Cardiorespiratory fitness reduces the risk of incident hypertension associated with a parental history of hypertension.

Family history of hypertension increases the risk of an individual to develop hypertension, whereas moderate-to-high cardiorespiratory fitness has the opposite effect. However, the joint association of each on the development of hypertension is not well understood. We studied fitness and incident hypertension in 6278 participants who were given a preventative medical examination. Thirty-three percent reported a parent with hypertension, and there were 1545 cases of incident hypertension after a mean of 4.7 years. The presence of parental hypertension was associated with a 28% higher risk of developing hypertension after adjustments for age, sex, and examination year. After further adjustments for smoking, alcohol intake, resting systolic and diastolic blood pressures, hypercholesterolemia, body mass index, physical inactivity, and fitness, there was a 20% higher risk associated with parental hypertension. After adjusting for age, sex, and examination year, both moderate and high levels of fitness were associated with lower risk for developing hypertension by 26% and 42%, respectively. In the joint analysis, individuals with both a low level of fitness and a parent with hypertension exhibited a 70% higher risk for developing hypertension compared with high fit individuals with no parental history (P = 0.004). However, individuals with a high level of fitness and a parent with hypertension only experienced a 16% higher risk of developing hypertension compared with fit individuals with no parental history (P = 0.03). The significantly lower risk of developing hypertension when progressing from low- to high-fit groups among those with a parental history of hypertension has important clinical implications.