Physical activity appears to be an important lifestyle habit to achieve healthy aging by promoting autonomy and quality of life. Interestingly, the dramatic changes that the human body undergoes due to bedrest for illnesses and hospitalization are similar to those seen over decades of normal aging. Bedrest in otherwise healthy older individuals can lead to a reduction of muscle size and strength, changes in bone strength and function of the heart and blood vessels. Bedrest can also lead to changes in keeping proper balance as well as changes in processing and understanding information. All of these factors negatively affect activities of daily living leading to physical function impairment and development of frailty, a clinical condition associated with an increased risk for disease and death. The purpose of this study is to investigate whether exercise can counteract the negative effects of 2-week head tilt down bed rest on muscle function and metabolism, postural control, bone structure, orthostatic tolerance and cognitive function in adults. For this study the investigators will recruit 24 healthy men and women between 55 - 65 years of age. All subjects will spend a total of 26 days (5 days of adaption period, 14 days of bed rest with 6 degrees of downward inclination, and 7 days of recovery period) at the McGill University Health Centre (MUHC). During this study, 12 subjects will randomly undergo an exercise intervention as countermeasure during the 14 days of bed rest period and 12 will serve as control. Each subjects participation in this study will involve 1 telephone call (pre-screening) and 4 visits at the MUHC: 1 screening visit (Visit 1) followed by a 26-day long visit (Visit 2) and 2 follow-up visits (Visit 3 and Visit 4). During Visits 2 - 4 various measurements will be performed to assess sensorimotor control, muscle function and metabolism, bone structure, cardiovascular function, cognitive performance and function, and specimen collection (blood, urine, saliva, feces and muscle tissue).
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Changes in cognition status of participants with head down bed rest (HDBR) with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in cognition status of participants with head down bed rest (HDBR) with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in emotional status of participants with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in emotional status of participants with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in brain structure with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in brain function with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in muscle muscle mass with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in muscle fat infiltration with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in adiposity with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in ventricular volume of the heart with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in ventricular mass with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in bone structure with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in muscle strength with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in muscle strength with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in muscle-pump baroreflex with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in balance control with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in orthostatic tolerance with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Cardiac and vascular changes with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Cardiac and vascular changes with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Cardiac and vascular changes with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Cardiac and vascular changes with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in Fractional Synthesis Rate (FSR) with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: during HDBR period
Changes in sleep quality with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in sleep architecture with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in frailty status with HDBR with and without exercise countermeasure.
Timeframe: Throughput the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in the gut microbiome with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in the constitution of the oral microbiome with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline, HDBR and Recovery periods
Changes in physical performance with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in physical performance with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in dynamic balance with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in bone markers with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in growth factors with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods
Changes in cytokines with HDBR with and without exercise countermeasure.
Timeframe: Throughout the 26-day study period: at Baseline and Recovery periods