How Cold, Altitude and Training Shape Human Energy Supply

How the human body generates and manages its energy supply under extreme conditions is a question that sits at the intersection of sports science, environmental physiology and military operational medicine. A new editorial published in Frontiers in Sports and Active Living on 20 October 2026 summarizes a dedicated Frontiers Research Topic titled “The relationship between human energy supply and environmental and training factors,” bringing together contributions from research institutions across China, Ireland, Greece and Sweden. The editorial, authored by Jichao Sun of China University of Geosciences in Beijing, frames energy supply as a cross-cutting concern that touches everyone from Winter Olympic athletes preparing for cold adaptation to soldiers marching under load in heat and high humidity.

The core premise of the Research Topic is that energy homeostasis under complex conditions directly affects athletic performance, operational efficiency and personal safety. Environmental factors such as temperature, barometric pressure, altitude, oxygen content and slope significantly alter human energy expenditure and physical performance. Cold environments force the body to expend more energy to maintain core body temperature, high-altitude hypoxia alters aerobic metabolism and energy supply pathways, and increased slope significantly raises energy demand. In military settings, conditions such as heat, hypoxia and prolonged load-carriage marches place higher demands on soldiers’ physical fitness, combat effectiveness and logistics support.

The editorial identifies a set of persistent bottlenecks that constrain progress in this field. Ethical and safety constraints in extreme scenarios make it difficult to design experiments that truly replicate the harshest conditions humans face. Real-world data are hard to obtain, and the multi-factor interaction mechanisms governing energy supply have not yet been systematically elucidated. These limitations, the editorial argues, remain urgent problems for researchers attempting to translate laboratory findings into guidance for athletes and military planners.

Determining maximal human energy supply capacity has practical value on both sides of the civilian-military divide. For athletes, it helps optimize training programs and improve competitive performance. For military applications, it provides a basis for assessing operational efficiency in special scenarios and for formulating combat deployment and logistics support plans. The Research Topic was therefore established around this interdisciplinary frontier to promote dialogue among basic mechanisms, assessment methods and translational applications.

The Research Topic called for submissions across five research directions. The first concerns the effects of training methods on energy supply mechanisms. Within this direction, Wang and colleagues revealed the metabolic mechanism by which high-intensity interval training promotes adipose tissue browning through the IL-27/p38 MAPK-PGC-1α pathway, a signaling cascade linking an exercise stimulus to metabolic remodeling of fat tissue. Grivas and colleagues reviewed negative-split pacing as a trainable strategy, while Lin and colleagues used the PCr-La-O₂ framework to estimate cumulative endpoints and reconstruct the energy-system contributions over 500-meter segments in 2,000-meter rowing ergometer tests. Zeng and colleagues validated the effects of severity-adapted graded exercise rehabilitation on inflammation and functional capacity in patients with acute exacerbations of chronic obstructive pulmonary disease.

The second direction addresses the role of training equipment in optimizing energy utilization and enhancing adaptability. The contributions here span monitoring tools and laboratory apparatus: Grivas and colleagues discussed heart rate variability, GPS and session-RPE monitoring tools; Lin and colleagues used a rowing ergometer together with an endpoint test protocol; and Zeng and colleagues employed graded exercise rehabilitation equipment with intensity-adapted strategies. The third direction examines the mechanisms linking environmental factors to energy expenditure and physical performance. Fang and colleagues analyzed serum metabolic profiles associated with physical fitness in healthy men in cold environments, finding that amino acid metabolism, especially the histidine and tryptophan pathways, was associated with fitness differences. Ryan and colleagues conducted a qualitative analysis of Marathon des Sables ultramarathon runners, presenting interactions among nutritional practices, gastrointestinal symptoms and psychological challenges in an extreme desert environment.

The fourth direction focuses on evaluation methods and safety thresholds for energy supply limits in special environments. The editorial notes that the PCr-La-O₂ energy-system estimation method, serum metabolic markers and severity-adapted safe-intensity strategies provide methodological references for this purpose. The fifth direction concerns the translation of energy supply research into sports, military and other fields, where nutritional recommendations, training models, rehabilitation protocols, obesity intervention strategies and pacing monitoring methods collectively demonstrate translational value.

The methods represented across the collection are notably diverse. They include metabolomics, which profiles small molecules in serum to reveal metabolic pathway activity; ergometer testing, which quantifies energy-system contributions under controlled laboratory conditions; and qualitative investigation, which captures the lived experience of athletes in extreme environments. The settings covered extend to cold, high altitude and desert conditions, reflecting the breadth of environments in which energy supply becomes a limiting factor for human performance.

By author affiliation, the papers span four countries. Chinese institutions include Zunyi Medical University, Yangzhou University, the Jiangsu Institute of Sports Science, Jimei University, Xianyang Yucai Tianjiabing Middle School, China Agricultural University, the Institute of Environmental and Operational Medicine of the Academy of Military Medical Sciences, and Peking University Third Hospital. Other contributing institutions include Atlantic Technological University in Ireland, the Hellenic Naval Academy in Greece and the Karolinska Institute in Sweden, with approximately 11 institutions listed in total.

The editorial concludes that the Research Topic comprehensively addressed its five solicited directions, focusing on energy metabolism and physical adaptation under extreme environments such as cold, high altitude, desert and high humidity, as well as on training methods, training equipment, evaluation thresholds and translation of findings. The editors express the view that the special issue will maintain high visibility over the long term, and they identify interdisciplinary integration as the path forward: deepening ongoing dialogue among sports science, environmental medicine and military operational medicine to provide academic support for improving athletic performance and military operational effectiveness.

Subject of Research: An editorial summarizing a Frontiers Research Topic on human energy supply under environmental and training stressors in sport and military contexts.

Article Title: Editorial: The relationship between human energy supply and environmental and training factors

Article References: Sun, J. (2026). Editorial: The relationship between human energy supply and environmental and training factors. Frontiers in Sports and Active Living, 8, 2017019. https://doi.org/10.3389/fspor.2026.2017019

Image Credits: AI Generated

DOI: 10.3389/fspor.2026.2017019

Keywords: human energy supply, environmental physiology, exercise physiology, cold environments, high altitude, hypoxia, military operational medicine, metabolomics, HIIT, rowing ergometer, ultramarathon, translational research