Current Research

Maternal energy metabolism in endurance athletes during pregnancy. In pregnancy, mothers face increasing energy demands to support fetal growth. Previous studies have proposed a limit to sustained energy metabolism in humans (~2.5× basal metabolic rate, BMR; kilocalories/day). It is unclear if pregnancy, particularly coupled with high levels of physical activity, pushes maternal energy expenditure beyond the metabolic limit. We hypothesize that there is a metabolic limit to maternal energy expenditure, ~2.5× preconception BMR, which is not surpassed during highly active pregnancies. We expect physiological trade-offs within a limited energy budget impact maternal and fetal health outcomes. We are testing these hypotheses through a prospective cohort study of endurance athletes who plan to continue training during their pregnancies. Data collection will conclude in fall 2024.

  • Sadhir, S., McGrosky, A., Swanson, Z.S., Tomechko, K., & Pontzer, H. (2024). Maternal metabolic limits in endurance athletes during pregnancy. 49th Annual Meeting of the Human Biology Association (p.66), Los Angeles, CA [podium].

Physical activity patterns and health outcomes during pregnancy. Energy investment in high levels of physical activity likely trades off with energy investment in reproduction to influence fecundity and pregnancy outcomes. U.S. pregnancy guidelines recommend 150 mins/week of exercise for positive pregnancy outcomes, including lower likelihoods of hypertension, excessive gestational weight gain, and macrosomia. We predict that women with higher physical activity will report lower fecundity and a higher incidence of menstrual disorders. We also predict that women with higher physical activity during pregnancy will reduce their activity over gestation, and report lower incidences of gestational metabolic disorders. We implemented two online survey recruiting women to self-report measures of fecundity, physical activity patterns, perceptions of physical activity, and health outcomes during their last pregnancies (n=1088). Data analysis is ongoing.

  • Tomechko, K., Sadhir, S., & Pontzer, H. (2024). Physical activity patterns, perceived barriers, and health outcomes during pregnancy for women in high-income countries. 49th Annual Meeting of the Human Biology Association (p.11), Los Angeles, CA [poster].
  • Sadhir, S., & Pontzer, H. (2022). Survey of exercise behavior and pregnancy outcomes in highly active women. 91st Annual Meeting of the American Association of Biological Anthropologists (p.158), Denver, CO [poster].

Physical activity and pregnancy norms among Daasanach semi-nomadic pastoralist women. In subsistence populations, high physical activity workloads are typically maintained throughout pregnancy. Market integration shifts patterns of physical activity, often resembling industrialized populations, with more time allocated to sedentary behavior and less time allocated to physical activity. Daasanach semi-nomadic pastoralists living in arid northern Kenya face lifestyle heterogeneity due to the emergence of a market center. We examine how Daasanach women (n=93) manage the energetic demands of pregnancy with subsistence labor tasks and how distance to the market is related to variation in energetic demands, physical activity, and coping strategies. This study was undertaken as part of the Daasanach Health & Life History Project (Koobi Fora Field School) during the summer 2022 field season. Publication in prep.

  • Sadhir, S., McGrosky, A., Ford, L.B., Nzunza, R., Wemanya, S.N., Mashaka, H., Kinyanjui, R., Ndiema, E., Braun, D.R., Rosinger, A.Y., & Pontzer, H. (2023). Physical activity and pregnancy norms among Daasanach women in Northern Kenya. 48th Annual Meeting of the Human Biology Association (p.45), Reno, NV [podium].

Reproductive energetics & neuroendocrinology of ruffed & ring-tailed lemurs. Maternal strategies during pregnancy, lactation, and infant dependency differ greatly between primate species, yet energetic costs of these behaviors are not well understood and have rarely been objectively measured. In addition, the role of oxytocin in mating, bonding, and parental care is not well understood in strepsirrhines. To improve our understanding of energetic costs and hormone changes associated with reproduction, we are investigating total energy expenditure, accelerometry-derived physical activity, and oxytocin concentration over gestation, lactation, and weaning in two lemur species of similar body size at the Duke Lemur Center: ring-tailed lemurs (Lemur catta) and ruffed lemurs (Varecia variegata and V. rubra, grouped as Varecia spp. for the purpose of this study). This study is in collaboration with Allie Schrock and Dr. Christine Drea of Duke University. Data collection will conclude in summer 2024.

Energy availability and fertility across human populations. We reviewed how energetic factors may influence female reproduction and presented an analysis of age at first reproduction and interbirth interval trends across a diverse, global sample representing 44 countries and two natural fertility populations. We found that alongside economic and cultural influences on fertility, women in energy-rich, industrialized populations are capable of greater reproductive output than women in energy-stressed populations.

  • Sadhir, S., & Pontzer, H. (2023). Impact of energy availability and physical activity on variation in fertility across human populations. Journal of Physiological Anthropology, 42(1), 1.
  • Sadhir, S., & Pontzer, H. (2021). Interbirth interval and age at first reproduction in populations with disparate energy status. 90th Annual Meeting of the American Association of Physical Anthropologists (p.91), virtual format [poster and panel discussion].


Graduate Mentorship of Undergraduate Honors Theses

  • Parker, C. H., Sadhir, S., Swanson, Z., McGrosky, A., Hinz, E., Urlacher, S. S., & Pontzer, H. (2023). Effect of influenza vaccination on resting metabolic rate and c-reactive protein concentrations in healthy young adults. PLOS ONE, 18(12), e0295540.
  • Klasson, C. L., Sadhir, S., & Pontzer, H. (2022). Daily physical activity is negatively associated with thyroid hormone levels, inflammation, and immune system markers among men and women in the NHANES dataset. PLoS One, 17(7), e0270221.


Undergraduate Research

Baboon (Papio spp.) phenotypic diversity and health in historical museum collections. I undertook this project as part of an NSF REU (Natural History Research Experiences) at the Smithsonian National Museum of Natural History (Washington, DC) under the mentorship of Dr. Sabrina Sholts and Dr. Andrea Eller.

  • Sadhir, S., Eller, A. R., Canington, S. L., & Sholts, S. B. (2022). Investigating factors of metabolic bone disease in baboons (Papio spp.) using museum collections. American Journal of Biological Anthropology, 177(3), 489-500.

Human hunting adaptations at Wadi Madamagh, Jordan at the peak of the Last Glacial Maximum. I undertook this zooarchaeological faunal analysis for my Honors thesis project at the University of Connecticut, under the advisement of Dr. Natalie Munro.

  • Sadhir, S., al-Nahar, M., Olszewski, D. I., Petrillo, A., & Munro, N. D. (2020). Human hunting adaptations at Wadi Madamagh, Jordan at the peak of the Last Glacial Maximum. Journal of Archaeological Science: Reports, 34, 102661.

©2024 – Srishti Sadhir