Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Energy Budgets00:51

Energy Budgets

9.3K
Organisms must balance energy intake with the energy required for growth, maintenance and reproduction. These trade-offs result in a variety of survivorship and reproductive strategies, including semelparity and iteroparity. Semelparous species, like annual plants, have only one reproductive episode in their lifetimes and consequently have short lifespans. Iteroparous species, by contrast, have many reproductive events during their lifetimes but have relatively few offspring. These two...
9.3K
Energy Balance01:19

Energy Balance

446
The human body gets energy from the three macronutrients: carbohydrates, proteins, and fats. Energy is released when the chemical bonds in the organic compounds present in the food are broken down. The energy content of food is measured in kilocalories (kcal), defined as the amount of heat required to raise the temperature of one kilogram of water by one degree Celsius. This value is determined by measuring the temperature change of the water surrounding a calorimeter after the complete...
446
Metabolic Rate01:25

Metabolic Rate

412
The human body is a powerhouse of energy, with every cell performing numerous functions that require energy. This energy production and consumption is measured by the metabolic rate, which quantifies the total heat generated by all the body's chemical reactions and mechanical work. This measurement helps to determine the rate of kilocalorie (kcal) consumption needed to fuel all ongoing activities.
The Basal Metabolic Rate (BMR) measures the energy expended at rest.
Several factors influence...
412
Metabolic States of the Body: Fasting and Starvation01:24

Metabolic States of the Body: Fasting and Starvation

1.5K
During the initial hours of fasting, the body uses up its glycogen stores as an energy source. Once these glycogen reserves are depleted, the body begins breaking down stored triglycerides and structural proteins. During this stage, glycerol becomes a key substrate for gluconeogenesis, while free fatty acids undergo beta-oxidation to provide energy for tissues, such as skeletal muscle. In the fasting state, the body spares protein breakdown as much as possible to conserve muscle and structural...
1.5K
Production Efficiency01:01

Production Efficiency

16.9K
Net production efficiency (NPE) is the efficiency at which organisms assimilate energy into biomass for the next trophic level. Due to low metabolic rates and less energy spent on thermoregulatory processes, the NPE of ectotherms (cold-blooded animals) is 10 times higher than endotherms (warm-blooded animals).
16.9K
Metabolic States of the Body: The Postabsorptive State01:18

Metabolic States of the Body: The Postabsorptive State

360
The postabsorptive state usually starts about four hours after a meal and lasts until the next meal is eaten. During this time, the digestive system stops absorbing nutrients, and the body uses stored energy reserves to maintain stable blood glucose levels.
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...
360

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Increased Vulnerability to Dehydration Due to Heat Stress and Drought Across Reproductive States for Pastoralist Women in Northern Kenya.

American journal of human biology : the official journal of the Human Biology Council·2026
Same author

The 9+ month marathon: How pregnancy may have shaped human endurance capacities.

Anatomical record (Hoboken, N.J. : 2007)·2026
Same author

Real-time heart rate in the wild: remote collection of cardiac data in baboons using a low-power Bluetooth and LoRaWAN system.

bioRxiv : the preprint server for biology·2026
Same author

Using insertable cardiac monitors to test determinants of heart rate and activity in captive baboons.

bioRxiv : the preprint server for biology·2026
Same author

Reduced Fat Oxidation as a Potential Pathway Linking Early-Life Adversity to Obesity Risk: Evidence From Vanuatu.

American journal of human biology : the official journal of the Human Biology Council·2026
Same author

Total Energy Expenditure and Physical Activity Profiles Among Reindeer Herders and Office Workers of Northern Finland.

American journal of human biology : the official journal of the Human Biology Council·2025
Same journal

Co-Ingestion of a Commercially Available Dandelion Root Powder Elicited No Additional Diuretic Effect Over 4 Hr Compared to Ingestion of Water Alone in Physically Active Young Adults.

International journal of sport nutrition and exercise metabolism·2026
Same journal

Nutrition for Elite Male Ice Hockey: Evidence-Based Recommendations.

International journal of sport nutrition and exercise metabolism·2026
Same journal

Beyond Belief? Absence of Double-Blinding and Limited Ecological Validity in Carbohydrate Loading Research.

International journal of sport nutrition and exercise metabolism·2026
Same journal

Quantifying and Comparing Training Load Metrics in Cycling: A Methodology Review.

International journal of sport nutrition and exercise metabolism·2026
Same journal

Investigating the Effects of a Novel Salmon-Derived Protein Peptide on Markers of Recovery From Exercise-Induced Muscle Damage.

International journal of sport nutrition and exercise metabolism·2026
Same journal

Response to Pethick et al.

International journal of sport nutrition and exercise metabolism·2026
See all related articles

Related Experiment Video

Updated: Jul 16, 2025

Determining Basal Energy Expenditure and the Capacity of Thermogenic Adipocytes to Expend Energy in Obese Mice
06:57

Determining Basal Energy Expenditure and the Capacity of Thermogenic Adipocytes to Expend Energy in Obese Mice

Published on: November 11, 2021

5.3K

Total Energy Expenditure and Nutritional Intake in Continuous Multiday Ultramarathon Events.

Andrew W Best1, Amanda McGrosky2, Zane Swanson2

  • 1Department of Biology, Massachusetts College of Liberal Arts, North Adams, MA, USA.

International Journal of Sport Nutrition and Exercise Metabolism
|September 14, 2023
PubMed
Summary
This summary is machine-generated.

Ultraendurance athletes face extreme energy demands, with physical activity levels exceeding four times their basal metabolic rate during multiday races. Athletes meet over half their energy needs through body stores, highlighting the critical role of nutrient absorption in performance.

Keywords:
doubly labeled waterfunctional performancephysical activity level

More Related Videos

Determining the Contribution of the Energy Systems During Exercise
11:15

Determining the Contribution of the Energy Systems During Exercise

Published on: March 20, 2012

41.5K
Using a Combination of Indirect Calorimetry, Infrared Thermography, and Blood Glucose Levels to Measure Brown Adipose Tissue Thermogenesis in Humans
04:54

Using a Combination of Indirect Calorimetry, Infrared Thermography, and Blood Glucose Levels to Measure Brown Adipose Tissue Thermogenesis in Humans

Published on: June 2, 2023

1.4K

Related Experiment Videos

Last Updated: Jul 16, 2025

Determining Basal Energy Expenditure and the Capacity of Thermogenic Adipocytes to Expend Energy in Obese Mice
06:57

Determining Basal Energy Expenditure and the Capacity of Thermogenic Adipocytes to Expend Energy in Obese Mice

Published on: November 11, 2021

5.3K
Determining the Contribution of the Energy Systems During Exercise
11:15

Determining the Contribution of the Energy Systems During Exercise

Published on: March 20, 2012

41.5K
Using a Combination of Indirect Calorimetry, Infrared Thermography, and Blood Glucose Levels to Measure Brown Adipose Tissue Thermogenesis in Humans
04:54

Using a Combination of Indirect Calorimetry, Infrared Thermography, and Blood Glucose Levels to Measure Brown Adipose Tissue Thermogenesis in Humans

Published on: June 2, 2023

1.4K

Area of Science:

  • Sports Science
  • Human Physiology
  • Nutritional Science

Background:

  • Continuous multiday ultramarathons present significant energetic and nutritional challenges.
  • Limited data exists on energy expenditure during these extreme endurance events.

Purpose of the Study:

  • To measure total energy expenditure (TEE) and physical activity level (PAL) in elite ultramarathon runners.
  • To investigate the relationship between event duration and PAL.
  • To analyze nutritional intake and energy balance during a multiday ultramarathon.

Main Methods:

  • Utilized doubly labeled water (DLW) to measure TEE in ultramarathon athletes.
  • Calculated PAL by dividing TEE by basal metabolic rate (BMR).
  • Collected nutritional intake data from race winners and analyzed body energy store utilization.

Main Results:

  • PAL exceeded four times BMR in both Cocodona 250 and Arizona Trail events.
  • A significant inverse relationship was found between event duration and PAL across ultraendurance events.
  • Race winner met ~53% of energy demand through diet (85.6% carbohydrate) and ~47% via catabolism of body stores.

Conclusions:

  • Continuous multiday ultramarathons incur substantial energetic deficits.
  • Macronutrient absorption and/or storage are critical determinants of ultramarathon performance.