An evaluation of knee extensor and knee flexor torques and EMGs in patients with patellofemoral pain syndrome in comparison with matched controls

The relationship between concentric and eccentric isokinetic torques and EMGs of quadriceps and hamstring muscles in patients with unilateral patellofemoral pain was studied in 27 patients (13 males, 14 females). The patients and a group of controls matched for age, gender, and physical activity were tested on a Kin-Com dynamometer at 60⁰/s and 180⁰/s angular velocity. EMGs were recorded for eight of the patients and their matched controls. In addition, the reproducibility of isokinetic measurements made under the same conditions but on different occasions in patients with patellofemoral pain was evaluated. Twenty-one patients (11 males, 10 females) underwent testing of their quadriceps and hamstring muscles two or three times on a Kin-Com dynamometer. This was performed both concentrically and eccentrically in their painful leg while the patients evaluated their knee pain using Borg's pain scale. The data show that the patients had a significantly lower agonist as well as antagonist EMG activity during knee extension measurements in their painful leg compared with the controls. However, there were no differences in either agonist or antagonist EMG activities during knee flexion measurements between the patients and the controls. The quadriceps muscle torque was considerably weaker in the patients' painful leg compared with both their asymptomatic leg and with the controls. Peak torque for knee extension was reached at a mean of 66⁰ of knee flexion for both patients and controls. However, the patients showed a considerably wider range within which they produced their peak torque in their painful leg than in their asymptomatic and also in comparison with the controls. The hamstring muscle torque was weaker in both legs of the patients compared with the controls. There were no significant differences in knee pain according to Borg's pain scale between the isokinetic tests or within the tests. The reproducibility testing yielded no significant differences between the different testing occasions in the two muscle groups. In summary, patients with patellofemoral pain have a greatly reduced agonist and antagonist EMG activity during knee extension in their painful leg. They also have a considerably reduced quadriceps torque. Furthermore, isokinetic testing in patients with patellofemoral pain is a reproducible testing modality.     

Effect of taping the patella on concentric and eccentric torque and EMG of knee extensor and flexor muscles in patients with patellofemoral pain syndrome

The acute effect of patella taping on torque and electromyographic (EMG) activity in maximal voluntary concentric and eccentric action of the knee extensor and flexor muscles in patients with patellofemoral pain syndrome was studied in 48 patients (62 knees). The patients (28 female, 20 male) were tested concentrically and eccentrically on a Kin-Com dynamometer with simultaneous EMG recording with the patella untaped and medially or laterally taped. Patients with clinically normal patellar mobility did not improve their quadriceps performance by taping of the patella: after medial taping they decreased theur muscle torque during concentric work at 60°/s (P<0.05) and eccentric work at 180°/s (P<0.05). After lateral taping they decreased their muscle torque during concentric work at 60°/s (P<0.01), and 180°/s (P<0.05) and eccentric work at both 60°/s (P< 0.01) and 180°/s (P< 0.05). Moreover, these patients also decreased their agonist EMG activity during concentric work at 60°/s (P<0.05) and 180°/s (P<0.05) and their antagonist EMG activity during eccentric work at 60°/s (P<0.01). Patients with a clinical lateral patellar hypermobility increased their knee extensor torque after medial taping at 60°/s during both eccentric work (P<0.01) and concentric work (P<0.05). The greatest improvement in quadriceps performance, however, was in patients with a clinical medial patellar hypermobility. They increased their knee extensor torque after lateral taping during eccentric work at both 60°/s (P<0.001) and 180°/s (P<0.001) and during concentric work at 60°/s (P<0.001). They also increased agonist EMG activity during eccentric work at both 60°/s (P<0.01) and 180°/s (P<0.001) and during concentric work at 180°/s (P<0.05). Patients with both lateral and medial patellar hypermobility increased their knee extensor torque by patellar taping in either direction; after medial taping there was an increase during eccentric work at both 60°/s (P<0.01) and 180°/s (P<0.05) and after lateral taping they also showed an increase during eccentric work at 60°/s (P<0.01). There was a slight decrease in knee flexor torque with either medial or lateral taping in comparison with no taping. Furthermore, there was higher antagonist EMG activity during hamstring measurements when the patella was either medially or laterally taped as opposed to untaped. In all four groups of patients, except for the group with lateral and medial hypermobility, there was a highly significant correlation between patients' own evaluation of the taping and their patellar mobility according to the clinical examination.This study was supported by grants from the Swedish Sports Federation and from Beiersdorf Compancy, Homburg, Germany     

Effects of eccentric versus concentric training on thigh muscle strength and EMG

The purpose of this study was to compare pure eccentric and concentric strength training regarding possible specific effects of muscle action type on neuromuscular parameters, such as a decreased inhibition during maximal voluntary eccentric actions. Two groups of young healthy adult men performed 10 weeks of either eccentric or concentric unilateral isokinetic knee extensor training at 90 degrees.s(-1), 4 sets of 10 maximal efforts, 3 days a week. Knee extensor torque and surface EMG from the quadriceps and hamstring muscle groups were collected and quantified in a window between 30 and 70 degrees knee angle (range of motion 90-5 degrees ) during maximal voluntary eccentric and concentric knee extensor actions at 30, 90, and 270 degrees.s(-1). Changes in strength of the trained legs revealed more signs of specificity related to velocity and contraction type after eccentric than concentric training. No major training effects were present in eccentric to concentric ratios of agonist EMG or in relative antagonist (hamstring) activation. Thus, for the trained leg, the muscle action type and speed specific changes in maximal voluntary eccentric strength could not be related to any effects on neural mechanisms, such as a selective increase in muscle activation during eccentric actions. Interestingly, with both types of training there were specific cross-education effects, that is, action type and velocity specific increases in strength occurred in the contralateral, untrained, leg, accompanied by a specific increase in eccentric to concentric EMG ratio after eccentric training.     

测试体位对髋关节功能运动等速测力结果的影响分析

本实验应用ｋｉｎ－Ｃｏｍ等速装置，通过对不同卧位、头的不同位置、关节不同功能位及手的摆放等形式以探讨测试体位的改变对等速力矩值的影响。３６名男性成年人参加了本实验，并随机分为２组，在６０°／ｓｅｃ角速度下进行了仰卧位、俯卧位髋伸；头正中位、同侧转动、对侧转动时髋屈、髋伸；髋屈９０°、膝屈９０°坐位、髋零位、膝屈９０°仰卧位髋内、外旋及手抓测试平台两侧、手不抓测试平台两侧时髋屈９０°、膝屈９０°坐位髋外旋。结果表明：俯卧位髋伸主要由于该体位时髋伸肌处于较佳的长度而使力矩值显著地大于仰卧位髋伸力矩值。头部的转动造成机体紧张性反射而使髋屈力量大小依次为头转向对侧、头正中位、头转向同侧，髋伸力量大小依次为头转向同侧、头正中位、头转向对侧，但相互之间无显著性差异存在。髋屈９０°、膝屈９０°坐位时，髋内、外旋力量均比髋零位、膝屈９０°仰卧位时要大，其中能内旋力量在两种体位下尚存有显著性差异，造成这一现象的主要原因为解剖方面的因素。手抓测试平台两边与否不致于产生髋外旋力量显著性的差异，其在稳定躯干、骨盆、大腿，使运动轴心相对恒定上有意义。离心收缩力量在测试体位改变时与向心收缩力量有相类似的表现。上述结果有益于等速测试和训?     

Superior results with eccentric compared to concentric quadriceps training in patients with jumper's knee: a prospective randomised study

Background: A recent study reported promising clinical results using eccentric quadriceps training on a decline board to treat jumper''s knee (patellar tendinosis). Methods: In this prospective study, athletes (mean age 25 years) with jumper''s knee were randomised to treatment with either painful eccentric or painful concentric quadriceps training on a decline board. Fifteen exercises were repeated three times, twice daily, 7 days/week, for 12 weeks. All patients ceased sporting activities for the first 6 weeks. Age, height, weight, and duration of symptoms were similar between groups. Visual analogue scales (VAS; patient estimation of pain during exercise) and Victorian Institute of Sport Assessment (VISA) scores, before and after treatment, and patient satisfaction, were used for evaluation. Results: In the eccentric group, for 9/10 tendons patients were satisfied with treatment, VAS decreased from 73 to 23 (p<0.005), and VISA score increased from 41 to 83 (p<0.005). In the concentric group, for 9/9 tendons patients were not satisfied, and there were no significant differences in VAS (from 74 to 68, p<0.34) and VISA score (from 41 to 37, p<0.34). At follow up (mean 32.6 months), patients in the eccentric group were still satisfied and sports active, but all patients in the concentric group had been treated surgically or by sclerosing injections. Conclusions: In conclusion, eccentric, but not concentric, quadriceps training on a decline board, seems to reduce pain in jumper''s knee. The study aimed to include 20 patients in each group, but was stopped at the half time control because of poor results achieved in the concentric group.     

Concentric and eccentric torque comparisons for knee extension and flexion in young adult males and females using the Kinetic Communicator

The purposes of this investigation were to establish average leg torque values as a proportion of body weight for both concentric and eccentric contractions for leg extension and leg flexion, to determine leg flexion/extension ratios for both concentric and eccentric contractions, and to compare those values in males and females from ages 15 to 34 years. The Kinetic Communicator (Kin-Com, Chattecx Corp., Chattanooga, TN), a relatively new computerized strength testing device, was used so that both concentric and eccentric torques could be measured. Pilot study results indicated that Kin-Com results were reliable, r greater than 0.88. Average torque, across the full range of motion, and peak torque expressed in newton meters were divided by body weight in kilograms to produce torque values adjusted by body weight. No differences across age or sex were observed for flexion/extension ratios, but the males' weight-adjusted torque values were significantly (P less than 0.01) greater than the females'. Younger (ages 15 to 24 years) male and female subjects produced significantly (P less than 0.01) greater torque for concentric contractions than older subjects (25 to 34 years). In rehabilitation programs using the Kin-Com, the weight-adjusted torque values and flexion/extension ratios will be useful in determining patients' strength recovery from knee or leg injury and/or surgery.     

Effect of activation force on knee extensor torques

The purpose of this study was to determine whether the magnitude of the activation force, defined as the force that must be applied to the load cell in order to activate the resistance arm of an isokinetic dynamometer, affected knee extensor torques. Twenty-four healthy female subjects performed resisted knee extension through the range of 95 degrees to 5 degrees knee flexion, with a 5-s rest between concentric and eccentric muscle actions. Six exercise sets, composed of the combinations of activation force (20,50, and 100 N) and angular velocity (45 and 135 degrees.s-1), were randomly assigned on each of two occasions, completed within a 10-d period. Although peak torques were not affected by the activation force, average torques, eccentric torques at mid-range (50 degrees knee flexion), and torques during the initial portion of each muscle action (80 degrees knee flexion during concentric muscle actions and 20 degrees flexion during eccentric actions) increased as the activation force increased. The effect of the activation force tended to be more pronounced during eccentric than during concentric muscle actions, and at the faster angular velocity. Comparisons of torques should be based on similar test protocols, including activation force.     

Eccentric muscle action increases site-specific osteogenic response.

PURPOSE: Strain magnitude is known to be a primary determinant of the osteogenic response to loading. However, whether bone adaptation to muscle loading is determined primarily by load magnitude is unclear. The purpose of this study was to determine the contribution of load magnitude from muscle action on the site-specific osteogenic response. METHODS: Twenty young women (12 exercise, 8 control) served as subjects. Bone mineral density (BMD) of the whole body and mid-femur segment and body composition were determined by dual-energy x-ray absorptiometry. Knee extension and flexion strengths were determined on a KinCom dynamometer, with surface electromyography of the vastus lateralis muscle. Exercise subjects trained three times weekly for 18 wk on a KinCom. One leg trained using eccentric knee extension and flexion, and the opposite leg trained using concentric knee extension and flexion. RESULTS: Eccentric exercise demonstrated greater force production with lower integrated electromyographic signal (IEMG) compared with concentric exercise. Significant increases in muscle strength occurred in both exercised legs (P < 0.05), which were of similar relative change. However, only the eccentric trained leg significantly increased mid-femur segment BMD (+3.9%, P < 0.05) and mid-thigh segment lean mass (+5.2%, P < 0.05). CONCLUSIONS: These results suggest that eccentric muscle training is more osteogenic than concentric muscle training and that eccentric training is more efficient by attaining higher force production with lower IEMG.     

Closed kinetic chain alone compared to combined open and closed kinetic chain exercises for quadriceps strengthening after anterior cruciate ligament reconstruction with respect to return to sports: a prospective matched follow-up study

Rehabilitation after anterior cruciate ligament (ACL) reconstruction has focused over the past decade on closed kinetic chain (CKC) exercises due to presumably less strain on the graft than with isokinetic open kinetic chain exercises (OKC); however, recent reports suggest that there are only minor differences in ACL strain values between some CKC and OKC exercises. We studied anterior knee laxity, thigh muscle torque, and return to preinjury sports level in 44 patients with unilateral ACL; group 1 carried out quadriceps strengthening only with CKC while group 2 trained with CKC plus OKC exercises starting from week 6 after surgery. Anterior knee laxity was determined with a KT-1000 arthrometer; isokinetic concentric and eccentric quadriceps and hamstring muscle torque were studied with a Kin-Com dynamometer before and 6 months after surgery. At an average of 31 months after surgery the patients answered a questionnaire regarding their current knee function and physical activity/sports to determine the extent and timing of their recovery. No significant differences in anterior knee laxity were noted between the groups 6 months postsurgery. Patients in group 2 increased their quadriceps torque significantly more than those in group 1, but no differences were found in hamstring torque between the groups. A significantly higher number of patients in group 2 (n=12) than in group 1 (n=5) returned to sports at the same level as before the injury (P<0.05). Patients from group 2 who returned to sports at the same level did so 2 months earlier than those in group 1. Thus the addition of OKC quadriceps training after ACL reconstruction results in a significantly better improvement in quadriceps torque without reducing knee joint stability at 6 months and also leads to a significantly higher number of athletes returning to their previous activity earlier and at the same level as before injury.     

Eccentric and concentric isokinetic moment characteristics in the quadriceps and hamstrings of the chronic isolated posterior cruciate ligament injured knee

OBJECTIVE: Functional strength deficits associated with chronic isolated posterior cruciate ligament (PCL) insufficiency have received limited attention in the literature. The purpose of this study was to determine the eccentric and concentric isokinetic moment characteristics of the quadriceps and hamstrings in a sample of patients with isolated PCL injury. METHODS: Eccentric and concentric mean average and average peak moments were measured for 17 patients with a history of conservatively treated isolated PCL injury using an isokinetic dynamometer. Quadriceps and hamstring isokinetic moments were recorded from 10 degree to 90 degree of knee flexion. Strength ratios were calculated and compared with those reported in the literature for healthy subjects. RESULTS: The hamstrings of the involved side (eccentric/concentric (E/C) ratio = 1.06) were significantly weaker (p<0.05) eccentrically than those of the contralateral side (E/C ratio = 1.29). All hamstrings/quadriceps (H/Q) ratios were less than the universally accepted value of 0.60 and the eccentric H/Q ratio for the injured extremity was significantly lower than the non-injured (p<0.05). In a bilateral comparison, the injured/non-injured (I/N) ratio was less than 1.00 for concentric quadriceps, eccentric quadriceps, and hamstring isokinetic moments. Calculation of the E/C ratio showed that, for the quadriceps, it was 1.08 on the injured side and 1.07 on the non-injured extremity. CONCLUSIONS: Eccentric strengthening should be an integral part of functionally rehabilitating the quadriceps and hamstrings of athletes who suffer from the complications associated with chronic isolated PCL insufficiency.     

Knee isokinetic muscle strength and balance ratio in female soccer players of different age groups: a cross-sectional study

ABSTRACT

Background: As a consequence of years of soccer training and sexual maturation, there is an increase in lower body muscle mass and strength especially in the knee extensors and flexors muscles. In this context, the lack of knee joint stability, resulting from strength imbalance between knee extensor and flexors muscles, has been associated with knee injuries. The aim of this study was to compare the knee flexor and extensor muscle peak torque, average power, contralateral deficit, conventional and functional balance ratios of female soccer players from different age groups.

Methods: Sixty-six female soccer players were divided into four groups: under 13 (U13), under 15 (U15), under 17 (U17) years old and professional (PRO). Flexor and extensor knee muscle strength in concentric and eccentric actions of both limbs were assessed using isokinetic dynamometer.

Results: For the dominant limb, the knee concentric extensor muscles peak torques, assessed at 60 and at 240 deg/sec, and the average power of U15 group were significantly higher than U13 group. Extensor muscle average power of the PRO group was higher than U17. Dominant knee flexor average power of U15 was significantly higher than the U13 group. Peak torque at 60 deg/sec and 240 deg/sec and average power of the PRO group were higher than the U17 group. No differences were found regarding the eccentric action for flexor and extensor muscles. Conventional and functional balance ratios were similar among all age group, except for U13, which presented higher values than the U15 group for the dominant limb.

Conclusions: The greatest improvement in muscular performance occur when the athlete starts practicing soccer (after U13) and when they become professional (after U17) and the balance ratios, and muscle balance ratios remain stable in all age groups, although they are below the recommended level in the literature, which may increase the risk for lower limb injury.     

Isometric and isokinetic knee joint performance in Japanese alpine ski racers.

Isometric and isokinetic (concentric and eccentric, strength of alpine skiers with different performance levels were measured. Nine national (elite, EG) and 10 collegiate (trained, TG) female alpine skiers (16 to 23 years of age) performed maximal voluntary knee extension and flexion. Peak torque was measured at an angular velocity of 30 deg.s-1. The cross-sectional area (CSA) of thigh muscles (quadriceps and hamstring muscles) was determined by an ultrasonic method. No significant differences in anthropometric variables and CSA were observed between EG and TG. EG had significantly greater (p < 0.01 for extensors and p < 0.05 for flexors) eccentric knee extensor and flexor strength than that of TG whereas no significant differences were noted in isometric and concentric strength. Eccentric strength/CSA ratio was also higher for EG than for TG. It was suggested that knee extension and flexion strength during eccentric muscle action might be related to the performance level of alpine skiers.     

Sports massage after eccentric exercise

BACKGROUND: The use of sports massage is very common in the athletic community. However, only a few studies have shown any therapeutic effect of massage. HYPOTHESIS: Sports massage can improve the recovery after eccentric exercise. STUDY DESIGN: Prospective randomized clinical trial. METHODS: Sixteen subjects performed 300 maximal eccentric contractions of the quadriceps muscle bilaterally. Massage was given to 1 leg, whereas the other leg served as a control. Subjects were treated once daily for 3 days. Maximal strength was tested on a Kin-Com dynamometer, and functional tests were based on 1-leg long jumps. Pain was evaluated using a visual analog scale. RESULTS: There was a marked loss of strength and function of the quadriceps directly after exercise and on the third day after exercise. The massage treatment did not affect the level or duration of pain or the loss of strength or function following exercise. CONCLUSION: Sports massage could not improve the recovery after eccentric exercise.     

Relationship among eccentric hip and knee torques, symptom severity and functional capacity in females with patellofemoral pain syndrome

Objective

To determine the relationships between eccentric hip and knee torques, symptom severity and functional capacity in females with patellofemoral pain syndrome (PFPS).

Design

Within-subject correlational study.

Setting

University biomechanics laboratory.

Participants

10 females diagnosed with PFPS.

Main outcome measures

Eccentric strength of the hip abductors and lateral rotators, and knee extensors were assessed using an isokinetic dynamometer. A 10-cm visual analog scale was used to determine usual knee pain in the last week. The Anterior Knee Pain Scale (AKPS) was used to determine the functional capacity of the patients.

Results

The study found that the greater the eccentric knee extensor and hip lateral rotator torques, the higher the functional capacity of the patients (p = 0.02, r = 0.72; p = 0.02, r = 0.72). It was also shown that the greater hip lateral rotator torque, the less the usual pain reported in the last week (p = 0.004, r = −0.84). Despite the lack of statistical significance (p = 0.11), it was also found a modest negative relationship between the eccentric knee extensor torque and the usual pain reported in the last week (r = −0.56) that was considered clinically meaningful (d = 1.4).

Conclusions

This study showed that eccentric knee extensor and hip lateral rotator torques were associated with functional capacity and pain level in females with PFPS. Further investigations should be carried out to verify the effects of an intervention program focused on the eccentric action of these muscles with respect to the symptoms in patients with PFPS.     

Knee flexor strength and rate of torque development deficits in women with patellofemoral pain are related to poor objective function

BackgroundDeficits in knee flexor strength and rate of torque development (RTD) might be present in women with patellofemoral pain (PFP). In addition, maximal strength and RTD of the knee flexors and extensors might be related with subjective and objective function in women with PFP. However, both conjectures are still poorly understood.Research questionDo women with PFP have deficits in the maximal strength and RTD of the knee flexors and extensors during isometric, concentric, and eccentric contractions? Is there a relationship between maximal strength and RTD of the knee flexors and extensors with subjective and objective function in women with PFP?MethodsFifty-six women with, and 46 women without, PFP participated. Maximal strength and RTD (to 30% and 60% maximal torque) during isometric, concentric, and eccentric contractions of the knee flexors and extensors were assessed using an isokinetic dynamometer. Objective assessment included single leg hop test (SLHT) and forward step-down test (FSDT). Subjective assessment involved the anterior knee pain scale.ResultsWomen with PFP had small to large deficits in maximal strength and RTD of the knee flexors and extensors during isometric, concentric and eccentric contractions (Effect sizes: -0.43 to -1.10; p ≤ 0.016). Small to moderate correlations of maximal concentric and eccentric knee flexor strength and RTD with SLHT and FSDT (r = 0.28 to 0.41; p ≤ 0.037) were identified. Subjective or objective function were not correlated with maximal isometric knee flexor strength and RTD, or any knee extensor measures (p > 0.05).SignificanceMaximal strength and RTD deficits of the knee flexors and extensors were identified in this female PFP cohort, but they were unrelated to subjective function. The relationship of concentric and eccentric knee flexor strength and RTD deficits with poor objective function should be considered in future exercise trials for women with PFP.     

Effect of leg extension training on concentric and eccentric strength of quadriceps femoris muscles

Ten healthy male subjects carried out bilateral concentric leg extension training twice a week for 8 weeks. Before and after the training, maximal voluntary isometric and isokinetic strength and cross-sectional areas of the quadriceps femoris were measured. Maximal bilateral leg extension power increased significantly after the training. Isometric and concentric unilateral strength did not change significantly before and after the training, while eccentric strength at 0.52 and 1.05 rad·s⁻¹ increased after the training with no changes in cross-sectional area. The correlations between strength and cross-sectional area increased significantly after the training. It was speculated that the increase in eccentric strength of knee extensors was due to modification of the neural inhibition during eccentric muscle actions.     

Deficits in eccentric versus concentric torque in children with spastic cerebral palsy

PURPOSE: The purposes of this study were to determine whether ambulatory children with spastic cerebral palsy (CP) had abnormal isokinetic eccentric peak torque values at the knee and ankle, and to gain further insights on the influence of spasticity on voluntary force production in this population. METHODS: Twenty-four children with spastic CP (mean = 11.1+/-2.6 yr) and twenty children of comparable age with no neuromotor pathology (mean = 10.3+/-2.6 yr) participated in an isokinetic testing protocol on a Biodex dynamometer that measured eccentric and concentric peak torques of the knee extensors, knee flexors, ankle dorsiflexors, and ankle plantarflexors. Angular velocity of the eccentric trials was 30 degrees x s(-1) and of the concentric trials was 30 degrees x s(-1), 60 degrees x s(-1), and 120 degrees x s(-1). Peak torque values were normalized by body weight and compared across groups by using ANOVA procedures. Eccentric to concentric (E/C) peak torque ratios at 30 degrees x s(-1) were computed for each muscle and compared across groups. The torque values in CP were also expressed as a percent of the mean normalized value of the comparison group and compared across conditions using repeated measures ANOVA (P < 0.05). RESULTS: Children with CP demonstrated decreased eccentric and concentric peak torques for all muscle groups tested. The relative deficit in eccentric torque was less than the concentric torque and the decrement in concentric torque across speeds was greater in CP for all muscle groups except the ankle dorsiflexors. The E/C ratios for the knee extensors and flexors were also greater in CP. CONCLUSIONS: Children with CP have diminished eccentric as well as concentric peak torques at the knee and ankle. The influence of spasticity on voluntary force production can be inferred from the bias toward greater eccentric torque and the greater decrement in concentric torque across speeds in children with spastic CP.     

Prospective study of concentric and eccentric leg muscle torques, flexibility, physical conditioning, and variation of injury rates during one season of amateur ice hockey

Twenty-three male ice hockey players in a third division amateur ice hockey team were prospectively studied during the 1987-1988 season. O2 uptake, muscle flexibility, and isokinetic concentric and eccentric leg muscle strength were measured before and after the season. All injuries were recorded by one and the same physician attending all the games: 68 injuries occurred altogether but only six of these led to absence from training or matches. O2 uptake and muscle flexibility were unchanged during the season, but a significant drop of both concentric and eccentric quadriceps and hamstring torques occurred in spite of the fact that the team played two games and trained twice per week during the entire season. No correlation between the fall in muscle strength and the injury rate was found. Although many injuries occur in ice hockey, the majority are minor ones that do not lead to absence from playing.     

Knee flexor strength following anterior cruciate ligament reconstruction with the semitendinosus and gracilis tendons.

Knee flexor strength recovery following anterior cruciate ligament reconstruction with the doubled semitendinosus and gracilis tendons was assessed for up to 12 months post-surgery. Twelve patients were followed up, four at 3 months, five at 6 months and three at 12 months post-surgery. Knee flexor moment was recorded using the Biodex System-3 isokinetic dynamometer. Three sets of five repetitions of reciprocal eccentric/ concentric knee flexion contractions were carried out with each set at 1.05, 2.09 or 3.14 rad x s(-1). T-tests were used to test for significant differences between and within groups. The uninjured leg produced greater average peak moments than the injured leg; significant differences (p < 0.05) were seen between the legs at 1.05 rad x s(-1) for the 3-month group concentrically, and all three groups eccentrically. There was no significant difference (p > 0.05) between groups for the percentage deficit between legs. On average, a 23% deficit in average peak moment was still evident at 12 months both eccentrically and concentrically at 1.05 rad x s(-1). Taken as a whole this evidence suggests that there is a deficit in knee flexor strength up to at least 12 months post-surgery following doubled semitendinosus and gracilis tendon graft reconstruction even after a full rehabilitation protocol.     

A pilot study of the eccentric decline squat in the management of painful chronic patellar tendinopathy

Objectives: This non-randomised pilot study investigated the effect of eccentric quadriceps training on 17 patients (22 tendons) with painful chronic patellar tendinopathy.

Methods: Two different eccentric exercise regimens were used by subjects with a long duration of pain with activity (more than six months). (a) Nine consecutive patients (10 tendons; eight men, one woman; mean age 22 years) performed eccentric exercise with the ankle joint in a standard (foot flat) position. (b) Eight patients (12 tendons; five men, three women; mean age 28 years) performed eccentric training standing on a 25° decline board, designed to increase load on the knee extensor mechanism. The eccentric training was performed twice daily, with three sets of 15 repetitions, for 12 weeks. Primary outcome measures were (a) 100 mm visual analogue scale (VAS), where the subject recorded the amount of pain during activity, and (b) return to previous activity. Follow up was at 12 weeks, with a further limited follow up at 15 months.

Results: Good clinical results were obtained in the group who trained on the decline board, with six patients (nine tendons) returning to sport and showing a significantly reduced amount of pain over the 12 week period. Mean VAS scores fell from 74.2 to 28.5 (p = 0.004). At 15 months, four patients (five tendons) reported satisfactory results (mean VAS 26.2). In the standard squat group the results were poor, with only one athlete returning to previous activity. Mean VAS scores in this group were 79.0 at baseline and 72.3 at 12 weeks (p = 0.144).

Conclusion: In a small group of patients with patellar tendinopathy, eccentric squats on a decline board produced encouraging results in terms of pain reduction and return to function in the short term. Eccentric exercise using standard single leg squats in a similar sized group appeared to be a less effective form of rehabilitation in reducing pain and returning subjects to previous levels of activity.