Mechanical Muscle Function and Lean Body Mass During Supervised Strength Training and Testosterone Therapy in Aging Men with Low-Normal Testosterone Levels Thue Kvorning, PhD,* Louise L. Christensen, MD, PhD,† Klavs Madsen, PhD,‡ Jakob L. Nielsen, MSc,* Kasper D. Gejl, MSc,* Kim Brixen, MD, PhD,† and Marianne Andersen, MD, PhD†
OBJECTIVES: To examine the effect of strength training and testosterone therapy on mechanical muscle function and lean body mass (LBM) in aging men with low-normal testosterone levels in a randomized, double-blind, placebocontrolled 24-week study. DESIGN: Randomized, double-blind, placebo-controlled. SETTING: Odense, Denmark. PARTICIPANTS: Men aged 60 to 78, with bioavailable testosterone levels of less than 7.3 nmol/L and a waist circumference greater than 94 cm were randomized to testosterone (50–100 mg/d, n = 22) placebo (n = 23) or strength training (n = 23) for 24 weeks. The strength training group was randomized to addition of testosterone or placebo after 12 weeks. Subjects performed supervised strength training (2–3 sets with 6- to 10-repetition maximum loads, 3 times per week). MEASUREMENTS: Testosterone levels, maximal voluntary contraction and rate of force development, and LBM were obtained at 0 and at Weeks 12 and 24 of the intervention. RESULTS: No changes in any variables were recorded with placebo. In the strength training group, maximal voluntary contraction increased 8% after 12 weeks (P = .005). During the following 12 weeks of strength training rate of force development increased by 10% (P = .04) and maximal voluntary contraction further increased (P < .001). Mechanical muscle function was unchanged in men receiving only testosterone for 24 weeks. LBM increased only in men receiving testosterone (P = .004).
From the *Institute of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense; †Department of Endocrinology, Odense University Hospital and Institute of Clinical Research, University of Southern Denmark, Odense; and ‡Section for Sport Science, Aarhus University, Aarhus, Denmark. Clinical Trial Registration Number: NCT00700024 Address correspondence to Thue Kvorning, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. E-mail:
[email protected] DOI: 10.1111/jgs.12279
JAGS 61:957–962, 2013 © 2013, Copyright the Authors Journal compilation © 2013, The American Geriatrics Society
CONCLUSION: Strength training in aging men with lownormal testosterone levels may improve mechanical muscle function, but this effect occurs without a significant increase in LBM. Clinically, only the combination of testosterone therapy and strength training resulted in an increase in mechanical muscle function and LBM. J Am Geriatr Soc 61:957–962, 2013.
Key words: testosterone (therapy); strength training; muscle strength; lean body mass; aging
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estosterone therapy is indicated in primary or secondary hypogonadism,1,2 although there is no consensus on testosterone treatment in aging men with low-normal testosterone levels.3,4 These men often have a decrease in lean body mass (LBM) and muscle strength and, in most cases, impaired physical function as well.5,6 Supraphysiological testosterone therapy in men with low testosterone levels is associated with an increase in LBM, but a similar increase in muscle strength does not occur.7,8 Moreover, the effect of testosterone therapy on muscle strength and performance using physiological doses has not been extensively studied, and existing studies are not conclusive. One study showed improved muscle strength after 12 months of intervention,9 and another supported these findings after only 6 months of intervention, but testosterone levels were at the high end of the physiological range,10 but two other studies reported no effect on muscle strength after 361 and 611 months of physiological testosterone doses. Accordingly, it has been argued that increases in LBM in elderly adults are less meaningful without concomitant improvements in performance-related measures (muscle strength).12 The aim of this study was first to investigate the effect of strength training on mechanical muscle function (isometric strength (maximum voluntary contraction (MVC)), dynamic strength (10-repetition maximum (RM)), rate of force development (RFD), and jump height
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(JH)), as well as testosterone levels and LBM in aging men with low-normal bioavailable testosterone levels. In addition, the effects of strength training and testosterone therapy were compared, as well as the effect of combined testosterone therapy and strength training on the abovementioned variables.
METHODS Details of the study design have been reported elsewhere.13 Briefly, the study was a single-center, randomized, double-blind, placebo-controlled study to assess the effect of testosterone gel and strength training on mechanical muscle function, body composition, components of the metabolic syndrome, and quality of life in men aged 60 to 78 with low-normal bioavailable testosterone levels (
