Irene S Davis

Harvard Medical School | HMS · Department of Physical Medicine and Rehabilitation

Recent reports have suggested that there may be a relationship between footstrike pattern and overuse injury incidence and type. With the recent increase in wearable sensors, it is important to identify paradigms where the footstrike pattern can be detected in real-time from minimal data. Machine learning was used to classify tibial acceleration da...

Background Bone stress injury (BSI) is a common overuse injury in active women. BSIs can be classified as high-risk (pelvis, sacrum, and femoral neck) or low-risk (tibia, fibula, and metatarsals). Risk factors for BSI include low energy availability, menstrual dysfunction, and poor bone health. Higher vertical load rates during running have been ob...

Multisegmented foot models (MSFMs) capture kinematic and kinetic data of specific regions of the foot instead of representing the foot as a single, rigid segment. Models differ by the number of segments and segment definitions, so there is no consensus for best practice. It is unknown whether MSFMs yield the same joint kinematic and kinetic data an...

Lower extremity injuries are prevalent in military trainees, especially in female and older trainees. Modifiable factors that lead to higher injury risk in these subgroups are not clear. The purpose of this study was to identify whether external loading variables during military‐relevant tasks differ by age and sex in U.S. Army trainees. Data was c...

Background Patellofemoral pain (PFP) is among the most common injuries in runners. While multiple risk factors for patellofemoral pain have been investigated, the interactions of variables contributing to this condition have not been explored. This study aimed to classify runners with patellofemoral pain using a combination of factors including bio...

Recent reports have suggested that high loading rates during running, typically associated with a rearfoot strike pattern, may be related to overuse injuries. With the recent increase in wearable sensors, it is important to identify paradigms where the footstrike pattern can be detected in real-time from minimal data. Machine learning was used to i...

The purpose of this study was to develop a machine learning model to reconstruct time series kinematic and kinetic profiles of the ankle and knee joint across six different tasks using an ankle-mounted IMU. Four male collegiate basketball players performed repeated tasks, including walking, jogging, running, sidestep cutting, max-height jumping, an...

INTRODUCTION Monitoring ankle and knee joint moments in the field is important for assessing the risk of sports injury and monitoring rehabilitation. Inertial Measurement Units (IMUs) provide a low-cost and accessible opportunity to assess movement outside the laboratory, but it remains to be seen whether IMUs can predict joint moments across a wid...

Peak tibial accelerations (TAs) during running are strongly related to early stance vertical ground reaction forces (GRFs), which are associated with musculoskeletal injury. However, few studies have examined these correlations during walking, and none have evaluated them during walking with loads, a relevant activity for military personnel. Our pu...

Recent studies have suggested that 95% of modern runners land with a rearfoot strike (RFS) pattern. However, we hypothesize that running with an RFS pattern is indicative of an evolutionary mismatch that can lead to musculoskeletal injury. This perspective is predicated on the notion that our ancestors evolved to run barefoot and primarily with a f...

Background Runners with a rearfoot strike pattern typically show high vertical ground reaction force loading rates (LRs), that are associated with injuries, compared with forefoot strikers. However, some runners with a rearfoot strike pattern run in a way that reduces LRs. Our purpose was to identify differences in running mechanics between rearfoo...

Several open-source platforms for markerless motion capture offer the ability to track 2-dimensional (2D) kinematics using simple digital video cameras. We sought to establish the performance of one of these platforms, DeepLabCut. Eighty-four runners who had sagittal plane videos recorded of their left lower leg were included in the study. Data fro...

Purpose : Bone stress injuries (BSIs) are common in female runners, and recurrent BSI rates are high. Previous work suggests an association between higher impact loading during running and tibial BSI. However, it is unknown whether impact loading and fatigue related loading changes discriminate women with a history of multiple BSIs. This study comp...

Background The presence of bone marrow edema (BME) on magnetic resonance imaging (MRI) has been used to evaluate for bone stress injuries in athletes. Purpose To examine the prevalence of MRI findings, including BME, in a single male collegiate basketball team before and after a single season and to assess its association with clinically symptomat...

Patellofemoral pain is a common and often debilitating musculoskeletal condition. Clinical translation and evidence synthesis of patellofemoral pain research are compromised by heterogenous and often inadequately reported study details. This consensus statement and associated checklist provides standards for REPORTing of quantitative PatelloFemoral...

Minimal footwear has existed for tens of thousands of years and was originally designed to protect the sole of the foot. Over the past 50 years, most footwear has become increasingly more cushioned and supportive. Here we review evidence that minimal shoes are a better match to our feet which may result in a lower risk of musculoskeletal injury.

Background Acute hamstring injuries during sprinting have been attributed, in part, to the ground reaction forces experienced during early stance. However, no studies have investigated the factors associated with overuse hamstring injuries in endurance runners. Our purpose was to compare early stance ground reaction forces and step length between r...

Exertion may alter running mechanics and increase injury risk. Effects of exertion following gait-retraining are unknown. Objectives: To determine how exertion effects load rates, footstrike, and cadence in runners following a transition to forefoot strike (FFS) or increased cadence (CAD) gait-retraining. Methods: 33 (9 M, 24 F) healthy rearfoo...

Peak vertical tibial accelerations during running have shown strong correlations with vertical ground reaction force loading rates and some associations with injury. However, little attention has been given to tibial accelerations along the medial-lateral and anterior-posterior axes. Therefore, our purpose was to examine the correlation between pea...

Higher medial–lateral forces have been reported in individuals with stiffer foot arches. However, this was in a small sample of military personnel who ran with a rearfoot strike pattern. Therefore, our purpose was to investigate whether runners, both rearfoot and forefoot strikers, show different associations between medial–lateral forces and arch...

Peak tibial accelerations during running are of interest because of their correlation with vertical ground reaction force load rates and association with running injury. Previous work has demonstrated systematically lower accelerations measured with a bone- compared to skin-mounted accelerometer. However, no studies have assessed the effects of mor...

Metatarsal bone stress injuries (BSI) are common in athletic populations. BSIs are overuse injuries that result from an accumulation of microdamage that exceeds bone remodeling. Risk for metatarsal BSI is multifactorial and includes factors related to anatomy, biology and biomechanics. In this paper, anatomical factors including foot type, metatars...

There is little information on the reliability of inertial measurement units for capturing impact load metrics during sport-specific movements. The purpose of this study is to determine the reliability of the Blue Trident IMU sensors in measuring impact load, step count and cumulative bone stimulus during a series of soccer-related tasks. Ten healt...

Background: Inconsistent associations have been reported for impact-related ground reaction force variables and running injuries when grouping all injuries together. However, previous work has shown more consistent associations when focusing on specific injuries. Purpose: To compare ground reaction force variables between healthy and injured run...

Objective This study aims to 1) determine the feasibility of conducting a full-scale randomized controlled trial (RCT) evaluating the efficacy of a gait retraining program on decreasing knee pain and impact loading in people with knee osteoarthritis, and 2) provide an estimate of treatment effects for a gait retraining program compared to a traditi...

The COVID-19 pandemic transformed healthcare delivery, including rapid expansion of telehealth. Telerehabilitation, defined as therapy provided by physical therapy, occupational therapy and speech and language pathology, was rapidly adopted with goals to provide access to care and limit contagion. The purpose of this brief report was to describe fe...

Purpose: Despite the health benefits of running, the prevalence of running injuries (RRI) remains high. The underlying risk factors between these injuries are still not well understood. Therefore, the aim of this study was to compare biomechanical, anthropometric and demographic injury risk factors between different locations in injured recreationa...

Purpose of review: Movement retraining in rehabilitation is the process by which a motor program is changed with the overall goal of reducing pain or injury risk. Movement retraining is an important component of interventions to address patellofemoral pain. The purpose of this paper is to review the methods and results of current retraining studie...

The degree to which standard laboratory gait assessments accurately reflect impact loading in an outdoor running environment is currently unknown. Purpose: To compare tibial shock between treadmill and road marathon conditions. Methods: 192 runners (Men/Women: 105/87, Age: 44.9±10.8 yrs) completed a treadmill gait assessment while wearing a tib...

Objective: To examine the effect of a multifactorial, online injury prevention programme on the number of running-related injuries (RRIs) in recreational runners. Methods: Adult recreational runners who registered for a running event (distances 5 km up to 42.195 km) were randomised into the intervention group or control group. Participants in th...

Background: The loadrate of the vertical ground reaction force at impact has been associated with a variety of running injuries. Peak tibial shocks occur during the early stance phase and has been shown to be correlated to the loadrates in healthy runners using a rearfoot strike pattern. As a result, tibial accelerometry has been used as a surroga...

Youth running is defined as participation below age 18. Jumping/multidirectional loading sports (soccer, basketball) may optimize bone health. Psychological development requires monitoring to reduce risk of injuries and burnout. Adequate energy availability is essential for health; screening for disordered eating and optimizing nutrition is importa...

While running-related overuse injuries are multifactorial, many common injuries have been associated with high impact loading. High-impact loading, characterized by a high vertical loading rate, is influenced by the manner with which the foot strikes the ground. While most runners strike the ground with the heel first (RFS), evidence suggests that...

Background Excessive vertical impacts at landing are associated with common running injuries. Two primary gait-retraining interventions aimed at reducing impact forces are transition to forefoot strike (FFS) and increasing cadence (CAD). The objective of this study was to compare the short- and long-term effects of 2 gait-retraining interventions a...

Not all forefoot striking is equal Alessandra Matias1,2, Jereme Outerleys1, Isabel Sacco2, Irene Davis, FACSM1 1Spaulding National Running Center, Harvard Medical School, Cambridge, MA; 2Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR Rearfoot strike (RFS) runners typically exhibit an impact peak in their vertical ground...

Most people acquire motor skills through feedbackbased training. How the human brain processes sensory feedbacks during training, especially in a gait training, remain largely unclear. The purpose of this study is to explore how humans adopt a new gait pattern to reduce impacts during walking - with the aid of visual and audio feedbacks. This work...

Background: Increasing cadence is often recommended to reduce load rate and to lower injury risk. However, habitual cadence was recently shown to be unrelated to load rate. Cadence is likely influenced by leg length. If so, then cadence may be related to load rate when it is normalized to leg length. Objectives: To examine the relationship betwe...

Real time biofeedback gait retraining has been reported to be an effective intervention to lower the impact loading during gait. While many of the previous gait retraining studies have utilized a laboratory‐based setup, some studies used accelerometers affixed at the distal tibia to allow training outside the laboratory environment. However, many c...

Running is a popular sport for children in the United States. However, review of available literature on health effects and safety recommendations for youth running has not been previously conducted. Unique factors for injury include periods of growth during puberty and potential for growth plate injury. Youth runners may benefit from activities th...

Increased vertical impact loading during running has been associated with a variety of running related injuries including stress fractures, patellofemoral pain and plantar fasciitis. Purpose: The purpose of this study was to examine the acute and long-term effect of a gait retraining program aimed at teaching runners with high impact loading to r...

Category Other Introduction/Purpose While the etiology of injuries is multifactorial, impact loading, as measured by the loadrate of the vertical ground reaction force has been implicated. These loadrates are typically measured with a force plate. However, this limits the measure of impacts to laboratory environments. Tibial acceleration, another...

Category Sports Introduction/Purpose It is well established that elevated vertical loadrates on footstrike are a risk factor for developing running injuries. Overstriding, or increased foot and tibial angles at footstrike, has been theorized to increase loading rate. Thus, it is often suggested that runners shorten their stride to reduce their inj...

Patellofemoral pain affects a large proportion of the population, from adolescents to older adults, and carries a substantial personal and societal burden. An international group of scientists and clinicians meets biennially at the International Patellofemoral Research Retreat to share research findings related to patellofemoral pain conditions and...

Purpose: To examine the relationships between habitual running cadence and vertical loadrates in healthy and injured runners using habitual footstrike patterns. As CAD increased, we expected vertical loadrates would decrease. Methods: Healthy runners (n=32, 25 male) and injured runners (n=93, 45 male) seeking treatment were analyzed. Footstrike...

When optical motion capture is used for motion analysis, reflective markers or a digitizer are typically used to record the location of anatomical landmarks identified through palpation. The landmarks are then used to construct anatomical coordinate systems. Failure to consistently identify landmarks through palpation over repeat tests creates arti...

Barefoot and minimal footwear running has led to greater interest in the biomechanical effects of different types of footwear. The effect of running footwear on dynamic stability is not well understood. The purpose of this study was to compare dynamic stability and impact loading across 3 footwear conditions; barefoot, minimal footwear and standard...

It is believed that human ancestors evolved the ability to run bipedally approximately 2 million years ago. This form of locomotion may have been important to our survival and likely has influenced the evolution of our body form. As our bodies have adapted to run, it seems unusual that up to 79% of modern day runners are injured annually. The etiol...

Introduction: Running with a forefoot strike (FFS) pattern has been suggested to reduce the risk of overuse running injuries, due to a reduced vertical loadrate compared with rearfoot strike (RFS) running. However, resultant loadrate has been reported to be similar between foot strikes when running in traditional shoes, leading to questions regard...

Symmetry of loading during gait has been improved in individuals with amputations and joint replacements using an instrumented treadmill. However, this equipment is not readily available in clinics or at home where training typically occurs. Development of a cheaper, mobile system would allow for clinical adoption of these gait retraining technique...

Background: Minimalist shoes have gained popularity recently because it is speculated to strengthen the foot muscles and foot arches, which may help to resist injuries. However, previous studies provided limited evidence supporting the link between changes in muscle size and footwear transition. Therefore, this study sought to examine the effects...