Unfolding the outcomes of surgical treatment of lumbar spinal stenosis-a prospective 5- and 10-year follow-up study.

PURPOSE: In this prospective study, we aim to determine surgical outcomes in patients with lumbar spinal stenosis (LSS) 10 years after surgery. METHODS: The study population consisted of 96 LSS patients who underwent decompressive surgery, 72 of whom participated in the 10-year follow-up. The patients completed a questionnaire preoperatively and 3 months, 5 years, and 10 years postoperatively. Outcome measures were satisfaction with the surgical outcomes, the Oswestry Disability Index (ODI), the visual analog scale (VAS), the numeric rating scale (NRS-11), and walking ability quantified in meters. Postoperative improvements at 5 and 10 years were analyzed using linear mixed models. Furthermore, comparisons between postoperative time points were made for clinical courses of pain, disability, and walking ability. RESULTS: At the 10-year follow-up, 68% of the patients were satisfied with the surgical outcomes. All the measured outcomes showed statistically significant improvement from baseline to the 5- and 10-year follow-up. The mean VAS score was 9.8 mm higher at the 5-year follow-up and 7.8 mm at the 10-year follow-up compared to the 3-month follow-up point. Similarly, the mean ODI was 4.8% higher at the 10-year follow-up compared to the 3-month follow-up point. CONCLUSION: This study reports the clinical course of pain, disability, and walking distance after LSS surgery with the 10-year follow-up. Based on our study results, patients with LSS could expect to have positive effects of their back surgery up to 10 years. However, minor worsening in pain and disability may occur and one-fourth of the patients may need a reoperation during the 10-year follow-up period.

Relationship of body anthropometric measures with skeletal muscle mass and strength in a reference cohort of young Finnish women.

OBJECTIVES: 1) To study if limb length explains variability in appendicular and total muscle mass better than height and 2) if muscle mass adjusted for limb length rather than height correlates better with grip and knee extension strength. METHODS: 400 healthy women aged 20-40 were recruited as a reference population. Body composition, limb length, grip strength and knee extension strength were measured. New relative muscle mass indexes were computed by adjusting upper limb muscle mass for upper limb length (ULRSMI) and lower limb muscle mass for lower limb length (LLRSMI). RESULTS: Height correlated strongest with all muscle mass measures. Height had the highest R² values for predicting variability in appendicular skeletal muscle mass (0.33), upper limb skeletal muscle mass (0.20), lower limb skeletal muscle mass (0.34) and total skeletal muscle mass (0.36). Correlation of relative skeletal muscle mass index (RSMI) with grip and knee extension strength (r=0.47 and 0.43) was higher when compared with correlation of ULRSMI and LLRSMI with these measures. CONCLUSION: Compared to limb length, height correlates better with regional and total muscle mass. Muscle mass adjusted for height correlates better with grip strength and knee strength when compared with muscle mass adjusted for limb length.

In Vivo MRI Measurement of Spinal Cord Displacement in the Thoracolumbar Region of Asymptomatic Subjects with Unilateral and Sham Straight Leg Raise Tests.

BACKGROUND: Normal displacement of the conus medullaris with unilateral and bilateral SLR has been quantified and the "principle of linear dependence" has been described. PURPOSE: Explore whether previously recorded movements of conus medullaris with SLRs are i) primarily due to transmission of tensile forces transmitted through the neural tissues during SLR or ii) the result of reciprocal movements between vertebrae and nerves. STUDY DESIGN: Controlled radiologic study. METHODS: Ten asymptomatic volunteers were scanned with a 1.5T magnetic resonance (MR) scanner using T2 weighted spc 3D scanning sequences and a device that permits greater ranges of SLR. Displacement of the conus medullaris during the unilateral and sham SLR was quantified reliably with a randomized procedure. Conus displacement in response to unilateral and sham SLRs was quantified and the results compared. RESULTS: The conus displaced caudally in the spinal canal by 3.54±0.87 mm (mean±SD) with unilateral (p≤.001) and proximally by 0.32±1.6 mm with sham SLR (p≤.542). Pearson correlations were higher than 0.99 for both intra- and inter-observer reliability and the observed power was 1 for unilateral SLRs and 0.054 and 0.149 for left and right sham SLR respectively. CONCLUSIONS: Four relevant points emerge from the presented data: i) reciprocal movements between the spinal cord and the surrounding vertebrae are likely to occur during SLR in asymptomatic subjects, ii) conus medullaris displacement in the vertebral canal with SLR is primarily due to transmission of tensile forces through the neural tissues, iii) when tensile forces are transmitted through the neural system as in the clinical SLR, the magnitude of conus medullaris displacement prevails over the amount of bone adjustment.

Menthol concentration in topical cold gel does not have significant effect on skin cooling.

BACKGROUND: Topical menthol gels are used in the treatment of various pain conditions. However, the effect of the menthol concentration to skin cooling or cooling sensation is not clear. We hypothesized that increasing menthol concentration enhances skin cooling and causes elevated cooling sensation. METHODS: Ten healthy male volunteers (age range 25-30 years) were recruited for this study. Application of three gels with different menthol concentrations (0.5%, 4.6% and 10.0%) was tested in random sequence on the left thigh of the subjects. Skin cooling was recorded with a digital infrared camera (FLIR Systems Inc., USA), and cooling sensation was measured with the visual analogue scale rating. RESULTS: All gels decreased skin temperature significantly (P < 0.05) at least for one hour. However, the variation in menthol concentration seemed not to have a significant effect on skin cooling. Subjects experienced that gel with 4.6% menthol concentration caused significantly stronger cooling effect than 0.5% and 10.0% gels. Gel application had no significant effect on skin temperature in surrounding skin areas. CONCLUSION: In contrast to our hypothesis, menthol concentration was not connected to skin cooling, while moderate menthol concentration of 4.6% may induce stronger cooling sensation compared to low (0.5%) or high (10.0%) concentration gels.

EMG signal morphology and kinematic parameters in essential tremor and Parkinson's disease patients.

The aim of this work was to differentiate patients with essential tremor from patients with Parkinson's disease. Electromyographic data from biceps brachii muscles and kinematic data from arms during isometric tension of the arms were measured from 17 patients with essential tremor, 35 patients with Parkinson's disease and 40 healthy controls. The EMG signals were divided to smaller segments from which histograms were calculated. The histogram shape was analysed with a feature dimension reduction method, the principal component analysis, and the shape parameters were used to differentiate between different subject groups. Three parameters, RMS-amplitude, sample entropy and peak frequency were determined from the kinematic measurements of the arms. The height and the side differences of the histogram were the most effective for differentiating between essential tremor and Parkinson's disease groups. The histogram parameters of patients with essential tremor were more similar to patients with Parkinson's disease than healthy controls. With this method it was possible to discriminate 13/17 patients with essential tremor from 26/35 patients with Parkinson's disease and 14/17 patients with essential tremor from 29/40 healthy controls. The kinematic parameters of patients with essential tremor were closer to parameters of patients with Parkinson's disease compared to healthy controls. Combining EMG and kinematic analysis did not increase discrimination efficiency but provided more reliability to the discrimination of subject groups.

Dynamic tension EMG to characterize the effects of DBS treatment of advanced Parkinson's disease.

Deep brain stimulation (DBS) is an effective treatment method for motor symptoms of advanced Parkinson's disease. DBS-electrode is implanted to subthalamic nucleus to give precisely allocated electrical stimuli to brain. The optimal stimulus type has to be adjusted individually. Disease severity, main symptoms and biological factors play a role in correctly setting up the device. Currently there are no objective methods to assess the efficacy of DBS, hence the adjustment is based solely on clinical assessment. In optimal case an objectively measurable feature would point the right settings of DBS. Surface electromyographic and kinematic measurements have been used in Parkinson's disease research. As Parkinson's disease symptoms are known to change the EMG signal properties, these methods could be helpful aid in the clinical adjustment of DBS. In this study, 13 patients with advanced Parkinson's disease who received DBS treatment were measured. The patients were measured with seven different settings of the DBS in clinical range including changes in stimulation amplitude, frequency and pulse width. The EMG analysis was based on parameters that characterize EMG signal morphology. Correlation dimension and recurrence rate made the most significant difference in relation to optimal settings. In conclusion, EMG analysis is able to detect differences between the DBS setups, and can help in finding the correct parameters.

EMG signal morphology in essential tremor and Parkinson's disease.

The aim of this work was to differentiate patients with essential tremor from patients with Parkinson's disease. The electromyographic signal from the biceps brachii muscle was measured during isometric tension from 17 patients with essential tremor, 35 patients with Parkinson's disease, and 40 healthy controls. The EMG signals were high pass filtered and divided to smaller segments from which histograms were calculated using 200 histogram bins. EMG signal histogram shape was analysed with a feature dimension reduction method, the principal component analysis, and the shape parameters were used to differentiate between different patient groups. The height of the histogram and the side difference between left and right hand were the best discriminators between essential tremor and Parkinson's disease groups. With this method, it was possible to discriminate 13/17 patients with essential tremor from 26/35 patients with Parkinson's disease and 14/17 patients with essential tremor from 29/40 healthy controls.

Preoperative predictors for good postoperative satisfaction and functional outcome in lumbar spinal stenosis surgery--a prospective observational study with a two-year follow-up.

BACKGROUND AND AIMS: Lumbar spinal stenosis (LSS) is the most frequent indication for back surgery in adults aged over 65 years, but about one-third of operated patients have less than good/excellent results from the operation. Awareness of outcome predictors and their predictive values may help clinicians in their assessment of the prognosis of patients when considering surgical treatment. Our aim was to study the preoperative predictors in LSS for a good postoperative outcome (satisfaction with surgery and functional improvement) with a two-year follow-up. MATERIAL AND METHODS: LSS patients (n = 102) completed a questionnaire preoperatively and on two-year follow-up. Preoperative patient-related predictors, self-rated health, comorbidities and preoperative treatment were assessed. Satisfaction with the surgical outcome was assessed with a seven-category scale; satisfaction was determined to be good if the patient response was "condition has considerably improved" or "totally cured". Other responses ("condition has slightly improved" or worse) represented poorer satisfaction. A good functional outcome was determined as >30% relative improvement compared to the presurgery score in the Oswestry Disability Index (ODI). RESULTS: The predictors for good satisfaction were age < 75 years at operation (OR 4.03; 95% CI 1.35-12.02; p = 0.012) and no previous lumbar operation (OR 3.65; 95% CI 1.13-11.79; p = 0.031). Predictors for a good improvement in the ODI score were regular preoperative analgesic use < 12 months (OR 3.40; 95% CI 1.21-9.53; p = 0.020), non-smoking (OR 3.47; 95% CI 1.09-11.03; p = 0.035) and good (above average) self-rated health (OR 3.27; 95% CI 1.06-10.12; p = 0.039). CONCLUSIONS: In LSS, regular analgesic treatment preoperatively for 12 months or less, self-rated health above average and non-smoking predicted a good postoperative functional improvement. An age under 75 years and no previous lumbar operation predicted good post-operative satisfaction with the surgery.

Linear and nonlinear tremor acceleration characteristics in patients with Parkinson's disease.

The purpose of the study was to evaluate linear and nonlinear tremor characteristics of the hand in patients with Parkinson's disease (PD) and to compare the results with those of healthy old and young control subjects. Furthermore, the aim was to study correlation between tremor characteristics and clinical signs. A variety of nonlinear (sample entropy, cross-sample entropy, recurrence rate, determinism and correlation dimension) and linear (amplitude, spectral peak frequency and total power, and coherence) hand tremor parameters were computed from acceleration measurements for PD patients (n = 30, 68.3 ± 7.8 years), and old (n = 20, 64.2 ± 7.0 years) and young (n = 20, 18.4 ± 1.1 years) control subjects. Nonlinear tremor parameters such as determinism, sample entropy and cross-sample entropy were significantly different between the PD patients and healthy controls. These parameters correlated with the Unified Parkinson's disease rating scale (UPDRS), tremor and finger tapping scores, but not with the rigidity scores. Linear tremor parameters such as the amplitude and the maximum power (power corresponding to peak frequency) also correlated with the clinical findings. No major difference was detected in the tremor characteristics between old and young control subjects. The study revealed that tremor in PD patients is more deterministic and regular when compared to old or young healthy controls. The nonlinear tremor parameters can differentiate patients with PD from healthy control subjects and these parameters may have potential in the assessment of the severity of PD (UPDRS).

Effectiveness of traditional bone setting in treating chronic low back pain: a randomised pilot trial.

OBJECTIVES: The aim of this trial was to establish the effectiveness of traditional bone setting (TBS) compared with conventional physical and exercise therapy (PhT) in treating chronic low back pain (cLBP). DESIGN: Randomised clinical trial. SETTING: Working-aged cLBP patients (n=131, age range 29-51 years) were randomised into two treatment groups: TBS and PhT. Follow-up assessments took place 1, 6 and 12 months after treatment. INTERVENTIONS: TBS is a popular traditional manual mobilisation therapy for musculoskeletal disorders in Finland. Conventional PhT was used as the reference treatment. MAIN OUTCOME MEASURES: LBP intensity (Visual Analog Scale 0-100, VAS), the Oswestry Disability Index (ODI), the global assessment score (scale -1 to +10), a health-related quality of life (HRQoL) assessment and spine mobility measurements were used as measures. RESULTS: 118 patients (95.9%, 59 men and 59 women) completed the treatment program. Both treatments reduced the VAS and ODI levels after 1 month. Changes in VAS did not differ between the two treatment groups (mean -0.2, CI -11.3 to 10.9). The improvement in ODI (mean 2.4, CI -1.2 to 6.0, p=0.069, repeated measurements ANOVA) and quality of life scores (mean -0.03, CI -0.06 to 0, p=0.056) tended to be greater after TBS. Additionally, global assessment scores were better for TBS-treated patients (Mann-Whitney test, p=0.001). There were no differences between the spine mobility test results of the two groups. Changes in both VAS (mean -2.4, CI -15.5 to 10.6) and ODI (mean 1.0, CI -3.0 to 5.1) measures did not, however, differ between the groups at the 1-year follow-up stage. CONCLUSIONS: Most cLBP patients found the treatments to be beneficial. Although the long-term dynamics of pain and disability did not differ between the groups, the subjective benefits appeared to be more significant after TBS.

Novel parameters of surface EMG in patients with Parkinson's disease and healthy young and old controls.

The aim of this study was to evaluate a variety of traditional and novel surface electromyography (SEMG) characteristics of biceps brachii muscle in patients with Parkinson's disease (PD) and compare the results with the healthy old and young control subjects. Furthermore, the aim was to define the optimal biceps brachii loading level that would most likely differentiate patients from controls. The results indicated that such nonlinear SEMG parameters as %Recurrence, %Determinism and SEMG distribution kurtosis, correlation dimension and sample entropy were significantly different between the PD patients and healthy controls. These novel nonlinear parameters, unlike traditional spectral or amplitude parameters, correlated with the Unified Parkinson's Disease Rating Scale (UPDRS) and finger tapping scores. The most significant between group differences were found in the loading condition where no additional weights were applied in isometric elbow flexion. No major difference of SEMG characteristics was detected between old and young control subjects. In conclusion, the novel SEMG parameters can differentiate the patients with PD from healthy control subjects and these parameters may have potential in the assessment of the severity of PD.

Muscle hypertrophy, strength development, and serum hormones during strength training in elderly women with fibromyalgia.

OBJECTIVE: To examine the effects of strength training on maximal force, cross-sectional area (CSA), and electromyographic (EMG) activity of muscles and serum hormone concentrations in elderly females with fibromyalgia (FM). METHODS: Twenty-six patients with FM were randomly assigned to a training (FMT; n = 13; mean age 60 years) or a control (FMC; n = 13; 59 years) group. FMT performed progressive strength training twice a week for 21 weeks. The measurements included maximal isometric and concentric leg extension forces, EMG activity of the vastus lateralis and medialis, CSA of the quadriceps femoris, and serum concentrations of testosterone (T), free testosterone (FT), growth hormone (GH), insulin-like growth factor-1 (IGF-1), dehydroepiandrosterone sulfate (DHEAS), and cortisol. Subjectively perceived symptoms of FM were also assessed. RESULTS: All patients were able to complete the training. In FMT strength training led to increases of 36% (p<0.001) and 33% (p<0.001) in maximal isometric and concentric forces, respectively. The CSA increased by 5% (p<0.001) and the EMG activity in isometric action by 47% (p<0.001) and in concentric action by 57% (p<0.001). Basal serum hormone concentrations remained unaltered during strength training. The subjective perceived symptoms showed a minor decreasing tendency (ns). No statistically significant changes occurred in any of these parameters in FMC. CONCLUSION: Progressive strength training increases strength, CSA, and voluntary activation of the trained muscles in elderly women with FM, while the measured basal serum hormone concentrations remain unaltered. Strength training benefits the overall physical fitness of the patients without adverse effects or any exacerbation of symptoms and should be included in the rehabilitation programmes of elderly patients with FM.

Changes in knee extension and flexion force, EMG and functional capacity during strength training in older females with fibromyalgia and healthy controls.

OBJECTIVE: To investigate the effects of strength training on neuromuscular functions in elderly females with fibromyalgia (FM). METHODS: Thirteen females with fibromyalgia [group FMt; mean age (s.d.) 60.2 (2.5) years] and 11 healthy controls [group HCt; 64.2 (2.7) yr] carried out supervised strength training twice a week for 21 weeks. Thirteen FM patients [group FMc; 59.1 (3.5) yr] served as non-training controls. Maximal isometric force and electromyographic (EMG) activity of the right quadriceps femoris in knee extension and flexion actions, maximal 10-m walking speed, and 10-step stair-climbing time were measured. Tender points were assessed by palpation, subjectively perceived symptoms with a visual analogue scale, and the self-reported physical function capacity by Health Assessment Questionnaire (HAQ). RESULTS: The mean (s.d.) increases in maximal extension force during the training period in groups FMt and in HCt were 32 (33)% (P < 0.001) and 24 (12)% (P < 0.001) respectively and those of flexion were 13 (20)% (P < 0.05) and 24 (17)% (P < 0.01). Explosive force of the extensors increased in both FMt and in HCt. The integrated EMGs of the vastus lateralis and medialis muscles increased in both FMt and HCt. Muscle forces and EMGs in group FMc remained at the basal level. Walking speed, stair-climbing time and the HAQ index improved in group FMt. The changes in the number of tender points and in perceived symptoms were in favour of the training group FMt. CONCLUSIONS: The data support the hypothesis that elderly female FM patients have normal neuromuscular function. Supervised strength training also suits elderly FM patients, has positive effects on perceived symptoms and improves functional capacity without complications.

Whiplash injuries in Finland: a prospective 1-year follow-up study.

OBJECTIVES: The aim of the study was to define how many whiplash injuries occur in Finland in traffic accidents and the degree of severity of these injuries using the whiplash-associated disorders (WAD) classification presented by the Quebec Task Force, and to define possible long-term health effects caused by whiplash injury as well as the duration of whiplash-associated sick-leaves. METHODS: This was a prospective one-year-follow-up study. Fourteen insurance companies paving compensations for traffic accidents in Finland sent the accident reports and medical certificates of all neck injuries attributable to traffic accidents to the research team. The material was collected from neck injuries that had occurred in traffic accidents during the year 1998. RESULTS: The majority of those suffering a whiplash injury were women. On the basis of the WAD classification, most whiplash injuries were mild, belonging to grades WAD I and II. At one year from the accident nearly 10% considered that their health had been impaired significantly as a result of their neck injury. Over 10% of those questioned had been on sick-leave for over a month but only 1.5% had been on sick-leave associated with the injury for more than 6 months. The most common symptom after one year was neck pain or neck pain combined with headache and symptoms in the upper extremities. No major changes related to the seasons of the year were found. CONCLUSIONS: The number of reported neck injuries in proportion to all traffic accidents involving physical injuries is small, even in proportion to rear-end collisions. In a considerable proportion of collision patients, whiplash injury does result in significant impairment which can last as long as a year after the accident. The WAD classification predicts the duration of work disability and the long-term health damage caused by the injury. Since the appearance of symptoms and the individual need for rehabilitation due to impaired functional capacity do not depend solely on the tissue damage and biomechanical forces involved in the collision, in the future it will be important to determine which factors are responsible for the differences in coping after a collision.

Segmental lumbar spine instability at flexion-extension radiography can be predicted by conventional radiography.

AIM: To identify plain radiographic findings that predict segmental lumbar spine instability as shown by functional flexion-extension radiography. MATERIALS AND METHODS: Plain radiographs and flexion-extension radiographs of 215 patients with clinically suspected lumbar spine instability were analysed. Instability was classified into anterior or posterior sliding instability. The registered plain radiographic findings were traction spur, spondylarthrosis, arthrosis of facet joints, disc degeneration, retrolisthesis, degenerative spondylolisthesis, spondylolytic spondylolisthesis and vacuum phenomena. Factors reaching statistical significance in univariate analyses (P < 0.05) were included in stepwise multiple logistic regression analysis. RESULTS: Degenerative spondylolisthesis (P = 0.004 at L3-4 level and P = 0.017 at L4-5 level in univariate analysis and odds ratio 16.92 at L4-5 level in multiple logistic regression analyses) and spondylolytic spondylolisthesis (P = 0.003 at L5-S1 level in univariate analyses) were the strongest independent determinants of anterior sliding instability. Retrolisthesis (odds ratio 10.97), traction spur (odds ratio 4.45) and spondylarthrosis (odds ratio 3.20) at L3-4 level were statistically significant determinants of posterior sliding instability in multivariate analysis. CONCLUSION: Sliding instability is strongly associated with various plain radiographic findings. In mechanical back pain, functional flexion-extension radiographs should be limited to situations when symptoms are not explained by findings of plain radiographs and/or when they are likely to alter therapy.

Disc herniation-related back pain impairs feed-forward control of paraspinal muscles.

STUDY DESIGN: A comparative study of lumbar paraspinal muscle reflexes during sudden upper limb loading in healthy control subjects and patients with sciatica. OBJECTIVES: To assess reflex activation of paraspinal muscles during sudden upper limb loading. SUMMARY OF BACKGROUND DATA: Sudden upper limb loading and upper limb voluntary movements cause reflex activation of trunk muscles. A short latency response of approximately 50 msec of lumbar muscles has been observed before, but the reflexes have not been studied in patients with sciatica. METHODS: The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface EMG from 20 patients selected for an operation as a result of disc herniation-related chronic low back pain and 15 back-healthy controls. Pain, disability, and depression scores were recorded. RESULTS: Short latency response of paraspinal muscles for unexpected upper limb loading was similar in healthy controls and patients with sciatica in supported standing. During normal standing anticipation shortened the lumbar reflex latency in healthy controls but not among the patients. CONCLUSIONS: The results provide evidence for impaired feed-forward control of lumbar muscles in patients with sciatica.

Back and abdominal muscle function during stabilization exercises.

OBJECTIVES: To assess the paraspinal and abdominal muscle activities during different therapeutic exercises and to study how load increment produced by varying limb movements and trunk positions could affect these muscle activities. DESIGN: A cross-sectional study comparing muscle activities between men and women. SETTING: Rehabilitation clinic in university hospital. PARTICIPANTS: Twenty-four healthy volunteers (14 women, 10 men) aged 21 to 39 years. INTERVENTIONS: Subjects performed 16 different therapeutic exercises commonly used to treat low back pain. MAIN OUTCOME MEASURES: Surface electromyography was recorded from the paraspinal (T9, L5) and abdominal (rectus abdominis, obliquus externus) muscles during these exercises. Average electromyographic amplitudes obtained during the exercises were normalized to the amplitude in maximal voluntary contraction (% MVC) to produce interindividually comparable muscle activity assessments. RESULTS: Mean average normalized electromyographic amplitudes (% MVC) of the exercises were below 50% MVC. At L5 level, the multifidus muscle activities were significantly higher (p <.05) in women than in men, whereas no significant difference was found at T9 level. Similarly, rectus abdominis and obliquus externus activities were significantly higher (p <.001, p <.05) in women than in men. Load increment in hands or unbalanced trunk and limb movements produced higher paraspinal and abdominal muscle activities (p <.05). CONCLUSIONS: Simple therapeutic exercises are effective in activating both abdominal and paraspinal muscles. By changing limb and trunk positions or unbalancing trunk movements, it is possible to increase trunk muscle activities. Women were better able to activate their stabilizing trunk muscles than men; but it is also possible that men, having a much higher degree of strength on maximal contraction, only need to activate a smaller amount of that maximum to perform a similar activity.

Monitoring of muscle fatigue during isokinetic exercise.

The aim of this study was to evaluate and clarify the usefulness of different spectral characteristics of myoelectrical activity in the follow-up of development of muscle fatigue. Vastus lateralis (part of quadriceps) muscle loaded in a simple isokinetic exertion test was used as a model. Twelve, well trained athletes served as study subjective to minimize the inter-individual variations. They went through one-minute test with isokinetic device at the range of 90 degrees extension and flexion at the level of their maximal force. The myoelectrical signals were registered from middle of the vastus lateralis muscle by a computerized fast Fourier transform analyzing system based on 80286 and 80287 microprocessors and using surface electrodes. Mean power frequency (MPF) was 65.6 (SE=Standard Error, 1.6) Hz, median frequency (MF) 55.8 Hz and zero crossing rate (ZCR) 92.5 (SE 1.5) during first performance. All these parameters decreased apparently linearly and significantly from the beginning of the test (P<0.001). The decrease rate of ZCR was fastest and MF slowest. The area of power spectrum (PSA) was 1753 (SE 320) units during first performance, and it increased markedly with slightly accelerating rate during the test. In conclusion, for the evaluation of the muscular performance during the development of fatigue it is beneficial to monitor simultaneously MPF, MF and ZCR.

Injury profile in ice hockey from the 1970s through the 1990s in Finland.

The aim of this study was to investigate the incidence, types, and mechanisms of injury in Finnish ice hockey players at the highest competition level in different decades. Several teams were observed prospectively during the seasons between 1976 and 1979, and in the 1988 to 1989 and 1992 to 1993 seasons. An injury was defined as any sudden trauma requiring examination and treatment by a physician. The inclusion criteria were the same during the entire study. A total of 641 injuries were recorded. The injury rate per game increased significantly from 54 per 1000 player-hours in the 1970s to 83 per 1000 player-hours in the 1990s. The injury profile in the 1980s and 1990s differed from that in the 1970s. Per 1000 player-years, the rate of contusions as well as of sprains or strains increased significantly with each decade. Checking and unintentional collision with an opponent were common mechanisms of injury throughout the study, and the rate of injury by these mechanisms has continually increased. In conclusion, we suggest that there has been an increase in rough body contact between players, causing an alarming increase in the rate of ice hockey injuries.