Purpose:The purpose of this study was to examine the reliability and the learning effect of an isokinetic trunk flexion-extension protocol designed to simultaneously assess trunk muscle strength and endurance.In addit...Purpose:The purpose of this study was to examine the reliability and the learning effect of an isokinetic trunk flexion-extension protocol designed to simultaneously assess trunk muscle strength and endurance.In addition,the effect of the participants’sex on the reliability data was examined.Methods:Fifty-seven healthy and physically active young men(n=28)and women(n=29)performed the isokinetic protocol 5 times,separated by a week between each of the first 4 sessions and by a month between the last 2 sessions.The protocol consisted of performing 4 trials of 15 maximum flexion-extension concentric exertions at 120°/s(range of trunk motion=50°).The absolute and relative peak torque and total work were calculated to assess trunk flexion and extension strength.In addition,endurance ratio,modified endurance ratio,fatigue final ratio,recovery ratio,and modified recovery ratio variables were used for the assessment of trunk muscle endurance in both directions.Results:Regarding the absolute reliability,no relevant changes were found between paired-comparison sessions for most strength and endurance variables,except for total work and relative total work variables in the flexion movement in both sexes.In addition,the typical error of the isokinetic variables was lower than 10%in both males and females,and minimum detectable changes ranged from 7%to 20%,with a tendency to be higher in females and in endurance variables.The strength variables showed high-to-excellent intraclass correlation coefficients(ICCs;>0.74);however,for the endurance variables only the endurance ratio and the modified endurance ratio obtained moderate-to-high ICC values(0.57<ICC<0.82).In addition,the analysis of the variance reported no significant differences between consecutive pairs of sessions for most variables in both sexes.Conclusion:Overall,these findings provide clinicians,trainers,and researchers with a 10-min single-session protocol to perform a reliable muscle strength and endurance evaluation of trunk flexor and extensor muscles,all within the same protocol.展开更多
Background: There is no proven relationship between back pain and trunk muscle strength, researches in this field yielded conflicting results: some found significant weakness of trunk muscles in back pain patients com...Background: There is no proven relationship between back pain and trunk muscle strength, researches in this field yielded conflicting results: some found significant weakness of trunk muscles in back pain patients compared with healthy subjects, however many researches did not show any relationship. Objectives: The focus of this study is to assess the trunk muscles strength using isokinetic dynamometer then tries to find a relation between back pain and trunk muscles strength. Materials and Methods: Fifty patients with back pain (BP) and 50 healthy subjects were recruited in this study. The flexors and extensors of the trunk muscles were evaluated by Isokinetic dynamometer and compared with control groups. Results: Patients with acute back pain show a significant reduction of the trunk muscles strengths at 120°/s velocities (p value < 0.05) with reversed flexor/extensor ration in comparison with sound subjects. Such a relationship does not show in subacute or chronic back pain patients. Conclusions: Acute back pain associated with decreased the strength of the trunk flexors and extensors at 120°/s. The trunk muscle reinforcement programs must be considered in-patients with acute back pain.展开更多
BACKGROUND： Lower body strength is considered to be a critical component towards successful exercise performance in football players. The aim of this study was to describe the peak isokinetic torque of the knee in pr...BACKGROUND： Lower body strength is considered to be a critical component towards successful exercise performance in football players. The aim of this study was to describe the peak isokinetic torque of the knee in professional football players of different League divisions in Cyprus and assess bilateral and unilateral asymmetries of strength. METHODS： Four hundred and twenty-nine professional male football players participated in this study （Division 1, n = 245 and Division 2, n = 184）. The isokinetic muscle function of the knee was measured using the Humac Norm Testing and Rehabilitation system （CSMi Medical ＆ Solution, USA）. Measurements were collected at angle speeds of 60 °/sec and 300 °/sec, for 3 and 25- repetitions respectively. RESULTS： At both angle speeds, peak isokinetic torque of the knee joint was significantly higher in the right and left knees of players in Division 1 （D1） compared to those competing in Division 2 （D2）. At both testing speeds, peak flexor torque of the left hamstrings was significantly higher in players participating in Division 1 compared to those competing in Division 2. The right hamstrings yielded similar results, except at 60 °/sec, where no difference was found between the groups. CONCLUSION： This study provides valuable data regarding the forces produced by the lower body of football players participating in D1 and D2 in Cyprus, whilst also disclosing there to be no bilateral imbalances or abnormal H/Q ratios. The results of this study may provide pertinent information that can be used by the coaching staff for training and recruiting purposes.展开更多
Purpose The present study examined the effects of a reciprocal,slow velocity forearm flexion and extension task on fatigue-induced changes in isokinetic torque,agonist and antagonist muscle activation,and coactivation...Purpose The present study examined the effects of a reciprocal,slow velocity forearm flexion and extension task on fatigue-induced changes in isokinetic torque,agonist and antagonist muscle activation,and coactivation ratios at slow and moderate velocities.Methods Nine women(mean±SD:age=21.0±1.7 years;body mass=68.1±8.2 kg;height=167.4±7.2 cm)completed pre-testing for forearm flexion and extension isokinetic peak torque at 60 and 180°/s,a fatiguing task of 50 maximal,recip-rocal,isokinetic muscle actions at 60°/s,and post-testing.The amplitude(AMP)of the electromyographic(EMG)signals from the biceps and triceps were simultaneously recorded.Torque and EMG AMP were normalized to the corresponding values from the pre-testing peak torque movements.Repeated measures ANOVAs and pairwise comparisons were used to identify mean changes in torque,EMG AMP,and coactivation ratios.Results The torque analyses indicated significant decreases from pre-to post-testing for forearm flexion(14.1%±5.0%;P<0.001)and extension(25.4%±12.2%;P<0.001)at 60°.At 180°/s there was a significant decrease,collapsed across the forearm movements(24.7%±11.7%;P<0.001).For EMG AMP and coactivation ratios,there were no changes(P>0.05)from pre-to post-testing for either velocity or movement.Conclusions The torque responses were velocity-specific,with greater fatigability exhibited for forearm extension versus flexion at 60°/s,but no differences at 180°/s.The parallel EMG AMP responses between the agonist and antagonist muscles for both velocities supported the lack of fatigue-induced changes in coactivation ratios.Thus,our results demonstrated that fatigue-induced decreases in torque were not attributable to increases in antagonist activation or coactivation.展开更多
It is of great importance to decode motion dynamics of the human limbs such as the joint angle and torque in order to improve the functionality and provide more intuitive control in human-machine collaborative systems...It is of great importance to decode motion dynamics of the human limbs such as the joint angle and torque in order to improve the functionality and provide more intuitive control in human-machine collaborative systems. In order to achieve feasible prediction,both the surface electromyography(sEMG) and A-mode ultrasound were applied to detect muscle deformation and motor intent.Six abled subjects were recruited to perform five trails elbow isokinetic flexion and extension, and each trail contained five repetitions, with muscle deformation and s EMG signals recorded simultaneously. The experimental datasets were categorized as:the ultrasound-EMG combined datasets, ultrasound-only datasets and EMG-only datasets. The support vector machine(SVM)regression model was developed for both elbow joint angle and torque prediction, based on the above three kinds of datasets. The root-mean-square error(RMSE) and the correlation coefficients(R) were applied to evaluate the prediction accuracy. The results across all the subjects for different datasets indicated that the combined datasets and the ultrasound datasets were superior to the sEMG datasets both on elbow joint angle and torque prediction, and there were no significant differences between the combined datasets and the ultrasound datasets. It turns out that elbow angle and torque can be reconstructed by A-mode ultrasound, and the significant findings pave the way towards the application of musculature-driven human-machine collaborative systems.展开更多
Isokinetic relationships of the series of electrophilic substitution reactions of o-substi- tuted phenylmercurials are studied, and the results show, for the first time, that isokinetic correlation analysis can reveal...Isokinetic relationships of the series of electrophilic substitution reactions of o-substi- tuted phenylmercurials are studied, and the results show, for the first time, that isokinetic correlation analysis can reveal the dominant factor in the system of the reactions. The analysis of SE2 of o-substituted phenylmercuric chlorides indicates that the steric effect of o-substituents is the pre-dominant factor when I2 is used as electrophilic agent, however, the electronic effect of o-substituents would become the predominant factor when HCl is used as the electrophilic agent. In SE1 of o-substituted phenylmercuric chlorides, the results of the analysis display that the predomi-nant factor is the field effects of o-substituents. The determination of predominant factors in those reactions would provide further scientific basis for those reaction mechanisms.展开更多
Purpose To determine the amount of familiarization sessions required by breast cancer survivors to achieve a reliable meas-urement of muscle function assessed using isokinetic dynamometry.Methods Twenty-six breast can...Purpose To determine the amount of familiarization sessions required by breast cancer survivors to achieve a reliable meas-urement of muscle function assessed using isokinetic dynamometry.Methods Twenty-six breast cancer survivors performed three isokinetic knee extension tests separated by,at least,48 h.The isokinetic testing protocol included one warm-up set of 10 submaximal knee extensions at 120°/s,followed by two sets of four maximal knee extensions at 60°/s,with 2-min rest interval between sets.Peak torque(PT),time to peak torque(TPT),angle of peak torque(APT),and average power(AP)of each trial was used for the assessment of testing reliability.Percentage change in the mean,typical error,coefficient of variation and intraclass correlation coefficients(ICC2.1)were calculated to determine test-retest reliability.Results For PT,change in mean was lower between trials 2 and 3 than between trials 1 and 2(4.18% and 13.18%,respec-tively),and ICC was greater between trials 2 and 3 than between trials 1 and 2(0.962 and 0.818,respectively).For TPT and APT,ICC was clinically acceptable only between trials 2 and 3(0.757 and 0.803,respectively).For AP,change in mean was clinically acceptable between trials 2 and 3(9.84%),while ICC met acceptable reliability between both,trials 1 and 2 and,trials 2 and 3(0.756 and 0.891,respectively).Conclusion At least one familiarization session is adequate to achieve reliable measurements of muscle function using isokinetic dynamometry,while avoiding the impact of learning effect of the measurements in breast cancer survivors.展开更多
Purpose Muscle strength and power are important requirements in many sports.The correlation of jumping performance as manifestation of muscle power and squatting one-repetition maximum(1RM)has been shown in several in...Purpose Muscle strength and power are important requirements in many sports.The correlation of jumping performance as manifestation of muscle power and squatting one-repetition maximum(1RM)has been shown in several investigations.Correlations with maximum force in a linear isokinetic leg press are still pending.Since different testing devices produce different relationships and rotational isokinetic measurements show conflicting results,further evidence is needed.Methods We investigated the correlation of isokinetic leg press force at 0.1 m/s and 0.7 m/s with squat 1RM and jumping performance in different vertical jumps.Results The results show medium to strong,significant correlations for isokinetic force at 0.1 m/s with squat-and counter-movement-jump performance,whereas isokinetic force at 0.7 m/s showed strong,significant correlations for both jumping tests.Drop jump performance(dropping heights:20,30,40,and 50 cm,respectively)reveals weak to medium,significant correlations with isokinetic force at 0.1 m/s and weak,significant correlations with isokinetic force at 0.7 m/s.Squat 1RM displays strong relationships to isokinetic force with greater coefficients regarding higher movement speed in the isokinetic condition.Conclusion The maximum strength of the leg extensors displays a basic requirement for vertical jumping with great motion in knee-and hip-joints and should be considered in training programs.For vertical jumps that are mainly generated via ankle motion,maximum strength of knee-and hip-extensors plays an indirect role to guarantee for performance-enhancing mechanisms.Additionally,in strength testing,different manifestations of strength performance should carefully be taken into account.展开更多
Background:For the past 30 years,the hamstring(H)-to-quadriceps(Q)(H:Q)torque ratio has been considered an important index of muscle strength imbalance around the knee joint.The purpose of this systematic review was t...Background:For the past 30 years,the hamstring(H)-to-quadriceps(Q)(H:Q)torque ratio has been considered an important index of muscle strength imbalance around the knee joint.The purpose of this systematic review was to examine the value of H:Q torque ratio as an independent risk factor for hamstring and anterior cruciate ligament(ACL)injuries.Methods:Database searches were performed to identify all relevant articles in PubMed,MEDLINE,Cochrane Library,and Scopus.Prospective studies evaluating the conventional(concentric H:Q),functional(eccentric H:concentric Q),and mixed(eccentric H at 300/s:concentric Q at2400/s)H:Q ratios as risk factors for occurrence of hamstring muscle strain or ACL injury were considered.Risk of bias was assessed using the Quality In Prognosis Studies tool.Results:Eighteen included studies reported 585 hamstrings injuries in 2945 participants,and 5 studies documented 128 ACL injuries in 2772participants.Best evidence synthesis analysis indicated that there is very limited evidence that H:Q strength ratio is an independent risk factor for hamstring and ACL injury,and this was not different between various ratio types.Methodological limitations and limited evidence for ACL injuries and some ratio types might have influenced these results.Conclusion:The H:Q ratio has limited value for the prediction of ACL and hamstring injuries.Monitoring strength imbalances along with other modifiable factors during the entire competitive season may provide a better understanding of the association between H:Q ratio and injury.展开更多
In order to investigate the oxidation kinetics of gas coal at low temperatures, we derived a rate equation of oxygen consumption during low-temperature oxidation of gas coal and deduced an E-c equation, expressing the...In order to investigate the oxidation kinetics of gas coal at low temperatures, we derived a rate equation of oxygen consumption during low-temperature oxidation of gas coal and deduced an E-c equation, expressing the relation between active energy E and oxygen concentration c. The reaction order n and active energy E were calculated with this equation based on experiments of static oxygen consumption tests. In addition, we proved the rationality of the E-c equation using a kinetic compensation effect and obtained the isokinetic temperature Tc. The results show that： 1） the gas coal oxidizes easily with increasing temperature and the oxidation tends to be spontaneous at higher temperatures; 2） the oxygen concentration c affects oxygen consumption very much at lower temperatures but has only a small effect at higher temperatures; 3） the isokinetic temperature Tc was 127 ℃ which has been experimentally validated as the key turning point during low-temperature spontaneous combustion of gas coal.展开更多
Background: Infrared thermographic imaging(IRTG) is a safe and reliable technology used to monitor skin temperature. The main aim of our study was to evaluate the relationship between skin temperature changes and musc...Background: Infrared thermographic imaging(IRTG) is a safe and reliable technology used to monitor skin temperature. The main aim of our study was to evaluate the relationship between skin temperature changes and muscle fatigue in order to answer the main research question if IRTG can be used to monitor muscle fatigue.Methods: This was a case study performed on a 23-year-old trained middle distance runner. After warm-up the subject was exercising on the dynamometer for 7.5 min at 120?/s performing only concentric contractions of quadriceps. At the same time IRTG recording of both(exercising and non-exercising) quadriceps was performed.Results: A correlational analysis that was performed in order to quantify the relationship between power and temperature change over time has shown that there is a significant negative correlation between skin temperature increase and power decrease(r = -0.543, p = 0.036) of exercising quadriceps. In linear regression model the exercising quadriceps power could be predicted from skin temperature. No such relationships were noted for the non-exercising limb that served as a control.Conclusion: We believe that correlation between skin temperature change and muscle power output as described in this case study deserves further analysis on the larger sample including subjects of the different ages, health status, and physical abilities in order to create a new tool for monitoring the muscle fatigue.展开更多
Skeletal muscle stiffness is altered after spinal cord injury(SCI).Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI.The study used magnetic resonance elastog...Skeletal muscle stiffness is altered after spinal cord injury(SCI).Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI.The study used magnetic resonance elastography to assess the changes in stiffness after chronic SCI compared to matched able-bodied controls and determine its association with muscle size,spasticity,and peak torque in persons with SCI.Previous studies examined the association between muscle stiffness and spasticity,however,we are unaware of other studies that examined the effects of muscle composition on stiffness after SCI.Ten participants(one female)with chronic SCI and eight(one female)matched able-bodied controls participated in this cross-sectional study.Magnetic resonance elastography was utilized to monitor stiffness derived from shear waves propagation.Modified Ashworth scale was used to evaluate spasticity scores in a blinded fashion.Peak isometric and isokinetic torques were measured using a biodex dynamometer.Stiffness values were non-significantly lower(12.5%;P=0.3)in the SCI group compared to able-bodied controls.Moreover,stiffness was positively related to vastus lateralis whole muscle cross-sectional area(CSA)(r2=0.64,P<0.005)and vastus lateralis absolute muscle CSA after accounting for intramuscular fat(r2=0.78,P<0.0007).Stiffness was also positively correlated to both isometric(r2=0.55-0.57,P<0.05)and isokinetic peak(r2=0.46-0.48,P<0.05)torques.Our results suggest that larger clinical trial is warranted to confirm the preliminary findings that muscle stiffness is altered after SCI compared to healthy controls.Stiffness appeared to be influenced by infiltration of intramuscular fat and modestly by the spasticity of the paralyzed muscles.The preliminary data indicated that the relationship between muscle stiffness and peak torque is not altered with changing the frequency of pulses or angular velocities.All study procedures were approved by the Institutional Review Board at the Hunter Holmes McGuire VA Medical Center,USA(IRB#:02314)on May 3,2017.展开更多
Purpose:The purpose of this study was to compare the effects of an 8-week whole-body vibration training program in various frequency and amplitude settings under the same acceleration on the strength and power of the ...Purpose:The purpose of this study was to compare the effects of an 8-week whole-body vibration training program in various frequency and amplitude settings under the same acceleration on the strength and power of the knee extensors.Methods:Sixty-four young participants were randomly assigned to 1 of 4 groups with the same acceleration(4 g):high frequency and low amplitude(n = 16,32 Hz,1 mm) group,medium frequency and medium amplitude(n = 16,18 Hz,3 mm) group,low frequency and high amplitude(n = 16,3 Hz,114 mm) group,and control(n = 16,no vibration) group.All participants underwent 8 weeks of training with body mass dynamic squats,3 sessions a week.Results:The results showed that the high frequency and low amplitude group increased significantly in isometric contraction strength and 120°/s isokinetic concentric contraction strength;the medium frequency and medium amplitude group increased significantly in 60°/s and 120°/s isokinetic strength of both concentric and eccentric contraction;and the low frequency and high amplitude group increased significantly in 60°/s and 120°/s isokinetic eccentric contraction strength.Conclusion:All frequency and amplitude settings in the 8-week whole-body vibration training increased muscle strength,but different settings resulted in various neuromuscular adaptations despite the same intensity.展开更多
Background： Various training schemes have sought to improve golf-related athletic ability. In the golf swing motion, the muscle strengths of the core and arms play important roles, where a difference typically exists...Background： Various training schemes have sought to improve golf-related athletic ability. In the golf swing motion, the muscle strengths of the core and arms play important roles, where a difference typically exists in the power of arm muscles between the dominant and non- dominant sides. The purposes of this study were to determine the effects of exercises strengthening the core and non-dominant arm muscles of elite golf players （handicap 〈 3） on the increase in drive distance, and to present a corresponding training scheme aimed at improving golf performance ability. Methods： Sixty elite golfers were randomized into the control group （CG, n = 20）, core exercise group （CEG, n = 20）, and group receiving a combination of muscle strengthening exercises of the non-dominant arm and the core （NCEG, n = 20）. The 3 groups conducted the corresponding exercises for 8 weeks, after which the changes in drive distances and isokinetic strength were measured. Results： Significant differences in the overall improvement of drive distance were observed among the groups （p 〈 0.001）. Enhancement of the drive distance of NCEG was greater than both CG （p 〈 0.001） and CEG （p = 0.001）. Except for trunk flexion, all variables of the measurements of isokinetic strength for NCEG also showed the highest values compared to the other groups. Examination of the correlation between drive distance and isokinetic strength revealed significant correlations of all variables except trunk flexion, wrist extension, and elbow extension. Conclusion： The combination of core and non-dominant arm strength exercises can provide a more effective specialized training program than core alone training for golfers to increase their drive distances.展开更多
This study was designed to investigate the effects of kinesio tape （KT） on functional performance of female basketball players with and without chronic ankle instability （CAI）. The players with （n = 15） and with...This study was designed to investigate the effects of kinesio tape （KT） on functional performance of female basketball players with and without chronic ankle instability （CAI）. The players with （n = 15） and without ankle instability （n = 16） were enrolled. KT was applied with tension in the instability group and without tension in the control group. Before KT application, 30 minutes and 48 hours after application; muscle strength and endurance were tested in plantar flexion and dorsiflexion, joint position sense was measured in ankle dorsiflexion and plantar flexion using a dynamometer. Dynamic postural stability was evaluated with a balance system between the levels of 12-4. Vertical jumping heights were measured by jump-meter. The results were statistically assessed by SPSS 19 version. In CAI group, dynamic postural stability showed statistically significant improvement in both legs overall （P 〈 0.0001）, antero-posterior （P 〈 0.004） and medio-lateral indexes （P 〈 0.009）. CAI group showed significant improvements in one-leg postural stability overall, antero-posterior and medio-lateral indexes after 48 hours （P 〈 0.011, P 〈 0.022, P 〈 0.038, respectively）. Joint position sense, vertical jump height and muscle strength and endurance were also compared in both groups, and there was no significant difference between the groups. Postural stability indexes were decreased by supporting fimction of KT to the ankle. As a result, we can say that KT has a beneficial effect on maintaining posture by correcting standing kinematics in cases with CAl. We may suggest that KT can be utilized in preventing the injuries in CAI.展开更多
An isokinetic sampling probe is designed and constructed to measure entrained liquid droplet fluxes in separated gasliquid pipe flows. This probe also has the capability of working as a non-standard Pitot tube when th...An isokinetic sampling probe is designed and constructed to measure entrained liquid droplet fluxes in separated gasliquid pipe flows. This probe also has the capability of working as a non-standard Pitot tube when the sampling is stopped. CFD simulations using the commercial software Ansys CFX were carried out for single phase gas flow to analyze the non-standard design. Pitot tube velocity calculations and isokinetic sampling conditions were studied. The predicted results were compared against theoretical velocity profiles from the literature and with gas single phase experimental data acquired in a horizontal 49 m long steel pipeline with an internal diameter of 69 mm. The experiments were done by using a dense gas (SF6) at 7 bara. An asymmetry of the experimental velocity profiles reproduced with the numerical simulations. The CFD simulations made it possible to verify the design and predict and correct an installation problem.展开更多
Vitamin C is a popular supplement in exercise and sport for its chemical properties i.e.v antioxidant capabilities. However, no clear role has been established for vitamin C supplementation (VCS) within these areas de...Vitamin C is a popular supplement in exercise and sport for its chemical properties i.e.v antioxidant capabilities. However, no clear role has been established for vitamin C supplementation (VCS) within these areas despite nearly a century’s worth of ongoing research. This study examined peak muscular pushing force (PMF) before and after a VCS intervention, 250 mg every 12 hrs for 28 days, in nine participants whom were naive to VCS and resistance exercise (RE). A dynamometer was used to perform two RE bouts, pre- and post-intervention, that quantified PMF during a state of exercise-induced oxidative stress (EI-OS). Saliva was collected for EIOS analysis from each participant before and after each RE bout;salivary vitamin C (VC) and free salivary malondialdehyde (MDA) were the examined biomarkers. PMF increased significantly post-intervention (405.48 ± 92.75 m·kg·s-2) from baseline (368.31 ± 76.36 m·kg·s-2, p < 0.05). MDA elevated significantly after the pre-intervention RE bout (0.385 ± 0.017 μg/mL) and the post-intervention RE bout (0.373 ± 0.014 μg/mL) compared to the baseline measures (0.373 ± 0.014 μg/mL, 0.359 ± 0.008 μg/mL;p < 0.01);a significant reduction in MDA was observed post-intervention, confirming vitamin C’s ability to reduce oxidative stress (p < 0.05). VC increased post-intervention (1.22 ± 0.73 μg/mL) from baseline (0.47 ± 0.51 μg/mL, p < 0.001). The results from this study suggest VCS is capable of increasing PMF by reducing EIOS in untrained individuals, and can be possibly used for enhancing resistance-exercise performance.展开更多
As a major equipment for thermal power plants,the main function of coarse powder separators is to separate particles into size groups according to particle diameter.With the rising coal prices,power plants are using m...As a major equipment for thermal power plants,the main function of coarse powder separators is to separate particles into size groups according to particle diameter.With the rising coal prices,power plants are using more low-density lignite.Consequently,the original equipment does not operate under normal conditions.Therefore,to return the equipment to normal operating conditions,the isokinetic sampling method,computational fluid dynamics(CFD),and discrete phase model(DPM)based on the Euler-Lagrange method are applied in this research to analyze the effect of baffle shapes,baffle numbers,and centrifugal blades on the equipment performance index,like R90.The shape of the baffle plate was optimized and improved.Preferential method was applied to determine the optimal number of baffles to ensure normal working conditions.Results show that curved baffles can suppress the axial negative gradient field below themselves better than rectangular baffles.The curved baffles selected by the optimal seeking method make full use of the negative axial gradient field and provide the particles entering the separation zone at tangential velocity in advance with the addition of centrifugal blades.Thus,pre-separation can be realized.The R90 is 5 at the separator outlet and 95 at the powder return port,indicating that the output capacity of the separator returned to a reasonable operating performance.展开更多
In order to determine a rational protocol for isotonic training from macroscopic angle, five training protocols were designed, particularly protocols composed of pure eccentric contraction with heavy resistance in dif...In order to determine a rational protocol for isotonic training from macroscopic angle, five training protocols were designed, particularly protocols composed of pure eccentric contraction with heavy resistance in different propotions. The study results indicated that the protocol mixed with faster speed eccentric training,being more rational than traditional isotonic training and pure isotonic eccentric training, had the most all - round effects(including change of musle size, isotonic strength, musle power and et al. ). The protocol principle mixed with faster speed eccentric training may be widely used in rehabilitation and sports training,especially in the sports events of strength resistance. The significance to study the ratio of eccentric contaction to concentic contraction was suggested.展开更多
基金the financial support of Ministerio de Ciencia e Innovación(DEP2010-16493)Generalitat Valenciana(ACOMP/2011/130)+1 种基金Spain.Casto Juan-Recio and Alejandro López-Valenciano were supported by predoctoral grants given by Generalitat Valenciana(Val i+d)(ACOMP/2011/130)Ministerio de Educacion,Cultura y Deporte(FPU)(DEP2010-16493)。
文摘Purpose:The purpose of this study was to examine the reliability and the learning effect of an isokinetic trunk flexion-extension protocol designed to simultaneously assess trunk muscle strength and endurance.In addition,the effect of the participants’sex on the reliability data was examined.Methods:Fifty-seven healthy and physically active young men(n=28)and women(n=29)performed the isokinetic protocol 5 times,separated by a week between each of the first 4 sessions and by a month between the last 2 sessions.The protocol consisted of performing 4 trials of 15 maximum flexion-extension concentric exertions at 120°/s(range of trunk motion=50°).The absolute and relative peak torque and total work were calculated to assess trunk flexion and extension strength.In addition,endurance ratio,modified endurance ratio,fatigue final ratio,recovery ratio,and modified recovery ratio variables were used for the assessment of trunk muscle endurance in both directions.Results:Regarding the absolute reliability,no relevant changes were found between paired-comparison sessions for most strength and endurance variables,except for total work and relative total work variables in the flexion movement in both sexes.In addition,the typical error of the isokinetic variables was lower than 10%in both males and females,and minimum detectable changes ranged from 7%to 20%,with a tendency to be higher in females and in endurance variables.The strength variables showed high-to-excellent intraclass correlation coefficients(ICCs;>0.74);however,for the endurance variables only the endurance ratio and the modified endurance ratio obtained moderate-to-high ICC values(0.57<ICC<0.82).In addition,the analysis of the variance reported no significant differences between consecutive pairs of sessions for most variables in both sexes.Conclusion:Overall,these findings provide clinicians,trainers,and researchers with a 10-min single-session protocol to perform a reliable muscle strength and endurance evaluation of trunk flexor and extensor muscles,all within the same protocol.
文摘Background: There is no proven relationship between back pain and trunk muscle strength, researches in this field yielded conflicting results: some found significant weakness of trunk muscles in back pain patients compared with healthy subjects, however many researches did not show any relationship. Objectives: The focus of this study is to assess the trunk muscles strength using isokinetic dynamometer then tries to find a relation between back pain and trunk muscles strength. Materials and Methods: Fifty patients with back pain (BP) and 50 healthy subjects were recruited in this study. The flexors and extensors of the trunk muscles were evaluated by Isokinetic dynamometer and compared with control groups. Results: Patients with acute back pain show a significant reduction of the trunk muscles strengths at 120°/s velocities (p value < 0.05) with reversed flexor/extensor ration in comparison with sound subjects. Such a relationship does not show in subacute or chronic back pain patients. Conclusions: Acute back pain associated with decreased the strength of the trunk flexors and extensors at 120°/s. The trunk muscle reinforcement programs must be considered in-patients with acute back pain.
文摘BACKGROUND： Lower body strength is considered to be a critical component towards successful exercise performance in football players. The aim of this study was to describe the peak isokinetic torque of the knee in professional football players of different League divisions in Cyprus and assess bilateral and unilateral asymmetries of strength. METHODS： Four hundred and twenty-nine professional male football players participated in this study （Division 1, n = 245 and Division 2, n = 184）. The isokinetic muscle function of the knee was measured using the Humac Norm Testing and Rehabilitation system （CSMi Medical ＆ Solution, USA）. Measurements were collected at angle speeds of 60 °/sec and 300 °/sec, for 3 and 25- repetitions respectively. RESULTS： At both angle speeds, peak isokinetic torque of the knee joint was significantly higher in the right and left knees of players in Division 1 （D1） compared to those competing in Division 2 （D2）. At both testing speeds, peak flexor torque of the left hamstrings was significantly higher in players participating in Division 1 compared to those competing in Division 2. The right hamstrings yielded similar results, except at 60 °/sec, where no difference was found between the groups. CONCLUSION： This study provides valuable data regarding the forces produced by the lower body of football players participating in D1 and D2 in Cyprus, whilst also disclosing there to be no bilateral imbalances or abnormal H/Q ratios. The results of this study may provide pertinent information that can be used by the coaching staff for training and recruiting purposes.
文摘Purpose The present study examined the effects of a reciprocal,slow velocity forearm flexion and extension task on fatigue-induced changes in isokinetic torque,agonist and antagonist muscle activation,and coactivation ratios at slow and moderate velocities.Methods Nine women(mean±SD:age=21.0±1.7 years;body mass=68.1±8.2 kg;height=167.4±7.2 cm)completed pre-testing for forearm flexion and extension isokinetic peak torque at 60 and 180°/s,a fatiguing task of 50 maximal,recip-rocal,isokinetic muscle actions at 60°/s,and post-testing.The amplitude(AMP)of the electromyographic(EMG)signals from the biceps and triceps were simultaneously recorded.Torque and EMG AMP were normalized to the corresponding values from the pre-testing peak torque movements.Repeated measures ANOVAs and pairwise comparisons were used to identify mean changes in torque,EMG AMP,and coactivation ratios.Results The torque analyses indicated significant decreases from pre-to post-testing for forearm flexion(14.1%±5.0%;P<0.001)and extension(25.4%±12.2%;P<0.001)at 60°.At 180°/s there was a significant decrease,collapsed across the forearm movements(24.7%±11.7%;P<0.001).For EMG AMP and coactivation ratios,there were no changes(P>0.05)from pre-to post-testing for either velocity or movement.Conclusions The torque responses were velocity-specific,with greater fatigability exhibited for forearm extension versus flexion at 60°/s,but no differences at 180°/s.The parallel EMG AMP responses between the agonist and antagonist muscles for both velocities supported the lack of fatigue-induced changes in coactivation ratios.Thus,our results demonstrated that fatigue-induced decreases in torque were not attributable to increases in antagonist activation or coactivation.
基金supported by the National Natural Science Foundation of China(Grant Nos.51575338,51575407,51475427 and 61733011)the Fundamental Research Funds for the Central Universities(Grant No.17JCYB03)
文摘It is of great importance to decode motion dynamics of the human limbs such as the joint angle and torque in order to improve the functionality and provide more intuitive control in human-machine collaborative systems. In order to achieve feasible prediction,both the surface electromyography(sEMG) and A-mode ultrasound were applied to detect muscle deformation and motor intent.Six abled subjects were recruited to perform five trails elbow isokinetic flexion and extension, and each trail contained five repetitions, with muscle deformation and s EMG signals recorded simultaneously. The experimental datasets were categorized as:the ultrasound-EMG combined datasets, ultrasound-only datasets and EMG-only datasets. The support vector machine(SVM)regression model was developed for both elbow joint angle and torque prediction, based on the above three kinds of datasets. The root-mean-square error(RMSE) and the correlation coefficients(R) were applied to evaluate the prediction accuracy. The results across all the subjects for different datasets indicated that the combined datasets and the ultrasound datasets were superior to the sEMG datasets both on elbow joint angle and torque prediction, and there were no significant differences between the combined datasets and the ultrasound datasets. It turns out that elbow angle and torque can be reconstructed by A-mode ultrasound, and the significant findings pave the way towards the application of musculature-driven human-machine collaborative systems.
文摘Isokinetic relationships of the series of electrophilic substitution reactions of o-substi- tuted phenylmercurials are studied, and the results show, for the first time, that isokinetic correlation analysis can reveal the dominant factor in the system of the reactions. The analysis of SE2 of o-substituted phenylmercuric chlorides indicates that the steric effect of o-substituents is the pre-dominant factor when I2 is used as electrophilic agent, however, the electronic effect of o-substituents would become the predominant factor when HCl is used as the electrophilic agent. In SE1 of o-substituted phenylmercuric chlorides, the results of the analysis display that the predomi-nant factor is the field effects of o-substituents. The determination of predominant factors in those reactions would provide further scientific basis for those reaction mechanisms.
文摘Purpose To determine the amount of familiarization sessions required by breast cancer survivors to achieve a reliable meas-urement of muscle function assessed using isokinetic dynamometry.Methods Twenty-six breast cancer survivors performed three isokinetic knee extension tests separated by,at least,48 h.The isokinetic testing protocol included one warm-up set of 10 submaximal knee extensions at 120°/s,followed by two sets of four maximal knee extensions at 60°/s,with 2-min rest interval between sets.Peak torque(PT),time to peak torque(TPT),angle of peak torque(APT),and average power(AP)of each trial was used for the assessment of testing reliability.Percentage change in the mean,typical error,coefficient of variation and intraclass correlation coefficients(ICC2.1)were calculated to determine test-retest reliability.Results For PT,change in mean was lower between trials 2 and 3 than between trials 1 and 2(4.18% and 13.18%,respec-tively),and ICC was greater between trials 2 and 3 than between trials 1 and 2(0.962 and 0.818,respectively).For TPT and APT,ICC was clinically acceptable only between trials 2 and 3(0.757 and 0.803,respectively).For AP,change in mean was clinically acceptable between trials 2 and 3(9.84%),while ICC met acceptable reliability between both,trials 1 and 2 and,trials 2 and 3(0.756 and 0.891,respectively).Conclusion At least one familiarization session is adequate to achieve reliable measurements of muscle function using isokinetic dynamometry,while avoiding the impact of learning effect of the measurements in breast cancer survivors.
文摘Purpose Muscle strength and power are important requirements in many sports.The correlation of jumping performance as manifestation of muscle power and squatting one-repetition maximum(1RM)has been shown in several investigations.Correlations with maximum force in a linear isokinetic leg press are still pending.Since different testing devices produce different relationships and rotational isokinetic measurements show conflicting results,further evidence is needed.Methods We investigated the correlation of isokinetic leg press force at 0.1 m/s and 0.7 m/s with squat 1RM and jumping performance in different vertical jumps.Results The results show medium to strong,significant correlations for isokinetic force at 0.1 m/s with squat-and counter-movement-jump performance,whereas isokinetic force at 0.7 m/s showed strong,significant correlations for both jumping tests.Drop jump performance(dropping heights:20,30,40,and 50 cm,respectively)reveals weak to medium,significant correlations with isokinetic force at 0.1 m/s and weak,significant correlations with isokinetic force at 0.7 m/s.Squat 1RM displays strong relationships to isokinetic force with greater coefficients regarding higher movement speed in the isokinetic condition.Conclusion The maximum strength of the leg extensors displays a basic requirement for vertical jumping with great motion in knee-and hip-joints and should be considered in training programs.For vertical jumps that are mainly generated via ankle motion,maximum strength of knee-and hip-extensors plays an indirect role to guarantee for performance-enhancing mechanisms.Additionally,in strength testing,different manifestations of strength performance should carefully be taken into account.
文摘Background:For the past 30 years,the hamstring(H)-to-quadriceps(Q)(H:Q)torque ratio has been considered an important index of muscle strength imbalance around the knee joint.The purpose of this systematic review was to examine the value of H:Q torque ratio as an independent risk factor for hamstring and anterior cruciate ligament(ACL)injuries.Methods:Database searches were performed to identify all relevant articles in PubMed,MEDLINE,Cochrane Library,and Scopus.Prospective studies evaluating the conventional(concentric H:Q),functional(eccentric H:concentric Q),and mixed(eccentric H at 300/s:concentric Q at2400/s)H:Q ratios as risk factors for occurrence of hamstring muscle strain or ACL injury were considered.Risk of bias was assessed using the Quality In Prognosis Studies tool.Results:Eighteen included studies reported 585 hamstrings injuries in 2945 participants,and 5 studies documented 128 ACL injuries in 2772participants.Best evidence synthesis analysis indicated that there is very limited evidence that H:Q strength ratio is an independent risk factor for hamstring and ACL injury,and this was not different between various ratio types.Methodological limitations and limited evidence for ACL injuries and some ratio types might have influenced these results.Conclusion:The H:Q ratio has limited value for the prediction of ACL and hamstring injuries.Monitoring strength imbalances along with other modifiable factors during the entire competitive season may provide a better understanding of the association between H:Q ratio and injury.
基金financial support provided by the National Key Technology R&D Program during the 11th Five-Year Period (No. 2006BAK03B05)the National Natural Science Foundation of China (Nos.50534090, 50674090 and 50804047)+1 种基金the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology (Nos.08KF14 and SKLCRSM09X04)the Scien-tific Research Foundation of China University of Mining & Technology (No.2007A001)
文摘In order to investigate the oxidation kinetics of gas coal at low temperatures, we derived a rate equation of oxygen consumption during low-temperature oxidation of gas coal and deduced an E-c equation, expressing the relation between active energy E and oxygen concentration c. The reaction order n and active energy E were calculated with this equation based on experiments of static oxygen consumption tests. In addition, we proved the rationality of the E-c equation using a kinetic compensation effect and obtained the isokinetic temperature Tc. The results show that： 1） the gas coal oxidizes easily with increasing temperature and the oxidation tends to be spontaneous at higher temperatures; 2） the oxygen concentration c affects oxygen consumption very much at lower temperatures but has only a small effect at higher temperatures; 3） the isokinetic temperature Tc was 127 ℃ which has been experimentally validated as the key turning point during low-temperature spontaneous combustion of gas coal.
文摘Background: Infrared thermographic imaging(IRTG) is a safe and reliable technology used to monitor skin temperature. The main aim of our study was to evaluate the relationship between skin temperature changes and muscle fatigue in order to answer the main research question if IRTG can be used to monitor muscle fatigue.Methods: This was a case study performed on a 23-year-old trained middle distance runner. After warm-up the subject was exercising on the dynamometer for 7.5 min at 120?/s performing only concentric contractions of quadriceps. At the same time IRTG recording of both(exercising and non-exercising) quadriceps was performed.Results: A correlational analysis that was performed in order to quantify the relationship between power and temperature change over time has shown that there is a significant negative correlation between skin temperature increase and power decrease(r = -0.543, p = 0.036) of exercising quadriceps. In linear regression model the exercising quadriceps power could be predicted from skin temperature. No such relationships were noted for the non-exercising limb that served as a control.Conclusion: We believe that correlation between skin temperature change and muscle power output as described in this case study deserves further analysis on the larger sample including subjects of the different ages, health status, and physical abilities in order to create a new tool for monitoring the muscle fatigue.
文摘Skeletal muscle stiffness is altered after spinal cord injury(SCI).Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI.The study used magnetic resonance elastography to assess the changes in stiffness after chronic SCI compared to matched able-bodied controls and determine its association with muscle size,spasticity,and peak torque in persons with SCI.Previous studies examined the association between muscle stiffness and spasticity,however,we are unaware of other studies that examined the effects of muscle composition on stiffness after SCI.Ten participants(one female)with chronic SCI and eight(one female)matched able-bodied controls participated in this cross-sectional study.Magnetic resonance elastography was utilized to monitor stiffness derived from shear waves propagation.Modified Ashworth scale was used to evaluate spasticity scores in a blinded fashion.Peak isometric and isokinetic torques were measured using a biodex dynamometer.Stiffness values were non-significantly lower(12.5%;P=0.3)in the SCI group compared to able-bodied controls.Moreover,stiffness was positively related to vastus lateralis whole muscle cross-sectional area(CSA)(r2=0.64,P<0.005)and vastus lateralis absolute muscle CSA after accounting for intramuscular fat(r2=0.78,P<0.0007).Stiffness was also positively correlated to both isometric(r2=0.55-0.57,P<0.05)and isokinetic peak(r2=0.46-0.48,P<0.05)torques.Our results suggest that larger clinical trial is warranted to confirm the preliminary findings that muscle stiffness is altered after SCI compared to healthy controls.Stiffness appeared to be influenced by infiltration of intramuscular fat and modestly by the spasticity of the paralyzed muscles.The preliminary data indicated that the relationship between muscle stiffness and peak torque is not altered with changing the frequency of pulses or angular velocities.All study procedures were approved by the Institutional Review Board at the Hunter Holmes McGuire VA Medical Center,USA(IRB#:02314)on May 3,2017.
基金"Ministry" of Science and Technology,Taiwan,China(NSC 97-2622-B003-001-CC2)Tonic Fitness Technology Inc.(Magtonic,Taiwan,China) provided the funding and the customized vibration platform
文摘Purpose:The purpose of this study was to compare the effects of an 8-week whole-body vibration training program in various frequency and amplitude settings under the same acceleration on the strength and power of the knee extensors.Methods:Sixty-four young participants were randomly assigned to 1 of 4 groups with the same acceleration(4 g):high frequency and low amplitude(n = 16,32 Hz,1 mm) group,medium frequency and medium amplitude(n = 16,18 Hz,3 mm) group,low frequency and high amplitude(n = 16,3 Hz,114 mm) group,and control(n = 16,no vibration) group.All participants underwent 8 weeks of training with body mass dynamic squats,3 sessions a week.Results:The results showed that the high frequency and low amplitude group increased significantly in isometric contraction strength and 120°/s isokinetic concentric contraction strength;the medium frequency and medium amplitude group increased significantly in 60°/s and 120°/s isokinetic strength of both concentric and eccentric contraction;and the low frequency and high amplitude group increased significantly in 60°/s and 120°/s isokinetic eccentric contraction strength.Conclusion:All frequency and amplitude settings in the 8-week whole-body vibration training increased muscle strength,but different settings resulted in various neuromuscular adaptations despite the same intensity.
文摘Background： Various training schemes have sought to improve golf-related athletic ability. In the golf swing motion, the muscle strengths of the core and arms play important roles, where a difference typically exists in the power of arm muscles between the dominant and non- dominant sides. The purposes of this study were to determine the effects of exercises strengthening the core and non-dominant arm muscles of elite golf players （handicap 〈 3） on the increase in drive distance, and to present a corresponding training scheme aimed at improving golf performance ability. Methods： Sixty elite golfers were randomized into the control group （CG, n = 20）, core exercise group （CEG, n = 20）, and group receiving a combination of muscle strengthening exercises of the non-dominant arm and the core （NCEG, n = 20）. The 3 groups conducted the corresponding exercises for 8 weeks, after which the changes in drive distances and isokinetic strength were measured. Results： Significant differences in the overall improvement of drive distance were observed among the groups （p 〈 0.001）. Enhancement of the drive distance of NCEG was greater than both CG （p 〈 0.001） and CEG （p = 0.001）. Except for trunk flexion, all variables of the measurements of isokinetic strength for NCEG also showed the highest values compared to the other groups. Examination of the correlation between drive distance and isokinetic strength revealed significant correlations of all variables except trunk flexion, wrist extension, and elbow extension. Conclusion： The combination of core and non-dominant arm strength exercises can provide a more effective specialized training program than core alone training for golfers to increase their drive distances.
文摘This study was designed to investigate the effects of kinesio tape （KT） on functional performance of female basketball players with and without chronic ankle instability （CAI）. The players with （n = 15） and without ankle instability （n = 16） were enrolled. KT was applied with tension in the instability group and without tension in the control group. Before KT application, 30 minutes and 48 hours after application; muscle strength and endurance were tested in plantar flexion and dorsiflexion, joint position sense was measured in ankle dorsiflexion and plantar flexion using a dynamometer. Dynamic postural stability was evaluated with a balance system between the levels of 12-4. Vertical jumping heights were measured by jump-meter. The results were statistically assessed by SPSS 19 version. In CAI group, dynamic postural stability showed statistically significant improvement in both legs overall （P 〈 0.0001）, antero-posterior （P 〈 0.004） and medio-lateral indexes （P 〈 0.009）. CAI group showed significant improvements in one-leg postural stability overall, antero-posterior and medio-lateral indexes after 48 hours （P 〈 0.011, P 〈 0.022, P 〈 0.038, respectively）. Joint position sense, vertical jump height and muscle strength and endurance were also compared in both groups, and there was no significant difference between the groups. Postural stability indexes were decreased by supporting fimction of KT to the ankle. As a result, we can say that KT has a beneficial effect on maintaining posture by correcting standing kinematics in cases with CAl. We may suggest that KT can be utilized in preventing the injuries in CAI.
文摘An isokinetic sampling probe is designed and constructed to measure entrained liquid droplet fluxes in separated gasliquid pipe flows. This probe also has the capability of working as a non-standard Pitot tube when the sampling is stopped. CFD simulations using the commercial software Ansys CFX were carried out for single phase gas flow to analyze the non-standard design. Pitot tube velocity calculations and isokinetic sampling conditions were studied. The predicted results were compared against theoretical velocity profiles from the literature and with gas single phase experimental data acquired in a horizontal 49 m long steel pipeline with an internal diameter of 69 mm. The experiments were done by using a dense gas (SF6) at 7 bara. An asymmetry of the experimental velocity profiles reproduced with the numerical simulations. The CFD simulations made it possible to verify the design and predict and correct an installation problem.
文摘Vitamin C is a popular supplement in exercise and sport for its chemical properties i.e.v antioxidant capabilities. However, no clear role has been established for vitamin C supplementation (VCS) within these areas despite nearly a century’s worth of ongoing research. This study examined peak muscular pushing force (PMF) before and after a VCS intervention, 250 mg every 12 hrs for 28 days, in nine participants whom were naive to VCS and resistance exercise (RE). A dynamometer was used to perform two RE bouts, pre- and post-intervention, that quantified PMF during a state of exercise-induced oxidative stress (EI-OS). Saliva was collected for EIOS analysis from each participant before and after each RE bout;salivary vitamin C (VC) and free salivary malondialdehyde (MDA) were the examined biomarkers. PMF increased significantly post-intervention (405.48 ± 92.75 m·kg·s-2) from baseline (368.31 ± 76.36 m·kg·s-2, p < 0.05). MDA elevated significantly after the pre-intervention RE bout (0.385 ± 0.017 μg/mL) and the post-intervention RE bout (0.373 ± 0.014 μg/mL) compared to the baseline measures (0.373 ± 0.014 μg/mL, 0.359 ± 0.008 μg/mL;p < 0.01);a significant reduction in MDA was observed post-intervention, confirming vitamin C’s ability to reduce oxidative stress (p < 0.05). VC increased post-intervention (1.22 ± 0.73 μg/mL) from baseline (0.47 ± 0.51 μg/mL, p < 0.001). The results from this study suggest VCS is capable of increasing PMF by reducing EIOS in untrained individuals, and can be possibly used for enhancing resistance-exercise performance.
基金supported by the Innovative Research Team of Henan Polytechnic University (T2020-3).
文摘As a major equipment for thermal power plants,the main function of coarse powder separators is to separate particles into size groups according to particle diameter.With the rising coal prices,power plants are using more low-density lignite.Consequently,the original equipment does not operate under normal conditions.Therefore,to return the equipment to normal operating conditions,the isokinetic sampling method,computational fluid dynamics(CFD),and discrete phase model(DPM)based on the Euler-Lagrange method are applied in this research to analyze the effect of baffle shapes,baffle numbers,and centrifugal blades on the equipment performance index,like R90.The shape of the baffle plate was optimized and improved.Preferential method was applied to determine the optimal number of baffles to ensure normal working conditions.Results show that curved baffles can suppress the axial negative gradient field below themselves better than rectangular baffles.The curved baffles selected by the optimal seeking method make full use of the negative axial gradient field and provide the particles entering the separation zone at tangential velocity in advance with the addition of centrifugal blades.Thus,pre-separation can be realized.The R90 is 5 at the separator outlet and 95 at the powder return port,indicating that the output capacity of the separator returned to a reasonable operating performance.
文摘In order to determine a rational protocol for isotonic training from macroscopic angle, five training protocols were designed, particularly protocols composed of pure eccentric contraction with heavy resistance in different propotions. The study results indicated that the protocol mixed with faster speed eccentric training,being more rational than traditional isotonic training and pure isotonic eccentric training, had the most all - round effects(including change of musle size, isotonic strength, musle power and et al. ). The protocol principle mixed with faster speed eccentric training may be widely used in rehabilitation and sports training,especially in the sports events of strength resistance. The significance to study the ratio of eccentric contaction to concentic contraction was suggested.
