Peaks and Valleys

In this issue of Hypertension , Rankinen et al1 report on a genome scan for gene loci related to exercise-induced blood pressure elevations from the HERITAGE Family Study. The investigators studied 344 sibling pairs from 99 white nuclear families and 102 sibling pairs from 104 black nuclear families. The hypothesis was that linkage (the question, “where is it?”) could be found between certain gene loci and blood pressure elevations at baseline, after acute exercise, and after exercise training. The subjects were tested at 50 watts (tooth brushing equivalent) and 80% of VO2 maximum (fairly hard work). The subjects underwent an exercise training program involving 30-minute sessions, which were gradually increased to 50 minutes, 3 times weekly for at least 6 weeks. Thereafter, the subjects were retested, and the difference (Δ) values were tested as phenotypes to examine a training effect.See p 30 The authors are to be congratulated for tackling a highly clinically relevant hypothesis in a search for new genes related to blood pressure changes with fitness. Their data (decrease in maximal blood pressure in response to exercise 50 W) showed that the training responses were profound. The family fathers showed a 16 mm Hg drop in Δ systolic blood pressure and a 7 mm Hg drop in Δ diastolic blood pressure with training. The mothers’ drops in blood pressure were almost as good and exhibited similar impressive changes. The children were decidedly less responsive, although they also showed a significant decrease in exercise-induced blood pressure. Presumably, the children were more fit at baseline. At the higher workload, the results were less impressive. Heart rate, also an interesting parameter of fitness, was not examined in this study. Gene loci for heart rate have been identified in the rat and would be an interesting subject of investigation. …