
==== Front
Int J Sports Phys Ther
Int J Sports Phys Ther
2159
International Journal of Sports Physical Therapy
2159-2896
NASMI Website: International Journal of Sports Physical Therapy

38576833
95038
10.26603/001c.95038
Clinical Viewpoint
Isokinetic Testing: Why it is More Important Today than Ever
Wilk Kevin E DPT, FAPTA
Arrigo Christopher A MS, PT, ATC
Davies George J PT, DPT, MEd, SCS, ATC, CSCS, FAPTA
1 4 2024
2024
19 4 374380
© The Author(s)
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (4.0) which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.

Isokinetics is a proven method to train and objectively assess the capability of muscle groups, particularly at the knee. The current re-injury rates and less than optimal return to sport percentages seen following anterior cruciate ligament surgery highlights the need for greater focus on what tests and methods are used to make these critical decisions. Isokinetics remains the best single method to objectively determine dynamic muscle strength, power, rate of force development and endurance. These factors make it well-suited to play a crucial role in influencing the appropriate patient progression through a rehabilitation program and assisting in determining return to play readiness following injury or surgery. In this article we will discuss why we believe isokinetics is a useful and necessary testing method, and elucidate testing parameters and goals used during knee extension/flexion assessment.

Isokinetics
Isokinetic Testing
Knee Testing
Return to Sport
Objective Assessment
==== Body
pmcIsokinetics has been used in testing and rehabilitation for the last 60 years. Its most common use has been for selected musculoskeletal injuries at the knee because of the frequency of injury and ease of testing. Looking back historically, several trends can be identified regarding isokinetics, testing, and rehabilitation. Beginning in the 1960s–1970s an integrated approach combining open kinetic chain (OKC) (isolated joint exercises), closed kinetic chain (CKC) (multi-joint exercises), and functional rehabilitation interventions was advocated. The use of OKC Isokinetic testing and rehabilitation peaked in the 1980s, due largely to the increasing body of evidence demonstrating its effectiveness in assessment and rehabilitation of patients with knee injuries. In the 1990s the focus switched to almost exclusively CKC exercises because they were considered more functional and thought to produce fewer rehabilitation complications, compared to OKC exercises. Beginning in the early 2000s an approach best characterized as “Functional rehabilitation” has been employed almost exclusively largely due to the empirical notion that it has a greater specificity to performance. Investigations in the 2020s have shown many patients following injuries/surgeries oftentimes still have residual strength and power deficits rendering them unable to return to their previous levels of performance. Due to these issues with difficulty returning to unrestricted participation, the current trend is heading back to performing objective isokinetic testing to assess the performance capabilities of associated muscle groups, in conjunction with a battery of other functional tests to both guide rehabilitation and determine readiness to resume higher-level activities.

The proven effectiveness of isokinetics and the large number of patients unable to return to pre-injury levels of activity because of significant strength, power and endurance deficits are why we advocate a “Test, Don’t Guess!” approach that makes the data derived from isokinetics a critical part of the return to play methodology. There are 2 imperatives employed when using isokinetic testing. First, it assists in providing objective data to help guide progression through a rehabilitation program, particularly in the advanced phases. Second, isokinetic testing assists the assessment of readiness for discharge aimed at ensuring a successful return to sport (RTS). RTS readiness frequently includes a number of assessments, including patient reported outcomes (PROs) impairment measurements, muscular strength, power and endurance tests, functional performance tests, neuro-cognitive reactive tests,1 and finally sport specific tests.

Recently there have been several articles which have reported a quadriceps strength value of 90% or better when compared to the contralateral (uninjured) knee as one of the four or five criteria to reduce the risk of reinjury to the knee following anterior cruciate ligament (ACL) surgery.2,3 Furthermore, anecdotally clinicians and researchers have repeatedly stated they are looking for limb symmetry of the quadriceps and hamstrings before returning individuals to a running program or sports participants. With these important criteria stated by many – clinicians require an accurate, objective, and reproducible method of testing to ensure these parameters are met prior to returning anyone back to unrestricted athletic participation.

The focus of this clinical commentary is to address testing of muscle strength, power, and endurance. Using the knee as a model, muscle performance testing can be performed using a variety of methods including manual muscle testing (MMT), handheld dynamometry (HHD), isotonic progressive resistive exercise (PREs) testing using knee extensions and/or leg press movements, squatting, and isokinetics. Multi-joint isotonic tests like the leg press or squat may demonstrate a performance weakness, but because multiple muscle groups are being used in the movement the actual point of weakness and degree of deficit within the kinetic chain are difficult to truly isolate.

Objective muscle performance testing using isokinetics has numerous advantages. (Table 1) It can be used for pre-participation screening to identify potential deficits and allow for preventive interventions to reduce injury risk. Isokinetic testing can be used to assess a patient’s status during rehabilitation to guide program progression. The objective documentation provided from isokinetic testing can be used in the development of criteria-based treatment plans. Despite the benefits the trend over the last few decades has been away from isokinetic testing. The movement away from isokinetics has by in large not been replaced with another form of dynamic muscle performance assessment. This lack of objective muscle performance data is partly responsible for the unfavorable RTS4–7 and high reinjury rates8–10currently prevalent following ACL surgery. The criteria needed for an accurate RTS determination are multi-factorial but muscular strength, power, rate of force development, and endurance are critical metrics that should be routinely tested as part of this decision-making process.1 Numerous studies have demonstrated the reliability of isokinetic muscle performance testing.11–14 Additionally, several studies have demonstrated that although the patient is strapped into the isokinetic testing device, it has good validity, and several studies have demonstrated a correlation between isokinetic performance and functional skills.15–17 For these reasons, isokinetic testing is still the “Gold Standard” for measuring dynamic muscle performance.

Table 1. Advantages of Isokinetic Testing18

Provides reliable objective documentation of dynamic muscle performance

Efficient: loads a dynamically contracting muscle to its maximum capability at all points throughout the range of motion

Because of the accommodating resistance, a muscle can be challenged to its maximal capability through an entire range of motion (physiologic Blix curve)

Muscle groups can be isolated for testing and rehabilitation

Inherently safe for pain and fatigue

Validity based on correlations with other functional tests

Concentric isokinetic exercises produce minimal postexercise delayed-onset muscle soreness

Exercise at different angular velocities through a velocity spectrum

Because of specificity of training, exercising at the faster angular velocities at higher intensities can recruit fast-twitch muscle fibers which are critically important in functional activities. There is the potential to increase muscle power, rate of force development (RFD) quickness of muscle force development, time rate of torque development TRTD), torque acceleration energy (TAE); all are important for athletic performance.

The reciprocal innervation time is the time from contracting one muscle group (agonist) (quadriceps), and then reciprocally contracting the opposite muscle group (antagnoist) (hamstrings). When the patient exercises at faster angular velocities in a reciprocal manner (contracting quads and then immediately the hamstring, etc.), it decreases the reciprocal innervation time.

Joint compressive forces decrease with higher angular velocities (fluid film lubrication model)

Bernoulli’s principle indicates that the faster a surface (articular cartilage) moves over fluid, (synovial fluid in a joint), the less the compressive forces on the surface

There is a 30°/s physiologic (strengthening) overflow to slower angular velocities with isokinetic resistance

There is a 30°–40° range of motion strengthening overflow during performance of short-arc exercises

Computerized feedback allows improvement in torque control accuracy

Real-time feedback is available to the patient for motivation during exercise

Short arc testing and/or using a proximally placed pad can decrease anterior tibial translation

(Table from: Davies, GJ, Riemann, BL, Ellenbecker, TS. Role of Isokinetic Testing and Training after ACL Injury and Reconstruction. In F. R. Noyes, S. Barber-Westin (Eds.), ACL Injuries in the Female Athlete. Springer-Nature, 2018)18

In contrast, performing isometric knee testing at a 90-degree angle with the patient in the seated position has become a popular assessment for quadriceps strength. There are several limitations to this technique: 1) the 90 degree angle pre-stretches the distal quads, but shortens the rectus femoris, 2) if this position is used, perhaps it should replicate the functional position of the hips with standing, walking or running by having the patient laying supine on the table, 3) the 90-degree position of the knee does not replicate the functional angle of the knee during most sporting activities and certainly not the position of the knee for the mechanism of injury with ACL injuries, and 4) the isometric contraction is not a dynamic motion, therefore, the measure is not a functional movement pattern and only has limited translation to strength beyond the 90-degree position of knee flexion.

Isokinetics has the ability to perform dynamic velocity spectrum testing to sample muscle performance at multiple speeds. Because sporting activities occur during multiple speeds of movement there is a need to assess the muscles involved in multiple ways that can mimic acceleration, deceleration, and speed of movement. Moreover, by testing and strengthening muscles at various speeds, the patient should be better prepared to successfully progress through their rehabilitation program and ultimately RTS. The uniqueness of isokinetics is predicated on the concept of accommodating resistance. As the biomechanics of the joint and the length of the muscle-tendon unit changes throughout the range of motion, the forces will change and isokinetics allows for specificity of testing or rehabilitation by providing accommodation as the range of movement changes. Isokinetic testing allows for dynamic muscle performance testing which has been shown to correlate with functional movements.19–25 Isokinetics have been used for 56 years,26 the first book dedicated to isokinetics was published 40 years ago,27 an entire journal was developed that was dedicated to isokinetics (Isokinetics & Exercise Science) and there have been thousands of articles demonstrating the effectiveness for testing, training, and rehabilitation, with a PubMed search in January of 2024 returning 9,381 articles in Index Medicus journals including isokinetics.

The decline in use of isokinetics noted previously was not solely related to shifting trends in rehabilitation philosophy. The 4 most cited barriers to isokinetics are accessibility, unit size, device complexity and most importantly cost. Not everyone has access to an isokinetic device, generally for the other 3 reasons and they are becoming less and less available. As clinic size has decreased from the once extravagantly large facilities of the 1980’s and 1990’s, the overall footprint of the current large devices are no longer practical. The device systems are terribly complex owing to the attempt to test as many joints and movements as possible, despite the practical clinical need for most of this complexity (Figure 1). Finally, cost has become the driving factor in so many healthcare decisions and the ability to afford an isokinetic testing system is no different. To address all these barriers a prototype isokinetic knee dynamometer system has been developed (Figure 2). This device has a very small footprint, only tests knee extension/flexion, and promises to provide a lower cost method of isokinetic knee testing.

221496 Figure 1. Biodex Isokinetic Dynamometer

221497 Figure 2. Prototype Small BiodexKnee Isokinetic Dynamometer

Isokinetic Testing and Interpretation

Isokinetic testing of the knee flexors and extensors is performed in a seated position using a dynamometer to measure the muscle performance parameters of strength, power, rate of force development, work, and endurance (Figure 3a and 3b). Testing can be performed at multiple angular velocities but is most commonly performed at 180 and 300 degrees/second, as these speeds have been shown to closely approximate functional activity.16,17,28

221498 Figure 3a. Biodex Isokinetic Dynamometer

221499 Figure 3b. Cybex Isokinetic Dynamometer

It is worth mentioning here that one of the persistent criticisms against isokinetics is creating large patellofemoral compression forces and tibial sheer during testing. This is attributable to the early use of testing at 60 degrees/second. Historically, the measurement of peak torque was determined by manually measuring the value on thermal graph paper. Sixty degrees/second was adopted because it was the simplest way to generate a force curve that could be easily measured and interpreted with the testing methods available. Unfortunately, not only is 60 degrees/second not functional or ideal for testing, the practice of using this speed in testing has persisted despite advancements in the computerized software used to assess a test which make the need for manual measurement unnecessary. In Addition, testing at 60 degrees/second produces significantly higher patellofemoral reaction forces and greater anterior tibial translation than the faster speeds of 180 and 300 degrees/second.29 Conversely, speeds beyond 300 degrees/second have been shown to be too fast for many but the highest functioning athlete to be able to “catch” the dynamometer and register values during testing.30

Key isokinetic testing parameters to evaluate include quadriceps torque to body weight ratio at 180 degrees/second, hamstring/quadriceps ratios, bilateral comparisons (Limb Symmetry Index-LSI) of the quadriceps and hamstrings, acceleration rate at 0.2 seconds of knee extension, and endurance values for both the quadriceps and hamstrings musculature. The complete isokinetic testing parameters evaluated and their goals for RTS assessment are outlined in Table 2. While a comprehensive assessment of all parameters and their correlation of other functional testing measures is imperative for an overall picture of the patient as a whole, the testing parameters that have been found to be most beneficial in a battery of test assessments are: T-shuttle run, hop testing, force plate data, and neurocognitive reactive functional testing.

Table 2. Isokinetic Testing criteria

Quadriceps Peak Torques to Body Weight Ratio:

Males 180 deg/sec 60-65%

Females 180 deg/sec 50-55%

Hamstring/Quadriceps Ratio:

Males 180 deg/sec 66-75%

Females 180 deg/sec 75%>

Bilateral Quadriceps Peak Torque Comparison:

Males: 85%>

Females: 85%

Hamstring Bilateral Peak Torque Comparison:

Males: 90%>

Females: 100%>

Acceleration Rates at 0.2 sec

≥ 90% Quadriceps

Endurance Values:

Quadriceps work fatigue ratio 12% decrease or less.

Summary

It is important to perform a battery of tests for pre-participation screening, assessing a patient’s progress through a rehabilitation program, and criterion-based subjective and objective testing protocols for RTS. Isokinetic testing allows for dynamic velocity spectrum testing of multiple muscle groups, although this clinical commentary only focused on knee testing. There is ample research to demonstrate quadriceps deficits last for prolonged periods of time following ACL injuries and after reconstructions. Therefore, it is important to assess the muscle’s performance in each link of the kinetic chain to determine if any isolated weaknesses exist. Despite the limitations of cost and availability isokinetics remains an integral part of the successful formula to assess muscular strength, power, and endurance in an objective manner. Because of the compelling arguments in favor of isokinetics and the need to solve the current re-injury and readiness in return to play issues perhaps the future lies in a dedicated isokinetic knee testing and rehabilitation system.31 This type of dedicated isokinetic knee system may provide the solution to cost effective objective muscle testing. The authors of this article look forward to the future direction of objective muscle assessment, return to play testing, and reducing the incidence of ACL injuries and reinjuries. We feel that isokinetics remains the best method to objectively determine dynamic muscle strength, power, rate of force development, and endurance.
==== Refs
The Need To Change Return to Play Testing in Athletes Following ACL Injury: A Theoretical Model International Journal of Sports Physical Therapy Wilk Kevin E Thomas Zachary M Arrigo Christopher A Davies George J International Journal of Sports Physical Therapy 1 2 2023
18 1 272 281 2159-2896 10.26603/001c.67988 10.26603/001c.67988 36793556
Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study British Journal of Sports Medicine Grindem Hege Snyder-Mackler Lynn Moksnes Håvard Engebretsen Lars Risberg May Arna BMJ 9 5 2016
50 13 804 808 0306-3674 10.1136/bjsports-2016-096031 10.1136/bjsports-2016-096031 27162233
Likelihood of ACL Graft Rupture: Not Meeting Six Clinical Discharge Criteria Before Return to Sport is Associated With A Four Times Greater Risk of Rupture British Journal of Sports Medicine Kyritsis Polyvios Bahr Roald Landreau Philippe Miladi Riadh Witvrouw Erik BMJ 23 5 2016
50 15 946 951 0306-3674 10.1136/bjsports-2015-095908 10.1136/bjsports-2015-095908
A Minority of Athletes Pass Symmetry Criteria in a Series of Hop and Strength Tests Irrespective of Having an ACL Reconstructed Knee or Being Noninjured Sports Health: A Multidisciplinary Approach Markström Jonas L. Naili Josefine E. Häger Charlotte K. SAGE Publications 2023
15 1 45 51 1941-7381 10.1177/19417381221097949 10.1177/19417381221097949 35762123
Young athletes after ACL reconstruction with asymmetric quadriceps strength at the time of return-to-sport clearance demonstrate drop-landing asymmetries two years later The Knee Ithurburn Matthew P. Thomas Staci Paterno Mark V. Schmitt Laura C. Elsevier BV 3 2021
29 520 529 0968-0160 10.1016/j.knee.2021.02.036 10.1016/j.knee.2021.02.036 33756262
Lower Limb Kinetic Asymmetries in Professional Soccer Players With and Without Anterior Cruciate Ligament Reconstruction: Nine Months Is Not Enough Time to Restore “Functional” Symmetry or Return to Performance The American Journal of Sports Medicine Read Paul J. Michael Auliffe Sean Wilson Mathew G. Graham-Smith Philip SAGE Publications 15 4 2020
48 6 1365 1373 0363-5465 10.1177/0363546520912218 10.1177/0363546520912218
Quadriceps Dysfunction Following Joint Preservation Surgery: A Review of the Pathophysiologic Basis and Mitigation Strategies Current Reviews in Musculoskeletal Medicine Cognetti Daniel J. Lynch Thomas B. Rich Elizabeth Bedi Asheesh Dhawan Aman Sheean Andrew J. Springer Science and Business Media LLC 27 5 2023
16 8 338 345 1935-9748 10.1007/s12178-023-09844-0 10.1007/s12178-023-09844-0 37243966
Effect of Quadriceps and Hamstring Strength Relative to Body Weight on Risk of a Second ACL Injury: A Cohort Study of 835 Patients Who Returned to Sport After ACL Reconstruction Orthopaedic Journal of Sports Medicine Simonson Rebecca Piussi Ramana Högberg Johan Senorski Carl Thomeé Roland Samuelsson Kristian Senorski Eric Hamrin SAGE Publications 1 4 2023
11 4 232596712311573 2325-9671 10.1177/23259671231157386 10.1177/23259671231157386 37152619
Return to Sport Activities and Risk of Reinjury Following Primary Anterior Cruciate Ligament Reconstruction Arch Bone Jt Surg Rodriguez-Merchan E.C. Valentino L.A. 2022
10 8 648 660 36258743
Repeat Anterior Cruciate Ligament Injury and Return to Sport in Australian Soccer Players After Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Autograft The American Journal of Sports Medicine Manara Jonathan R. Salmon Lucy J. Kilani Faisal M. Zelaya de Camino Gerardo Monk Claire Sundaraj Keran Pinczewski Leo A. Roe Justin P. SAGE Publications 3 10 2022
50 13 3533 3543 0363-5465 10.1177/03635465221125467 10.1177/03635465221125467
Isokinetic Dynamometer Leg Extensor Peak Torque Measurement: A Time-Delayed Reliability and Score Selection Analysis Study Journal of Functional Morphology and Kinesiology Thompson Brennan J. Xu Jennifer MDPI AG 12 5 2023
8 2 62 2411-5142 10.3390/jfmk8020062 10.3390/jfmk8020062 37218858
Test−Retest Reliability of Isokinetic Ankle, Knee and Hip Strength in Physically Active Adults Using Biodex System 4 Pro Methods and Protocols Tuominen Juho Leppänen Mari Jarske Heidi Pasanen Kati Vasankari Tommi Parkkari Jari MDPI AG 9 3 2023
6 2 26 2409-9279 10.3390/mps6020026 10.3390/mps6020026 36961046
Measurement properties for muscle strength tests following anterior cruciate ligament and/or meniscus injury: What tests to use and where do we need to go? A systematic review with meta-analyses for the OPTIKNEE consensus British Journal of Sports Medicine Urhausen Anouk P Berg Bjørnar Øiestad Britt Elin Whittaker Jackie L Culvenor Adam G Crossley Kay M Juhl Carsten B Risberg May Arna BMJ 16 9 2022
56 24 1422 1431 0306-3674 10.1136/bjsports-2022-105498 10.1136/bjsports-2022-105498
Reliability of isokinetic knee strength measurements in children: A systematic review and meta-analysis PLoS One Muñoz-Bermejo Laura Pérez-Gómez Jorge Manzano Fernando Collado-Mateo Daniel Villafaina Santos Adsuar José C. Public Library of Science (PLoS) 17 12 2019
14 12 e0226274 1932-6203 10.1371/journal.pone.0226274 10.1371/journal.pone.0226274 31846469
The relationship between subjective knee scores, isokinetic testing, and functional testing in the ACL-reconstructed knee Journal of Orthopaedic & Sports Physical Therapy Wilk Kevin E. Romaniello William T. Soscia Susan M. Arrigo Christopher A. Andrews James R. Journal of Orthopaedic & Sports Physical Therapy (JOSPT) 8 1994
20 2 60 73 0190-6011 10.2519/jospt.1994.20.2.60 10.2519/jospt.1994.20.2.60 7920603
Reliability and Validity of Quadriceps Muscle Thickness Measurements in Ultrasonography: A Comparison with Muscle Mass and Strength Progress in Rehabilitation Medicine Ogawa Masato Matsumoto Tsuyoshi Harada Risa Yoshikawa Ryo Ueda Yuya Takamiya Daiki Sakai Yoshitada Japanese Association of Rehabilitation Medicine 2023
8 20230008 2432-1354 10.2490/prm.20230008 10.2490/prm.20230008 36909302
Measurement properties for muscle strength tests following anterior cruciate ligament and/or meniscus injury: What tests to use and where do we need to go? A systematic review with meta-analyses for the OPTIKNEE consensus British Journal of Sports Medicine Urhausen Anouk P Berg Bjørnar Øiestad Britt Elin Whittaker Jackie L Culvenor Adam G Crossley Kay M Juhl Carsten B Risberg May Arna BMJ 16 9 2022
56 24 1422 1431 0306-3674 10.1136/bjsports-2022-105498 10.1136/bjsports-2022-105498
Role of Isokinetic Testing and Training after ACL Injury and Reconstruction ACL Injuries in the Female Athlete Davies George J. Riemann Bryan Ellenbecker Todd Noyes F. R. Barber-Westin S. Springer-Nature 2018
567 588 9783662565575 10.1007/978-3-662-56558-2_24 10.1007/978-3-662-56558-2_24
Analysis of Isokinetic Strength Test in Arthroscopic Meniscus Suture to Improve Knee Joint Strength and Function Altern Ther Health Med Wang S. Guo F. Song X. Zhang Y. Song H. Wu L. Jin J. Dong Q. 2023
29 6 416 424 37384405
The relation-ship between open and closed kinetic chain strength of the lower limb and jumping performance Journal of Orthopaedic & Sports Physical Therapy Blackburn Jonathan R. Morrissey Matthew C. Journal of Orthopaedic & Sports Physical Therapy (JOSPT) 6 1998
27 6 430 435 0190-6011 10.2519/jospt.1998.27.6.430 10.2519/jospt.1998.27.6.430 9617729
Isokinetic knee extension and vertical jumping: are they related? Role of Isokinetic Testing and Training After ACL Injury and Reconstruction Journal of Sports Sciences Iossifidou Anna Baltzopoulos Vasilios Giakas Giannis Informa UK Limited 10 2005
23 10 1121 1127 0264-0414 10.1080/02640410500128189 10.1080/02640410500128189
Young athletes with quadriceps femoris strength asymmetry return to sport after anterior cruciate ligament reconstruction demonstrate asymmetric single-leg drop-landing mechanics The American Journal of Sports Medicine Ithurburn Matthew P. Paterno Mark V. Ford Kevin R. Hewett Timothy E. Schmitt Laura C. SAGE Publications 10 9 2015
43 11 2727 2737 0363-5465 10.1177/0363546515602016 10.1177/0363546515602016
Relationships between isokinetic knee strength, single-sprint performance, and repeated-sprint ability in football players J Strength Cond Res Newman M.A. Tarpenning K.M. Marino F.E. 2004
18 4 867 872 15574095
Assessment of isokinetic knee strength in elite young female basketball players: correlation with vertical jump J Sports Med Phys Fitness Rouis M. Coudrat L. Jaafar H. Filliard Vandewalle JR H Barthelemy Y Driss T. 2015
55 12 1502 1508 25373468
Evaluation of open and closed kinetic chain exercises in rehabilitation following anterior cruciate ligament reconstruction Journal of Physical Therapy Science Uçar Mehmet Koca Irfan Eroglu Mehmet Eroglu Selma Sarp Umit Arik Hasan Onur Yetisgin Alparslan Society of Physical Therapy Science 2014
26 12 1875 1878 0915-5287 10.1589/jpts.26.1875 10.1589/jpts.26.1875 25540486
The isokinetic concept of exercise Physical Therapy Hislop Helen J. Perrine James Oxford University Press (OUP) 1 2 1967
47 1 114 117 0031-9023 10.1093/ptj/47.1.114 10.1093/ptj/47.1.114
A Compendium of Isokinetics in Clinical Usage Davies G.J. S Publishers LaCrosse, WI 1984

Anterior Cruciate Ligament Reconstruction Rehabilitation: A Six-Month Followup of Isokinetic Testing in Recreational Athletes Isokinetics and Exercise Science Wilk Kevin E. Keirns Michael A. Andrews James R. Clancy William G. Arrigo Christopher A. Erber Donna J. IOS Press 1 1 1991
1 1 36 43 1878-5913 10.3233/ies-1991-1107 10.3233/ies-1991-1107
The effects of pad placement and angular velocity on tibial displacement during isokinetic exercise Journal of Orthopaedic & Sports Physical Therapy Wilk Kevin E. Andrews James R. Journal of Orthopaedic & Sports Physical Therapy (JOSPT) 1 1993
17 1 24 30 0190-6011 10.2519/jospt.1993.17.1.24 10.2519/jospt.1993.17.1.24
Anterior cruciate ligament reconstruction rehabilitation: a twelve-week follow-up of isokinetic testing in recreational athletes Isokin Ex Sci Wilk K.E. Andrews J R Arrigo C A Clancy W G Lemak L J Hinger D A Erber D.E. 1992
2 2 82 91
Reliability and Validity of a Novel Isokinetic Knee Dynamometer System Acta of Bioengineering and Biomechanics Riemann Bryan L. Watson Matthew D. Davies George J. Politechnika Wroclawska Oficyna Wydawnicza 2021
23 4 107 11 1509-409X 10.37190/abb-01936-2021-03 10.37190/abb-01936-2021-03
