Background: There is limited research examining the intensity of yoga and intensity variations between different styles. The purpose of this review is to examine the intensity of yoga based on different physiologic responses both between different yoga styles and within styles of yoga. Methods: Articles were searched for on the PubMed database in early 2019. Inclusion criteria were as follows: (1) written in English, (2) cite a specific style of yoga and include whole yoga session, and (3) measure metabolic or heart rate response. Results: Ten articles were reviewed; articles reported oxygen consumption (n = 1), heart rate (n = 4), or both variables (n = 5). Yoga styles assessed included ashtanga (n = 2), Bikram (n = 3), gentle (n = 1), hatha (n = 3), Iyengar (n = 1), power (n = 1), and vinyasa (n = 1). Oxygen consumption commonly categorized yoga as a light-intensity activity, while heart rate responses classified different yoga into multiple intensities. Conclusion: This review demonstrates that large differences in intensity classifications are observed between different styles of yoga. Furthermore, metabolic and heart rate responses can be variable, leading to inconsistent intensity classifications. This is likely due to their nonlinear relationship during yoga. Thus, it is imperative that the field of yoga research works together to create a standard for reporting yoga.