Effect of Strength and Plyometric Training on Kinematics in Female Novice Runners.

ABSTRACT: Harrison, K, Williams, DSB III, Darter, BJ, Zernicke, RF, Shall, M, and Finucane, S. Effect of strength and plyometric training on kinematics in female novice runners. J Strength Cond Res 38(6): 1048-1055, 2024-Both running performance and injury have been associated with running kinematics. Plyometric training improves run performance and reduces injury risk in court-sport and field-sport athletes. The aim of this study was to assess longitudinal changes in kinematics in novice runners before and after a typical beginners' running program, compared with those who perform a plyometric intervention before running. Fifty-seven novice female runners were assigned to the control group (8 weeks walking +8 weeks running) or the intervention group (8 weeks strength or plyometric training +8 weeks running). Kinematics were assessed at baseline, 8 weeks, and 16 weeks. Joint angles throughout the stride of those who completed the training ( n = 21) were compared between groups and assessment time points using a statistical parametric mapping 2-way analysis of variance, with group and study time point as independent variables. There was no interaction effect of group and study time point ( p > 0.05), indicating that both training programs had similar effects on running kinematics. There was a main effect of time for sagittal plane knee and hip kinematics ( p < 0.001); after training, subjects ran with a more extended leg, particularly during swing. Programs of 8 weeks of preparatory training, followed by 8 weeks of running, resulted in altered sagittal plane biomechanics, which have previously been related to improved running economy. A greater volume of plyometric, run training or concurrent plyometric and run training may be required to elicit changes in running form associated with lower injury risk.

Assessing spring-mass similarity in elite and recreational runners.

The dynamic complexity and individualization of running biomechanics has challenged the development of objective and comparative gait measures. Here, we present and explore several novel biomechanical metrics for running that are informed by a canonical inter-species gait template-the spring-mass model. The measures assess running mechanics systemically against the template via quantifying characteristics of a runner's kinetics relative to the energy-conserving elastic system-i.e., their "spring-mass similarity". Applying these metrics in a retrospective cohort investigation, we studied the overground kinetics of two heterogenous populations of runners in two footwear conditions: elite and recreational athletes in shod and barefoot conditions. Across all measures and within foot strike types, the elite runners exhibited mechanics that were more similar to those of the ideally elastic spring-mass template. The elite runners had more symmetric bounces, less discrepancy (i.e., greater coordination) between horizontal and vertical kinetic changes, and better fit to a spring-mass vertical ground reaction force time series. Barefoot running elicited greater kinetic coordination in the recreational runners. At a faster speed, the elites further improved their similarity to the template. Overall, the more economical elite group exhibited greater likeness to the linearly elastic, energy-conserving spring-mass system than their recreational counterparts. This study introduces novel biomechanical measures related to performance in distance running. More broadly, it provides new, approachable metrics for systemic quantification of gait biomechanics in runners across all demographics. These metrics may be applied to assess a runner's global biomechanical response to a variety of interventions, including training adaptations, rehabilitation programs, and footwear conditions.

Lower Extremity Inverse Kinematics Results Differ Between Inertial Measurement Unit- and Marker-Derived Gait Data.

In-lab, marker-based gait analyses may not represent real-world gait. Real-world gait analyses may be feasible using inertial measurement units (IMUs) in combination with open-source data processing pipelines (OpenSense). Before using OpenSense to study real-world gait, we must determine whether these methods estimate joint kinematics similarly to traditional marker-based motion capture (MoCap) and differentiate groups with clinically different gait mechanics. Healthy young and older adults and older adults with knee osteoarthritis completed this study. We captured MoCap and IMU data during overground walking at 2 speeds. MoCap and IMU kinematics were computed with OpenSim workflows. We tested whether sagittal kinematics differed between MoCap and IMU, whether tools detected between-group differences similarly, and whether kinematics differed between tools by speed. MoCap showed more anterior pelvic tilt (0%-100% stride) and joint flexion than IMU (hip: 0%-38% and 61%-100% stride; knee: 0%-38%, 58%-89%, and 95%-99% stride; and ankle: 6%-99% stride). There were no significant tool-by-group interactions. We found significant tool-by-speed interactions for all angles. While MoCap- and IMU-derived kinematics differed, the lack of tool-by-group interactions suggests consistent tracking across clinical cohorts. Results of the current study suggest that IMU-derived kinematics with OpenSense may enable reliable evaluation of gait in real-world settings.

Aligning Organizational Priorities and System Policies to Support Implementation Scale-Up of a Tailored Classroom-Based Physical Activity Intervention in Low-Resource Schools.

BACKGROUND: A mismatch between organizational priorities and system-level policies can negatively impact implementation and sustainment of classroom-based physical activity (PA) interventions. The purpose of this study was twofold: (1) present methods to systematically identify organization- and system-level implementation barriers, and (2) align organizational priorities and system policies by designing multi-level implementation strategies. This alignment will support implementation scale-up of a tailored PA intervention in one low-resource intermediate school district (ISD; 16 districts, 32 schools) in central Michigan. METHODS: Multi-level assessments of organizational readiness were conducted using the Hexagon Discussion and Analysis Tool to assess intervention-context fit, the Wellness School Assessment Tool 3.0 to evaluate district PA policy strength and comprehensiveness, and semi-structured interviews were conducted to assess administrative support and priorities related to PA programming. RESULTS: Our assessments revealed three implementation barriers: limited structural capacity to sustain teacher training, limited resources across districts and school buildings to support teachers, and misalignment of ISD and district PA policies and priorities. CONCLUSIONS: Greater attention to organizational capacity and existing infrastructure should be considered a priori to support effective implementation and sustainment of PA interventions in low-resource schools.

A Novel Policy Alignment and Enhancement Process to Improve Sustainment of School-Based Physical Activity Programming.

The purpose of the current study was twofold: (1) to evaluate the strength and comprehensiveness of district wellness policies in one central Michigan intermediate school district (ISD; 16 districts), and (2) to pilot a novel policy alignment and enhancement process in one district within the ISD to improve sustainment of district-wide physical activity (PA) programming. Policy evaluation and alignment were determined using WellSAT 3.0. The Exploration, Preparation, Implementation, Sustainment (EPIS) framework was used to guide a seven-step policy alignment and enhancement process. Initial evaluation of the PA policy for the ISD revealed a strength score of 19/100 (i.e., included weak and non-specific language) and 31/100 for comprehensiveness (i.e., mentioned few components of the Comprehensive School Physical Activity Program). For the pilot school district, initial strength scores were 19/100 and 38/100 for comprehensiveness (exploration). An alignment of the tailored PA policy with current practices resulted in a 100% increase in strength (score of 38/100), and 132% increase in comprehensiveness (score of 88/100; preparation). However, district administrators encountered barriers to adopting the tailored policy and subsequently integrated the PA requirements into their curriculum guide and school improvement plan (implementation and sustainment). Future research should examine the effectiveness of our EPIS-informed policy evaluation, alignment, and enhancement process to promote widespread increases in student PA.

Identifying latent classes of Relative Energy Deficiency in Sport (RED-S) consequences in a sample of collegiate female cross country runners.

OBJECTIVE: The purpose of this study was to identify patterns of clustering of the 10 health consequences identified in the Relative Energy Deficiency in Sport (RED-S) framework among collegiate female Cross-Country runners. We also assessed risk characteristics associated with each cluster. METHODS: This randomly sampled population included 211 current National Collegiate Athletics Association (NCAA) Division I (DI) female cross country runners who completed a quantitative survey. We used latent class analysis (LCA) to group athletes into mutually exclusive classes based on shared response patterns of RED-S consequences. We computed descriptive statistics to identify demographics, personal characteristics, disordered eating and emotional health characteristics associated with each class. RESULTS: The average age of the sample was 21 years with mean body mass index 20.4 kg/m2. The LCA identified three unique classes of potential RED-S presentations: (1) low probability of RED-S consequences; (2) complex physical and psychological concerns with a higher burden of cardiovascular concern and (3) very high probability of anxiety with high burden of menstrual disturbance, bone injury and gastrointestinal concern. All classes were characterised by high levels of menstrual disturbance and distinguished by the number and burden of other potential RED-S consequences and in reported abuse history, emotional regulation and perfectionism. CONCLUSION: This study identified a high burden of menstrual disturbance in NCAA D1 cross country runners, and three unique presentations of RED-S consequences. Future research is warranted to better understand how early prevention and intervention strategies may mitigate RED-S consequences in distance runners.

Rapid cycle adaptation of a classroom-based intervention to promote equity in access to youth physical activity.

Our objective was to systematically adapt Interrupting Prolonged sitting with ACTivity (InPACT), a classroom-based physical activity intervention, for home delivery to equitably increase access to structured youth physical activity opportunities during the COVID-19 pandemic. Key steps in the rapid-cycle research adaptation process included: (Step 1) identifying partner organizations; (Steps 2 and 3) engaging in problem and knowledge exploration to examine the problem from different perspectives; (Steps 4 and 5) initiating solution development and testing by selecting an intervention and adapting the format and content for home delivery. Using Rapid RE-AIM to guide online assessment and refinement of InPACT at Home; and (Step 6) utilizing dissemination strategies to extend the reach of the program. Core elements of the InPACT program that were retained included: the use of exercise videos, maintenance of the intervention dose, and teacher-led physical activities. Key adaptations included: utilization of physical education specialists to develop the exercise videos, incorporation of health messaging in videos, and utilization of dissemination strategies (intervention website) to reach K-12 students across the state. Intervention website reach included all 83 counties in Michigan, but goals were not met for website pageviews (5,147; 85% of goal) and video view duration (7 min 19 sec; 37% of goal). Accordingly, dissemination was expanded to include public television broadcasting (monthly viewers: 500,000) and videos were shortened to 8 minutes. Dissemination and implementation science frameworks guided the rapid adaptation of an existing intervention, InPACT, to equitably increase access to structured youth physical activity opportunities at home during the pandemic.

Homo sapiens May Incorporate Daily Acute Cycles of "Conditioning-Deconditioning" to Maintain Musculoskeletal Integrity: Need to Integrate with Biological Clocks and Circadian Rhythm Mediators.

Human evolution required adaptation to the boundary conditions of Earth, including 1 g gravity. The bipedal mobility of Homo sapiens in that gravitational field causes ground reaction force (GRF) loading of their lower extremities, influencing the integrity of the tissues of those extremities. However, humans usually experience such loading during the day and then a period of relative unloading at night. Many studies have indicated that loading of tissues and cells of the musculoskeletal (MSK) system can inhibit their responses to biological mediators such as cytokines and growth factors. Such findings raise the possibility that humans use such cycles of acute conditioning and deconditioning of the cells and tissues of the MSK system to elaborate critical mediators and responsiveness in parallel with these cycles, particularly involving GRF loading. However, humans also experience circadian rhythms with the levels of a number of mediators influenced by day/night cycles, as well as various levels of biological clocks. Thus, if responsiveness to MSK-generated mediators also occurs during the unloaded part of the daily cycle, that response must be integrated with circadian variations as well. Furthermore, it is also possible that responsiveness to circadian rhythm mediators may be regulated by MSK tissue loading. This review will examine evidence for the above scenario and postulate how interactions could be both regulated and studied, and how extension of the acute cycles biased towards deconditioning could lead to loss of tissue integrity.

Risk Factors for COVID-19 in College Students Identified by Physical, Mental, and Social Health Reported During the Fall 2020 Semester: Observational Study Using the Roadmap App and Fitbit Wearable Sensors.

BACKGROUND: The COVID-19 pandemic triggered a seismic shift in education to web-based learning. With nearly 20 million students enrolled in colleges across the United States, the long-simmering mental health crisis in college students was likely further exacerbated by the pandemic. OBJECTIVE: This study leveraged mobile health (mHealth) technology and sought to (1) characterize self-reported outcomes of physical, mental, and social health by COVID-19 status; (2) assess physical activity through consumer-grade wearable sensors (Fitbit); and (3) identify risk factors associated with COVID-19 positivity in a population of college students prior to release of the vaccine. METHODS: After completing a baseline assessment (ie, at Time 0 [T0]) of demographics, mental, and social health constructs through the Roadmap 2.0 app, participants were instructed to use the app freely, wear the Fitbit, and complete subsequent assessments at T1, T2, and T3, followed by a COVID-19 assessment of history and timing of COVID-19 testing and diagnosis (T4: ~14 days after T3). Continuous measures were described using mean (SD) values, while categorical measures were summarized as n (%) values. Formal comparisons were made on the basis of COVID-19 status. The multivariate model was determined by entering all statistically significant variables (P<.05) in univariable associations at once and then removing one variable at a time through backward selection until the optimal model was obtained. RESULTS: During the fall 2020 semester, 1997 participants consented, enrolled, and met criteria for data analyses. There was a high prevalence of anxiety, as assessed by the State Trait Anxiety Index, with moderate and severe levels in 465 (24%) and 970 (49%) students, respectively. Approximately one-third of students reported having a mental health disorder (n=656, 33%). The average daily steps recorded in this student population was approximately 6500 (mean 6474, SD 3371). Neither reported mental health nor step count were significant based on COVID-19 status (P=.52). Our analyses revealed significant associations of COVID-19 positivity with the use of marijuana and alcohol (P=.02 and P=.046, respectively) and with lower belief in public health measures (P=.003). In addition, graduate students were less likely and those with ≥20 roommates were more likely to report a COVID-19 diagnosis (P=.009). CONCLUSIONS: Mental health problems were common in this student population. Several factors, including substance use, were associated with the risk of COVID-19. These data highlight important areas for further attention, such as prioritizing innovative strategies that address health and well-being, considering the potential long-term effects of COVID-19 on college students. TRIAL REGISTRATION: ClinicalTrials.gov NCT04766788; https://clinicaltrials.gov/ct2/show/NCT04766788. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.2196/29561.

Position-Specific Physical Workload Intensities in American Collegiate Football Training.

ABSTRACT: MamonJr, MA, Olthof, SBH, Burns, GT, Lepley, AS, Kozloff, KM, and Zernicke, RF. Position-specific physical workload intensities in American collegiate football training. J Strength Cond Res 36(2): 420-426, 2022-Quantifying player training loads allows football coaching staff to make informed adjustments to the volume and intensity of training. Physical workload intensity in American football practices have not been extensively quantified. The current study examined physical workload intensities across positions in American collegiate football during training. Data from player tracking technology (Catapult Vector) were collected from 72 American football players (National Collegiate Athletic Association Division I) during in-season practices. Players were involved in individualized skill (indy), team playbook (team), and special team (ST) drills during practice and analyzed for their specialist offensive or defensive role (e.g., linebacker or wide receiver). Player running (i.e., high-speed running and sprint) and accelerations (i.e., high-intensity PlayerLoad and high-intensity inertial movement analysis) per minute were of interest. Drill type and practice day had significant effects on all workload intensity metrics (p < 0.01), but not position. Greater running intensities were seen in ST drills compared with other drill types. Tuesday practice sessions had greater overall intensities compared with other days. Interaction effect of position and drill type was significant (p < 0.001) for all intensity metrics, indicating that position groups exhibited unique workload responses to the drill types. Drill type and practice day interaction effect was significant for all intensity metrics (p < 0.01). The findings may be informative for coaches to tailor physical workloads of practice drills for positional roles in preparation for games and practices. Player tracking technology can add value for strength and conditioning coaches to adjust training programs based on position-specific on-field demands of players.

A simple computational method to estimate stance velocity in running.

Running dynamical analyses typically approximate a runner's stance velocity as the average stride cycle velocity (the average running speed). That approximation necessarily overestimates stance velocity and biases subsequent results. Stance velocity is crucial in kinetic spring-mass analyses of running, where approximation of a runner's impact angle and calculation of leg stiffness require that input. Here, a new method is presented to approximate a runner's stance velocity via measurement of contact and flight times with the runner's average speed, leg length or height, and mass. This method accurately estimated the stance velocity of simulated spring-mass systems across typical running speeds of 3.5-5.5 m s-1 (r>0.99) and more accurately estimated the impact angle and leg stiffness. The method also accurately estimated the peak horizontal ground reaction force across speeds (r=0.82), but the bias magnitude increased with speed. Robustness of the new method was further tested for runners at 2.5, 3.5 and 4.5 m s-1, and the new method provided steeper impact angles than those from traditional estimates and correspondingly higher leg stiffnesses, analogous to the observations in the simulation models. Horizontal ground reaction force estimates were weakly correlated in braking and propulsion. They were improved by a corrective algorithm, but the intra- and inter-individual variation persisted. The directionality and magnitude of angle and stiffness estimates in the human runners were similar to simulations, suggesting the new method more accurately modeled runners' spring-mass characteristics by using an accurate approximation of stance velocity. The new method can improve traditional kinetic analyses of running where stance velocity recordings are not captured with kinematic recordings and extend opportunities for accurate field-based analyses with limited measurement sources.

Adults with knee osteoarthritis use different coordinative strategies to transition from swing to stance compared to young asymptomatic adults.

BACKGROUND: Neuromuscular changes that occur with aging or joint pathology likely alter the coordinative strategies that adults use to walk and to recover from perturbations during gait. Differences in coordination patterns or in how coordination changes in response to a challenge may provide insight into neuromuscular targets for falls prevention interventions. RESEARCH QUESTION: Do young asymptomatic adults, older asymptomatic adults, and older adults with knee OA alter their lower extremity segment coordination differently in response to an increase in walking speed?. METHODS: We captured lower extremity kinematics using inertial measurement units as 29 participants (10 young, 10 older, 9 older with knee osteoarthritis) walked on a treadmill at self-selected preferred and faster speeds. We calculated lower extremity segment coordination and coordination variability using vector coding. We compared coordination and its variability among groups and speeds. RESULTS: There were no significant interactions between group and speed. Overall group or speed differences in coordination or variability occurred mostly during terminal swing or early stance. Coordination patterns differed between young adults and adults with knee osteoarthritis in all segment couples during terminal swing and at the foot vs. shank during early stance. During these same gait cycle phases for the foot vs. shank and shank vs. thigh segment couples, coordination patterns shifted towards those of young adults when participants walked faster. Where coordination variability differed by group or speed, it was lower in the young adults than in the older adults with or without knee osteoarthritis and at faster walking speed. SIGNIFICANCE: Our results identified that older adults with knee osteoarthritis have a different strategy for transitioning from swing to stance compared to young adults, especially at distal limb segments. These results may help target fall prevention interventions to specific gait cycle phases or strategies.

Bouncing behavior of sub-four minute milers.

Elite middle distance runners present as a unique population in which to explore biomechanical phenomena in relation to running speed, as their training and racing spans a broad spectrum of paces. However, there have been no comprehensive investigations of running mechanics across speeds within this population. Here, we used the spring-mass model of running to explore global mechanical behavior across speeds in these runners. Ten elite-level 1500 m and mile runners (mean 1500 m best: 3:37.3 ± 3.6 s; mile: 3:54.6 ± 3.9 s) and ten highly trained 1500 m and mile runners (mean 1500 m best: 4:07.6 ± 3.7 s; mile: 4:27.4 ± 4.1 s) ran on a treadmill at 10 speeds where temporal measures were recorded. Spatiotemporal and spring-mass characteristics and their corresponding variation were calculated within and across speeds. All spatiotemporal measures changed with speed in both groups, but the changes were less substantial in the elites. The elite runners ran with greater approximated vertical forces (+ 0.16 BW) and steeper impact angles (+ 3.1°) across speeds. Moreover, the elites ran with greater leg and vertical stiffnesses (+ 2.1 kN/m and + 3.6 kN/m) across speeds. Neither group changed leg stiffness with increasing speeds, but both groups increased vertical stiffness (1.6 kN/m per km/h), and the elite runners more so (further + 0.4 kN/m per km/h). The elite runners also demonstrated lower variability in their spatiotemporal behavior across speeds. Together, these findings suggested that elite middle distance runners may have distinct global mechanical patterns across running speeds, where they behave as stiffer, less variable spring-mass systems compared to highly trained, but sub-elite counterparts.

Comparison of Frontal and Transverse Plane Kinematics Related to Knee Injury in Novice Versus Experienced Female Runners.

Novice runners experience a higher incidence of knee injury than experienced runners, which may be related to aberrant frontal and transverse plane kinematics. However, differences in kinematics between novice and experienced runners have not been fully explored. For this study, 10 novice and 10 experienced female runners ran on a treadmill at 2.68 m/s. Ankle, knee, and hip joint angles during the stance phase were measured using a 3-dimensional motion capture system and modeled using cubic splines. Spline models were compared between groups using a generalized linear model (α = .05). Ninety-five percent confidence intervals of the difference between joint angles throughout stance were constructed to identify specific periods of stance where groups differed in joint position. Angle-angle diagrams of ankle and hip position in the frontal and transverse planes were constructed to depict joint coordination. Novice runners displayed less hip adduction, but greater knee abduction and knee internal rotation compared to experienced runners. Differences in knee joint position may be explained by coordination of hip and ankle motion. Greater knee abduction and knee internal rotation displayed by novice runners compared with experienced runners may help to explain their higher risk for injury.

Improving spring-mass parameter estimation in running using nonlinear regression methods.

Runners are commonly modeled as spring-mass systems, but the traditional calculations of these models rely on discrete observations during the gait cycle (e.g. maximal vertical force) and simplifying assumptions (e.g. leg length), challenging the predicative capacity and generalizability of observations. We present a method to model runners as spring-mass systems using nonlinear regression (NLR) and the full vertical ground reaction force (vGRF) time series without additional inputs and fewer traditional parameter assumptions. We derived and validated a time-dependent vGRF function characterized by four spring-mass parameters - stiffness, touchdown angle, leg length and contact time - using a sinusoidal approximation. Next, we compared the NLR-estimated spring-mass parameters with traditional calculations in runners. The mixed-effect NLR method (ME NLR) modeled the observed vGRF best (RMSE:155 N) compared with a conventional sinusoid approximation (RMSE: 230 N). Against the conventional methods, its estimations provided similar stiffness approximations (-0.2±0.6 kN m-1) with moderately steeper angles (1.2±0.7 deg), longer legs (+4.2±2.3 cm) and shorter effective contact times (-12±4 ms). Together, these vGRF-driven system parameters more closely approximated the observed vertical impulses (observed: 214.8 N s; ME NLR: 209.0 N s; traditional: 223.6 N s). Finally, we generated spring-mass simulations from traditional and ME NLR parameter estimates to assess the predicative capacity of each method to model stable running systems. In 6/7 subjects, ME NLR parameters generated models that ran with equal or greater stability than traditional estimates. ME NLR modeling of the vGRF in running is therefore a useful tool to assess runners holistically as spring-mass systems with fewer measurement sources or anthropometric assumptions. Furthermore, its utility as statistical framework lends itself to more complex mixed-effects modeling to explore research questions in running.

Biomechanical Loads and Their Effects on Player Performance in NCAA D-I Male Basketball Games.

Basketball games and training sessions are characterized by quick actions and many scoring attempts, which pose biomechanical loads on the bodies of the players. Inertial Measurement Units (IMUs) capture these biomechanical loads as PlayerLoad and Inertial Movement Analysis (IMA) and teams collect those data to monitor adaptations to training schedules. However, the association of biomechanical loads with game performance is a relatively unexplored area. The aims of the current study were to determine the statistical relations between biomechanical loads in games and training with game performance. Biomechanical training and game load measures and player-level and team-level game stats from one college basketball team of two seasons were included in the dataset. The training loads were obtained on the days before gameday. A three-step analysis pipeline modeled: (i) relations between team-level game stats and the win/loss probabilities of the team, (ii) associations between the player-level training and game loads and their game stats, and (iii) associations between player-level training loads and game loads. The results showed that offensive and defensive game stats increased the odds of winning, but several stats were subject to positional and individual performance variability. Further analyses, therefore, included total points [PTS], two-point field goals, and defensive rebounds (DEF REB) that were less subject to those influences. Increases in game loads were significantly associated with game stats. In addition, training loads significantly affected the game loads in the following game. In particular, increased loads 2 days before the game resulted in increased expected game loads. Those findings suggested that biomechanical loads were good predictors for game performance. Specifically, the game loads were good predictors for game stats, and training loads 2 days before gameday were good predictors for the expected game load. The current analyses accounted for the variation in loads of players and stats that enabled modeling the expected game performance for each individual. Coaches, trainers, and sports scientists can use these findings to further optimize training plans and possibly make in-game decisions for individual player performance.

Cultural and environmental associations with body image, diet and well-being in NCAA DI female distance runners: a qualitative analysis.

OBJECTIVE: We aimed to describe current and former National Collegiate Athletic Association (NCAA) Division One (DI) female distance runners' experiences of perceived norms of body image and disordered eating in their sport, as well as the emergence and influence of coach-athlete power dynamics.This manuscript reports a qualitative research study (consisting of interviews and thematic analysis) of women athletes' experiences of perceived norms of body image and disordered eating in their sport. We also report athletes' experiences of coach-athlete power dynamics. METHODS: The study sample included 29 current and former female NCAA DI female distance runners, defined as competing in 800-metre distance or greater. Interviews were conducted, audio-recorded and hand transcribed. A thematic analysis was performed and presented. RESULTS: Two major themes emerged: (1) sport body ideals and body image norms and myths that exist in the sport, and (2) the power dynamic between athletes and coaches. It is not clear whether sport body ideals and culture of running influences coaching culture, or whether the coaches-who maintain positions of power in the sport-perpetuate the culture. These themes likely feed into each other and reinforce the existing and dominant mentalities of the sport. CONCLUSION: Sport body image ideals and the power dynamic between coach and athlete may contribute to female athlete's risk of disordered eating and body image disturbance. We call for the NCAA and athletic departments to develop and implement prevention and intervention programmes to prevent eating and body image disorders in this high-risk population.

Propulsive joint powers track with sensor-derived angular velocity: A potential tool for lab-less gait retraining.

Lower propulsive joint powers, particularly at the ankle, are often observed in older compared to young adults. Interventions to increase joint powers often require labs with motion capture and force treadmill technology. Translating these interventions out of the lab requires identifying portable measures that track (i.e., strongly correlate with) changes in joint powers. The purpose of this study was to determine if kinematics collected using inertial measurement units (IMUs) correlate with propulsive joint powers calculated using inverse dynamics. We collected data simultaneously with motion capture, force plates, and IMU sensors as young and older adults walked at varying speeds overground in a laboratory. Hip, knee, and ankle joint powers were calculated using inverse dynamics and positive peaks in the second half of stance were identified as the propulsive powers of interest. Raw IMU gyroscope data were oriented to a functional medial-lateral axis and peaks in the second half of stance were identified for segment (thigh, shank, foot) and joint (hip, knee, ankle) angular velocities. Pearson correlation coefficients were calculated between peak joint powers and peak angular velocities. We identified significant (all p < 0.001) correlations between hip joint power and hip and thigh angular velocities (r = 0.80-0.83) and between ankle joint power and ankle, shank, and foot angular velocities (r = 0.77-0.89). Correlation strength was similar between young and older adults and between segment and joint angular velocities. These results suggest that changes in joint powers longitudinally or over the course of an intervention could be tracked using a minimal set of wearable sensors.

Optimal Human Functioning Requires Exercise Across the Lifespan: Mobility in a 1g Environment Is Intrinsic to the Integrity of Multiple Biological Systems.

It is widely acknowledged that achieving and maintaining a healthier lifestyle can be enhanced through regular participation in sport and physical activity. Coevally, a growing number of health professionals regard exercise as a legitimate intervention strategy for those who have lost their health. Exercise has been shown to be effective for overweight or obese individuals, who are at risk to lose their health due to development of type II diabetes, cardiovascular disease, as well as, infiltration of muscles, bone and other organs with fat, so it can be considered medicine. However, exercise and associated mobility likely also have a strong prevention component that can effectively contribute to the maintenance of the integrity of multiple biological systems for those who do not have overt risk factors or ongoing disease. While prevention is preferred over intervention in the context of disease, it is clear that exercise and associated mobility, generally, can be an effective influence, although overtraining and excessive loading can be deleterious to health. The basis for the generally positive influence of exercise likely lies in the fact that many of our physiological systems are designed to function in the mechanically dynamic and active 1g environment of Earth (e.g., muscles, cartilage, ligaments, tendons, bones, and cardiovascular system, and neuro-cognitive function), and nearly all these systems subscribe to the "use it or lose it" paradigm. This conclusion is supported by the changes observed over the more than 50 years of space flight and exposure to microgravity conditions. Therefore, the premise advanced is: "exercise is preventative for loss of health due to age-related decline in the integrity of several physiological systems via constant reinforcement of those systems, and thus, optimal levels of exercise and physical activity are endemic to, essential for, and intrinsic to optimal health and wellbeing."