HIIT Effects on Cardiometabolic Health

The primary aim of this randomized clinical trial is to compare the effects of three different HIIT protocols and a control group on cardiometabolic health in young adults with obesity. Participants will be randomly assigned to one of the following three groups, with each having varying work-to-rest ratios: 1) HIIT-A, 2) HIIT-B, 3) HIIT-C, and 4) control group. HIIT-A, HIIT-B, and HIIT-C groups will participate in six sessions of a running based HIIT program over a 2-week training period. Pre-clinical markers of cardiovascular disease, blood lipids and fasting glucose will be measured at the following three time points: baseline, post-intervention, and 2 weeks after the training cessation (i.e., measure for detraining effect). All measurements will be performed three days before the training program and three days after the intervention to avoid the effect of the last training session. Afterwards, the detraining test will be measured 2 weeks post intervention.

Introduction: High-intensity interval training (HIIT) compared with other traditional exercise regimens has shown to be effective in improving cardiometabolic health (as measured by lipids, blood pressure \[BP\], insulin sensitivity, pulse wave velocity) in overweight and obese adults. By knowing which HIIT protocol is more efficacious in improving markers of cardiometabolic disease, exercise physiologists, researchers and clinicians can properly prescribe exercise medicine to obese young adults and possibly prevent disease progression. Therefore, the primary aim of the present research is to compare the effects of 3 different HIIT protocols compared with a control group on cardiometabolic health improvement in young adults with obesity.

Participants: Participants will be randomly assigned to one of the following three groups : 1) HIIT-A (5:25 s; 1:5 ratio), 2) HIIT-B (10:50 s; 1:5 ratio), 3) HIIT-C (20:100 s; 1:5 ratio), and 4) control group. HIIT-A, HIIT-B, and HIIT-C groups will participate in six sessions of running-based HIIT programs over a 2-week training period. The variables will be measured at the following three time points: baseline, post-intervention, and 2 weeks after the TC (i.e., measure for detraining effect).

High-Intensity Interval Training (six sessions over 2 weeks): Heart rate will be recorded - while performing a sprint running based on the wood court. The HIIT intensity will be set at 90% of the fastest baseline with 40 repetitions of 5-seconds work time, 20 repetitions of 10-seconds work time, or 10 repetitions of 20-seconds work time. All participants will perform one bout of sprint running for 5-, 10-, or 20- seconds followed by 25-second, 50-second, or 100-seconds resting. The supervisor will verbally encourage the running to inspire the sprint at "all-out" intensity. Note that a total of 200-seconds workout time is required per session.

Eligibility Criteria:
Inclusion Criteria:

* Young adults with obesity (Age 18 to 25 years old, BMI ≥ 30 kg/m2).

Exclusion Criteria:

* Syndromic obesity; 1) Any clinical symptoms including cognitive delay, 2) abnormalities in body structure(s), 3) organ-specific abnormalities (kidney, liver failure, excessive eating, and/or other signs of hypothalamic dysfunction such as fatigue, weakness and/or lack of interest in activities.
* Taking weight loss medication(s)
* Currently enrolled (or within previous 6 months) in a weight loss program;
* An underlying disease/medications (steroids, second generation psychotropic agents, hormonal contraception, statins, antihypertensive and antidiabetic medications) that could influence carbohydrate or lipid metabolism.
* Presence of cardiac pacemaker.
* Current or anticipated participation in another research that would interfere with any of the outcomes.
* Current or anticipated pregnancy.