Adaptive Responses of Cardiorespiratory Fitness and Cardiometabolic Risk Factors to Polarized Versus Other Types of...

This study aimed to investigate the effects of 10-week interventions of polarized training (POL), high-intensity interval training (HIIT), and threshold training (THR) on cardiorespiratory fitness (CRF) and cardiometabolic risk factors in untrained, healthy, young obese females. A total of 40 obese, untrained females volunteered to participate in the study and were randomly allocated to four equal groups: POL, HIIT, THR, and a control (CON) group. Training intensity was prescribed relative to ventilatory thresholds (VTs) and categorized into three zones: Zone 1 (Z1; 95% VT₁), Zone 2 (Z2; 50% to 95% VT₂), and Zone 3 (Z3; 90% VO_2max). All the training groups performed similar training loads (66% to 93% heart rate max) and the weekly intensity distribution was 75% Z1 and 25% Z3 for POL, 100% Z3 for HIIT, and 50% Z1 and 50% Z2 for THR. CRF, glycemic and lipid profiles, body composition, and cardiovascular variables were assessed before and after the 10-week intervention. After the intervention, total body mass, fat mass, heart rate, fasting glucose, cholesterol, LDL and triglyceride decreased in all exercised-groups (time effect: p < 0.001). In addition, the VO_2max, VT₁, VT₂, Q_max and SV_max increased in all exercised-groups (time effect: p < 0.001) following the 10-week intervention period. Moreover, the POL group showed more adaptive responses than the HIIT and THR training modalities for the changes in the CRF, glycemic and lipid profiles, body composition, and HR (interaction effect: p ≤ 0.002) after the 10-week training. In summary, aerobic training models characterized by different intensity distributions are effective in improving CRF, cardiometabolic risk factors, and body composition. However, compared with HIIT and THR, POL elicited superior adaptations across a broader range of CRF and cardiometabolic variables. Collectively, these findings indicate that polarized volume training represents an effective non-pharmacological strategy for simultaneously enhancing CRF and reducing cardiometabolic risk in young, untrained women with obesity.