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1.
Sci Rep ; 14(1): 10448, 2024 05 07.
Article En | MEDLINE | ID: mdl-38714802

Hip muscle weakness can be a precursor to or a result of lower limb injuries. Assessment of hip muscle strength and muscle motor fatigue in the clinic is important for diagnosing and treating hip-related impairments. Muscle motor fatigue can be assessed with surface electromyography (sEMG), however sEMG requires specialized equipment and training. Inertial measurement units (IMUs) are wearable devices used to measure human motion, yet it remains unclear if they can be used as a low-cost alternative method to measure hip muscle fatigue. The goals of this work were to (1) identify which of five pre-selected exercises most consistently and effectively elicited muscle fatigue in the gluteus maximus, gluteus medius, and rectus femoris muscles and (2) determine the relationship between muscle fatigue using sEMG sensors and knee wobble using an IMU device. This work suggests that a wall sit and single leg knee raise activity fatigue the gluteus medius, gluteus maximus, and rectus femoris muscles most reliably (p < 0.05) and that the gluteus medius and gluteus maximus muscles were fatigued to a greater extent than the rectus femoris (p = 0.031 and p = 0.0023, respectively). Additionally, while acceleration data from a single IMU placed on the knee suggested that more knee wobble may be an indicator of muscle fatigue, this single IMU is not capable of reliably assessing fatigue level. These results suggest the wall sit activity could be used as simple, static exercise to elicit hip muscle fatigue in the clinic, and that assessment of knee wobble in addition to other IMU measures could potentially be used to infer muscle fatigue under controlled conditions. Future work examining the relationship between IMU data, muscle fatigue, and multi-limb dynamics should be explored to develop an accessible, low-cost, fast and standardized method to measure fatiguability of the hip muscles in the clinic.


Electromyography , Exercise , Hip , Muscle Fatigue , Humans , Electromyography/methods , Muscle Fatigue/physiology , Male , Exercise/physiology , Adult , Hip/physiology , Female , Muscle, Skeletal/physiology , Young Adult , Knee/physiology
2.
J Sports Sci ; 42(7): 599-610, 2024 Apr.
Article En | MEDLINE | ID: mdl-38734986

Unanticipated trunk perturbation is commonly observed when anterior cruciate ligament (ACL) injuries occur during direction-changing manoeuvres. This study aimed to quantify the effect of mid-flight medial-lateral external trunk perturbation directions/locations on ACL loading variables during sidestep cuttings. Thirty-two recreational athletes performed sidestep cuttings under combinations of three perturbation directions (no-perturbation, ipsilateral-perturbation, and contralateral-perturbation relative to the cutting leg) and two perturbation locations (upper-trunk versus lower-trunk). The pushing perturbation was created by customised devices releasing a slam ball to contact participants near maximum jump height prior to cutting. Perturbation generally resulted in greater peak vertical ground reaction force and slower cutting velocity. Upper-trunk contralateral perturbation showed the greatest lateral trunk bending away from the travel direction, greatest peak knee flexion and abduction angles, and greatest peak internal knee adduction moments compared to other conditions. Such increased ACL loading variables were likely due to the increased lateral trunk bending and whole-body horizontal velocity away from the cutting direction caused by the contralateral perturbation act at the upper trunk. The findings may help understand the mechanisms of indirect contact ACL injuries and develop effective cutting techniques for ACL injury prevention.


Anterior Cruciate Ligament Injuries , Torso , Humans , Torso/physiology , Biomechanical Phenomena , Anterior Cruciate Ligament Injuries/physiopathology , Anterior Cruciate Ligament Injuries/prevention & control , Male , Young Adult , Female , Anterior Cruciate Ligament/physiology , Movement/physiology , Knee/physiology , Adult
3.
PLoS One ; 19(5): e0301872, 2024.
Article En | MEDLINE | ID: mdl-38776288

BACKGROUND: The current clinical gold standard for assessing isometric quadriceps muscle strength is an isokinetic dynamometer (IKD). However, in clinics without an IKD, clinicians default to using handheld dynamometers (HHD), which are less reliable and accurate than the IKD, particularly for large muscle groups. A novel device (ND) was developed that locks the weight stack of weight machines, and measures forces applied to the machine, turning this equipment into an isometric dynamometer. The objectives of this study were to characterize the test-retest reliability of the ND, determine the within-day and between-days inter-rater reliability and concurrent validity compared with that of the HHD, in healthy volunteers (HV) and individuals with knee osteoarthritis (OA) for measuring knee extensors isometric muscle force. MATERIALS AND METHODS: 29 healthy (age = 28.4 ± 7.4 years) and 15 knee OA (age = 37.6 ± 13.4 years) participants completed three maximum force isometric strength testing trials on dominant side knee extensor muscles on three devices (ND, HHD, and IKD) in two separate sessions by two raters. The maximum force (Fmax) produced, and the force-time series were recorded. Reliability and validity were assessed using Intraclass Correlation Coefficient (ICC), Bland-Altman Plots, Pearson's r, and cross-correlations. RESULTS: The ND demonstrated excellent test-retest reliability (ICC2,3 = 0.97). The within-day (ICC2,3 = 0.88) and between-day inter-rater reliability (ICC2,3 = 0.87) was good for HHD. The ND showed excellent within-day (ICC2,3 = 0.93) and good between-day (ICC2,3 = 0.89) inter-rater reliability. The Bland-Altman analysis revealed HHD systematic bias and underestimation of force particularly with quadriceps force values exceeding 450 N. Mean differences were found in maximum force between HHD vs. IKD (MDabs = 58 N, p < .001) but not the HHD vs. ND (MDabs = 24 N, p = .267) or ND vs. IKD (MDabs = 34 N, p = .051). The concurrent validity of Fmax (r = 0.81) and force-time curve correlation (0.96 ± 0.05) were the highest between the ND and IKD. CONCLUSIONS: The ND's test-retest reliability and concurrent validity make it a potential strength assessment tool with utility in physical therapy and fitness settings for large muscle groups such as the knee extensors.


Isometric Contraction , Muscle Strength Dynamometer , Muscle Strength , Humans , Adult , Male , Female , Reproducibility of Results , Muscle Strength/physiology , Middle Aged , Isometric Contraction/physiology , Osteoarthritis, Knee/physiopathology , Quadriceps Muscle/physiology , Young Adult , Knee Joint/physiology , Knee Joint/physiopathology , Knee/physiology , Knee/physiopathology
4.
J Bodyw Mov Ther ; 38: 554-561, 2024 Apr.
Article En | MEDLINE | ID: mdl-38763608

INTRODUCTION: The effects of stretching exercises on muscle strength have been widely researched in the literature, however, there are no studies investigating the effects of Pilates stretching. OBJECTIVE: To compare the effects of static stretching and Pilates stretching on the concentric muscle strength of the knee extensors and flexors. METHOD: 102 trained young adults were randomized into three groups: static stretching (n = 33); Pilates stretching (n = 34); control (n = 35). Isokinetic evaluation of the knee extensor and flexor muscles was performed at 60°/s and 180°/s, pre and post acute intervention with stretching. Interventions in the static stretching and Pilates stretching groups occurred in 3 sets x 30 s for each body region considered (a-knee extensor muscles; b-knee flexor muscles). The control group did not perform any intervention. RESULTS: No difference (p > 0.05) was observed between the groups after the intervention. There was only a significant intragroup improvement for the control group on the isokinetic muscle strength of the knee flexors at 180°/s, with a moderate effect size, considering the entire sample (p = 0.040; d = 0.42) and when considering only male gender (p = 0.010; d = 0.60). CONCLUSION: Static stretching or Pilates stretching performed as a warm-up did not impair or enhance the concentric muscle strength performance of the knee extensors and flexors. In this way, both forms of stretching can be considered as preparatory exercises before muscle strength training.


Exercise Movement Techniques , Muscle Strength , Muscle Stretching Exercises , Muscle, Skeletal , Humans , Muscle Stretching Exercises/physiology , Male , Female , Muscle Strength/physiology , Young Adult , Exercise Movement Techniques/methods , Muscle, Skeletal/physiology , Adult , Knee/physiology , Knee Joint/physiology , Range of Motion, Articular/physiology
5.
Scand J Med Sci Sports ; 34(4): e14615, 2024 Apr.
Article En | MEDLINE | ID: mdl-38556845

We investigated the effects of far-infrared radiation (FIR) lamp therapy on changes in muscle damage and performance parameters following six sets of 15-min Loughborough intermittent shuttle test (LIST), a simulated soccer match. Twenty-four elite female soccer players (20-24 y) were assigned into FIR or sham treatment group (n = 12/group). The participants received a 60-min FIR or sham treatment (30 min per muscle) over knee extensors (KE) and flexors (KF) at 2, 25, 49, 73, and 97 h post-LIST. Maximal voluntary isometric contraction (MVC) torque and muscle soreness of the KE and KF, plasma creatine kinase (CK) activity as muscle damage markers, and several performance parameters including countermovement jump (CMJ) and Yo-Yo intermittent recovery test level 1 (YYIR1) were measured before and 1, 24, 48, 72, 96, and 120 h post-LIST. Changes in the measures were compared between groups by a mixed-design two-way ANOVA. The running distance covered during LIST and changes in the measures at 1-h post-LIST (before the treatment) were similar (p = 0.118-0.371) between groups. Changes in muscle damage markers at 24-120 h post-LIST were smaller (p < 0.05, η2 = 0.208-0.467) for the FIR (e.g., MVC-KE torque decrease at 48-h post-LIST: -1 ± 2%, peak KE soreness: 16 ± 10 mm, peak CK: 172 ± 42 IU/L) than sham group (-11 ± 9%, 33 ± 7 mm, 466 ± 220 IU/L, respectively). Performance parameters recovered faster (p < 0.05, η2 = 0.142-0.308) to baseline for the FIR (e.g., decreases at 48-h post-LIST; CMJ: 0 ± 1%, YYIR1: 0 ± 1%) than sham group (-6 ± 2%, -9 ± 6%, respectively). These results suggest that the FIR lamp therapy was effective for enhancing recovery from a soccer match.


Athletic Performance , Soccer , Humans , Female , Soccer/physiology , Myalgia/radiotherapy , Knee/physiology , Knee Joint , Athletic Performance/physiology
6.
Scand J Med Sci Sports ; 34(4): e14621, 2024 Apr.
Article En | MEDLINE | ID: mdl-38597348

Tendon properties impact human locomotion, influencing sports performance, and injury prevention. Hamstrings play a crucial role in sprinting, particularly the biceps femoris long head (BFlh), which is prone to frequent injuries. It remains uncertain if BFlh exhibits distinct mechanical properties compared to other hamstring muscles. This study utilized free-hand three-dimensional ultrasound to assess morphological and mechanical properties of distal hamstrings tendons in 15 men. Scans were taken in prone position, with hip and knee extended, at rest and during 20%, 40%, 60%, and 80% of maximal voluntary isometric contraction of the knee flexors. Tendon length, volume, cross-sectional area (CSA), and anteroposterior (AP) and mediolateral (ML) widths were quantified at three locations. Longitudinal and transverse deformations, stiffness, strain, and stress were estimated. The ST had the greatest tendon strain and the lowest stiffness as well as the highest CSA and AP and ML width strain compared to other tendons. Biceps femoris short head (BFsh) exhibited the least strain, AP and ML deformation. Further, BFlh displayed the highest stiffness and stress, and BFsh had the lowest stress. Additionally, deformation varied by region, with the proximal site showing generally the lowest CSA strain. Distal tendon mechanical properties differed among the hamstring muscles during isometric knee flexions. In contrast to other bi-articular hamstrings, the BFlh high stiffness and stress may result in greater energy absorption by its muscle fascicles, rather than the distal tendon, during late swing in sprinting. This could partly account for the increased incidence of hamstring injuries in this muscle.


Hamstring Muscles , Muscle, Skeletal , Male , Humans , Muscle, Skeletal/physiology , Tendons/diagnostic imaging , Tendons/physiology , Hamstring Muscles/physiology , Knee/diagnostic imaging , Knee/physiology , Isometric Contraction/physiology , Ultrasonography
7.
Sensors (Basel) ; 24(8)2024 Apr 11.
Article En | MEDLINE | ID: mdl-38676056

This paper introduces a method for measuring 3D tibiofemoral kinematics using a multi-channel A-mode ultrasound system under dynamic conditions. The proposed system consists of a multi-channel A-mode ultrasound system integrated with a conventional motion capture system (i.e., optical tracking system). This approach allows for the non-invasive and non-radiative quantification of the tibiofemoral joint's six degrees of freedom (DOF). We demonstrated the feasibility and accuracy of this method in the cadaveric experiment. The knee joint's motions were mimicked by manually manipulating the leg through multiple motion cycles from flexion to extension. To measure it, six custom ultrasound holders, equipped with a total of 30 A-mode ultrasound transducers and 18 optical markers, were mounted on various anatomical regions of the lower extremity of the specimen. During experiments, 3D-tracked intra-cortical bone pins were inserted into the femur and tibia to measure the ground truth of tibiofemoral kinematics. The results were compared with the tibiofemoral kinematics derived from the proposed ultrasound system. The results showed an average rotational error of 1.51 ± 1.13° and a translational error of 3.14 ± 1.72 mm for the ultrasound-derived kinematics, compared to the ground truth. In conclusion, this multi-channel A-mode ultrasound system demonstrated a great potential of effectively measuring tibiofemoral kinematics during dynamic motions. Its improved accuracy, nature of non-invasiveness, and lack of radiation exposure make this method a promising alternative to incorporate into gait analysis and prosthetic kinematic measurements later.


Imaging, Three-Dimensional , Knee Joint , Ultrasonography , Humans , Biomechanical Phenomena , Knee Joint/physiology , Knee Joint/diagnostic imaging , Ultrasonography/methods , Imaging, Three-Dimensional/methods , Tibia/diagnostic imaging , Tibia/physiology , Range of Motion, Articular/physiology , Femur/physiology , Femur/diagnostic imaging , Knee/physiology , Knee/diagnostic imaging
8.
Sensors (Basel) ; 24(8)2024 Apr 21.
Article En | MEDLINE | ID: mdl-38676262

Knee rehabilitation therapy after trauma or neuromotor diseases is fundamental to restore the joint functions as best as possible, exoskeleton robots being an important resource in this context, since they optimize therapy by applying tailored forces to assist or resist movements, contributing to improved patient outcomes and treatment efficiency. One of the points that must be taken into account when using robots in rehabilitation is their interaction with the patient, which must be safe for both and guarantee the effectiveness of the treatment. Therefore, the objective of this study was to assess the interaction between humans and an exoskeleton during the execution of knee flexion-extension movements under various configurations of robot assistance and resistance. The evaluation encompassed considerations of myoelectric activity, muscle recruitment, robot torque, and performed movement. To achieve this, an experimental protocol was implemented, involving an individual wearing the exoskeleton and executing knee flexion-extension motions while seated, with the robot configured in five distinct modes: passive (P), assistance on flexion (FA), assistance on extension (EA), assistance on flexion and extension (CA), and resistance on flexion and extension (CR). Results revealed distinctive patterns of movement and muscle recruitment for each mode, highlighting the complex interplay between human and robot; for example, the largest RMS tracking errors were for the EA mode (13.72 degrees) while the smallest for the CR mode (4.47 degrees), a non-obvious result; in addition, myoelectric activity was demonstrated to be greater for the completely assisted mode than without the robot (the maximum activation levels for the vastus medialis and vastus lateralis muscles were more than double those when the user had assistance from the robot). Tracking errors, muscle activations, and torque values varied across modes, emphasizing the need for careful consideration in configuring exoskeleton assistance and resistance to ensure effective and safe rehabilitation. Understanding these human-robot interactions is essential for developing precise rehabilitation programs, optimizing treatment effectiveness, and enhancing patient safety.


Exoskeleton Device , Knee Joint , Robotics , Humans , Robotics/methods , Knee Joint/physiology , Male , Range of Motion, Articular/physiology , Biomechanical Phenomena , Electromyography/methods , Adult , Torque , Muscle, Skeletal/physiology , Knee/physiology , Movement/physiology
9.
Percept Mot Skills ; 131(3): 805-817, 2024 Jun.
Article En | MEDLINE | ID: mdl-38613514

Single-leg knee crutches are a relatively new, hands-free mobility assistive device with benefits over standard axillary crutches. Our main goal in this study was to evaluate balance ability in a healthy population upon first exposure to the knee crutch device. We had 20 healthy individuals (M age = 21.1; SD = 1.5 years) complete baseline static and dynamic balance tests on a force plate, followed by knee crutch fitting, a self-selected duration of ambulation practice, and another round of balance testing while wearing the knee crutch. We used the BTrackS Balance Test (BBT) to measure static balance, and the BTrackS Limits of Stability (BLOS) test to measure dynamic balance, and we created a custom lateral bias score from the BLOS results. On average, participants self-selected 3.1 minutes of ambulation practice. Wearing the knee crutch caused a near doubling of static balance path length and a large reduction in percentile ranking on the BBT. Dynamic balance area was more than halved (p < .001), with lateral bias scores during the BLOS, indicating that participants heavily favored their non-crutched leg (p < .001). Our results indicate that static and dynamic balance were significantly altered when wearing the knee crutch, and participants seemed to switch to a single leg stance strategy. Despite these balance changes, participants were quickly ready and willing to complete independent ambulation and balance testing procedures using the single-leg knee crutch.


Crutches , Postural Balance , Humans , Postural Balance/physiology , Male , Female , Young Adult , Adult , Knee/physiology
10.
Exp Physiol ; 109(6): 915-925, 2024 Jun.
Article En | MEDLINE | ID: mdl-38595307

Post-activation potentiation (PAP) is defined as an enhanced contractile response of a muscle following its own contractile activity and is influenced by the intensity and duration of the conditioning contraction. The aim of this study was to determine if the combination of intensity and duration, that is, torque-time integral (TTI) is a determinant of PAP amplitude. We compared PAP amplitude following low-to-maximal voluntary conditioning contraction intensities with and without similar TTI in the knee extensors. Twelve healthy males completed two experimental sessions. Femoral nerve stimulation was applied to evoke single twitches on the relaxed quadriceps before and after isometric conditioning contractions of knee extensors. In one session, participants performed conditioning contractions without similar TTI (6 s at 100, 80, 60, 40 and 20% maximal voluntary contraction (MVC)), while they performed conditioning contractions with similar TTI in the other session (6 s at 100%, 7.5 s at 80%, 10 s at 60%, 15 s at 40%, and 30 s at 20% MVC). In both sessions, PAP amplitude was related to conditioning contraction intensity. The higher the conditioning contraction intensity with or without similar TTI, the higher PAP. Significant correlations were found (i) between PAP and conditioning contraction intensity with (r2 = 0.70; P < 0.001) or without similar TTI (r2 = 0.64; P < 0.001), and (ii) between PAP with and without similar TTI (r2 = 0.82; P < 0.001). The results provide evidence that TTI has a minor influence on PAP in the knee extensors. This suggests that to optimize the effect of PAP, it is more relevant to control the intensity of the contraction rather than the TTI.


Isometric Contraction , Torque , Humans , Male , Isometric Contraction/physiology , Adult , Young Adult , Quadriceps Muscle/physiology , Electric Stimulation/methods , Knee/physiology , Muscle, Skeletal/physiology , Electromyography/methods , Muscle Contraction/physiology , Femoral Nerve/physiology
11.
J Sports Sci ; 42(5): 404-414, 2024 Mar.
Article En | MEDLINE | ID: mdl-38602304

The purpose was to compare two non-laboratory based running retraining programs on lower limb and trunk kinematics in recreational runners. Seventy recreational runners (30 ± 7.3 years old, 40% female) were randomised to a barefoot running group (BAR), a group wearing a digital metronome with their basal cadence increased by 10% (CAD), and a control group (CON). BAR and CAD groups included intervals from 15 to 40 min over 10 weeks and 3 days/week. 3D sagittal kinematics of the ankle, knee, hip, pelvis, and trunk were measured before and after the retraining program, at comfortable and high speeds. A 3 × 2 mixed ANOVA revealed that BAR and CAD groups increased knee and hip flexion at footstrike, increased peak hip flexion during stance and flight phase, decreased peak hip extension during flight phase, and increased anterior pelvic tilt at both speeds after retraining. In addition, BAR increased ankle plantar flexion at footstrike and increased anterior trunk tilt. Both retraining programs demonstrated significant moderate to large effect size changes in parameters that could reduce the mechanical risks of injury associated with excessive knee stress, which is of interest to coaches, runners and those prescribing rehabilitation and injury prevention programs.


Lower Extremity , Pelvis , Running , Torso , Humans , Running/physiology , Biomechanical Phenomena , Female , Male , Torso/physiology , Adult , Lower Extremity/physiology , Pelvis/physiology , Foot/physiology , Young Adult , Knee/physiology , Ankle/physiology , Hip/physiology , Gait/physiology
12.
Ann Biomed Eng ; 52(6): 1591-1603, 2024 Jun.
Article En | MEDLINE | ID: mdl-38558356

Kinematic tracking of native anatomy from stereo-radiography provides a quantitative basis for evaluating human movement. Conventional tracking procedures require significant manual effort and call for acquisition and annotation of subject-specific volumetric medical images. The current work introduces a framework for fully automatic tracking of native knee anatomy from dynamic stereo-radiography which forgoes reliance on volumetric scans. The method consists of three computational steps. First, captured radiographs are annotated with segmentation maps and anatomic landmarks using a convolutional neural network. Next, a non-convex polynomial optimization problem formulated from annotated landmarks is solved to acquire preliminary anatomy and pose estimates. Finally, a global optimization routine is performed for concurrent refinement of anatomy and pose. An objective function is maximized which quantifies similarities between masked radiographs and digitally reconstructed radiographs produced from statistical shape and intensity models. The proposed framework was evaluated against manually tracked trials comprising dynamic activities, and additional frames capturing a static knee phantom. Experiments revealed anatomic surface errors routinely below 1.0 mm in both evaluation cohorts. Median absolute errors of individual bone pose estimates were below 1.0 ∘ or mm for 15 out of 18 degrees of freedom in both evaluation cohorts. Results indicate that accurate pose estimation of native anatomy from stereo-radiography may be performed with significantly reduced manual effort, and without reliance on volumetric scans.


Knee , Humans , Knee/diagnostic imaging , Knee/anatomy & histology , Knee/physiology , Knee Joint/diagnostic imaging , Knee Joint/anatomy & histology , Knee Joint/physiology , Phantoms, Imaging , Radiography , Models, Statistical
13.
Exp Gerontol ; 190: 112430, 2024 Jun 01.
Article En | MEDLINE | ID: mdl-38608793

PURPOSE: We investigated the effect of an unsupervised, body mass- home-based resistance training program in older adults performed at either a fast or slow contractile speed on changes to muscle-power, -volume, -architecture, and fatigue resistance of the knee extensors. METHODS: Thirty-two male older adults (age 65-88 years) were separated into 1) fast-speed exercise (Fast-group), 2) slow-speed exercise (Slow-group), and 3) no exercise (Control-group) groups. Participants in the exercise groups performed 30-45 repetitions of knee-extension and sit-to-stand exercises 3 times a week for 8 weeks with different exercise speed between the groups. Before and after the intervention period, the following variables were measured: Isotonic power, isometric strength, twitch contractile properties, muscle-activity, -architecture, and -quality, neuromuscular fatigue resistance of the knee extensors, and thigh muscle volume. RESULTS: Peak power was increased in both the Fast-group (+24 %, P < 0.01, d = 0.65) and Slow-group (+12 %, P < 0.05, d = 0.33) but not in the Control-group. Training increased pennation angle of the vastus lateralis in both the Fast-group (+8 %, P < 0.01, d = 0.42) and Slow-group (+8 %, P < 0.01, d = 0.42), while only the Fast-group showed increase in pennation angle of the rectus femoris (+12 %, P < 0.01, d = 0.64) and thigh muscle volume (+16 %, P < 0.01, d = 0.52). There was no time × group interaction effect for the other neuromuscular measures. CONCLUSIONS: Unsupervised, body mass- and home-based resistance training performed at either fast or slow speeds can improve muscle power in older adults, while fast-speed exercise may be preferable over slow-speed owing to the relatively greater improvement of muscle-power, -volume, -architecture, and better time efficiency.


Muscle Strength , Resistance Training , Humans , Resistance Training/methods , Aged , Male , Muscle Strength/physiology , Aged, 80 and over , Muscle Fatigue/physiology , Muscle, Skeletal/physiology , Isometric Contraction/physiology , Knee/physiology , Muscle Contraction/physiology
14.
J Sports Sci ; 42(3): 263-269, 2024 Feb.
Article En | MEDLINE | ID: mdl-38484285

Horizontal deceleration technique is an underpinning factor to musculoskeletal injury risk and performance in multidirectional sport. This study primarily assessed within- and between-session reliability of biomechanical and performance-based aspects of a horizontal deceleration technique and secondarily investigated the effects of limb dominance on reliability. Fifteen participants completed four horizontal decelerations on each leg during test and retest sessions. A three-dimensional motion analysis system was used to collect kinetic and kinematic data. Completion time, ground contact time, rate of horizontal deceleration, minimum centre of mass height, peak eccentric force, impulse ratio, touchdown distance, sagittal plane foot and knee angles at initial contact, maximum sagittal plane thorax angle, and maximum knee flexion moment were assessed. Coefficients of variation (COV) and intraclass correlation coefficients (ICC) were used to assess within- and between-session reliability, respectively. Seven variables showed "great" within-session reliability bilaterally (COV ≤9.13%). ICC scores were 'excellent' (≥0.91; n = 4), or 'good' (0.76-0.89; n = 7), bilaterally. Limb dominance affected five variables; three were more reliable for the dominant leg. This horizontal deceleration task was reliable for most variables, with little effect of limb dominance on reliability. This deceleration task may be reliably used to assess and track changes in deceleration technique in healthy adults.


Deceleration , Humans , Biomechanical Phenomena , Male , Reproducibility of Results , Female , Young Adult , Adult , Time and Motion Studies , Leg/physiology , Knee/physiology , Foot/physiology , Task Performance and Analysis
15.
Medicina (Kaunas) ; 60(3)2024 Feb 22.
Article En | MEDLINE | ID: mdl-38541093

Background and Objectives: Hypermobility has been linked to decreased knee performance, including isokinetic and isometric knee strength. This study aimed to determine whether athletes with and without knee hyperextension have different hamstring-to-quadriceps strength (H/Q) ratios and to investigate the associations between knee hyperextension indices and H/Q ratios and anthropometric characteristics. Materials and Methods: The sample consisted of 47 healthy male athletes without knee injuries aged 23.48 ± 3.54 years. The variables included the degree of knee hypermobility, isokinetic parameters of the leg musculature, and anthropometric indices. Differences between athletes with and without hyperextension were calculated using an independent sample t-test, effect sizes, and discriminant analysis, while associations between the variables were checked by Pearson's correlation coefficient and multiple regression analysis. Results: Athletes with hyperextended knees had shorter legs (t value = -2.23, p = 0.03, moderate ES) and shins (t = -2.64, p = 0.01, moderate ES) and a lower H/Q ratio at an angular velocity of 60°/s (t = -2.11, p = 0.04, moderate ES) than those in the nonhyperextended group did; these differences were supported by discriminant analysis (Wilks' L = 0.60, p = 0.01). An increase in the H/Q ratio at an angular velocity of 60°/s was associated with the degree of knee hypermobility (R = -0.29, p = 0.04). Conclusions: This research showed that athletes with knee hypermobility have weaker hamstring strength and thus a lower H/Q strength ratio at lower angular velocities. These findings suggest that targeted strength training programs for leg (i.e., hamstrings) muscles should help individuals with knee hypermobility.


Knee Joint , Knee , Male , Humans , Knee Joint/physiology , Knee/physiology , Muscle Strength/physiology , Leg/physiology , Athletes , Muscle, Skeletal/physiology
16.
J Sports Sci ; 42(4): 365-372, 2024 Feb.
Article En | MEDLINE | ID: mdl-38507567

Patellofemoral pain syndrome (PFPS) is a common injury among runners, and it is thought that abnormal lower extremity biomechanics contribute to its development. However, the relationship between biomechanical changes after a marathon and PFPS injury remains limited. This study aims to investigate whether differences in knee and hip kinematics and lower extremity muscle activities exist in recreational runners before and after a marathon. Additionally, it aims to explore the relationship between these biomechanical changes and the development of PFPS injury. 12 recreational runners participated in the study. Kinematics and muscle activities of the lower extremity were recorded during walking (5 km/h) and running (10 km/h) tasks within 24 hours before and within 5 hours after a marathon. After the marathon, there was a significant decrease in peak knee flexion (walking: p = 0.006; running: p = 0.006) and an increase in peak hip internal rotation (walking: p = 0.026; running: p = 0.015) during the stance phase of both walking and running compared to before the marathon. The study demonstrates a decrease in knee flexion and an increase in hip internal rotation during the stance phase of gait tasks after completing a marathon, which may increase the risk of developing PFPS injury.


Lower Extremity , Marathon Running , Muscle, Skeletal , Patellofemoral Pain Syndrome , Walking , Humans , Biomechanical Phenomena , Walking/physiology , Male , Adult , Muscle, Skeletal/physiology , Lower Extremity/physiology , Female , Marathon Running/physiology , Patellofemoral Pain Syndrome/physiopathology , Running/physiology , Gait/physiology , Hip Joint/physiology , Hip/physiology , Electromyography , Knee/physiology , Young Adult , Knee Joint/physiology , Rotation , Time and Motion Studies
17.
J Sports Sci Med ; 23(1): 34-45, 2024 Mar.
Article En | MEDLINE | ID: mdl-38455437

This study aimed to narrow down the possible mechanisms of Post-Activation Performance Enhancement (PAPE), especially if they are exclusively found in the muscle. It was therefore investigated whether (1) the PAPE effect is influenced by neural factors and (2) if Post-Activation-Potentiation (PAP) influences PAPE. Thirteen strength-trained participants (26.5 ± 3.2 years) took part in at least one of three interventions (PAP, PAPE-Electrical (PAPEE), and PAPE-Voluntary (PAPEV)). Conditioning contractions (CC) and testing involved isometric knee extensions performed on an isokinetic device at an 80° knee flexion angle. The CC was either performed voluntarily (PAP, PAPEV) or was evoked through electrical stimulation (PAPEE). Testing was performed at baseline and after two seconds, four minutes, eight minutes, and twelve minutes of the CC. Maximum voluntary isometric contractions (MVIC) for the PAPE trials and supramaximal twitches for the PAP trial were used for testing. Parameters of interest were peak torque and rate of torque development (RTD), and electromyography (EMG) amplitude of the quadriceps (only PAPE). Repeated measures ANOVA and simple contrast comparisons were used for statistical analysis. Peak torque (p < 0.001, η2p = 0.715) and RTD (p = 0. 005, η2p = 0.570) increased significantly during the PAP protocol immediately two seconds after the CC and decreased to near baseline values for the following time points (p > 0.05). Peak torque, RTD, and peak EMG showed no significant differences during PAPEE and PAPEV trials (p > 0.05). Due to the lack of a visible PAPE effect, the question of whether neural mechanisms influence PAPE cannot be answered. Due to the time course of the PAP analysis, it is questionable if these mechanisms play a role in PAPE. The assumption that the PAP mechanism influences PAPE cannot be confirmed for the same reason.


Knee Joint , Muscle, Skeletal , Adult , Humans , Young Adult , Electromyography , Isometric Contraction/physiology , Knee/physiology , Knee Joint/physiology , Muscle, Skeletal/physiology
18.
Biomech Model Mechanobiol ; 23(3): 1077-1090, 2024 Jun.
Article En | MEDLINE | ID: mdl-38459157

Cerebral palsy (CP) includes a group of neurological conditions caused by damage to the developing brain, resulting in maladaptive alterations of muscle coordination and movement. Estimates of joint moments and contact forces during locomotion are important to establish the trajectory of disease progression and plan appropriate surgical interventions in children with CP. Joint moments and contact forces can be estimated using electromyogram (EMG)-informed neuromusculoskeletal models, but a reduced number of EMG sensors would facilitate translation of these computational methods to clinics. This study developed and evaluated a muscle synergy-informed neuromusculoskeletal modelling approach using EMG recordings from three to four muscles to estimate joint moments and knee contact forces of children with CP and typically developing (TD) children during walking. Using only three to four experimental EMG sensors attached to a single leg and leveraging an EMG database of walking data of TD children, the synergy-informed approach estimated total knee contact forces comparable to those estimated by EMG-assisted approaches that used 13 EMG sensors (children with CP, n = 3, R2 = 0.95 ± 0.01, RMSE = 0.40 ± 0.14 BW; TD controls, n = 3, R2 = 0.93 ± 0.07, RMSE = 0.19 ± 0.05 BW). The proposed synergy-informed neuromusculoskeletal modelling approach could enable rapid evaluation of joint biomechanics in children with unimpaired and impaired motor control within a clinical environment.


Cerebral Palsy , Electromyography , Knee Joint , Knee , Humans , Cerebral Palsy/physiopathology , Child , Knee/physiopathology , Knee/physiology , Biomechanical Phenomena , Male , Knee Joint/physiopathology , Muscle, Skeletal/physiopathology , Muscle, Skeletal/physiology , Female , Models, Biological , Walking/physiology
19.
Am J Sports Med ; 52(5): 1328-1335, 2024 Apr.
Article En | MEDLINE | ID: mdl-38459686

BACKGROUND: It has been shown that chronic ankle instability (CAI) leads to abnormalities in neuromuscular control of more proximal joints than the ankle. Although strength of the hip and the ankle muscles has been largely investigated providing concordant results, limited evidence with contrasting results has been reported regarding knee extensor and flexor muscles. PURPOSE: To investigate maximal and submaximal isometric muscle strength in individuals with CAI. STUDY DESIGN: Controlled laboratory study. METHODS: Fifteen participants with unilateral CAI and 15 healthy matched controls were recruited. To quantify maximal strength, peak forces were recorded during a maximal isometric voluntary contraction of knee extensor and flexor muscles at 30° and 90° of knee flexion and normalized by the body weight of each participant. At both angles, submaximal isometric contractions at 20%, 50%, and 80% of the maximal voluntary isometric contraction were performed to analyze strength steadiness, in terms of coefficient of variation, and strength accuracy, in terms of absolute error. During all the assessments, knee extensor and flexor muscle activation was recorded by means of surface electromyography. RESULTS: Knee flexor maximal isometric strength was significantly lower in the injured limb of individuals with CAI in comparison with healthy controls at both 30° (0.15 ± 0.05 vs 0.20 ± 0.05; P < .05) and 90° (0.14 ± 0.04 vs 0.18 ± 0.05; P < .05). Knee extensor and flexor steadiness was significantly lower (higher coefficient of variation) in both the injured and the noninjured limbs of individuals with CAI in comparison with healthy individuals at 90° and at 30° for knee flexor steadiness of the injured limb. Knee extensor and flexor accuracy was lower (higher absolute error) in both the injured and noninjured limbs of individuals with CAI in comparison with healthy individuals, mainly at 30°, while at 90° it was lower only in the injured limb. No differences between the 2 groups were found for maximal isometric strength of knee extensor muscles, as well as for muscle activations. CONCLUSION: Individuals with CAI show abnormalities in maximal and submaximal isometric strength of knee flexor muscles, and submaximal strength of the knee extensor muscles. Further studies should deeply investigate mechanisms leading to these abnormalities. CLINICAL RELEVANCE: Rehabilitation interventions should consider abnormalities of neuromuscular control affecting joints more proximal than the ankle in individuals with CAI. REGISTRATION: NCT05273177 (ClinicalTrials.gov identifier).


Ankle , Joint Instability , Humans , Electromyography , Isometric Contraction/physiology , Knee/physiology , Knee Joint/physiology , Lower Extremity , Muscle Strength/physiology , Muscle, Skeletal/physiology
20.
J Biomech ; 165: 112026, 2024 Mar.
Article En | MEDLINE | ID: mdl-38417193

Induced acceleration analyses have expanded our understanding on the contributions of muscle forces to center of mass and segmental kinematics during a myriad of tasks. While these techniques have identified a subset of major muscle that contribute to locomotion, most analyses have included models with only one frontal plane degree of freedom (dof) actuated by the hip joint. The purpose of this study was to define the impact of including knee and subtalar joint frontal plane dof on model superposition accuracy and muscle specific contributions to mediolateral accelerations. Induced acceleration analyses were performed using OpenSim with the Lai model on a freely available dataset of one subject running at 4 m/s. Analyses were performed on four models (standard, with subtalar joint, with frontal plane knee, and combined frontal plane knee with subtalar) with the kinematic constraint and perturbation analyses. Root mean square error and correlations were computed against experimental kinematics. Adding frontal plane dofs improved mediolateral acceleration correlations on average by > 0.25 while only minimally impacting errors. The constraints method performed better than the perturbation method for mediolateral accelerations. Including frontal plane knee dof resulted in muscle and method specific responses. All muscles presented with a complete flip of polarity for constraint method, imparted by allowing the medial/lateral muscles to contribute according to their anatomical function. Only the gluteus medius flipped for the perturbation method. This study provides significant support for the inclusion of frontal plane knee and subtalar dof and the need for reevaluation of muscle contributions via induced acceleration.


Knee Joint , Knee , Humans , Knee Joint/physiology , Knee/physiology , Movement/physiology , Lower Extremity , Thigh , Muscle, Skeletal/physiology , Biomechanical Phenomena
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