Understanding the genetic structure of Native American populations is important to clarify their diversity, demographic history, and to identify genetic factors relevant for biomedical traits. Here, we show a demographic history reconstruction from 12 Native American whole genomes belonging to six distinct ethnic groups representing the three main described genetic clusters of Mexico (Northern, Southern, and Maya). Effective population size estimates of all Native American groups remained below 2,000 individuals for up to 10,000 years ago. The proportion of missense variants predicted as damaging is higher for undescribed (~ 30%) than for previously reported variants (~ 15%). Several variants previously associated with biological traits are highly frequent in the Native American genomes. These findings suggest that the demographic and adaptive processes that occurred in these groups shaped their genetic architecture and could have implications in biological processes of the Native Americans and Mestizos of today.

Objectives: Our purpose was to explore the levels of cardiorespiratory fitness (CRF) and the relationship between CRF, physical activity, and other physical traits in traditional and nontraditional Tarahumara, and Mestizo adolescents from Sierra Tarahumara, Mexico. Methods: A sample of 87 adolescents aged 16.9 ± 1.2 years (mean ± SD) performed the Margaria step test to quantify CRF. Physical activity was estimated using the International Physical Activity Questionnaire. Blood pressure (BP) and anthropometric measures were taken to estimate body composition and other physical characteristics. Results: Traditional Tarahumara showed higher levels of CRF than nontraditional Tarahumara and Mestizo adolescents (F = 5.5, p = .006). The time allotted to sedentary activities was higher in the Mestizo and nontraditional Tarahumara (χ 2 = 10.17, p = .006). In nontraditional Tarahumara, adiposity was associated with CRF reduction (r 2 = −.63, p = .00), while vigorous physical activities were positively associated with CRF (r 2 = .43, p = .03) and negatively associated with the z-score of body fat (r 2 = −.42 p = .03). Finally, CRF was negatively associated with fat percentage (r 2 = −.27, p = .00) and systolic blood pressure (r 2 = −.09, p = .04) in the Mestizo. In this group, walking activities (r 2 = −.25, p = .003) and total physical activity score (r 2 = −.11, p = .03) had a positive association with the CRF, while moderate activities had a negative association with the body mass index (r 2 = .09, p = .04), and vigorous activities were negatively associated with body weight (r 2 = .11, p = .03). Conclusions: In the sampled nontraditional Tarahumara and Mestizo adolescents, moderate and vigorous physical activities were important factors in determining levels in CRF, fat percentage, and other health parameters. 1 | INTRODUCTION The Raramuri, best known as Tarahumara, are an indigenous people of North America that share the southwest territory of Chihuahua in Mexico's western Sierra Madre, called "Sierra Tarahumara," with other native groups such as the Pima, the Guarijio, and the Tepehuan (Gotés