Previous Article in Journal
Stakeholders’ Perceptions of the Benefits and Barriers to Implementing Environmental Management Systems Within the AECOM Sector in Malaysia
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Standards
Volume 5
Issue 4
10.3390/standards5040030
standards-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Standardization and Utilization of Lower Limb Single Joint Isometric Force Plate Assessments and Recommendations for Future Research

by
Nicholas Ripley
1,*,
Jack Fahey
1,
James Williams
1,
Laura Smith
1,
Steven Ross
1,
Christopher Bramah
1,2 and
Paul Comfort
1,3
1
School of Health and Society, University of Salford, Salford M5 4WT, UK
2
Manchester Institute of Health and Performance, Nuffield Health, Epsom KT18 5AL, UK
3
Strength and Power Research Group, School of Medical and Health Sciences, Edith Cowan University, Joondalup 6027, Australia
*
Author to whom correspondence should be addressed.
Standards 2025, 5(4), 30; https://doi.org/10.3390/standards5040030
Submission received: 24 September 2025 / Revised: 25 October 2025 / Accepted: 4 November 2025 / Published: 5 November 2025
Browse Figures
Review Reports Versions Notes

Abstract

Single joint isometric assessments of force production using force plates have become popular in research and practice; however, there are currently no standardization recommendations. The purpose of the present review was to explore and discuss the use of force plates to assess single joint isometric force production characteristics and provide suggestions on protocol standardization for both laboratory and applied settings. Frequently used single joint isometric assessments currently performed using force plates involve the knee flexors/hip extensors and plantar flexors. Currently there are a range of protocols applied to assessing isometric force production; therefore, we provide recommendations on key methodological features to be considered. We also discuss the potential shortcomings and future research directions for single joint isometric testing in both laboratory and applied settings.

1. Introduction

Force plate technology is becoming increasingly prevalent across a range of professional sectors including sport, health, and tactical. Force plates enable the high-resolution assessment of force–time characteristics relating to Newton’s third law (i.e., every action has an equal and opposite reaction, thus ground reaction force) [1]. Portable force plates are now accessible and used by 50% and 30% of strength and conditioning practitioners in soccer and cricket, respectively [2,3]. Interestingly, the prevalence and use in tactical populations is also increasing [4], with recommendations supporting their use across a range of physical performance assessments for monitoring performance and injury risk. There is currently a gap within the literature supporting the use of force plates within a healthcare setting for older individuals, with some applications in balance and population-specific performance tests (i.e., sit to stand) [5]. However, force plates have frequently been used during the rehabilitation process, including for anterior cruciate ligament (ACL) and hamstring tendon injuries [6,7]. Force plates can be used across a range of dynamic and isometric multi joint and single joint tasks to provide a valid [8], reliable, and accurate assessment of force–time characteristics [9,10], providing a proxy for neuromuscular function (including neuromuscular fatigue) [8]. With the increased availability and affordability of portable force plates, a range of single joint isometric assessments have been developed. These assessments have the specific aim of determining single joint isometric force production characteristics to determine potential injury risk (i.e., identifying the risk of future musculoskeletal injury); identifying training needs (i.e., objectively identifying training priorities [e.g., maximal or rapid force capabilities] or comparing to normative data); and monitoring fatigue (i.e., identifying fatigue profiles and potential mechanisms of fatigue to implement effective protocols for performance restoration) [11,12,13,14,15,16]. Hamstring injuries account for the largest proportion of reported injuries in men’s professional soccer [17] and are consistently elevated across team sports [18]. The hamstrings have an integral role in ACL rehabilitation and they are the most frequently assessed muscle group using single joint isometric assessment [6,7,13,19,20,21], followed by plantar flexors [22,23,24].
Previous reviews have provided practitioners with standardized approaches to performing multi joint assessments. These include guidance on force plate data collection (e.g., joint positions, fixation methods [e.g., straps], weighing period, cueing, and force plate settings such as sampling frequency) and data analysis methods (e.g., metric selection such as force or torque, onset threshold, and the rate of force development [RFD] or the rate of torque development [RTD] calculations) [25,26]. However, currently, no standardized approaches have been suggested for single joint isometric assessments for the lower limb. Therefore, the purpose of this review is to provide details around the standardization requirements for performing single joint isometric assessments using force plates, providing recommendations for data collection, analysis, and metric selection. It is hoped that the standard operating procedures identified within this review can be used by practitioners and researchers to ensure actionable data can be collected. A secondary purpose of this review is to identify gaps within our current knowledge that require investigation.

2. Isometric Hamstring Assessments

Force plate assessments aimed at determining hamstring isometric force production characteristics are currently the most well established within the literature [12,13,20,27,28,29,30,31,32,33]. However, there are a variety of assessment methods that have been suggested to assess the force-generating characteristics of the hamstring, highlighting the need for standardization and standard operating procedures (Table 1). Despite the variety of designs, most tests have been observed to be reliable at measuring peak force (coefficient of variation < 10%, intraclass correlation coefficient > 0.75), with researchers also demonstrating poor–good absolute and relative reliability for measurements of rapid force (e.g., force at 100 ms or RFD) (coefficient of variation > 5%, intraclass correlation coefficient < 0.75) (Table 1) [34,35]. For practitioners to make informed decisions on individuals, reliability should be a key consideration, and acceptable absolute reliability (i.e., coefficient of variation < 10%) is crucial for fatigue monitoring purposes. If substantial measurement variability is present, the identification of true acute change through fatigue becomes less certain, limiting the test’s or metric’s ability to be sensitive to changes in force-generating characteristics [34]. Acceptable relative reliability (intraclass correlation coefficient < 0.75) is essential for assessing chronic changes in performance (i.e., as a result of training), ensuring that the rank order is consistent to be certain a change in performance within a squad or across benchmarks is through the application of a training modality.
Within applied practice, isometric hamstring assessments are utilized for athlete benchmarking and identifying training needs; however, they are more frequently used as a tool to monitor localized muscular fatigue [33]. As strength and fatigue are modifiable risk factors for hamstring strain injuries [36,37], ensuring that isometric hamstring assessments are sensitive to detecting fatigue via monitoring acute changes in peak and rapid force production is crucial. Only a single observation has been made highlighting the risk of future hamstring strain injury from reduced isometric hamstring force using force plates in professional baseball players [12]. However, the authors failed to identify the reliability associated with the test design used and this requires further observation. Across the tests performed, peak force is the most frequently assessed metric when assessing fatigue; however, recently, rapid force is being identified as an additional metric which could be more sensitive to monitoring fatigue at increasing time points (Table 1) [14,33].
It is crucial for practitioners to ensure the appropriate standardization of assessment procedures regardless of the assessment test design (Figure 1). When considering posture during isometric hamstring assessments, five key positions have been identified within the literature, with alterations in hip and knee flexion angles (Table 1). Two of the most frequent assessments (90° of hip and knee flexion [90:90] and 30° of hip and knee flexion [30:30]) have been performed in a supine position, with researchers reporting differences in fixation procedures, including no fixation of the hips [11,27], fixation of the contralateral hip [30,31], or fixation of both hips [20]. To the authors’ knowledge, no study has compared the difference in fixation type. Despite acceptable reliability between all methods, it could be suggested that peak and rapid force could be lower without fixation due to hip extension, while the task is predominantly focused on knee flexion [29,30,31]. Despite no evidence on the effect of fixation on isometric hamstring assessments using force plates, previous work by Alt et al. [38] highlighted that during a prone isokinetic knee flexor assessment, different fixation types have implications on the kinetics of the knee flexor test and importantly should be considered in testing practices.
Three other positions performed while supine have used a fixed immoveable bar in a hip thrust position (40° of hip flexion, knee flexion was not reported [40:NR]; 60° of hip and 75° knee flexion [60:75] and 20° of knee flexion, hip flexion was not reported [NR:20]). Researchers have used a cue for simultaneous hip extension and knee flexion when using these positions; therefore, securing the hips with an immoveable bar is imperative [39,40], which could decrease the ecological validity when testing large groups of athletes. The final position is performed when standing (90° of hip and 20° knee flexion [90:20]); although this removes the necessity for fixation, it does require the use of a wall where support from the wall can be used [20]. No significant difference has been observed in peak force when hands are placed on the wall or the chest [20], with negligible differences in absolute reliability. This highlights that either protocol could be used as long as it is used consistently [20]. However, the 90:20 ratio may result in large individual variability in force production due to mobility requirements; this would consequently impact the length–tension relationship placed upon the hamstrings and the ability to express force [41].
Force–time metrics can be impacted by deviations in equipment, for instance, shoe surface interface (i.e., where the heel of the shoe compresses reducing peak and rapid forces), which becomes an issue with the increasing variety in footwear. It is likely that shoes with increased compression could reduce rapid forces (i.e., RFD, RTD, or force at early time points). Although currently this has not been established within isometric tasks, significant differences have been observed in peak vertical forces in running tasks with different footwear [42]. Similarly, in single joint tasks, cushioning on an isokinetic dynamometer has been found to impact the time to peak velocity and increased the variability in peak torque [43]. To date, there is limited consistency in the use and type of footwear; however, suggestions have recently been made to remove footwear to reduce the effect of this compression on force–time metrics [22]. This may present a viable option; however, when attempting to apply maximal force onto the force plate, this could result in pain-related inhibition, especially in force plates that may have a rough or uneven surface. This would likely reduce the validity of true maximal effort trials which, when using these assessments to monitor changes in an athlete’s performance, could lead to poor training decisions being employed by practitioners (e.g., reduced training load). Future research is required to determine the effect of footwear on peak and rapid force production.
The standardization of verbal cues is seen as a key element of data collection [26,44]. For multi joint assessments, such as the isometric mid-thigh pull (IMTP), a combination cue of “push as hard and fast” has been recommended [26], with an external focus resulting in greater peak forces in comparison to an internal focus [45]. Recently, however, a novel short IMTP protocol has been suggested to assess rapid force production [46,47,48], highlighting that cueing either for rapid force alone (i.e., “push as fast as possible”) or emphasizing rapid force in a combination cue (i.e., “push fast and hard” vs. “push hard and fast”) results in improved absolute and relative reliability for measurements of rapid force and greater early force time characteristics, with reduced maximal force values observed [46,47,48]. These findings are supported within single joint assessments [44,49], highlighting the need for bespoke cues when observing maximal or rapid force characteristics. Therefore, practitioners and researchers need to determine which metrics they want to observe: if maximal force is of interest, then a combination cue should be used; however if rapid force is of interest, a cue emphasizing speed (either single cue or a combination cue) will be required. Due to the different test designs in isometric hamstring assessments (Table 1), cueing could impact the force vector application. The 90:90, 30:30, 40:NR, NR:20, and 60:75 assessment should primarily be vertical only, especially when cueing for knee flexion and when participants are fixed at the hip. However, the 90:20 assessment can be impacted via the cue used in the design, which can allow for both knee flexion and hip extension, potentially resulting in a vertical and/or horizontal vector [13]. Rasp et al. [13,50] compared either a vertical-only cue to a combined vertical–horizontal cue (i.e., “exert maximal force vertically into the plate” vs. “exert maximal force vertically into the plate and pull the plate to you”). The authors observed a significant and large effect on the force–time metrics, with the vertical-only cue resulting in greater vertical forces (Fz). However, it did miss anterior–posterior horizontal forces (Fx) to a large magnitude, potentially highlighting a lack of accuracy [13,50]. However, it is important to consider that many practitioners only have access to uniaxial force plates, which only assess vertical force production, which may negate some of the aspects identified by Rasp and colleagues [13]. Further research is required to investigate the use of different cues in isometric hamstring assessments (rapid vs. maximal, knee flexion vs. hip extension, or vertical vs. horizontal).
Table 1. Isometric hamstring designs’ associated reliability and sensitivity for detecting fatigue.
Table 1. Isometric hamstring designs’ associated reliability and sensitivity for detecting fatigue.
Test DesignMetric (Units)Absolute ReliabilityRelative ReliabilityReferenceMetric (Units)Post+24 h+48 h+72 hReference
90:90Peak force (N)✓✓[27,28,29,30,31]Peak force (N)✓?✓x[20,31,51]
Force 100 ms (N)✓✓
Force 200 ms (N)✓✓
RFD 0–100 ms (N/s)✓x
RFD 0–200 ms (N/s)✓x
30:30Peak force (N)✓✓[31,33]Peak force (N)✓✓xx[30,31,33,52]
RFD 50–100 ms (N/s)x✓RFD 50–100 ms (N/s)✓???[33]
RFD 100–150 ms (N/s)x✓RFD 100–150 ms (N/s)✓???
90:20Peak force (N)✓✓[13,14,20]Peak force (N)✓?✓x[20]
Peak torque (N⋅m)✓✓
RFD 0–50 ms (N/s)?✓Peak torque (N⋅m)✓✓✓x[14]
RTD 0–50 ms (N⋅m/s)✓✓✓✓
RFD 0–100 ms (N/s)?✓
RFD 100–200 ms (N/s)?✓RTD 0–100 ms (N⋅m/s)✓✓✓✓
Peak RFD (N/s)?✓
RTD 0–50 ms (N⋅m/s)✓✓RTD 0–250 ms (N⋅m/s)✓✓✓x
RTD 0–100 ms (N⋅m/s)✓✓
RTD 0–250 ms (N⋅m/s)✓✓Peak RTD (N⋅m/s)xxxx
Peak RTD (N⋅m/s)✓✓
40:NRPeak force (N)✓✓[40]N/AN/AN/A
Peak torque (N⋅m)✓✓
Torque 150 ms (N⋅m)xx
60:75Peak torque (N⋅m)?✓[39]N/AN/AN/A
NR:20Peak force (N)N/AN/A[12]N/AN/AN/A
✓ = acceptable reliability (e.g., CV < 10%, ICC > 0.75) and sensitive to fatigue; ? = no evidence to support reliability or sensitivity; x = unacceptable reliability or not sensitive to fatigue. Abbreviations: 90:90 = 90° degrees of hip and knee flexion; 30:30 = 30° degrees of hip and knee flexion; 90:20 = 90° degrees of hip and 20° knee flexion; 40:NR = 40° degrees of hip and not reported knee flexion; 60:75 = 60° degrees of hip and 75° knee flexion; NR:20 = hip not reported and 20° knee flexion; RFD = rate of force development; RTD = rate of torque development; N/A = not applicable due to lack of evidence.
The collection of accurate and reliable data requires the force plates to be appropriately set up. Two key aspects of the data collection include sampling frequency and onset threshold [28,53,54,55]. Within the 90:90 assessment, higher sampling frequencies (>1000 Hz) have lower reliability for measurements of rapid force, with a minimal effect on peak force [28]. This highlights the fact that if practitioners are interested in rapid force measurements, and monitoring changes over time, they should select an appropriate sampling frequency. However, not all commercially available force plate companies allow practitioners to select their own sampling frequency; therefore, this should be accounted for when practitioners are selecting metrics and force plate companies could look to add this as an option. Interestingly, however, much of the research, even at higher sampling frequencies (i.e., 1000 Hz), still enables the reliable collection of rapid force metrics [28]. A defined onset threshold is the minimum value that identifies the onset of contraction (e.g., the ground reaction force must exceed this value before any calculations are made). The onset threshold used impacts’ time-related force metrics (i.e., RFD, force at early time points) in addition to the reliability observed for rapid force metrics in the 90:90 assessment [55]. Practitioners and researchers should consider the onset threshold used in relation to the metrics of interest. Comparable to the IMTP, an onset threshold relative to system weight (i.e., limb weight) from a one second weighing period was the most reliable and possessed the greatest rapid force measurements [53,55,56]. Therefore, practitioners are recommended to use a threshold of five standard deviations of the one second weighing period, when rapid force measurements are of interest, and use this threshold consistently within a club’s standard operating procedure. If system weight cannot be accurately identified, for instance with lower segmental system weights (i.e., youth athletes), especially within automated systems, a known load could be added to the force plate to artificially increase this system weight for accurate onset identification for rapid force measurements, once the known weight has been subtracted from the system weight.
Peak force is the most frequently reported metric within isometric hamstring assessments [11,13,19,20,27,28,29,30,31,32,33]; however, recent suggestions have highlighted the utility of observing rapid force metrics [11,27,29]. Peak force is sensitive to fatigue across the three testing protocols assessed, with the 90:20 assessment appearing to have a prolonged sensitivity, likely due to the increased muscle length (Table 1). Currently, only RFD during the 30:30 assessment has been assessed post match and shown to be sensitive to fatigue, which was to a greater magnitude than peak force [33,57], potentially highlighting a greater sensitivity to fatigue. Calculating torque has only been performed within the 90:20 assessment, as per recommendations from Rasp et al. [13]. Unsurprisingly, peak torque showed a similar fatigue profile to peak force [14]. Early RTD (0–50 ms and 0–100 ms and normalized RTD, where RTD is normalized to peak torque) showed increased sensitivity following a fatiguing activity, with decreases observed for up to 72 h [14]. Later, RTD (i.e., 0–250 ms) returned to baseline 72 h post fatiguing activity, while peak RTD was not sensitive to fatigue at any time point. These results collectively highlight that force at early time points and RFD or RTD over shorter epochs demonstrate increased sensitivity to fatigue in comparison to peak values or later time points. However, future research should look to determine RFD or force at early time points in all test positions for up to 72 h following fatiguing activity, as there is a clear gap within the literature for this. Furthermore, while calculating torque or RTD may marginally improve sensitivity to fatigue, calculating torque could have limited ecological validity within practice due to the increased need to calculate torque. However, currently, further work is required to validate the potential of increased sensitivity from RTD and rapid force production, as it is currently limited to observations within two studies using the same test design (90:20) [13,14].

3. Isometric Plantar Flexor Testing

Force plates have also been used to assess isometric plantar flexor force-generating characteristics [22,23,24]. Four primary test designs have been suggested to assess isometric plantar flexor strength, specifically standing, seated, kneeling, and using a custom leg press device (Table 2). The difference in test positions has been designed to reflect the biarticular nature of the gastrocnemius, with bent knee positions (i.e., seated and kneeling) placing the gastrocnemius into passive insufficiency, whereby the muscle–tendon unit length is at a suboptimal length to produce force [58]. Interestingly, however, the muscle activation of the gastrocnemius (medialis and lateralis) is optimized when the ankle is in neutral–slight dorsiflexion (85–90° ankle angle), with knee flexion between 130 and 150° [58]. Contrastingly, there is no difference in soleus muscle activation, with the greatest activation occurring at 90° at the ankle and 110° at the knee [58]. These findings potentially highlight the utility of bent knee variations to attain a greater understanding of the force-generating characteristics of the gastrocnemius and soleus. However, the muscle activation between different test positions is currently a clear gap in the literature that requires investigation and how this information could be effective for practitioners is unknown but likely could contribute to the prescription of training and rehabilitation.
Despite the tests being isometric, due to the tension placed upon the Achilles tendon and the rotation of the ankle and knee joint during the isometric action, there will be movement into plantar flexion of between 10 and 20° [58]. Therefore, when positioning athletes in these tests, they need to be securely fixed into position; this means that the use of foam pads should be eliminated due to the cushioning reducing isometric force metrics. McMahon and colleagues [22] used solid rubber to “jam” athletes into position, while also removing all footwear to reduce all cushioning, thereby minimizing any joint movement due to compression. However, this is not consistent across the literature with Rhodes et al. [59] using an Airex pad to cushion participants’ thighs, which would likely impact the force outcome, especially rapid force production. O’Neil et al. [60] attempted to overcome this by using a fixed strap-based system to assess seated plantar flexor strength; despite its reliability and small clinically insignificant bias, it could be expected that strap fatigue could impact this test design overtime. With regard to utility, using the IMTP or isometric squat rig within the standing and kneeling planter flexor assessments supports the ecological validity of these tests within practice. Moreover, the kneeling assessment enables individual standardized heights for the knee angle joint positions which may be harder to achieve within the seated variation, for which different populations may need different seated heights (although the strap-based system could overcome this issue [60]). McMahon et al. [22] supports the utility of the kneeling isometric plantar flexor assessment, taking on average 1 min 58 s to set up and 1 min 16 s to perform the test on each limb within a team sport environment. The leg press variation likely has the lowest ecological validity of all performance assessments, which is largely due to the difficulties of mounting the force plates onto a leg press device and the substantial variation in leg press design [61,62].
Table 2. Isometric plantar flexor designs and current observations.
Table 2. Isometric plantar flexor designs and current observations.
StandingSeatedKneelingLeg Press
Knee angle (°)170–180°90°N/R180°
Ankle angle (°)130° PF90-100° PF20° DF90° PF
Absolute reliability✓✓✓✓
Relative reliability✓✓✓✓
Reference[24][24,60,63][22][61,62]
PF = plantar flexion; DF = dorsi flexion; ✓ = acceptable absolute and relative reliability (e.g., CV < 10%, ICC > 0.75).
Two sampling frequencies have been used when assessing isometric plantar flexor force characteristics using force plates: a high frequency of 1000 Hz [22,24] and a lower frequency of 100 Hz [15,60]. Although several researchers have failed to report the sample frequency [61,62,64], higher sampling frequencies are likely to be optimized when the full system weight is on the force plate (e.g., standing plantar flexor assessment [i.e., full mass is on the force plate]), which would be consistent with multi joint tasks such as the IMTP [54]. Lower sampling frequencies could be the result of more affordable technology [15,60], but it could also be recommended with assessments that have a lower system weight such as in the seated, kneeling, and leg press designs, where there is only the shank and thigh mass or the weight of the leg press apparatus (dependent on equipment design). The greater system weight would increase the precision of the identification of the force onset, improving the reliability and accuracy of rapid force measurements [28]. Recently, authors have shown that within the isometric hamstring assessment (i.e., low system weight), lower sampling frequencies improved the reliability of rapid force measurements [28]; although, if the frequency is too low the precision of rapid force metrics can be compromised.
Between the variations there are large differences in system weight, with the standing plantar flexor design having the greatest system weight in comparison to the seated and leg press designs. This is an important consideration if practitioners are considering comparing between the variations where the gastrocnemius is at an optimal length versus a suboptimal length (e.g., standing vs. kneeling). Therefore, practitioners need to be aware of the differences in system weight and be able to appropriately collect this information (i.e., one second stable weighing period) to determine net peak force (i.e., force produced is greater than system weight), as gross peak force which includes system weight mass would mask any differences in plantar flexor peak force between positions. Currently, only maximal force generating has been observed within the isometric plantar flexor assessments when using force plates, hence cueing has been performed to match this (i.e., “performing maximal contraction”, “hard and fast”) [44]. A single study has observed force at early time points [64], although the cueing for this study was unclear and could lack validity to observe rapid measurements. This highlights a clear gap in the literature for future research to observe rapid force metrics (e.g., RFD or force at early time points). This could be crucial in monitoring changes in performance through fatigue and/or progression through a rehabilitation process (e.g., reintroduction to plyometrics). The plantar flexor muscle tendon unit is primarily used in stretch shortening cycle actions, such as during sprinting (>7 m/s), where the soleus is required to produce peak forces up to 8.7 ± 0.83 × body mass in 0.15 ± 0.01 s [65]. The limited number of metrics observed also likely explains why the utilization of the force plate isometric assessments has only primarily been for benchmarking and training monitoring purposes [15,61,62,64]. This is despite the utility of the isometric plantar flexor to monitor fatigue or acute changes in performance using both peak and maximal force and its potential to be performed as part of clinical assessment within rehabilitation [66], especially when considering the reactions in soleus force-generating capability [66]. Therefore, future research should look at the feasibility at employing isometric plantar flexor assessments within a clinical rehabilitation setting for monitoring and its potential to provide clear thresholds for progression.

4. Discussion

The findings of this review highlight the increasing utility of single joint isometric assessments within sport. Moreover, as practitioners are gaining increased accessibility to force plate technology within sport [2,3], it is important to acknowledge the methods and procedures that enable accurate, reliable, and actionable data collection within the methods themselves. It is also integral to ensure that the appropriate standardization of force plate protocols is applied, and applied consistently by all practitioners within that environment, as changes could also affect the outcome values, resultant interpretation, and interventions. Therefore, this requires practitioners, researchers, and high-performance departments to follow robust standard operating procedures to ensure actionable data can be collected when using force plates within single joint isometric assessments. It is also recommended that organizations (i.e., sports teams/organizations) use the standard operating procedures and establish their own population-specific reliability to enable the selection of appropriate metrics to determine meaningful changes in the performance of single joint isometric assessments.
As with any technology, we want to reduce the amount of noise present within the signal [67]. To accomplish this with force plates, there are several key aspects that need attention, specifically the surface, zeroing, filtering and smoothing the data. It is crucial to consider the surface the force plates are being placed on when force plate testing, making sure the force plate is placed on a flat, stable, solid surface [68]. Although, for isometric tasks, this is less of an issue with regard to the differences in impact forces from different surfaces, which may be experienced within jumping tasks [69]. An unstable surface could result in errors within onset identification, due to increased variability within the weighing period, which could impact measurements of rapid force, which have shown increased sensitivity to fatigue (Table 1). Similarly, it should be ensured that the force plate is level; if not accounted for, the vertical force could be resolved into horizontal components, thus affecting the measured vertical force. This is particularly pertinent for uniaxial force plates which do not allow for the measurement of horizontal force contributions.
Zeroing force plates is also an integral process that needs to be followed to reduce the signal noise. The timing of zeroing force plate technology is scarcely reported within research [8]. If zeroing is not routinely performed, for instance when moving the force plate or between participants, this can lead to integration drift in the signal, resulting in erroneous data. This is potentially problematic within single joint isometric assessments, where the change in output over time negatively impacts the scaled quantity of maximal or rapid force production (i.e., relative peak force [N/kg] or relative force at 100 ms), impacting the accuracy of the measurement [8].
When acquiring data, as highlighted within the isometric hamstring, sampling frequency is a key consideration in acquiring reliable data [28]. Ensuring the correct sampling frequency is integral to the process for minimizing noise. Previous work has established that sampling frequency has meaningful effects on dynamic tasks [70], specifically impacting time-related variables such as RFD. The sampling frequency should be twice the signal of interest [71,72], highlighting that for dynamic tasks a higher sampling frequency is required (e.g., recommended sampling frequency for CMJ 1000 Hz [73,74]). Therefore, for isometric assessments a lower sampling frequency could be used; however, practitioners should ensure that the sampling frequency does not impact the collection and precision of rapid force characteristics (i.e., force at 100 ms and RFD 0–100 ms, etc.). Dos’Santos and colleagues [54] recommended a minimum sampling frequency of 500 Hz for the IMTP, which could be recommended for the single joint assessments presented within the present study; however, further research is required. Not all force plate manufacturers allow the practitioner to select their own sampling frequency, with some manufacturers having a fixed sampling rate (e.g., 1000 Hz). Therefore, practitioners need to be acutely aware of the type of force plate they are using and, if they change the force plate’s settings, acknowledge how the change in sampling frequency could impact the results. Hence, standard operating procedures should be introduced at departmental and institutional levels to ensure the consistency and accuracy of reporting.
Filtering the acquired signal can enhance the observed results by reducing the noise within the signal and is commonly recommended [75]. For the IMTP, low pass filtering has been shown to have a meaningful effect on peak and rapid force production [76], with the authors recommending that researchers and practitioners have standardized filtering procedures crucial for longitudinal monitoring and when comparing data to previous data. Across force plate technologies, different filtering is applied, with standardized filters (e.g., 50 Hz low pass filter); however, there are slight differences in the identification of dynamic tasks because of different filtering techniques [9]. However, as single joint isometric assessments have minimal movement and any associated error could be because of over sampling with a low system weight, it should be re-enforced that researchers and practitioners should utilize standardized filtering procedures [76] or, at a minimum, practitioners should make themselves aware of their default force plate filter frequencies and how or why these may be changed, to ensure that changes in any single joint force plate characteristics are meaningful changes and not through errors within data analysis.

5. Conclusions and Future Directions

The present review provides researchers and practitioners with guidance on the implementation of single joint isometric force plate assessments for both the hamstrings and plantar flexors in both sport and clinical settings [6,7,30]. Although normative data is scarce from using the tests described within the present study, recent work has established normative data for professional soccer players for the 90:90 and 30:30 isometric hamstrings assessments [16]. When peak forces are ratio-scaled to body mass, only trivial differences were observed between positional groups, with 3.96–4.84 N·kg1 and 4.09–4.98 N·kg1 being determined as the average for the 30:30 and 90:90 isometric hamstring assessments, respectively [16], with an average between limb difference of 5.5%. Practitioners should look for differences >6% to be considered meaningful within isometric hamstring assessments [16]. To date, only a single study has been published on normative data for plantar flexor assessments [15]. Lee et al. [15] highlighted, within professional rugby union players, an average force during seated isometric plantar flexion of 1.86 × body weight, with backs (2.00 × body weight) having a greater relative strength than forwards (1.75 × body weight). Practitioners could use the normative data presented to inform training and rehabilitation; however, further work is needed to establish normative values from the other designed test described within the present review across populations, including general and tactical populations for performance and rehabilitation purposes [77].
Both the hamstring and plantar flexor assessments could be used to monitor changes in force characteristics through either fatigue or the implementation of training (including rehabilitation). For the assessments to be used effectively and accurately, standard operating procedures should be critically developed by practitioners to ensure that robust protocols are based on their own considerations (e.g., technology availability with financial implications and time requirement). However, due to the variability and current scarcity of research within the test designs, there are a series of key considerations that need to be acknowledged by practitioners for both isometric hamstring (Figure 1) and isometric plantar flexor (Figure 2) assessments to develop their standard operating procedures.
The development of standard operating procedures using the considerations identified should give practitioners confidence in selecting and performing appropriate methods to collect data effectively and accurately. The consistent application of standard operating procedures enables any data that is collected to be used in practice to monitor changes in performance through fatigue or adaptations from training, ensuring practitioners can make informed decisions on training. However, as highlighted throughout this review, there are several areas that still need observing in the literature to understand their effectiveness to be used in practice. Therefore, the information identified within Table 3 provides recommendations for future research on single joint isometric assessments using force plates. We hope this provides clear guidance on where gaps currently exist within the literature that should be researched in the future.

Author Contributions

Conceptualization, N.R. and J.F.; investigation, N.R., J.F. and J.W.; writing—original draft preparation, N.R. and J.F.; writing—review and editing, N.R., J.F., C.B., L.S., J.W., S.R. and P.C.; visualization, N.R. and J.F. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Linthorne, N. Analysis of standing vertical jumps using a force platform. Am. J. Phys. 2001, 69, 1198–1204. [Google Scholar] [CrossRef]
  2. Weldon, A.; Duncan, M.J.; Turner, A.; Christie, C.J.; Pang, C.M.C. Contemporary practices of strength and conditioning coaches in professional cricket. Int. J. Sports Sci. Coach. 2020, 16, 585–600. [Google Scholar] [CrossRef]
  3. Weldon, A.; Duncan, M.J.; Turner, A.; Sampaio, J.; Noon, M.; Wong, D.P.; Lai, V.W. Contemporary practices of strength and conditioning coaches in professional soccer. Biol. Sport 2020, 38, 377–390. [Google Scholar] [CrossRef] [PubMed]
  4. Merrigan, J.J.; Stone, J.D.; Martin, J.R.; Hornsby, W.G.; Galster, S.M.; Hagen, J.A. Applying Force Plate Technology to Inform Human Performance Programming in Tactical Populations. Appl. Sci. 2021, 11, 6538. [Google Scholar] [CrossRef]
  5. Hellmers, S.; Fudickar, S.; Lau, S.; Elgert, L.; Diekmann, R.; Bauer, J.M.; Hein, A. Measurement of the Chair Rise Performance of Older People Based on Force Plates and IMUs. Sensors 2019, 19, 1370. [Google Scholar] [CrossRef]
  6. Taberner, M.; Cohen, D.D. Physical preparation of the football player with an intramuscular hamstring tendon tear—Clinical perspective with video demonstrations. Br. J. Sports Med. 2018, 52, 1275–1278. [Google Scholar] [CrossRef]
  7. Taberner, M.; van Dyk, N.; Allen, T.; Neil, J.; Richter, C.; Drust, B.; Betancur, E.; Cohen, D.D. Physical preparation and return to performance of an elite female football player following ACL reconstruction: A journey to the FIFA Women’s World Cup. BMJ Open Sport Exerc. Med. 2020, 6, e000843. [Google Scholar] [CrossRef] [PubMed]
  8. Badby, A.J.; Ripley, N.J.; McMahon, J.J.; Mundy, P.; Comfort, P. Scoping review of methods of monitoring acute changes in lower body neuromuscular function via force plates. PLoS ONE 2025, 20, e0322820. [Google Scholar] [CrossRef]
  9. Merrigan, J.J.; Stone, J.D.; Galster, S.M.; Hagen, J.A. Analyzing Force-Time Curves: Comparison of Commercially Available Automated Software and Custom MATLAB Analyses. J. Strength Cond. Res. 2022, 36, 2387–2402. [Google Scholar] [CrossRef]
  10. Merrigan, J.J.; Stone, J.D.; Hornsby, W.G.; Hagen, J.A. Identifying Reliable and Relatable Force–Time Metrics in Athletes—Considerations for the Isometric Mid-Thigh Pull and Countermovement Jump. Sports 2020, 9, 4. [Google Scholar] [CrossRef]
  11. Barber, R.; Fahey, J.T.; Comfort, P.; Ripley, N.J. Normalization of rapid force to peak force in an isometric hamstring assessment using force plates. Apunt. Sports Med. 2024, 59, 100450. [Google Scholar] [CrossRef]
  12. Driggers, A.R.; Fry, A.C.; Chochrane-Snyman, K.C.; Wagle, J.P.; McBride, J.M. Effectiveness of Single Leg Isometric Bridge and Nordic Hamstring Exercise Testing for Prediction of Hamstring Injury Risk in Professional Baseball Players. Am. J. Sports Med. 2025, 53, 1–9. [Google Scholar] [CrossRef]
  13. Rasp, D.M.; Paternoster, F.K.; Kern, J.; Schwirtz, A. Precise instruction and consideration of the vertical and horizontal force component increases validity and reliability of the 90:20 Isometric Posterior Chain Test. PLoS ONE 2024, 19, e0312843. [Google Scholar] [CrossRef]
  14. Cosio, P.L.; Moreno-Simonet, L.; Fernández, D.; Lloret, M.; Padulles, X.; Padulles, J.M.; Farran-Codina, A.; Rodas, G.; Cadefau, J.A. Football (soccer) match-derived hamstring muscles residual fatigue can be monitored using early rate of torque development. Eur. J. Appl. Physiol. 2025, 125, 1449–1461. [Google Scholar] [CrossRef]
  15. Lee, M.; Lancaster, M.; Tulloch, L.; O’Leary, B.; Power, E.; Howes, D.; Sourbuts, B.; Berry, A.; Maher, F.; O’Neill, S. Normative isometric plantarflexion strength values for professional level, male rugby union athletes. Phys. Ther. Sport 2023, 61, 114–121. [Google Scholar] [CrossRef]
  16. Ripley, N.J.; Fahey, J.T.; Comfort, P.; McMahon, J.J.; Jones, P.A.; Bramah, C. Normative Single Joint Isometric Hamstring Strength Scores From Professional Soccer Players During Preseason. J. Strength Cond. Res. 2025, 39, e1329–e1336. [Google Scholar] [CrossRef] [PubMed]
  17. Ekstrand, J.; Bengtsson, H.; Waldén, M.; Davison, M.; Khan, K.M.; Hägglund, M. Hamstring injury rates have increased during recent seasons and now constitute 24% of all injuries in men’s professional football: The UEFA Elite Club Injury Study from 2001/02 to 2021/22. Br. J. Sports Med. 2023, 57, 292–298. [Google Scholar] [CrossRef] [PubMed]
  18. Maniar, N.; Carmichael, D.S.; Hickey, J.T.; Timmins, R.G.; San Jose, A.J.; Dickson, J.; Opar, D. Incidence and prevalence of hamstring injuries in field-based team sports: A systematic review and meta-analysis of 5952 injuries from over 7 million exposure hours. Br. J. Sports Med. 2023, 57, 109–116. [Google Scholar] [CrossRef]
  19. Cuthbert, M.; Comfort, P.; Ripley, N.; McMahon, J.J.; Evans, M.; Bishop, C. Unilateral vs. bilateral hamstring strength assessments: Comparing reliability and inter-limb asymmetries in female soccer players. J. Sports Sci. 2021, 39, 1481–1488. [Google Scholar] [CrossRef] [PubMed]
  20. Matinlauri, A.; Alcaraz, P.E.; Freitas, T.T.; Mendiguchia, J.; Abedin-Maghanaki, A.; Castillo, A.; Martinez-Ruiz, E.; Carlos-Vivas, J.; Cohen, D.D. A comparison of the isometric force fatigue-recovery profile in two posterior chain lower limb tests following simulated soccer competition. PLoS ONE 2019, 14, e0206561. [Google Scholar] [CrossRef]
  21. Knezevic, O.M.; Mirkov, D.M.; Kadija, M.; Milovanovic, D.; Jaric, S. Evaluation of Isokinetic and Isometric Strength Measures for Monitoring Muscle Function Recovery After Anterior Cruciate Ligament Reconstruction. J. Strength Cond. Res. 2014, 28, 1722–1731. [Google Scholar] [CrossRef]
  22. McMahon, J.J.; Ripley, N.J.; Comfort, P.; Robles-Palazon, F.J.; Fahey, J.T.; Badby, A.J.; Bramah, C. The Kneeling Isometric Plantar Flexor Test: Preliminary Reliability and Feasibility in Professional Youth Football. J. Funct. Morphol. Kinesiol. 2023, 8, 164. [Google Scholar] [CrossRef] [PubMed]
  23. Mattiussi, A.M.; Shaw, J.S.; Price, P.; Brown, D.B.; Cohen, D.D.; Lineham, J.; Pedlar, C.R.; Tallent, J.; Atack, A. The association of range of motion, lower limb strength, and load during jump landings in professional ballet dancers. J. Biomech. 2024, 168, 112119. [Google Scholar] [CrossRef]
  24. Mattiussi, A.M.; Shaw, J.W.; Cohen, D.D.; Price, P.; Brown, D.D.; Pedlar, C.R.; Tallent, J. Reliability, variability, and minimal detectable change of bilateral and unilateral lower extremity isometric force tests. J. Sport Exerc. Sci. 2022, 6, 191–199. [Google Scholar] [CrossRef]
  25. Bishop, C.; Turner, A.; Jordan, M.; Harry, J.; Loturco, I.; Lake, J.; Comfort, P. A Framework to Guide Practitioners for Selecting Metrics During the Countermovement and Drop Jump Tests. Strength Cond. J. 2022, 44, 95–103. [Google Scholar] [CrossRef]
  26. Comfort, P.; Dos’Santos, T.; Beckham, G.K.; Stone, M.; Guppy, S.; Haff, G. Standardization and Methodological Considerations for the Isometric Midthigh Pull. Strength Cond. J. 2019, 41, 57–79. [Google Scholar] [CrossRef]
  27. Ripley, N.; Fahey, J.T.; Cuthbert, M.; McMahon, J.; Comfort, P. Rapid force generation during unilateral isometric hamstring assessment: Reliability and relationship to maximal force. Sports Biomech. 2023, 1–12. [Google Scholar] [CrossRef]
  28. Ripley, N.; McMahon, J.J.; Comfort, P. Effect of sampling frequency on a unilateral isometric hamstring strength assessment using force plates. J. Sci. Sport Exerc. 2024, 1–9. [Google Scholar] [CrossRef]
  29. Ripley, N.J.; Barber, R.; Fahey, J.T.; Comfort, P. Early Versus Late Rapid Force Production During Single-Joint Isometric Hamstring Assessment Using Force Plates. J. Strength Cond. Res. 2024, 38, 2074–2078. [Google Scholar] [CrossRef]
  30. Constantine, E.; Taberner, M.; Richter, C.; Willett, M.; Cohen, D.D. Isometric Posterior Chain Peak Force Recovery Response Following Match-Play in Elite Youth Soccer Players: Associations with Relative Posterior Chain Strength. Sports 2019, 7, 218. [Google Scholar] [CrossRef]
  31. McCall, A.; Nedelec, M.; Carling, C.; Le Gall, F.; Berthoin, S.; Dupont, G. Reliability and sensitivity of a simple isometric posterior lower limb muscle test in professional football players. J. Sports Sci. 2015, 33, 1298–1304. [Google Scholar] [CrossRef]
  32. Moreno-Perez, V.; Mendez-Villanueva, A.; Soler, A.; Del Coso, J.; Courel-Ibanez, J. No relationship between the nordic hamstring and two different isometric strength tests to assess hamstring muscle strength in professional soccer players. Phys. Ther. Sport 2020, 46, 97–103. [Google Scholar] [CrossRef]
  33. Bettariga, F.; Bishop, C.; Martorelli, L.; Turner, A.; Lazzarini, S.G.; Algeri, C.; Maestroni, L. Acute Effects of a Fatiguing Protocol on Peak Force and Rate of Force Development of the Hamstring Muscles in Soccer Players. J. Sci. Sport Exerc. 2024, 7, 177–185. [Google Scholar] [CrossRef]
  34. Hopkins, W. Measures of Reliability in Sports Medicine and Science Measurement Error & Reliability. Sports Med. 2000, 30, 1–15. [Google Scholar]
  35. Koo, T.K.; Li, M.Y. A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research. J. Chiropr. Med. 2016, 15, 155–163. [Google Scholar] [CrossRef] [PubMed]
  36. Green, B.; Bourne, M.; van Dyk, N.; Pizzari, T. Recalibrating the risk of hamstring strain injury (HSI)—A 2020 systematic review and meta-analysis of risk factors for index and recurrent HSI in sport. Br. J. Sports Med. 2020, 54, 1081–1088. [Google Scholar] [CrossRef] [PubMed]
  37. Green, B.; Bourne, M.N.; Pizzari, T. Isokinetic strength assessment offers limited predictive validity for detecting risk of future hamstring strain in sport: A systematic review and meta-analysis. Br. J. Sports Med. 2018, 52, 329–336. [Google Scholar] [CrossRef]
  38. Alt, T.; Etzel, J.P.; Knicker, A.J.; Strüder, H.K. The effects of fixation and contraction mode on prone isokinetic knee flexor tests. Isokinet. Exerc. Sci. 2019, 27, 143–151. [Google Scholar] [CrossRef]
  39. Wild, J.J.; Bezodis, I.N.; North, J.S.; Bezodis, N.E. Characterising initial sprint acceleration strategies using a whole-body kinematics approach. J. Sport Sci. 2022, 40, 203–214. [Google Scholar] [CrossRef]
  40. Goodwin, J.E.; Bull, A.M. Novel Assessment of Isometric Hip Extensor Function: Reliability, Joint Angle Sensitivity, and Concurrent Validity. J. Strength Cond. Res. 2022, 36, 2762–2770. [Google Scholar] [CrossRef]
  41. Kellis, E.; Blazevich, A.J. Hamstrings force-length relationships and their implications for angle-specific joint torques: A narrative review. BMC Sports Sci. Med. Rehabil. 2022, 14, 1–34. [Google Scholar] [CrossRef]
  42. Logan, S.; Hunter, I.; Ty Hopkins, J.; Feland, B.; Parcell, A.C. Ground reaction force differences between running shoes, racing flats, and distance spikes in runners. J. Sport Sci. Med. 2010, 9, 147–153. [Google Scholar]
  43. Ling, W.; Chen, F.C.; McDonough, A.L. Evaluation of the Cushion Setting on Performance of a Biodex II Dynamometer. Arch. Phys. Med. Rehabil. 1999, 80, 350–354. [Google Scholar] [CrossRef] [PubMed]
  44. Maffiuletti, N.A.; Aagaard, P.; Blazevich, A.J.; Folland, J.; Tillin, N.A.; Duchateau, J. Rate of force development: Physiological and methodological considerations. Eur. J. Appl. Physiol. 2016, 116, 1091–1116. [Google Scholar] [CrossRef]
  45. Halperin, I.; Williams, K.J.; Martin, D.T.; Chapman, D.W. The Effects of Attentional Focusing Intructions on Force Production During Isometric Midthigh Pull. J. Strength Cond. Res. 2016, 30, 919–923. [Google Scholar] [CrossRef] [PubMed]
  46. McCormick, B.J.; MacMahon, C.; Talpey, S.W.; James, L.P. The Influence of Instruction on Isometric Mid-Thigh Pull Force-Time Variables. Int. J. Strength Cond. 2022, 2, 1–9. [Google Scholar] [CrossRef]
  47. Guppy, S.; Kotani, Y.; Brady, C.J.; Connolly, S.; Comfort, P.; Haff, G.G. The Reliability and Magnitude of Time-Dependent Force-Time Characteristics During the Isometric Midthigh Pull Are Affected by Both Testing Protocol and Analysis Choices. J. Strength Cond. Res. 2022, 36, 1191–1199. [Google Scholar] [CrossRef]
  48. Suarez, D.G.; Carroll, K.M.; Slaton, J.A.; Rochau, K.G.; Davis, M.W.; Stone, M.H. Utility of a Shortened Isometric Midthigh Pull Protocol for Assessing Rapid Force Production in Athletes. J. Strength Cond. Res. 2022, 36, 1819–1825. [Google Scholar] [CrossRef]
  49. Sahaly, R.; Vandewalle, H.; Driss, T.; Monod, H. Maximal voluntary force and rate of force development in humans—Importance of instruction. Eur. J. Appl. Physiol. 2001, 85, 345–350. [Google Scholar] [CrossRef]
  50. Rasp, D.M.; Paternoster, F.K.; Hanika, F.; Schwirtz, A. Comparison of two procedures of the 90:20 isometric posterior chain test regarding the detection of hamstring muscle fatigue in soccer. Sport Sci. Health 2025, 1, 1–11. [Google Scholar] [CrossRef]
  51. Franceschi, A.; Robinson, M.A.; Owens, D.J.; Brownlee, T.; Connolly, D.R.; Coutts, A.J.; Bravo, D.F.; Enright, K. Post-Match Recovery Responses in Italian SerieA Youth Soccer Players: Effects of Manipulating Training Load 48 h After Match Play. Eur. J. Sport Sci. 2025, 25, e12297. [Google Scholar] [CrossRef]
  52. Springham, M.; Singh, N.; Stewart, P.; Matthews, J.; Jones, I.; Norton-Sherwood, C.; May, D.; Sharma, S.T.; Salter, J.; Strudwick, A.J.; et al. Acute neuromuscular and perceptual responses to U-18 English Premier League academy football match play. Eur. J. Sport Sci. 2024, 24, 1405–1413. [Google Scholar] [CrossRef] [PubMed]
  53. Dos’Santos, T.; Jones, P.A.; Comfort, P.; Thomas, C. Effect of Different Onset Thresholds on Isometric Midthigh Pull Force-Time Variables. J. Strength Cond. Res. 2017, 31, 3463–3473. [Google Scholar] [CrossRef]
  54. Dos’Santos, T.; Jones, P.A.; Kelly, J.; McMahon, J.J.; Comfort, P.; Thomas, C. Effect of Sampling Frequency on Isometric Midthigh-Pull Kinetics. Int. J. Sports Physiol. Perform. 2019, 14, 525–530. [Google Scholar] [CrossRef]
  55. Ripley, N.; Fahey, J.T.; Comfort, P. The Effect of Different Onset Thresholds on Isometric Hamstring Force-Time Variables Using Force Plates. J. Appl. Sport Sci. 2025, 9, 24–39. [Google Scholar] [CrossRef]
  56. Guppy, S.N.; Brady, C.J.; Kotani, Y.; Connolly, S.; Comfort, P.; Lake, J.P.; Haff, G.G. A comparison of manual and automatic force-onset identification methodologies and their effect on force-time characteristics in the isometric midthigh pull. Sports Biomech. 2024, 23, 1663–1680. [Google Scholar] [CrossRef]
  57. Bettariga, F.; Bishop, C.; Martorelli, L.; Turner, A.; Lazzarini, S.G.; Algeri, C.; Maestroni, L. Authors’ Response: To “Letter to the Editor: ‘Acute Effects of a Fatiguing Protocol on Peak Force and Rate of Force Development of the Hamstring Muscles in Soccer Players’”. J. Sci. Sport Exerc. 2024, 6, 189–191. [Google Scholar] [CrossRef]
  58. Arampazis, A.; Karamanidis, K.; Stafilidis, S.; Morey-Klapsing, G.; DeMonte, G.; Bruggemann, G.-P. Effect of different ankle- and knee-joint positions on gastrocnemius medialis fascicle length and EMG activity during isometric plantar flexion. J. Biomech. 2006, 39, 1891–1902. [Google Scholar] [CrossRef]
  59. Rhodes, D.; Jeffery, J.; Brook-Sutton, D.; Alexander, J. Test-Retest Reliability of the Isometric Soleus Strength Test in Elite Male Academy Footballers. Int. J. Sports Phys. Ther. 2022, 17, 286–292. [Google Scholar] [CrossRef]
  60. O’Neill, S.; Weeks, A.; Nørgaard, J.E.; Jorgensen, M.G. Validity and intrarater reliability of a novel device for assessing Plantar flexor strength. PLoS ONE 2023, 18, 1–12. [Google Scholar] [CrossRef] [PubMed]
  61. Warneke, K.; Keiner, M.; Lohmann, L.H.; Hillebrecht, M.; Wirth, K.; Schiemann, S. The Influence of Maximum Strength Performance in Seated Calf Raises on Counter Movement Jump and Squat Jump in Elite Junior Basketball Players. SportMont 2022, 2, 3–8. [Google Scholar] [CrossRef]
  62. Warneke, K.; Wohlann, T.; Lohmann, L.H.; Wirth, K.; Schiemann, S. Acute effects of long-lasting stretching and strength training on maximal strength and flexibility in the calf muscle. Ger. J. Exerc. Sport Res. 2023, 53, 148–154. [Google Scholar] [CrossRef]
  63. Glaied, M.; Whiteley, R. Excellent Reliability for an Instrumented Test of Ankle Plantarflexion Force. Int. J. Sports Phys. Ther. 2025, 20, 263–274. [Google Scholar] [CrossRef]
  64. Leabeater, A.J.; Clarke, A.C.; James, L.; Huynh, M.; Driller, M.W. Under the Gun: Percussive Massage Therapy and Physical and Perceptual Recovery in Active Adults. J. Athl. Train. 2024, 59, 310–316. [Google Scholar] [CrossRef]
  65. Dorn, T.W.; Schanche, A.G.; Pandy, M.G. Muscular strategy shift in human running: Dependence of running speed on hip and ankle muscle performance. J. Exp. Biol. 2012, 215, 1944–1956. [Google Scholar] [CrossRef] [PubMed]
  66. O’Neill, S.; Barry, S.; Watson, P. Plantar exor strength and endurance de cits associated with mid-portion Achilles tendinopathy: The role of soleus. Phys. Ther. Sport 2019, 37, 69–76. [Google Scholar] [CrossRef]
  67. Winter, D.A.; Sidwall, H.G.; Hobson, D.A. Measurement and reduction of noise in kinematics of locomotion. J. Biomech. 1974, 7, 157–159. [Google Scholar] [CrossRef]
  68. Beckham, G.K.; Suchomel, T.; Mizuguchi, S. Force Plate Use in Performance Monitoring and Sport Science. New Stud. Athl. 2014, 29, 25–37. [Google Scholar]
  69. Smith, L.; Jones, P. The influence of common testing floor surfaces on force plate data: Implications for standardisation. bioRxiv 2025. [Google Scholar] [CrossRef]
  70. Hori, N.; Newton, R.U.; Kawamori, N.; McGuigan, M.; Kraemer, W.J.; Nosaka, K. Reliability of Performance Measurements Derived from Ground Reaction Force Data During Countermovement Jump and the Influence of Sampling Frequency. J. Strength Cond. Res. 2009, 23, 874–882. [Google Scholar] [CrossRef]
  71. Ives, J.C.; Wigglesworth, J.K. Sampling rate effects on surface EMG timing and amplitude measures. Clin. Biomech. 2003, 18, 543–552. [Google Scholar] [CrossRef]
  72. Nyquist, H. Certain topics in telegraph transmission theory. Trans. Am. Inst. Electr. Eng. 1928, 47, 617–644. [Google Scholar] [CrossRef]
  73. Street, G.; McMillan, S.; Board, W.; Rasmussen, M.; Heneghan, M.J. Sources of Error in Determining Countermovement Jump Height with the Impulse Method. J. Appl. Biomech. 2001, 17, 43–54. [Google Scholar] [CrossRef]
  74. Owen, N.; Watkins, J.; Kilduff, L.; Bevan, H.; Bennett, M. Development of a criterion method to determine peak mechanical power output in a countermovement jump. J. Strength Cond. Res. 2014, 28, 1552–1558. [Google Scholar] [CrossRef] [PubMed]
  75. Crenna, F.; Rossi, G.B.; Berardengo, M. Filtering Biomechanical Signals in Movement Analysis. Sensors 2021, 21, 4580. [Google Scholar] [CrossRef]
  76. Dos’Santos, T.; Lake, J.; Jones, P.A.; Comfort, P. Effect of Low-Pass Filtering on Isometric Midthigh Pull Kinetics. J. Strength Cond. Res. 2018, 32, 983–989. [Google Scholar] [CrossRef] [PubMed]
  77. Ladlow, P.; Suffield, C.; Greeves, J.P.; Comfort, P.; Hughes, J.; Cassidy, R.P.; Bennett, A.N.; Coppack, R.J. How ‘STRONG’ is the British Army? BMJ Mil. Health 2024, 170, 283–286. [Google Scholar] [CrossRef] [PubMed]
Standards 05 00030 g001
Figure 1. Key considerations for practitioners when using isometric hamstring assessments enabling the formation of standard department operating procedures. A. 90:20, B. 90:90, C. 30:30.
Figure 1. Key considerations for practitioners when using isometric hamstring assessments enabling the formation of standard department operating procedures. A. 90:20, B. 90:90, C. 30:30.
Standards 05 00030 g001
Standards 05 00030 g002
Figure 2. Key considerations for practitioners when using isometric plantar flexor assessments, enabling the formation of standard department operating procedures.
Figure 2. Key considerations for practitioners when using isometric plantar flexor assessments, enabling the formation of standard department operating procedures.
Standards 05 00030 g002
Table 3. Recommendations for future research on single joint isometric assessments using force plates.
Table 3. Recommendations for future research on single joint isometric assessments using force plates.
Construct validity of isometric hamstring and plantar flexor strength assessments with a comparison to gold standard assessments (i.e., isokinetic dynamometry).
Effect of specific cueing on maximal or rapid force and the orientation of force production in isometric hamstring and plantar flexor assessments.
Relationship between isometric hamstring and plantar strength assessments and performance (e.g., sprint, jump, and sport performance).
Sensitivity of measurements of isometric hamstrings and plantar flexor assessments in monitoring acute fatigue and tracking longitudinal changes in force-generating characteristics.
Return to play or performance assessment criteria for lower limb injuries (e.g., hamstring or ACL) using isometric hamstring and plantar flexor assessments (i.e., phase progression thresholds).
Normative data for isometric hamstring and plantar assessments across populations (e.g., sport, general population, and tactical populations).
Prospective and retrospective assessment of lower limb injuries with consideration of isometric hamstring and plantar flexor strength or asymmetry (e.g., whether low isometric hamstring strength is related to future or previous hamstring injuries).
ACL = anterior cruciate ligament; 90:90 = 90° degrees of hip and knee flexion; 40:NR = 40° degrees of hip and not reported knee flexion; 60:75 = 60° degrees of hip and 75° knee flexion; NR:20 = hip not reported and 20° knee flexion.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Ripley, N.; Fahey, J.; Williams, J.; Smith, L.; Ross, S.; Bramah, C.; Comfort, P. Standardization and Utilization of Lower Limb Single Joint Isometric Force Plate Assessments and Recommendations for Future Research. Standards 2025, 5, 30. https://doi.org/10.3390/standards5040030

AMA Style

Ripley N, Fahey J, Williams J, Smith L, Ross S, Bramah C, Comfort P. Standardization and Utilization of Lower Limb Single Joint Isometric Force Plate Assessments and Recommendations for Future Research. Standards. 2025; 5(4):30. https://doi.org/10.3390/standards5040030

Chicago/Turabian Style

Ripley, Nicholas, Jack Fahey, James Williams, Laura Smith, Steven Ross, Christopher Bramah, and Paul Comfort. 2025. "Standardization and Utilization of Lower Limb Single Joint Isometric Force Plate Assessments and Recommendations for Future Research" Standards 5, no. 4: 30. https://doi.org/10.3390/standards5040030

APA Style

Ripley, N., Fahey, J., Williams, J., Smith, L., Ross, S., Bramah, C., & Comfort, P. (2025). Standardization and Utilization of Lower Limb Single Joint Isometric Force Plate Assessments and Recommendations for Future Research. Standards, 5(4), 30. https://doi.org/10.3390/standards5040030

Article Metrics

Back to TopTop