Changes in physical activity levels and gait parameters after 60-days of 6°Head-Down-Tilt Bed Rest (HDT-BR) – a preliminary data analysis

Ines Ebner, Birte Coppers, Elie-Tino Godonou, Maren Dreiner, Simon Herger, Annegret Mündermann, G Schett, Anja Niehoff, Anna-Maria Liphardt

Publikation: Beitrag in Buch/Bericht/KonferenzbandKonferenzbeitrag - Abstract in KonferenzbandForschungBegutachtung


Introduction: Disuse leads to deconditioning of the human body. Physical activity and gait parameters are
important indicators of physical function and could serve as predictors of the rate of deterioration and
responsiveness to countermeasures. The aim of this study is to investigate accelerometer-based physical activity
and spatiotemporal gait parameters before, during and after 60 days of 6° head-downtilt bed rest (HDT) with
and without artificial gravity and exercise countermeasures.
Methods: The data were collected during the European Space Agency (ESA)-funded “Bed Rest with Artificial
gravity and Cycling Exercise (BRACE)” study, a randomized controlled trial with two campaigns (C1, C2) and
three interventions (60 days of 6° head-down-tilt bed rest (HDT), HDT+cycling, and HDT+articifical gravity
(AG)+cycling. HDT was preceded by 14 days of baseline data collection (BDC) and followed by 14 days of
recovery (R). This is the preliminary analysis of twelve healthy male participants (age 30.3 ± 5.9 years; body mass
index 23.3 ± 2.1 kg/m²) of C1. Physical activity (inactive (IN), light (LIG), moderate (MOD), and vigorous (VIG))1
was collected by wrist-worn (non-dominant) accelerometry (GENEActiv, Activinsights Ltd, Kimbolton, UK) before
C1 (preStudy (BDC-28 to BDC-14), during (HDT18 to HDT23) and after C1 (R+0 to R+13, R+14 to R+28) and
analyzed with R-package GGIR2. Spatiotemporal gait parameters walking speed, total number of steps (SteN),
cadence (Cd), stride time (StrT) and stride length (StrL) were collected on BDC-4, R+2 and R+29 with a seveninertial-sensors system (RehaGait Analyzer Pro, Hasomed, Magdeburg, Germany) during a 30-minute treadmill
walking protocol. Univariate and repeated measures ANOVAs were computed to detect changes in the physical
activity parameters and spatiotemporal gait parameters over time and by intervention with Bonferroni corrected
post-hoc tests.
Results: Time significantly affected IN (preStudy vs. HDT23: +26.8% ± 17.1; preStudy vs. R+28: - 4.5% ± 9.7;
F1.4,8.42=24.30; p=0.001), LIG (preStudy vs. HDT23: -53.8% ± 13.9; preStudy vs. R+28: +29.3% ± 33.6;
F1.51,9.05=27.12; p<0.001) and MOD (preStudy vs. HDT23: -69.3% ± 14.0; preStudy vs. R+28: +44.9% ± 54.7;
F4,24=15.66; p<0.001), but not VIG (preStudy vs. HDT23: -91.1% ± 11.9: preStudy vs. R+28: -19.8% ± 42.8;
p=0.132). There was no intervention effect on any physical activity parameter (group: all p-values> 0.336;
time*group: all p-values > 0.246). There were no time effect (all p-values > 0.083), and no time*group
interactions (all p-values > 0.387) on any gait parameters. Control group participants had slower walking speed
(HDT: 3.86 km/h ± 0.51; HDT+AG+cycling: 4.13 km/h ± 0.25; HDT+cycling: 4.08 km/h ± 0.10; F2,9=4.388;
p=0.047 and shorter StrL (HDT: 1.08 m ± 0.11; HDT+AG+cycling: 1.22 ± 0.06; HDT+cycling: 1.26 ± 0.05; F
2,9=5.995; p=0.022) at BDC compared with HDT+cycling and HDT+AG+cycling and the difference persisted at
all time points.
Conclusions: Physical activity levels did not differ between the groups, but as expected, time spent in moderate
and low activity changed over time and already between the preStudy and the ambulatory BDC period. Despite
attempts to maintain preStudy physical activity levels during BDC, an increase in time spent inactive is evident.
The intra-individual changes in physical activity from preStudy to HDT will allow to investigate the influence of
habitual physical activity routines, and intra-individual differences should be considered when interpreting results
on the response of the musculoskeletal system to immobilization. Walking speed and stride length during the
gait experiment were lower in the control condition compared to the interventions, with no change over time.
TitelChanges in physical activity levels and gait parameters after 60-days of 6°Head-Down-Tilt Bed Rest (HDT-BR) – a preliminary data analysis
PublikationsstatusVeröffentlicht - 2023
VeranstaltungHuman Physiology Workshop Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR) - DLR :envihab Forum 51147 Cologne Germany Planitzweg, Cologne, Deutschland
Dauer: 08.12.202308.12.2023


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