Randomized cross-over design with 10 male subjects and 3 campaigns to test whether the negative effects of bed rest (6º head-down tilt) on the various systems of the body and the consequences to health of simulated weightlessness can be counteracted by the use of a defined training programme.
The SAG study was a single center, open-label crossover trial with healthy men conducted in three campaigns at the Institute of Aerospace Medicine, Cologne, Germany. The subjects were quasi randomized alternatively by enrolment to undertake the different training interventions or to be in the control group during 5 days of immobilisation in 6° head down tilt position. The subjects were quasi randomized either to the one of the training programs or the non-training group depending on the arrival at the Institute of Aerospace Medicine. The study started November 01st, 2010 and was finished May 29th, 2011. The first campaign lasted from November 01st to November 21sh, 2010, the second campaign from January 10th to January 30th, 2011 and the third campaign from May 09th to May 29th, 2011. Each campaign comprised a 5 day adaptation-, a 5 day intervention phase in HDT bed rest, and a 5 day recovery phase (15 days in total) in-house at the Metabolic Ward of the Institute of Aerospace Medicine. Baseline Data were collected during the adaptation phase (BDC Baseline Data Collection) when subjects could move free inside the lab. The intervention was administered during the bed rest phase where the subjects had to lie in bed in 6° head down tilt (HDT Head Down Tilt) position and were not allowed to get up. Recumbency was to be adhered to at all times including all activities (hygienic procedures, leisure activities). The bed rest phase was followed by a recovery phase (R+).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
10
A Smith Machine with fixed rails was used to guide the heel raise and squat exercises in the vertical axis. A metronome was used to direct the subjects during the performance of the exercises. Squats and heel raises were performed against body weight plus the additional weight of the barbell (15 kg). The heel raises were performed with straight knees and without ankle dorsiflexion. The shallow squats were performed continuously for 3 minutes. The hopping and the cross-hopping exercises were performed without Smith Machine. The bilateral hops were performed at \~ 3 repetitions per second with 15-s rest insertions between each set. Cross-hopping was performed continuously for 3 minutes against \~ 1.3 repetitions per second. Except for the duration of the static squat, with progressed from 45 s at HDT1 to 70 s at HDT5, none of the exercises were progressed during the study. Including the scheduled rest pauses, the LRT sessions were completed in 24 minutes.
German Aerospace Center (DLR)
Cologne, Germany
Maximal knee extensor and plantar flexor muscle force
The maximal voluntary isometric force (MVC) was assessed before and following bed rest. MVC measurements were obtained from the left leg using the Biodex 3 system (Biodex Medical Systems, Shirley, New York, USA).
Time frame: Baseline, after 5 days of bed rest
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