Irene S. Davis

Bio: Irene S. Davis is an academic researcher from Harvard University. The author has contributed to research in topics: Patellofemoral pain syndrome & Stress fractures. The author has an hindex of 63, co-authored 182 publications receiving 12544 citations. Previous affiliations of Irene S. Davis include Spaulding Rehabilitation Hospital & American Physical Therapy Association.

Foot strike patterns and collision forces in habitually barefoot versus shod runners

Abstract: Humans have engaged in endurance running for millions of years, but the modern running shoe was not invented until the 1970s. For most of human evolutionary history, runners were either barefoot or wore minimal footwear such as sandals or moccasins with smaller heels and little cushioning relative to modern running shoes. We wondered how runners coped with the impact caused by the foot colliding with the ground before the invention of the modern shoe. Here we show that habitually barefoot endurance runners often land on the fore-foot (fore-foot strike) before bringing down the heel, but they sometimes land with a flat foot (mid-foot strike) or, less often, on the heel (rear-foot strike). In contrast, habitually shod runners mostly rear-foot strike, facilitated by the elevated and cushioned heel of the modern running shoe. Kinematic and kinetic analyses show that even on hard surfaces, barefoot runners who fore-foot strike generate smaller collision forces than shod rear-foot strikers. This difference results primarily from a more plantarflexed foot at landing and more ankle compliance during impact, decreasing the effective mass of the body that collides with the ground. Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.

Biomechanical factors associated with tibial stress fracture in female runners.

Abstract: MILNER, C. E., R. FERBER, C. D. POLLARD, J. HAMILL, and I. S. DAVIS. Biomechanical Factors Associated with Tibial Stress Fracture in Female Runners. Med. Sci. Sports Exerc., Vol. 38, No. 2, pp. 323–328, 2006. Purpose: Tibial stress fractures (TSF) are among the most serious running injuries, typically requiring 6–8 wk for recovery. This cross-sectional study was conducted to determine whether differences in structure and running mechanics exist between trained distance runners with a history of prior TSF and those who have never sustained a fracture. Methods: Female runners with a rearfoot strike pattern, aged between 18 and 45 yr and running at least 32 kmIwk j1 , were recruited for this study. Participants in the study were 20 subjects with a history of TSF and 20 ageand mileage-matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected during overground running at 3.7 mIs j1 using a six-camera motion capture system, force platform, and accelerometer. Variables of interest were vertical impact peak, instantaneous and average vertical loading rates, instantaneous and average loading rates during braking, knee flexion excursion, ankle and knee stiffness, and peak tibial shock. Tibial varum was measured in standing. Tibial area moment of inertia was calculated from tibial x-ray studies for a subset of runners. Results: The TSF group had significantly greater instantaneous and average vertical loading rates and tibial shock than the control group. The magnitude of tibial shock predicted group membership successfully in 70% of cases. Conclusion: These data indicate that a history of TSF in runners is associated with

Proximal and Distal Influences on Hip and Knee Kinematics in Runners With Patellofemoral Pain During a Prolonged Run

Abstract: Study Design Cross-sectional experimental laboratory study. Objectives To investigate the relationships between hip strength and hip kinematics, and between arch structure and knee kinematics during prolonged treadmill running in runners with and without patellofemoral pain syndrome (PFPS). Background Hip weakness can lead to excessive femoral motions that adversely affect patellofemoral joint mechanics. Similarly, foot mechanics, which are influenced by foot structure, are also known to influence patellofemoral joint mechanics. Thus, proximal and distal factors should be considered when studying individuals with PFPS. Methods and Measures Twenty recreational runners with PFPS (5 male, 15 female) and 20 matched uninjured runners participated in the study. Hip abduction and hip external rotation isometric strength measurements were collected before and after a prolonged run, while the arch height index was recorded on all runners before the run. Lower extremity kinematic data were collected at the beginnin...

Foot strike patterns and collision forces in habitually barefoot versus shod runners

Abstract: Humans have engaged in endurance running for millions of years, but the modern running shoe was not invented until the 1970s. For most of human evolutionary history, runners were either barefoot or wore minimal footwear such as sandals or moccasins with smaller heels and little cushioning relative to modern running shoes. We wondered how runners coped with the impact caused by the foot colliding with the ground before the invention of the modern shoe. Here we show that habitually barefoot endurance runners often land on the fore-foot (fore-foot strike) before bringing down the heel, but they sometimes land with a flat foot (mid-foot strike) or, less often, on the heel (rear-foot strike). In contrast, habitually shod runners mostly rear-foot strike, facilitated by the elevated and cushioned heel of the modern running shoe. Kinematic and kinetic analyses show that even on hard surfaces, barefoot runners who fore-foot strike generate smaller collision forces than shod rear-foot strikers. This difference results primarily from a more plantarflexed foot at landing and more ankle compliance during impact, decreasing the effective mass of the body that collides with the ground. Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.

Biomechanical Measures During Landing and Postural Stability Predict Second Anterior Cruciate Ligament Injury After Anterior Cruciate Ligament Reconstruction and Return to Sport

Abstract: BackgroundAthletes who return to sport participation after anterior cruciate ligament reconstruction (ACLR) have a higher risk of a second anterior cruciate ligament injury (either reinjury or contralateral injury) compared with non—anterior cruciate ligament— injured athletes.HypothesesProspective measures of neuromuscular control and postural stability after ACLR will predict relative increased risk for a second anterior cruciate ligament injury.Study DesignCohort study (prognosis); Level of evidence, 2.MethodsFifty-six athletes underwent a prospective biomechanical screening after ACLR using 3-dimensional motion analysis during a drop vertical jump maneuver and postural stability assessment before return to pivoting and cutting sports. After the initial test session, each subject was followed for 12 months for occurrence of a second anterior cruciate ligament injury. Lower extremity joint kinematics, kinetics, and postural stability were assessed and analyzed. Analysis of variance and logistic regressi...

Augmented visual, auditory, haptic, and multimodal feedback in motor learning: A review

Abstract: It is generally accepted that augmented feedback, provided by a human expert or a technical display, effectively enhances motor learning. However, discussion of the way to most effectively provide augmented feedback has been controversial. Related studies have focused primarily on simple or artificial tasks enhanced by visual feedback. Recently, technical advances have made it possible also to investigate more complex, realistic motor tasks and to implement not only visual, but also auditory, haptic, or multimodal augmented feedback. The aim of this review is to address the potential of augmented unimodal and multimodal feedback in the framework of motor learning theories. The review addresses the reasons for the different impacts of feedback strategies within or between the visual, auditory, and haptic modalities and the challenges that need to be overcome to provide appropriate feedback in these modalities, either in isolation or in combination. Accordingly, the design criteria for successful visual, auditory, haptic, and multimodal feedback are elaborated.

The Influence of Abnormal Hip Mechanics on Knee Injury: A Biomechanical Perspective

Abstract: Synopsis During the last decade, there has been a growing body of literature suggesting that proximal factors may play a contributory role with respect to knee injuries. A review of the biomechanical and clinical studies in this area indicates that impaired muscular control of the hip, pelvis, and trunk can affect tibiofemoral and patellofemoral joint kinematics and kinetics in multiple planes. In particular, there is evidence that motion impairments at the hip may underlie injuries such as anterior cruciate ligament tears, iliotibial band syndrome, and patellofemoral joint pain. In addition, the literature suggests that females may be more disposed to proximal influences than males. Based on the evidence presented as part of this clinical commentary, it can be argued that interventions which address proximal impairments may be beneficial for patients who present with various knee conditions. More specifically, a biomechanical argument can be made for the incorporation of pelvis and trunk stability, as we...

How much is too much? (Part 2) International Olympic Committee consensus statement on load in sport and risk of illness

Abstract: Athletes participating in elite sports are exposed to high training loads and increasingly saturated competition calendars. Emerging evidence indicates that poor load management is a major risk factor for injury. The International Olympic Committee convened an expert group to review the scientific evidence for the relationship of load (defined broadly to include rapid changes in training and competition load, competition calendar congestion, psychological load and travel) and health outcomes in sport. We summarise the results linking load to risk of injury in athletes, and provide athletes, coaches and support staff with practical guidelines to manage load in sport. This consensus statement includes guidelines for (1) prescription of training and competition load, as well as for (2) monitoring of training, competition and psychological load, athlete well-being and injury. In the process, we identified research priorities.