Effects of High Intensity Circuit Versus Traditional Strength Training on Physiological Responses in Trained Women

This study's purpose was to compare differences in strength and body composition following high intensity circuit training (HICT) and traditional strength training (TS) in trained women. Fourteen participants (28.5 ± 5.4 years, 160.7 ± 6.1 cm, 65.9 ± 11.7 kg) were randomly assigned to either the HICT group (HICT: n = 7) performing two short circuits with 5 min' rest between each series or the TS group (TS: n = 7) performing one exercise at a time, resting 3 min between sets. Both groups trained 3 days per week for 8 weeks [8-15 repetitions, three sets], close to muscular failure. Body composition, arm and thigh muscle girth, skinfold thickness, and 3RM on six different exercises were assessed before and after the intervention. Both groups similarly increased 3RM across all exercises (p < 0.001). There was a main effect of time (p < 0.001) for both groups on lean body mass indicating an increase in lean mass over time following both protocols, whereas body fat percentage decreased as a factor of time only (p = 0.04). There were no significant group or group × time interactions for any other variable. Therefore, both HICT and TS are similarly effective for increasing strength and lean body mass and decreasing body fat percentage in trained women. Those interested in maximizing time efficiency may prefer HICT, as these sessions took much less time to complete. Other variables such as exercise selection and personal preference should also be taken into consideration when choosing training style.