Variable Energy Availability Exposure and Heterogeneous Physiological Responses to a Prescribed Low Energy Availability Intervention in Free-Living Male Endurance Athletes: A Pilot Case-Series.
- 1School of Allied Health, Curtin University, Bentley, WA 6102, Australia.
- 2School of Population Health, Curtin University, Bentley, WA 6102, Australia.
Abstract
Low energy availability (LEA) is commonly studied under tightly controlled laboratory conditions. However, its induction and monitoring in free-living athletes remain poorly understood, partly due to challenges in measuring energy intake (EI), exercise energy expenditure (EEE) and daily behavioural variability. This study examined whether a prescribed LEA intervention leads to a consistent energy deficit and described the variability in energy availability (EA) and associated physiological and performance responses. In this pilot case series with a repeated-measures control-intervention structure, trained male endurance athletes (n = 3) completed a 14-day intervention targeting LEA (~20 kcal (~84 kJ)·kg fat-free mass (FFM)⁻¹·day⁻¹) by increasing EEE while maintaining habitual EI. EA was estimated daily using image-based dietary assessment, heart rate-derived EEE and dual-energy X-ray absorptiometry-derived FFM; resting metabolic rate (RMR), performance and well-being were assessed pre- and post-intervention. Despite the target, achieved EA varied substantially within and between participants (day-to-day SD 7-20 kcal·kg FFM⁻¹·day⁻¹), reflecting the magnitude and distribution of EEE rather than a uniform deficiency. Responses were heterogeneous: RMR showed no consistent direction, haemoglobin decreased modestly in all athletes, body-composition changes were small, and performance ranged from decline to improvement. Mean EA interpreted in isolation may obscure intra-individual variability, indicating a need for methods that capture it in free-living research.
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BibTeX
@article{forchino2026variable,
title = {{Variable Energy Availability Exposure and Heterogeneous Physiological Responses to a Prescribed Low Energy Availability Intervention in Free-Living Male Endurance Athletes: A Pilot Case-Series.}},
author = {Fabricio Forchino and Carly J Brade and Deborah A Kerr and Dale W Chapman},
journal = {Sports (Basel, Switzerland)},
year = {2026},
month = oct,
doi = {10.3390/sports14100446},
url = {https://europepmc.org/article/MED/42931583},
note = {CC BY},
}
RIS
TY - JOUR
TI - Variable Energy Availability Exposure and Heterogeneous Physiological Responses to a Prescribed Low Energy Availability Intervention in Free-Living Male Endurance Athletes: A Pilot Case-Series.
AU - Fabricio Forchino
AU - Carly J Brade
AU - Deborah A Kerr
AU - Dale W Chapman
PY - 2026
DA - 2026/10/09
JO - Sports (Basel, Switzerland)
DO - 10.3390/sports14100446
UR - https://europepmc.org/article/MED/42931583
AB - Low energy availability (LEA) is commonly studied under tightly controlled laboratory conditions. However, its induction and monitoring in free-living athletes remain poorly understood, partly due to challenges in measuring energy intake (EI), exercise energy expenditure (EEE) and daily behavioural variability. This study examined whether a prescribed LEA intervention leads to a consistent energy deficit and described the variability in energy availability (EA) and associated physiological and performance responses. In this pilot case series with a repeated-measures control-intervention structure, trained male endurance athletes (n = 3) completed a 14-day intervention targeting LEA (~20 kcal (~84 kJ)·kg fat-free mass (FFM)⁻¹·day⁻¹) by increasing EEE while maintaining habitual EI. EA was estimated daily using image-based dietary assessment, heart rate-derived EEE and dual-energy X-ray absorptiometry-derived FFM; resting metabolic rate (RMR), performance and well-being were assessed pre- and post-intervention. Despite the target, achieved EA varied substantially within and between participants (day-to-day SD 7-20 kcal·kg FFM⁻¹·day⁻¹), reflecting the magnitude and distribution of EEE rather than a uniform deficiency. Responses were heterogeneous: RMR showed no consistent direction, haemoglobin decreased modestly in all athletes, body-composition changes were small, and performance ranged from decline to improvement. Mean EA interpreted in isolation may obscure intra-individual variability, indicating a need for methods that capture it in free-living research.
SN - 2075-4663
ER -