Prediction of maximal heart rate in individuals with mental retardation.
OBJECTIVE
It is well known that individuals with mental retardation (MR), especially those with Down syndrome (DS), have low maximal heart rates (MHR). We evaluated the ability to predict MHR in individuals with MR and DS in comparison with persons without MR.


METHODS
Subjects completed a maximal exercise test on the treadmill with metabolic and HR measurements. Stepwise multiple regression was used to develop prediction equations for subjects with MR (N = 276; 97 with DS) and without (N = 296) MR, ranging in age from 9-46 yr.


RESULTS
Subjects with MR exhibited significantly lower MHR (177 vs 185 beats.min(-1)) and VO2peak (33.8 vs 35.6 mL.kg-1.min(-1)). In subjects with MR, age was a poor predictor of MHR, Y = 189 - 0.59 (age) (R = 0.30, SEE = 13.8 beats.min-1; P < 0.01), but age was a better predictor for subjects without MR, Y = 205 - 0.64 (age) (R = 0.52, SEE = 9.9 beats.min(-1); P < 0.01). A large sample Z test indicated that these regression coefficients were significantly different (P < 0.01). However, adding DS to the regression improved the prediction for subjects with MR, Y = 210 - (0.56 age) - (15.5 DS) (R = 0.57; SEE = 11.8 beats.min(-1), P < 0.01).


CONCLUSIONS
MHR can be predicted with similar accuracy in subjects with and without MR, provided DS is accounted for in the equation for the subjects with MR.
Fernhall
B
B
Exercise Science Programs, The George Washington University Medical Center, Washington, DC, USA. bfernhal@syr.edu
McCubbin
J A
JA
Pitetti
K H
KH
Rintala
P
P
Rimmer
J H
JH
Millar
A L
AL
De Silva
A
A
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D002648:Child; D004314:Down Syndrome / Q000150:complications / Q000503:physiopathology*; D006339:Heart Rate / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008607:Intellectual Disability / Q000150:complications / Q000503:physiopathology*; D008875:Middle Aged; D012044:Regression Analysis; D012189:Retrospective Studies