The Effects of High-intensity Aerobic Training in Patients With Metabolic Syndrome

Background. The prevalence of metabolic syndrome (MetS) has been increasing, and its risk is positively correlated with age. Due to ageing society in Taiwan, how to treat metabolic syndrome and decrease the complications is an important health issue. Relatively few studies have been focusing on the effects of exercise training in patients with MetS with long-term follow-up. Recently, high-intensity interval training or aerobic interval training (AIT) consisting of high intensity separated by active recovery has been proposed to be more effective than isocaloric continuous moderate-intensity exercise (CME) in raising exercise capacity (VO2max) in some specific patient population.

Purpose. The purposes are to (1) compare the effects of 16-week CME and AIT on reducing the numbers of metabolic risk factors in patients with MetS and the prevalence.

Hypothesis: 16-week AIT reduces more metabolic risk factors than CME in patients with MetS.

Methods. This study will be a multiple-center trial. One hundred and twenty patients, aged ≥45 years, with a diagnosis of MetS for each center will be recruited. Subjects will be randomly assigned to either control, CME, or AIT group after baseline assessments. Participants in control group will receive usual care and the others in two exercise groups will undergo 16-week exercise training. All subjects will receive 16-week, 6-month and 1-year follow-ups including blood test, body composition (body mass index, waist circumference), pulse wave velocity, and maximal exercise testing. Statistical analysis will be conducted using SPSS 11.5, p \< 0.05 indicating statistical significance. Data will be presented in mean±standard deviation or number (percentile) with intention-to-treat analysis. Chi-square test or one-way Analysis of Variance (ANOVA) will be used to compare whether there are between-group differences at baseline. Two-way repeated measures ANOVA and post-hoc test will be performed to examine time and group effect if there is interaction effect, otherwise Bonferroni will be used. The subgroup analysis between MetS and n-MetS after training will be performed using the same statistical methods.

Intervention (exercise) protocol:

1. CME group: exercise at least 30-minute moderate intensity 5 times a week, twice on treadmill under supervision and home exercise 3 times a week. CME protocol including 10-minute warm-up at 40% maximal heart rate (HRmax), 30-minute moderate intensity exercise at 50-70% HRmax and 5-minute cool-down at 40% HRmax
2. AIT group: exercise 3 times a week including twice on treadmill under supervision and home exercise once a week. AIT protocol including 10-minute warm-up and 5-minute cool-down at 40% HRmax, participants and exercise 4-minute high-intensity training at 85-90% HRmax and 4 times separated by 3-minute active recovery at 70% HRmax.

Eligibility Criteria:
Inclusion Criteria:

* 45-75 years old
* diagnosis of metabolic syndrome
* able to follow the instruction

Exclusion Criteria:

* unstable hypertension
* coronary artery disease or pulmonary diseases
* chronic kidney failure
* unable to perform exercise