Patients that maintain their pre-injury level of physical activity 3-5 years after ACL reconstruction are, 18 months after surgery, characterised by higher levels of readiness to return to sport.

PURPOSE: To characterise patients who had returned to their pre-injury physical activity (PA) or higher at 18 months and maintained that level of PA 3-5 years after the primary ACL reconstruction and to describe the level, frequency, and type of PA participation during the first 5 years after ACL reconstruction  METHOD: Data, from follow-ups at 18 months and 3-5 years after an ACL reconstruction, were extracted from a rehabilitation-specific register. Patients, 15-65 years of age, were included. The data comprised patient-reported outcomes and the results from two questions with respect to the level, frequency, and type of PA. Comparisons were made between patients who had and had not maintained their pre-injury level of PA at the follow-up 3-5 years after an ACL reconstruction. RESULTS: A total of 272 patients met the inclusion criteria. The mean follow-up time was 3.8 years (min-max: 2.9-5.1) after the ACL reconstruction. Of patients who had returned to their pre-injury or a higher level of PA at the 18 month follow-up (n = 114), 68% (n = 78) maintained that level at the 3- to 5-year follow-up after ACL reconstruction. These patients reported a higher level of psychological readiness to return to sport (98 versus 79; p = 0.013). Moreover, these patients were 6.0 years older (p = 0.016) and were characterised by male sex (56% versus 44%; p = 0.028) and a lower level of pre-injury PA (p = 0.013). At the follow-up 3-5 years after the ACL reconstruction, more than 90% met the recommendations for PA. However, the prevalence of physical inactivity had increased and the involvement in organised PA had decreased compared with the 18-month follow-up. CONCLUSIONS: Two out of three patients who have returned to their previous level of PA at 18 months can be expected to maintain that level, 3-5 years following ACL reconstruction. These patients were mainly characterised by a higher level of psychological readiness, especially in patients who participated in knee-strenuous sport and were younger than 20 years of age. The results of this study suggest that patients become more physically inactive over time, implicating the importance of clinicians helping patients find a suitable PA that may help patients maintain an active lifestyle.

Validation of an 18-item version of the Swedish Knee Self-Efficacy Scale for patients after ACL injury and ACL reconstruction.

PURPOSE: To evaluate the measurement properties of a new version of the Swedish Knee Self-Efficacy Scale (K-SES) in samples of individuals with an anterior cruciate ligament (ACL) injury and after ACL reconstruction. A secondary aim was to translate the new version of K-SES into English in order to prepare for future complete cross-cultural adaptation. METHODS: The reliability, structural validity, internal consistency and construct validity of the new, 18-item version of the K-SES (K-SES18) were assessed according to the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist for evaluating methodological quality. The Swedish version of the K-SES18 was translated to English using recommended guidelines. RESULTS: The test-retest reliability for the K-SES18 subscale present and the K-SES18 subscale future showed an Interclass Correlation Coefficient (ICC) = 0.92. In addition, the K-SES18 had a Cronbach's α ranging from 0.93 to 0.96 for the K-SES18 subscale present and from 0.81 to 0.91 for the K-SES18 subscale future. No floor and ceiling effects were identified for the subscale present or the subscale future of the K-SES18. A factor analysis produced 2 factors of importance; K-SES18present and K-SES18future. Seven predefined hypotheses were confirmed. CONCLUSION: The K-SES18 has acceptable reliability and validity to assess knee self-efficacy in patients up to 18 months after ACL injury and reconstruction. LEVEL OF EVIDENCE: IV.

Outcome after hip arthroscopy for femoroacetabular impingement in 289 patients with minimum 2-year follow-up.

Femoroacetabular impingement (FAI) is a common cause of hip pain and dysfunction. The purpose of this study was to report outcome 2 years after the arthroscopic treatment of FAI using validated outcome measurements. Two hundred and eighty-nine patients (males = 190, females = 99) with a mean age of 37 years underwent arthroscopic surgery for FAI. Patients were included consecutively in a hip arthroscopy registry. The cohort was evaluated using online web-based validated health-related patient-reported outcomes measurements, including the iHOT-12, HAGOS, EQ-5D, HSAS for physical activity level, VAS for overall hip function and overall satisfaction. The mean follow-up time was 25.4 months. Pre-operative scores compared with those obtained at follow-up revealed statistically and clinically significant improvements (P < 0.05) for all measured outcomes; iHOT-12 (43 vs 66), VAS for global hip function (50 vs 71), HSAS (2.9 vs 3.6), EQ-5D index (0.58 vs 0.75), EQ-VAS (67 vs 75) and HAGOS different subscales (56 vs 76, 51 vs 69, 60 vs 78, 40 vs 65, 29 vs 57, 33 vs 58). At the 2-year follow-up, 236 patients (82%) reported they were satisfied with the outcome of surgery. We conclude that arthroscopic treatment for FAI resulted in statistically and clinically significant improvements in outcome parameters.

Self-efficacy, symptoms and physical activity in patients with an anterior cruciate ligament injury: a prospective study.

Self-efficacy belief may be of major importance for the outcome of rehabilitation after sports-related injuries. A new instrument, the Knee Self-Efficacy Scale (K-SES), was used to evaluate the role of perceived self-efficacy in patients with an anterior cruciate ligament (ACL) injury. The purpose of this prospective exploratory study was to describe the patients' perceived self-efficacy at various times post-injury and surgery, respectively, for responsiveness of the K-SES and to correlate the K-SES score with the patients' subjective symptoms. The purpose was also to describe the influence of gender, age and physical activity on the patients' perceived self-efficacy. Thirty recently injured patients with an ACL-deficient knee and 33 patients who had undergone ACL reconstruction reported their physical activity level and their perceived self-efficacy on four test occasions during a 1-year period. The patients' subjective knee symptoms were documented on two of the test occasions. A significant increase in the K-SES score was seen after injury as well as after surgery, during the course of rehabilitation. Pre-operatively, men's perceived self-efficacy was significantly (P=0.013) higher compared with women's self-efficacy. Patients with a high baseline (pre-injury) physical activity level (Tegner 7-10) perceived their self-efficacy as being significantly (P=0.005) higher pre-operatively compared with patients with a low baseline activity level (Tegner 3-6). "Younger" (age 17-29), recently injured patients, perceived their self-efficacy as being significantly (P=0.034) higher compared with "older" patients (age 30-54). At the 12-month test, 15 of 30 patients with an ACL-deficient knee and 15 of 33 patients who had undergone ACL reconstruction reported that they had returned or nearly returned to their baseline physical activity level. The subjective knee outcome score, as measured by the Knee Injury and Osteoarthritis Outcome Score (KOOS), improved significantly (P<0.01) during rehabilitation, apart from the KOOS subscale of "pain" (P=0.077) for patients who had undergone ACL reconstruction. There was a "low" to "strong" correlation (r(s)=0.0-0.7) between the K-SES and the five subscales in the KOOS. We conclude from the present study that K-SES has good responsiveness with significantly increased self-efficacy during the rehabilitation process for patients with an ACL-deficient knee as well as for patients who had undergone ACL reconstruction. The improvement in perceived self-efficacy could, however, only be partly explained by the improvement in subjective symptoms. Furthermore, self-efficacy differed significantly with gender, age and physical activity level early in the rehabilitation process.

Injuries and preventive actions in elite Swedish volleyball.

The purpose of this study was to examine the prevalence of injury and the extent of preventive actions in elite Swedish volleyball players. Injuries to players in the elite male and female Swedish division, during the 2002-2003 season, were registered by using a questionnaire. Of the 158 volleyball players (70% response rate), a total of 82 players (52%) reported 121 injuries, during a total exposure time of 24 632 h, representing an overall incidence of 0.77 injuries per player. The majority of the injuries were located in the ankle (23%), followed by the knee (18%) and the back (15%). Most injuries (62%) were classified as being of minor severity. Most injuries occurred during training (47%), and 41% of the injuries had a gradual onset. Fifty-four percent of the injuries that could be related to a specific court situation occurred during blocking, and 30% during spiking. Most players (96%) participated in injury prevention training of some kind, generally performed without supervision (58%). Although most players took part in some kind of preventive action, one out of two players incurred an injury during the season, which indicates that the risk of suffering an injury in elite volleyball is relatively high.

A new instrument for measuring self-efficacy in patients with an anterior cruciate ligament injury.

It has been suggested that self-efficacy belief is of major importance for rehabilitation outcome after sports-related injuries. No instruments are, however, available to evaluate perceived self-efficacy for prognostic and outcome expectations in patients with an anterior cruciate ligament (ACL) injury. Perceived self-efficacy is defined as a judgment of one's potential ability to carry out a task, rather than a measure of whether or not one actually can or does perform the task. The purpose of this study was to develop a reliable and valid instrument for measuring perceived self-efficacy in patients with an ACL injury. A total of 210 male and female patients with an ACL injury were included in this study. The items were generated by health professionals with long clinical experience of patients with an ACL injury and by discussions with patients. After item analysis and item reduction, based on the results from 88 patients, the final 22-item version of the Knee Self-Efficacy Scale (K-SES) was evaluated in 18 patients for test-retest reliability and in 104 patients for internal consistency and validity. The K-SES was compared with the Multidimensional Health Locus of Control (MHLC), Coping Strategies Questionnaire (CSQ), SF-36 and Knee Injury and Osteoarthritis Outcome Score (KOOS) instruments. A factor analysis was also performed on the K-SES. The test-retest revealed a correlation of r(s)=0.73 between test-days and an intraclass correlation coefficient of 0.75. No significant difference between test-days was found. The internal consistency was 0.94, as calculated with Cronbach's alpha. There were low correlations between the K-SES and MHLC and the K-SES and CSQ, respectively. A strong correlation was found between the K-SES and physical functioning, as measured by the SF-36 (r(s)=0.8). All the sub-scales in the KOOS correlated moderately to strongly (r(s)=0.4-0.7) to the K-SES. The factor analysis produced two factors of importance. Factor one was related to how patients perceived their present physical performance/function, while factor two was related to how patients perceived the future physical performance/prognosis of their knee. Good reliability and good face, content, construct and convergent validity were demonstrated for this new instrument (K-SES) for measuring perceived self-efficacy in patients with an ACL injury. The K-SES is recommended for studies designed to evaluate prognostic and outcome expectations of perceived self-efficacy in patients with an ACL-insufficient knee.

Single-leg hop testing following fatiguing exercise: reliability and biomechanical analysis.

A fatiguing exercise protocol was combined with single-leg hop testing to improve the possibilities of evaluating the effects of training or rehabilitation interventions. In the first test-retest experiment, 11 healthy male subjects performed two trials of single-leg hops under three different test conditions: non-fatigued and following fatiguing exercise, which consisted of unilateral weight machine knee extensions at 80% and 50%, respectively, of 1 repetition maximum (1 RM) strength. Intraclass correlation coefficients ranged from 0.75 to 0.98 for different hop test conditions, indicating that all tests were reliable. For the second experiment, eight healthy male subjects performed the fatiguing exercise protocol to investigate how fatigue influences lower-extremity joint kinematics and kinetics during single-leg hops. Hip, knee and ankle joint angles, moments and powers, as well as ground-reaction forces were recorded with a six-camera, motion-capture system and a force platform. Recovery of hop performance following the fatiguing exercise was also measured. During the take-off for the single-leg hops, hip and knee flexion angles, generated powers for the knee and ankle joints, and ground-reaction forces decreased for the fatigued hop conditions compared with the non-fatigued condition (P<0.05). Compared with landing during the non-fatigued condition, hip moments and ground-reaction forces were lower for the fatigued hop conditions (P<0.05). The negative joint power was two to three times greater for the knee than for the hip and five to 10 times greater for the knee than for the ankle during landing for all test conditions (P<0.05). Most measured variables had recovered three minutes post-exercise. It is concluded that the fatiguing exercise protocol combined with single-leg hop testing was a reliable method for investigating functional performance under fatigued test conditions. Further, subjects utilized an adapted hop strategy, which employed less hip and knee flexion and generated powers for the knee and ankle joints during take-off, and less hip joint moments during landing under fatigued conditions. The large negative power values observed at the knee joint during the landing phase of the single-leg hop, during which the quadriceps muscle activates eccentrically, indicate that not only hop distance but also the ability to perform successful landings should be investigated when assessing dynamic knee function.

Iontophoresis with or without dexamethazone in the treatment of acute Achilles tendon pain.

The purpose of this double-blind study was to evaluate the effects of iontophoresis with dexamethazone to iontophoresis with saline solution on patients who had acute (less than 3 months) pain from the Achilles tendon, in terms of range of motion, muscular endurance, pain and symptoms. Twenty-five patients (15 men and 10 women), aged between 18 and 76 years (mean=38), were evaluated before and after 2 weeks of treatment with iontophoresis, as well as after 6 weeks, 3 and 6 months and 1 year. Two groups were treated for 2 weeks with iontophoresis for each treatment. Three ml of dexamethazone were used for the experiment group (n=14) and 3 ml of saline solution for the control group (n=11). Both groups then followed the same rehabilitation programme for 10 weeks. Good reliability was found for the toe-raise and range of motion tests. Poor reliability was, however, found for the pain on palpation test, which was therefore excluded. No difference was found between or within groups for the toe-raise test. Several significant improvements were seen in the experiment group but not in the control group, in the range of motion test, pain during and after physical activity, pain during walking and walking up and down stairs, morning stiffness and tendon swelling. Even though the small sample size limits the possibilities to draw definite conclusions, we conclude from the present study, using a double-blind, randomised approach and a 1-year follow-up period, that positive effects from using iontophoresis with dexamethazone were found in the treatment of patients with acute Achilles tendon pain.

Patellofemoral pain syndrome: pain, coping strategies and degree of well-being.

The purpose of this study was to evaluate how patients with patellofemoral pain syndrome (PFPS) experience their pain, what coping strategies they use for the pain, and their degree of well-being. Fifty patients, 15-52 years old, with PFPS were evaluated with multidimensional pain inventory (MPI), coping strategies questionnaire (CSQ) and Spielberger state trait anxiety inventory (STAI). Reliability of the evaluation methods was established for 12 patients. Good reliability was established for all instruments except for six of the 13 scales of the MPI. Results on MPI, CSQ and STAI are in agreement with the literature on other patient groups with chronic pain. The most frequently used strategies were "coping self statements" and "ignoring sensations". High scores were found for the strategy "catastrophizing" compared with other patient groups having chronic pain. The STAI scores were in general found to be somewhat higher than the scores found in the literature on healthy subjects. It is concluded that the way patients with PFPS experience their pain, the coping strategies for pain they use and their degree of well-being, are in agreement with other patient groups who have chronic pain. Some concern is raised in terms of the high scores reported for the coping strategy "catastrophizing" .

Eccentric overload training for patients with chronic Achilles tendon pain--a randomised controlled study with reliability testing of the evaluation methods.

The purpose was to examine the reliability of measurement techniques and evaluate the effect of a treatment protocol including eccentric overload for patients with chronic pain from the Achilles tendon. Thirty-two patients with proximal achillodynia (44 involved Achilles tendons) participated in tests for reliability measures. No significant differences and strong (r=0.56-0.72) or very strong (r=0.90-0.93) correlations were found between pre-tests, except for the documentation of pain at rest (P<0.008, r=0.45). To evaluate the effect of a 12-week treatment protocol for patients with chronic proximal achillodynia (pain longer than three months) 40 patients (57 involved Achilles tendons) with a mean age of 45 years (range 19-77) were randomised into an experiment group (n=22) and a control group (n=18). Evaluations were performed after six weeks of treatment and after three and six months. The evaluations (including the pre-tests), performed by a physical therapist unaware of the group the patients belonged to, consisted of a questionnaire, a range of motion test, a jumping test, a toe-raise test, a pain on palpation test and pain evaluation during jumping, toe-raises and at rest. A follow-up was also performed after one year. There were no significant differences between groups at any of the evaluations, except that the experiment group jumped significantly lower than the control group at the six-week evaluation. There was, however, an overall better result for the experiment group with significant improvements in plantar flexion, and reduction in pain on palpation, number of patients having pain during walking, having periods when asymptomatic and having swollen Achilles tendon. The controls did not show such changes. Furthermore, at the one-year follow-up there were significantly more patients in the experiment group, compared with the control group, that were satisfied with their present physical activity level, considered themselves fully recovered, and had no pain during or after physical activity. The measurement techniques and the treatment protocol with eccentric overload used in the present study can be recommended for patients with chronic pain from the Achilles tendon.

Ability of closed and open kinetic chain tests of muscular strength to assess functional performance.

The purpose of this study was to investigate the ability of closed and open kinetic chain tests of muscular strength to assess functional performance. Sixteen healthy male subjects, with a mean (+/-SD) age, body mass and height of 27+/-5 years, 78+/-9 kg and 183+/-9 cm, respectively, volunteered to participate in the study. In the closed kinetic chain test (involving muscles working across multiple joints), the subjects performed a 3 repetition maximum (3 RM) barbell squat. The open kinetic chain test (involving muscles working across a single joint) consisted of a concentric isokinetic knee extension at an angular velocity of 60 degrees/s, and was performed using a Kinetic Communicator II dynamometer. The test of functional performance (vertical jump) was performed with the subject standing erect, quickly performing a countermovement jump for maximal height. Moderately strong significant (P<0.05) correlations between the test of functional performance and the closed and open kinetic chain tests of muscular strength were noted, r=0.51 and r=0.57, respectively. It is suggested that the effect of training or rehabilitation interventions should not be based exclusively on tests of muscular strength. Rather, various forms of dynamometry including functional performance tests could be recommended.

A 7-year study on risks and costs of knee injuries in male and female youth participants in 12 sports.

Knee injuries are common and account in various sports for 15-50% of all sports injuries. The cost of knee injuries is therefore a large part of the cost for medical care of sports injuries. Furthermore, the risk of acquiring a knee injury during sports is considered higher for females than for males. The nationwide organization "Youth and Sports" represents the major source of organized sports and recreation for Swiss youth and engages annually around 370000 participants in the age group of 14 to 20 years. The purpose of this study was to combine data on knee injuries from two sources, the first being data on the exposure to risk found in the activity registration in "Youth and Sports" and the second injuries with their associated costs resulting from the activities and filed at the Swiss Military Insurance. This allowed calculation of knee injury incidences, to compare risks between males and females and to estimate the costs of medical treatment. The study comprises 3864 knee injuries from 12 sports during 7 years. Females were significantly more at risk in six sports: alpinism, downhill skiing, gymnastics, volleyball, basketball and team handball. The incidences of knee injuries and of cruciate ligament injuries in particular, together with the costs per hour of participation, all displayed the same sports as the top five for both females and males: ice hockey, team handball, soccer, downhill skiing and basketball. Female alpinism and gymnastics had also high rankings. Knee injuries comprised 10% of all injuries in males and 13% in females, but their proportional contribution to the costs per hour of participation was 27% and 33%, respectively. From this study it can be concluded that females were significantly more at risk for knee injuries than males in six sports and that knee injuries accounted for a high proportion of the costs of medical treatment.

Patellofemoral pain syndrome: a review of current issues.

There is no clear consensus in the literature concerning the terminology, aetiology and treatment for pain in the anterior part of the knee. The term 'anterior knee pain' is suggested to encompass all pain-related problems. By excluding anterior knee pain due to intra-articular pathology, peripatellar tendinitis or bursitis, plica syndromes, Sinding Larsen's disease, Osgood Schlatter's disease, neuromas and other rarely occurring pathologies, it is suggested that remaining patients with a clinical presentation of anterior knee pain could be diagnosed with patello-femoral pain syndrome (PFPS). Three major contributing factors of PFPS are discussed: (i) malalignment of the lower extremity and/or the patella; (ii) muscular imbalance of the lower extremity; and (iii) overactivity. The significance of lower extremity alignment factors and pathological limits needs further investigation. It is possible that the definitions used for malalignment should be re-evaluated, as the scientific support is very weak for determining when alignment is normal and when there is malalignment. Consequently, pathological limits must be clarified, along with evaluation of risk factors for acquiring PFPS. Muscle tightness and muscular imbalance of the lower extremity muscles with decreased strength due to hypotrophy or inhibition have been suggested, but remain unclear as potential causes of PFPS. Decreased knee extensor strength is a common finding in patients with PFPS. Various patterns of weaknesses have been reported, with selective weakness in eccentric muscle strength, within the quadriceps muscle and in terminal knee extension. The significance of muscle function in a closed versus open kinetic chain has been discussed, but is far from well investigated. It is clear that further studies are necessary in order to establish the significance of various strength deficits and muscular imbalances, and to clarify whether a specific disturbance in muscular activation is a cause or an effect (or both) of PFPS. The most common symptoms in patients with PFPS are pain during and after physical activity, during bodyweight loading of the lower extremities in walking up/down stairs and squatting, and in sitting with the knees flexed. However, the source of patellofemoral pain in patients with PFPS cannot be sufficiently explained. There are several types of clinical manifestation of pain, and therefore a differentiated documentation of the patient's pain symptoms is necessary. The connection between strength, pain and inhibition, as well as between personality and pain, needs further investigation. Many different treatment protocols are described in the literature and recent studies advocate a comprehensive treatment approach allowing for an individual and specifically designed treatment. Surgical treatment is rarely indicated. It is strongly suggested that, when presenting studies on PFPS, a detailed description should be provided of the diagnosis, inclusion and exclusion criteria of the patients should be specified along with a detailed methodology, and the conclusions drawn should be compared with those of other studies in the published literature. As this is not the case in most studies on PFPS found in the literature, it is only possible to make general comparisons. In order to further develop treatment models for PFPS we advocate prospective, randomised, controlled, long term studies using validated outcome measures. However, there is a strong need for basic research on the nature and aetiology of PFPS in order to better understand this mysterious syndrome.

Comparison of muscle and tendon stiffness, jumping ability, muscle strength and fatigue in the plantar flexors.

An isokinetic dynamometer was used to measure plantar flexion muscle strength at 60 degrees/s and 200 degrees/s in 10 healthy young men (mean age 25 years). Muscle and tendon stiffnesses were determined on the dynamometer by the use of electrical stimulation and passive stretch (200 degrees/s). Differences in jumping heights between squat and counter-movement jumps were calculated from flight times. The number of heel-rises performed until exhaustion, standing on one leg, were counted. Stepwise regression analysis showed that differences in jumping height increased with lower muscle strength and with higher muscle and tendon stiffnesses, indicating that elastic components may be of more importance in persons with lower muscle strength. The number of heel-rises was negatively dependant on tendon stiffness, indicating that increased stiffness may enhance the development of fatigue.

Muscle fatigue in a standing heel-rise test.

The fatigue process of the triceps surae was evaluated during a standing heel-rise test, comprising of eccentric and concentric muscle actions. Ten healthy women with a mean age of 24 years participated. The heel-rise test was performed until exhaustion. Work and electromyographic activity expressed as root mean square and mean power frequency of the gastrocnemius and soleus muscles were calculated. The average number of heel-rises performed was 25 +/- 1. Work decreased significantly during the test. Mean power frequency decreased significantly in both phases. During the eccentric phase the decrease was significantly larger in the gastrocnemius than in the soleus muscle. There were no significant changes in root mean square except for a decrease in the soleus muscle during the eccentric phase. The present results, showing different fatigue patterns in the two muscles, could be used as reference when testing the fatigue process in different clinical conditions. Recommendations for standardization of a heel-rise test are given.

Weight training of the thigh muscles using closed vs. open kinetic chain exercises: a comparison of performance enhancement.

Resistance training is commonly used in sports for prevention of injuries and in rehabilitation. The purpose of this study was to compare closed vs. open kinetic chain weight training of the thigh muscles and to determine which mode resulted in the greatest performance enhancement. Twenty-four healthy subjects were randomized into a barbell squat or a knee extension and hip adduction variable resistance weight machine group and performed maximal, progressive weight training twice a week for 6 weeks. All subjects were tested prior to training and at the completion of the training period. A barbell squat 3-repetition maximum, an isokinetic knee extension 1-repetition maximum, and a vertical jump test were used to monitor effects of training. Significant improvements were seen in both groups in the barbell squat 3-repetition maximum test. The closed kinetic chain group improved 23 kg (31%), which was significantly more than the 12 kg (13%) seen in the open kinetic chain group. In the vertical jump test, the closed kinetic chain group improved significantly, 5 cm (10%), while no significant changes were seen in the open kinetic chain group. A large increase of training load was observed in both subject groups; however, improvements in isotonic strength did not transfer to the isokinetic knee extension test. The results may be explained by neural adaptation, weight training mode, and specificity of tests.

Fatigue during repeated eccentric-concentric and pure concentric muscle actions of the plantar flexors.

OBJECTIVE: To compare the fatigue development during pure concentric actions with eccentric-concentric actions in standardized isokinetic, open-chain conditions. DESIGN: The study was performed with measurement of muscular strength and EMG of the plantar flexors on an isokinetic dynamometer. BACKGROUND: Fatigue development on a dynamometer has mostly been studied with repeated pure concentric actions. Eccentric-concentric actions are, however, often used in normal activities. An eccentric action has an immediate effect on a following concentric action and therefore it is of interest to follow the fatigue process in repeated combined actions. METHODS: Ten healthy young women participated. The pure concentric test was performed with the same number of cycles as in the eccentric-concentric test, which was performed until exhaustion. Development of MPF and RMS of the EMG in the triceps surae, as well as work, were evaluated. RESULTS: The total amount of work was significantly higher in the eccentric-concentric test than in the pure concentric test. The work decreased similarly (32-39%) with no significant difference between the two tests. A significant decrease (12-16%) in MPF was only seen in the eccentric-concentric test. No changes in RMS were seen. CONCLUSION: The similar reductions of work seen in both tests should primarily be sought in the contractile process as such. Changes in MPF may then be viewed as a phenomenon dependent on the timing of the duty cycle. RELEVANCE: The eccentric-concentric test lead to exhaustion and showed EMG changes and should therefore be recommended when evaluating the development of fatigue in muscular performances in different groups of patients.

A comprehensive treatment approach for patellofemoral pain syndrome in young women.

BACKGROUND AND PURPOSE: The purposes of this study were (1) to evaluate a comprehensive treatment approach for patients with patellofemoral pain syndrome and (2) to compare a training program using isometric muscle contractions with a training program using eccentric muscle contractions. SUBJECTS: Forty female patients with patellofemoral pain syndrome, aged 15 to 28 years (mean = 20.2, SD = 3.2), were randomly assigned to either a group using isometric muscle contractions or a group using eccentric muscle contractions. METHODS: The effects of 12 weeks of treatment, consisting of an educational component and a training program, on physical activity, pain, and muscle function were evaluated after 3 and 12 months. RESULTS: No differences were found between the two groups, except in one of the torque measurements. A reduction in pain and improvements in torque, vertical jumping ability, and physical activity level were seen in both groups after treatment. At the 12-month follow-up, 85% of the subjects were participating in sports without pain and 37 subjects rated their overall knee function as excellent or good. CONCLUSION AND DISCUSSION: The results indicate that the improvements shown in this study may be due to spontaneous recovery over time, the education given to the subjects, the pain monitoring system, the gradually progressing training program, and the adjusted physical activity. [Thomeé R. A. Comprehensive treatment approach for patellofemoral pain syndrome in young women.