Risk factors for recurrent stress fractures in athletes.

Our aim was to identify factors predisposing athletes to multiple stress fractures, with the emphasis on biomechanical factors. Our hypothesis was that certain anatomic factors of the ankle are associated with risk of multiple stress fractures of the lower extremities in athletes. Thirty-one athletes (19 men and 12 women) with at least three separate stress fractures each, and a control group of 15 athletes without fractures completed a questionnaire focusing on putative risk factors for stress fractures, such as nutrition, training history, and hormonal history in women. Bone mineral density was measured by dual-energy x-ray absorptiometry in the lumbar spine and proximal femur. Biomechanical features such as foot structure, pronation and supination of the ankle, dorsiflexion of the ankle, forefoot varus and valgus, leg-length inequality, range of hip rotation, simple and choice reaction times, and balance in standing were measured. There was an average of 3.7 (range, 3 to 6) fractures in each athlete, totaling 114 fractures. The fracture site was the tibia or fibula in 70% of the fractures in men and the foot and ankle in 50% of the fractures in women. Most of the patients were runners (61%); the mean weekly running mileage was 117 km. Biomechanical factors associated with multiple stress fractures were high longitudinal arch of the foot, leg-length inequality, and excessive forefoot varus. Nearly half of the female patients (40%) reported menstrual irregularities. Runners with high weekly training mileage were found to be at risk of recurrent stress fractures of the lower extremities.

EPO, red cells, and serum transferrin receptor in continuous and intermittent hypoxia.

PURPOSE: Erythropoietic response in 10 healthy nonsmoking volunteers exposed to normobaric hypoxia continuously or intermittently 12 h daily for 7 d was evaluated in a randomized cross-over study. METHODS: An oxygen content of 15.4% corresponding to an altitude of 2500 m was created by adding nitrogen into room air in a flat. Venous blood samples for hemoglobin (Hb), hematocrit (Hct), reticulocytes, serum erythropoietin (S-EPO), red cell 2,3-diphosphoglycerate (2,3-DPG), serum ferritin (S-Ferrit), and serum soluble transferrin receptor (S-TransfR) were drawn at 8:00 a.m. RESULTS: S-EPO was increased from baseline values of 22.9+/-9.6 and 20.5+/-10.1 U x L(-1) to 40.7+/-12.9 (P < 0.05) and 35+/-14.3 U x L(-1) (P < 0.05) after the first night in continuous and intermittent hypoxia, respectively, and remained elevated throughout both exposures. Hb and Hct values did not show any significant changes. Red cell 2,3-DPG rose from baseline a value of 5.0+/-0.8 to 5.9+/-0.7 mmol x L(-1) (P < 0.05) after the first day in continuous hypoxia and from 5.2+/-0.7 mmol x L(-1) to 6.1+/-0.5 mmol x L(-1) on day 3 (P < 0.05) during intermittent hypoxia. The reticulocyte count rose significantly (P < 0.05) after 5 d in both experiments. S-transferrin receptor level rose significantly from 2.2+/-0.4 and 2.1+/-0.5 mg x L(-1) to 2.6+/-0.5 mg x L(-1) and 2.3+/-0.6 mg x L(-1) on day 5 (P < 0.05), to 2.7+/-0.5 mg x L(-1) and 2.5+/-0.6 mg x L(-1) on day 7 (P < 0.05) under continuous and intermittent hypoxia, respectively. CONCLUSIONS: We suggest that intermittent exposure to moderate normobaric hypoxia 12 h daily for 1 wk induces a similar stimulation of erythropoiesis as continuous exposure.

Results of surgical treatment of unresolved Osgood-Schlatter lesion.

BACKGROUND AND AIMS: We present our experience with surgical treatment of unresolved, painful, late Osgood-Schlatter disease. MATERIAL AND METHODS: In 70 operations performed in 67 patients (in three bilaterally) an ossicle under the distal patellar tendon was removed in 62 cases. In eight cases, excision of the prominent tibial tubercle and/or drilling of the epiphysis was performed. Additional procedures, such as rasping of the uneven anterior tibial surface, excision of inflammed bursa or the devitalized portion of the tendon, were done 21 times. Most patients were athletes or physically active young people. The mean age was 19.6 years. 54 operations were done on males and 16 on females. They had been followed preoperatively for 18 months and after surgery 2.2 years. RESULTS: The final results were excellent or good in 56, moderate in 9, poor in 3 and unknown in 2 cases. CONCLUSIONS: Osgood-Schlatter's disease may leave an ossicle under the distal patellar tendon, a prominent tibial tubercle or an uneven surface of anterior superior tibia. These may lead to pain and disability due to recurrent injuries or athletic exercises. Surgical treatment gives good results in chronic unresolved cases.

mRNA levels for alpha-subunit of prolyl 4-hydroxylase and fibrillar collagens in immobilized rat skeletal muscle.

There is evidence that immobilization causes a decrease in total collagen synthesis in skeletal muscle within a few days. In this study, early immobilization effects on the expression of prolyl 4-hydroxylase (PH) and the main fibrillar collagens at mRNA and protein levels were investigated in rat skeletal muscle. The right hindlimb was immobilized in full plantar flexion for 1, 3, and 7 days. Steady-state mRNAs for alpha- and beta-subunits of PH and type I and III procollagen, PH activity, and collagen content were measured in gastrocnemius and plantaris muscles. Type I and III procollagen mRNAs were also measured in soleus and tibialis anterior muscles. The mRNA level for the PH alpha-subunit decreased by 49 and 55% (P < 0.01) in gastrocnemius muscle and by 41 and 39% (P < 0.05) in plantaris muscle after immobilization for 1 and 3 days, respectively. PH activity was decreased (P < 0.05-0.01) in both muscles at days 3 and 7. The mRNA levels for type I and III procollagen were decreased by 26-56% (P < 0.05-0.001) in soleus, tibialis anterior, and plantaris muscles at day 3. The present results thus suggest that pretranslational downregulation plays a key role in fibrillar collagen synthesis in the early phase of immobilization-induced muscle atrophy.

Ruptures of the Achilles tendon: relationship to inequality in length of legs and to patterns in the foot and ankle.

We studied 101 patients who were operated on at Oulu University Hospital for ruptured Achilles tendon from 1987 to 1992 (inclusive), and 87 healthy control patients from among Army conscripts. The mean inequality in length of legs (ILL) was 5 +/- 4 mm. Among the 48 patients with ILL > or = 5 mm, the side affected with ruptured tendon was longer in 48% of cases and shorter in 52%. An underpronating alignment of the ankle and foot (based on beta45 measurement of the angle < or = 4 degrees) was found in 21% of patients and 5% of controls (P < 0.001). A combination of high longitudinal arch and underpronating alignment of the ankle was seen in 10% of patients and 1% of controls (P < 0.001). About 37% of the patients' feet and 29% of feet in controls were classified as having a high arch (P = 0.001). ILL or hyperpronation of the ankle seem to not be predisposing factors for ruptures of the Achilles tendon. High longitudinal arches were somewhat overrepresented, being associated with less pronation of the ankle and less varus in the forefoot than was seen in controls.

Submaximal exercise in the cold: does cooling potentiate the development of muscle injuries in the rat?

To test the effect of low ambient temperature on muscular strain and possible development of muscle injuries, male Sprague-Dawley rats (n = 35) were exercised at a speed of 15 m min-1 on a treadmill at a 6 degrees inclination for 1.5 h in a warm (22 degrees C) or a cold (-10 degrees C) environment. Blood and tissue samples were collected 0 and 48 h postexercise. Blood glucose, lactate, pyruvate, cortisol, epinephrine (E) and norepinephrine (NE) were determined to investigate the effect on energy metabolism. To estimate the degree of physical strain, possible muscle injury and regenerative processes of muscles in response to exercise in the cold, serum creatine kinase (CK), lactate dehydrogenase (LDH), muscle beta-glucuronidase and prolyl-4-hydroxylase (PH) activities were measured. In addition, histology of the hindlimb muscles m. soleus and m. tibialis anterior was examined. In general, the circulating level of metabolic substrates during exercise were unaffected by the exercise and independent of ambient temperature. Plasma cortisol increased significantly during exercise (P < 0.01), but was unaffected by the thermal strain. Of the myocellular enzymes, serum CK increased by 100% (P < 0.01) and LDH by 93% (P < 0.05) during exercise in the cold compared with exercise in warm, indicating a higher physical strain. However, exercise in the cold did not result in muscle injuries as judged by the unaltered muscular beta-glucuronidase, PH levels and muscle morphology. It is concluded that the exercise type and intensity used caused stress that was independent of the ambient temperature. In addition, the rats were able to maintain unaltered circulating levels of energy substrates also in the cold. Finally, exercise in the cold increased muscular strain but did not result in muscle injuries.

Ischial tuberosity apophysitis and avulsion among athletes.

Ischial tuberosity pain in athletes may be caused by several clinical entities, which include acute and old bony or periosteal avulsions and apophysitis. We studied the natural course of these injuries based on our clinical case series of fourteen patients with apophysitis and twenty-one with avulsion of the ischial tuberosity. Only patients with the diagnosis confirmed by X-ray finding were included. The clinical diagnostic criteria by ischial apophysitis consisted of gradually increasing functional and palpatory pain at the ischial tuberosity without any major trauma at the beginning of the symptoms. Typically there was asymmetry on plain radiographs of the ischial tuberosities in apophysitis; the involved apophyseal area became sclerotic, wider than the non-symptomatic apophysis, osteoporotic patches developed and the lower margin of the ischial tuberosity became irregular. The patients with avulsion reported an acute trauma at the beginning of the symptoms and an avulsion fragment was immediately after injury or later seen in plain radiographs. The mean age of the patients with apophysitis (14.1 yrs) was lower than that of the subjects with avulsions (18.9 yrs). Apophysitis of the ischial tuberosity usually healed well without complications. Avulsions often caused more prolonged pain with referral pain to the posterior parts of the thigh which often required operative interventions. A small bony or periosteal avulsion sometimes grew to a pseudotumor calcification. We recommend conservative treatment as the primary treatment modality for both ischial tuberosity apophysitis and avulsion fractures.

High intensity knee extensor training, in patients with chronic heart failure. Major skeletal muscle improvement.

Skeletal muscle adaptations to high intensity knee extensor strength and/or endurance training in patients with chronic heart failure were investigated. Eleven patients with chronic heart failure were randomized into two groups and exercised the m. quadriceps femoris 3 days/week for 8 weeks. After training, the maximal exercise intensity tolerated on the ergometer cycle was raised from 99 (32) to 114 (40) watts (W, P < 0.05) for all 11 patients. Peak dynamic knee extensor work rate showed the greatest increase after endurance training (40%, P < 0.01). Maximal dynamic and isometric strength were elevated by 40-45% (P < 0.05) after strength training. The cross-sectional area of m. quadriceps femoris was increased in the strength-trained legs (9%, P < 0.05), and the capillary per fibre ratio of m. vastus lateralis was raised by 47 and 58% in the endurance-trained legs (P < 0.05). The oxidative enzyme activity in m. vastus lateralis was significantly raised above 50% after endurance training, whereas glycolytic enzyme activity was unaltered. The peripheral skeletal musculature in patients with chronic heart failure adapts fairly quickly to high intensity knee extensor training. This results in a marked rise in local, and a small rise in total work capacity, indicating maintained plasticity of skeletal muscle in chronic heart failure patients.

Skeletal muscle collagen type I and III mRNA, [corrected] prolyl 4-hydroxylase, and collagen in hypobaric trained rats.

Skeletal muscle collagen expression was studied in normobaric sedentary (NS) and training (NT) and hypobaric sedentary (HS) and training (HT) rats after experimental periods of 10, 21, and 56 days. The weights of fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles were increased between the experimental period of 21 and 56 days so that EDL weight was 57 (P < 0.01) and 36% (P < 0.05) higher in 56 days HS (56HS) and 56 days HT (56HT), respectively, than in 56 days NS (56NS). Soleus muscle weight was higher in 56HS (61%; P < 0.01) and in 56HT (27%; P < 0.05) than in 56NT. In EDL muscle, collagen type I mRNA level was lower in 56HT than in 56NS (36%; P < 0.05) and 56NT (44%; P < 0.01). In 56HT, collagen type III mRNA level was 39 (P < 0.01) and 42% (P < 0.05) lower than in 56NS and 56HS, respectively. In soleus muscle, prolyl 4-hydroxylase activity was greater (P < 0.05) in 56NT, 56HS, and 56HT than in 56NS. Total hydroxyproline content in EDL muscle was increased in 56HS and 56HT and in soleus muscle of 56HS. In conclusion, although collagen types I and III mRNA levels in EDL muscle decreased in 56HT, the prolyl 4-hydroxylase data suggest unchanged synthesis of total collagen. Exposure to hypobaric conditions as such, its combination to endurance training, as well as training in normobaric conditions increased prolyl 4-hydroxylation capacity in soleus muscle, which may indicate respective change in collagen synthesis rate.

The effects of moderate altitude on circulating thyroid hormones and thyrotropin in training athletes.

OBJECTIVE: To study the effect of moderate altitude on thyroid hormones among training athletes. EXPERIMENTAL DESIGN: Serum total and free triiodothyronine (T3), thyroxine (T4), and thyrotropin (TSH) concentrations were measured among eight training athletes at sea level and subsequently during training for 12 days at the altitude of 1100-2700 m. SETTING: Deaconess Institute of Oulu, and Division of Sports Medicine, Department of Physiology, University of Oulu, Finland. PARTICIPANTS: National top class skiers who normally live at sea level. RESULTS: Serum concentrations of TSH, total and free T4, and reverse T3 did not change significantly. A significant decrease in serum total T3 levels from 1.9 nmol*1-1 on days 1-3 to 1.6-1.7 nmol*l-1 on days and 5-6 (p < 0.05) was observed. Serum albumin decreased (p < 0.05) on days 1-8 at altitude and correlated to serum total T3 (R = 0.36, p = 0.013). Serum free T3 increased steadily at moderate altitude and reached a significantly higher level (p < 0.05) at the end of the training period than before. CONCLUSIONS: The serum free T3 increases when unacclimatized sea level skiers move to train at moderate altitude.

Diagnosis and treatment of stress fracture of the patella in athletes.

Five cases of stress fracture of the patella in athletes are presented. Four of these occurred transversally in the lower part and one longitudinally in the lateral part of the patella. Three of the patients were females (endurance runner, high jumper, and orienteerer) and two males (volleyball and soccer player). The diagnosis was made 2-8 months from the onset of the symptoms. Conservative treatment was successful in only one patient; all others were treated surgically, with good end result. Drilling of the fracture line was performed twice with metal wire cerclage fixation, excision of the lateral fragment was carried out once, and a bone graft with K wires and cerclage compression (tension band) was performed once. In all cases the patellar retinaculum was intact, indicating a stress injury. Stress fracture of the patella is a rare overuse injury, and therefore difficulties and delays in the diagnosis and treatment may occur. In cases with delayed diagnosis we recommend operative treatment.

Effects of streptozotocin-induced diabetes, physical training and their combination on collagen biosynthesis in rat skeletal muscle.

The effects of streptozotocin-induced diabetes, physical training and their combination on the activities of prolyl 4-hydroxylase (PH) and galactosylhydroxylysyl glucosyl-transferase (GGT), both marker enzymes of collagen biosynthesis, and on the concentration of hydroxyproline (Hyp) were studied in vastus lateralis, rectus femoris and gastrocnemius muscles in rats. The experimental period was 12-16 weeks. Diabetes had an overall decreasing effect on specific PH activity in all muscles studied, whereas specific GGT activity remained at control level. Total PH and GGT activities decreased in all three muscles in the diabetic animals (P < 0.001). Training caused an increase in PH and GGT activities in gastrocnemius in non-diabetic rats, whereas training in combination with diabetes did not change specific PH or GGT activity. Diabetes increased specific Hyp concentration in vastus lateralis and gastrocnemius in trained diabetic rats (P < 0.05), whereas training decreased Hyp level significantly (P < 0.05) in vastus lateralis in non-diabetic rats, but not in diabetic animals. The results suggest that in streptozotocin-induced diabetes the decrease in collagen synthesis rate exceeds the negative total protein balance in the muscle. Although physical training may have an increasing effect on muscular collagen synthesis in non-diabetic rats, it is unable to prevent the decreasing effect of diabetes on collagen synthesis.

Stress fracture of the medial malleolus.

We studied eight patients who had a stress fracture of the medial malleolus. The main symptom was localized pain on the medial side of the ankle. The initial radiographs revealed the lesion for only three patients; for the other patients, the diagnosis was made with the use of isotope scans and was confirmed with computerized tomography scans, magnetic resonance images, or subsequent plain radiographs. One vertical fracture was treated initially with compression with AO screws. On the basis of our experience with stress fractures in other bones, drilling was performed to enhance the formation of bone in two patients who had delayed healing and who had had symptoms for eight and twelve months. The fractures healed four and five months after the drilling. The five patients who were managed non-operatively had to avoid running and jumping for at least three months (average, four months) so that healing could take place. All five of these fractures healed within five months.

Metabolic response and muscle glycogen depletion pattern during prolonged electrically induced dynamic exercise in man.

Muscle glycogen depletion pattern and metabolic responses during voluntary (VOL) and functional electrical stimulated (FES) dynamic knee-extensor exercise with one leg were evaluated. Seven healthy men exercised for 60 minutes at 30 W with an pulmonary oxygen uptake of 0.8 and 1.01 min-1, and respiratory exchange ratios of 0.90 and 0.95 in VOL and FES, respectively. Heart rate reached a level around 90 beats min-1 (VOL) and up to 110 beats min-1 (FES). Muscle glycogen decreased in FES with 260 and 290 mmol kg-1 d.w. in vastus lateralis and m. rectus femoris, respectively, compared with 45 and 160 mmol kg-1 d.w. in VOL (p < 0.05). In FES the percentage of empty and almost empty fibres determined by periodic acid-Schiff staining in vastus lateralis and rectus femoris was 50 and 77% of type I, 63 and 90% of type IIa, and 59 and 84% of type IIb fibres, respectively, whereas in VOL it was 24 and 26% of type I, 7 and 19% of type IIa, and 2 and 3% of type IIb fibres. Muscle lactate reached 30 mmol kg-1 d.w. in FES and was 9 mmol kg-1 d.w. lower in VOL. The changes in blood lactate and NH3 during the exercise were slightly higher in FES than in VOL, whereas the alterations in glucose, FFA, and K+ were small in both exercise modes. The pressure in the two muscle portions at different locations (proximal-distal) and depths was always higher (approximately 50%) in FES than in VOL, reaching levels around 55 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)

Training effects of electrically induced dynamic contractions in human quadriceps muscle.

The effects of electrically induced dynamic muscle contractions on muscle endurance, strength, morphology and enzymatic adaptation were studied in seven male physical education students. The training program consisted of electrically induced one-leg extensions on a modified Krogh cycle with a 30-Watt (W) load for 60 min, 3 times a week for 4 weeks. Muscle fiber type composition was unchanged, but diffusional capacity was increased after electromyostimulation training. The endurance capacity in the trained leg increased by 82% (p < 0.01), but there were no significant changes in citrate synthase, phosphofructokinase activities, and carbonic anhydrase III and myoglobin contents, suggesting that neural adaptation and learning were more important factors for the increased endurance capacity than enzymatic adaptation. Prolyl 4-hydroxylase activity, a marker of collagen biosynthesis, increased 3-fold (p < 0.01) as a result of the training. This could be due to muscle damage caused by electrically induced muscle contractions. In conclusion, electrically induced dynamic muscle contractions can increase muscle endurance without clear concominant changes in muscle morphologic and enzymatic adaptation. Increased prolyl 4-hydroxylase activity could suggest muscle damage caused by electrically induced muscle contractions.

Repair of partial quadriceps tendon rupture. Observations in 28 cases.

We operated on 28 patients with partial rupture of the quadriceps tendon. A simple excision of the scar tissue and closure of the tendon gave an excellent or good result in 25 patients. Ultrasonography was useful to confirm the diagnosis.

Operative treatment of partial rupture of the patellar ligament. A study of 138 cases.

One hundred and thirty eight knees of 124 patients with partial rupture of the patellar ligament were treated surgically after failure to heal them by conservative means. Ultrasonography was used to confirm the diagnosis in 45 knees, and when positive it had a good correlation with the operative findings. During surgery excision of the devitalized tissue in the patellar tendon was performed. Histologic examination of the removed tissue revealed degenerated, fibrotic tissue with neo-vascularization, and slight to moderate inflammation resembling devitalized tissue. The patients were re-examined 18.6 +/- 15.0 months post-operatively. Ninety-seven patients (111 knees = 80.4%) benefitted from the operation with excellent or good results. Thirteen knees had to be re-operated with more radical excision due to renewed symptoms. In conclusion, surgical excision of the devitalized tissues gives a good functional result in most of the cases in which non-operative treatment with rest and physical treatment has failed, helping the athlete to return to his pre-injury activities.

Neural control of cardiovascular responses and of ventilation during dynamic exercise in man.

1. Nine subjects performed dynamic knee extension by voluntary muscle contractions and by evoked contractions with and without epidural anaesthesia. Four exercise bouts of 10 min each were performed: three of one-legged knee extension (10, 20 and 30 W) and one of two-legged knee extension at 2 x 20 W. Epidural anaesthesia was induced with 0.5% bupivacaine or 2% lidocaine. Presence of neural blockade was verified by cutaneous sensory anaesthesia below T8-T10 and complete paralysis of both legs. 2. Compared to voluntary exercise, control electrically induced exercise resulted in normal or enhanced cardiovascular, metabolic and ventilatory responses. However, during epidural anaesthesia the increase in blood pressure with exercise was abolished. Furthermore, the increases in heart rate, cardiac output and leg blood flow were reduced. In contrast, plasma catecholamines, leg glucose uptake and leg lactate release, arterial carbon dioxide tension and pulmonary ventilation were not affected. Arterial and venous plasma potassium concentrations became elevated but leg potassium release was not increased. 3. The results conform to the idea that a reflex originating in contracting muscle is essential for the normal blood pressure response to dynamic exercise, and that other neural, humoral and haemodynamic mechanisms cannot govern this response. However, control mechanisms other than central command and the exercise pressor reflex can influence heart rate, cardiac output, muscle blood flow and ventilation during dynamic exercise in man.

American football injuries in Finland.

American football is currently played in 14 European countries. It is a contact sport where injuries are inevitable. In this study, injuries causing more than one week of absence from game or practise were registered during the 1991 preseason and season. A total of 112 injuries was reported among 684 players. Knees were most vulnerable to injury (28.6%) followed by ankle injuries (16.7%). Operations were performed on 28 (25%) of the injured players. Catastrophic injuries can occur in this sport, but none has happened in Finland during the 12 years for which the sport has been practised. The skill level was not a contributing factor. The frequency of injuries and their profile closely resemble those in US-based studies so it is suggested that the precautions and preventive measures recommended in the USA should be applied and followed in Europe.

Basal concentrations of anabolic and catabolic hormones in relation to endurance exercise after short-term changes in diet.

This study aimed to use a classical model to analyse whether alterations in performance due to short-term changes in diet are reflected in peripheral basal anabolic and catabolic hormone concentrations. Six healthy students (two women and four men) performed a cross-over study including three test situations. The reference test was preceded by each subject's normal unrestricted diet of western type (N). After this, three of the subject's were provided a carbohydrate-rich diet (CHO) for 3 days followed by the second test. Following this test, a carbohydrate deficient, protein/fat rich diet (F) was provided for another 3 days followed by the third test. The remaining three subjects had these diets in reverse order. Basal concentrations of cortisol (C), sex hormone-binding globulin (SHBG), insulin-like growth factor (IGF-I), total-testosterone and non-SHBG-bound-testosterone (NST), the NST:C ratio and an ergometer cycle endurance test with measurements of submaximal as well as measurements of maximal oxygen uptake, heart rate, respiratory exchange ratio (R), free fatty acids (FFA), glycerol and lactate were investigated. All the subjects were involved in athletics for recreation and during the study they performed daily physical exercise according to their normal routine. After the F diet only two of the subjects completed the test. One woman dropped out after 16 min, two men dropped out after 14 min and one after 13 min of cycling. After the CHO diet all six subjects completed the ergometer cycle test. Considering the whole group, there were no significant differences in lactate or glycerol concentrations during the study.(ABSTRACT TRUNCATED AT 250 WORDS)