Effect of 14 Day Bed Rest on Health Outcomes in Young and Older Participants
Condition: Muscular Atrophy
MeSH terms: Muscular Atrophy
Study type: Interventional

Summary: 
      This investigation aimed to compare the response of older adult and young men to 14 day
      bed-rest and subsequent 28 day rehabilitation. Sixteen older (OM: 55-65 years) and seven
      young men (YM: 18-30 years) were exposed to 14-day bed rest (BR) followed by 14-day
      rehabilitation (R), and 400-day of R. Quadriceps muscle volume, force and explosive power of
      leg extensors, single fiber isometric force, peak aerobic power, gait stride length, and
      several metabolic were measured before and after BR and after R.
    

Detailed description: 
      Twenty-three healthy men, of which 7 young (YM; aged 18-30 years) and 16 older adults (OM;
      aged 55-65 years) were recruited for the study. All participants underwent medical
      examination and routine blood and urine analysis. Exclusion criteria were: smoking; regular
      alcohol consumption; ferromagnetic implants; history of deep vein thrombosis with D-dimer >
      500 μg·L-1; acute or chronic skeletal, neuromuscular, metabolic and cardiovascular disease
      conditions; pulmonary embolism. Participants were informed of the purpose, procedures and
      potential risk of the study before signing the informed consent. The study was performed in
      accordance with the ethical standards of the 1964 Declaration of Helsinki and was approved by
      the National Ethical Committee of the Slovenian Ministry of Health on April 17, 2012.

      The study was conducted in controlled medical environment of the Orthopedic Hospital of
      Valdoltra, Slovenia. The participants were housed in standard air conditioned hospital rooms
      and were under constant surveillance with 24-hour medical care. For 14 days, the participants
      performed all daily activities in bed and received eucaloric controlled meals three times a
      day. Dietary energy requirements were designed for each subject multiplying resting energy
      expenditure by factors 1.2 and 1.4 in BR and ambulatory period, respectively. The resting
      energy expenditure was calculated as done in previous studies. The macronutrient food content
      set at 60% of carbohydrates, 25% fat, and 15% of proteins, according to the scheme of the so
      called "mediterranean diet" and adopted also in previous bed rest protocols. Energy balance
      was checked weekly by fat mass assessment. The daily protein intake was 1.1-1.25 g kg-1 in
      both groups, in BR and recovery period respectively, except the subgroups of OM who received
      a supplementation (see below).

      After the BR, participants underwent a rehabilitation protocol (R) that consisted of 4-week
      supervised multimodal exercise program with 3 sessions per week. In each session,
      participants performed 12-minute warm-up, 15-20 minutes of balance and strength training, and
      20-30 minutes of endurance training.
    

Intervention name(s): physical inactivity or bed rest with supervised recovery
Intervention type(s): Behavioral
Intervention description(s): All (older and younger) participants underwent 14 day of horizontal bed rest with all 24 hour daily activities were performed lying in a bed. Maximal one pillow was allowed. 28-day supervised recovery was performed 3 times weekly for 75 minutes/session.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Ageing; Physical inactivity; Functional decline; Reconditioning