Physiological and psychological determinants of whole-body endurance exercise following short-term sustained operations with partial sleep deprivation
European Journal of Applied Physiology
https://doi.org/10.1007/s00421
Physiological and psychological determinants of whole-body endurance exercise following short-term sustained operations with partial sleep deprivation
Michail E. Keramidas 0 1 2
Magnus Gadefors 0 1 2
Lars‑Ove Nilsson 0 1 2
Ola Eiken 0 1 2
0 Military Academy Karlberg , Stockholm , Sweden
1 Department of Environmental Physiology, Swedish Aerospace Physiology Center, Royal Institute of Technology- KTH , Berzelius väg 13, 171 65 Solna , Sweden
2 Michail E. Keramidas
Purpose The study examined the effects of short-term field-based military training with partial sleep deprivation on wholebody endurance performance in well-trained individuals. Methods Before and after a 2-day sustained operations (SUSOPS), 14 cadets performed a 15-min constant-load cycling at 65% of peak power output (PPO; CLT65), followed by an exhaustive constant-load trial at 85% of PPO (CLT85). Physiological [oxygen uptake (V̇ O2), heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), and regional oxygenation (TOI) in the frontal cerebral cortex and vastus lateralis muscle] and psychological [effort perception (RPE), affective valence (FS), and perceived activation (FAS)] variables were monitored during exercise. Results SUSOPS reduced time to exhaustion in CLT85 by 29.1% (p = 0.01). During the CLT65 trial, SUSOPS potentiated the exercise-induced elevations in V̇ O2 and HR (p < 0.05), and blunted MAP (p = 0.001). CO did not differ between trials. Yet, towards the end of both CLT85 trials, CO tended to decline (p ≤ 0.08); a response that occurred at an earlier stage in the SUSOPS trial. During CLT65, SUSOPS altered neither cerebral nor muscle TOI. The SUSOPS CLT85 trial, however, was terminated at similar leg-muscle deoxygenation (p > 0.05) and lower prefrontal cortex deoxygenation (p < 0.01). SUSOPS increased RPE at submaximal intensities (p = 0.05), and suppressed FAS and FS throughout (p < 0.01). Conclusions The present findings indicate, therefore, that a brief period of military sustained operations with partial sleep deprivation augment cardiorespiratory and psychological strain, limiting high-intensity endurance capacity.
Autonomic dysfunction; Cerebral oxygenation; Effort; Fatigue; Motivation; Muscle oxygenation
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Abbreviations
CI Confidence interval
CLT65 A 15-min constant-load trial at 65% of peak
power output
CLT85 Exhaustive constant-load trial at 85% of peak
power output
CO Cardiac output
CON Control trial
DAP Diastolic arterial pressure
FAS Perceived activation
Communicated by Phillip D Chilibeck.
fR
FS
HR
[La]
MAP
MFI
NIRS
PETCO2
POMS-SF
PPO
RER
RPE
SAP
SD
SUSOPS
SV
TOI
V̇ E
V̇ E/V̇ CO2
V̇ E/O2
V̇ CO2
̇
V̇ O2
VO2peak
VT
Δ[HbO2]
Δ[HbO2]
Introduction
Ventilatory equivalent for oxygen
Carbon dioxide production
Oxygen uptake
Peak oxygen uptake
Tidal volume
Changes in oxyhaemoglobin
Changes in deoxyhaemoglobin
Military and emergency-response personnel are often
required to perform sustained and demanding work in
environmental extremes, while provisions for full recovery are
limited. During such multi-day tasks, individuals may be
exposed to several behavioural stressors, including physical
and mental exertion, partial or total sleep deprivation, and
caloric deficit (i.e., energy intake is lower than expenditure),
which, independently or interactively, might result in
functional impairments
(for reviews, see Henning et al. 2011;
Vrijkotte et al. 2016; Montain and Young 2003)
.
Specifically, military-based studies have suggested that a prolonged
period of sustained operations (SUSOPS) degrades
cognitive and physical performance; thus, aerobic work capacity
is typically suppressed
(Guezennec et al. 1994; Nindl et al.
2002)
. Physiological and psychological modifications, such
as low energy substrate availability
(Smith et al. 2016;
Rognum et al. 1981)
, muscle-mass loss
(Johnson et al. 1994)
,
hypovolemia and/or hypohydration
(Lieberman et al. 2005;
Wittels et al. 1996)
, functional peripheral deteriorations
(e.g., impaired mitochondrial efficiency; Fernstrom et al.
2007)
, and decreased motivation and enhanced effort
perception
(Lucas et al. 2009; Lieberman et al. 2005, 2006)
,
have been regarded as potential determinants of physical
performance in such multi-stressor conditions.
The SUSOPS effect on endurance capacity seems to be
dictated primarily by the severity of energy and sleep
deprivation encountered. For instance, short-term (≤ 10 days)
periods of low-to-moderate hypocaloria cause minimal, if at
all, change in aerobic capacity
(Dohm et al. 1986; Knapik
et al. 1987; Guezennec et al. 1994)
.
Friedl (1995)
has argued
that body mass losses of at least 5–10% might be required
to adversely affect performance. Moreover, although it is
well established that partial sleep deprivation deteriorates
cognitive and mental performance, its impact on endurance
capacity is equivocal; a few studies have observed an
impairment, while (...truncated)