Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT05773469 |
| Other study ID # |
595711 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
February 28, 2023 |
| Est. completion date |
November 26, 2023 |
Study information
| Verified date |
January 2024 |
| Source |
University of Exeter |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
This project is feasibility study looking at extreme exercise and possible diet intervention
study to counter muscle and weight loss during a 2 person Greenland Ski Traverse in April
2023. By increasing energy intake to above the currently theoretical capacity (2.5 x RMR) the
aim is to test a method to find out if there is a maximum to energy intake and whether energy
deficit can be minimised; weight loss attenuated, and whether muscle can be preserved. If
not, what are the likely adaptive mechanisms and use this to inform future work on dietary
interventions
Description:
Prolonged endurance events provide a unique opportunity to study the physiological limits of
human performance. When nutrition is adequate, maintaining weight is directly related to
energy expenditure. In extreme environments however, such as ocean rowing, the investigators
have shown that rowers lost 10% weight, had a high energy expenditure (5,000kcal/d or 3.1 x
basal metabolic rate) which was not met by energy intake (EI). Even in the presence of over
~5000kcal food per day, rowers chose to eat only ~3800kcal/d (2.4 x RMR) and lost weight,
rather than eat more. It is also rare, outside of elite performance, that EI is above 2.5 x
RMR and is suggestive of some sort of regulatory mechanism. Previous work has shown that high
energy expenditures (EE) are not sustainable over long periods and that EE decreases with
duration, plateauing at around 2.5 x RMR. This is in attempt to balance energy requirements
in order to minimise body mass loss and increase chances of survival. Using data from the
previous PhD study in ocean rowers (Holsgrove-West., 1st PhD study), and extrapolating data
from the studies used to model TEE and duration, and overfeeding studies, voluntary energy
intake calculated from body mass loss were consistently around 2.4 x RMR, suggesting a
possible numerical value to the limit of EI. This has not been measured experimentally. If
the theory of maximal EI is true, any intake above the maximum [2.4 x RMR] cannot be used for
energy and would be excreted. Any BM loss would therefore reflect difference between EE and
the maximal EI, not the actual EI. To investigate the EI limit therefore requires
simultaneous measurements of EE, EI and body mass changes whilst ensuring EI above the
theoretical maximum.In the presence of energy deficit and body mass loss, ocean rowers
demonstrated an adaptive response by selectively maintaining or losing muscle. Loaded muscles
were preserved whilst unloaded muscles atrophied. An obvious countermeasure could be to load
the muscles that wasted, but to what expense? With finite energy intake, and greater demand
from the muscle mass, other components of EE such as RMR, NEAT or exercise component may
compensate, or endure a greater body mass loss. This interaction warrants further
investigation. Logistically it is difficult to ask rowers to exercise mid-race, and
compliance would be unknown. An expedition that involves greater muscle involvement and high
EE is needed. Trekking across Greenland provides the high EE environment without the lower
limb disuse. In addition, due to logistical reasons of sample storage in ocean rowing, energy
expenditure and intake were collected only in the final week of the row, and energy balance
did not match with body mass loss. This would indicate a different energy deficit and
different energy expenditure or intake earlier on in the row. These initial acute changes are
unknown and possibly responsible for the large weight loss seen by the end of the row. This
project will attempt to fill that gap and measure these initial changes by measuring daily EI
and EE.EI is rarely measured alongside EE and body mass loss and instead inferred from EE.
This study aims to establish whether this maximal EI exists, by directly measuring both
components of energy balance and how the body compensates with changes in the components of
EE.
