Isokinetic Measurements Research Articles

Isokinetic Plantar Flexion Endurance. Reliability and Validity of output/excitation Measurements

The reliability and validity of isokinetic measurement of plantar flexion endurance has been studied by a method previously described by us which utilizes simultaneous measurements of mechanical contractional work (CW) and integrated electromyogram (iEMG). The reliability was gauged by test/re-test with a two year's interval; while validity was assessed by myoelectric power spectrum analyses. The output/input balance (CW/iEMG) remained unchanged for the group as well as inter-individually. Changes in myoelectric power spectrum as function of number of contractions were clearly indicative of fatigue. Under the present conditions fatigue of fast twitch motor units may explain the rapid decreases in output and excitation followed by nearly steady state levels of all registered parameters. As is the case for non-fatigued isokinetic plantar flexions, the motor unit recruitment order appears quite stereotyped during plantar flexion fatigue. The findings of significantly lower mean power spectrum during the first part of each contraction than during the second part may support the size-principle described by Henneman.

Measurement of torque of trunk flexors at different velocities

The purpose of this study was to determine the test-retest reliability of recording isometric and isokinetic torque of the trunk flexors and to examine the effect of velocity on the torque curves. Thirty healthy subjects were tested on two occasions for isometric torque of trunk flexion at four angles and eccentric and concentric torque at three velocities. Two subjects repeated these tests in the passive mode to determine the torque produced by the trunk when there was no active flexion effort. Intraclass correlation coefficients were above 0.85 for all isometric and isokinetic measures. Standard errors of measurement ranged from 6.9 to 19.5 Nm. Student t-tests indicated no significant differences between occasions for all outcome measures. Examination of passive and active torque curves indicated that the torque produced by the mass of the trunk increased with increasing velocity. It is concluded that both isometric and isokinetic testing of the trunk flexors are reliable, but that testing at higher velocities may not provide a valid measure of muscle performance.

Reproducibility of isokinetic muscle strength measurements in normal and arthritic individuals

The serial reproducibility of an individual's isokinetic torque was assessed in order to establish a reliable baseline value for future comparison. Thirty-two controls and twenty arthritic patients were tested for their peak isokinetic torque on knee flexion and extension and hip flexion at three velocities on five occasions, at fortnightly intervals. The first test was found to provide a reliable baseline for controls and subjects who could generate a peak torque of 54 Newton meters (Nm) or more. The second test was found to be more representative of the series for groups containing weaker subjects. Variation related to torque: for subjects who generate a peak torque of 54 Nm or more, a range of +/- 20% accommodates the variability of 95% of tests. We conclude that a +/- 20% range applied to either the first or second test, depending on the nature of the group to be studied, serves as a representative baseline value.

The effect of combined cryotherapy/compression versus cryotherapy following ACL reconstruction with regard to return-to-sports 3 months after surgery

Aims and Objectives:Morbidity following ACL reconstruction may be a key factor to reduce muscular dysfunction and increase physical activity. While intra-operative factors have been the focus of standardization within the last years, strategies reducing the morbidity such as postoperative cryotherapy have been investigated less. Goal of this study was to compare subjective and objective patient outcomes following ACL reconstruction with combined compression and cryotherapy compared with traditional ice therapy alone. We hypothesized that ryotherapy/compression will show significantly better results three months after ACL reconstruction compared to cryotherapy alone.Materials and Methods:A total of 40 Patients undergoing ACL reconstruction are prospectively randomized to be treated with cryotherapy/compression device (GameReady, CA/USA, group 1) or a cryotherapy device (Aircast Cryocuff, DJO CA/USA, group 2). ACL reconstructions were performed by a single surgeon with semitendinosus graft and standardized rehabilitation protocol. Patients were instructed to use the ice therapy devices 4 times per day for 30min. Pain management directly postoperatively was analyzed as recorded during clinical records and VAS. Follow-up was performed at 12 weeks postoperatively using visual analog scale (VAS), Lysholm knee score, Short Form 36 (SF36), and Tegner acitiy score. Additionally, a functional “return-to-sports” analysis including isokinetic strength measurements (BTE-primus), proprioceptive tests (MTF tests) and a 3d-motion analysis (myomotion, Noraxon) during bilateral drop jumps and single leg hop tests was performed.Results:VAS and comparison of the administrated painkillers showed no significant differences between the two groups. Both groups used the cryotherapy/compression device and the cryotherapy device as determined by the study protocol. At 12 weeks, there was no significant difference between the two groups with regard to Lysholm score, Tegner score, and SF-36, however there was a trend towards better scores in group 1. The was a higher range of motion in group 1 compared to group 2. Functional analysis with isokinetic strength measurements, proprioceptive test and a 3d-motion analysis revealed better functional results in patients of the group cryotherapy/compression device compared to cryotherapy alone.Conclusion:This prospective analysis of 40 patients following semitendinosus ACL reconstruction with one single surgeon implicates that the use of a cryotherapy/compression device (GameReady) showed significantly better objective patient outcomes following ACL reconstruction compared to cryotherapy alone.

Functional outcome in patients following cartilage regenerative treatement: outcome at minimum follow-up of 12 months

Aims and Objectives:Full thickness cartilage defects may be devastating for the patients. Even though, the surgical options have improved, only limited information for returning to sports. Aim of this study was therefore to compare the functional outcome and the return to sports rate of patients following cartilage regenerative treatment at a minimum follow up of 12 months.Materials and Methods:A total of 50 Patients (32 male, 18 female) undergoing cartilage regeneration using a Matrix-associated chondrocyte transplantation (MACT, Novocart, TETEC, Aesculap) (27 femorotibial, 23 patellofemoral) were evaluated at a minimum follow-up of 12 months. Follow-up was performed using a multifactorial functional analysis including isokinetic strength measurements (BTE-primus), proprioceptive tests (MTF tests), a tapping test and a 3d-motion analysis (myomotion, Noraxon) during single leg squats, bilateral drop jumps and single leg hop tests. Agility was assessed using a lateral speedchase (Globalspeed, Hemsbach). Clinical results were recorded using Tegner and Lysholm score.Results:Patients showed a Lysholm score of 86,3 +/-10,3 and 84,0 +/-13,9 for male and female, respectively. The tegner score was significantly reduced when compared to preoperatively (male 4,72 +/-1,6, female 4,75 +/-1,5). Thigh circumference was reduced by an average of 3,6 cm for male and 4,4 cm for female patients. The tapping test revealed no differences between male and female patients providing a leg symmetry index (LSI) of 102,0 (+/-8,4) with an overall average frequency of 10,14 (+/-1,27). During single leg squat male patients had a significantly lower knee flexion of 55,8 (+/-8,5) of the postoperative leg compared to the non-injured leg (62,2 +/-8,2) whereas the knee abduction was -6.8 (+/-15,1) and -11,8 -11,82 (+/-16,6) for the postoperatively and non-injured leg, respectively. Evaluating the single leg hop, the LSI of distance values was 90,8 (+/-11,9) and for height values 84,0 (+/-16,0) for the male patients. There was a trend towards reduced ROM with regard to knee flexion of the injured leg to the non-injured. Cutting time during lateral speedchase showed a LSI of 98,29 (+/-13,8) and 99,44 (+/-8,2) for male and female patients, respectively.Conclusion:This prospective analysis of patients following cartilage regeneration implicates that the use of a multifactorial “return-to-sports” analysis 12 months postoperatively provides a good correlation to the clinical outcome and scores. At this FU point, Patients following MACT show knee joint function that is close to normal.

The Relationship between Dynamic Balance Ability and Low Limb Isokinetic Muscle Function of Elite Judo Athletes

OBJECTIVES The purpose of this study is to examine the relationship between lower extremity isokinetic muscle strength and dynamic balance ability of elite judo athletes and improve the efficient dynamic balance ability of athletes.METHODS A total of 26 male and female judo national candidates (13 males and 13 females) were participated. Isokinetic strength and dynamic balance in three consecutive areas of the lower limbs (knee, hip, waist) were measured. Multiple regression analysis step selection method was used to analyze the correlation between isokinetic strength measurement variables and dynamic balance ability. In addition, the results were analyzed by dividing the difference of fitness variables between male and female athletes and male and female athlete groups.RESULTS The male athlete group showed higher muscle strength in all areas of isokinetic strength (p <.01). Stability was statistically significantly higher (p <.05). There was interrelationship between the lower extremity isokinetic strength and the dynamic balance of the lower extremities in male and female athletes. The trunk flexion showed the highest correlation with the dynamic balance in the male athletes, and trunk flexion and hip extension in female athletes.CONCLUSIONS The trunk muscle strength showed the highest correlation with the dynamic balance ability in male and female athletes.

태권도 시범선수의 플라이오메트릭 트레이닝이 무산소성 파워와 등속성 근기능에 미치는 영향

The purpose of this study was to investigate the effects of plyometric training on the anaerobic power and isokinetic muscular function in Taekwondo demonstration players. Fourteen male Taekwondo demonstrators were randomly divided into plyometric training group (PTG, n=7) and control group (CG, n=7). Exercise program performed for 60 min(warm-up 10 min, main exercise 40 min, cool down 10 min), three times a weeks. The anaerobic power and isokinetic muscular function measurements were performed and pre (0 week), post (8 weeks). Result showed that plyometric training program was significantly increased in anaerobic power (peak power, fatigue index) in post- test than in pre-test. Knee isokinetic muscular function 600/sec, peak torque %Body Weight (extension, flexion) was also significant increased after 8 weeks of plyometric training program. Also, knee isokinetic muscular function 1800/sec total work % Body Weight (extension, flexion) was significant increased post-test than in pre-test. After 8 weeks plyometric training increased anaerobic power and isokinetic muscular function. Thus, suggest that plyometric training can have a positive effect on the performance of taekwondo demonstration players.

No functional differences in anatomic reconstruction with one vs. two suture anchors after non-simultaneous bilateral distal biceps brachii tendon rupture: a case report and review of the literature

BackgroundSurgical reattachment of the tendon is still the gold standard for ruptures of the distal biceps brachii tendon. Several fixation techniques have been described in the literature, with suture anchors being one of the most common fixation techniques. Currently, there is no data available on how many anchors are required for a safe and stable refixation. In this case report clinical data of a patient with non-simultaneous bilateral distal biceps tendon ruptures treated with a different number of suture anchors for each side (one vs. two) are demonstrated.Case presentationA 47-year-old factory worker suffered a rupture of the distal biceps tendon on both arms following two different occasions. The left side was fixed using a single suture anchor, while refixation on the right side was performed with two anchors.The patient was prospectively followed for one year. Functional outcome was assessed using the Andrews Carson Score (ACS), the Oxford Elbow Score (OES), and the Disabilities of Arm, Shoulder and Hand (DASH) Score after six, twelve, 24 and 48 weeks. Furthermore, an isokinetic strength measurement for flexion strength was performed after 24 and 48 weeks.After 48 weeks the patient presented with excellent functional outcome scores and no follow-up complications. During the follow-up period, no differences in the functional scores nor in the isokinetic flexion strength measurement could be detected. Furthermore, no radiological complications (like heterotopic ossifications) could be detected in the postoperative radiographs after one year.ConclusionsAnatomic reattachment of the distal biceps tendon is a successful operative treatment option for distal biceps tendon ruptures. Suture anchor fixation remains one of the most common techniques, as it allows fast surgery and provides good results with respect to range of motion (ROM) and functional scoring according to the current literature. However, the number of anchors required for a stable fixation remains unclear. As indicated by our presented case, we hypothesize, that there are no significant differences between a one-point or a two-point fixation. In the presented case report, no intraindividual differences between the usage of one versus two suture anchors were evident in the short-term follow-up.

Effect of a Core Stabilization Training Program on Performance of Ballet and Modern Dancers

Kalaycioglu, T, Apostolopoulos, NC, Goldere, S, Duger, T, and Baltaci, G. Effect of a core stabilization training program on performance of ballet and modern dancers. J Strength Cond Res 34(4): 1166-1175, 2020-The aim of this study was to investigate the effects of a core stabilization training (CST) program on performance of university-level ballet and modern dancers. Twenty-four dancers between the ages of 18 and 24 years participated in the study. Core stabilization training was performed for 45-60 minutes per day, 3 days a week, for 8 weeks. For 2 days, the training was conducted by an experienced physiotherapist, and the other day, each participant exercised on his or her own. Evaluation of physical fitness parameters included vertical jump performance, flexibility, dynamic balance, coordination, proprioception, muscle, and hip flexion isokinetic strength measures. Wilcoxon signed rank test was used to compare pre- and post-test values. Statistically significant increases in vertical jump performance, dynamic balance, proprioception, and coordination parameters between pre- and post-training (p < 0.05) were observed. After the CST program, peak torque values for the hip flexor muscle isokinetic test of the dancers decreased (p < 0.05). Therefore, the results suggest that the CST program might be used to improve several physical fitness parameters such as jumping, proprioception, coordination, and dynamic balance. Such improvements will aid in the development of artistic skills for university modern dancers.

ISOKINETIC PERFORMANCE AND LIMB ASYMMETRY DIFFERENCES BETWEEN ADOLESCENT MALES AND FEMALES FOLLOWING QUADRICEPS TENDON – PATELLAR BONE AUTOGRAFT ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Background:Accurate measurement of limb strength asymmetry differences between sexes may be important to consider when determining readiness to return to sport among adolescents following ACL reconstruction.Hypothesis/Purpose:The purpose was to compare isokinetic performance between females and males after ACL reconstruction but before return to sport clearance on isokinetic measures of limb strength asymmetry and flexor/extensor strength ratio. We hypothesized there would be no difference in limb strength asymmetry or flexor/extensor strength ratio between sexes measured by isokinetic testing.Methods:We retrospectively collected demographic, surgical, and injury information on patients aged 10 – 18 years at time of surgery. Patients completed isokinetic testing within 5-10 months after primary quadriceps tendon ACL reconstruction, and before return to sport clearance. Isokinetic testing assessed maximum torque at three speeds, 60, 180, and 300 degrees per second, through a limited range of knee extension and flexion. Maximum torque percent deficit of the involved leg compared to the uninvolved leg and flexor/extensor strength ratios were calculated. We compared peak torque extensor deficits and flexor deficits (the % difference between operative and non-operative sides) and flexor/extensor ratios at the three isokinetic test speeds within sexes and between sexes.Results:80 subjects were tested during the study period, of which 44 subjects met inclusion criteria (female: n=29, 66%). Injury characteristics and time since surgery were similar between sexes (Table 1). Greater extensor deficits among males and females were observed at 60 degrees/s compared to 180 degree/s (p=0.003) and 300 degree/s (p<0.001), and at 180 degrees/s compared to 300 degrees/s (p=0.001) (Figure 1). Females demonstrated significantly greater peak torque flexor deficits at 300 degrees/s, compared to males (p=0.04, Figure 2). Within males, greater flexor deficits were observed at 60 degrees/s compared to 180 degrees/s (p<0.001) and 300 degrees/s (p=0.001) (Figure 2). Within females, greater flexor deficits were observed at 60 degrees/s compared to 180 degrees/s (p=0.02, Figure 2). There were no significant interactions or main effects of sex or speed for either the operative or the non-operative limb peak torque flexor/extensor ratio.Conclusion:The results demonstrate greater peak torque flexor deficits among females compared to males at the fastest testing speed in our protocol. Currently, our results indicate variability both within and between sex isokinetic performance at different speeds and suggest that isokinetic testing at slower speeds may be most effective in determining strength deficits between limbs.Tables and Figures:Table 1.Participant characteristics, compared between sexes. Continuous variables are presented as means ± sd, categorical variables are presented as n (%) included in the group. Variable Females (n=29) Males (n=15) P value Age (years)15.7 (1.5)16.3 (1.4)0.20Height (cm)162.4 (9.3)172.1 (8.1)0.002Mass (kg)61.0 (2.1)75.3 (22.1)0.007BMI (kg/m2)23.1 (4.0)25.1 (5.8)0.19Right side injury16 (55%)8 (53%)1.00Concomitant meniscus injury15 (52%)10 (67%)0.52Skeletally mature (pre-op X-ray)19 (66%)10 (67%)1.00Right leg dominant28 (97%)14 (93%)1.00Time since surgery (months)7.3 (1.7)7.0 (1.2)0.51Figure 1.Sex by speed comparisons for peak torque extensor deficits. Error bars represent 95% confidence intervals. A main effect of speed indicated that among both groups, greater extensor deficits existed at 60 degrees/s compared to 180 degrees/s (p=0.003) and 300 degrees/s (p< 0.001), and at 180 degrees/s compared to 300 degree/s (p=0.001).Figure 2.Sex by speed comparisons for peak torque flexor deficits. Error bars represent 95% confidence intervals.A significant sex x speed interaction (p=0.048) indicated:*Females demonstrated greater peak torque flexor deficits than males at 300 degree/s (p=0.04).† Males had greater deficits at 60 degrees/s compared to 180 degrees/s (p<0.001) and 300 degrees/s (p=0.001).† Females had greater deficits at 60 degrees/s compared to 180 degrees/s (p=0.02).

Modeling muscle wrapping and mass flow using a mass-variable multibody formulation

Skeletal muscles usually wrap over multiple anatomical features, and their mass moves along the curved muscle paths during human locomotion. However, existing musculoskeletal models simply lump the mass of muscles to the nearby body segments without considering the effect of mass flow, which has been shown to induce non-negligible errors. A mass-variable multibody formulation is proposed here to simultaneously characterize muscle wrapping and mass flow effects. To achieve this goal, a novel cable element of the muscle–tendon unit, which integrates the mass flow feature with a typical Hill-type constitutive relationship, was developed based on an arbitrary Lagrangian–Eulerian description. In addition, sliding joints were used to constrain the elements to move over the underlying bone geometries. After validating the proposed modeling method using two benchmark samples, it was applied to build a large-scale lower limb musculoskeletal model, where knee joint moments were calculated and compared with isokinetic dynamometry measurements of 12 healthy males. The results of the comparison confirm that muscular mass distribution play an important role in the force transmission of muscle wrapping, and the proposed mass-variable formulation provides a better way of predicting and understanding the dynamics of musculoskeletal systems.

Reliability and validity of eccentric strength measurement of the shoulder abductor muscles using a hand-held dynamometer

ObjectivesTo investigate the validity and intrarater and interrater reliability of eccentric strength testing of the shoulder abductors using a hand-held dynamometer (HHD) versus an isokinetic dynamometer. DesignMethodological. SettingResearch laboratory and athletic training room. ParticipantsForty-seven asymptomatic shoulders of 25 participants were tested in 2 sessions by 2 physiotherapists. Main outcome measuresEccentric strength of the shoulder abductors was measured from 120° to 30° scapular plane abduction using the HHD and isokinetic dynamometer. A gyroscope was used to validate the velocity. Spearman’s rank correlation coefficients, intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated. ResultsThe measurement protocol showed excellent intrarater (ICC[3,3] = 0.987, SEM = 2.59 Nm and MDC = 7.18 Nm) and interrater (ICC[3,3] = 0.990, SEM = 2.28 Nm and MDC = 6.32 Nm) reliability. HHD and isokinetic dynamometer measurements were strongly correlated (rho = 0.760, p < .001). Velocities during HDD testing were similar to those of the isokinetic dynamometer (30°/s) (p > .050). ConclusionsEccentric strength testing of the shoulder abductors using an HHD is a valid and reliable method that can be used for research and clinical purposes when an isokinetic dynamometer cannot be used.

Association Between Familial Mediterranean Fever and Cachexia in Females.

Objectives This study aims to investigate the association between familial Mediterranean fever (FMF) and cachexia in females.Patients and methods The study included 32 female FMF patients (median age 27.50 years; range, 18 to 50 years) and 30 female healthy controls (median age 32 years; range, 18 to 50 years). Patients were classified according to Tel-Hashomer criteria. Circumference of arm, waist, and thigh was recorded. Short form 36 (SF-36) and Multidimensional Assessment of Fatigue (MAF) scale were applied. Composition of the body was measured with dual X-ray absorption. Muscle strength was measured with an isokinetic dynamometer, and strength of hand grip was measured from dominant hand with a hand dynamometer. C-reactive protein, erythrocyte sedimentation rate, fibrinogen and serum creatinine kinase (CK) levels were recorded.Results Body mass index was significantly higher in controls. Twelve patients and one control had cachexia. CK level was significantly higher in patients than controls. Mass of muscle without fat was significantly higher in patients than controls. Peak torque values of extension and flexion at the velocity of 60°/second [Newton meter (Nm)], and value of total work during extension at the velocity of 240°/second (Nm) in isokinetic measures were significantly higher in controls. MAF score was significantly higher in patients with cachexia than patients without cachexia where the subscale scores of SF-36, except the vitality score, were significantly lower in patients with cachexia. However, Tel-Hashomer score was significantly higher in patients with cachexia.Conclusion This study pointed at a significant association between cachexia and FMF in females. Muscle endurance was not affected in FMF patients with cachexia; however, decreased muscle strength, impaired quality of life and increased fatigue were observed in these patients.

ISOKINETIC TRUNK STRENGTH, VALIDITY, RELIABILITY, NORMATIVE DATA AND RELATION TO PHYSICAL PERFORMANCE AND LOW BACK PAIN: A REVIEW OF THE LITERATURE

Isokinetic testing of the trunk is ubiquitous in the literature and with training, however, there is a lack of normative data for adolescents and adult athletes. The purpose of the current review is to present and summarize data about isokinetic trunk strength assessment relative to young, adolescent and adult athletes. Testing position variations, reliability values by age groups, utilization of strength measures and normative data by age groups have been discussed. The information presented within this review are of practical importance for assessment of isokinetic trunk strength to appraise the athlete's current strength level and provide suitable conditioning training program. Literature review. NCBI-PubMed, Web of Science, and SPORTDiscus were searched to identify relevant correlation and intervention studies/trials related to isokinetic testing of the trunk. Forty-two studies meeting the inclusion criteria were included in this literature review. The validity of isokinetic trunk measures (i.e. peak torque; flexion/extension ratios) can be affected by a number of factors including whether the individual is tested in seated or standing position, which can alter the muscle length-tension relationship. Reliability is excellent for some strength measures and moderate to high for muscle endurance. Extension and concentric measures tend to have better reliability than flexion and eccentric measures respectively, while females show typically higher reliability scores than men due to the difficulty in controlling men's body position when testing. Normative data for various populations are provided. Muscle assessment methods using an isokinetic dynamometer are considered reliable with high correlations to peak strength values and flexor/extensor ratios over age groups. However, caution should be exercised when interpreting position-specific isokinetic test results that measure trunk flexion (standing vs seated position). Still, there are indications that low-velocity movements are more reliable for measuring trunk strength. In adolescence, boys appear stronger than girls, with higher values for trunk extensors. Trunk flexors and extensors ratios decrease with growth. Data of isokinetic trunk muscle performance seems to be correlated not only to anthropometric parameters but also to sports discipline and training volume. The effects of sport on the muscular strength of the trunk may have both a preventive factor and a possible risk factor for low back pain. There is evidence for an association between high physical workloads and back injury. 5.

The effect of meniscal repair on strength deficits 6\xa0months after ACL reconstruction

IntroductionRuptures of the anterior cruciate ligament (ACL) can be accompanied by meniscal lesions. Generally, the rehabilitation protocols are altered by meniscal repair. Therefore, the aim of this study was to investigate the effect of meniscal repair on the early recovery of thigh muscle strength in ACL reconstruction (ACLR).Materials and methodsWe performed a matched cohort analysis of n = 122 isolated ACLR (CON) compared to n = 61 ACLR with meniscal repair (ACLR + MR). The subgroups of meniscal repair consisted of 30 patients who had undergone medial meniscus repairs (MM), 19 lateral meniscus repairs (LM) and 12 repairs of medial and lateral meniscus (BM). Isokinetic strength measurement was performed pre-operatively and 6 months post-surgery to perform a cross-sectional and a longitudinal analysis. All injuries were unilateral, and the outcome measures were compared to the non-affected contralateral leg.ResultsSix months postoperatively overall there is no significant difference between the groups (extension strength MR 82% vs. CON 85% and flexion strength 86% vs. 88%, resp.). Subgroup analysis showed that medial repairs exhibit a comparable leg symmetry while lateral repairs performed worse with leg symmetry being 76% in extension and 81% in flexion strength. Patients undergoing BM repair performed in between lateral and medial repairs (82% extension, 86% flexion).ConclusionGenerally, meniscal repair in conjunction with ACLR does not significantly alter the recovery of limb symmetry in strength at 6 months postoperatively. Interestingly, medial repairs seem to perform superior to lateral meniscal repair and repair of both menisci. Since the recovery of symmetric strength is a major factor in rehabilitation testing, these results will help to advise surgeons on appropriate rehabilitation protocols and setting realistic goals for the injured athlete.Level of evidenceIII, retrospective cohort study.

Acoustic Myography in Assessment of Isokinetic and Isometric Muscle Strength in a Healthy Danish Population

Isokinetic and isometric force measurements involving a dynamometer setup are widely used in training and in muscle assessment. For further understanding of the method, we investigated the activation of key functional muscles during isokinetic and isometric movements. During force measurements in an isokinetic Biodex System 3 ProTM, acoustic myography (AMG) was applied. Ten healthy subjects (5 men/5 women) in each decade from 20 to 69 years of age participated in the study. Measurements were carried out during extension and flexion of the ankle, knee and elbow joints. Muscle fibre use was measured by efficiency (E-score) and fibre recruitment (temporal (T-score) and spatial (S-score) summation). AMG measurements showed good reproducibility, and the recruitment pattern of muscle fibres did not change with gender or age. Overall, a significantly higher E-score (P < 0.05) was found at the lower angular velocities than at the higher ones, indicating a lower level of muscle efficiency at higher velocities. Muscles used for knee movement exhibited higher scores than muscles associated with the ankle and elbow joints, most likely related to the greater degree of force production at this joint compared to the ankle and elbow. The ability to activate and inactivate muscle fibres during periods of isokinetic activity becomes increasingly more difficult as the velocity increases. When assessing training effects in sports or rehabilitation, AMG in parallel with isokinetic measurements adds important additional information by giving a measure of possible improvements in efficiency and fibre use.

Hamstring Muscle Injury Prediction by Isokinetic Ratios Depends on the Method Used.

Hamstring muscle injury prediction by isokinetic strength ratios is low but could result from the method-depending either on the use of the limbs or of the sportsmen as references. We aimed to establish a predictive model including unilateral and bilateral ratios calculated from the dominant, nondominant, right, and left limb in injured and uninjured professional soccer players. Cohort study. Soccer team of the French Professional Premier League. Ninety-one professional soccer players. Isokinetic muscle strength was prospectively measured at the beginning of 5 consecutive seasons (2009-2014). Several bilateral, conventional, and functional ratios were calculated from isokinetic measurements at different angular speeds (60 and 240 degrees/s in concentric mode and 30 degrees/s in eccentric mode). Thirty-one soccer players had a hamstring injury during the seasons and were compared with 60 uninjured players. Four models were tested to predict the occurrence of hamstring injury from isokinetic ratios calculated in accordance with the dominant, nondominant, right, and left limb. No predictive model was found when ratios were calculated from the dominant or the right limb. Two models of prediction were found when ratios were calculated from the nondominant or the left limb. In these 2 models, only the bilateral concentric hamstring-to-hamstring ratio at 60 degrees/s was predictive. The best prediction was found with the left limb. We identified 2 low predictive models for hamstring muscle injuries depending on the limbs studied. Because of a low prediction, the consensual method used to predict hamstring muscle injury must be defined in future studies.

CORRELATION OF UPPER AND LOWER EXTREMITIES ISOKINETIC STRENGTH IN ELITE MALE

Background and purposeMuscle strength is one of the most physically important parameters during the competition for judokas. Studies have shown that for judokas, strength in especially the knee and shoulder muscles and the strength balance between right and left sides is very important in terms of both staying in balance and doing spe-cific techniques correctly. Our study aims to find out the correlations between isokinetic lower and upper extremity strength in elite judokas and to examine bilateral and contralateral strength ratios. MethodsThis study is designed according to cross-experimental design with randomized repeated measurements. Fifteen male (mean values: age 19.40 ± 1.24 years, height 170.55 ± 9.44 cm, weight 78.47 ± 18.55 kg, and BMI 27.02 ± 5.82 kg/m2) elite judokas between the ages of 18 and 21 participated voluntarily in the study. Knee extension (EX) and flexion (FLX), shoulder internal rotation (IR) and external rotation (ER) isoki-netic strength measurements of the subjects were measured with concentric/concentric (Con/Con) con-tractions at 60o s-1 and 180o s-1 angular velocities. Ipsilateral hamstring/quadriceps (H/Q), internal rotation/external rotation (IR/ER), contralateral Q/Q, H/H, IR/IR, ER/ER ratios were calculated through lower and upper extremity isokinetic strength. Shapiro–Wilk, Levene, paired sample t-test, and Pearson correlation test were used in statistical analyses. ResultsIn terms of the ipsilateral strength ratios on dominant (DS) and nondominant (NDS) in lower and upper extremities, a significant difference was found only at 60° s-1 angular velocity in only the lower extremity on DS (P 0.05). High correlations were found between all other parameters (P > 0.05). ConclusionsIn conclusion, it was found that lateral asymmetric ratios may differ in elite judokas especially at low angu-lar velocities; however, this difference was not at a level to cause the risk of injury, DS and NDS showed similar strength in both lower and upper extremity, and there were high positive correlations between lower and upper extremity strength.

Relationship between Knee Muscle Strength and Fat/Muscle Mass in Elderly Women with Knee Osteoarthritis Based on Dual-Energy X-Ray Absorptiometry.

Purpose: This study aimed to examine the characteristics and correlation of knee muscle strength and body composition (fat and muscle mass) among elderly women aged 60–70 years with knee osteoarthritis. The present study hypothesized that the muscle mass and the peak torques of the knee joints were considerably low in the knee osteoarthritis (KOA) group. Methods: A total of 47 elderly women aged 60–70 years were recruited from Yangpu District in Shanghai and assigned to the knee osteoarthritis (n = 25, KOA) or healthy control group (n = 22, CON). The knee extension/flexion isokinetic strength measurements were conducted on an isokinetic dynamometer at angular velocities of 90°/s. Dual-energy X-ray absorptiometry was used to measure the body composition (fat and muscle mass in the whole body and lower limbs). The independent sample t-test was employed to determine the effects of knee osteoarthritis on each variable, and the Pearson correlation analysis was used to investigate the correlation between the body composition and knee muscle strength. Results: Compared with the CON, the KOA exhibited the following: (1) Lower absolute peak knee extension torque (66.02 ± 10.57 vs. 56.61 ± 14.69 Nm), relative peak knee extension (1.11 ± 0.19 vs. 0.89 ± 0.26 Nm/kg), and flexion torque (0.62 ± 0.15 vs. 0.54 ± 0.16 Nm/kg, p < 0.05); (2) greater relative peak torque ratio of the knee extension and flexion (0.55 ± 0.08 vs. 0.62 ± 0.15, p < 0.05); and (3) lower total body muscle mass percentage (63.24% ± 4.50% vs. 59.36% ± 3.94%), particularly in the lower limbs (19.96% ± 1.51% vs. 18.47% ± 1.49%, p < 0.05). Furthermore, the total body fat mass percentage was negatively associated with the relative peak knee extension and flexion torque regardless of the group (p < 0.05). The total body muscle mass percentage was positively associated with the relative peak knee extension torque in the two groups and the relative peak knee flexion torque in the CON (p < 0.05). Conclusion: For elderly women with knee osteoarthritis, knee muscle strength decreases significantly, especially for the extensor strength. Moreover, compared with fat mass, the index of muscle mass is more sensitive in detecting the decrease in knee joint torque. Therefore, rather than weight loss alone, the quadriceps muscle and the rear-thigh muscles, which maintain the stability of knee joints during rehabilitation training, should be strengthened emphatically to improve muscle mass.

Variability of concentric angle-specific isokinetic torque and impulse assessments of the knee extensors

Objective: Length-tension relationships are widely reported in research, rehabilitation and performance settings; however, several isometric contractions at numerous angles are needed to understand these muscular outputs. Perhaps a more efficient way to determine torque-angle characteristics is via isokinetic dynamometry; however, little is known about the variability of isokinetic measurements besides peak torque and optimal angle. This paper examines the variability of angle-specific isokinetic torque and impulse measures. Approach: Three sessions of concentric (60°·s−1) knee extensions were performed by both limbs of 32 participants. Assessments were repeated on three occasions, separated by 5–8 d. To quantify variability, the standardized typical error of measurement (TEM) was doubled and thresholds of 0.2–0.6 (small), 0.6–1.2 (moderate), 1.2–2.0 (large), 2.0–4.0 (very large) and >4.0 (extremely large) were applied. Additionally, variability was deemed large when the intraclass correlation coefficient (ICC) was <0.67 and coefficient of variation (CV) > 10%; moderate when ICC > 0.67 or CV < 10% (but not both); and small when both ICC > 0.67 and CV < 10%. Main results: Isokinetic torque and angular impulse show small to medium variability (ICC = 0.75–0.96, CV = 6.4%–15.3%, TEM = 0.25–0.53) across all but the longest (100°) and shortest (10°) muscle lengths evaluated. However, moderate to large variability was found for the optimal angle (ICC = 0.58–0.64, CV = 7.3%–8%, TEM = 0.76–0.86), and torque and impulse at the beginning and end of the range of motion (ICC = 0.57–0.85, CV = 11–42.9%, TEM = 0.40–0.89). Intersession variability of isokinetic torque and impulse were small to moderate at medium (90–20°) joint angles. Significance: Researchers and practitioners can examine the muscle torque-angle relationship and activity-specific torque outputs within these ranges, without resorting to more strenuous and time-consuming isometric evaluations.