Sports Medicine: Just the Facts

CHAPTER 32 • ENDOCRINE CONSIDERATIONS 183

•Effects of resistance training are difficult to study
because of pulsatile release requiring frequent sampling.

• Chronic exercise: Conflicting data require further
  investigation; adaptation and mechanisms remain
  unknown.
  •Godfrey et al (2003) report decreased resting GH
  values and blunted exercise-induced GH release with
  chronic endurance training.
  •Wideman et al (2002) report aerobically trained females
  training at intensities greater than the lactate threshold
  experience a twofold increase in 24-h GH release.
  
  
  • GH release was not significant in those who trained at
    or below the lactate threshold (Weltman et al, 1992)
  
  
  
  


• Short-term GH release appears to be blunted with
  exercise training
  
  
  • GH was reduced within 3 weeks of exercise train-
    ing, decreasing further at 6 week measurement
    (Weltman et al, 1997).
  
  
  • Decline may be due to increased tissue sensitivity
    and/or enhanced clearance.
  
  
  
  


• As a result of difficulty in measurement, the impact of
  chronic resistance training remains relatively unknown.

B. Thyroid Stimulating Hormone

• Endurance exercise/resistance exercise:Six rowers
  underwent 3 weeks of high intensity resistance train-
  ing followed by 3 weeks of endurance training.
  
  
  1. Each 3 weeks was separated by a week of rest.
  
  
  2. Investigators found a significant decline in thyroid
     stimulating hormone(TSH) which continued to
     decrease during the rest period.
     3.At the start of the endurance training, TSH increased.
  
  
  3. Values returned to baseline during the subsequent
     rest period (Simsch et al, 2002).
     •Following 6 weeks of endurance training, TSH
     remained unchanged in recreational athletes (Lehmann
     et al, 1993).
  
  
  
  

C. Adrenocorticotropic Hormone

• Endurance exercise: Repetitive bouts (2) of aerobic
  exercise at 75% Vo2max demonstrate a significant
  increase in adrenocorticotropic hormone (ACTH)
  during and after the second bout; each bout was fol-
  lowed by 3-h rest (Ronsen et al, 2001).


• Aerobic exercise to exhaustion revealed a significant
  acute increase in ACTH when compared to resting
  values (de Diego et al, 2001).


• Postmenopausal women undergoing exhaustive bicy-
  cle exercise experienced a pronounced ACTH increase
  immediately following the exercise session (Pompe
  van der et al, 2001).


• Resistance exercise: High intensity (load 100%)
  showed a significantly greater increase in ACTH when
  compared to moderate intensity (70% load) (Raastad
  et al, 2000).
  
  
  • Heavy resistance training significantly increased
    ACTH in young and older men.
    
    
    • The levels in younger men remained elevated
      throughout 30 min of recovery (Kraemer et al,
      1998).
    
    
    
    
  
  
  • Exercise training: Prolonged endurance training in
    recreational athletes (6 weeks) revealed a significant
    increase in ACTH after training period (Lehmann et al,
    1993).
  
  
  • Endurance trained individuals had comparable resting
    ACTH values as their sedentary counterparts (Duclos
    et al, 2001).
  
  
  
  

D. Luteinizing Hormone/Follicle-Stimulating

Hormone

• Endurance exercise:Four successive days of low
  intensity, long duration (8 h) walking revealed the
  following:
  
  
  1. Decreased luteinizing hormone(LH) during the 1st
     and 2nd days by 31%.
     2.Follicle-stimulating hormone (FSH) suppression
     occurred each day after day 2 (19%) when com-
     pared to resting values.
  
  
  2. LH returned to baseline following the 4-day exer-
     cise protocol, whereas FSH maintained its exercise
     value (Vaananen et al, 2002).
  
  
  
  


• Resistance exercise: LH and FSH showed no
  response to high or moderate intensity strength exer-
  cise (Raastad et al, 2000).


• Chronic exercise: Six weeks of endurance training in
  male recreational athletes had no influence on base-
  line or exercise serum LH or FSH.
  
  
  • After training period, FSH synthesis–secretion capac-
    ity was increased whereas LH synthesis–secretion
    capacity was decreased (Lehmann et al, 1993).
    •Vasankari et al (1993) showed increased FSH in
    endurance trained male athletes with years of physical
    training.
  
  
  
  


• Baseline and post race LH and FSH were not signifi-
  cantly different when comparing two elite cycling
  teams, one of which had more racing days than the
  other (Fernandez-Garcia et al, 2002).

E. Prolactin

• Endurance exercise: Plasma prolactin (PRL) was
  significantly increased following an acute graded,
  maximal treadmill test (Dohi et al, 2003).


• Cyclists involved in a 3-week stage competition
  showed a significant increase in PRL between week 1
  and week 2 (Fernandez-Garcia et al, 2002).


• Postmenopausal women performing exhaustive aero-
  bic exercise experienced a 114% increase (peak) in
  PRL 15 min postexercise (Pompe van der et al,
  2001).


• Resistance exercise: Relatively unknown