Isometric exercise training lowers resting blood pressure

Both rhythmic and “resistive” (weight lifting) exercise training can produce modest decreases in resting blood pressure. The next logical point along an exercise continuum consisting of different proportions of rhythmic and isometric efforts is a strictly isometric effort. The purpose of these studies was to assess the effects of isometric, handgrip exercise training on resting blood pressure. To avoid the extreme pressor responses elicited by fatiguing isometric efforts, the isometric exercise training used in this study consisted of brief handgrip contractions separated by rest periods. Modest repeated rises in systolic and diastolic pressures therefore served as the putative stimuli for training adaptations in resting blood pressures. Human subjects in study 1 trained with four, 2-min isometric handgrip contractions with 3-min rests between contractions. The intensity of the contractions was equal to 30% of their maximal effort for each day. The bouts of isometric exercise were performed three times per week for 8 wk. Study 2 training consisted of four contractions of 50% of maximum effort held for a duration of 45 s with 1-min rests. These were performed 5 d-wk^-1 for 5 wk. In Study 1, all eight trained subjects had a significant decline in both systolic and diastolic resting blood pressures, with group averages of 12.5 and 14.9 mm Hg, respectively. Seven matched control subjects who did not train had no change in resting pressures. In study 2, subjects were trained in their home or workplace and experienced significant mean declines in resting systolic and diastolic pressures of 9.5 and 8.9 mm Hg. In a follow-up period of 5 additional weeks in which no isometric training occurred, resting blood pressures gradually returned to a level not different from pressures preceding training. These results demonstrate a hy-potensive effect of isometric exercise training at least as great as other nonpharmacological interventions.