Heart rate recovery is lower following supine exercise in asymptomatic hereditary hemochromatosis subjects compared with healthy controls.
BACKGROUND
Heart rate recovery (HRR) has become an important diagnostic and prognostic marker in recent years. Subjects with hereditary hemochromatosis (HH) demonstrate arterial wall changes that reduce compliance. Arterial compliance may influence HRR by altering baroreceptor discharge. The purpose of the present study is to examine differences in HRR between subjects with HH and healthy controls during treadmill (TM) and supine lower extremity ergometry (SLEE) exercise testing.


METHODS
Forty subjects with asymptomatic HH (27 men/13 women; mean age: 49.7 +/- 9.9 years) and 21 healthy controls (14 men/7 women; mean age: 47.8 +/- 8.4 years) participated in this study. Each subject underwent a symptom-limited 25-W Supine Lower Extremity Ergometry (SLEE) and Bruce TM exercise test within 1 week of each other. Heart rate recovery was the value obtained at 1 minute postexercise. Peak heart rate, systolic blood pressure, and the double product were also obtained during each exercise test.


RESULTS
Peak heart rate was significantly higher, whereas HRR and peak systolic blood pressure were significantly lower during TM compared with SLEE exercise testing in both groups (P < .01). A significantly lower HRR during SLEE in subjects with HH was the only significant difference between groups (35.4 +/- 9.0 vs. 29.2 +/- 8.5, P < .01).


CONCLUSIONS
Heart rate recovery was not significantly different between HH and control subjects during upright exercise. However, HRR was significantly lower during SLEE in HH subjects compared with controls. A higher venous return during SLEE may have allowed for differences in arterial compliance between groups to influence HRR.
Arena
Ross
R
Department of Physical Therapy, Virginia Commonwealth University, VA 23298-0224, USA. raarena@vcu.edu
Shizukuda
Yukitaka
Y
Bolan
Charles D
CD
Tripodi
Dorothy J
DJ
Yau
Yu-Ying
YY
Smith
Kevin P
KP
Waclawiw
Myron A
MA
Leitman
Susan F
SF
Rosing
Douglas R
DR
D001794:Blood Pressure / Q000502:physiology; D016022:Case-Control Studies; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006432:Hemochromatosis / Q000235:genetics / Q000503:physiopathology*; D006801:Humans; D007501:Iron / Q000097:blood; D008297:Male; D008875:Middle Aged; D020127:Recovery of Function / Q000502:physiology*; D016683:Supine Position / Q000502:physiology; D013599:Systole / Q000502:physiology
D007501:Iron