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BackgroundThere are currently over 1000 exercise apps for mobile devices on the market. These apps employ a range of features, from tracking exercise activity to providing motivational messages. However, virtually nothing is known about whether exercise apps improve exercise levels and health outcomes and, if so, the mechanisms of these effects. ObjectiveOur aim was to examine whether the use of exercise apps is associated with increased levels of exercise and improved health outcomes. We also develop a framework within which to understand how exercise apps may affect health and test multiple models of possible mechanisms of action and boundary conditions of these relationships. Within this framework, app use may increase physical activity by influencing variables such as self-efficacy and may help to overcome exercise barriers, leading to improved health outcomes such as lower body mass index (BMI). MethodsIn this study, 726 participants with one of three backgrounds were surveyed about their use of exercise apps and health: (1) those who never used exercise apps, (2) those who used exercise apps but discontinued use, and (3) those who are currently using exercise apps. Participants were asked about their long-term levels of exercise and about their levels of exercise during the previous week with the International Physical Activity Questionnaire (IPAQ). ResultsNearly three-quarters of current app users reported being more active compared to under half of non-users and past users. The IPAQ showed that current users had higher total leisure time metabolic equivalent of task (MET) expenditures (1169 METs), including walking and vigorous exercise, compared to those who stopped using their apps (612 METs) or who never used apps (577 METs). Importantly, physical activity levels in domains other than leisure time activity were similar across the groups. The results also showed that current users had lower BMI (25.16) than past users (26.8) and non-users (26.9) and that this association was mediated by exercise levels and self-efficacy. That relationship was also moderated by perceived barriers to exercise. Multiple serial mediation models were tested, which revealed that the association between app use and BMI is mediated by increased self-efficacy and increased exercise. ConclusionsExercise app users are more likely to exercise during their leisure time, compared to those who do not use exercise apps, essentially fulfilling the role that many of these apps were designed to accomplish. Data also suggest that one way that exercise apps may increase exercise levels and health outcomes such as BMI is by making it easier for users to overcome barriers to exercise, leading to increased self-efficacy. We discuss ways of improving the effectiveness of apps by incorporating theory-driven approaches. We conclude that exercise apps can be viewed as intervention delivery systems consisting of features that help users overcome specific barriers.

In recent years, a new generation of “digital credit” products have transformed the consumer lending landscape in many low- and middle-income countries. Offering short- term, high-interest loans via mobile phones or other digital platforms, these products have become wildly popular. This article reviews the small but emerging evidence on the welfare impacts of digital credit. These studies document very high rates of takeup – well in excess of traditional microcredit – despite the fact that customers often do not understand the terms of their loans. Overall, there is little evidence that access to credit has consistent positive impacts on borrower welfare, though two impact evaluations document positive effects on resilience and subjective well-being, respectively. No study finds statistically significant negative impacts of digital credit.

Digital credit has expanded rapidly in Africa, mostly in the form of short-term, high-interest loans offered via mobile money. Loan terms are often opaque and consumer financial literacy is low, providing opportunities for predatory lending. A regression discontinuity analysis shows no negative effect of access to digital loans on financial well-being, but the majority of borrowers fail to repay on time and incur high late fees. We randomize exposure to a short phone-based financial literacy intervention. The intervention improved knowledge and marginally improved loan repayment but increased loan demand, increasing overall default risk.

We quantify the effect of market disruptions due to COVID-19 on the lives of householdsin rural areas of Liberia and Malawi, utilizing panel data from phone surveys that were implemented as part of a randomized cash transfer experiment. The surveys began collection several months before the pandemic and have continued throughout it. The household survey included a consistent set of internationally accepted and validated questions on food security (the householddietary diversity score, the household hunger scale, and the food consumption score). In both countries, market activity was severely disrupted and we observe large declines in income among market vendors, but we find no evidence of declines in food security for households in the short run. Even though we observe no adverse effects of the lockdowns on food securityamong the control group, cash transfers improved dietary quality and quantity over the low levels observed at baseline.

Genome-scale metabolic models (GEMs) are valuable tools to study metabolism and provide a scaffold for the integrative analysis of omics data. Researchers have developed increasingly comprehensive human GEMs, but the disconnect among different model sources and versions impedes further progress. We therefore integrated and extensively curated the most recent human metabolic models to construct a consensus GEM, Human1. We demonstrated the versatility of Human1 through the generation and analysis of cell- and tissue-specific models using transcriptomic, proteomic, and kinetic data. We also present an accompanying web portal, Metabolic Atlas (https://www.metabolicatlas.org/), which facilitates further exploration and visualization of Human1 content. Human1 was created using a version-controlled, open-source model development framework to enable community-driven curation and refinement. This framework allows Human1 to be an evolving shared resource for future studies of human health and disease.

Distributing subsidized health products through existing health infrastructure could substantially and cost-effectively improve health in sub-Saharan Africa. There is, however, widespread concern that poor governance - in particular, limited health worker accountability - seriously undermines the effectiveness of subsidy programs. We audit targeted bednet distribution programs to quantify the extent of agency problems. We find that around 80% of the eligible receive the subsidy as intended, and up to 15% of subsidies are leaked to ineligible people. Supplementing the program with simple financial or monitoring incentives for health workers does not improve performance further and is thus not cost-effective in this context.