Karsten Koehler

• Ph.D.
• Professor (Assistant) at Technical University of Munich

Background Sprint performance may be crucial for athletes in sprint and endurance sports. In this regard, the maximal glycolytic rate (νLamax) is a variable within Mader’s model of metabolism that is commonly tested in a 15-s all-out sprint test. The product of lactate accumulation (ΔLa) and lactate distribution space approximated by fat-free mass...

Purpose The purpose was to evaluate the individual and combined use of the Low Energy Availability in Females Questionnaire (LEAF-Q) and the Brief Eating Disorder in Athletes Questionnaire (BEDA-Q) to detect clinical indicators associated with Relative Energy Deficiency in Sport (REDs). Methods In this cross-sectional study, 50 female endurance at...

While the effect of time-of-day (morning versus evening) on hormones, lipids and lipolysis has been studied in relation to meals and exercise, there are no studies that have investigated the effects of time-of-day on ice bath induced hormone and lipidome responses. In this crossover-designed study, a group of six women and six men, 26 ± 5 years old...

Background The global prevalence of the metabolic disease Type 2 Diabetes (T2D) is increasing. Risk factors contributing to the development of T2D include overweight and obesity, lack of physical activity (PA), and an unhealthy diet. In addition, the gut microbiota has been shown to affect metabolic regulation. Since T2D is preventable, efforts sho...

EINLEITUNG: Sport führt häufig zu einer kompensatorischen Erhöhung der Nahrungsaufnahme. Mögliche Modulatoren der Energiekompensation sind Zeitpunkt und Stoffwechselzustand des Trainings, allerdings werden die Effekte häufig vermischt. Ziel war es die Effekte von Tageszeit (morgens/abends) und Stoffwechselzustand (nüchtern/nicht nüchtern) auf die s...

While the effect of time-of-day (morning versus evening) has been studied in relation to meals and exercise, there are no studies that investigate the effects of time-of-day on an ice bath. In this crossover-designed study, we recruited a homogenous group of six women and six men for an ice bath (8–12°C for 5 min) in the morning and evening. Venous...

BACKGROUND: Predicting individual weight loss responses to lifestyle interventions is challenging but might help practitioners and clinicians select the most promising approach for each individual. OBJECTIVE: The primary aim of this study was to develop machine learning models to predict individual weight loss responses using only variables known b...

Exercise has a significant impact on the cardiovascular (CV) health of children and adolescents, with resultant alterations in CV structure and function being evident, even at an early age. Engagement in regular, moderate physical activity (PA) is associated with long-term CV health benefits and a reduced risk of CV disease and mortality later in l...

Objective This cross-sectional study aimed to investigate the role of low energy availability (LEA) in the interplay between depression and disordered eating/eating disorders (DE/EDs) among female athletes. The International Olympic Committee consensus statement on Relative Energy Deficiency in Sport (REDs) identified depression as both an outcome...

Background & Aims: Adequate energy availability is essential for the body to maintain its physiological functions and achieve optimal health, especially among athletes. Unfortunately, low energy availability (LEA) is common among athletes, and it has been associated with impairments in health and performance. In contrast, an energy-restricted diet...

Aim A 15-s all-out sprint cycle test (i.e., νLamax-test) and the post-exercise change in capillary blood lactate concentration is an emerging diagnostic tool that is used to quantify the maximal glycolytic rate. The goal of this study was to determine the relation between 15 s-work, change in capillary blood lactate concentration (∆La) and body com...

Based on Mader's mathematical model, the rate of capillary blood lactate concentration (νLamax) following intense exercise is thought to reflect the maximal glycolytic rate. We aimed to investigate the reliability of important variables of Mader's model (i.e. power output, lactate accumulation, predominant phosphagen contribution time frames (tPCr)...

Introduction Evidence indicates that sphingolipid accumulation drives complex molecular alterations promoting cardiometabolic diseases. Clinically, it was shown that sphingolipids predict cardiometabolic risk independently of and beyond traditional biomarkers such as low-density lipoprotein cholesterol. To date, little is known about therapeutic mo...

OBJECTIVE: Continuous glucose monitoring (CGM) shows promise in optimizing the assessment and monitoring of ingestive activity (IA; i.e., consumption of calorie-containing foods and beverages). We conducted a scoping review of publications examining the performance of CGM-based approaches to automatically detect IA. We aimed to answer three questio...

The German Report Card on Physical Activity for Children and Adolescents 2022 provides a summary and a comprehensive evaluation of physical activity levels and correlated indicators using the Active Healthy Kids Canada grading framework. The 2022 German Report Card, established by the Active Healthy Kids Germany (AHK Germany) expert panel, describe...

Purpose Stable isotope ratios of nitrogen (δ¹⁵N) have previously been shown to increase in human hair during periods of catabolism. The goal of this study was to assess changes in δ¹⁵N in urinary urea (δ¹⁵Nurea) and Δ¹⁵N during a short-term controlled energy deficit. Methods We analyzed samples from 6 recreationally active men (25 ± 1 years, BMI:...

Background Accurate dietary assessment remains a challenge, particularly in free-living settings. Continuous glucose monitoring (CGM) shows promise in optimizing the assessment and monitoring of ingestive activity (IA, i.e., consumption of calorie-containing foods/beverages), and it might enable administering dietary Just-In-Time Adaptive Intervent...

Female endurance athletes are at high risk for developing Relative Energy Deficiency in Sport (REDs), resulting in symptoms such as menstrual dysfunction and gastrointestinal (GI) problems. The primary aim of this study was to investigate effects of the FUEL (Food and nUtrition for Endurance athletes—a Learning program) intervention consisting of w...

Background Sports nutrition science and practice • In theory, sports nutrition guidelines intend to support health and improve performance by adjusting energy and nutrient intake to sport-specific demands. • In practice, athletes often fail to align dietary intake to sport-specific guidelines, resulting in suboptimal energy and nutrient intake jeo...

INTRODUCTION: Accessible and effective treatment options are needed to manage obesity and its comorbidities. Commercial weight loss (WL) programs are a potential solution to the lack of available treatment, providing greater access at a lower cost than clinic-based approaches. However, few commercial programs have been rigorously evaluated. We asse...

INTRODUCTION: Acute fasted morning exercise may help create a greater negative 24-hour energy balance than the same exercise performed after a meal. However, research exploring fasted evening exercise is limited. We aimed to assess the effects of a 6-hour fast before evening exercise on post-exercise energy intake (EI). METHODS: In this crossover...

Introduction: Competitive amateur triathletes implement high training volumes, putting themselves at increased risk for low energy availability (LEA). Appropriate carbohydrate fueling before, during, and after exercise may help reduce athletes’ risk of LEA and improve training quality and adaptations. The goal of the present study was to assess ass...

Introduction: Nutritional knowledge has been shown to be one factor influencing nutritional status and diet-related decisions among athletes. Assessing knowledge status allows the identification of knowledge gaps, which can subsequently be addressed during nutritional counseling. This study aimed to assess sports nutrition knowledge of athletes aff...

Relative Energy Deficiency in Sport (REDs) is common among female and male athletes representing various sports at different performance levels, and the underlying cause is problematic low energy availability (LEA). It is essential to prevent problematic LEA to decrease the risk of serious health and performance consequences. This narrative review...

INTRODUCTION: Growing scientific evidence indicates that sphingolipids predict cardiometabolic risk, independently of and beyond traditional biomarkers such as low-density lipoprotein cholesterol. To date, it remains largely unknown if and how exercise, a simple, low-cost, and patient-empowering modality to optimise cardiometabolic health, influenc...

The Constrained Model of Total Energy Expenditure predicts that increased physical activity may not influence total energy expenditure, but instead, induces compensatory energetic savings in other processes. Much remains unknown, however, about concepts of energy expenditure, constraint and compensation in different populations, and it is unclear w...

When less energy is available to consume, people often lose weight, which reduces their overall metabolic rate. Their cellular metabolic rate may also decrease (metabolic adaptation), possibly reflected in physiological and/or endocrinological changes. Reduced energy availability can result from calorie restriction or increased activity energy expe...

INTRODUCTION: Exercise modulates hunger, food choices, and energy intake both acutely and chronically. However, these effects are highly variable and are affected by both individual characteristics and exercise-dependent factors (i.e., intensity, duration). It is unknown if the effects on hunger, food choices, and energy intake differ by type of ae...

INTRODUCTION: Growing scientific evidence indicates that sphingolipids predict cardiometabolic risk, independently of and beyond traditional biomarkers such as low-density lipoprotein cholesterol. To date, it remains largely unknown if and how exercise, a simple, low-cost, and patient-empowering modality to optimise cardiometabolic health, influenc...

INTRODUCTION: Energy intake (EI) following exercise is highly individual, resulting in compensatory eating in some individuals. Cycling and running differ in their requirements, so a one-by-one transformation is uncertain. The purpose of the study was to assess the impact of different types of aerobic exercise on post-exercise EI and compensatory E...

Background: An elevated core temperature (Tcore) increases the risk of performance impairments and heat-related illness. Internal cooling (IC) has the potential to lower Tcore when exercising in the heat. The aim of the review was to systematically analyze the effects of IC on performance, physiological, and perceptional parameters. Methods: A syst...

OBJECTIVE: Exercise in the fasted state (overnight fast) shifts fuel utilization towards increased fat oxidation. However, the effects on weight loss are equivocal. While breakfast omission may help reduce 24 h energy intake, we and others have shown that hunger is increased and (partial) compensation of the omitted breakfast occurs at subsequent m...

Energy intake in the post-exercise state is highly variable and compensatory eating - i.e., (over-) compensation of the expended energy via increased post-exercise energy intake - occurs in some individuals but not others. We aimed to identify predictors of post-exercise energy intake and compensation. In a randomized crossover design, 57 healthy p...

Female endurance athletes are considered a high-risk group for developing Relative Energy Deficiency in Sport (REDs). Due to the lack of educational and behavioral intervention studies, targeting and evaluating the effects of the practical daily management of REDs, we developed the Food and nUtrition for Endurance athletes—a Learning (FUEL) program...

Relative energy deficiency in sports (RED-S) is centered by chronic low energy availability (LEA), with a bidirectional causative relationship with mental health. Aside the well-established link between eating disorders and LEA, exercise addiction (ExA) has been proposed as another independent LEA risk factor. The aim of this investigation was to a...

The prevalence of obesity is increasing worldwide, and excess body weight is associated with a substantially increased risk of adverse health conditions. Exercise supports the prevention and management of obesity; however, when used for weight loss, exercise (even at high volumes) is usually relatively ineffective, frequently producing less weight...

Oslo, Norway

The competitive season in long-distance triathlon is characterized by increases in training load and volume from off- to peak-season, when athletes enter their primary competition. When athletes fail to meet the increased energy demand through the diet, either unintentionally or in attempts to improve their performance by means of weight loss, they...

INTRODUCTION: Exercise is recommended for weight management, yet weight loss from exercise is often less than expected based on measured energy expenditure. This is primarily due to compensatory energy intake, which occurs in most exercisers and overrides the appetite-suppressing effects of acute exercise. Exercising in a fasted state seems to be a...

Sevilla, Spain

Objectives The energy intake response to exercise is highly variable and energy (over-) compensation via increased post-exercise energy intake occurs in some individuals but not others. In explorative analyses, we aimed to identify biological and behavioral predictors of post-exercise ad libitum energy intake and whether these predictors differ fro...

Objective To characterize the contributions of the loss of energy-expending tissues and metabolic adaptations to the reduction in resting metabolic rate (RMR) following weight loss. Methods A secondary analysis was conducted on data from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy study. Changes in RMR, body comp...

Purpose: Wheelchair athletes experience a reduction in fat-free mass due to the underlying condition and/or muscle disuse. This leads to a lower resting energy expenditure (REE), as well as a lower energy expenditure during exercise or daily activities. Traditional markers of low energy availability (LEA), including amenorrhea and low bone mineral...

Relative energy deficiency in sport (RED-S) is a complex syndrome describing health and performance consequences of low energy availability (LEA) and is common among female endurance athletes. Various underlying causes of LEA have been reported, including disordered eating behavior (DE), but studies investigating the association with exercise addic...

Purpose: Elite rowers have large body dimensions, a high metabolic capacity, and they realize high training loads. These factors suggest a high total energy requirement (TER), due to high exercise energy expenditure (EEE) and additional energetic needs. We aimed to study EEE and intensity related substrate utilization (SU) of elite rowers during ro...

OBJECTIVE: Energy intake in response to exercise is highly variable. While some individuals show reduced energy intake post-exercise, allowing for an exercise-induced energy deficit, others show increased energy intake, (over-) compensating the expended energy. In an exploratory analysis, we aimed to identify biological and behavioral predictors of...

Hintergrund: Die Wettkampfvorbereitung auf einen Langdistanztriathlon (typischerweise 3,8/180/42,2 km Schwimmen/ Radfahren/Laufen) geht mit erhöhten Trainingsvolumen einher. Der dadurch erhöhte Energieverbrauch kann das Risiko eines relativen Energiemangels (Relative Energy Deficiency in Sports, RED-S) begünstigen. Ziel dieser Untersuchung war, das...

Energy intake in the post-exercise state is highly variable and compensatory eating – i.e., (over‑) compensation of the expended energy via increased post-exercise energy intake – occurs in some individuals but not others. We aimed to identify predictors of post-exercise energy intake and compensation. In a randomized crossover design, 57 healthy p...

Purpose Increased nitrogen losses observed during periods of energy deficiency are attributed to increased breakdown of endogenous proteins. Stable nitrogen isotope ratios (δ¹⁵N) measured in human hair have previously been shown to reflect prolonged periods of increased protein breakdown. The goal of this study was to determine whether stable nitro...

Energy is a finite resource that is competitively distributed among the body’s systems and biological processes. During times of scarcity, energetic “trade-offs” may arise if less energy is available than is required to optimally sustain all systems. More immediately essential functions are predicted to be prioritized, even if this necessitates the...

Background: The effect of physical activity and exercise on hunger and satiety has been well-studied in younger adults, but the influence of aging is less understood. While some evidence suggests that acute bouts of exercise induce a compensatory eating drive, long-term activity may improve satiety sensitivity. The objective of this study was to in...

Sirtuins are nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases that regulate numerous pathways such as mitochondrial energy metabolism in the human body. Lower levels of these enzymes were linked to diseases such as diabetes mellitus and were also described as a result of aging. Sirtuins were previously shown to be under the control o...

Short‐term energy deficits impair anabolic hormones and muscle protein synthesis. However, the effects of prolonged energy deficits on resistance training (RT) outcomes remain unexplored. Thus, we conducted a systematic review of PubMed and SportDiscus for randomized controlled trials performing RT in an energy deficit (RT+ED) for ≥3 weeks. We firs...

Objective To characterize the contributions of the loss of energy-expending tissues and metabolic adaptations to the reduction in resting metabolic rate (RMR) following weight loss. Methods A secondary analysis was conducted on data from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy study. Changes in RMR, body compo...

Energy availability describes the amount of dietary energy remaining for physiological functionality after the energy cost of exercise is deducted. The physiological and hormonal consequences of low energy availability (LEA) are well established, but the impact of LEA on physical activity behavior outside of exercise and, specifically, nonexercise...

Suppression of insulin-like growth factor 1 (IGF-1) and leptin secondary to low energy availability (LEA) may contribute to adverse effects on bone health. Whether a high-protein diet attenuates these effects has not been tested. Seven men completed three five-day conditions operationally defined as LEA (15 kcal kg fat-free mass (FFM)-1 day-1) with...

Although exercise modulates appetite regulation and food intake, it remains poorly understood how exercise impacts decision-making about food. The purpose of the present study was to assess the impact of an acute exercise bout on hypothetical choices related to the amount and timing of food intake. Forty-one healthy participants (22.0 ± 2.6 years;...

Energy availability (EA) is defined as the amount of dietary energy available to sustain physiological function after subtracting the energetic cost of exercise. Insufficient EA due to increased exercise, reduced energy intake, or a combination of both, is a potent disruptor of the endocrine milieu. As such, EA is conceived as a key etiological fac...

Although exercise modulates appetite regulation and food intake, it remains poorly understood how exercise impacts decision making about food. The purpose of the present study was to assess the impact of an acute exercise bout on hypothetical choices related to the amount and timing of food intake. Forty-one healthy participants (22.0 ± 2.6 years;...

PurposeWeight loss can result in the loss of muscle mass and bone mineral density. Resistance exercise is commonly prescribed to attenuate these effects. However, the anabolic endocrine response to resistance exercise during caloric restriction has not been characterized.Methods Participants underwent 3-day conditions of caloric restriction (15 kca...

Exercise is commonly utilized for weight loss, yet research has focused less on specific modifications to adipose tissue metabolism. White adipose tissue (WAT) is the storage form of fat, whereas brown adipose tissue (BAT) is a thermogenic tissue whose uncoupling increases energy expenditure. The most established BAT activator is cold exposure, whi...

Objectives Iron depletion is common around the world and among certain risk groups in developed countries. The overall purpose was to test the suitability of a novel plasma collection card for minimally invasive iron status assessment. Methods Twenty participants (10 f/10 m) participated in this cross‐sectional study. Ferritin and hemoglobin were...

Background Extensive research has established a clear positive relationship between physical activity (PA), even in small amounts, and psychological well-being, including benefits for emotional and mental health (e.g., decreased depression). However, little research has examined the relationship between PA and decision-making within emotionally amb...

UNSTRUCTURED Introduction: Our goal was to assess the validity of monitoring heart rate (HR) and energy expenditure (EE) while sitting or light-to-vigorous physical activity with four popular wrist worn wearables (Apple Watch Series 4, Polar Vantage V, Garmin Fenix 5, Fitbit Versa). Methods: 25 individuals performed 5-min of sitting, walking and ru...

Background: Physical activity reduces the incidences of noncommunicable diseases, obesity, and mortality, but an inactive lifestyle is becoming increasingly common. Innovative approaches to monitor and promote physical activity are warranted. While individual monitoring of physical activity aids in the design of effective interventions to enhance...

Background: The purpose of this study was to examine relationships among biomarkers of iron status, athletic performance, growth and development, and dietary intakes in pre-adolescent and adolescent male and female athletes. Methods: Two-hundred and forty-nine male (n = 179) (mean ± standard deviation for age = 12.0 ± 2.1 years, height = 156.3 ±...

Link to full text: https://www.mdpi.com/books/pdfview/book/1430

Objective: Given the number of college students with a normal BMI decreases 9-12% throughout the college experience, we wanted to model the traits responsible for behaviors impacting body composition in college-age women. Participants: Participants (n = 141) were recruited from a freshman-level nutrition course between August 2016 and May 2018. Me...

Objective: The purpose of this study was to determine the prevalence of poor iron status in young athletes throughout the stages of iron deficiency and assess sex differences with iron deficiency in relation to growth and development and dietary intake. Methods: A cross-sectional analysis evaluated young male and female athletes (n = 91) between th...

The purpose of this study was to examine the effects of an online sports nutrition curriculum on athletic performance and iron status in high school-aged male and female athletes. A repeated-measures design evaluated forty-three males (n=18) and females (n=25). Athletic performance and biomarkers of iron status were measured before and after partic...

It is well established that healthy nutrition and physical activity (PA) are key lifestyle factors that modulate lifelong health through their ability to improve body composition, musculoskeletal health, and physical and cognitive performance, as well as to prevent metabolic diseases including obesity, diabetes mellitus, and cardiovascular disease...

Objectives: Laboratory experiments suggest that exercise can modulate appetite regulation and ad libitum food intake, but the impact of exercise on decision making about food remains poorly understood. As such, this study sought to assess the impact of an acute exercise bout on food choices, in particular, the amount and taste preference for immed...

Objectives Weight loss, especially when achieved by caloric restriction (CR), reduces total daily energy expenditure (EE), which can attenuate further weight loss. Although exercise is a common countermeasure to the decline in EE, it is unknown whether prescribed exercise leads to compensatory changes in moderate-to-vigorous physical activities (MV...

A curvilinear relationship exists between physical activity (PA)and dietary energy intake (EI), which is reduced in moderately active when compared to inactive and highly active individuals, but the impact of PA on eating patterns remains poorly understood. Our goal was to establish the relationship between PA and intake of foods with varying energ...

Caloric‐restriction is necessary for efficacious weight loss, but can lead to unwanted losses of lean mass and bone mineral content. High‐protein diets have been shown to protect lean mass during caloric‐restriction and may have similarly preservative effects on bone either through attenuating increases in bone resorption or elevating bone formatio...

In the United States, 2 out of 3 adults are overweight or obese. To lose weight, individuals engage in a variety of dietary and exercise interventions. Despite successful weight loss initially, weight loss is typically less than expected and most individuals regain weight. Both phenomena have been linked to a reduction in resting metabolic rate (RM...

Acute exercise can induce either a compensatory increase in food intake or a reduction in food intake, which results from appetite suppression in the post-exercise state. The timing of food choice—choosing for immediate or later consumption—has been found to influence the healthfulness of foods consumed. To examine both of these effects, we tested...

Exercise suppresses appetite and reduces calorie intake over the short‐term, but the long‐term consequences of exercise on food intake, and in particular those on food choices, remain unclear. Previous research suggests that people who are moderately active tend to consume fewer calories than those who are inactive, but very high activity levels ar...

Brown/beige fat plays a crucial role in maintaining energy homeostasis through non-shivering thermogenesis in response to cold temperature and excess nutrition (adaptive thermogenesis). Although numerous molecular and genetic regulators have been identified, relatively little information is available regarding thermogenic dietary molecules. Recentl...

In order to monitor their energy requirements, athletes may desire to assess energy expenditure (EE) during training and competition. Recent technological advances and increased customer interest have created a market for wearable devices that measure physiological variables and bodily movement over prolonged time periods and convert this informati...

Efficacious weight loss which reduces risk of mortality requires both significant initial weight loss and prevention of weight regain. Performing either aerobic or resistance exercise and elevating protein intake during caloric restriction (CR) preserves—and may increase—lean mass (LM), leading to targeted loss of fat mass. To maximize the...

Background: The first 2 years of a child's life are a particularly critical time period for obesity prevention. Aim: An increasing amount of research across the world is aimed at understanding factors that impact early childhood obesity and developing interventions that target these factors effectively. With this growing interest, new and interd...

Rationale: Natural stable nitrogen isotope ratios (δ(15) N values) are frequently used for the determination of provenance and dietary assessment of recent and ancient humans. Although individual δ(15) N values typically correspond to the dietary δ(15) N composition, they are also affected by metabolic conditions. Preferred matrices for the mesure...

Brown adipose tissue (BAT) is a specialized fat tissue that has a high capacity to dissociate cellular respiration from ATP utilization, resulting in the release of stored energy as heat. Adult humans possess a substantial amount of BAT in the form of constitutively active brown fat or inducible beige fat. BAT activity in humans is inversely correl...

Little is known about whether athletes follow hydration guidelines. The objective of the present study was to assess fluid status in female soccer players in a hot and humid environment, and to assess the effect of an intervention aimed at preventing players from exercising in a dehydrated state. We hypothesized that following the intervention, pla...

Natural stable isotope ratios (δ(15)N) of humans can be used for nutritional analyses and dietary reconstruction of modern and historic individuals and populations. Information about an individual's metabolic state can be obtained by comparison of tissue and dietary δ(15)N. Different methods have been used to estimate dietary δ(15)N in the past; ho...

Ultra-endurance athletes often accumulate an energy deficit when engaging in ultra-endurance exercise, and upon completion of the exercise, they exhibit endocrine changes that are reminiscent of starvation. However, it remains unclear whether these endocrine changes are a result of the exercise per se or secondary to the energy deficit, and more im...