Knee Muscle Strength Research Articles

Dental Occlusion Influences Knee Muscular Performances in Asymptomatic Females

Some authors claim that occlusal appliances can enhance athletic performance. Therefore, this study investigated the influence of dental occlusion on knee muscle strength performance. Twelve healthy female subjects (mean age, 24.1 ± 3.1 years) without temporomandibular joint dysfunction participated in this study. Isokinetic quadriceps and hamstring strength were assessed in relation to 3 randomized jaw conditions: mouth closed in maximum intercuspidation without splint, mouth closed on a balanced splint which optimized contact over the dental arch, mouth closed on a piece of resin of 1 mm which created an imbalanced occlusion. Tests were performed at 60 and 240°·s in concentric and 30°·s in eccentric exertions. Concentric performances did not show any significant difference between the 3 jaw conditions (p > 0.05). In contrast, in the eccentric trials related to quadriceps performance, significant differences (p ≤ 0.05) were observed between the resin condition and the 2 other modalities (without splint or with a balanced splint). The imbalanced occlusion created by the resin component corresponded to an average decrease of 9% in eccentric peak torque. The eccentric hamstring peak torques also showed a significant difference (p ≤ 0.05) between measurements with splint and with resin (7% decrease when occlusion was imbalanced). In conclusion, among asymptomatic females, artificial imbalanced occlusion induces immediate and significant alteration of knee eccentric muscle performances. Therefore, occlusion examination should be undertaken on a regular and frequent basis for high-level athletes. Moreover, for athletes using mouthguards, muscular performance assessments should be planned with and without the dental protection.

Muscle strength and body composition during the transition phase in patients treated with recombinant GH to final height.

We assessed body composition and muscle strength during the transition phase in 18 growth hormone (GH) deficient males treated with recombinant GH to final height and 18 controls. According to peak-stimulated GH and basal insulin-like growth factor-1 (IGF-1) during the transition phase, patients were subdivided into GH deficient (GHD-TP, n=9) and GH sufficient (GHS-TP, n=9) groups. Assessments included lean and fat body mass and bone mineral density (BMD), all measured by dual-energy X-ray absorptiometry, and dynamic knee muscle strength, assessed by isokinetic dynamometer. Total body and lumbar spine BMD and muscle strength were lower in GHD-TP patients when compared with GHS-TP and controls (all p<0.05), whereas lean and fat body mass were lower in both GHD-TP and GHS-TP patients when compared with controls (p<0.05). These findings suggest that administration of recombinant GH to final height is not sufficient to provide normal body composition and muscle strength in young male patients with GH deficiency.

Elevated C-reactive protein is associated with lower increase in knee muscle strength in patients with knee osteoarthritis: a 2-year follow-up study in the Amsterdam Osteoarthritis (AMS-OA) cohort

IntroductionThe aim of this study was to examine the associations of elevated serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) with change in muscle strength in patients with established knee osteoarthritis (OA), at 2 years.MethodsData from 186 patients with knee OA were gathered at baseline and at 2-year follow-up. CRP (in milligrams per liter) and ESR (in millimeters per hour) were measured in serum from patients’ blood. Strength of quadriceps and hamstrings muscles was assessed by using an isokinetic dynamometer. The association of inflammatory markers with change in knee muscle strength was analyzed by using uni- and multi-variate linear regression models.ResultsPatients with elevated CRP values at both baseline and 2-year follow-up exhibited a lower increase in knee muscle strength for a period of 2 years (β = -0.22; P = 0.01) compared with the group with non-elevated levels at both times of assessment. The association persisted after adjustment for relevant confounders. Elevated ESR values at both times of assessment were not significantly associated with change in knee muscle strength (β = -0.05; P = 0.49).ConclusionsOur results indicate that elevated CRP values are related to a lower gain in muscle strength over time in patients with established knee OA. Although the mechanism to explain this relationship is not fully elucidated, these results suggest inflammation as a relevant factor influencing muscle strength in this group of patients.

Long-term Stretching Program in Older Active Adults Increases Muscle Strength

The purpose of this study was to evaluate the long-term and repeated bout effects of static stretching program in older active adults, and to clarify the effects of flexibility on muscle strength of knee and trunk.

Is there any correlation between functional and clinical tests in anterior cruciate ligament reconstructed knees after three years?

OBJECTIVE: Hop and jump tests are frequently used in clinical situations in patients with anterior cruciate ligament injury and reconstruction. We are not aware of any study that analyses correlation of functional tests with clinical tests after three years of reconstruction. The purpose of this study was to analyze the relationship between functional and clinical tests. METHOD: Twelve male patients with unilateral anterior cruciate ligament reconstruction were assessed. They performed a one-legged hop test and one-legged jump and reach test, to evaluate knee function. Clinical assessments were: (a) instrumental knee laxity measurement, (b) Q angle, (c) knee flexor and (d) extensor muscle strength. To determine the relationship between functional and clinical tests, a correlation analysis was performed by means of the Spearman correlation coefficient. A p value ≤ 0.05 was considered significant. RESULTS: In anterior cruciate ligament reconstructed vs. healthy knees, hop and jump performance correlated well with muscle strength. Knee laxity did not affect hop and jump performance. CONCLUSIONS: The correlation of functional and strength tests in each group showed functional performance was restored and was independent of anterior knee laxity three years after reconstruction when compared with the contralateral healthy knee. The single-legged hop test correlated better with knee muscle strength and could give information about muscle strength three years after reconstruction. Q angle and extensor strength must be considered together when evaluating hop performance.

An Investigation into Reliability of Knee Extension Muscle Strength Measurements, and into the Relationship between Muscle Strength and Means of Independent Mobility in the Ward: Examinations of Patients Who Underwent Femoral Neck Fracture Surgery

[Purpose] The purpose of the present study was to investigate the reliability of isometric knee extension muscle strength measurement of patients who underwent femoral neck fracture surgery, as well as the relationship between independent mobility in the ward and knee muscle strength. [Subjects] The subjects were 75 patients who underwent femoral neck fracture surgery. [Methods] We used a hand-held dynamometer and a belt to measure isometric knee extension muscle strength three times, and used intraclass correlation coefficients (ICCs) to investigate the reliability of the measurements. We used a receiver operating characteristic curve to investigate the cutoff values for independent walking with walking sticks and non-independent mobility. [Results] ICCs (1, 1) were 0.9 or higher. The cutoff value for independent walking with walking sticks was 0.289 kgf/kg on the non-fractured side, 0.193 kgf/kg on the fractured side, and the average of both limbs was 0.238 kgf/kg. [Conclusion] We consider that the test-retest reliability of isometric knee extension muscle strength measurement of patients who have undergone femoral neck fracture surgery is high. We also consider that isometric knee extension muscle strength is useful for investigating means of independent mobility in the ward.

Hip Resurfacing Versus Large-Diameter Head Total Hip Arthroplasty. A Prospective Comparative Cohort Study on Early Functional Outcomes

Objective: There is no consensus whether hip resurfacing arthroplasty (HRA) performs better than a stem-type total hip arthroplasty (THA). Therefore, the aim of this prospective comparative matched-cohort study was to answer the following questions: 1) Do gait parameters differ between HRA and THA patients at 3, 6, and 12 months after surgery? 2) Are there differences in lower extremity muscle strength at the same time points? 3) Does the selfreported outcome using validated instruments improve similarly in both groups? Methods: One experienced senior surgeon implanted either Durom HRA or CLS Spotorno THA in 34 male patients matched for anthropometric characteristics, preoperative scores and comorbidities. Preoperatively and at 3, 6, and 12 months, gait parameters, hip and knee muscle strength, clinical data and standardized outcome scores were assessed and compared between the two groups. Results: No significant group differences were found for all gait and strength variables. Passive range of motion and mean scores for the SF-36, Harris Hip Score and UCLA activity scale improved significantly over time without differences between groups. At 12 months, more HRA than THA patients were reporting groin pain on impingement testing (20% versus 0%; P<0.05). Conclusions: Excellent early outcomes were achieved by both HRA and THA in terms of score values, lower extremity muscle strength and gait parameters. No clinically relevant differences could be observed between HRA and THA patients. Groin pain after HRA remains a concern that warrants future investigation.

Efficacy of a 12-month, monitored home exercise programme compared with normal care commencing 2 months after total knee arthroplasty: A randomized controlled trial

To evaluate the efficacy of a delayed home exercise programme compared with normal care after primary total knee arthroplasty. Single-blind, prospective, randomized, controlled trial. A total of 108 participants (61% females, mean age 69 years [standard deviation 8.7]), were randomized to a home-based exercise group (EG, n = 53) or to a control group (CG, n = 55). Two months post-operatively, the EG received a home exercise programme, while the CG received no additional guidance. The outcome measurements were: pain and disability, measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC); health-related quality of life (HRQoL), measured using the Short Form-36 questionnaire (SF-36); maximal walking speed; isometric knee muscle strength; and the Timed Up and Go (TUG) test. Measurements were made at baseline and at 12 months thereafter. At the 12-month follow-up, maximal walking speed (p < 0.001) and knee flexion strength (p = 0.009) were significantly greater in the EG. Both groups showed similar improvements in all of the WOMAC subscale scores, the SF-36 summary scores and the TUG time. Home-based training was not superior to normal care with regard to pain, disability or HRQoL, but resulted in greater improvement in objectively measured physical performance.

Arthroscopically Assisted Combined Anterior and Posterior Cruciate Ligament Reconstruction with Autologous Hamstring Grafts–Isokinetic Assessment with Control Group

ObjectiveThe aim of the study was to: 1) evaluate the differences in pre-post operative knee functioning, mechanical stability, isokinetic knee muscle strength in simultaneous arthroscopic patients after having undergone an anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) with hamstring tendons reconstruction, 2) compare the results of ACL/PCL patients with the control group.DesignControlled Laboratory Study.Materials and MethodsResults of 11 ACL/PCL patients had been matched with 22 uninjured control participants (CP). Prior to surgery, and minimum 2 years after it, functional assessment (Lysholm and IKDC 2000), mechanical knee joint stability evaluation (Lachman and “drawer” test) and isokinetic tests (bilateral knee muscle examination) had been performed. Different rehabilitation exercises had been used: isometric, passive exercises, exercises increasing the range of motion and proprioception, strength exercises and specific functional exercises.ResultsAfter arthroscopy no significant differences had been found between the injured and uninjured leg in all isokinetic parameters in ACL/PCL patients. However, ACL/PCL patients had still shown significantly lower values of strength in relative isokinetic knee flexors (p = 0.0065) and extensors (p = 0.0171) compared to the CP. There were no differences between groups regarding absolute isokinetic strength and flexors/extensors ratio. There was statistically significant progress in IKDC 2000 (p = 0.0044) and Lysholm (p = 0.0044) scales prior to (44 and 60 points respectively) and after the reconstruction (61 for IKDC 2000 and 94 points for Lysholm).ConclusionsAlthough harvesting tendons of semitendinosus and/or gracilis from the healthy extremity diminishes muscle strength of knee flexors in comparison to the CP, flexor strength had improved. Statistically significant improvement of the knee extensor function may indicate that the recreation of joint mechanical stability is required for restoring normal muscle strength. Without restoring normal muscle function and strength, surgical intervention alone may not be sufficient enough to ensure expected improvement of the articular function.

Knee muscle strength – A challenge to measure

The aims were to assess the reliability of knee extensor and flexor muscle strength measurements using the Strength Measuring Chair (SMC) in children and adults, and to assess agreement between the SMC and an isokinetic dynamometer (ID). 20 healthy children (10/10 boys/girls, 5–13 years) and 23 adults (10/13 men/women, 23–60 years) were included. Muscle strength tests were performed in the SMC and in the ID. The intra-subject reliability was shown to be excellent in both instruments (ICC 0.93–0.99) and an excellent test–retest reliability of measurements in the SMC was found (ICC 0.87–0.93). Agreement between instruments was evaluated with ICC, paired t-test and Bland–Altman 95% limits of agreement plots. In both adults’ and children's groups, disagreements were found between the two instruments, with more in the children's group. The SMC, which has previously shown to be valid and reliable for measuring plantarflexor muscle strength, reliably measured knee muscle strength in healthy children and adults. However, the large disagreement found between the instruments, especially in the children's group, warrants care in standardizing measuring positions for different body size and warrants caution in comparing one's muscle strength measured using different assessment methods.

A Study on Strength and Training Characteristics of Elite Female Skaters

With methods of ISOMED isokinetic muscle testing system and live observation on Olympic preparation and mathematical statistics, this paper tries to measure and analyze the characteristics of elite female speed skaters knee and hip flexor-extensor muscle strength and training content, period and load for the whole year. The main conclusions are as follows: 1. Features of the skaters knee and hip muscle strength are fit in with the sport biomechanical law, and their fast strength and greatest strength are higher than those of female athletes in other national events. In high speed area, the strength of female athletes even achieves the same level of male ones. 2. The equilibrium and coordination of flexor-extensor and same name muscle group have both reached a high level, but they are lower than international recommended values. 3. The training load of strength throughout the year peaks at the whole phases of preparation 1and preparation 2, the early stages of competition 1 and preparation 3. The load of short distance athletes is larger than that of long distance athletes, but the general trend of both is same. 4. National elite female skaters excise more than before in small muscle group, greatest strength in high speed, continuous speed strength and strength endurance. 5. Based on a comparative analysis of the testing results between these skaters and other athletes, the training arrangement can meet the strength requirements of specific training and can also be the reference of training for other athletes.

Muscle strength is only a weak to moderate predictor of gait performance in persons with late effects of polio

To assess muscle strength in the knee extensors, knee flexors and ankle dorsiflexors in persons with late effects of polio, and determine how much muscle strength, gender, age and BMI are related to gait performance. Ninety community-dwelling ambulant persons (47 men and 43 women; mean age 64 years SD 8) with late effects of polio participated. Isokinetic concentric knee extensor and flexor muscle strength was measured at 60°/s and ankle dorsiflexor muscle strength at 30°/s. Gait performance was assessed by the Timed "Up & Go", the Comfortable and Fast Gait Speed tests, and the 6-Minute Walk test. There were significant correlations between knee extensor and flexor muscle strength and gait performance (p < 0.01), and between ankle dorsiflexor muscle strength and gait performance (p < 0.05), for both lower limbs. Muscle strength in the knee extensors and flexors explained 7% to 37% and 9% to 47%, respectively, of the variance in gait performance. Strength in the ankle dorsiflexors explained 4% to 24%, whereas gender, age and BMI contributed at most an additional 9%. Knee muscle strength, and to some extent ankle dorsiflexor muscle strength, are predictors of gait performance in persons with late effects of polio, but the strength of the relationships indicates that other factors are also important.

A Longitudinal Study of Strength and Gait after Arthroscopic Partial Meniscectomy

Individuals after arthroscopic partial meniscectomy (APM) are at increased risk of developing knee osteoarthritis (OA). Knee muscle weakness and a higher external knee adduction moment (KAM) are potential risk factors for knee OA. This exploratory longitudinal study assessed these risk factors at baseline in an APM group (3 months after surgery) and control group, and again 2 yrs later (follow-up). Eighty-two participants with medial APM and 38 healthy controls were assessed at baseline, with 66 (79%) and 23 (61%), respectively, retested at follow-up. Outcome measures included isokinetic knee muscle strength and medial knee joint load inferred through indices of the KAM during normal and fast-pace walking. Knee muscle strength was reduced by 14%-16% in the APM leg compared with controls at baseline (P ≤ 0.006). However, strength increased in the APM leg over the 2 yrs such that there were no differences compared with controls at follow-up. KAM impulse was at least 20% higher for the APM group (both legs) when compared with controls at baseline and remained similarly higher 2 yrs later (P ≤ 0.022). At baseline peak, KAM was 18% higher in the APM leg as compared with controls only during fast-pace walking (P = 0.013). The peak KAM increased over the 2 yrs in the APM leg by 8%-9% (P ≤ 0.032), although there were no differences in change in KAM between the APM leg and controls. This study found that although knee muscle strength improved, dynamic medial joint load increased over the 2 yrs after APM surgery. These findings may aid in developing therapeutic interventions aimed to prevent or delay the onset of knee OA after APM.

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.

The Associations between Pain Sensitivity and Knee Muscle Strength in Healthy Volunteers: A Cross-Sectional Study

Objectives. To investigate associations between muscle strength and pain sensitivity among healthy volunteers and associations between different pain sensitivity measures. Methods. Twenty-eight healthy volunteers (21 females) participated. Pressure pain thresholds (PPTs) were obtained from 1) computer-controlled pressure algometry on the vastus lateralis and deltoid muscles and on the infrapatellar fat pad and 2) computerized cuff pressure algometry applied on the lower leg. Deep-tissue pain sensitivity (intensity and duration) was assessed by hypertonic saline injections into the vastus lateralis, deltoid, and infrapatellar fat pad. Quadriceps and hamstring muscle strength was assessed isometrically at 60-degree knee flexion using a dynamometer. Associations between pain sensitivity and muscle strength were investigated using multiple regressions including age, gender, and body mass index as covariates. Results. Knee extension strength was associated with computer-controlled PPT on the vastus lateralis muscle. Computer-controlled PPTs were significantly correlated between sites (r > 0.72) and with cuff PPT (r > 0.4). Saline induced pain intensity and duration were correlated between sites (r > 0.39) and with all PPTs (r < −0.41). Conclusions. Pressure pain thresholds at the vastus lateralis are positively associated with knee extensor muscle strength. Different pain sensitivity assessment methods are generally correlated. The cuff PPT and evoked infrapatellar pain seem to reflect the general pain sensitivity. This trial is registered with ClinicalTrials.gov: NCT01351558.

The effects of isokinetic knee extensor and flexor strength on dynamic stability as measured by functional reaching

BACKGROUND: Team sport athletes require dynamic stability in unilateral activities for their sports, which necessitates some degree of knee flexion and extension strength. OBJECTIVE: To analyze the possible association of knee extension and flexion strength with dynamic stability, as measured by the Star Excursion Balance Test (SEBT). METHODS: Sixteen male team sport athletes completed the SEBT, which involves a series of unilateral squats with the subject maximally reaching with the other leg in eight directions. Knee muscle strength was measured isokinetically both concentrically (60 ◦ /s, 180 ◦ /s, 240 ◦ /s) and eccentrically (30 ◦ /s). Subjects were divided into better and lesser groups based on mean functional reach distance. A 1-way analysis of variance (p 0.05) determined between-group differences in reach distances and relative torque. RESULTS: Subjects with better dynamic stability generated greater knee extensor torque concentrically at 180 ◦ /s for the right leg, and at all speeds for the left leg. The effects of knee strength were particularly noteworthy for the left leg, as subjects with better dynamic stability reached significantly further across all 8 directions. CONCLUSION: The results indicate that greater knee extensor strength may enhance unilateral dynamic stability in team sport athletes.

P.2.10 A shorter timed walking or running test may be sufficient for testing function in Duchenne muscular dystrophy

Clinical trials involving exon skipping, gene transfer, and small molecule development are currently underway for children with Duchenne muscular dystrophy. These experimental trials typically use timed walking as the primary measure of efficacy due to ease of test administration, ability to quantify distance walked, and a body of literature investigating the reliability and validity of these walking outcomes. However, a test lasting 6-min has inherent difficulties when testing young children in clinical trials. Ambulatory subjects with DMD (5–12years old; mean=9.6±2.1years) completed timed walking tests, strength testing, the North Star Ambulatory Assessment (NSAA), and timed 4 stairs. The 6-min walk test (6MWT) was compared to two shorter ambulatory assessments: 2-min walk test (2MWT), and 100m walk/run test (100m). The 2MWT was completed according to 6MWT guidelines but lasted only 2-min; whereas the 100m allowed subjects to complete two 50-m laps as quickly as possible, including running if able. Maximum voluntary isometric strength of hip and knee muscles was assessed using a hand-held dynamometer. The 2MWT and 100m were highly correlated with 6MWT (<i>r</i>=0.827 and <i>r</i>=−0.827 respectively, <i>p</i>=0.002). The 100m was most highly correlated with lower extremity strength measures and other functional outcomes. A shorter timed walking or running test may be beneficial for use in clinical trials in children with Duchenne muscular dystrophy. The 2MWT or 100m may decrease individual variability seen in the 6MWT due to shorter walking time or a concrete fixed distance. Further research is needed to determine which ambulatory assessments are most valid, reliable, and sensitive to change over time.

Side-Alternating Vibration Training for Balance and Ankle Muscle Strength in Untrained Women

Side-alternating vibration (SAV) may help reduce the risk of falling by improving body balance control. Such training has been promoted as a strength-training intervention because it can increase muscle activation through an augmented excitatory input from the muscle spindles. To determine the effect of SAV training on static balance during 3 postural tasks of increasing difficulty and lower limb strength. Randomized controlled clinical trial. Laboratory. A total of 21 healthy women were divided into training (n = 11; age = 43.35 ± 4.12 years, height = 169 ± 6.60 cm, mass = 68.33 ± 11.90 kg) and control (n = 10; age = 42.31 ± 3.73 years, height = 167 ± 4.32 cm, mass = 66.29 ± 10.74 kg) groups. The training group completed a 9-week program during which participants performed 3 sessions per week of ten 15-second isometric contractions with a 30-second active rest of 3 exercises (half-squat, wide-stance squat, 1-legged half-squat) on an SAV plate (acceleration = 0.91-16.3g). The control group did not participate in any form of exercise over the 9-week period. We evaluated isokinetic and isometric strength of the knee extensors and flexors and ankle plantar flexors, dorsiflexors, and evertors. Static balance was assessed using 3 tasks of increasing difficulty (quiet bipedal stance, tandem stance, 1-legged stance). The electromyographic activity of the vastus lateralis, semitendinosus, medial gastrocnemius, tibialis anterior, and peroneus longus was recorded during postural task performance, baseline and pretraining, immediately posttraining, and 15 days posttraining. After training in the training group, ankle muscle strength improved (P = .03), whereas knee muscle strength remained unaltered (P = .13). Improved ankle-evertor strength was observed at all angular velocities (P = .001). Postural sway decreased in both directions but was greater in the mediolateral (P < .001) than anteroposterior (P = .02) direction. The electromyographic activity of the peroneus longus increased during the sharpened tandem (P = .001) and 1-legged tasks (P = .007). No changes were seen in the control group for any measures. The SAV training could enhance ankle muscle strength and reduce postural sway during static balance performance. The reduction in mediolateral sway could be associated with the greater use of ankle evertors due to their strength improvement.

Slowed muscle force production and sensory organization deficits contribute to altered postural control strategies in children with developmental coordination disorder

This study aimed to (1) compare the postural control strategies, sensory organization of balance control, and lower limb muscle performance of children with and without developmental coordination disorder (DCD) and (2) determine the association between postural control strategies, sensory organization parameters and knee muscle performance indices among children with DCD. Fifty-eight DCD-affected children and 46 typically developing children participated in the study. Postural control strategies and sensory organization were evaluated with the sensory organization test (SOT). Knee muscle strength and time to produce maximum muscle torque (at 180°/s) were assessed using an isokinetic machine. Analysis of variance was used to compare the outcome variables between groups, and multiple regression analysis was used to examine the relationships between postural control strategies, sensory organization parameters, and isokinetic indices in children with DCD. The DCD group had significantly lower strategy scores (SOT conditions 5 and 6), lower visual and vestibular ratios, and took a longer time to reach peak torque in the knee flexor muscles than the control group (p>0.05). After accounting for age, sex, and body mass index, the vestibular ratio explained 35.8% of the variance in the strategy score of SOT condition 5 (p<0.05). Moreover, the visual ratio, vestibular ratio, and time to peak torque of the knee flexors were all significant predictors (p<0.05) of the strategy score during SOT condition 6, accounting for 14, 19.7, and 19.8% of its variance, respectively. The children with DCD demonstrated deficits in postural control strategy, sensory organization and prolonged duration of muscle force development. Slowed knee muscle force production combined with poor visual and vestibular functioning may result in greater use of hip strategy by children with DCD in sensory challenging environments.

다양한 지지면에서의 스쿼트 운동이 무릎관절 근력 및 위치감각 향상에 미치는 영향

Purpose : The purpose of this study was to compare the Effects of Knee Extensor, Flexor Muscle Strength and Joint Position Sense in Squat Exercise on Variety Surface. Method : Subjuects were consisit of 30 male and female who had non disorder knee joint. we had devided 3 group(control group, balance pad group, and togu group) and we measured that knee joint 15°/45°proprioception(position sense) and Peak Torque of knee extensor, flexor muslce at 60°/sec, 180°/sec angular velocity. Result : First, knee joint 15°proprioception(position sense) of balance pad and togu group was significantly different after exercise(p<.05), but only balance pad group was significantly different at knee joint 45°. Second, knee extensor Peak Torque of balance pad and togu group was significantly different at 60°/sec, 180°/sec angular velocity(p<.05). Third, knee flexor Peak Torque of balance pad and togu group was significantly different at 60°/sec, 180°/sec angular velocity(p<.05). Conclusion : Squat exercises on the balance pad and togu were affects knee joint proprioception and muscle strength improvement. These results suggest that squat exercise on the unstable surface is effective for prevention of knee joint injury and functional activity.