• body composition
• fat distribution
• strength
• power
• function

• Blood chemistries [ Time Frame: Baseline, 6 and 12 months ] [ Designated as safety issue: Yes ]
• Transrectal ultrasound [ Time Frame: Baseline and 12 months ] [ Designated as safety issue: Yes ]
• Digital rectal exam [ Time Frame: Baseline, 6 and 12 months ] [ Designated as safety issue: Yes ]
• Obstructive sleep apnea [ Time Frame: Baseline, 6 and 12 months ] [ Designated as safety issue: Yes ]
• Maximal oxygen volume uptake [ Time Frame: Baseline and 12 months ] [ Designated as safety issue: Yes ]
• Benign prostatic hyperplasia [ Time Frame: Baseline, 6 and 12 months ] [ Designated as safety issue: Yes ]

• cognition
• vascular reactivity
• obstructive sleep apnea
• testosterone
• estradiol
• dehydroepiandrosterone (DHEA)
• insulin-like growth factor I
• insulin resistance

The purpose of this study is to evaluate the effects of testosterone supplementation (AndroGel) on body composition, strength, endurance, cognition, and function in older men.

Studies suggest that testosterone (T) replacement in healthy elderly men has beneficial effects on body composition, muscle, bone, memory, and behavior, but the risks of chronic treatment, especially on the prostate, heart, and sleep quality, are not entirely clear. Therefore, it is most desirable to supplement into the lowest "effective" range in elderly men. However, the effects of lower than usual replacement T doses have not been well studied. Furthermore, the possible important interaction of exercise to enhance the positive effects of T supplementation, yet mitigate the possible side effects, has not been studied in older men.

This one-year study will enroll 150 men with low-normal to slightly below normal serum total T levels. Participants will be randomized into one of 6 treatment groups to receive T supplementation (AndroGel) of 25mg/day, 50 mg/day or a placebo crossed with progressive resistance training (PRT) exercise 3 times a week versus none. At the end of the study, participants in the exercise-control group will be offered PRT.

• Drug: Testosterone Gel
• Behavioral: Exercise - Progressive Resistance Training (PRT)
• Drug: Placebo Gel

• Experimental:

  Low Dose Testosterone Group applies one 2.5 gm active packet and one placebo packet, titrated to a target blood range of 400-550 pg/ml)

  1 year standard PRT program

• Experimental:

  Low Dose Testosterone Group applies one 2.5 gm active packet and one placebo packet, titrated to a target blood range of 400-550 pg/ml)

  No exercise program

• Experimental:

  High Dose Testosterone Group applies two 2.5 gm active packets, titrated to a target blood range of 600-1000 pg/ml)

  1 year standard PRT program

• Experimental:

  High Dose Testosterone Group applies two 2.5 gm active packets, titrated to a target blood range of 600-1000 pg/ml)

  No exercise program

• Active Comparator:

  Placebo Group applies two 2.5 gm placebo packets

  1 year standard PRT program

• Placebo Comparator:

  Placebo group applies two 2.5 gm placebo packets

  No exercise program

• Schwartz RS, Shuman WP, Bradbury VL, Cain KC, Fellingham GW, Beard JC, Kahn SE, Stratton JR, Cerqueira MD, Abrass IB. Body fat distribution in healthy young and older men. J Gerontol. 1990 Nov;45(6):M181-5.
• Porter MM, Vandervoort AA, Lexell J. Aging of human muscle: structure, function and adaptability. Scand J Med Sci Sports. 1995 Jun;5(3):129-42. Review.
• Jolles J, Verhey FR, Riedel WJ, Houx PJ. Cognitive impairment in elderly people. Predisposing factors and implications for experimental drug studies. Drugs Aging. 1995 Dec;7(6):459-79. Review.
• Davidson JM, Chen JJ, Crapo L, Gray GD, Greenleaf WJ, Catania JA. Hormonal changes and sexual function in aging men. J Clin Endocrinol Metab. 1983 Jul;57(1):71-7.
• Vitiello MV. Sleep disorders and aging: understanding the causes. J Gerontol A Biol Sci Med Sci. 1997 Jul;52(4):M189-91. Review. No abstract available.
• Myers BL, Badia P. Changes in circadian rhythms and sleep quality with aging: mechanisms and interventions. Neurosci Biobehav Rev. 1995 Winter;19(4):553-71. Review. Erratum in: Neurosci Biobehav Rev 1996 Summer;20(2):I-IV.

Inclusion Criteria:

• Generally healthy, untrained men over 60 years old with low-normal testosterone levels (200-350ng/dL)
• Must reside in the Denver metro area

Exclusion Criteria:

• Prostate/breast cancer
• Unable to exercise safely
• severe obesity (>34 body mass index [BMI])
• Polycythemia
• Diabetes
• Current smoker