Iñigo San Millán

University of Colorado | UCD · Division of Endocrinology, Metabolism and Diabetes

Herein we use lessons learned in exercise physiology and metabolism to propose that augmented lactate production ("lactagenesis)", initiated by gene mutations, is the reason and purpose of the Warburg effect and that dysregulated lactate metabolism and signaling are key elements in carcinogenesis. Lactate producing ("lactagenic") cancer cells are c...

Unlabelled: Glycogen storage is essential for exercise performance. The ability to assess muscle glycogen levels should be an important advantage for performance. However, skeletal muscle glycogen assessment has only been available and validated through muscle biopsy. We have developed a new methodology using high-frequency ultrasound to assess sk...

Critically ill patients experience hypermetabolism increas ing substrate utilization, especially glucose oxidation. Glycogen is the main source of glucose in the body, being 85% and 15% stored in skeletal muscle and liver respectively. Since glycogen stores are limited we evaluated the hypothesis that critical illness could be associated with glyco...

Over the last 10 years we have significantly reduced hospital mortality from sepsis and critical illness. However, the evidence reveals that over the same period we have tripled the number of patients being sent to rehabilitation settings. Further, given that as many as half of the deaths in the first year following ICU admission occur post ICU dis...

OBJECTIVES: Mitochondrial dysfunction is a characteristic of insulin resistance (IR) and type 2 diabetes (T2D) characterized by a poor fat oxidation and elevated blood lactate levels. Since both fatty acids and lactate are mitochondrial substrates, my aim was to measure mitochondrial function by means of measuring fat and lactate oxidation during e...

Exercise intolerance is a major manifestation of post-acute sequelae of severe acute respiratory syndrome coronavirus infection (PASC, or “long-COVID”). Exercise intolerance in PASC is associated with higher arterial blood lactate accumulation and lower fatty acid oxidation rates during graded exercise tests to volitional exertion, suggesting alter...

To characterize molecular profiles of exertion in elite athletes during cycling, we performed metabolomics analyses on blood isolated from twenty-eight international-level elite World Tour professional male athletes from a Union Cycliste Internationale (UCI) World Team taken before and after a graded exercise test (GXT) to volitional exhaustion and...

Thiamine is present in many foods and is well recognised as an essential nutrient critical for energy metabolism. While thiamine deficiency is commonly recognised in alcoholism, it can present in many other settings where it is often not considered and goes unrecognised. One challenging aspect to diagnosis is that it may have varied metabolic, neur...

Introduction Lactate is an important signaling molecule with autocrine, paracrine and endocrine properties involved in multiple biological processes including regulation of gene expression and metabolism. Levels of lactate are increased chronically in diseases associated with cardiometabolic disease such as heart failure, type 2 diabetes, and cance...

Background: Stimulator of interferon (IFN) genes (STING) is a protein that promotes type I IFN production essential for T-cell activation. In this study, we aim to characterize STING expression comprehensively using The Cancer Genome Atlas (TCGA) database, cell lines, and patient tumor samples stained with immunohistochemistry. Methods: Two coho...

Purpose of review: Addressing the reduced quality of life that affects ICU survivors is the most pressing challenge in critical care medicine. In order to meet this challenge, we must translate lessons learnt from assessing and training athletes to the clinical population, utilizing measurable and targeted parameters obtained during cardiopulmonar...

The field of metabolism and cellular bioenergetics has been object of great interest to many scientists including multiple Nobel laureates. Until recently, the main developments in the understanding of mitochondrial bioenergetics came from the field of exercise metabolism. However, this knowledge has finally spilled over into the field of health an...

In our paper published in this journal, we present a pilot study application of a novel way to “indirectly assess” skeletal muscle glycogen based on the methodology that we developed though high-frequency skeletal muscle ultrasound [...]

Abstract Obesity and metabolic syndrome are strongly associated with cancer, and these disorders may share a common mechanism. Recently, fructose has emerged as a driving force to develop obesity and metabolic syndrome. Thus, we assume that fructose may be the mechanism to explain why obesity and metabolic syndrome are linked with cancer. Clinical...

The study of elite athletes provides a unique opportunity to define the upper limits of human physiology and performance. Across a variety of sports, these individuals have trained to optimize the physiological parameters of their bodies in order to compete on the world stage. To characterize endurance capacity, techniques such as heart rate monito...

Skeletal muscle glycogen (SMG) stores in highly glycolytic activities regulate muscle contraction by controlling calcium release and uptake from sarcoplasmic reticulum, which could affect muscle contraction. Historically, the assessment of SMG was performed through invasive and non-practical muscle biopsies. In this study we have utilized a novel m...

Carbohydrate intake enhances endurance exercise performance, and different levels of performance dictate specific intake amounts. With low-carbohydrate diets remaining popular among a variety of team, strength, and endurance sports, it is important to highlight the need for carbohydrate in relation to endurance events that require the use of all en...

To assess differences in carbohydrate, sodium, and fluid intake across sub-9 hour to 12 hour finishers of the Leadville MTB 100 Endurance Race.

Lactate is a ubiquitous molecule in cancer. In this exploratory study, our aim was to test the hypothesis that lactate could function as an oncometabolite by evaluating whether lactate exposure modifies the expression of oncogenes, or genes encoding transcription factors, cell division, and cell proliferation in MCF7 cells, a human breast cancer ce...

Morris, KL, Widstrom, L, Goodrich, J, Poddar, S, Rueda, M, Holliday, M, San Millian, I, and Byrnes, WC. A retrospective analysis of collegiate athlete blood biomarkers at moderate altitude. J Strength Cond Res 33(11): 2913-2919, 2019-Blood biomarkers are used to assess overall health and determine positive/negative adaptations to training/environme...

The field of sports medicine and performance has undergone an important transformation in the past years where the scientific approach is becoming increasingly more important for teams and athletes. Physical and physiological fitness, nutrition, fatigue and recovery, as well as injury prevention are key elements of the scientific monitoring of athl...

Background: Increased muscle mitochondrial mass is characteristic of elite professional endurance athletes (PAs), whereas increased blood lactate levels (lactatemia) at the same absolute submaximal exercise intensities and decreased mitochondrial oxidative capacity are characteristics of individuals with low aerobic power. In contrast to PAs, pati...

Purpose of review: We have significantly improved hospital mortality from sepsis and critical illness in last 10 years; however, over this same period we have tripled the number of 'ICU survivors' going to rehabilitation. Furthermore, as up to half the deaths in the first year following ICU admission occur post-ICU discharge, it is unclear how man...

Type 1 diabetes is a challenging condition to manage for various physiological and behavioural reasons. Regular exercise is important, but management of different forms of physical activity is particularly difficult for both the individual with type 1 diabetes and the health-care provider. People with type 1 diabetes tend to be at least as inactive...

Objectives: Creatine kinase (CK) is a sensitive enzyme marker for muscle damage in athletes. Elevated CK levels have been reported in many endurance physical activities. The consequence and possible long-term sequela of the CK elevation in athletes is unknown. There is a paucity of literature stating actual numerical values of CK associated with c...

video #2 used with permission of Wes Ely and http://www.icudelerium.org.

video #1 used with permission of Wes Ely and http://www.icudelerium.org.

Despite increased ultramarathon participation in recent years, little is known about causes of race incompletion. This study surveyed runners of three 161-168 km ultramarathons in Europe and North America to explore characteristics and issues that affected race performance. Determine human and environmental factors related to failure to complete ul...

The purpose of this paper was to assess the feasibility of Micro-Mobile Compression® (MMC) on lactate clearance following exhaustive exercise and on subsequent exercise performance. Elite male cyclists were randomized to MMC (n = 8) or passive recovery (control, n = 8). MMC is incorporated into a sandal that intermittently compresses the venous ple...

BACKGROUND: Proper glycogen storage is of great importance for athletic performance. Multiple studies show the positive correlation between glycogen storage and performance. Nevertheless, glycogen assessment is difficult to determine due to the invasive and impractical nature of muscle biopsies. Therefore, it is difficult to identify suboptimal gly...

PURPOSE: To assess the effects of a sprint distance duathlon laboratory simulation on FAToxr and CHOoxr. METHODS: 8 national level duathletes performed two incremental laboratory tests until exhaustion on a cycle ergometer (Initial workload: 60 W, stages: 30 W·min-1) and on a treadmill (Initial workload: 5 km·h-1, stages: 1 km·h-1) respectively to...