Nationally Automated Colonoscopy Performance Feedback Increases Polyp Detection: the NED APRIQOT Randomised Controlled Trial.

BACKGROUND AND AIMS: Post-colonoscopy colorectal cancer incidence and mortality rates are higher for endoscopists with low polyp detection rates. Using the UK's National Endoscopy Database (NED), which automatically captures real-time data, we assessed if providing feedback of case-mix-adjusted Mean Number of Polyps (aMNP), as a key performance indicator, improved endoscopists' performance. Feedback was delivered via a theory-informed evidence-based audit and feedback intervention. METHODS: This multicentre, prospective, NED Automated Performance Reports to Improve Quality Outcomes Trial (NED-APRIQOT) randomised NHS endoscopy centres to intervention or control. Intervention-arm endoscopists were emailed tailored monthly reports automatically generated within NED, informed by qualitative interviews and behaviour change theory. The primary outcome was endoscopists' aMNP during the 9-month intervention. RESULTS: From November 2020-July 2021, 541 endoscopists across 36 centres (19 intervention; 17 control) performed 54,770 procedures during the intervention, and 15,960 procedures during the 3-months post-intervention period. Comparing intervention-arm to control-arm endoscopists during the intervention period: aMNP was non-significantly higher (7%, 95% confidence interval (CI) -1% to 14%; p=0·08). Unadjusted MNP (10%, 95%CI 1-20%) and polyp detection rate (PDR) (10%, 95%CI 4-16%) were significantly higher. Differences were not maintained in the post-intervention period. In the intervention-arm, endoscopists accessing NED-APRIQOT webpages had higher aMNP than those who did not (118 vs 102 aMNP, p=0.03). CONCLUSION: Although our automated feedback intervention did not increase aMNP significantly in the intervention period; MNP and PDR did significantly improve. Engaged endoscopists benefited most and improvements were not maintained post-intervention; future work should address engagement in feedback and consider the effectiveness of continuous feedback. www.isrctn.org ISRCTN11126923.

The role of constraints and information gaps in driving risky medicine purchasing practices in four African countries.

Substandard and falsified (SF) medical products pose a major threat to public health and socioeconomic development, particularly in low- and middle-income countries. In response, public education campaigns have been developed to alert consumers about the risks of SF medicines and provide guidance on 'safer' practices, along with other demand- and supply-side measures. However, little is currently known about the potential effectiveness of such campaigns while structural constraints to accessing quality-assured medicines persist. This paper analyses survey data on medicine purchasing practices, information and constraints from four African countries (Ghana, Nigeria, Sierra Leone and Uganda; n > 1000 per country). Using multivariate regression and structural equation modelling, we present what we believe to be the first attempt to tease apart, statistically, the effects of an information gap vs structural constraints in driving potential public exposure to SF medicines. The analysis confirms that less privileged groups (including, variously, those in rural settlements, with low levels of formal education, not in paid employment, often women and households with a disability or long-term sickness) are disproportionately potentially exposed to SF medicines; these same demographic groups also tend to have lower levels of awareness and experience greater levels of constraint. Despite the constraints, our models suggest that public health education may have an important role to play in modifying some (but not all) risky practices. Appropriately targeted public messaging can thus be a useful part of the toolbox in the fight against SF medicines, but it can only work effectively in combination with wider-reaching reforms to address higher-level vulnerabilities in pharmaceutical supply chains in Africa and expand access to quality-assured public-sector health services.

Can a Smartphone Application Help Address Barriers to Reporting Substandard/Falsified Medical Products? A Pilot Study in Tanzania and Indonesia.

INTRODUCTION: Reporting is an essential component of efforts to combat the distribution and circulation of substandard and falsified (SF) medical products worldwide. However, little is known about why health care professionals (HCPs) do not report suspect products to the national medicine regulatory authority (NMRA) and what measures might address this. This pilot study aimed to assess the utility of a smartphone application for reporting SF medical products in Tanzania and Indonesia. METHODS: At baseline, in 2017, HCPs completed a survey describing perceived barriers to reporting and received training in the identification of SF products and received use of the smartphone reporting application (N=309). The application reporting system was piloted for 6 months. Evaluations took place with HCPs and NMRA staff at the midpoint and endline of the pilot study (2018). RESULTS: At baseline, HCPs surveyed (n=254) identified the following key barriers to reporting: difficulties identifying SF products, frustrations with existing reporting systems, and fears that reporting may have personal or reputational repercussions. During the pilot period, HCPs submitted a total of 36 reports of 27 products to the NMRAs in their respective countries; of these, 8 products were determined to be SF and 2 were unregistered. In all 10 cases, appropriate regulatory action was taken. Feedback from HCPs and NMRA staff was positive in both countries, suggesting that the application addressed several barriers to reporting as it was convenient and, importantly, opened a line of communication between HCPs and the NMRA. However, the application did not address all barriers to reporting, such as concerns of repercussions. CONCLUSION: The findings suggest that this smartphone application may be useful for improving HCPs' reporting of suspected SF products. Developing and piloting similar reporting applications in other countries and contexts is required.

Minithoracotomy vs Conventional Sternotomy for Mitral Valve Repair: A Randomized Clinical Trial.

Importance: The safety and effectiveness of mitral valve repair via thoracoscopically-guided minithoracotomy (minithoracotomy) compared with median sternotomy (sternotomy) in patients with degenerative mitral valve regurgitation is uncertain. Objective: To compare the safety and effectiveness of minithoracotomy vs sternotomy mitral valve repair in a randomized trial. Design, Setting, and Participants: A pragmatic, multicenter, superiority, randomized clinical trial in 10 tertiary care institutions in the UK. Participants were adults with degenerative mitral regurgitation undergoing mitral valve repair surgery. Interventions: Participants were randomized 1:1 with concealed allocation to receive either minithoracotomy or sternotomy mitral valve repair performed by an expert surgeon. Main Outcomes and Measures: The primary outcome was physical functioning and associated return to usual activities measured by change from baseline in the 36-Item Short Form Health Survey (SF-36) version 2 physical functioning scale 12 weeks after the index surgery, assessed by an independent researcher masked to the intervention. Secondary outcomes included recurrent mitral regurgitation grade, physical activity, and quality of life. The prespecified safety outcomes included death, repeat mitral valve surgery, or heart failure hospitalization up to 1 year. Results: Between November 2016 and January 2021, 330 participants were randomized (mean age, 67 years, 100 female [30%]); 166 were allocated to minithoracotomy and 164 allocated to sternotomy, of whom 309 underwent surgery and 294 reported the primary outcome. At 12 weeks, the mean between-group difference in the change in the SF-36 physical function T score was 0.68 (95% CI, -1.89 to 3.26). Valve repair rates (≈ 96%) were similar in both groups. Echocardiography demonstrated mitral regurgitation severity as none or mild for 92% of participants at 1 year with no difference between groups. The composite safety outcome occurred in 5.4% (9 of 166) of patients undergoing minithoracotomy and 6.1% (10 of 163) undergoing sternotomy at 1 year. Conclusions and relevance: Minithoracotomy is not superior to sternotomy in recovery of physical function at 12 weeks. Minithoracotomy achieves high rates and quality of valve repair and has similar safety outcomes at 1 year to sternotomy. The results provide evidence to inform shared decision-making and treatment guidelines. Trial Registration: isrctn.org Identifier: ISRCTN13930454.

Prehabilitation in elective patients undergoing cardiac surgery: a randomised control trial (THE PrEPS TRIAL) - a study protocol.

INTRODUCTION: Prehabilitation prior to surgery has been shown to reduce postoperative complications, reduce length of hospital stay and improve quality of life after cancer and limb reconstruction surgery. However, there are minimal data on the impact of prehabilitation in patients undergoing cardiac surgery, despite the fact these patients are generally older and have more comorbidities and frailty. This trial will assess the feasibility and impact of a prehabilitation intervention consisting of exercise and inspiratory muscle training on preoperative functional exercise capacity in adult patients awaiting elective cardiac surgery, and determine any impact on clinical outcomes after surgery. METHODS AND ANALYSIS: PrEPS is a randomised controlled single-centre trial recruiting 180 participants undergoing elective cardiac surgery. Participants will be randomised in a 1:1 ratio to standard presurgical care or standard care plus a prehabilitation intervention. The primary outcome will be change in functional exercise capacity measured as change in the 6 min walk test distance from baseline. Secondary outcomes will evaluate the impact of prehabilitation on preoperative and postoperative outcomes including; respiratory function, health-related quality of life, anxiety and depression, frailty, and postoperative complications and resource use. This trial will evaluate if a prehabilitation intervention can improve preoperative physical function, inspiratory muscle function, frailty and quality of life prior to surgery in elective patients awaiting cardiac surgery, and impact postoperative outcomes. ETHICS AND DISSEMINATION: A favourable opinion was given by the Sheffield Research Ethics Committee in 2019. Trial findings will be disseminated to patients, clinicians, commissioning groups and through peer-reviewed publication. TRIAL REGISTRATION NUMBER: ISRCTN13860094.

Community health workers and health equity in low- and middle-income countries: systematic review and recommendations for policy and practice.

BACKGROUND: The deployment of Community Health Workers (CHWs) is widely promoted as a strategy for reducing health inequities in low- and middle-income countries (LMIC). Yet there is limited evidence on whether and how CHW programmes achieve this. This systematic review aimed to synthesise research findings on the following questions: (1) How effective are CHW interventions at reaching the most disadvantaged groups in LMIC contexts? and (2) What evidence exists on whether and how these programmes reduce health inequities in the populations they serve? METHODS: We searched six academic databases for recent (2014-2020) studies reporting on CHW programme access, utilisation, quality, and effects on health outcomes/behaviours in relation to potential stratifiers of health opportunities and outcomes (e.g., gender, socioeconomic status, place of residence). Quantitative data were extracted, tabulated, and subjected to meta-analysis where appropriate. Qualitative findings were synthesised using thematic analysis. RESULTS: One hundred sixty-seven studies met the search criteria, reporting on CHW interventions in 33 LMIC. Quantitative synthesis showed that CHW programmes successfully reach many (although not all) marginalized groups, but that health inequalities often persist in the populations they serve. Qualitative findings suggest that disadvantaged groups experienced barriers to taking up CHW health advice and referrals and point to a range of strategies for improving the reach and impact of CHW programmes in these groups. Ensuring fair working conditions for CHWs and expanding opportunities for advocacy were also revealed as being important for bridging health equity gaps. CONCLUSION: In order to optimise the equity impacts of CHW programmes, we need to move beyond seeing CHWs as a temporary sticking plaster, and instead build meaningful partnerships between CHWs, communities and policy-makers to confront and address the underlying structures of inequity. TRIAL REGISTRATION: PROSPERO registration number CRD42020177333 .

Socioeconomic correlates of sedentary time during pregnancy among women at risk of gestational diabetes in the UK.

Little is known about the relationship between socioeconomic position (SEP) and duration and patterning of objectively measured sedentary time (ST) among adults, especially adults at high risk of diabetes. The aim of this study was to examine cross-sectional associations of SEP with ST (total, prolonged ST, breaks in ST) and self-reported TV time among pregnant women at risk of gestational diabetes in the UK. At 20 weeks' gestation, pregnant women (n=174) wore an activPAL accelerometer and reported their usual TV time. Generalized linear mixed models were used to test associations of education, household income and area-level deprivation (separately and with mutual adjustment) with total ST, prolonged ST and breaks in ST. Logistic regression models were used to test associations between SEP indicators and high (≥2h/day) TV time. Those with the lowest education, lowest household income and highest area-level deprivation had the lowest ST and lowest prolonged ST. After mutual adjustment, area-level deprivation remained associated with total ST (ß=0.10 [0.01, 0.20]). There was an inverse association between area-level deprivation and breaks in sedentary time (exp(b)=1.11 [1.01, 1.22]). Education was the only SEP correlate of high TV time, with more of those with least education reporting high TV time; this association persisted after adjustment for household income and area-level deprivation. The association between SEP and total and prolonged ST (positive) was the opposite of the association between education and high TV time (negative) in this sample of high-risk pregnant women. These findings should inform interventions to reduce sedentary time.

Objective and subjective measurement of sedentary behavior in human adults: A toolkit.

OBJECTIVES: Objectives: Human biologists are increasingly interested in measuring and comparing physical activities in different societies. Sedentary behavior, which refers to time spent sitting or lying down while awake, is a large component of daily 24 hours movement patterns in humans and has been linked to poor health outcomes such as risk of all-cause and cardiovascular mortality, independently of physical activity. As such, it is important for researchers, with the aim of measuring human movement patterns, to most effectively use resources available to them to capture sedentary behavior. METHODS: This toolkit outlines objective (device-based) and subjective (self-report) methods for measuring sedentary behavior in free-living contexts, the benefits and drawbacks to each, as well as novel options for combined use to maximize scientific rigor. Throughout this toolkit, emphasis is placed on considerations for the use of these methods in various field conditions and in varying cultural contexts. RESULTS: Objective measures such as inclinometers are the gold-standard for measuring total sedentary time but they typically cannot capture contextual information or determine which specific behaviors are taking place. Subjective measures such as questionnaires and 24 hours-recall methods can provide measurements of time spent in specific sedentary behaviors but are subject to measurement error and response bias. CONCLUSIONS: We recommend that researchers use the method(s) that suit the research question; inclinometers are recommended for the measurement of total sedentary time, while self-report methods are recommended for measuring time spent in particular contexts of sedentary behavior.

Impact of prehabilitation on objectively measured physical activity levels in elective surgery patients: a systematic review.

OBJECTIVE: To systematically review the impact of prehabilitation on objectively measured physical activity (PA) levels in elective surgery patients. DATA SOURCES: Articles published in Web of Science Core Collections, PubMed, Embase (Ovid), CINAHL (EBSCOHost), PsycInfo (EBSCOHost) and CENTRAL through August 2020. STUDY SELECTION: Studies that met the following criteria: (1) written in English, (2) quantitatively described the effect(s) of a PA intervention among elective surgery patients prior to surgery and (3) used and reported objective measures of PA in the study. DATA EXTRACTION AND SYNTHESIS: Participant characteristics, intervention details, PA measurement, and clinical and health-related outcomes were extracted. Risk of bias was assessed following the revised Cochrane risk of bias tool. Meta-analysis was not possible due to heterogeneity, therefore narrative synthesis was used. RESULTS: 6533 unique articles were identified in the search; 21 articles (based on 15 trials) were included in the review. There was little evidence to suggest that prehabilitation is associated with increases in objectively measured PA, but this may be due to insufficient statistical power as most (n=8) trials included in the review were small feasibility/pilot studies. Where studies tested associations between objectively measured PA during the intervention period and health-related outcomes, significant beneficial associations were reported. Limitations in the evidence base precluded any assessment via meta-regression of the association between objectively measured PA and clinical or health-related outcomes. CONCLUSIONS: Additional large-scale studies are needed, with clear and consistent reporting of objective measures including accelerometry variables and outcome variables, to improve our understanding of the impact of changes in PA prior to surgery on surgical and health-related outcomes. PROSPERO REGISTRATION NUMBER: CRD42019151475.

How is television time linked to cardiometabolic health in adults? A critical systematic review of the evidence for an effect of watching television on eating, movement, affect and sleep.

OBJECTIVE: To improve our understanding of how television (TV) time is linked to cardiometabolic health among adults by systematically and critically evaluating the evidence that watching TV is associated with increased food consumption, lack of movement or negative affect or affects subsequent sleep. DESIGN: Systematic review. DATA SOURCES: Web of Science and PubMed. ELIGIBILITY CRITERIA: Studies that provided quantitative evidence on short-term associations of watching TV with dietary intake, characteristics of sitting, affect and sleep among samples of healthy adults (≥18 years old). DATA EXTRACTION AND SYNTHESIS: Study quality was assessed using the National Heart, Lung, and Blood Institute Quality Assessment Tools; studies deemed to be of low quality were excluded from the review. Due to heterogeneity of study designs and measurements, the findings were synthesised using narrative summary accompanied by custom plots. RESULTS: We identified 31 studies that met the inclusion criteria. Most of the associations reported by the studies included in this review were weak or inconsistent. There was no strong evidence to suggest that food consumption is higher while watching TV than in other contexts or that TV is a particularly 'sedentary' behaviour. Affect was less likely to be positive while watching TV than in other contexts but was not more likely to be negative. Two small studies suggest that TV may impact sleep via suppressing melatonin and delaying bedtime. CONCLUSION: There is currently no strong evidence to suggest that TV might impact cardiometabolic health via increasing food consumption, being linked with prolonged/inactive sitting, affect or subsequent sleep. Additional research is required to understand how TV fits within everyday lives and relates to eating, sitting, affect and sleep to improve our understanding of how it might impact cardiometabolic health.

Effectiveness of diet and physical activity interventions among Chinese-origin populations living in high income countries: a systematic review.

BACKGROUND: This review examines the effectiveness of diet and physical activity interventions to reduce cardiometabolic risk among Chinese immigrants and their descendants living in high income countries. The objective of this review is to provide information to help build future interventions aimed at improving diet and increasing physical activity levels among Chinese immigrants. METHODS: Outcomes included BMI, weight, waist circumference (WC), waist-hip ratio (WHR), cholesterol (LDL, HDL), systolic and diastolic blood pressure (SBP, DBP), hemoglobin A1c (HgbA1c), fasting blood glucose (FBG), and HOMA-IR. Six databases were systematically searched from database inception to date of search (February 2020). Meta-analyses used random effect models to estimate pooled effects of outcomes with 95% confidence intervals. The outcomes assessed were changes in mean outcomes (post-intervention versus baseline) among the intervention group versus control groups. RESULTS: Twenty-one articles were included for synthesis, and eight of these were included in the meta-analysis. Among children/adolescents, there were no significant effects of intervention for any of the outcomes having sufficient data for meta-analysis (BMI, WHR, SBP, and DBP). Among adults, the pooled effect including three studies showed significant changes in BMI (effect size = - 1.14 kg/m2; (95% CI: - 2.06, - 0.21), I2 = 31%). There were also significant effects of intervention among adults in terms of changes in SBP and DBP, as the pooled effect across three studies was - 6.08 mmHg (95% CI - 9.42, - 2.73), I2 = 0% and - 3.81 mmHg (95% CI: - 6.34, - 1.28), I2 = 0%, respectively. Among adults there were no other significant effects among the meta-analyses conducted (weight, WC, LDL, HgbA1c, and FBG). CONCLUSIONS: This review is the first to summarize the effectiveness of diet and physical activity interventions specifically designed for Chinese immigrants living in high income countries. There were clinically meaningful changes in BMI and blood pressure among adults, but evidence was weak for other cardiometabolic outcomes (weight, WC, LDL, HgbA1c, and FBG), and among children, there was no evidence of effect for any cardiometabolic outcomes. Given our mixed findings, more work is needed to support the design of successful interventions, particularly those targeting children and their families. TRIAL REGISTRATION: The systematic review protocol was registered in PROSPERO on December 17, 2018, the international prospective register of systematic reviews (registration number: CRD42018117842 ).

"Sit Yourself Down": Women's Experiences of Negotiating Physical Activity During Pregnancy.

Approaches to understanding why physical activity (PA) tends to decline during pregnancy are generally based on individualized behavioral models, examining "barriers" or "enablers." In contrast, we used a social practice approach to explore the ways in which women negotiate PA during pregnancy within the contexts and routines of their everyday lives. Semistructured interviews were conducted with 18 pregnant women who had been classed as being at risk of gestational diabetes. We found that leisure-time physical activities were valued as pleasurable and therapeutic, but women's roles as employees and carers for others often constrained their opportunities for leisure-time PA. Women encountered others' expectations that they should sit down and slow down. This surveillance was often resisted, as women relied on "listening to the body" as a way to negotiate PA. These findings have important implications for public health strategies or interventions designed to promote PA during pregnancy.

Associations Between Television Time and activPAL-Measured Duration and Pattern of Sedentary Time Among Pregnant Women at Risk of Gestational Diabetes in the UK.

BACKGROUND: Television (TV) time is associated with poor cardiometabolic health outcomes. This finding is commonly attributed to duration of sitting or patterns of sitting associated with high TV time, but there is very little evidence on this link. METHODS: Pregnant women (n = 167) at risk of gestational diabetes wore an activPAL accelerometer and self-reported their usual TV time in the second trimester. Generalized linear mixed models were used to compare objectively measured total sedentary time (ST), prolonged ST (bouts ≥30 min), and breaks in ST for all hours and evening hours (6 PM-11 PM) between those with high (≥2 h/d) and low TV time. RESULTS: Over all waking hours, those with high TV time had fewer breaks in ST than those with low TV time, exp(b) 0.92; 95% confidence interval, 0.86 to 0.998; there were no differences in total ST or prolonged ST between the 2 groups. Those with high TV time had significantly higher evening ST (b = 9.9; 95% confidence interval, 0.5 to 19.2); there were no differences in prolonged ST or breaks in ST during evening hours. CONCLUSIONS: These findings suggest that high TV time may be associated with higher evening ST and fewer breaks in ST. The link between TV time and sitting patterns requires further investigation.

Associations of sedentary time and self-reported television time during pregnancy with incident gestational diabetes and plasma glucose levels in women at risk of gestational diabetes in the UK.

BACKGROUND: Sedentary time is associated with increased risk of type 2 diabetes, but the association between objectively measured sedentary time and incident gestational diabetes mellitus (GDM) has not been tested. The purpose of this paper is to test associations between objectively measured sedentary time and self-reported television time during pregnancy with incident GDM and plasma glucose levels among women at high risk for GDM. METHODS: At 20 weeks' gestation, pregnant women (n = 188) in the North East of England with a risk factor for GDM wore an activPAL accelerometer and reported their usual television time. Participants underwent a standard oral glucose tolerance test at 24-28 weeks' gestation. Regression analyses were used to test for associations of total and prolonged sedentary time, breaks in sedentary time, and television time with GDM and fasting and 2-h glucose levels. Interaction terms were applied to examine whether the association between each indicator of sedentary time and glucose levels differed by GDM status. RESULTS: Total sedentary time (hours/day) was not associated with incident GDM (OR 1.00 (95%CI 1.00, 1.01)). The association between total sedentary time and glucose levels depended on GDM status: sedentary time was associated with fasting (ß = 0.16 (95%CI 0.01, 0.31)) and 2-h (ß = 0.15 (95%CI 0.01, 0.30)) glucose levels for those without GDM, while breaks in sedentary time were associated with lower fasting (ß = - 0.55 (95%CI - 0.92, - 0.17)) and 2-h (ß = - 0.40 (95%CI - 0.77, - 0.03)) glucose levels for those with GDM. Prolonged sedentary time was associated with higher fasting glucose levels regardless of GDM status (ß 0.15 (0.01, 0.30)). Television time was associated with development of GDM (OR 3.03 (95%CI 1.21, 7.96)) but not with plasma glucose levels. CONCLUSIONS: This is the first study to test associations between posture-based measures of sedentary time during pregnancy and GDM and glucose levels. The findings presented here suggest the possible importance of minimizing or breaking up sedentary time for the management of glucose levels during pregnancy, at least among women at high risk of GDM. Further research is needed to understand the different roles of total sedentary time and television time in the development of GDM.

Gender differences in walking (for leisure, transport and in total) across adult life: a systematic review.

BACKGROUND: The aim of this systematic review was to examine gender differences in walking for leisure, transport and in total in adults living in high-income countries, and to assess whether gender differences in walking practices change across the life-course. METHODS: A systematic literature search was conducted of publications dated 1995 to 2015. Papers providing quantitative data on participation in walking of both men and women aged at least 18 years in a high-income country were screened for the quality of the data on gender differences in walking. Data were extracted and results were synthesised using forest plots and narrative summary. RESULTS: Thirty-six studies were included in the review: 18 reported on walking for leisure, 16 on walking for transport (in total, or for particular purposes), and 14 on total walking. Most (33) studies provided data comparing the proportion of men and women who walked (at all or for a minimum duration) over a defined period, usually one week. There was consistent evidence that more women than men walk for leisure, although effect sizes were small. However, this effect varies by age: more younger women than younger men walk for leisure, but the gender difference diminishes with age and appears to reverse in the oldest age groups. Taking all ages together, there was no consistent gender difference in walking for transport or in total walking, although the small number of studies reporting on walking to undertake errands suggested that more women than men walk for this purpose. CONCLUSIONS: While there is little evidence that levels of total walking consistently vary by gender, our findings suggest that there are consistent gender differences in participation in walking for some purposes, including for leisure, and that there are gender differences in the impact of age on walking. We conclude that more research is needed to improve our understanding of how walking fits into the lives of women and men across the life-course, especially in relation to gender differences in the impact of aging on walking. PROSPERO REGISTRATION: PROSPERO registration number: CRD42015025961 .

Human footprint variation while performing load bearing tasks.

Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint's maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations.

Energetic consequences of human sociality: walking speed choices among friendly dyads.

Research has shown that individuals have an optimal walking speed-a speed which minimizes energy expenditure for a given distance. Because the optimal walking speed varies with mass and lower limb length, it also varies with sex, with males in any given population tending to have faster optimal walking speeds. This potentially creates an energetic dilemma for mixed-sex walking groups. Here we examine speed choices made by individuals of varying stature, mass, and sex walking together. Individuals (N = 22) walked around a track alone, with a significant other (with and without holding hands), and with friends of the same and opposite sex while their speeds were recorded every 100 m. Our findings show that males walk at a significantly slower pace to match the females' paces (p = 0.009), when the female is their romantic partner. The paces of friends of either same or mixed sex walking together did not significantly change (p>0.05). Thus significant pace adjustment appears to be limited to romantic partners. These findings have implications for both mobility and reproductive strategies of groups. Because the male carries the energetic burden by adjusting his pace (slowing down 7%), the female is spared the potentially increased caloric cost required to walk together. In energetically demanding environments, we will expect to find gender segregation in group composition, particularly when travelling longer distances.