Effect of 14 Day Bed Rest on Health Outcomes in Young and Older Participants

Study Overview
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Brief Summary
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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
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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.

Official Title
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CB147 - Physical Activity and Nutrition for Quality Ageing

Conditions
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Muscular Atrophy

Intervention / Treatment
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* Behavioral: physical inactivity or bed rest with supervised recovery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Body mass index < 28 kg/m2 Short physical performance battery score >= 9 Exclusion Criteria: 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.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Old group<br>16 old participants (55-65 years) were included in physical inactivity or bed rest with supervised recovery intervent and underwent 14-day of bed rest. Bed rest was followed by 28-day recovery. During the bed rest participants will remain 24-hour horizontal with all daily activities performed lying in a bed. No social isolation will be forced. During the recovery participants will 3-times weekly per 75 minutes perform guided exercises to achieve baseline level. | Behavioral: physical inactivity or bed rest with supervised recovery<br>* 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.<br>|
| Active Comparator: Young group<br>7 young participants (18-30 years) were included in physical inactivity or bed rest with supervised recovery intervent and underwent 14-day of bed rest. Bed rest was followed by 28-day recovery. During the bed rest participants will remain 24-hour horizontal with all daily activities performed lying in a bed. No social isolation will be forced. During the recovery participants will 3-times weekly per 75 minutes perform guided exercises to achieve baseline level. | Behavioral: physical inactivity or bed rest with supervised recovery<br>* 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.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in quadriceps muscle volume (young vs. old) after 14-day bed rest | Using MRI continous screening of single leg was performed | At baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in diameter of single fibre contractions (young vs. old) after 14-day bed rest | Biopsy samples were obtained from vastus lateralis muscles | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in peak aerobic power (VO2max) (young vs. old) after 14-day bed rest | graded cycling on sitting ergometer until exhaustion | baseline and after 14-day bed rest and on 14th day of recovery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in peak knee extensor force (young vs. old) after 14-day bed rest | Estimated from single leg isometric maximal voluntary contraction | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in lower limb explosive power (young vs. old) after 14-day bed rest | estimated from bilateral efforts on explosive ergometer (EXER) | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in gait stride length (young vs. old) after 14-day bed rest | Walking through the food placement detection system | baseline and after 14-day bed rest and on 14th and 400th day of recovery | 
| Change in insulin sensitivity (young vs. old) after 14-day bed rest | collected hourly for 6 hours after standard meal load as a measure of insulin sensitivity index | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in area-under-the curve (AUC) of triglycerides plasma concentration (young vs. old) after 14-day bed rest | collected hourly for 3 hours after standard meal load | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in N-telopeptide (young vs. old) after 14-day bed rest | From urine collection | baseline, during and after 14-day bed rest and during first 14 day of recovery | 
| Change in C-telopeptide (young vs. old) after 14-day bed rest | From urine collection | baseline, during and after 14-day bed rest and during first 14 day of recovery | 
| Change is contraction time (young vs. old) after 14-day bed rest | From Tensiomyographic response in vastus lateralis | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in force of single muscle fibre contraction (young vs. old) after 14-day bed rest | Biopsy samples were obtained from vastus lateralis muscles | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in specific force of single muscle fibre contraction (young vs. old) after 14-day bed rest | Biopsy samples were obtained from vastus lateralis muscles | baseline and after 14-day bed rest and on 14th day of recovery | 
| Change in velocity of single muscle fibre contraction (young vs. old) after 14-day bed rest | Biopsy samples were obtained from vastus lateralis muscles | baseline and after 14-day bed rest and on 14th day of recovery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ageing, Physical inactivity, Functional decline, Reconditioning