Aerobic capacity and growth hormone deficiency after traumatic brain injury.
BACKGROUND
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.


METHODS
Subjects were screened for GH deficiency by the glucagon stimulation test and performed a maximal treadmill exercise test.


METHODS
Patients were studied in the postacute recovery phase after traumatic brain injury.


METHODS
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).


METHODS
There was no intervention.


METHODS
Aerobic capacity was assessed by measuring expired gases during a graded treadmill exercise test. One-way and two-way ANOVAs were carried out on all peak and submaximal cardiorespiratory variables, respectively. Appropriate post hoc comparisons followed as necessary.


RESULTS
Significantly higher peak oxygen consumption was found in traumatic brain injury subjects with GH normal vs. GH insufficient and deficient [26.4 +/- 6.9, 20.8 +/- 4.6, and 19.7 +/- 5.0, respectively (P < 0.05)]. Submaximal oxygen consumption 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.
Mossberg
Kurt A
KA
Department of Physical Therapy, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1144, USA. kmossber@utmb.edu
Masel
Brent E
BE
Gilkison
Charles R
CR
Urban
Randall J
RJ
D000293:Adolescent; D000328:Adult; D001930:Brain Injuries / Q000378:metabolism*; D015444:Exercise; D005080:Exercise Test; D019382:Human Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D010101:Oxygen Consumption
D019382:Human Growth Hormone