A Randomized Controlled Trial Comparing Two Different Approaches To Prescribe Exercise

Abstract

The Physical Activity Guidelines for Americans (PAG) recommend 150min/wk of moderate intensity aerobic physical activity (PA) plus 2days of muscle strengthening PA for health. Yet, 26% of Americans and 36% of college students perform no leisure time PA, stressing the need to increase PA in these populations. PURPOSE: We conducted a randomized controlled trial (RCT) comparing two different exercise prescription (ExRx) approaches to increase PA among college students. The purpose of this interim analysis was to assess differences in the Transtheoretical Model stage of change (SOC) and drop-out (DO) rates at the 6wk mid-point (6W) of the RCT compared to baseline (BL) between the two ExRx approaches. METHODS: 60 sedentary, healthy college students >18yr were randomized to two groups: ExRx #1 emphasized meeting the PAG via the Frequency, Intensity, Time, and Type or FITT principle of ExRx; and ExRx #2 emphasized that all PA counts. Both ExRx approaches progressed students from being sedentary to meeting weekly PA goals over the 12wk PA intervention. The primary RCT outcome was the change in PA volume at 12wk, assessed via accelerometer and the Paffenbarger PA Questionnaire. At BL and 6W students completed the SOC to measure PA action transitions over time. Height (cm) and weight (kg) were measured to calculate the body mass index (BMI) at BL. DO was calculated as those who ceased participation at 6W divided by the total randomized sample x100. RMANOVA tested if SOC differed over time by group and Chi-Square tested if DO differed between groups. RESULTS: Subjects (n=32) were sedentary, overweight (BMI=26.0+4.2 m2/kg), healthy college students (24.7+5.2yo) with no differences in BL characteristics between ExRx groups or DO and completers (>0.05). At 6W DO was 28.1% for the total sample with no differences between ExRx groups (p>0.05). At 6W SOC increased from BL in both ExRx groups (p<0.001), but to a greater level in ExRx #1 of 3.6+1.2 indicating progression from the contemplation to action stage than ExRx #2 of 2.7+1.0 indicating progression from the contemplation to preparation stage (p=.045). DISCUSSION: Improvements in SOC suggest PA increased with both ExRx approaches at 6W. Whether these SOC improvements persist at 12wk and translate into greater increases in PA and lower DO remains to be determined.