Medicine and Health Sciences Commons^™

Randomized Controlled Trial Of The Behavioral Intervention For Increasing Physical Activity In Multiple Sclerosis Project: Secondary, Patient-Reported Outcomes, Robert W. Motl, Brian M. Sandroff, Lara A. Pilutti, Gary R. Cutter, Roberto Aldunate, Ariel Kidwell, Rachel E. Bollaert

Exercise Science Faculty Research and Publications

Background

We undertook a randomized controlled trial (RCT) that investigated the effectiveness of a theory-based, Internet-delivered, behavioral intervention focusing on physical activity promotion for immediate and sustained improvements in secondary, patient-reported outcomes (PROs) of function, symptoms, and quality of life (QOL) in multiple sclerosis (MS).

Method

Persons with MS (N = 318) were recruited from throughout the United States and randomized into behavioral intervention (n = 159) or attention/social contact control (n = 159) conditions. The conditions were administered over a 6-month period by persons who were uninvolved in screening, recruitment, random assignment, and outcome assessment. There …

Who Was Wearing A Mask In 2021? Update On Gender-, Age-, And Location-Related Differences During The Covid-19 Pandemic, Michael H. Haischer, Rachel Beilfuss, Meggie Rose Hart, Lauren Opielinski, Emma Schmit, David Wrucke, Helena Zhao, Toni D. Uhrich, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Previous observational work from 2020 demonstrated gender-, age-, and location-related differences in mask-wearing behavior, despite the efficacy and public health messaging that emphasized face coverings in combatting the spread of COVID-19. In 2021, COVID-19 vaccinations and a corresponding change in public health policy became new considerations in deciding personal protective behaviors. To provide an update on mask wearers and resistors approximately one year after our initial study, we observed shoppers (n = 6,118) entering retail stores using the same experimental methodology. Approximately 26% of individuals wore a mask. Mask wearing has decreased across demographic groups compared to 2020. Aligning …

Moderate-To-Vigorous Physical Activity Is Related With Retinal Neuronal And Axonal Integrity In Persons With Multiple Sclerosis, Jeongwoon Kim, Rachel E. Bollaert, Jonathan Cerna, Brynn C. Adamson, Connor M. Robbs, Naiman A. Khan, Robert W. Motl

Exercise Science Faculty Research and Publications

Background

Moderate-to-vigorous physical activity (MVPA) may confer benefits for axonal and/or neuronal integrity in adults with multiple sclerosis (MS).

Purpose

Examine the association between device-measured MVPA with optical coherence tomography (OCT) metrics of retinal nerve fiber layer (RNFL) thickness and total macular volume (TMV) in persons with and without MS.

Methods

Adults with MS (N = 41), along with sex-matched healthy control (HC) participants (N = 79), underwent measurements of retinal morphology via OCT and wore an accelerometer for a period of 7 days as a measure of MVPA.

Results

Persons with MS had significantly lower MVPA, RNFL thickness, and …

Muscle-Specific Contributions To Lower Extremity Net Joint Moments While Squatting With Different External Loads, Kristof Kipp, Hoon Kim, William I. Wolf

Exercise Science Faculty Research and Publications

The purpose of this study was to determine muscle-specific contributions to lower extremity net joint moments (NJMs) during squats with different external loads. Nine healthy subjects performed sets of the back squat exercise with 0, 25, 50, and 75% of body mass as an added external load. Motion capture and force plate data were used to calculate NJMs and to estimate individual muscle forces via static optimization. Individual muscle forces were multiplied by their respective moment arms to calculate the resulting muscle-specific joint moment. Statistical parametric mapping (α = 0.05) was used to determine load-dependent changes in the time series …

Maximal Strength In Relation To Force And Velocity Patterns During Countermovement Jumps, Michael H. Haischer, John Krzyszkowski, Stuart Roche, Kristof Kipp

Exercise Science Faculty Research and Publications

Maximal strength is important for the performance of dynamic athletic activities, such as countermovement jumps (CMJ). Although measures of maximal strength appear related to discrete CMJ variables, such as peak ground reaction forces (GRF) and center-of-mass (COM) velocity, knowledge about the association between strength and the time series patterns during CMJ will help characterize changes that can be expected in dynamic movement with changes in maximal strength. Purpose: To investigate the associations between maximal strength and GRF and COM velocity patterns during CMJ. Methods: Nineteen female college lacrosse players performed 3 maximal-effort CMJs and isometric midthigh pull. GRF …

Hip And Knee Joint Angle Patterns And Kicking Velocity In Female And Male Professional Soccer Players: A Principal Component Analysis Of Waveforms Approach, Archit Navandar, Kristof Kipp, Enrique Navarro

Exercise Science Faculty Research and Publications

This study used principal component analysis (PCA) of waveforms to extract movement patterns from hip and knee angle time-series data; and determined if the extracted movement patterns were predictors of ball velocity during a soccer kick. Twenty-three female and nineteen male professional soccer players performed maximal effort instep kicks while motion capture and post-impact ball velocities data were recorded. Three-dimensional hip and knee joint angle time-series data were calculated from the beginning of the kicking leg’s backswing phase until the end of the follow-through phase and entered into separate PCAs for females and males. Three principal components (PC) (i.e., movement …

Accuracy Of Body Mass Index In Categorizing Weight Status In Children With Intellectual And Developmental Disabilities, Michele Polfuss, Bethany Forseth, Dale A. Schoeller, Chiang-Ching Huang, Andrea Moosreiner, Paula E. Papanek, Kathleen J. Sawin, Kimberley Zvara, Linda Bandini

Exercise Science Faculty Research and Publications

PURPOSE:

To identify the accuracy of Body Mass Index (BMI) to categorize body weight in a sample of children with spina bifida and Down syndrome as compared to typically developing peers.

METHODS:

A secondary analysis of 32 children with spina bifida, Down syndrome or no chronic illness. A calculated BMI was plotted on the Centers for Disease Control and Prevention age- and sex-specific BMI growth charts to determine each child’s weight status. Percentage of body fat, obtained by labeled water, was plotted on two different body fat percentile reference curves, one derived from a whole body measure (DXA) of body …

Influence Of The Bar Position On Joint-Level Biomechanics During Isometric Pulling Exercises, Nayun Ahn, Hoon Kim, John Krzyszkowski, Stuart Roche, Kristof Kipp

Exercise Science Faculty Research and Publications

The purpose of this study was to investigate the influence of the bar position on ankle, knee, and hip net joint moments (NJMs), relative muscular effort (RME), and vertical ground reaction forces (GRFs) during isometric pulling exercises, such as the isometric midthigh pull. Eight female lacrosse athletes performed maximal effort isometric pulls at 3 different bar positions (low: above patella, mid: midthigh, and high: crease of hip) while motion capture and GRF data were recorded. Net joint moments were calculated with inverse dynamics. Relative muscle effort was defined as the ratio between the inverse dynamics NJMs and the maximum theoretical …

Prediction Of Throwing Distance In The Men’S And Women’S Javelin Final At The 2017 Iaaf World Championships, John Krzyszkowski, Kristof Kipp

Exercise Science Faculty Research and Publications

The purpose of this study was to use regularised regression models to identify the most important biomechanical predictors of throwing distance in elite male (M) and female (F) javelin throwers at the 2017 IAAF world championships. Biomechanical data from 13 male and 12 female javelin throwers who competed at the 2017 IAAF world championships were obtained from an official scientific IAAF report. Regularised regression models were used to investigate the associations between throwing distance and release parameters, whole-body kinematic and joint-level kinematic data. The regularised regression models identified two biomechanical predictors of throwing distances in both M and F javelin …

Hip Moment And Knee Power Eccentric Utilisation Ratios Determine Lower-Extremity Stretch-Shortening Cycle Performance, Kristof Kipp, John Krzyszkowski, Jordi Heeneman

Exercise Science Faculty Research and Publications

The eccentric utilisation ratio (EUR) is calculated as the ratio between countermovement jump (CMJ) and squat jump (SJ) heights, and is an indicator of lower-extremity stretch-shortening cycle (SSC) performance in athletes. Joint-based EUR can also be calculated but have never been reported. The purpose of this study was to investigate whether jump height-based (JH-based) EUR can be predicted by joint-specific EUR. Nine NCAA Division I college athletes (age: 21 ± 1 year, height: 1.75 ± 0.15 m, mass: 71 ± 20 kg) performed three SJ and CMJ. During all jumps, kinematic and kinetic data were obtained and used to calculate …

Phase-Iii, Randomized Controlled Trial Of The Behavioral Intervention For Increasing Physical Activity In Multiple Sclerosis: Project Bipams, Robert W. Motl, Brian M. Sandroff, Brooks C. Wingo, Justin Mccroskey, Lara A. Pilutti, Gary R. Cutter, Rachel Bollaert, Edward Mcauley

Exercise Science Faculty Research and Publications

Background

We propose a phase-III, randomized controlled trial (RCT) that examines the effectiveness of a behavioral intervention based on social cognitive theory (SCT) and delivered through the Internet using e-learning approaches for increasing physical activity and secondary outcomes (e.g., symptoms) in a large sample of people with multiple sclerosis (MS) residing throughout the United States.

Methods/design

The proposed phase-III trial will use a parallel group, RCT design that examines the effect of a 6-month behavioral intervention for increasing physical activity and secondarily improving mobility, cognition, symptoms, and quality of life (QOL) in persons with MS. The primary outcome is accelerometer-measured …

Total Energy Expenditure And Body Composition Of Children With Developmental Disabilities, Michele L. Polfuss, Kathleen J. Sawin, Paula E. Papanek, Linda Bandini, Bethany Forseth, Andrea Moosreiner, Kimberley Zvara, Dale A. Schoeller

Exercise Science Faculty Research and Publications

Background

Obesity prevalence is increased in children with developmental disabilities, specifically in children with spina bifida and Down syndrome. Energy expenditure, a critical aspect of weight management, has been extensively studied in the typically developing population, but not adequately studied in children with developmental disabilities.

Objective

Determine energy expenditure, fat-free mass and body fat percentile and the impact of these findings on recommended caloric intake in children with spina bifida and Down syndrome.

Methods/Measures

This pilot study included 36 children, 18 with spina bifida, 9 with Down syndrome and 9 typically developing children. Half of the children with spina bifida …

Sex Differences In Mechanisms Of Recovery After Isometric And Dynamic Fatiguing Tasks, Jonathon Senefeld, Hugo M. Pereira, Nicholas Elliott, Tejin Yoon, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Purpose The purpose of this study was to determine whether supraspinal mechanisms contribute to the sex difference in fatigability during and recovery from a dynamic and isometric fatiguing task with the knee extensors.

Methods: Transcranial magnetic stimulation and electrical stimulation were used to determine voluntary activation and contractile properties of the knee extensors in 14 men and 17 women (20.8 ± 1.9 yr) after a 1) 60-s sustained, maximal voluntary isometric contraction (MVIC), and 2) dynamic fatiguing task involving 120 maximal voluntary concentric contractions with a 20% MVIC load.

Results: There were no differences between men and women in the …

Sex Differences In Neuromuscular Fatigability Of The Knee Extensors Post-Stroke, Meghan Kirking, Reivian B. Barillas, Philip A. Nelson, Sandra K. Hunter, Allison Hyngstrom

Exercise Science Faculty Research and Publications

Background and Purpose: Despite the implications of optimizing strength training post-stroke, little is known about the differences in fatigability between men and women with chronic stroke. The purpose of this study was to determine the sex differences in knee extensor muscle fatigability and potential mechanisms in individuals with stroke. Methods: Eighteen participants (10 men, eight women) with chronic stroke (≥6 months) and 23 (12 men, 11 women) nonstroke controls participated in the study. Participants performed an intermittent isometric contraction task (6 s contraction, 3 s rest) at 30% of maximal voluntary contraction (MVC) torque until failure to maintain the target …

A Biomechanical Comparison Of Successful And Unsuccessful Power Clean Attempts, Kristof Kipp, Carolyn M. Meinerz

Exercise Science Faculty Research and Publications

Although the power clean is an almost ubiquitous exercise in the strength and conditioning setting, relatively little is known about the biomechanics of successful and unsuccessful power clean lift attempts. The purpose of this study was to determine biomechanical differences between successful and unsuccessful power clean lift attempts in male collegiate athletes. Fifteen male lacrosse players (Age: 20.1 ± 1.2; Height: 1.78 ± 0.07 m; Body mass: 80.4 ± 8.1 kg; Relative one-repetition maximum power clean: 1.25 ± 0.13 kg/kg) were videotaped during a lifting session that required the completion of maximal effort power cleans to establish a one-repetition maximum. …

Muscle Function And Fatigability Of Trunk Flexors In Males And Females, Rita Deering, Jonathon Senefeld, Tatyana Pashibin, Donald A. Neumann, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Background

Optimal function of the abdominal muscles is necessary for several life functions including lifting and carrying tasks. Sex differences in strength and fatigability are established for many limb muscles and back extensor muscles, but it is unknown if sex differences exist for the abdominal muscles despite their functional importance.

Methods

Eighteen females (24.3 ± 4.8 years) and 15 males (24.1 ± 6.6 years) performed (1) isometric trunk flexion maximal voluntary contractions (MVCs) in a range of trunk positions to establish a torque-angle curve and (2) submaximal (50% MVC), intermittent isometric contraction (6 s on, 4 s off) until task …

Wellness And Multiple Sclerosis: The National Ms Society Establishes A Wellness Research Working Group And Research Priorities, Robert W. Motl, Ellen M. Mowry, Dawn M. Ehde, Nicholas G. Larocca, Kathy E. Smith, Kathleen Costello, Lynne Shinto, Alex V. Ng, Amy B. Sullivan, Barbara Geisser, Kevin K. Mccully, Bo Fernhall, Malachy Bishop, Matthew Plow, Patrizia Casaccia, Nancy D. Chiaravalloti

Exercise Science Faculty Research and Publications

Background:

People with multiple sclerosis (MS) have identified “wellness” and associated behaviors as a high priority based on “social media listening” undertaken by the National MS Society (i.e. the Society).

Objective:

The Society recently convened a group that consisted of researchers with experience in MS and wellness-related research, Society staff members, and an individual with MS for developing recommendations regarding a wellness research agenda.

Method:

The members of the group engaged in focal reviews and discussions involving the state of science within three approaches for promoting wellness in MS, namely diet, exercise, and emotional wellness.

Results:

That process informed a …

The Relevance Of Sex Differences In Performance Fatigability, Sandra K. Hunter

Exercise Science Faculty Research and Publications

Performance fatigability differs between men and women for a range of fatiguing tasks. Women are usually less fatigable than men, and this is most widely described for isometric fatiguing contractions and some dynamic tasks. The sex difference in fatigability is specific to the task demands so that one mechanism is not universal, including any sex differences in skeletal muscle physiology, muscle perfusion, and voluntary activation. However, there are substantial knowledge gaps about the task dependency of the sex differences in fatigability, the involved mechanisms, and the relevance to clinical populations and with advanced age. The knowledge gaps are in part …

Muscle-Specific Effective Mechanical Advantage And Joint Impulse In Weightlifting, Kristof Kipp, Chad Harris

Exercise Science Faculty Research and Publications

Lifting greater loads during weightlifting exercises may theoretically be achieved through increasing the magnitudes of net joint impulses or manipulating the joints’ effective mechanical advantage (EMA). The purpose of this study was to investigate muscle-specific EMA and joint impulse as well as impulse-momentum characteristics of the lifter-barbell system across a range of external loads during the execution of the clean. Collegiate-level weightlifters performed submaximal cleans at 65, 75, and 85% of their 1-repetition maximum (1-RM) while data from a motion analysis system and a force plate were used to calculate lifter-barbell system impulse and velocity, as well as net extensor …

Mechanical Demands Of The Hang Power Clean And Jump Shrug: A Joint-Level Perspective, Kristof Kipp, Philip Malloy, Jordan Smith, Matthew D. Giordanelli, Michael T. Kiely, Christopher Geiser, Timothy J. Suchomel

Exercise Science Faculty Research and Publications

The purpose of this study was to investigate the joint- and load-dependent changes in the mechanical demands of the lower extremity joints during the hang power clean (HPC) and the jump shrug (JS). Fifteen male lacrosse players were recruited from an NCAA DI team, and completed three sets of the HPC and JS at 30%, 50%, and 70% of their HPC 1-Repetition Maximum (1-RM HPC) in a counterbalanced and randomized order. Motion analysis and force plate technology were used to calculate the positive work, propulsive phase duration, and peak concentric power at the hip, knee, and ankle joints. Separate three-way …

Reliability And Validity Of Ratings Of Perceived Exertion In Persons With Multiple Sclerosis, Brice T. Cleland, Benjamin A. Ingraham, Molly C. Pitluck, Alexander V. Ng

Exercise Science Faculty Research and Publications

Objective: To test the reliability and validity of using the Borg rating of perceived exertion (RPE) scale (ratings 6e20) in persons with multiple sclerosis (PwMS).

Design: Nonrandomized repeated measures.

Setting: Research laboratory.

Participants: Volunteer sample (N=27) comprised of 16 PwMS (10 women) and 11 age-matched persons without multiple sclerosis (MS) (6 women). Clinical measures included symptomatic fatigue, depression, and MS functional capacity.

Interventions: A submaximal cycling test was performed to estimate maximal capacity. Participants then pedaled for 2 minutes at 50% and 60% of predicted maximal oxygen consumption per unit time (V̇O₂), and physiological measures and RPE were …

Can A Home-Based Cardiac Physical Activity Program Improve The Physical Function Quality Of Life In Children With Fontan Circulation?, Roni M. Jacobsen, Salil Ginde, Kathleen Mussatto, Jennifer Neubauer, Michael G. Earing, Michael E. Danduran

Exercise Science Faculty Research and Publications

Objective

Patients after Fontan operation for complex congenital heart disease (CHD) have decreased exercise capacity and report reduced health-related quality of life (HRQOL). Studies suggest hospital-based cardiac physical activity programs can improve HRQOL and exercise capacity in patients with CHD; however, these programs have variable adherence rates. The impact of a home-based cardiac physical activity program in Fontan survivors is unclear. This pilot study evaluated the safety, feasibility, and benefits of an innovative home-based physical activity program on HRQOL in Fontan patients.

Methods

A total of 14 children, 8–12 years, with Fontan circulation enrolled in a 12-week moderate/high intensity home-based …

Survivors Speak: A Qualitative Analysis Of Motivational Factors Influencing Breast Cancer Survivors’ Participation In A Sprint Distance Triathlon, Karen Marie Robinson, Linda B. Piacentine, Leslie J. Waltke, Alexander V. Ng, Judy A. Tjoe

Exercise Science Faculty Research and Publications

Aims and Objectives

To examine motivational factors influencing breast cancer survivors to participate in triathlon training, complete a triathlon and maintain an exercise thereafter.

Background

Routine exercise has been shown to improve quality of life and reduce recurrence for breast cancer survivors. Yet physical and psychological factors present barriers for initiating and maintaining an exercise routine. Research is limited in exploring factors of exercise motivation from the survivor's perspective.

Design

Qualitative design using focus groups and individual follow-up phone interviews to explore motivation for exercise initiation and maintenance.

Methods

One to two weeks after completing a triathlon, 11 breast cancer …

Hip External Rotator Strength Is Associated With Better Dynamic Control Of The Lower Extremity During Landing Tasks, Philip Malloy, Alexander Morgan, Carolyn M. Meinerz, Christopher Geiser, Kristof Kipp

Exercise Science Faculty Research and Publications

Hip external rotator strength is associated with better dynamic control of the lower extremity during landing tasks. J Strength Cond Res 30(1): 282–291, 2016—The purpose of this study was to determine the association between hip strength and lower extremity kinematics and kinetics during unanticipated single-leg landing and cutting tasks in collegiate female soccer players. Twenty-three National Collegiate Athletic Association division I female soccer players were recruited for strength testing and biomechanical analysis. Maximal isometric hip abduction and external rotation strength were measured using a hand-held dynamometer and expressed as muscle torque (force × femoral length) and normalized to body weight. …

Body Composition Measurement In Children With Cerebral Palsy, Spina Bifida And Spinal Cord Injury: A Systematic Review Of The Literature, Michele L. Polfuss, Paula E. Papanek, Fallon Meyer-Wentland, Andrea Moosreiner, Lenore R. Wilkas, Kathleen J. Sawin

Exercise Science Faculty Research and Publications

Pediatric obesity is a major health concern that has an increased prevalence in children with special needs. In order to categorize a child’s weight, an assessment of body composition is needed. Obtaining an accurate body composition measurement in children with special needs has many challenges associated with it. This perplexing scenario limits the provider’s ability to screen, prevent and treat an abnormal weight status in this vulnerable population. This systematic review summarizes common methods of body composition measurements, their strengths and limitations and reviews the literature when measurements were used in children with cerebral palsy, spina bifida and spinal cord …

Impaired Hyperemic Response To Exercise Post Stroke, Matthew J. Durand, Spencer A. Murphy, Kathleen K. Schaefer, Sandra K. Hunter, Brian D. Schmit, David D. Gutterman, Allison Hyngstrom

Exercise Science Faculty Research and Publications

Individuals with chronic stroke have reduced perfusion of the paretic lower limb at rest; however, the hyperemic response to graded muscle contractions in this patient population has not been examined. This study quantified blood flow to the paretic and non-paretic lower limbs of subjects with chronic stroke after submaximal contractions of the knee extensor muscles and correlated those measures with limb function and activity. Ten subjects with chronic stroke and ten controls had blood flow through the superficial femoral artery quantified with ultrasonography before and immediately after 10 second contractions of the knee extensor muscles at 20, 40, 60, and …

The Association Of Dorsiflexion Flexibility On Knee Kinematics And Kinetics During A Drop Vertical Jump In Healthy Female Athletes, Philip Malloy, Alexander Morgan, Carolyn M. Meinerz, Christopher Geiser, Kristof Kipp

Exercise Science Faculty Research and Publications

Purpose

While previous studies have examined the association between ankle dorsiflexion flexibility and deleterious landing postures, it is not currently known how landing kinetics are influenced by ankle dorsiflexion flexibility. The purpose of this study was to examine whether ankle dorsiflexion flexibility was associated with landing kinematics and kinetics that have been shown to increase the risk of anterior cruciate ligament (ACL) injury in female athletes.

Methods

Twenty-three female collegiate soccer players participated in a preseason screening that included the assessment of ankle dorsiflexion flexibility and lower-body kinematics and kinetics during a drop vertical jump task.

Results

The results demonstrated …

Anticipatory Effects On Lower Extremity Neuromechanics During A Cutting Task, Carolyn M. Meinerz, Philip Malloy, Christopher Geiser, Kristof Kipp

Exercise Science Faculty Research and Publications

Context: Continued research into the mechanism of noncontact anterior cruciate ligament injury helps to improve clinical interventions and injury-prevention strategies. A better understanding of the effects of anticipation on landing neuromechanics may benefit training interventions.

Objective: To determine the effects of anticipation on lower extremity neuromechanics during a single-legged land-and-cut task.

Design: Controlled laboratory study.

Setting: University biomechanics laboratory.

Participants: Eighteen female National Collegiate Athletic Association Division I collegiate soccer players (age = 19.7 ± 0.8 years, height = 167.3 ± 6.0 cm, mass = 66.1 ± 2.1 kg).

Intervention(s): Participants performed a single-legged land-and-cut task under anticipated and unanticipated …

Using Group Model Building To Understand Factors That Influence Childhood Obesity In An Urban Environment, David A. Nelson, Christopher J. Simenz, Sarah P. O'Connor, Yvonne Greer, Ann L. Bachrach, Tony Shields, Brett A. Fuller, Katie Horrigan, Kathleen Pritchard, Judy B. Springer, John R. Meurer

Exercise Science Faculty Research and Publications

Background: Despite increased attention, conventional views of obesity are based upon individual behaviors, and children and parents living with obesity are assumed to be the primary problem solvers. Instead of focusing exclusively on individual reduction behaviors for childhood obesity, greater focus should be placed on better understanding existing community systems and their effects on obesity. The Milwaukee Childhood Obesity Prevention Project is a community-based coalition established to develop policy and environmental change strategies to impact childhood obesity in Milwaukee, Wisconsin. The coalition conducted a Group Model Building exercise to better understand root causes of childhood obesity in its community.

Methods: …

The Two-Hour Marathon: What's The Equivalent For Women?, Sandra K. Hunter, Michael J. Joyner, Andrew M. Jones

Exercise Science Faculty Research and Publications

The principal characteristic of the runner who may break the two-hour barrier in the marathon will be their sex: the person will be male. The fastest men outperform the fastest women because of sex differences in physiology including a higher VȮ2 max. This viewpoint addresses the questions of what is the two-hour equivalent for women, and who will break this barrier? The current sex difference in the world record for the marathon is ~10% which is slightly less than the mean sex difference in performance usually documented between elite men and women distance runners. Based on comparisons of the top …