The capacity of the human iliotibial band to store elastic energy during running

Stretch tolerance and elastic passive reaction of the quadriceps femoris seem to depend more on the fascia profundis taut surfaces than on the underlying stretched muscle

The rectus femoris and its covering, the fascia lata (i.e., fascia profundis), are two anatomical structures involved in anterior thigh stretching. This study aimed to identify the role of strain changes in the fascia lata in limiting stretch tolerance. The reaction force intensity of 11 men and 5 women was assessed during passive stretching of the anterior thigh at 130, 110, 90, and 70° of knee flexion. Recent data suggest that the fascia lata strain field is modified with knee flexion. Therefore, the relationship between knee flexion angle and stretch tolerance was assessed. We found that the reaction force of the anterior thigh increased almost linearly with the degree of knee extension between 130° and 70°. The fascia lata stretched surface proprioceptive information seems responsible for stretch tolerance. Fascia profundis strain field must be considered during stretching experiments.

Comparative physiological anthropogeny: exploring molecular underpinnings of distinctly human phenotypes

Anthropogeny is a classic term encompassing transdisciplinary investigations of the origins of the human species. Comparative anthropogeny is a systematic comparison of humans and other living nonhuman hominids (so-called "great apes"), aiming to identify distinctly human features in health and disease, with the overall goal of explaining human origins. We begin with a historical perspective, briefly describing how the field progressed from the earliest evolutionary insights to the current emphasis on in-depth molecular and genomic investigations of "human-specific" biology and an increased appreciation for cultural impacts on human biology. While many such genetic differences between humans and other hominids have been revealed over the last two decades, this information remains insufficient to explain the most distinctive phenotypic traits distinguishing humans from other living hominids. Here we undertake a complementary approach of "comparative physiological anthropogeny," along the lines of the preclinical medical curriculum, i.e., beginning with anatomy and considering each physiological system and in each case considering genetic and molecular components that are relevant. What is ultimately needed is a systematic comparative approach at all levels from molecular to physiological to sociocultural, building networks of related information, drawing inferences, and generating testable hypotheses. The concluding section will touch on distinctive considerations in the study of human evolution, including the importance of gene-culture interactions.

Stretching and Releasing of Iliotibial Band Complex in Patients with Iliotibial Band Syndrome: A Narrative Review

Iliotibial band syndrome (ITBS) is one of the most common overuse syndromes causing knee pain; it is especially prevalent in runners and also common in cyclists, rowers, and field athletes, with occasional cases occurring in non-athletes too. ITBS symptoms can negatively affect not only knee function, but also mental and physical aspects of health-related quality of life. Although various conservative treatment options have been investigated and discussed, there is still no consensus on a standard of care for ITBS. Moreover, the literature on the etiology and risk factors of ITBS, which could help in selecting appropriate treatment methods, is conflicting and inconclusive. The role of individual treatment modalities such as stretching and releasing techniques has not been extensively studied and remains unclear. In this article, we will critically review the available evidence for the benefits of ITB stretching and "release" methods in the treatment of ITBS. In addition to the direct evidence (clinical studies examining the effects of ITB stretching and other methods that purportedly stretch or "release" the ITB), we present several additional lines of reasoning that discuss the rationale for ITB stretching/releasing in terms of the etiology of ITBS, the mechanical properties and behavior of the ITB, and the risk factors for ITBS development. We conclude that the current literature provides some evidence for the inclusion of stretching or other "release" methods in the early rehabilitation of ITBS. Long-term interventions typically include ITB stretching; however, it remains unclear to what extent stretching within a multimodal treatment actually contributes to resolving the symptoms. At the same time, there is no direct evidence to suggest that stretching and "release" methods have any negative effects.

Effects of Running Speeds and Exhaustion on Iliotibial Band Strain during Running

Background: Iliotibial band syndrome (ITBS) is one of the most prevalent overuse injuries in runners. The strain rate in the iliotibial band (ITB) has been theorized to be the primary causative factor in the development of ITBS. Running speed and exhaustion might lead to an alteration in the biomechanics that influence the strain rate in the iliotibial band. Objectives: To identify how exhaustion states and running speeds affect the ITB strain and strain rate. Methods: A total of 26 healthy runners (including 16 males and 10 females) ran at a normal preferred speed and a fast speed. Then, participants performed a 30 min exhaustive treadmill run at a self-selected speed. Afterward, participants were required to run at similar speeds to those of the pre-exhaustion state. Results: Both the exhaustion and running speeds were revealed to have significant influences on the ITB strain rate. After exhaustion, an increase of approximately 3% in the ITB strain rate was observed for both the normal speed (p = 0.001) and the fast speed (p = 0.008). Additionally, a rapid increase in the running speed could lead to an increase in the ITB strain rate for both the pre- (9.71%, p = 0.000) and post-exhaustion (9.87%, p = 0.000) states. Conclusions: It should be noted that an exhaustion state could lead to an increase in the ITB strain rate. In addition, a rapid increase in running speed might cause a higher ITB strain rate, which is proposed to be the primary cause of ITBS. The risk of injury should also be considered due to the rapid increase in the training load involved. Running at a normal speed in a non-exhaustive state might be beneficial for the prevention and treatment of ITBS.

Distinct displacement of the superficial and deep fascial layers of the iliotibial band during a weight shift task in runners: An exploratory study

Motion of the fascial layers of the iliotibial band (ITB), as a reinforcement of the deep fascia lata, is likely to be relevant for its function and mechanical behaviour. This exploratory study aimed to evaluate the ITB fascial layers displacement during a weight shift task. Thirteen pain-free runners performed a 6-second standing weight shift task. B-mode ultrasound imaging using an automated fascicle tracking algorithm was used to measure proximal and distal displacement of superficial and deep ITB layers at the middle region. To study the potential contributors to individual variation of fascial motion, we recorded the activity of five hip/thigh muscles with electromyography (EMG), thigh/pelvis/trunk position with accelerometers, and centre of pressure with a force plate. Linear regressions estimated the relationship between displacement of fascial layers and hip/trunk angles. Independent t-tests or Fisher's exact tests compared EMG and movement-related parameters between participants who demonstrated motion of the fascia in the proximal and distal directions. Thickness of the ITB and the loose connective tissue between its layers were calculated. Proximal displacement was observed in six (-4.1 ± 1.9 mm [superficial]) and two (-6.2 ± 2.0 mm [deep]) participants. Distal displacement was observed for seven participants for each layer (3.1 ± 1.1 mm [superficial]; 3.6 ± 1.3 mm [deep]). Four participants did not show displacement of the deep layer. Trunk lateral flexion and gluteus medius muscle activity were determinants of proximal motion of the superficial layer. Loose connective tissue was thinner in participants without displacement of the deep layer. Displacement of the ITB fascial layers varies between individuals. Variation related to differences in joint movements and muscle activity. This study highlights the complex interaction between fascia and movement.

The Iliotibial Band: A Complex Structure with Versatile Functions

The development of a pronounced iliotibial band (ITB) is an anatomically distinct evolution of humans. The mechanical behaviour of this “new” structure is still poorly understood and hotly debated in current literature. Iliotibial band syndrome (ITBS) is one of the leading causes of lateral knee pain injuries in runners. We currently lack a comprehensive understanding of the healthy behaviour of the ITB, and this is necessary prior to further investigating the aetiology of pathologies like ITBS. Therefore, the purpose of this narrative review was to collate the anatomical, biomechanical and clinical literature to understand how the mechanical function of the ITB is influenced by anatomical variation, posture and muscle activation. The complexity of understanding the mechanical function of the ITB is due, in part, to the presence of its two in-series muscles: gluteus maximus (GMAX) and tensor fascia latae (TFL). At present, we lack a fundamental understanding of how GMAX and TFL transmit force through the ITB and what mechanical role the ITB plays for movements like walking or running. While there is a range of proposed ITBS treatment strategies, robust evidence for effective treatments is still lacking. Interventions that directly target the running biomechanics suspected to increase either ITB strain or compression of lateral knee structures may have promise, but clinical randomised controlled trials are still required.

Conservative treatment of iliotibial band syndrome in runners: Are we targeting the right goals?

OBJECTIVE

Iliotibial band syndrome (ITBS) is presumably caused by excessive tension in the iliotibial band (ITB) leading to compression and inflammation of tissues lying beneath it. Usually managed conservatively, there is a lack of scientific evidence supporting the treatment recommendations, and high symptom recurrence rates cast doubt on their causal effectiveness. This review discusses the influence of common physiotherapeutic measures on risk factors contributing to tissue compression beneath the ITB.

METHODS

The potential pathogenic factors are presented on the basis of a simple biomechanical model showing the forces acting on the lateral aspect of the knee. Existent literature on the most commonly prescribed physiotherapeutic interventions is critically discussed against the background of this model. Practical recommendations for the optimization of physiotherapy are derived.

RESULTS

According to biomechanical considerations, ITBS may be promoted by anatomical predisposition, joint malalignments, aberrant activation of inserting muscles as well as excessive ITB stiffness. Hip abductor strengthening may correct excessive hip adduction but also increase ITB strain. Intermittent stretching interventions are unlikely to change the ITB's length or mechanical properties. Running retraining is a promising yet understudied intervention.

CONCLUSIONS

High-quality research directly testing different physiotherapeutic treatment approaches in randomized controlled trials is needed.

Restoring range of motion in reduced acetabular version by increasing femoral antetorsion - What about joint load?

BACKGROUND

Acetabular retroversion results in reduced range of motion, and is thought to contribute to femoroacetabular impingement. Severe retroversion can be corrected with a periacetabular osteotomy, which is a technically demanding intervention. In this study, we investigated whether increasing femoral antetorsion is a potential alternative to restore the range of motion and how this approach would affect hip joint loading.

METHODS

Six different finite element models of the same subject were built from MRI and used to simulate different load scenarios during stance phase, including healthy and pathological configurations with different acetabular version and femoral torsion angles. The subject's gait was analysed in our gait lab and motion data as well as joint reaction forces were integrated into the model. Hip range of motion, hip abductor muscle forces as well as localization and magnitude of hip joint loads were determined.

FINDINGS

The negative effects of acetabular retroversion on hip range of motion including flexion and internal rotation can be reversed by increasing femoral anteversion. The rotation of the femur furthermore affected muscular functionality by shortening the moment arms of the hip abductor muscles, resulting in increased abductor muscle forces, joint reaction forces and hip joint loading.

INTERPRETATION

Even though increased femoral antetorsion can compensate for the loss of hip range of motion due to reduced acetabular version, rotational ostotomy of the proximal femur is likely to alter muscular moment arms and therefore increase hip joint load, conflicting the goal of a long-term healthy joint.

Exploration of shear wave elastography measures of the iliotibial band during different tasks in pain-free runners

OBJECTIVES

To determine whether shear wave velocity (SWV) of the iliotibial band (ITB): i) increases with active and passive static tasks, and a dynamic task, ii) differs between ITB regions, iii) changes after exposure to running. Additionally, it aimed to determine the between-day reliability.

DESIGN

Case series & test-retest.

SETTING

Human movement unit laboratory.

PARTICIPANTS

Fifteen runners.

MAIN OUTCOME MEASURES

SWV was measured unilaterally in three regions of the ITB (proximal, middle and distal), during six tasks: rest and contraction (pre- and post-running), modified Ober test, standing, pelvic drop, and weight shift.

RESULTS

Compared to rest, SWV was higher during contraction and Ober test in the distal and middle regions, and higher for the middle region in standing and pelvic drop. No differences were found between regions. A tendency of decreased SWV was observed after running. Compared to the start of the dynamic task, SWV was greater at the end of the movement. Reliability was moderate-to-good for the middle region in the standing tasks (ICCs = 0.68 to 0.84).

CONCLUSION

SVW of the ITB was higher under passive or active tension. Comparisons between tasks/regions need to be considered in light of the small sample size and poor repeatability of some regions/conditions.

Phylogenetics of the Fascial System

The fascial system, due to its enormous capacity to connect all other body systems, is currently highlighted for a better understanding of human life and health. The evolutionary theory is the most accepted explanation today to describe the development of this enormous variety of life on our planet. The report presents phylogenesis through the eyes of the fascial system. The development of the fascial system and its adaptations have made it possible to increase Homo sapiens' survival and success. We present a historical contextualization of the evolutionary theory followed by the main changes in the movement fasciae, in the transverse diaphragms, visceral fasciae, dermis, subcutaneous tissue, and neural fasciae. The article presents the evolutionary perspective with the resulting increase in efficiency with less energy expenditure.

Proximal iliotibial band thickness as a cause for recalcitrant greater trochanteric pain syndrome

To investigate iliotibial band (ITB) diameter thickness at the greater trochanter in patients requiring iliotibial band release who have failed conservative modalities, in comparison to an asymptomatic patient population. A total of 68 subjects were selected to be reviewed using T2 axial plane MRI. The ITB diameter thickness was measured in 34 subjects who underwent surgical ITB release, and compared with a match-paired asymptomatic hip cohort consisting of 34 subjects. ITB diameter thickness was measured at the thickest location for each subject twice by two different examiners. Inter/intra class correlation coefficient was determined for ITB measurement technique accuracy, and the presence of recalcitrant proximal hip pain was evaluated. Interclass correlation coefficient with 95% confidence was measured to be 0.953. The average thickness for ITB surgical release subjects was measured to be 5.61 ± 2.10 mm, and for asymptomatic subjects 3.77 ± 0.79 mm (P < 0.001). The results of this study demonstrate a statistically significant positive relationship of an increased diameter thickness in the ITB in symptomatic patients who failed conservative therapy and underwent surgical intervention for treatment.

Why are Antagonist Muscles Co-activated in My Simulation? A Musculoskeletal Model for Analysing Human Locomotor Tasks

Existing "off-the-shelf" musculoskeletal models are problematic when simulating movements that involve substantial hip and knee flexion, such as the upstroke of pedalling, because they tend to generate excessive passive fibre force. The goal of this study was to develop a refined musculoskeletal model capable of simulating pedalling and fast running, in addition to walking, which predicts the activation patterns of muscles better than existing models. Specifically, we tested whether the anomalous co-activation of antagonist muscles, commonly observed in simulations, could be resolved if the passive forces generated by the underlying model were diminished. We refined the OpenSim™ model published by Rajagopal et al. (IEEE Trans Biomed Eng 63:1-1, 2016) by increasing the model's range of knee flexion, updating the paths of the knee muscles, and modifying the force-generating properties of eleven muscles. Simulations of pedalling, running and walking based on this model reproduced measured EMG activity better than simulations based on the existing model-even when both models tracked the same subject-specific kinematics. Improvements in the predicted activations were associated with decreases in the net passive moments; for example, the net passive knee moment during the upstroke of pedalling decreased from 36.9 N m (existing model) to 6.3 N m (refined model), resulting in a dramatic decrease in the co-activation of knee flexors. The refined model is available from SimTK.org and is suitable for analysing movements with up to 120° of hip flexion and 140° of knee flexion.

The human iliotibial band is specialized for elastic energy storage compared with the chimp fascia lata

This study examines whether the human iliotibial band (ITB) is specialized for elastic energy storage relative to the chimpanzee fascia lata (FL). To quantify the energy storage potential of these structures, we created computer models of human and chimpanzee lower limbs based on detailed anatomical dissections. We characterized the geometry and force-length properties of the FL, tensor fascia lata (TFL) and gluteus maximus (GMax) in four chimpanzee cadavers based on measurements of muscle architecture and moment arms about the hip and knee. We used the chimp model to estimate the forces and corresponding strains in the chimp FL during bipedal walking, and compared these data with analogous estimates from a model of the human ITB, accounting for differences in body mass and lower extremity posture. We estimate that the human ITB stores 15- to 20-times more elastic energy per unit body mass and stride than the chimp FL during bipedal walking. Because chimps walk with persistent hip flexion, the TFL and portions of GMax that insert on the FL undergo smaller excursions (origin to insertion) than muscles that insert on the human ITB. Also, because a smaller fraction of GMax inserts on the chimp FL than on the human ITB, and thus its mass-normalized physiological cross-sectional area is about three times less in chimps, the chimp FL probably transmits smaller muscle forces. These data provide new evidence that the human ITB is anatomically derived compared with the chimp FL and potentially contributes to locomotor economy during bipedal locomotion.