This will be a randomized, placebo-controlled, parallel group, double blind, clinical trial in community dwelling, older men, 65 years of age or older, who have mobility limitation and low protein intake. The study will have a 2 X 2 factorial design, which will allow us to investigate the effects of dietary protein intake and testosterone separately and together.
The recommended dietary allowance (RDA) for protein, set at 0.8 grams/kg/day for adult men and women, has engendered debate and many experts advocate protein intakes substantially above the RDA to help maintain muscle anabolism in older individuals. It is not known whether increasing protein intake in older Americans, whose current intake is below the RDA, increases skeletal muscle mass, muscle performance and physical function. Our first aim is to determine whether administration of 1.3 g/kg/day of protein, compared to the RDA (0.8 g/kg/day), will result in greater improvements in lean body mass, maximal voluntary muscle strength and power, and self-reported and performance-based measures of physical function in older men. Our second aim is to determine whether the gains in lean body mass, maximal voluntary strength and self-reported and performance-based measures of physical function during testosterone administration are greater with 1.3 g protein than with the RDA in older men on a eucaloric diet. We will conduct a randomized, placebo-controlled, double-blind trial using a 2 X 2 factorial design. Community dwelling men, 65 years or older, who have self-reported mobility limitation, a daily protein intake of \<0.8 g/kg/day and no contraindications for testosterone therapy, will be randomly assigned to one of four groups: placebo injections plus protein 0.8 g/kg/day; placebo injections plus protein 1.3 g/kg/day; testosterone enanthate 100 mg weekly plus protein 0.8 g/kg/day; testosterone enanthate 100 mg weekly plus protein 1.3 g/kg/day. Treatment duration will be 6 months. The primary outcome is change in lean body mass from baseline to 6 months, measured by dual energy X-ray absorptiometry. Secondary outcomes include change in maximal voluntary strength in leg and chest press exercises, leg power, self-reported (physical function domain of SF-36) and performance-based measures of physical function (6-min walking distance and speed, stair climbing power, and load carrying), fatigue, well-being and affectivity balance. Safety measures include urinary calcium excretion, hematocrit, prostate specific antigen (PSA) and prostate examination.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
92
Testosterone enanthate 100 mg intramuscularly weekly
Testosterone enanthate 100 mg intramuscularly weekly
Brigham and Women's Hospital
Boston, Massachusetts, United States
Change in Lean Body Mass as Measured by Dual Energy X-ray Absorptiometry (DXA)
Primary outcome is change in lean body mass, measured by dual energy X-ray absorptiometry (DXA)
Time frame: 6 months from baseline
Change of Maximal Voluntary Strength
Tests of Muscle Performance: (1) Maximal voluntary strength measured by 1-repetition maximum method in leg press; (2) Maximal voluntary strength in chest press; this exercise was chosen because it involves the large muscle groups of the upper extremities.
Time frame: 6 months from baseline
Change of Leg Press Power
Muscle Performance measured using Power of hip and knee extension by Bassey's leg rig.
Time frame: 6 months from baseline
Change of 6-minute Walking Distance
Tests of Physical Function and Task-Specific Performance measured by 6-min walking distance
Time frame: 6 months from baseline
Change of Stair Climbing Tests
Tests of Physical Function and Task-Specific Performance measured by Stair-climbing power +/- 20% load carry. Physical Function was evaluated using two tests of stair climb power using an indoor 12-step staircase. One test consisted of ascending the 12-steps as rapidly as possible without running (unloaded stair climb) while the second test required participants to carry a load equivalent to 20% of their baseline body weight evenly distributed in two canvas tote bags (loaded stair climb). Time to ascend the stairs was measured electronically with a digital clock and switch mats placed at the base of the steps and on the 12th step. Power in watts is calculated by the following: \[body weight (kilograms) \* distance (meters)/ (time/60)\] /6.12.
Time frame: 6 months from baseline
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Change of 50-meter Loaded Walking Test
Tests of Physical Function and Task-Specific Performance measured by 50-meter timed walk + 20% load carry. Physical Function was evaluated using test of 50-meter loaded walking speed. The test required participants to carry a load equivalent to 20% of their baseline body weight evenly distributed in two canvas tote bags. Time was measured electronically with a digital clock. Speed in meters per second is calculated by the following: 50/time.
Time frame: 6 months from baseline
Change of Self-reported Physical Function Domain of Short Form Health Survey (SF-36)
36-Item Short Form Health Survey (SF-36) is a set of generic, coherent, and easily administered quality-of-life measures. Physical function domain of the Medical Outcomes Study Short Form-36 (SF-36) contains 10 items with the score range of 0-100. Higher score yields better performance.
Time frame: 6 months from baseline
Change of Psychological Well Being Index (PGWBI)
The PGWBI is a 22-item health-related Quality of Life (HRQoL) questionnaire developed in US which produces a self-perceived evaluation of psychological well-being expressed by a summary score. The 22 items are grouped in 6 dimensions. A global score is computed as the sum of all items with range of 0-110. A higher score yields better performance.
Time frame: 6 months from baseline
Change of Functional Assessment of Chronic Illness Therapy (FACIT) Fatigue Scale
The FACIT Fatigue Scale is a 13-item questionnaire that measures an individual's level of fatigue during their usual daily activities over the past week. The level of fatigue is measured on a four point scale (4 = not at all fatigued to 0 = very much fatigued). Score ranges 0-52. The higher the score, the better the quality of life.
Time frame: 6 months from baseline
Change of Derogatis Affective Balance Scale (DABS)
The Derogatis Affects Balance Scale (DABS) is a multidimensional self-report mood and affects inventory comprised of 40 adjective-items using a 5-point Likert style scale. The DABS global scores consist of the Positive Total score (PTOT), Negative Total score (NTOT), where The Positive Affects Total (PTOT) is defined as the sum of all scores on the four positive affects dimensions of joy, contentment, vigor and affection, ranging 0-80. Similarly, the Negative Affects Total (NTOT) is represented as the sum of scores on the four negative dimensions of anxiety, depression, guilt and hostility, ranging 0-80. The Affects Expressiveness Index (AEI) is defined as the sum total of PTOT and NTOT, ranging 0-160. Higher score yields stronger affective intensity.
Time frame: 6 months from baseline