Weight loss but not gains in cardiorespiratory fitness after exercise-training predicts improved health risk factors in metabolic syndrome

Abstract

Background and aims: To examine the relationship between changes in cardiorespiratory fitness (CRF; estimated by VO₂max) and metabolic syndrome (MetS) after an exercise training intervention to confirm/contradict the high association found in cross-sectional observational studies.

Methods and results: MetS individuals (54 ± 8 yrs old; BMI of 32 ± 5) were randomly allocated (6:1 ratio) to a group that exercised trained for 16-weeks (EXER; n = 138) or a control sedentary group (CONT; n = 22). At baseline, MetS components, body composition and exercise responses were similar between groups (all P > 0.05). After 16 weeks of intervention, only EXER reduced body weight, waist circumference (-1.21 ± 0.22 kg and -2.7 ± 0.3 cm; P < 0.001), mean arterial blood pressure and hence the composite MetS Z-score (-7.06 ± 0.77 mmHg and -0.21 ± 0.03 SD; P < 0.001). In the EXER group, CRF increased by 16% (0.302 ± 0.026, 95% CI 0.346 to 0.259 LO₂·min^-1; P < 0.001) but was not a significant predictor of MetS Z-score improvements (r = -0.231; β = -0.024; P = 0.788). Instead, body weight reductions predicted 25% of MetS Z-score changes (r = 0.508; β = 0.360; P = 0.001).

Conclusions: In MetS individuals, the exercise-training increases in CRF are not predictive of the improvements in their health risk factors. Instead, body weight loss (<2%) was a significant contributor to the improved MetS Z-score and thus should be emphasized in exercise training programs. ClinicalTrials.gov identifier: NCT03019796.

Keywords: Cardiorespiratory fitness; Cardiovascular diseases; High-intensity interval training; Metabolic syndrome X; Risk factors.