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Aerobic Capacity and Growth Hormone Deficiency after Traumatic Brain Injury


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This version published online on April 15, 2008

Journal of Clinical Endocrinology & Metabolism, doi:10.1210/jc.2008-0368


Submitted on February 14, 2008

Accepted on April 4, 2008


Aerobic Capacity and Growth Hormone Deficiency after Traumatic Brain Injury

Kurt A. Mossberg*, Brent E. Masel, Charles R. Gilkison, and Randall J. Urban


Department of Physical Therapy, University of Texas Medical Branch, Galveston, TX; Transitional Learning Center, Galveston, TX; Department of Medicine, University of Texas Medical Branch, Galveston, TX


* To whom correspondence should be addressed. E-mail: kmossber@utmb.edu


Context: Growth hormone (GH) deficiency occurs in approximately 20% of all individuals who suffer from a moderate to severe traumatic brain injury.


Objective: This study determined whether GH deficiency secondary to traumatic brain injury had an effect on aerobic capacity.


Design: Subjects were screened for growth hormone deficiency by the glucagon stimulation test and performed a maximal treadmill exercise test.


Setting: Patients were studied in the post-acute recovery phase after traumatic brain injury. Participants: Thirty-five individuals were studied. Groups were formed as follows: normal GH axis ? greater than 8 ng/mL response (n=12), insufficient ? GH 3-8 ng/mL response (n=11), and deficient ? less than 3 ng/mL response (n=12). Intervention: None. Main Outcome Measure: Aerobic capacity was assessed by measuring expired gases during a graded treadmill exercise test. One-way and two-way analyses of variance (ANOVA) were carried out on all peak and submaximal cardiorespiratory variables, respectively. Appropriate post hoc comparisons followed as necessary.


Results: Significantly higher peak VO2 was found in traumatic brain injury subjects with GH normal versus GH insufficient and deficient (26.4 ? 6.9, 20.8 ? 4.6 and 19.7 ? 5.0; respectively (p<0.05)). Submaximal VO2 was significantly higher in the GH normal group. All other variables were statistically similar.


Conclusions: This study shows that individuals with traumatic brain injury with normal GH secretion have below normal aerobic capacity and those patients who have GH insufficiency/deficiency are further deconditioned. Studies of GH replacement in these subjects should be conducted to assess whether GH therapy can improve cardiorespiratory fitness and prevent secondary disability

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Great article, Mary. It's so nice to have validation of something I already believed. My asthma, COPD, and sleep apnea didn't show up until AFTER I was in a car accident and all the hormonal symptoms 'just appeared'. I kind of figured there was a connection - this article goes into my file called: "See - told ya!"

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Mary, I'm so glad you posted this. I had a brain injury which caused my body to almost completely stop making growth hormone, and hitting my head made my Cushings symptoms go into high gear. I posted about my VO2 levels from my exercise test a few months ago, but no one was able to shed any light on it. Now I have some more because of you.



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