title: Six weeks of conditioning exercise increases total, but not free testosterone in lifelong sedentary aging men.
abstract: BACKGROUND
  Advancing age is associated with a gradual decline in circulating androgens, and the putative role of exercise training on systemic androgens remains to be adequately defined.
  
  
  METHODS
  The present investigation examined the impact of 6 weeks of supervised exercise training on resting levels of systemic hormones in a cohort of lifelong sedentary men [SED (n = 28), 62.5 ± 5.3 years], compared with a positive control group of age-matched lifelong exercisers [LE (n = 20), 60.4 ± 4.7 years, >30 years training history]. Blood hormones were sampled pre- and post-intervention from an antecubital forearm vein and analysed using electrochemiluminescent immunoassay. Cardiorespiratory fitness ([Formula: see text]) was determined via indirect calorimetry during an incremental cycle test to volitional exhaustion.
  
  
  RESULTS
  Analysis of variance (ANOVA) revealed a lack of significant change in any parameter amongst LE, whilst SED experienced a significant exercise-induced improvement in cardiorespiratory fitness and total testosterone (all p < 0.05). Concurrent increases in sex hormone-binding globulin (SHBG; p < 0.05) resulted in a lack of change to either bioavailable or calculated free testosterone (p > 0.05) amongst SED.
  
  
  CONCLUSIONS
  Although resting levels of systemic total testosterone increased in response to 6 weeks of exercise training, increases in SHBG negated any potential relationship between calculated-free or bioavailable testosterone. These findings indicate that increases in bioavailable testosterone fraction are not required for cardiorespiratory fitness improvements in aging men.
authors.affiliation: a School of Human Sciences, London Metropolitan University , London , UK .|b Institute of Clinical Exercise and Health Science, University of the West of Scotland , Hamilton , UK .
authors.forename: Lawrence D
authors.initials: LD
authors.lastname: Hayes
authors.affiliation: b Institute of Clinical Exercise and Health Science, University of the West of Scotland , Hamilton , UK .
authors.forename: Nicholas
authors.initials: N
authors.lastname: Sculthorpe
authors.affiliation: c School of Sport, Health and Outdoor Education, Trinity Saint David, University of Wales , Carmatrthen , UK , and.
authors.forename: Peter
authors.initials: P
authors.lastname: Herbert
authors.affiliation: b Institute of Clinical Exercise and Health Science, University of the West of Scotland , Hamilton , UK .
authors.forename: Julien S
authors.initials: JS
authors.lastname: Baker
authors.affiliation: d Department of Clinical Biochemistry , Royal Glamorgan Hospital , Pontyclun , Mid Glamorgan , UK.
authors.forename: Roberto
authors.initials: R
authors.lastname: Spagna
authors.affiliation: b Institute of Clinical Exercise and Health Science, University of the West of Scotland , Hamilton , UK .
authors.forename: Fergal M
authors.initials: FM
authors.lastname: Grace
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D000704:Analysis of Variance; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D064797:Physical Conditioning, Human / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D057185:Sedentary Behavior; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood*
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone
keywords: Aging; exercise; sex hormone-binding globulin; testosterone