Knee proprioception: a review of mechanisms, measurements, and implications of muscular fatigue

Autologous Matrix-Induced Chondrogenesis (AMIC) for Focal Chondral Lesions of the Knee: A 2-Year Follow-Up of Clinical, Proprioceptive, and Isokinetic Evaluation

(1) Background: The autologous matrix-induced chondrogenesis (AMIC) is a bio-orthopedic treatment for articular cartilage damage. It combines microfracture surgery with the application of a collagen membrane. The aim of the present study was to report a medium-term follow-up of patients treated with AMIC for focal chondral lesions. (2) Methods: Fourty-eight patients treated surgically and 21 control participants were enrolled in the study. To evaluate the functional outcomes, the proprioceptive (postural stability, postural priority) and isokinetic (peak value of maximum knee extensor and flexor torque in relation to body mass and the total work) measurements were performed. To evaluate the clinical outcomes, the Lysholm score and the IKDC score were imposed. (3) Results: Compared to the preoperative values, there was significant improvement in the first 2 years after intervention in the functional as well as subjective outcome measures. (4) Conclusions: AMIC showed durable results in aligned knees.

Neuromapping of the Capsuloligamentous Knee Joint Structures

Purpose

To investigate neuromuscular electromyographic response of the of the upper and lower leg muscles after the application of an intraoperative, isolated mechanical stimulus of the capsuloligamentous structures, including the anterior (ACL) and posterior cruciate ligaments (PCL), lateral (LM) and medial menisci (MM), plica mediopatellaris (PM), and Hoffa’s fat pat (HFP).

Methods

The electromyographic response of the upper and lower leg muscles (M. rectus femoris; M. vastus medialis; M. semitendinosus; M. biceps femoris; M. gastrocnemius lateralis) of 15 male patients were measured after an isolated mechanical stimulus of the capsuloligamentous structures during an arthroscopic intervention using a customized intraoperative setup. Target parameters were the short (SLR; <30 milliseconds) and medium latency responses (MLR; >30 milliseconds) after the mechanically-induced trigger.

Results

The ACL, PCL, LM, and MM displayed high interindividual reproducibility of >76%. The MM was the only structure indicating both an SLR and MLR for all muscles. Although signals could be detected, there was no reproducibility in electromyographic signal activation for the HFP. The most rapid MLR was observed for the PM (quadriceps: 37 milliseconds).

Conclusions

Each stimulated structure displayed an individual MLR response, which allowed us to create neuromapping combining the anatomical and quantitative representations of the individual muscular activation patterns after isolated mechanical stimulation of the capsuloligamentous knee joint structures, corroborating our hypothesis.

Level of Evidence

Diagnostic - Level II.

Differentiation of the Strength of Back Muscle Contraction Under Fatigue: Does Force Feedback Play a Role?

OBJECTIVE

This study investigates the ability of subjects to differentiate the strength of back muscle contraction with and without feedback information on force produced under fatigue and nonfatigue conditions.

DESIGN

Controlled laboratory study.

SETTING

Research laboratory environment.

PARTICIPANTS

A group of 52 healthy young men participated in the study.

INTERVENTION

Subjects self-estimated 50% of the maximal voluntary isometric contraction of back muscles either on their own volition or on the basis of information about the actual force, before and after the Sørensen fatigue test.

MAIN OUTCOME MEASURES

The force was measured by means of the FiTRO Back Dynamometer.

RESULTS

The self-estimated 50% maximal voluntary isometric contraction was significantly higher than the one calculated from maximal voluntary isometric contraction during 10 trials in 2 repeated sessions (8.3% and 10.0%, P < .05). However, when feedback on the force produced was provided, significantly higher values were observed during an initial trial in both sessions (8.5%, P = .04 and 12.1%, P = .01). Subjects were able to estimate the target force during the following trials. Fatigue induced a decrease in peak force (7.7%, P = .04), whereas the ability to regulate the prescribed force was not compromised. Constant error was lower with than without force feedback during both measurements (2.15% and 6.85%; 3.06% and 8.56%). However, constant and variable errors were greater under fatigue than nonfatigue conditions (8.43% and 5.55%; 0.41% and 0.37%). Similarly, root mean square error decreased with force feedback (from 6.88% to 3.48% and from 8.74% to 5.09%) and increased under fatigue (from 5.87% to 8.67%).

CONCLUSIONS

These findings indicate that force feedback plays a role in the differentiation of the strength of back muscle contraction, regardless of fatigue. It contributes to a more precise regulation of force produced during voluntary isometric contraction of back muscles. This promising method awaits further experimentation to be applied for individuals with low back pain.

Dynamic stretching is not detrimental to neuromechanical and sensorimotor performance of ankle plantarflexors

The acute effects of two dynamic stretching (DS) protocols on changes in the ankle range of motion (RoM), neuromechanical, and sensorimotor properties of the plantarflexor muscle group were examined. Eighteen participants received slow (SDS) or fast dynamic stretching (FDS) on two separate days. Outcome measures were assessed pre- and 2 minutes post-interventions, and included maximum dorsiflexion angle, maximum isometric torque at neutral ankle position, maximum concentric and eccentric torques, force matching capacity, joint position sense and medial gastrocnemius muscle and tendon strain. Possibly and likely small increases in dorsiflexion RoM were observed after SDS (mean ± 90% confidence intervals; 1.8 ± 1.2°) and FDS (2.1 ± 1.2°), respectively. Very likely moderate decreases in muscle strain after SDS (-38.0 ± 20.6%) and possibly small decrease after FDS (-13.6 ± 21.2%) were observed. SDS resulted in a likely beneficial small increase in tendon strain (25.3 ± 29.7%) and a likely beneficial moderate increase after FDS (41.4 ± 44.9%). Effects on strength were inconsistent. Possibly small effect on positional error after SDS (-27.1 ± 37.5%), but no clear effect after FDS was observed. Both DS protocols increased RoM, and this was more due to an increase in tendon elongation rather than the muscle. However, SDS showed greater improvement than FDS in both neuromechanical and sensorimotor performance, and hence, SDS can be recommended as part of warm-up in sporting contexts.

The effect of ankle tape on joint position sense after local muscle fatigue: a randomized controlled trial

Background

Ankle tape is widely used by athletes to prevent ankle sprain. Although there is growing evidence that ankle tape improve joint position sense, but yet it is not clear even if tape improve joint position sense after muscle fatigue, because fatigue impair joint position sense and raise the risk of ankle sprain. The aim of this study is to examine the effect of ankle tape on joint position sense after local muscle fatigue.

Method

This trial is a randomized controlled trial. 34 healthy subjects participated in this trial. Subjects were randomized distributed into two groups: with tape and without tape. Active and passive absolute error and variable error mean values for two target positions of the ankle joint (15° inversions and inversion minus 5°) before and after fatigue protocol consisted of 30 consecutive maximal concentric/concentric contractions of the ankle evertors and invertors. In this trail joint position sense for all subjects was assessed using The Biodex System isokinetic dynamometer 3, this system is used also for fatigue protocol.

Results

For the variable error (VE), significant mean effect was found for active joint position sense in 15° of inversion after muscle fatigue (P < 0, 05). It was a significant decrease in the work in the last third of inversion detected (P < 0, 05). There was no significant main effect found for fatigue index of eversion.

Conclusion

Ankle tape can improve joint position sense at the fatigue session when joint position sense becomes worse. As a result, ankle tape may be useful to prevent ankle sprain during playing sports. We suggest athletes and individuals at risk of ankle sprain to apply taping before high-load activity.

Trial registration

The study was retrospectively registered on the ISRCTN registry with study ID ISRCTN30042335 on 12th December 2017.

Effects of a Short-Term Conditioning Intervention on Knee Flexor Sensorimotor and Neuromuscular Performance in Men

CONTEXT

Long-term conditioning programs for enhanced sensorimotor performance have been causally linked to reduced risk of serious ligamentous injury. However, the efficacy of brief, short-term conditioning interventions has not been established.

OBJECTIVE

To assess the effects of short-term sensorimotor conditioning on the knee flexors.

DESIGN

Randomized controlled trial.

SETTING

University research laboratory.

PARTICIPANTS

23 males randomly assigned to conditioning (n = 12; age: 20.5 ± 1.8 y; height: 1.80 ± 0.05 m; body mass: 74.3 ± 6.0 kg [mean ± SD]) and no-conditioning control (n = 11; age: 20.6 ± 1.9 y; height: 1.79 ± 0.05 m; body mass: 73.6 ± 6.3 kg) groups.

INTERVENTION

Sensorimotor conditioning of the nondominant leg (4 sessions/wk; 3 wk).

MAIN OUTCOME MEASURES

Sensorimotor (blind force and limb-position-replication errors) and neuromuscular (peak force, electromechanical delay [volitional and magnetically evoked]) performance of the knee flexors of both legs were assessed. The contralateral limb and an antecedent period of no conditioning were controls.

RESULTS

The conditioned leg showed decreased force error to 3.8% (3.8 ± 6.9% vs 6.3 ± 3.7% [mean ± SD], post- vs preconditioning, respectively; F_1,21 = 5.4; P = .04) and a trend toward decreased positional error to 2.0% (2.0 ± 6.9% vs 4.7 ± 7.7%, post- vs preconditioning; F_1,21 = 2.7; P = .06). Performances were not altered in the control conditions. Modest improvements were noted for volitional electromechanical delay following conditioning (39.8 ± 4.3 ms vs 42.3 ± 5.2 ms [F_1,21 = 7.2; P = .01]), but peak force (overall, 202 ± 78 N) and magnetically evoked electromechanical delay (24.7 ± 4.2 ms) were not influenced.

CONCLUSION

Short-term conditioning offered improved sensorimotor performance and positively affected neuromuscular determinants of knee flexor performance in men.

Sense of extension force and angle of the knee joint are correlated between two generations of men

Numerous motor abilities depend on the activity of proprioceptors, which has been suggested to be genetically determined. To test this hypothesis, the control of torque generated by knee extensors and knee position was studied in 30 father-son pairs both before and immediately after running. After stabilisation of the participant in a sitting position, the knee joint of his dominant leg was flexed to 90°, and the maximal voluntary torque (MVT) of the dominant knee extensors under static conditions was measured. The participant then tried five times to produce 50% of the MVT. Next, the participant extended the knee to 45° five times without visual control. Significant correlations between the reproducibility of successive trials for groups of fathers and their sons were found. The correlation coefficients for the repeatability of the knee extension torque were 0.69 (confidence interval [CI] = 0.45-0.84; P < 0.01) and 0.75 (CI = 0.54-0.87; P < 0.01) before and after the fatiguing exercise, respectively, whereas the coefficient for the reproducibility of positioning the knee was 0.49 (CI = 0.16-0.72; P < 0.01) after the fatiguing exercise. Our results indicate a significant influence of hereditary factors on the control of limb torque and position.

Rehabilitation Principles of the Anterior Cruciate Ligament Reconstructed Knee: Twelve Steps for Successful Progression and Return to Play

The rehabilitation process begins immediately after injury to the anterior cruciate ligament (ACL). The goal of preoperative rehabilitation is to prepare the patient for surgery. Current rehabilitation programs focus on strengthening exercises and proprioceptive and neuromuscular control drills to provide a neurologic stimulus. It is also important to address preexisting factors, especially for the female athlete, that may predispose to future injury, such as hip and hamstring weakness. Our goal in the rehabilitation program is to restore full, unrestricted function and to assist the patient to return to 100% of the preinjury level while achieving excellent long-term outcomes.

The response of the autonomic nervous system to passive lower limb movement and gender differences

The aim of the present study was to identify the response of the autonomic nervous system (ANS) to passive lower limb movement and to determine whether there are gender differences. The experimental sets included 5 cycles per minute (CPM5), 10 cycles per minute (CPM10) and 15 cycles per minute (CPM15) on the passive cycling machine. ANS activity was measured using heart rate variability time domain analysis (RR interval, pNN50, RMSSD and SDNN), frequency domain analysis (TF, LF, HF and LF/HF) and Poincaré plot analysis (SD1, SD2 and SD1/SD2 ratio). The collected signal at rest served as the baseline (rest). Compared with the parameters at rest, the male subjects had decreased pNN50, decreased SDNN, lower TP and LF power (ms(2)), suppressed LF (n.u.), augmented HF (n.u.), suppressed LF/HF, decreased SD2 and increased SD1/SD2 ratios in response to CPM5 or CPM10 (all P < 0.05). Compared with the parameters at rest, decreased LF/HF and increased SD1/SD2 in response to CPM5 or CPM10 (all P < 0.05) were the only changes in the female subjects. LF/HF and SD1/SD2 differed between both groups for the same level of passive lower limb movement (all P < 0.05). These results suggest that passive lower limb movement leads to an ANS response and that male subjects are more sensitive to passive lower limb movements. During passive leg movements, sympathetic nervous activity is largely suppressed, and vagal activity achieves dominance. The response of the ANS to passive leg movement is determined by gender.

Comparison of landing biomechanics between male and female dancers and athletes, part 2: Influence of fatigue and implications for anterior cruciate ligament injury

BACKGROUND

Fatigue is strongly linked to an increased risk of injuries, including anterior cruciate ligament (ACL) ruptures. Part 1 of this study identified differences in the biomechanics of landing from a jump between dancers and team athletes, particularly female athletes, which may explain the epidemiological differences in ACL injuries between dancers and team athletes and the lack of a sex disparity within dancers. However, it is not known if these biomechanical variables change differently between team athletes and dancers in the face of fatigue. PURPOSE/ HYPOTHESIS: The purpose of this study was to compare dancers' and team athletes' resistance to fatigue and its effect on the biomechanics of single-legged drop landings. The primary hypotheses were that dancers may be more resistant than team athletes to the onset of fatigue and/or may have different biomechanical responses than athletes in landing tasks once fatigue has been achieved.

STUDY DESIGN

Controlled laboratory study.

METHODS

Kinematics and kinetics were recorded as 40 elite modern and ballet dancers (20 men and 20 women) and 40 team sport athletes (20 men and 20 women; National Collegiate Athletic Association Division I-III) performed single-legged drop landings from a 30-cm platform before and after a fatigue protocol consisting of step-ups and vertical jumps. Unfatigued and fatigued joint kinematics and kinetics were compared between groups and sexes with multivariate analyses of variance, followed by pairwise t tests as appropriate.

RESULTS

Dancers took longer (P = .023) than team athletes to reach a similar state of fatigue. Multiple kinetic (eg, increased peak knee valgus moment; P < .001) and kinematic (eg, increased lateral and forward trunk flexion; P < .001 and P = .002, respectively) parameters of landing changed with fatigue, such that both fatigued dancers and athletes landed with mechanics that were more at risk for ACL injuries as compared with before fatigue.

CONCLUSION

Dancers took significantly longer to reach fatigue than team athletes. Female athletes consistently exhibited landing patterns associated with a risk for ACL injuries when compared with the other 3 groups. Fatigue changed landing mechanics similarly in both dancers and athletes, such that all groups landed with worse alignment after being fatigued.

CLINICAL RELEVANCE

Dancers are more resistant to lower extremity fatigue than athletes, and this may partially explain the lower incidence of ACL injuries in both male and female dancers compared to team athletes. The extensive training in landing technique and daily practice that dancers undergo from a young age may be responsible for the higher levels of endurance.

The effect of repetitive passive and active movements on proprioception ability in forearm supination

[Purpose] This study was conducted in order to investigate the effect of repetitive passive movement and repetitive active movement on proprioception in forearm supination. [Subjects] This study had a cross-sectional design. Twenty-three right-handed healthy subjects were recruited. All subjects randomly received both repetitive passive movement and repetitive active movement (repetitive passive/active movement at 120°/s with 60 repetitions over a 0–80° range). Active and passive joint repositioning of all subjects was measured using the error score for position sense, both before and after repositioning intervention. [Results] In the repetitive passive movement test, there was a statistically significant decrease in the pre- versus post-repositioning error scores in the active and passive angle examinations. In the repetitive active movement test, there was a statistically significant increase in pre- versus post-repositioning error scores in the active and passive angle examinations. In the comparison of position sense, there was a statistically significant decrease in both active and passive angle repositioning error scores in repetitive passive movement versus repetitive active movement. [Conclusion] Repetitive passive movement improved the proprioception results for forearm supination, compared to repetitive active movement. Results of this study indicate that repetitive passive movement can be recommended to clinicians for rehabilitation therapy as it provides greater proprioception benefits.

The differential effects of PNF versus passive stretch conditioning on neuromuscular performance

The effects of flexibility conditioning on neuromuscular and sensorimotor performance were assessed near to full knee extension (25°). Eighteen males who were randomly assigned into two groups underwent eight weeks (three-times per week) of flexibility conditioning (hip region/knee flexor musculature; dominant limb) involving either proprioceptive neuromuscular facilitation (PNF) (n=9) or passive stretching (PASS) (n=9). Both modes of flexibility conditioning are popular within contemporary exercise and clinical settings and have demonstrated efficacy in improving range of motion. The contralateral limb and a prior 'no exercise' condition were used as controls. The PNF and PASS modes of conditioning improved passive hip flexibility to a similar extent (mean 19.3% vs. baseline, intervention limb, p<0.01) but did not alter knee flexor strength (overall mean 309.6±81 N) or sensorimotor performance (force and positional errors: 2.3±8.2% and 0.48±7.1%). Voluntary and magnetically evoked electromechanical delays (EMDV and EMDE, respectively) were increased but to a greater extent following PASS compared to PNF (PASS: 10.8% and 16.9% lengthening of EMDV and EMDE, respectively vs. PNF: 3.2% and 6.2%, p<0.01).The attenuated change to electromechanical delay (EMD) performance during PNF conditioning suggests a preserved capability for rapid muscle activation, which is important in the maintenance of dynamic joint stability. That PNF was also equally efficacious in flexibility conditioning would suggest that this mode of flexibility training should be used over passive to help preserve dynamic joint stability capabilities at this extended and vulnerable joint position.

How much of the PCL is really preserved during the tibial cut?

PURPOSE

There are two different techniques for retaining the posterior cruciate ligament (PCL) in total knee arthroplasty. The attachment of the PCL can be spared during resection of the tibial plateau, so that a small posterior bone block remains. In contrast to this, many surgeons resect the tibial plateau completely and detach a part of the tibial PCL attachment from the resected material. The objective of this study was to determine how big this part is in an anatomical resection of the tibial plateau with 0° and 7° slope and whether it is gender-dependent.

METHODS

Two hundred consecutive patients who had undergone MRI of a knee joint were included. Patients were excluded if they were younger than 18 years or had dysplasia of the knee joint or injuries of the posterior cruciate ligament. The MRIs of 182 knees that fulfilled the inclusion criteria were analysed. For each knee, an anatomical tibial resection with 0° and 7° posterior slope was simulated, and the parts of the tibial PCL attachment that were resected and retained were determined.

RESULTS

Given a measured tibial resection with 0° slope, 45 ± 28% of the tibial PCL attachment was removed in the men, compared with 46 ± 30% in the women (n.s.). Given a resection with 7° slope, 69 ± 24% of the tibial PCL attachment was removed in the men and 67 ± 25% in the women. This corresponded to a complete resection in 19 men (20%) and 16 women (24%).

CONCLUSIONS

Independently of gender, the anatomical resection of the tibia leads to the removal of a considerable part of the tibial PCL attachment, if this is not spared in the form of a bone block during resection. This becomes increasingly relevant with higher posterior slope of the resection plane. In the case of a cruciate-retaining surgical technique, the retention of the posterior tibial cortical bone in the area of attachment of the PCL is therefore strongly recommended.

LEVEL OF EVIDENCE

II.

Recent advances in the rehabilitation of anterior cruciate ligament injuries

Rehabilitation following anterior cruciate ligament surgery continues to change, with the current emphasis being on immediate weight bearing and range of motion, and progressive muscular strengthening, proprioception, dynamic stability, and neuromuscular control drills. The rehabilitation program should be based on scientific and clinical research and focus on specific drills and exercises designed to return the patient to the desired functional goals. The goal is to return the patient's knee to homeostasis and the patient to his or her sport or activity as safely as possible. Unique rehabilitation techniques and special considerations for the female athlete will also be discussed. The purpose of this article is to provide the reader with a thorough scientific basis for anterior cruciate ligament rehabilitation based on graft selection, patient population, and concomitant injuries.

Rapid repetitive passive movement improves knee proprioception

BACKGROUND

Proprioception can be affected by many factors including exercise. Most exercises involve certain degrees of repeated passive movements, and different velocities of these movements might affect proprioception differently. The purpose of this study was to evaluate the influences of different angular velocities of repeated passive movement on knee proprioception via active repositioning and kinesthesia measurement.

METHODS

A quasi-experimental design with repeated measure on movement velocity (0°/s, 2°/s, 90°/s, and 150°/s). Sixteen healthy young adults participated in the study. All of them received 30 times repeated passive knee movement intervention in four different knee angular velocities - 0°/s, 2°/s, 90°/s, and 150°/s - with counter-balanced sequence in four successive days. Knee active repositioning and kinesthesia were measured with error scores before and after the intervention.

FINDINGS

The results revealed a decrease in error scores in both active repositioning and kinesthesia measurement with the velocities of 90°/s and 150°/s (p<0.05); however no significant change was seen with the static condition (0°/s ) or with the velocity of 2°/s.

INTERPRETATION

We concluded that repeated passive movement with rapid angular velocities was capable of improving knee proprioception, specifically in active repositioning and kinesthesia measurements. These results would provide information on the effects of different movement velocities onto knee proprioception. Along with further investigations, the findings could potentially enhance our knowledge on knee injury prevention, treatment, and rehabilitation.

Effects of active fatiguing movement versus passive repetitive movement on knee proprioception

BACKGROUND

Proprioception can be affected by many factors such as age, gender, injury, disease, exercise, and fatigue. To date, the mechanisms or pathways by which fatigue influences proprioception have not been elucidated. Generally, it is accepted that local muscular effects occurred during fatigue state may negatively affect proprioception. Research has indicated that metabolic acidosis resulting from active muscle activities, along with tissue stretching and joint laxity resulting from repetitive joint movements, are likely related to proprioceptive deterioration. So far, little direct evidence or research supports these statements. The purpose of this study was to examine the effects of fatigue exercises (repetitive active movement) and repetitive passive movements on knee proprioception.

METHODS

A quasi-experimental design with repeated measure on proprioception following two forms of knee joint movement (repetitive active/passive movement in 120 degrees /s with 60 repetitions over a 10 degrees -100 degrees range) was conducted. Fifteen healthy volunteers underwent two forms of movement intervention in two consecutive days in a counter-balanced manner. Knee joint repositioning errors were measured before and after the movement intervention.

FINDINGS

Study results showed a statistically significant increase in absolute repositioning error following repetitive active movement, but a decrease following repetitive passive movement intervention.

INTERPRETATION

This study concluded that a repetitive passive movement protocol was capable of improving knee joint position sense. Meanwhile, the negative effect from the muscle receptors following the repetitive active movement overwhelmed the positive effect from the repetitive passive movement intervention. It supports the clinical utilization of repetitive passive movement to promote proprioception. This utilization can be implemented for proprioceptive training in sports activities, plus injury prevention and rehabilitation.

Quadriceps and hamstrings fatigue alters hip and knee mechanics

Neuromuscular fatigue exacerbates abnormal landing strategies, which may increase noncontact anterior cruciate ligament (ACL) injury risk. The synergistic actions of quadriceps and hamstrings (QH) muscles are central to an upright landing posture, though the precise effect of simultaneous fatigue of these muscles on landing and ACL injury risk is unclear. Elucidating neuromechanical responses to QH fatigue thus appears important in developing more targeted fatigue-resistance intervention strategies. The current study thus aimed to examine the effects of QH fatigue on lower extremity neuromechanics during dynamic activity. Twenty-five healthy male and female volunteers performed three single-leg forward hops onto a force platform before and after QH fatigue. Fatigue was induced through sets of alternating QH concentric contractions, on an isokinetic dynamometer, until the first five repetitions of a set were performed at least 50% below QH peak torque. Three-dimensional hip and knee kinematics and normalized (body mass x height) kinetic variables were quantified for pre- and postfatigue landings and subsequently analyzed by way of repeated- measures mixed-model ANOVAs. QH fatigue produced significant increases in initial contact (IC) hip internal rotation and knee extension and external rotation angles (p < .05), with the increases in knee extension and external rotation being maintained at the time of peak vertical ground reaction force (vGRF) (p < .05). Larger knee extension and smaller knee flexion and external rotation moments were also evident at peak vGRF following fatigue (p < .05). Females landed with greater hip flexion and less abduction than males at both IC and peak vGRF as well as greater knee flexion at peak vGRF (p < .05). The peak vGRF was larger for females than males (p < .05). No sex x fatigue effects were found (p > .05). Fatigue of the QH muscles altered hip and knee neuromechanics, which may increase the risk of ACL injury. Prevention programs should incorporate methods aimed at countering QH fatigue.

Effects of fatigue due to contraction of evertor muscles on the ankle joint position sense in male soccer players

BACKGROUND

The high incidence of ankle sprains that occur later in matches suggests that fatigue may contribute to altered neuromuscular control of the ankle. Moreover, deficits in ankle joint position sense (JPS) were seen in patients with a history of recurrent ankle sprains. It has been hypothesized that ankle sprains may be related to altered ankle JPS as a consequence of fatigue.

PURPOSE

To evaluate if fatiguing contractions of evertor muscles alter the ankle JPS.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-six soccer players (age, 24.7 +/- 1.3 years; height, 183.7 +/- 8.2 cm; weight, 78.9 +/- 7.9 kg) were recruited. Subjects were asked to recognize 2 positions (15 degrees of inversion and maximal active inversion minus 5 degrees ) for 2 conditions: normal and fatigue. Muscular fatigue was induced in evertor muscles of the dominant leg by using isometric contractions. The average of the absolute and variable errors of 3 trials were recorded for both fatigue and nonfatigue conditions. A matched control group of 36 soccer players (age, 23.9 +/- 0.9 years; height, 181.2 +/- 6.9 cm; weight, 77.8 +/- 6.5 kg) was asked to recognize the same positions, before a soccer match and after 45 minutes of playing, and their same scores were recorded. Finally, results of the 2 groups were compared.

RESULTS

There was significant decrease in subjects' ability to recognize passive and active repositioning of their ankle after a fatigue protocol (P <.001). Passive and active JPS were reduced after playing (P <.001). There was no significant difference between 2 groups in the results of JPS before and after the intervention (P > .1).

CONCLUSION

The acuity of the ankle JPS is reduced subsequent to a fatigue protocol and after a soccer match.

CLINICAL RELEVANCE

Evaluation of athletes' ankle JPS before returning to physical activity may prevent further injuries.

Fatigue alters lower extremity kinematics during a single-leg stop-jump task

To examine the kinematic characteristics of the hip and knee during a single-leg stop-jump task before and after exercise-to-fatigue, and to determine if the fatigue response is gender-dependent. Lower extremity kinematic measurements were taken of male and female subjects while they performed a sports functional task before and after fatigue developed from exhaustive running. Thirty healthy, physically active subjects (15 males and 15 females) Knee and hip joint kinematics were calculated utilizing three-dimensional video analysis. Each subject performed five single-leg stop-jumps before and after an exercise-to-fatigue bout. All subjects underwent a fatigue protocol using the modified Astrand protocol. Fatigue was verified using the Rating of Perceived Exertion along with the subject's heart rate. All data were analyzed using two factor (test x gender) repeated measures ANOVA (P<0.05). Both males and females demonstrated significantly less maximal knee valgus (P=0.038) and decreased knee flexion at initial contact (P=0.009) post-fatigue. No significant differences were identified in hip joint angles between sessions or between sexes. The results show that fatigue developed from exhaustive running alters lower extremity kinematics during a single-leg stop-jump task. The more neutral position in the frontal plane might be an effort to protect the knee. The decrease in knee flexion at initial contact may be an attempt to increase knee stability following fatigue. Our results did not reveal any gender differences in this specific task.

Combined effects of fatigue and decision making on female lower limb landing postures: central and peripheral contributions to ACL injury risk

BACKGROUND

In spite of ongoing prevention developments, anterior cruciate ligament injury rates and the associated sex-disparity have remained, suggesting an incomplete understanding of the injury mechanism. While both fatigue and decision making are known in isolation to directly impact anterior cruciate ligament injury risk, their combined manifestations remain unknown. We thus examined the combined effects of fatigue and decision making on lower limb kinematics during sports relevant landings.

METHODS

Twenty five female National College Athletic Association athletes had initial contact and peak stance phase 3D lower limb joint kinematics quantified during anticipated and unanticipated single (left and right) leg landings, both before and during the accumulation of fatigue. Jump direction was governed by light stimuli activated prior to and during the pre-land phase of respective anticipated and unanticipated trials. To induce fatigue, subjects performed repetitive squat (n=5) and randomly ordered jump sequences, until squats were no longer possible. Subject-based measures of each dependent factor were then calculated across pre-fatigue trials, and for those denoting 100% and 50% fatigue, and submitted to a 3-way mixed design analysis of covariance to test for the main effects of fatigue time, decision and leg.

FINDINGS

Fatigue caused significant increases in initial contact hip extension and internal rotation, and in peak stance knee abduction and internal rotation and ankle supination angles. Fatigue-induced increases in initial contact hip rotations and in peak knee abduction angle were also significantly more pronounced during unanticipated compared to anticipated landings.

INTERPRETATION

The integrative effects of fatigue and decision making may represent a worst case scenario in terms of anterior cruciate ligament injury risk during dynamic single leg landings, by perpetuating substantial degradation and overload of central control mechanisms.

Impact of fatigue on gender-based high-risk landing strategies

PURPOSE

Noncontact anterior cruciate ligament (ACL) injuries carry significant short- and long-term morbidity, particularly in females. To combat this epidemic, neuromuscular training has evolved aimed at modifying high-risk lower-limb biomechanics. However, injury rates and the gender disparity in these rates remain, suggesting that key components of the injury mechanism continue to be ignored. This study examined the potential contributions of neuromuscular fatigue to noncontact ACL injuries.

METHODS

Ten male and 10 female NCAA athletes had 3D lower-limb-joint kinematics and kinetics recorded during 10 drop jumps, both before and after fatigue. Mean subject-based initial-contact (N = 9) and peak stance-phase kinematic (N = 9) and normalized (mass x height) kinetic (N = 9) parameters were quantified before and after fatigue and submitted to a three-way ANOVA to determine for the main effects of leg, gender, and fatigue. A Bonferroni corrected alpha level of 0.002 was adopted for all statistical comparisons.

RESULTS

Females landed with more initial ankle plantar flexion and peak-stance ankle supination, knee abduction, and knee internal rotation compared with men. They also had larger knee adduction, abduction, and internal rotation, and smaller ankle dorsiflexion moments. Fatigue increased initial and peak knee abduction and internal rotation motions and peak knee internal rotation, adduction, and abduction moments, with the latter being more pronounced in females.

CONCLUSIONS

Fatigue-induced modifications in lower-limb control may increase the risk of noncontact ACL injury during landings. Gender dimorphic abduction loading in the presence of fatigue also may explain the increased injury risk in women. Understanding fatigue effects at both the central and peripheral levels will further afford elucidation of the ACL injury mechanism and, hence, more successful prevention strategies.

Effect of exercise-induced fatigue on position sense of the knee in the elderly

Previously, data on the effects of muscle fatigue on joint position sense (JPS) have been provided. However, to our knowledge, no studies have been conducted so far to assess the effects of local muscle fatigue on elderly proprioception. Thus, the purpose of the present study was to determine the effects of local muscle fatigue on knee JPS in old-age-subjects. Sixteen male volunteers (mean age +/- SD: 69.81 +/- 3.92 years) participated in this study. Each subject completed all of the data collection in one morning session; JPS measures were obtained prior to and immediately after the fatigue protocol. JPS was evaluated by the technique of open-kinetic chain and active knee positioning, and was reported using absolute, relative and variable angular errors. The fatigue protocol applied to the lower extremity consisted of 30 maximum concentric repetitions of the knee extensors and flexors muscles on an isokinetic dynamometer at an angular velocity of 120 s(-1) (2.09 rad s(-1)). The results showed that peak torque of knee extensor and flexor muscles was significantly decreased from rest to post exercise-induced fatigue. After local load to the knee muscles, a significant increase of absolute angular error was observed (2.56 degrees ). The relative error showed the directional bias in the extension movement. However, the reliability and accuracy of estimating knee angles as showed by the variable error is similar at both times. It can be concluded that exercise-induced local muscle fatigue alters knee JPS in old age adults.

The anterior cruciate ligament deficiency as a model of brain plasticity

This paper describes a plausible mechanism for the development of brain plastic changes due to a peripheral joint injury, such as anterior cruciate ligament (ACL) rupture. Evidence for the hypothesis is based on mainly three indications derived from the literature review: (a) the existence of two different categories of ACL patients, the copers and non-copers, presenting different features of functional deficiencies, (b) the demand of a sufficient post-traumatic time (more than 6 months) for the dysfunction development and (c) the fact that the dysfunction is not limited to the injured limb but also concerns the non-injured one. Considering the fact that ACL contains mechanoreceptors, which inform the central nervous system (CNS) about joint sense position and kinaesthesia, it can be suggested that this kind of injury might be regarded as a neurophysiological dysfunction, not being a simple musculoskeletal injury. The rupture of the ACL could lead to the cessation/depletion or differentiation of the ascending afferent pathway from the injured joint towards CNS, inducing to the joint de-afferentation and consequently CNS reorganization and joint de-efferentation. In case of presumable evidence of the proposed hypothesis, its clinical application could concern several aspects of the intervention procedures. For example, a number of clinical findings, such as the functional differences presented between two separate clinical groups of patients (copers and non-copers) could be justified or the rehabilitation strategies might have to be revised, provided that certain therapeutic components have influence on facilitating brain plastic changes that induce to beneficial functional outcomes.

Sustained muscle activity minimally influences dynamic position sense of the ankle

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

The purpose of this study was to determine if a sustained fatiguing contraction of the dorsiflexor muscles alters the dynamic position sense (proprioception) and the associated central nervous system processing time of information from the ankle.

BACKGROUND

Ankle injury has been hypothesized to be related to altered proprioception as a consequence of fatiguing exercise. Previous reports assessing proprioception include tests of motor performance (balance and limb repositioning) or tests of a joint under static conditions. This study used a novel experimental approach to test the effects of exercise on the somatosensory system of the ankle.

METHODS AND MEASURES

Nineteen healthy subjects were tested on their ability to extend the metacarpophalangeal joint of their left index finger when their left ankle was passively plantar flexed (0 degrees-40 degrees, 10 velocities) through a predetermined target angle (20 degrees). Testing occurred before and after a fatiguing contraction of the dorsiflexor muscles.

RESULTS

Subjects accurately indicated the ankle target angle up to ankle velocities of 70 degrees/s (300 ms) both before and after the sustained fatiguing contraction. At velocities above 70 degrees/s all subjects could no longer scale to accurately indicate the target angle with the index finger and consequently overshot the target. The central nervous system processing time was estimated to be approximately 85 milliseconds before and after the sustained contraction.

CONCLUSIONS

These results indicate that a sustained activity of the dorsiflexion muscles of the ankle minimally affects dynamic position sense and the ability to process dynamic position sense information. Understanding the impact of exercise on sensory system processing will be integral to establishing the scientific basis for rehabilitation programs that purport to train proprioception.

The effect of short-duration sub-maximal cycling on balance in single-limb stance in patients with anterior cruciate ligament injury: a cross-sectional study

Background

It has previously been shown that an anterior cruciate ligament (ACL) injury may lead to impaired postural control, and that the ability to maintain postural control is decreased by fatigue in healthy subjects. To our knowledge, no studies have reported the effect of fatigue on postural control in subjects with ACL injury. This study was aimed at examining the effect of fatigue on balance in single-limb stance in subjects with ACL injury, and to compare the effects, and the ability to maintain balance, with that of a control group of uninjured subjects.

Methods

Thirty-six patients with unilateral, non-operated, non-acute ACL injury, and 24 uninjured subjects were examined with stabilometry before (pre-exercise) and immediately after (post-exercise) short-duration, sub-maximal cycling. In addition, the post-exercise measurements were compared, to evaluate the instantaneous ability to maintain balance and any possible recovery. The amplitude and average speed of center of pressure movements were registered in the frontal and sagittal planes. The paired t-test was used for the intra-group comparisons, and the independent t-test for the inter-group comparisons, with Bonferroni correction for multiple comparisons.

Results

No differences were found in the effects of exercise between the patients and the controls. Analysis of the post-exercise measurements revealed greater effects or a tendency towards greater effects on the injured leg than in the control group. The average speed was lower among the patients than in the control group.

Conclusions

The results of the present study showed no differences in the effects of exercise between the patients and the controls. However, the patients seemed to react differently regarding ability to maintain balance in single-limb stance directly after exercise than the control group. The lower average speed among the patients may be an expression of different neuromuscular adaptive strategies than in uninjured subjects.

The effect of local and general fatigue on knee proprioception

PURPOSE

The purpose of this study was to compare the effects of local and general fatigue loads on knee proprioception.

TYPE OF STUDY

Experimental controlled study.

METHODS

Proprioception of the knee joint was evaluated by measuring absolute angular error (AAE) at matching defined index angles before and after 2 different types of fatigue protocols (local load and general load) in 27 healthy male volunteers. Local load was provided with maximum isokinetic knee flexion-extension on the isokinetic dynamometer, and general load was 5 minutes running on a treadmill.

RESULTS

After local load, a significant decrease in peak torque of knee flexors and extensors was found, but no significant change in AAE was seen. In contrast, after general load, a significant increase of AAE was noted without significant muscle weakness.

CONCLUSIONS

The different results in previous studies evaluating the effect of fatigue on knee proprioception may have been affected by the difference of fatigue protocols, whether local or general load. Although local load was intended to produce local fatigue of the knee, which may cause dysfunction of muscle mechanoreceptors, general load may have produced general fatigue and affected other mechanisms in the proprioceptional pathway. The results of the present study suggest that decreased reproduction ability after general load is not due to the loss of peripheral afferent signals, but to other factors, especially deficiency of central processing of proprioceptive signals.

CLINICAL RELEVANCE

To prevent knee injury caused by fatigue-induced proprioceptional decline, muscle endurance training alone is not enough, and neuromuscular training, including central motor programming, is essential.

Effects of short-term cycling on knee joint proprioception in healthy young persons

BACKGROUND

Criteria are needed for measuring the effects of exercise and fatigue on proprioception.

PURPOSE

To measure knee joint proprioception in healthy subjects before and after exercise and to establish a reference for further comparisons of patients with knee injuries.

STUDY DESIGN

Controlled laboratory study.

METHODS

We tested proprioception in the knees of 24 healthy subjects with a mean age of 24 years and median Tegner score of 5. Subjects were tested to estimate their thresholds for detecting slow passive motion, from starting positions of 20 degrees and 40 degrees before and after cycling on an ergometer bicycle until the pulse rate reached a steady state level and they reached a score of 14 to 17 on Borg's Ratio of Perceived Exertion scale.

RESULTS

After cycling, significantly higher threshold values were found for perception of movement toward flexion from both 20 degrees and 40 degrees. No significant differences were seen in measurements of movement toward extension.

CONCLUSIONS

Knee joint proprioception seems to be impaired by exercise or training.

CLINICAL RELEVANCE

This impairment may lead to defective dynamic stabilization of the joint, leading to an increased risk of injuries.

Balance in single-limb stance in healthy subjects--reliability of testing procedure and the effect of short-duration sub-maximal cycling

BACKGROUND

To assess balance in single-limb stance, center of pressure movements can be registered by stabilometry with force platforms. This can be used for evaluation of injuries to the lower extremities. It is important to ensure that the assessment tools we use in the clinical setting and in research have minimal measurement error. Previous studies have shown that the ability to maintain standing balance is decreased by fatiguing exercise. There is, however, a need for further studies regarding possible effects of general exercise on balance in single-limb stance. The aims of this study were: 1) to assess the test-retest reliability of balance variables measured in single-limb stance on a force platform, and 2) to study the effect of exercise on balance in single-limb stance, in healthy subjects.

METHODS

Forty-two individuals were examined for test-retest reliability, and 24 individuals were tested before (pre-exercise) and after (post-exercise) short-duration, sub-maximal cycling. Amplitude and average speed of center of pressure movements were registered in the frontal and sagittal planes. Mean difference between test and retest with 95% confidence interval, the intraclass correlation coefficient, and the Bland and Altman graphs with limits of agreement, were used as statistical methods for assessing test-retest reliability. The paired t-test was used for comparisons between pre- and post-exercise measurements.

RESULTS

No difference was found between test and retest. The intraclass correlation coefficients ranged from 0.79 to 0.95 in all stabilometric variables except one. The limits of agreement revealed that small changes in an individual's performance cannot be detected. Higher values were found after cycling in three of the eight stabilometric variables.

CONCLUSIONS

The absence of systematic variation and the high ICC values, indicate that the test is reliable for distinguishing among groups of subjects. However, relatively large differences in an individual's balance performance would be required to confidently state that a change is real. The higher values found after cycling, indicate compensatory mechanisms intended to maintain balance, or a decreased ability to maintain balance. It is recommended that average speed and DEV 10; the variables showing the best reliability and effects of exercise, be used in future studies.

Recent advances in the rehabilitation of isolated and combined anterior cruciate ligament injuries

The rehabilitation process begins immediately following ACL injury, with emphasis on reducing swelling and inflammation; improving motion; regaining quadriceps control; allowing immediate weight-bearing; and restoring full passive knee extension and, gradually, flexion. The goal of preoperative rehabilitation is to prepare the patient mentally and physically for surgery. Once the ACL surgery is performed, it is important to alter the rehab program based on the type of graft used and any concomitant procedures performed. This will aid in preventing several postoperative complications, such as loss of motion, patellofemoral pain, graft failure, and muscular weakness. The goal of this article has been to provide an overview of the application and the scientific basis for formulating a rehabilitation protocol following ACL surgery. For an athlete to return to competition, it is imperative that he or she regain muscular strength and neuromuscular control in their injured leg while maintaining static stability. In the past, rehabilitation programs attempted to prepare the athlete for return to sports by using resistance exercise alone. Current rehabilitation programs focus not only on strengthening exercises, but also on proprioceptive and neuromuscular control drills in order to provide a neurologic stimulus so that the athlete can regain the dynamic stability needed in athletic competition. We believe that it is important to use this approach not only possible causes that might predispose the individual to future injury.

Proprioceptive training and prevention of anterior cruciate ligament injuries in soccer

This commentary describes a program developed to help reduce the incidence of anterior cruciate ligament injuries in soccer players. The basic principles underlying the injury prevention protocol are described with respect to the proprioceptive control mechanisms at the knee joint. This is followed by a detailed description of the program.

Proprioceptive impairment in knee osteoarthritis

Proprioception, the perception of limb position in space, is derived from afferent signals originating primarily from musculotendinous and joint receptors. Proprioception is critical to the maintenance of joint stability. Studies have demonstrated that proprioception is less accurate in patients with knee osteoarthritis versus elderly control subjects, in healthy older versus younger subjects, and in the setting of other conditions affecting the knee including anterior cruciate ligament deficiency and hypermobility syndrome. Possible pathways between proprioceptive inaccuracy, knee osteoarthritis, and related knee disorders are described.