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Knee Extension (knee + extension)
Terms modified by Knee Extension Selected AbstractsIn vivo load sharing among the quadriceps componentsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2003Li-Qun Zhang Abstract Knee extension is always performed with coordinated contractions of multiple quadriceps muscle components: however, how the load is shared among them under normal and pathological conditions is unclear. We hypothesized that: the absolute moment generated by each quadriceps component increases with the total knee extension moment; the relative contribution and its dependence on the total knee extension moment are different for different quadriceps components; and the centrally located large vastus intermedius (VI) is favored by the central nervous system at low levels of activation. Electrical stimulation was used to activate each quadriceps component selectively in six human subjects. The relationship between the knee extension moment generated by an individual quadriceps component and the corresponding compound muscular action potential (M -wave) over various contraction levels was established for each quadriceps component. This relationship was used to calibrate the corresponding EMG signal and determine load sharing among quadriceps components during submaximal isometric voluntary knee extension. The VI contributed the most (51.8,39.6%) and vastus medialis the least (9.5,12.2%) to knee extension moment (P < 0.05). As the knee extension moment increased, the relative contribution of the VI decreased (P = 0.017) while the relation contribution of the vastus lateralis and medialis increased (P , 0.012). The absolute moment generated by each quadriceps component always increased with the total knee extension moment (P < 0.002). Our in vivo approach determined subject- and condition-specific load sharing among individual muscles and showed that the central nervous system utilized the centrally located, uniarticular VI in submaximal isometric knee extension. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Increased expression of VEGF following exercise training in patients with heart failureEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2001T. Gustafsson Background and aims During the last decades several angiogenic factors have been characterized but so far it is unknown whether local muscle exercise training increases the expression of these factors in patients with moderate heart failure. Expression of the major putative angiogenic factor vascular endothelial growth factor (VEGF) at the level of messneger RNA (mRNA) and/or protein was therefore studied before and after 8 weeks of training in patient with chronic heart failure. Methods VEGF mRNA and protein concentrations were determined in skeletal muscle biopsies before and after 8 weeks of one-legged knee extension training in patients with chronic heart failure (New York Heart Association II,III). Results Exercise training increased the citrate synthase activity and peripheral exercise capacity by 46% and 36%, respectively, in parallel with a two-fold increase in VEGF at both the mRNA (P = 0·03) and protein (P = 0·02) levels Conclusion The increase in VEGF gene expression in response to exercise training indicates VEGF to be one possible mediator in exercise-induced angiogenesis and may therefore regulate an important and early step in adaptation to increased muscle activity in patient with chronic heart failure. [source] Bone properties and muscle strength of young haemophilia patientsHAEMOPHILIA, Issue 4 2005B. Falk Summary., Purpose:, To evaluate bone properties, muscle strength and the relationship between the two, in young (7.0,17.7 years) haemophilia patients (h) and healthy boys (c). Subjects:, Twenty-seven boys with severe haemophilia and 33 healthy boys, of similar age, body mass, height, (mean ± sd for h and c, respectively: 11.2 ± 3.2 vs. 11.4 ± 2.9 years, 42.6 ± 16.6 vs. 41.6 ± 17.3 kg, 145 ± 18 vs. 146 ± 17 cm) and pubertal stage according to secondary sex characteristics, volunteered for the study. all subjects were physically inactive (as determined by questionnaire). Methods:, Subjects performed isokinetic elbow and knee extension and flexion tests at two angular velocities (biodex system ii dynamometer). Bone properties were evaluated by qualitative ultrasound (sunlight omnisenseTM), at the distal radius and tibial mid-shaft. H subjects received prophylactic factor viii treatment within the 24 h preceding testing. No test was performed in the presence of haemorrhage. Results:, Muscle strength was consistently higher in c compared with h, especially in the lower limbs (e.g. knee extension: 1.80 ± 0.44 vs 1.48 ± 0.53 N·m·kg,1 body mass, respectively, p = 0.01). No differences were observed in tibial or radial speed of sound between groups. Correlations between muscle strength and bone properties were observed only in the lower limbs and only in c (r = 0.37,0.48). Conclusion:, Muscle strength, especially lower limbs' strength, was lower in haemophilia patients compared with a matched, similarly inactive population of healthy boys. Nevertheless, at this age range, this relative weakness is not associated with inferior bone properties. [source] Associations Between Lower Extremity Ischemia, Upper and Lower Extremity Strength, and Functional Impairment with Peripheral Arterial DiseaseJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 4 2008Mary M. McDermott MD OBJECTIVES: To identify associations between lower extremity ischemia and leg strength, leg power, and hand grip in persons with and without lower extremity peripheral arterial disease (PAD). To determine whether poorer strength may mediate poorer lower extremity performance in persons with lower arterial brachial index (ABI) levels. DESIGN: Cross-sectional. SETTING: Academic medical centers. PARTICIPANTS: Four hundred twenty-four persons with PAD and 271 without PAD. MEASUREMENTS: Isometric knee extension and plantarflexion strength and handgrip strength were measured using a computer-linked strength chair. Knee extension power was measured using the Nottingham leg rig. ABI, 6-minute walk, and usual and fastest 4-m walking velocity were measured. Results were adjusted for potential confounders. RESULTS: Lower ABI values were associated with lower plantarflexion strength (P trend=.04) and lower knee extension power (P trend <.001). There were no significant associations between ABI and handgrip or knee extension isometric strength. Significant associations between ABI and measures of lower extremity performance were attenuated after additional adjustment for measures of strength. CONCLUSION: These results are consistent with the hypothesis that lower extremity ischemia impairs strength specifically in distal lower extremity muscles. Associations between lower extremity ischemia and impaired lower extremity strength may mediate associations between lower ABI values and greater functional impairment. [source] Knee kinematics in medial osteoarthritis during in vivo weight-bearing activitiesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 12 2009Satoshi Hamai Abstract Dynamic knee kinematics were analyzed for medial osteoarthritic (OA) knees in three activities, including two types of maximum knee flexion. Continuous x-ray images of kneeling, squatting, and stair climbing motions were taken using a large flat panel detector. CT-derived bone models were used for the model registration-based 3D kinematic measurements. Three-dimensional joint kinematics and contact locations were determined using two methods: bone-fixed coordinate systems and by interrogation of CT-based bone model surfaces. The femur exhibited gradual external rotation with knee flexion for kneeling and squatting activities, and gradual internal rotation with knee extension for stair climbing. From 100° to 120° flexion, contact locations showed a medial pivot pattern similar to normal knees. However, knees with medial OA displayed a femoral internal rotation bias and less posterior translation when compared with normal knees. A classic screw-home movement was not observed in OA knees near extension. Decreased variability with both activities and methods of calculation were demonstrated for all three activities. In conclusion, the weight-bearing kinematics of patients with medial OA differs from normal knees. Pathological changes of the articulating surfaces and the ligaments correspond to observed abnormalities in knee kinematics. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1555,1561, 2009 [source] Using real-time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motionJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2009Christine E. Draper Abstract Abnormal patellofemoral joint motion is a possible cause of patellofemoral pain, and patellar braces are thought to alleviate pain by restoring normal joint kinematics. We evaluated whether females with patellofemoral pain exhibit abnormal patellofemoral joint kinematics during dynamic, weight-bearing knee extension and assessed the effects of knee braces on patellofemoral motion. Real-time magnetic resonance (MR) images of the patellofemoral joints of 36 female volunteers (13 pain-free controls, 23 patellofemoral pain) were acquired during weight-bearing knee extension. Pain subjects were also imaged while wearing a patellar-stabilizing brace and a patellar sleeve. We measured axial-plane kinematics from the images. Females with patellofemoral pain exhibited increased lateral translation of the patella for knee flexion angles between 0°and 50° (p,=,0.03), and increased lateral tilt for knee flexion angles between 0° and 20° (p,=,0.04). The brace and sleeve reduced the lateral translation of the patella; however, the brace reduced lateral displacement more than the sleeve (p,=,0.006). The brace reduced patellar tilt near full extension (p,=,0.001), while the sleeve had no effect on patellar tilt. Our results indicate that some subjects with patellofemoral pain exhibit abnormal weight-bearing joint kinematics and that braces may be effective in reducing patellar maltracking in these subjects. Published by Wiley Periodicals, Inc. J Orthop Res 27: 571,577, 2009 [source] Altered knee kinematics in ACL-deficient non-copers: A comparison using dynamic MRIJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2006Peter J. Barrance Abstract Kinematics measured during a short arc quadriceps knee extension exercise were compared in the knees of functionally unstable ACL-deficient patients, these patients' uninjured knees, and uninjured control subjects' knees. Cine phase contrast dynamic magnetic resonance imaging, in combination with a model-based tracking algorithm developed by the authors, was used to measure tibiofemoral kinematics as the subjects performed the active, supine posture knee extension exercise in the terminal 30 degrees of motion. Two determinants of tibiofemoral motion were measured: anterior/posterior location of the tibia relative to the femur, and axial rotation of the tibia relative to the femur. We hypothesized that more anterior tibial positioning, as well as differences in axial tibial rotation patterns, would be observed in ACL-deficient (ACL-D) knees when compared to uninjured knees. Multifactor ANOVA analyses were used to determine the dependence of the kinematic variables on (i) side (injured vs. uninjured, matched by subject in the control group), (ii) flexion angle measured at five-degree increments, and (iii) subject group (ACL-injured vs. control). Statistically significant anterior translation and external tibial rotation (screw home motion) accompanying knee extension were found. The ACL-D knees of the injured group exhibited significantly more anterior tibial positioning than the uninjured knees of these subjects (average difference over extension range,=,3.4,±,2.8 mm, p,<,0.01 at all angles compared), as well as the matched knees of the control subjects. There was a significant effect of interaction between side and subject group on A/P tibial position. We did not find significant differences in external tibial rotation associated with ACL deficiency. The changes to active joint kinematics documented in this entirely noninvasive study may contribute to cartilage degradation in ACL-D knees, and encourage more extensive investigations using similar methodology in the future. © 2005 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loadsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2004Mary T. Gabriel Abstract The anterior cruciate ligament (ACL) can be anatomically divided into anteromedial (AM) and posterolateral (PL) bundles. Current ACL reconstruction techniques focus primarily on reproducing the AM bundle, but are insufficient in response to rotatory loads. The objective of this study was to determine the distribution of in situ force between the two bundles when the knee is subjected to anterior tibial and rotatory loads. Ten cadaveric knees (50 ± 10 years) were tested using a robotic/universal forcemoment sensor (UFS) testing system. Two external loading conditions were applied: a 134 N anterior tibial load at full knee extension and 15°, 30°, 60°, and 90° of flexion and a combined rotatory load of 10 N m valgus and 5 N m internal tibial torque at 15° and 30° of flexion. The resulting 6 degrees of freedom kinematics of the knee and the in situ forces in the ACL and its two bundles were determined. Under an anterior tibial load, the in situ force in the PL bundle was the highest at full extension (67 ± 30 N) and decreased with increasing flexion. The in situ force in the AM bundle was lower than in the PL bundle at full extension, but increased with increasing flexion, reaching a maximum (90 ± 17 N) at 60° of flexion and then decreasing at 90°. Under a combined rotatory load, the in situ force of the PL bundle was higher at 15° (21 ± 11 N) and lower at 30° of flexion (14 ± 6 N). The in situ force in the AM bundle was similar at 15° and 30° of knee flexion (30 ± 15 vs. 35 ± 16 N, respectively). Comparing these two external loading conditions demonstrated the importance of the PL bundle, especially when the knee is near full extension. These findings provide a better understanding of the function of the two bundles of the ACL and could serve as a basis for future considerations of surgical reconstruction in the replacement of the ACL. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Electromyographic analysis of a modified maneuver for quadriceps femoris muscle setting with co-contraction of the hamstringsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2003Masaaki Nakajima Abstract A ,quadriceps femoris muscle setting" is isometric quadriceps femoris exercise which can be widely used in early knee rehabilitation. However this exercise cannot obtain enough co-contraction of the hamstrings. Isolated quadriceps femoris contraction in knee extension imposes severe strain to anterior cruciate ligament. We succeeded in developing a simple training maneuver that is effective in obtaining co-contraction of the hamstrings,a modified maneuver for the quadriceps femoris muscle setting with the contralateral lower limb raised (MQS). In this study, we analyzed the effect of this maneuver by EMG quantification. Twenty-eight healthy young adult men performed sequential trials consisting of normal quadriceps femoris muscle setting (NQS) and MQS. Electromyographic activity was recorded from surface electrodes on the gluteus maximus, vastus medialis, rectus femoris, vastus lateralis, semitendinosus and biceps femoris (long head), and normalized to values derived from maximal isometric trials. The % maximal voluntary isometric contraction (%MVIC) of the vastus medialis, vastus lateralis and rectus femoris did not vary in the each maneuver. However, the %MVIC of the hamstrings varied significantly in the MQS. This study suggests that effective co-contraction of the hamstrings can be obtained in MQS by adjusting the load to the raised lower limb. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] In vivo load sharing among the quadriceps componentsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2003Li-Qun Zhang Abstract Knee extension is always performed with coordinated contractions of multiple quadriceps muscle components: however, how the load is shared among them under normal and pathological conditions is unclear. We hypothesized that: the absolute moment generated by each quadriceps component increases with the total knee extension moment; the relative contribution and its dependence on the total knee extension moment are different for different quadriceps components; and the centrally located large vastus intermedius (VI) is favored by the central nervous system at low levels of activation. Electrical stimulation was used to activate each quadriceps component selectively in six human subjects. The relationship between the knee extension moment generated by an individual quadriceps component and the corresponding compound muscular action potential (M -wave) over various contraction levels was established for each quadriceps component. This relationship was used to calibrate the corresponding EMG signal and determine load sharing among quadriceps components during submaximal isometric voluntary knee extension. The VI contributed the most (51.8,39.6%) and vastus medialis the least (9.5,12.2%) to knee extension moment (P < 0.05). As the knee extension moment increased, the relative contribution of the VI decreased (P = 0.017) while the relation contribution of the vastus lateralis and medialis increased (P , 0.012). The absolute moment generated by each quadriceps component always increased with the total knee extension moment (P < 0.002). Our in vivo approach determined subject- and condition-specific load sharing among individual muscles and showed that the central nervous system utilized the centrally located, uniarticular VI in submaximal isometric knee extension. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Effect of single and multi-joint lower extremity muscle strength on the functional capacity and ADL/IADL status in Japanese community-dwelling older adultsNURSING & HEALTH SCIENCES, Issue 3 2007Masako Azegami rn Abstract Forty-seven community-dwelling older adults aged >70 years participated in this Japanese cross-sectional study to determine the relationship between the isometric lower extremity muscle strength measured during knee extension (KE) in single-joint and total leg extension (TLE) in multi-joint tasks, physical performance tests, and functional status. The physical performance was determined by KE and TLE muscle strength, walking capacity, and balance performance tests, while the functional status was evaluated by interview using basic activities of daily living (ADL) and instrumental activities of daily living (IADL) tools. The results indicated that the TLE muscle strength was significantly related to all the other performance tests, while the KE muscle strength was not correlated with the balance test. Also, the bilateral TLE muscle strength was significantly associated with IADL status compared with the KE muscle strength. In conclusion, multi-joint muscle strength testing might be superior to single-joint muscle strength testing for the screening of the functional impairments of older adults. [source] Validity and normative data for thirty-second chair stand test in elderly community-dwelling Hong Kong ChineseAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2006D.J. Macfarlane It is important to establish valid field measures of lower body strength in the elderly, and to provide representative normative values that are culturally specific in order to help health professionals in the risk assessment of this group. A sample of 1,038 elderly Hong Kong Chinese undertook a 30-sec chair stand test (30CST), with a subsample of 143 completing isometric measures of maximal hip flexion and knee extension, plus a habitual physical activity questionnaire. The 30CST was significantly, yet only weakly, correlated with the isometric strength measures (r , 0.3,0.4), but accurately discriminated between levels of habitual physical activity and across ages in decades. The normative values generated provide useful data for health screening in this elderly Hong Kong population, but do not compare well with their healthier US counterparts. Am. J. Hum. Biol. 18:418,421, 2006. © 2006 Wiley-Liss, Inc. [source] Reliability of knee joint range of motion and circumference measurements after total knee arthroplasty: does tester experience matter?PHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 3 2010Thomas Linding Jakobsen Abstract Background and Purpose.,Two of the most utilized outcome measures to assess knee joint range of motion (ROM) and intra-articular effusion are goniometry and circumference, respectively. Neither goniometry nor circumference of the knee joint have been examined for both intra-tester and inter-tester in patients with total knee arthroplasty (TKA). The purpose of this study was to determine the intra-tester and inter-tester reliability of active and passive knee joint ROM and circumference in patients with TKA when administered by physiotherapists (testers) with different clinical experience.,Method.,The design was an intra-tester, inter-tester and intra-day reliability study. Nineteen outpatients (10 females) having received a TKA were examined by an inexperienced and an experienced physiotherapist. Following a standardized protocol, active and passive knee joint ROM and circumference measurements were obtained using a universal goniometer and a tape measure, respectively. To establish reliability, intraclass correlation coefficients (ICC2,1) and smallest real difference (SRD) were calculated.,Results.,The knee joint ROM and circumference measurements were generally reliable (ICC > 0.8) within and between physiotherapists (except passive knee extension). Changes in knee joint ROM of more than 6.6° and 10° (except active knee flexion) and knee joint circumference of more than 1.0,cm and 1.63,cm represent a real clinical improvement (SRD) or deterioration for a single individual within and between physiotherapists, respectively. Generally, the experienced tester recorded larger knee joint ROM and lower circumference values than that of the inexperienced tester.,Conclusions.,In clinical practice, we suggest that repeated knee goniometric and circumferential measurements should be recorded by the same physiotherapist in individual patients with TKA. Tester experience appears not to influence the degree of reliability. Copyright © 2009 John Wiley & Sons, Ltd. [source] Quadriceps strength and the risk of cartilage loss and symptom progression in knee osteoarthritisARTHRITIS & RHEUMATISM, Issue 1 2009Shreyasee Amin Objective To determine the effect of quadriceps strength in individuals with knee osteoarthritis (OA) on loss of cartilage at the tibiofemoral and patellofemoral joints (assessed by magnetic resonance imaging [MRI]) and on knee pain and function. Methods We studied 265 subjects (154 men and 111 women, mean ± SD age 67 ± 9 years) who met the American College of Rheumatology criteria for symptomatic knee OA and who were participating in a prospective, 30-month natural history study of knee OA. Quadriceps strength was measured at baseline, isokinetically, during concentric knee extension. MRI of the knee at baseline and at 15 and 30 months was used to assess cartilage loss at the tibiofemoral and patellofemoral joints, with medial and lateral compartments assessed separately. At baseline and at followup visits, knee pain was assessed using a visual analog scale, and physical function was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index. Results There was no association between quadriceps strength and cartilage loss at the tibiofemoral joint. Results were similar in malaligned knees. However, greater quadriceps strength was protective against cartilage loss at the lateral compartment of the patellofemoral joint (for highest versus lowest tertile of strength, odds ratio 0.4 [95% confidence interval 0.2, 0.9]). Those with greater quadriceps strength had less knee pain and better physical function over followup (P < 0.001). Conclusion Greater quadriceps strength had no influence on cartilage loss at the tibiofemoral joint, including in malaligned knees. We report for the first time that greater quadriceps strength protected against cartilage loss at the lateral compartment of the patellofemoral joint, a finding that requires confirmation. Subjects with greater quadriceps strength also had less knee pain and better physical function over followup. [source] Effects of detraining on muscle strength and mass after high or moderate intensity of resistance training in older adultsCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2009Savvas P. Tokmakidis Summary This study examined the effects of a 12 weeks detraining period on muscle strength and mass in older adults who had previously participated in a 12 weeks resistance training programme of high [80% of one repetition maximum (1-RM)] or moderate (60% of 1-RM) intensity. Twenty older adults (60,74 years), separated into a high (HI; n = 10; age: 65 ± 5 years) and a moderate (MI; n = 10; age: 66 ± 4 years) intensity resistance training group, were measured in the 1-RM knee extension and flexion strength, and the midthigh cross sectional areas (CSAs) of quadriceps, hamstrings and total thigh before and after a 12 weeks training period as well as after a 12 weeks detraining period. Maximum knee extension and flexion strength and the CSAs of all muscles decreased significantly (P<0·05) with detraining but remained higher (P<0·05) than pretraining levels for both groups. The HI group had a greater decrement (P<0·05) in maximum strength and the CSA of total thigh compared to the MI group but strength levels and the CSA following detraining were higher (P<0·05) for the HI group. The above data suggest that after a short detraining period of 12 weeks, muscle strength and hypertrophy levels of older adults decrease but remain greater than pretraining irrespective of training intensity. Greater declines in muscle strength are observed following HI training but still muscular strength and muscle mass are retained at a higher level than with MI probably due to the higher gains achieved during the training period. [source] Relationship between muscle oxygenation and electromyography activity during sustained isometric contractionCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2008Eiji Yamada Summary The purpose of this study was to clarify the relationship between electromyography (EMG) spectrum changes and muscle oxygenation measured by near-infrared time-resolved spectroscopy (TRS). Each subject performed sustained isometric knee extension at 50% of the maximal voluntary contraction load for 1 min. Surface EMG and TRS were simultaneously recorded from the right vastus lateralis muscle. Mean power frequency (MPF) of the power spectrum was calculated every 5 s during isometric contraction using fast Fourier transform, and decrease in the slope of MPF for 1 min was calculated using the least squares method. The maximal changes in oxygenated haemoglobin and myoglobin (Oxy Hb/Mb) and in deoxygenated haemoglobin and myoglobin (Deoxy Hb/Mb) from pre-contraction values of 1 min were calculated. There were significant relationships between the decrease in the slope of MPF and the maximal changes in Oxy Hb/Mb and Deoxy Hb/Mb (P < 0·05). These findings suggested that changes in Oxy Hb/Mb and Deoxy Hb/Mb indicate muscle fatigue assessed by EMG. [source] Reliability of knee extension and flexion measurements using the Con-Trex isokinetic dynamometerCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2007Nicola A. Maffiuletti Summary The aim of this study was to evaluate the reliability of isokinetic and isometric assessments of the knee extensor and the flexor muscle function using the Con-Trex isokinetic dynamometer. Thirty healthy subjects (15 males, 15 females) were tested and retested 7 days later for maximal strength (isokinetic peak torque, work, power and angle of peak torque as well as isometric maximal voluntary contraction torque and rate of torque development) and fatigue (per cent loss and linear slope of torque and work across a series of 20 contractions). For both the knee extensor and the flexor muscle groups, all strength data , except angle of peak torque , demonstrated moderate-to-high reliability, with intraclass correlation coefficients (ICC) higher than 0·86. The highest reliability was observed for concentric peak torque of the knee extensor muscles (ICC = 0·99). Test,retest reliability of fatigue variables was moderate for the knee extensor (ICC range 0·84,0·89) and insufficient-to-moderate for the knee flexor muscles (ICC range 0·78,0·81). The more reliable index of muscle fatigue was the linear slope of the decline in work output. These findings establish the reliability of isokinetic and isometric measurements using the Con-Trex machine. [source] Learning effect of isokinetic measurements in healthy subjects, and reliability and comparability of Biodex and Lido dynamometersCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 2 2005H. Lund Summary The aim of this study was to examine the learning effect during a set of isokinetic measurements, to evaluate the reliability of the Biodex System 3 PRO dynamometer, and to compare the Biodex System 3 PRO and the Lido Active dynamometers on both extension and flexion over the elbow and the knee at 60° s,1. Thirteen (nine women, four men) healthy participants were measured five times using the Biodex and once using the Lido dynamometer. The intervals between the first four tests were 20 min, and 1 week between tests 4 and 5. Between Biodex and Lido measurements there was a 20 min time interval. When comparing the first five measurements (Biodex), no systematic effect over time and an excellent reliability were found with respect to elbow and knee flexion and extension. No difference in muscle strength (Nm) between the Biodex and Lido was observed for knee flexion (P = 0·59), knee extension (P = 0·18) and elbow extension (P = 0·63). However, elbow flexion showed a 14·8% (95% CI: 11·2,18·4%; P = 0·0001) higher peak torque on Biodex. In conclusion, no learning effect was observed and the Biodex proved to be a highly reliable isokinetic dynamometer. A difference was observed when comparing Biodex and Lido on elbow flexion, but the difference did not outrange the expected variation found with a typical isokinetic measurement, which is why both sets of equipment seem applicable in clinical practice. [source] Effects of resistance training on cardiovascular responses to lower body negative pressure in the elderlyCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 5 2001Lynn B. Panton The purpose of the present study was to determine whether resistance training alters the cardiovascular responses to submaximal lower body negative pressure (LBNP) in the elderly. Twenty-one subjects were randomized into a control (C: n=10; 70 ± 3 years, mean ± SD) or a resistance training (TR: n=11; 67 ± 7 years) group. Subjects in the TR underwent 12 weeks of training consisting of three sets of 8,12 contractions at ,60,80% of their initial maximal one repetition, three times per week, on 10 different machines. Before (Pre) and after (Post) training, all subjects underwent exposures of LBNP of ,10, ,20 and ,40 Torr and muscle biopsy sampling at the vastus lateralis. TR increased (P,0·05) knee extension (Pre=379 ± 140 N, Post=534 ± 182 N) and chest press (Pre=349 ± 137 N, Post=480 ± 192 N) strength. Neither body weight nor percentage body fat were altered (P,>0·05) by training. Resistance training increased (P,0·05) cross-sectional area in both Type I (4203 ± 1196 to 5248 ± 1728 ,m2) and Type II (3375 ± 1027 to 4286 ± 1892 ,m2) muscle fibres. Forearm blood flow, forearm vascular conductance, mean arterial pressure, and heart-rate responses to LBNP were not altered by the training. These data suggest that the cardiovascular responses of elderly to LBNP are unaffected by 12 weeks of whole-body resistance training despite increases in muscle strength and size. [source] | |||||||||||||