Knee Muscle Groups Research Articles

MRI Spinal Cord Reconstruction Provides Insights into Mapping and Migration Following Percutaneous Epidural Stimulation Implantation in Spinal Cord Injury.

Background: Spinal cord epidural stimulation (SCES) has the potential to restore motor functions following spinal cord injury (SCI). Spinal cord mapping is a cornerstone step towards successfully configuring SCES to improve motor function, aiming to restore standing and stepping abilities in individuals with SCI. While some centers have advocated for the use of intraoperative mapping to anatomically target the spinal cord locomotor centers, this is a resource-intensive endeavor and may not be a feasible approach in all centers. Methods: Two participants underwent percutaneous SCES implantation as part of a clinical trial. Each participant underwent a temporary (1-week, two-lead) trial followed by a permanent, two-lead implantation. SCES configurations were matched between temporary and permanent mappings, and motor evoked potential in response to 2 Hz, for a duration of 250-1000 µs and with an amplitude of 1-14 mA, was measured using electromyography. T2 axial MRI images captured prior to implantation were used to retrospectively reconstruct the lumbosacral segments of the spinal cord. The effects of lead migration on mapping were further determined in one of the participants. Results: In both participants, there were recognized discrepancies in the recruitment curves of the motor evoked potentials across different muscle groups between temporary and permanent SCES mappings. These may be explained by retrospective MRI reconstruction of the spinal cord, which indicated that the percutaneous leads did not specifically target the entire L1-S2 segments in both participants. Minor lead migration appeared to have a minimal impact on spinal cord mapping outcomes in one of the participants but did dampen the motor activity of the hip and knee muscle groups. Conclusions: Temporary mapping coupled with MRI reconstruction has the potential to be considered as guidance for permanent implantation considering target activation of the spinal cord locomotor centers. Since lead migration may alter the synergistic coordination between different muscle groups and since lead migration of 1-2 contacts is expected and planned for in clinical practice, it can be better guided with proper spinal cord mapping and a diligent SCES lead trial beforehand.

Influência da idade e do sexo na força isométrica do joelho e do quadril de indivíduos jovens e de meia idade praticantes recreacionais de atividades físicas

ABSTRACT Muscle strength is an essential part of the functional assessment of health professionals to select and analyze the effects of clinical interventions. This study aimed to determine the influence of gender and age on isometric strength of hip and knee muscle groups. A total of 127 subjects (50.4% men), aged from 20 to 49 years (stratified into three groups: 20-29 years; 30-39 years; and 40-49 years) participated in this study. A hand-held dynamometer was used to measure isometric normalized torque of the hip abductors, hip external rotators, knee extensors, and knee flexors muscles. Regressions and a two-way analysis of variance were used to identify the influence of age and gender on torque of each muscle group. Age and gender were included in the regression model for all groups. Generally, men aged 20-29 and 30-39 were stronger than age-paired women. For participants aged 40-49, torque was similar for men and women for all muscle groups. There was no difference among age groups for women. Generally, young men were stronger than older men. The association between age and gender in hip and knee strength was proved and liable of subgroup stratification after measurements with a hand-held isometric dynamometer.

CONSEQUÊNCIAS DO TREINAMENTO DE FORÇA NOS MEMBROS INFERIORES SOBRE A CAPACIDADE DE SALTO EM ATLETAS DE ARTES MARCIAIS

ABSTRACT Introduction: Chinese martial art has a wide and deep history, and its routine passes are a particular artistic presentation. In exhibitions, choreography with jumping is highly appreciated. Empirically, it is believed that additional strengthening of the lower limbs may promote better results in the performances, but there are no reports in the scientific literature about such a statement. Objective: Verify the consequences of lower limb strength training on jumping ability in martial arts athletes. Methods: 30 first and second tier athletes from the professional women’s team of the Wushu Sports Management Center and Sports Bureau were selected as volunteers for the experimental research. The experiment lasted for three months. The characteristics of the development and change of strength of each muscle group in the knee joint of the athletes’ lower limb during the experimental training were detailed, and the commonly used means of lower limb strength training were found. Results: In strength training, the best means found were skipping steps and rapidly changing direction. The correlation coefficient between jumping and strength was 0.75. Conclusion: After the experiment, the maximum torque and the average power of the lower limb knee muscle groups of the three experimental groups increased in different ranges, which shows that the strength quality of the knee joint of the athletes increased during the suggested training. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Comparison of knee injury of basketball players with different pro—hop modes in kinematic perspective: time period, factor and intervention

Rapid movement techniques in basketball are prone to acute and chronic injuries to the cruciate ligament and internal knee joint movements. This study analyses the biomechanical changes of the non-axial foot after different pro-hop braking from kinematic and kinetic perspectives, in order to provide input to the teaching, intervention and competitive training of basketball pro-hop in basketball. Kistler force measurement, Vicon Motion 3D motion capture and Biovision EMG were used to describe the kinematic and kinetic parameters such as the angle of the knee joint, joint moment, angle at maximum moment and the co-contraction ratio of the rectus femoris and biceps femoris muscles during the landing phase of the non-axial foot after pro-hop and braking in three different pro-hop patterns of female basketball players. The study found that,(1) The pro-hop followed by the non-axial foot initiation technique in basketball movement is prone to knee cruciate ligament injuries, mostly occurring in the first 20% of the landing phase. (2) The angle of the knee joint during the non-axial foot landing phase, the joint moment, the angle at maximum moment, and the co-contraction ratio of the rectus femoris to the biceps femoris muscle govern the risk of non-axial foot initiation injury at the end of the pro-hop. (3) The mechanical load on the knee joint during the non-axial foot landing phase of the one foot pro-hop. (4) The co-contraction ratios of the rectus femoris and biceps femoris were significantly different between the in situ, one foot and double-leg pro-hop. Conclusions, (1) The first 20% of the non-axial foot activation phase after one foot pro-hop is more likely to lead to cruciate ligament and other knee injuries, significantly different from the in-situ and double-leg pro-hop patterns. (2) The lower co-contraction ratio of the rectus femoris and biceps femoris provides protection, support and activation of many peripheral knee muscle groups, partially reducing energy expenditure and improving the quality of movement completion. (3) The training load, injury severity, and The weight and angle of the non-axial foot in different modes of pro-hop and braking can be adjusted to allow for active rest and dynamic compensation of the knee joint under load and movement.

Reliability and validity of hand-held dynamometry for assessing lower limb muscle strength

BACKGROUND: Hand-held dynamometry (HHD) is used to assess muscle strength in various patient populations, but many variations in protocols exist. OBJECTIVE: First, to systematically develop a protocol of HHD for all lower limb muscle groups and evaluate intra-rater reliability; second, to validate HHD with fixed dynamometry for the knee flexor and extensor muscles. METHODS: Thirty healthy young adults (women: men – 15:15) participated in two testing sessions. HHD of 12 lower limb muscle groups was performed in both sessions, while fixed dynamometry of knee muscle groups was performed only in the second session. RESULTS: The intra-rater reliability of HHD was good for five muscle groups and excellent for seven muscle groups (ICC3, k= 0.80–0.96). The criterion validity of HHD ranged from very good to excellent for the knee flexors (r= 0.77–0.89) and from good to very good for the knee extensors (r= 0.65–0.78). However, peak moment values for the knee extensor muscles were underestimated by 32% (p< 0.001). CONCLUSIONS: The proposed HHD protocol provides reliable and valid measurements of lower limb muscle isometric strength in healthy adults, which may also be used to test patients with mild muscle strength deficits. However, possible underestimation of absolute strength must be considered when interpreting the results of knee extensors or other large muscles.

Assessment Protocols of Knee Muscles Spasticity Using the Isokinetic Dynamometer—A Systematic Review

CONTEXT: Spasticity is an increase in resistance to the passive movement of a joint due to an abnormal increase in muscle tone. Considering the difficulty in assessing spasticity accurately, the isokinetic dynamometer is considered a valid measure for assessment of spasticity in multiple joints. OBJECTIVE: Review of assessment protocols of knee muscles spasticity using the isokinetic dynamometer. DATA SOURCES: Research was performed in the PubMed, SciELO, Academic Search Complete and Scopus databases, in English, French and Portuguese language. Studies were included when spasticity assessment protocols with isokinetic dynamometer for knee muscles were applied. STUDY SELECTION: Eligible studies were the ones assessing spasticity with an isokinetic dynamometer protocol in knee muscle groups and excluded those who failed to meet eligibility criteria. DATA EXTRACTION: Two independent reviewers applied the selection criteria to the retrieved studies to limit the number to the final list. DATA SYNTHESIS: A total of 151 studies were retrieved from the literature search and 8 articles met the inclusion criteria. Included studies assessed spasticity with the resource to the isokinetic dynamometer. All studies applied an assessment protocol using isokinetic dynamometer on knee muscle groups. CONCLUSIONS: The isokinetic dynamometer is a valuable tool in the assessment of spasticity and other conditions of tone change, offering more accurate, reliable data, easily to reproduce and to interpret. The resistance torque values have a high correlation with the Ashworth scale reflecting the clinical condition of the muscular tone.

A 12-month prospective exploratory study of muscle and fat characteristics in individuals with mild-to-moderate hip osteoarthritis

BackgroundReductions in lower extremity muscle strength, size and quality and increased fat content have been reported in advanced hip osteoarthritis (OA). Whether these differences are also evident at earlier stages of the disease and the extent to which they might develop over time is unclear. The main purpose of this 12-month exploratory prospective study was to compare changes in muscle and fat characteristics in individuals with mild-to-moderate hip OA and healthy controls.MethodsFourteen individuals with mild-to-moderate symptomatic and radiographic hip OA (n = 9 unilateral; n = 5 bilateral), and 15 healthy controls similar in age and sex without symptoms or radiographic hip OA were assessed at baseline and at 12-month follow-up. Maximal voluntary isometric strength of the hip and knee muscle groups was assessed using an isokinetic dynamometer. Lower extremity lean and fat mass were assessed using dual-energy x-ray absorptiometry, and thigh muscle and fat areas and thigh muscle density were assessed using peripheral quantitative computed tomography.ResultsKnee extension (p = 0.01), hip extension (p < 0.01), hip flexion (p = 0.03), and hip abduction (p < 0.01) strength, lower extremity lean mass (p < 0.01), thigh muscle area (p = 0.03), and thigh muscle density (p < 0.01) were significantly lower in hip OA compared to controls. Hip extension (p < 0.05), hip flexion (p = 0.03), and hip abduction (p = 0.03) strength significantly declined over the follow-up period in the hip OA group.ConclusionsPre-existing deficits in hip muscle strength in individuals with mild-to-moderate hip OA were accentuated over 12-months, though no changes in symptoms or joint structure were observed. A longer follow-up period is required to establish whether strength deficits drive clinical and structural decline in these patients. Interventions to prevent or slow declines in strength may be relevant in the management of mild-to-moderate hip OA.

The influence of maximum isometric muscle force scaling on estimated muscle forces from musculoskeletal models of children with cerebral palsy

BackgroundMusculoskeletal models do not include patient-specific muscle forces but rely on a scaled generic model, with muscle forces left unscaled in most cases. However, to use musculoskeletal simulations to inform clinical decision-making in children with cerebral palsy (CP), inclusion of subject-specific muscle forces is of utmost importance in order to represent each child's compensation mechanisms introduced through muscle weakness. Research aimThe aims of this study were to (i) evaluate if maximum isometric muscle forces (MIMF) in musculoskeletal models of children with CP can be scaled based on strength measurements obtained with a hand-held-dynamometer (HHD), (ii) evaluate the impact of the HHD based scaling approach and previously published MIMF scaling methods on computed muscle forces during gait, and (iii) compare maximum muscle forces during gait between CP and typically developing (TD) children. MethodsStrength and motion capture data of six CP and motion capture data of six TD children were collected. The HHD measurements to obtain hip, knee and ankle muscle strength were simulated in OpenSim and used to modify MIMF of the 2392-OpenSim model. These muscle forces were compared to the MIMF scaled on the child’s body mass and a scaling approach, which included the body mass and muscle-tendon lengths. OpenSim was used to calculate peak muscle forces during gait. ResultsAnkle muscle strength was insufficient to reproduce joint moments during walking when MIMF were scaled based on HHD. During gait, peak hip and knee extensor muscle forces were higher and peak ankle dorsi-flexor forces were lower in CP compared to TD participants. SignificanceHHD measurements can be used to scale MIMF for the hip and knee muscle groups but underestimate the force capacity of the ankle muscle groups during walking. Muscle-tendon-length and mass based scaling methods affected muscle activations but had little influence on peak muscle forces during gait.

Developmental Changes in Isometric Strength: Longitudinal Study in Adolescent Soccer Players.

This study aimed to examine longitudinal changes in isometric strength of the knee extensors (ImKE) and knee flexors (ImKF) at 30° and 60°. The sample was composed of 67 players aged 11.0-13.9 years at baseline over five years. Stature, body mass, skinfolds, and isometric strength (ImKE30°, ImKF30°, ImKE60° and ImKF60°) were measured. Fat mass and fat-free mass (FFM) were derived from skinfolds. Skeletal age was obtained using TW2 RUS. Multilevel random effects regression analyses extracted developmental polynomial models. An annual increment on chronological age (CA) corresponded to 5.6 N (ImKE30°: ), 2.7 N (ImKF30°: ), 4.6 N (ImKE60°: ) and 1.5 N (ImKF60°). An increment of 1 kg in FFM predicted isometric strength as follows: 1.2 N (ImKE30°), 2.1 N (ImKF30°), 3.1 N (ImKE60°) and 2.0 N (ImKF60°). The following equations were obtained: ImKE30°=5.759×CA+1.163×FFM; ImKF30°=-19.369+2.691×CA+0.693×CA2+2.108×FFM; ImKE60°=4.553×CA+3.134×FFM; and, ImKF60°=-19.669+1.544×CA+2.033×FFM. Although skeletal maturity had a negligible effect on dependent variables, age and body size, based on FFM, were relevant longitudinal predictors. During adolescence, systematic assessment of knee extensors and knee flexors are strongly recommended to prevent impairment of knee muscle groups.

Influence of Isokinetic Knee Muscle Torque at Different Angular Velocities on Standing Posture Stability in Healthy Adults

Abstract Objectives Knee muscle groups contribute to proper and safe static and dynamic standing posture stability. The impact of isokinetic knee muscle torque at various angular velocities on standing posture stability is poorly understood. We investigated the influence of isokinetic knee muscle torque at different angular velocities on standing posture stability. Design Cross-sectional study. Setting King Saud University Campus labs. Method The study population was a convenience sample of 30 healthy volunteer college students with a mean age of 20±2 years. Isokinetic concentric peak torque (PT) of knee extensor (Q) and flexor (H) muscle groups as well as the flexor to extensor (H:Q) ratio at three different angular velocities: (60, 180, and 300°/s) were measured, respectively. The postural stability was also measured in both static and dynamic components. The Pearson correlation coefficient was used to examine the association between the different isokinetic components and postural stability (both static and dynamic). Results The PT of Q and H muscle groups and the H:Q ratio at the 3 different angular velocities were significantly associated with static standing balance with eye open on a firm surface (p&lt;0.033). Moreover, the PT of Q at 60 and 180°/s angular velocities was significantly associated with maximum and endpoint excursion components of dynamic standing balance (p&lt;0.044). Conclusions The PT of both Q and H muscle groups at different angular velocities are associated with maintenance of standing static balance. PT of Q only is significantly associated with control of dynamic standing balance in the lower angular velocities.

Reliability and Validity of the Belt-Stabilized Handheld Dynamometer in Hip- and Knee-Strength Tests.

The belt-stabilized handheld dynamometer (HHD) has been used to assess the strength of knee- and hip-muscle groups. However, few researchers have examined its reliability and validity for assessing the strength of these muscles. To evaluate the intra-examiner reliability of the belt-stabilized HHD and its validity and agreement with the isokinetic dynamometer for assessing the strength of knee- and hip-muscle groups. Cross-sectional study. University laboratory. We evaluated 26 healthy participants (13 men, 13 women; age = 23.5 ± 2.8 years, height = 1.7 ± 0.1 m, mass = 68.6 ± 12.4 kg) in 2 sessions using the belt-stabilized HHD and an isokinetic dynamometer for maximum strength of the hip adductors, abductors, flexors, extensors, internal rotators, and external rotators and the knee flexors and extensors. We used reliability values provided by the intraclass correlation coefficient (2,3), standard error of measurement (SEM and percentage SEM), and minimal detectable change; correlation values comparing the belt-stabilized HHD and the isokinetic instrument using the Pearson correlation coefficient (r); and the mean difference in values comparing the 2 instruments using the Bland-Altman method. The intrarater HHD reliability was excellent for most measurements (range = 0.80-0.96; SEM = 1.3-5.3 kilograms of force or 4.8-18.9 Nm, percentage SEM = 7.0%-22.0%, minimal detectable change = 3.6-18.8 kilograms of force or 13.2-52.4 Nm) and was moderate only for bilateral knee flexion and left hip internal rotation (intraclass correlation coefficient [2,3] = 0.62-0.66 and 0.70, respectively). Correlation with the isokinetic dynamometer was moderate to high (r = 0.60-0.90), but the absolute values did not demonstrate concordance between results using the Bland-Altman method. The belt-stabilized HHD measurements were reliable, and although they did not agree with those from the isokinetic dynamometer, the values were correlated for the hip- and knee-muscle groups.

Visually guided weight-shifting in children with cerebral palsy

Musculoskeletal models do not include patient-specific muscle forces but rely on a scaled generic model, with muscle forces left unscaled in most cases. However, to use musculoskeletal simulations to inform clinical decision-making in children with cerebral palsy (CP), inclusion of subject-specific muscle forces is of utmost importance in order to represent each child's compensation mechanisms introduced through muscle weakness.The aims of this study were to (i) evaluate if maximum isometric muscle forces (MIMF) in musculoskeletal models of children with CP can be scaled based on strength measurements obtained with a hand-held-dynamometer (HHD), (ii) evaluate the impact of the HHD based scaling approach and previously published MIMF scaling methods on computed muscle forces during gait, and (iii) compare maximum muscle forces during gait between CP and typically developing (TD) children.Strength and motion capture data of six CP and motion capture data of six TD children were collected. The HHD measurements to obtain hip, knee and ankle muscle strength were simulated in OpenSim and used to modify MIMF of the 2392-OpenSim model. These muscle forces were compared to the MIMF scaled on the child’s body mass and a scaling approach, which included the body mass and muscle-tendon lengths. OpenSim was used to calculate peak muscle forces during gait.Ankle muscle strength was insufficient to reproduce joint moments during walking when MIMF were scaled based on HHD. During gait, peak hip and knee extensor muscle forces were higher and peak ankle dorsi-flexor forces were lower in CP compared to TD participants.HHD measurements can be used to scale MIMF for the hip and knee muscle groups but underestimate the force capacity of the ankle muscle groups during walking. Muscle-tendon-length and mass based scaling methods affected muscle activations but had little influence on peak muscle forces during gait.

Strength and agility training in adolescents with Down syndrome: A randomized controlled trial

The purpose of this study was to investigate the effects of a proposed strength and agility training program of adolescents with Down syndrome. Ninety-two adolescents were recruited and evenly randomized to two intervention groups (exercise group vs. control group). The mean age for the exercise and the control group was 10.6±3.2 and 11.2±3.5 respectively. The exercise training program consisted of a 5-min treadmill exercise and one 20-min virtual-reality based activity administered three times a week for 6 weeks. Pre- and post-test measures were taken for muscle strength and agility performance. The measured muscle included hip extensor, hip flexor, knee extensor, knee flexors, hip abductors, and ankle plantarflexor. A handheld dynamometer was used to measure the lower extremities muscle strength, and agility performance was assessed by the strength and agility subtests of the Bruininks-Oseretsky Test of Motor Proficiency-Second Edition. The exercise group had significant improvements in agility (p=0.02, d=0.80) and muscle strength of all muscle group (all p's<0.05, d=0.51-0.89) assessed in comparison to the control group after the 6-week intervention. Knee muscle groups including both flexors and extensors had the greatest gains among all the muscles measured. A short-term exercise training program used in this study is capable of improving muscle strength and agility performance of adolescents with DS.

Comparison of Lower Extremity Emg Between the 2-Leg Squat and Modified Single-Leg Squat in Female Athletes

To compare EMG activity of selected hip and knee muscle groups in female athletes performing a modified single-leg squat and the 2-leg squat using the same relative intensity. Eleven Division I female athletes from a variety of sports (soccer, softball, and track) completed the study. EMG measurements were taken as the subjects completed 3 parallel repetitions at 85% of their 3-repetition maximum on each exercise. Mean and mean peak EMG data from the gluteus medius, hamstrings, and quadriceps and the quadriceps:hamstrings EMG ratio were compared between the 2 exercises. Statistically higher mean (P < .01) and mean peak (P < .05) gluteus medius and mean and mean peak (P < .01) hamstring EMG activity occurred during the modified single-leg squat. The 2-leg squat produced higher mean and mean peak (P < .05) quadriceps activity and a higher quadriceps:hamstrings EMG ratio (P < .01). Muscle-recruitment patterns appear to differ between the 2 types of squat exercises when performed at the same relative intensity by female athletes.

Coactivation of knee muscles during isokinetic concentric and eccentric knee extensions and flexions in prepubertal gymnasts

Determining the activation of antagonist muscles around the knee joint in athletic children can provide useful information for the better understanding of the mechanisms responsible for strength production in athletic populations during developmental ages. The purpose of the present study was to examine possible differences on a) concentric and eccentric isokinetic torque scores of knee muscles and b) electromyographic (EMG) activity of antagonist knee muscle groups during isokinetic concentric and eccentric knee extensions and flexions between prepubertal gymnasts and non-athletic children. Ten gymnasts (age: 9.3 ± 0.8 yrs, training age: 3.4 ± 1.1 yrs, mass: 30 ± 3.6 kg, height: 132.1 ± 4.6 cm) and ten non-athletic boys (age: 9.1 ± 0.5 yrs, mass: 28.7 ± 3.4 kg, height: 131.4 ± 3.2 cm) performed maximal concentric and eccentric knee extensions and flexions on an isokinetic dynamometer at 45, 90 and 180 ◦ ·s −1 randomly. The torque output of knee extensors and flexors and surface EMG act ivity of vastus lateralis (VL) and biceps femoris (BF) were recorded. The antagonist IEMG values were expressed as a percentage of IEMG of the same muscle when acting as agonist in the same muscle action and angular velocity. ANOVA designs indicated a significant effect of muscle action on the antagonistic IEMG of VL and BF (higher during concentric efforts). An effect of angular velocity was revealed on the antagonistic activity of BF and VL during concentric efforts for both groups. Additionally, no significant difference on the antagonistic activity of knee muscles was found between the two groups examined. The present results suggest that gymnastic training does not affect either torque production or antagonistic activity of knee muscles in boys aged 8-10 years. However, only a longitudinal study could determine possible differences on torque scores and antagonistic activity of knee muscles in gymnasts of various chr onological and training ages.

Concentric versus combined concentric-eccentric isokinetic training: Effects on functional capacity and symptoms in patients with osteoarthrosis of the knee

Gür H, Çakfın N, Akova B, Okay E, Küçükoğlu S. Concentric versus combined concentric-eccentric isokinetic training: effects on functional capacity and symptoms in patients with osteoarthrosis of the knee. Arch Phys Med Rehabil 2002;83:308-16. Objective: To compare the effects of concentric and coupled concentric-eccentric isokinetic resistance training on functional capacity and symptoms of patients with osteoarthrosis (OA) of both knees. Design: Repeated measures. Setting: A university exercise physiology laboratory. Participants: Twenty-three volunteers, ages 41 to 75 years. Patients were randomly assigned to 3 groups: concentric (CON, n = 9), concentric-eccentric (CON-ECC, n = 8), and nontreatment (NONTX, n = 6). Interventions: The CON group performed 12 concentric contractions of each knee extensor and flexor muscles; the CON-ECC group performed 6 concentric and 6 eccentric contractions of each knee muscle group by using a spectrum of angular velocities ranging from 30°/s to 180°/s with 30°/s intervals, for both sides, 3 days a week for 8 weeks. Main Outcome Measures: Functional capacity (rising from a chair, walking, stair climbing and descending) and pain during rest and activities, peak torque, and cross-sectional area (CSA) of knee muscle groups of subjects were tested before and after training. Results: Both training groups showed marked decreases (P <.001) in pain scores and increases (P <.001) in functional capacity together with increases (P <.05–.01) in peak torque and CSA of knee muscles. However, the NONTX group did not display these marked changes after the 8-week period. The results also indicated that concentric-eccentric training has a greater influence on functional capacity, especially stair climbing and descending, than that of concentric training when compared with NONTX group; however, the improvements in pain measurements were better in the CON group compared with the CON-ECC group after the training. Conclusions: The results suggest that with the isokinetic resistance training used in this study, it is possible to improve functional capacity and decrease pain in patients with OA of the knee. The results also showed that extensive training involving a high number of repetitions and eccentric contractions was safe, effective, and well tolerated for the patients with knee OA. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Age and Gender Effects on Reciprocal Moment Ratios in Knee Muscle Contractions

Fifteen young and 17 older females (29.5 ± 4.6 and 58.2 ± 6.1 years of age) and 14 young and 15 older males (27.2 ± 3.3 and 56.5 ± 5.7 years) volunteered as subjects for this study to investigate age and gender effects on reciprocal moment ratios in knee muscle groups. Subjects completed 4 consecutive maximal contractions of dominant knee extensor and flexor muscles at 60°/s for the concentric (CON) and eccentric (ECC) torque tests and 20 consecutive maximal contractions at 180°/s and 1207s for the CON and ECC torque-work tests, respectively. Subjects also performed 5-s isometric (ISM) contractions at a 60° angle and 07s velocity for knee extensors. The results demonstrated that (a) ECC strength, particularly in males, was less influenced than ISM and CON strength by aging factors, (b) older groups, particularly females, possessed greater capacity for ECC muscle action than CON compared to other groups, and (c) older groups, particularly females, had a lower ratio of CON extensors:ECC flexors and a greater ratio of ECC extensors:CON flexors than young groups.

Eccentric muscle performance of elbow and knee muscle groups in untrained men and women

Maximal voluntary eccentric (ECC) and concentric (CON) capacity of knee and elbow muscle groups was investigated in healthy untrained men (N = 40) and women (N = 50), 21-67 yr of age. Purposes of the study were to describe torque-velocity and ECC-CON relationships, and to compare these relationships among muscle groups and between genders. Average torque was measured at angular velocities of 30 degrees and 120 degrees.s-1 from knee flexor (KF), knee extensor (KE), and elbow flexor (EF) muscle groups unilaterally, using an isokinetic protocol including gravity compensation. Data were analyzed using ANOVA procedures, and a significance level of 0.01 was used for all hypothesis testing. Torque-velocity relationships were similar for each muscle group and gender; i.e., ECC average torque did not change as a function of velocity and CONC torque decreased as angular velocity increased. Women generated greater ECC relative to CONC torque than men in upper and lower extremity muscle groups. Muscle groups differed in ECC relative to CONC capacity in both men and women, with ECC/CONC ratios being greater for KE and EF than KF. In all muscle groups, the magnitude of ECC-CONC differences increased as angular velocity increased. Genders differed in relative strength balance between muscle groups, with men exhibiting greater KF/KE and EF/KF torque ratios than women for both ECC and CONC actions. Results of this study contribute to the body of women.(ABSTRACT TRUNCATED AT 250 WORDS)