Blood Pressure Responses Following Continuous Versus Fractionalized Exercise In Young Adults

Abstract

Training with multiple short bouts of exercise may be effective for improving some measures of health and fitness. Little is known about the acute effects of fractionalized exercise vis-à-vis traditional single bout exercise. PURPOSE: We compared the effects of continuous vs. fractionalized exercise (Ex) on blood pressure (BP) responses in lean (L) and obese (O) young adults. (Males- Lean n=8, age=23.3 yr, BMI=23.7, VO2 peak=38.3 ml/kg/min; Obese n=8, age=30.6 yr, BMI=33.3, VO2 peak=28.5 ml/kg/min; Females- Lean n=7, age=25.7 yr, BMI=22.6, VO2 peak=31.4 ml/kg/min; Obese n=7, age=28.8 yr, BMI=36.6, VO2 peak=18.2 ml/kg/min). METHODS: Subjects were admitted to the General Clinical Research Center on 3 randomly assigned occasions: control (C), one 30 min bout of Ex (0900-0930h, 1X30) and three 10 minute bouts of Ex (0920-0930h, 1320-1330h, 1520-1530h, 3X10) (Ex intensity= 50% of the difference between lactate threshold and VO2 peak). Identical meals were served at 1000h, 1400h, and 1800h. BP and HR were measured hourly from 0900h-2100h. BP values were collapsed and analyzed in three time blocks. (0900-1200, 1300-1600, 1700-2000). Data were analyzed with 2-way REANOVA with multiple comparison adjustment. RESULTS: For systolic blood pressure (SBP), significant main effects were observed for gender, with women exhibiting lower SBP than men (P<0.001) and condition, with the 3x10 exercise condition resulting in lower SBP than the 1x30 and control conditions (p=0.05) with SBP decreasing over the course of the day (p=0.04). A trend for a main effect of obesity was also observed (p=0.16) with obese subjects having higher SBP than non-obese subjects. A condition-by-time interaction was observed (p=0.02) with greater decreases in SBP observed in the 3x10 exercise condition than the 1x30 and control conditions. No significant differences were observed for diastolic blood pressure or heart rate across the three exercise conditions. CONCLUSION: Fractionalized exercise may have utility in the reduction of systolic blood pressure in some young adults. Supported in part by a NIH grant to the General Clinical Research Center RR-00847