundles, between the collagen fibres of a tendon and at myotendinous junctions, osteotendinous junctions and articular cartilage. Tenascin-C was found in the extracellular matrix of regions where especially high forces are transmitted from one tissue component to the other, such as myotendinous junctions and osteotendinous junctions. Laminin was demonstrated in the basement membranes of the muscle cells and capillaries of the muscle-tendon units. Osteocalcin immunoreactivity concentrated in the extracellular matrix of areas of newly formed bone tissue, i.e. in the subperiosteal and subchondral regions, osteoid tissue and mineralized fibrocartilage zone of the osteotendinous junction. Mild vitronectin activity could be seen in the extracellular matrix of the osteotendinous and myotendinous junctions, and high activity around the bone marrow cells. Undulin could be demonstrated in the extracellular matrix (i.e. on the collagen fibres) of the tendon and epimysium only. However, it was co-distributed with fibronectin and tenascin-C. Together, these findings on the normal location and distribution of these non-collagenous proteins in the musculoskeletal tissues help to form the basis of knowledge against which the location and distribution of the these proteins in various pathological processes could be compared.

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).