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Torque, Work, Power, and Muscle Activity Analysis According to Self-Selected Slow, Moderate, and Fast Angular Velocity for Knee Extension
J Kor Phys Ther 2024;36(3):103-109
Published online June 30, 2024;  https://doi.org/10.18857/jkpt.2024.36.3.103
© 2024 The Korea Society of Physical Therapy.

Jonggeun Woo1, Jiheon Hong1, Jeongwoo Jeon2

1Department of Physical Therapy, College of Health Sciences, Sunmoon University, Asan, Republic of Korea, 2Digital Healthcare Institute, College of Health Sciences, Sunmoon University, Asan, Republic of Korea
Jeongwoo Jeon
E-mail doublej_woo@naver.com
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (RS-2023-00249155).
Received May 27, 2024; Revised June 13, 2024; Accepted June 26, 2024.
This is an Open Access article distribute under the terms of the Creative Commons Attribution Non-commercial License (http://creativecommons.org/license/by-nc/4.0.) which permits unrestricted non-commercial use, distribution,and reproduction in any medium, provided the original work is properly cited.
Abstract
Purpose: The performance of a task is influenced by the perception of its demands and the development of a response according to the movement pattern. This study aims to compare the change in kinetic variables and quadriceps muscle activity according to demands on angular velocity.
Methods: Thirty-eight participants performed knee extensions at self-selective angular velocities of slow, moderate, and fast. Angular velocity, kinetic variables, and muscle activity (vastus medialis, vastus lateralis, and rectus femoris) were measured using a dynamometer and surface electromyography. kinetic variables and muscle activity of the knee extensors at three self-selected angular velocities were compared and correlations between the variables were analyzed.
Results: There were significant differences in muscle activity and kinetic variables among angular velocities (p<0.001). Self-selective angular velocity was positively correlated with muscle activities and kinetic variables (p<0.001). The power in fast was 40 times higher than that in slow velocity.
Conclusion: The simultaneous increase in angular velocity and force output was based on increased effort. The highest power was indicated for the fastest movement. We discovered that muscle activity and torque increased at a similar rate for increasing demands on angular velocity. The individual’s most appropriate pattern would have been applied at the movement of self-selective angular velocity, and fast movement is considered to have the highest efficiency.
Keywords : Biomechanics, Knee extensors, Movement angular velocity, Self-selective angular velocity, Muscle activity
INTRODUCTION

The definition of “muscular strength” is the ability to exert force on an external object or resistance. Higher levels of muscular strength can increase functional performance and reduce the risk of injury.1 Resistance training is commonly used to improve muscular strength. The intensity of the resistance training program can be modified using the following variables: resistance, angular velocity of movement, distance moved, exercise selection and order, number of sets and repetitions, frequency, and resting period.2 In order to the scientific design of resistance training, changes in biomechanical data including muscle activity should be determined in response to systematically increasing the demands placed on the body. Considering the most used isotonic exercise as an example, an increase in load results in an increase in the exercise demand for the subject.3

Isotonic exercise, widely recognized as a predominant strength training technique, encounters a limitation where the maximal resistance is confined to the load at the weakest point across the full range of motion.3 Conversely, isokinetic exercise, by setting a constant maximum velocity, theoretically enables maximal force generation throughout the entire active range of motion.4 Previous studies comparing isokinetic variables (torque, power, work, etc.) according to angular velocity used constant angular velocity for fast (e.g., 200-300°/s) and slow (e.g., 60-120°/s) velocities.5-11 Another study reported a linear model of the force-velocity relationship in which an increase in velocity was accompanied by a decrease in muscular strength.12 In isokinetic exercise, angular velocity is inversely proportional to torque and work values, while it is proportional to power.13 However, muscle force/torque control was influenced by task, sex, age, etc.13,14 A study of the relationship between force and electromyography (EMG) for knee extension discovered that it can be used as a rough estimate of force, despite slight deviations in the linearity of the quadriceps EMG.15 However, there have been inconsistent reports of an increase, a decrease and no change in EMG amplitude with increasing angular velocity.3,5,6,9,11,16 In isokinetic exercise, the participant is required to exert their best effort in an entire range of motion (ROM) while the selected maximum angular velocity is limited by the exoskeletal device.4 Because participants require maximum effort for both angular velocities, it can be considered that there are similar performance demands. However, for the generally applied isokinetic exercise, the question regarding the exercise demand for the subject remains. The way an individual responds to performing a given task is influenced by the perception of the task,s demands and the scope of this response runs along a continuum.17

Therefore, to determine the effect of angular velocity, an investigation of the effect of different demands on velocity rather than specifically constrained velocity is necessary. This study aims to compare the change in the kinetic variables (peak torque, PT; average torque, AT; total work, TW; peak power, PP; and average power, AP), and quadriceps concentric muscle activity (EMG activity) according to changes in the demand for movement angular velocity and the correlation between velocity and acquired data.

Our research hypotheses are as follows: 1) the performance of a task would be influenced by the perception of its demands and the development of a response according to the movement pattern. 2) As angular velocity increases, the demands of performing a task will increase. 3) As angular velocity increases, the kinetic variables will increase. 4) As angular velocity increases, muscle activity will increase.

METHODS

1. Subjects

In this cross-sectional study, healthy young adults were recruited through printed and electronic advertisements on notice boards in the university from June 2021 to December 2021. Subjects who were physically active and not currently involved in another exercise program participated in this study. Participants had no previous lower limb injury, neurologic disorder, or cardiovascular disease. In addition, people who were deemed unsuitable for participation by the researcher were unable to participate. A total of 38 healthy young adults (19 men, 19 women, age=23.2±2.1 years, height=166.8±8.6cm, body mass=63.0±13.8kg, body mass index=22.4±3.4kg/m2) volunteered to participate in this study. Data from all enrolled participants were used for analysis.

This study has been approved by the Institutional Review Board of the authors’ affiliated institutions. Additionally, this study was conducted in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from all participants.

2. Experimental procedures

1) Measurement

(1) Knee extensor muscle function at the self-selective angular velocity

An isokinetic dynamometer (HUMAC NORM, CSMI Medical Solutions, Stoughton, USA) was used to assess knee extensor muscle function (kinetic variables) at self-selected slow, moderate, and fast angular velocities (Figure 1). Analog output data were converted to digital in the same data acquisition system of the dynamometer and recorded in synchronization with the EMG data. Kinetic variables data collected from the dynamometer were sampled at 1,000Hz and smoothed using a rolling average calculated every 50 samples.

Fig. 1. Isokinetic dynamometer

Before obtaining the measurements, participants performed a 5-minute warm-up at their own pace using a cycle ergometer (NB 7.0r Recumbent Bike, New Balance fitness, Ohio, USA). Subsequently, 3-minute after the warm-up, participants were instructed to sit in a dynamometer chair with a hip flexion of 85°. The axis of the dynamometer was aligned with the lateral epicondyle of the knee, and the force pad was placed approximately 3cm above the medial malleolus. The trunk and the thighs were secured using straps. The dominant leg was measured, which was identified as the leg usually used to kick the ball.12 Before performing knee extension, participants were asked to determine and move at three subjectively perceived (self-selective) angular velocities: slow, moderate, and fast. Participants performed concentric knee extension at three self-selected angular velocities using the isotonic mode of the dynamometer. In isotonic mode, the resistance value was set to zero (no load). In other words, according to these settings, participants were able to freely perform knee extension except for the force pad weight of the dynamometer. The knee joint,s ROM was set from 90° flexion to maximal voluntary knee extension (0°). The order of the knee extension tests at three self-selective angular velocities was assigned randomly to each participant and separated by a 5-minute rest interval to minimize muscle fatigue. Three trials were performed at each angular velocity, and a 30s rest was allowed between each trial.

Three self-selected angular velocity values (in degrees per second) were extracted from raw data obtained during isotonic contractions. This was calculated as the average of the recorded angular velocities within the ROM while performing knee extension. To evaluate knee extensor function, we determined the kinetic variables (PT, AT, TW, PP, and AP). All kinetic variables were expressed as the mean values of three trials. PT, TW, PP, and AP were obtained through the dynamometer’s report. We calculated AT directly from extracted raw data. PT (Newton meters; N·m) and AT (N·m) refer to the maximum and mean torque values, respectively, and TW (joule, J) represents the total work performed by the knee joint.18 To compensate for individual differences related to body mass, the measured values were normalized for each.3

(2) Electromyography

The EMG measurements were conducted using the wireless surface EMG system (Zero Wire EMG, Aurion, Oderzo, Italy)(Figure 2). Muscle activity data were exported to the A/D converter of the EMG recording system and then collected and analyzed using MyoRESEARCH software (XP Master, version 1.07.1, Noraxon, Arizona, USA) installed on a personal computer. EMG data were acquired for the vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) muscles during knee extension with three self-selective angular velocities. Because agonist muscles have a primary role in generating force in the directions prescribed, the activity of these muscles was included in the measurements.19 Skin preparation, such as shaving the electrode sites and cleaning the skin with rubbing alcohol, followed the Surface EMG for the Non-invasive Assessment of Muscles guidelines while attachment placement of the Ag-AgCl electrode was determined according to the previous study.3,20

Fig. 2. Wireless surface electromyography system

To normalize EMG data, participants completed a maximal voluntary isometric contraction (MVIC) test of the knee extensors using the isometric mode of an isokinetic dynamometer. In the MVIC test, the knee and hip joints of the examined limb (dominant limb) were maintained in 60° and 90° flexion, respectively.21,22 Three 5-second trials were recorded with 2 minutes of rest in between. The first and last seconds were discarded, and the RMS value for the 3 seconds present in the middle was calculated. The highest value of the three MVIC consecutive tests was used for analysis.23 EMG signals obtained during the knee extension were normalized to the MVIC (%MVIC). All raw EMG signals acquired during knee extension and MVIC tests were sampled at 1,000Hz and were band pass-filtered between 20 and 450Hz. The filtered signals were full wave rectified and smoothed using the root mean square (RMS) with a 100ms window.

3. Statistical analysis

The Shapiro-Wilk test was used for the normality test of all data. Normality was not assumed for the variables collected in this study, which led to the use of nonparametric statistics. Kruskal–Wallis one-way analysis of variance (two-tailed, significance level α=0.05) was applied to compare the kinetic variables and muscle activity of the knee extensors at three self-selective angular velocities. A Mann-Whitney U test was used for post hoc analysis, and Bonferroni correction (0.05/3) was applied (two-tailed, significance level α=0.0167). Spearman rank-order correlation test was used to analyze the correlation of the self-selective slow, moderate, and fast angular velocities with kinetic variables and muscle activity (0.0-0.1: no correlation, 0.1-0.4: weak correlation, 0.4-0.6: moderate correlation, 0.6-0.8: strong correlation, >0.8: very strong correlation).24 All data were analyzed using IBM SPSS (IBM Corp., Armonk, NY, USA). p<0.05 was considered statistically significant and effect sizes (ES) were calculated using Cohen’s d.

RESULTS

Table 1 depicts the differences in the kinetic variables (PT, AT, TW, PP, and AP) and muscle activity (VM, VL, and RF) of the knee extensors during concentric contraction according to the three self-selective angular velocities. The self-selective slow, moderate, and fast angular velocities (°/s) of the knee extension were measured to be 27.82±18.65 (range: 29.48-48.26), 80.06±19.66 (43.57-142.32), and 122.6±23.31 (76.66-192.15), respectively. The relative ratios of moderate and fast angular velocities to slow velocity were 287.78% and 440.69%, respectively. Also, the relative ratio of fast to moderate angular velocity was 153.14%. Significant differences were observed in the kinetic variables among the angular velocities (p<0.001). According to the results of the Mann–Whitney post hoc tests, PT, AT, TW, PP, and AP values at fast angular velocity were significantly greater than those at other velocities (p<0.001). These values were also significantly higher at moderate than at slow velocity (p<0.001). Additionally, significant differences were observed in muscle activity according to angular velocity. The result of the post hoc tests revealed that VM, VL, and RF muscle activity at fast angular velocity were significantly higher than at other velocities (p<0.001). Muscle activity at moderate angular velocity was significantly greater than at slow velocity (VM; p<0.001, VL; p<0.01, RF; p<0.05).

Comparison between kinetic variables and muscle activity of knee extensors according to self-selective angular velocities (N=38)

Variable Slow Moderate Fast df Chi-square p-valuea
Self-selective angular velocity (°/s) 27.82 (18.65) 80.06 (19.66) 122.60 (23.31)
% Slow velocityb 100 287.78 440.69
Kinetic variables
Peak torque (Nm/kg) 0.08 (0.03) 0.24 (0.10) 0.62 (0.26) 2 90.432 <0.001*,**,
Average torque (Nm/kg) 0.04 (0.04) 0.09 (0.07) 0.19 (0.10) 2 54.704 <0.001*,**,
Total work (J/kg) 0.04 (0.03) 0.17 (0.09) 0.55 (0.29) 2 88.736 <0.001*,**,
Peak power (W) 3.18 (3.65) 25.16 (18.29) 130.76 (90.80) 2 89.845 <0.001*,**,
Average power (W) 1.24 (2.16) 11.66 (8.32) 60.37 (42.48) 2 89.816 <0.001*,**,
Muscle activity (% MVIC)
Vastus medialis 13.95 (7.70) 22.63 (13.49) 67.06 (38.21) 2 45.684 <0.001*,**,
Vastus lateralis 16.77 (7.94) 24.89 (16.37) 68.01 (43.29) 2 45.684 <0.001*,**,
Rectus femoris 19.06 (9.66) 25.18 (11.44) 57.68 (25.61) 2 38.105 <0.001*,**,

Data are presented as mean (standard deviation). df: degrees of freedom, MVIC: maximal voluntary isometric contraction. aPost hoc test; Mann–Whitney U test, bThe relative ratios of self-selective moderate and fast angular velocities to slow velocity in knee extension. *slow < moderate, **slow < fast, moderate < fast.



Figure 3 presents the correlation between the self-selective angular velocity of knee extension and kinetic variables. The angular velocity has a very strong positive correlation with PT, TW, AP, and PP (p<0.001), and a strong positive correlation with AT (p<0.001). Figure 4 illustrates the correlation between angular velocity and muscle activity in knee extensors. The angular velocity has a strong positive correlation with each muscle activity corresponding to VMO, VL, and RF (p<0.001).

Fig. 3. Correlation between self-selective angular velocity of knee extension and kinetic variables
Fig. 4. Correlation between self-selective angular velocity of knee extension and muscle activity
DISCUSSION

This study investigated the changes in kinetic variables and muscle activity of the quadriceps according to the increase in demand for movement angular velocity. The angular velocities of the self-selective fast and moderate were 122.6°/s, and 80.06°/s, respectively, which was 4.4 times and 2.9 times quicker than that of the slow velocity (27.82°/s).

In previous studies, the increase or decrease in muscle activity with an increase in angular velocity was debated.3,5,6,9,11,16 Tillin et al.25 suggested that the effect of contraction speed was not on neuromuscular activation, but rather on the intrinsic property of contracting myofibers. Remarkably, the muscle activities and AT of the fast angular velocity were increased 3 to 4.8 times as compared with the slow velocity, which was similar to the rate of angular velocity increase. Humans recognize the demands of a certain task and perform the required action using appropriate movement strategies.17 Faster moments require more motor unit recruitment and increased utilization of fast-twitch fibers, resulting in higher EMG amplitudes.26 This hypothesis is based on increased effort and the need for greater force output for higher angular velocities. The study participants had increased muscle activity in response to the increased demand for movement angular velocity; therefore, it is thought that angular velocity and AT also increased at a similar rate.

Previous studies on isokinetic movement reported that higher angular velocity was accompanied by decreased torque and working value and increased power.5-11 Interestingly, as compared with the slow demand, the PT and TW of the fast movement request increased 7.8 and 13.8 times in this study. Considering mechanics, acceleration represents the rate at which the angular velocity of an object changes with time, which is given by the direction of the net force acting on that object. As described by Newton’s second law, the magnitude of acceleration is proportional to the net balance of all external forces acting on that object and inversely proportional to the object’s mass. A positive definite external force is torque resulting from muscle contraction and an opposing external force is the sum of the forces that impede movement (gravitational acceleration, friction, etc.).18 In physics, torque is the rotational equivalent of linear force, which represents the capability of a force to produce a change in the rotational motion of the body. Work is a measure of energy transfer that occurs when an object is moved over a distance by an external force, at least part of which is applied in the displacement direction. Therefore, it is related not only to muscular strength but also to the distance of the force.18 Moreover, the increased rate in the work value can be explained by the flowing physical process. An increase in torque with an increase in demand for angular velocity consequently increases the net force, which in turn increases the velocity of the object. As the angular velocity increases during movement of the same distance, time decreases. The increased work value compared with torque is a double result for an increase in muscle contraction and a decrease in movement time. The PP and AP in the fast angular velocity condition were highly affected by the velocity increase, increasing by 41.1 times and 48.7 times, respectively. Power is defined as work (product of force and distance) divided by the unit of time.27 A more notable change in power compared with work is that the power value increases in proportion to the decrease in time because of the increase in movement angular velocity. The inverse relationship between force and angular velocity has been consistently established for isoinertial knee extension movement.12 In this inverse correlation, the maximum power is obtained at the optimal values of force and angular velocity.28

Kinetic variables resulting in higher angular velocity revealed a decrease in muscular strength, torque, and work.6-12 Resistance training with faster lifting velocity produced greater numbers of repetitions at given intensities.29 The results of conventional isokinetic movement studies with a fixed maximum angular velocity are insufficient to explain this phenomenon. The reason for the diversity of observations and conclusions is that subjects perform tasks in which the subject is defined identically in different ways.30 For example, movements that differ only in the magnitude of the distance or inertial load are quantitatively different. The reason for the different results for the increase in angular velocity is that it depends on an individual’s intrinsic myofiber properties.27 Therefore, results for angular velocity obtained using the isokinetic exercise, fixing the maximum velocity with producing the maximum force, should consider velocity as a qualitative variable. To the best of our knowledge, this study is the first to identify kinetic data for increasing demands in terms of angular velocity. In this study, the subjects used their own optimal pattern for each demand. It is thought that the demand for movement angular velocity was influenced as a quantitative factor for the task.

This study has several limitations. First, angular velocity is a continuous variable. However, because this study acquired data for three self-selective angular velocities, a data deficit occurred among the groups. As a result, regression analysis, a parametric statistic, could not be applied. Moreover, further studies are necessary to investigate the results of the regression analysis on the refinement of neuromechanical parameters by acquiring data for various self-selective angular velocities. Second, antagonist muscle activity was not measured in this study. Although we aimed to determine the activity of agonist muscles, which play a primary role in movement, activation of antagonist muscles may play an important role in the magnitude of joint moments. In particular, the activity of these antagonist muscles may differ between males and females. Therefore, further investigation is needed into the level of antagonist muscle activation depending on self-selected movement angular velocity.

We discovered that angular velocity, muscle activity, and AT increased at similar rates with increasing demands for movement angular velocity. The work value increased more than these data did, with power increasing the most. Considering the results, we drew the following three conclusions. First, the change in the kinetic data for increasing movement demands angular velocity is based on the increased efforts focused on musculature to activate fast to quickly accelerate the limb and overcome inertia. Second, in the velocity-force relationship, as the angular velocity increases, force output decreases. However, in this study using self-selected (slow, moderate, fast) angular velocities, both angular velocity and force output increased simultaneously. This may be because the angular velocity of each individual in this study did not reach close to the individual’s maximum velocity. Third, the power of the fast angular velocity request increased 40 times compared to the slow velocity request. The higher angular velocity within the self-selective velocity range can be considered to use a more efficient pattern. Clinically, when designing physical therapy interventions, it is suggested that faster velocities of movement may be a way to increase exercise efficiency despite the fact that it can be a more challenging task with increased effort.

ACKNOWLEDGEMENTS

본 연구는 한국연구재단 기초과학연구의 연구비 지원을 받았음.

References
  1. Stone MH. Position statement: explosive exercise and training. Strength Cond J. 1993;15(3):7-15.
    CrossRef
  2. Ratamess NA, Alvar BA, Evetoch TE et al. Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708.
    Pubmed CrossRef
  3. Purkayastha S, Cramer JT, Trowbridge CA et al. Surface electromyographic amplitude-to-work ratios during isokinetic and isotonic muscle actions. J Athl Train. 2006;41(3):314-20.
    Pubmed KoreaMed
  4. Brown LE. Isokinetics in human performance. USA, Human Kinetics. 2000:171-95.
  5. Cramer JT, Housh TJ, Johnson GO et al. Mechanomyographic amplitude and mean power output during maximal, concentric, isokinetic muscle actions. Muscle Nerve. 2000;23(12):1826-31.
    Pubmed CrossRef
  6. Cramer JT, Housh TJ, Weir JE et al. Power output, mechanomyographic, and electromyographic responses to maximal, concentric, isokinetic muscle actions in men and women. J Strength Cond Res. 2002;16(3):399-408.
    Pubmed CrossRef
  7. Kurdak SS, Özgünen K, Adas Ü et al. Analysis of isokinetic knee extension/flexion in male elite adolescent wrestlers. J Sports Sci Med. 2005;4(4):489-98.
    Pubmed KoreaMed
  8. Gautrey CN, Watson T, Mitchell A. The effect of velocity on load range during isokinetic hip abduction and adduction exercise. Int J Sports Med. 2013;34(7):623-30.
    Pubmed CrossRef
  9. Seger JY, Thorstensson A. Muscle strength and myoelectric activity in prepubertal and adult males and females. Eur J Appl Physiol Occup Physiol. 1994;69(1):81-7.
    Pubmed CrossRef
  10. Wyatt MP, Edwards AM. Comparison of quadriceps and hamstring torque values during isokinetic exercise. J Orthop Sports Phys Ther. 1981;3(2):48-56.
    Pubmed CrossRef
  11. Barnes WS. The relationship of motor-unit activation to isokinetic muscular contraction at different contractile velocities. Phys Ther. 1980;60(9):1152-8.
    Pubmed CrossRef
  12. Iglesias-Soler E, Fariñas J, Mayo X et al. Comparison of different regression models to fit the force-velocity relationship of a knee extension exercise. Sports Biomech. 2019;18(2):174-89.
    Pubmed CrossRef
  13. Pethick J, Taylor MJ, Harridge SD. Aging and skeletal muscle force control: current perspectives and future directions. Scand J Med Sci Sports. 2022;32(10):1430-43.
    Pubmed KoreaMed CrossRef
  14. Harrison S, Clark NC, Ansdell P et al. Sex differences in knee extensor torque control. J Electromyogr Kinesiol. 2023;72:102806.
    Pubmed CrossRef
  15. Alkner BA, Tesch PA, Berg HE. Quadriceps EMG/force relationship in knee extension and leg press. Med Sci Sports Exerc. 2000;32(2):459-63.
    Pubmed CrossRef
  16. Cramer JT, Housh TJ, Weir JP et al. Gender, muscle, and velocity comparisons of mechanomyographic and electromyographic responses during isokinetic muscle actions. Scand J Med Sci Sports. 2004;14(2):116-27.
    Pubmed CrossRef
  17. Dufek JS, Bates BT. The evaluation and prediction of impact forces during landings. Med Sci Sports Exerc. 1990;22(3):370-7.
    Pubmed CrossRef
  18. Wang XF, Ma ZH, Teng XR. Isokinetic strength test of muscle strength and motor function in total knee arthroplasty. Orthop Surg. 2020;12(3):878-89.
    Pubmed KoreaMed CrossRef
  19. Latash ML. Muscle coactivation: definitions, mechanisms, and functions. J Neurophysiol. 2018;120(1):88-104.
    Pubmed KoreaMed CrossRef
  20. Hermens HJ, Freriks B, Disselhorst-Klug C et al. Development of recommendations for SEMG sensors and sensor placement procedures. J Electromyogr Kinesiol. 2000;10(5):361-74.
    Pubmed CrossRef
  21. Briani RV, De Oliveira Silva D, Flóride CS et al. Quadriceps neuromuscular function in women with patellofemoral pain: influences of the type of the task and the level of pain. PLoS One. 2018;13(10):e0205553.
    Pubmed KoreaMed CrossRef
  22. Pincivero DM, Coelho AJ, Campy RM et al. Knee extensor torque and quadriceps femoris EMG during perceptually-guided isometric contractions. J Electromyogr Kinesiol. 2003;13(2):159-67.
    Pubmed CrossRef
  23. Loro WA, Thelen MD, Rosenthal MD et al. The effects of cryotherapy on quadriceps electromyographic activity and isometric strength in patient in the early phases following knee surgery. J Orthop Surg. 2019;27(1):2309499019831454.
    Pubmed CrossRef
  24. Akoglu H. User's guide to correlation coefficients. Turk J Emerg Med. 2018;18(3):91-3.
    Pubmed KoreaMed CrossRef
  25. Tillin NA, Pain MT, Folland JP. Contraction speed and type influences rapid utilisation of available muscle force: neural and contractile mechanisms. J Exp Biol. 2018;221(24):jeb193367.
    Pubmed CrossRef
  26. Sakamoto A, Sinclair PJ. Muscle activations under varying lifting speeds and intensities during bench press. Eur J Appl Physiol. 2012;112(3):1015-25.
    Pubmed CrossRef
  27. Webber SC, Porter MM. Reliability of ankle isometric, isotonic, and isokinetic strength and power testing in older women. Phys Ther. 2010;90(8):1165-75.
    Pubmed CrossRef
  28. Vandewalle H, Peres G, Heller J et al. Force-velocity relationship and maximal power on a cycle ergometer. Correlation with the height of a vertical jump. Eur J Appl Physiol Occup Physiol. 1987;56(6):650-6.
    Pubmed CrossRef
  29. Sakamoto A, Sinclair PJ. Effect of movement velocity on the relationship between training load and the number of repetitions of bench press. J Strength Cond Res. 2006;20(3):523-7.
    Pubmed CrossRef
  30. Corcos DM, Gottlieb GL, Agarwal GC. Organizing principles for single-joint movements. II. A speed-sensitive strategy. J Neurophysiol. 1989;62(2):358-68.
    Pubmed CrossRef


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