CrossFit Exercise to Improve Glucose Control for Overweight and Obese Adults

Study Overview
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Brief Summary
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The purpose of this study was to examine the differences in glucose control, fitness, and body composition between a standard aerobic and resistance exercise training program and a shorter-duration, high-intensity CrossFit training program in overweight and obese physically inactive adults. Hypotheses: Both groups would improve glucose control, with the CrossFit group improving significantly more than the aerobic and resistance training group. Both groups would improve fitness, with the CrossFit group improving significantly more than the aerobic and resistance training group. Both groups would demonstrate decreases in body fat percentage and fat mass and increases in lean body mass, with the CrossFit group improving significantly more than the aerobic and resistance training group.

Detailed Description
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Overweight or obese participants will take part in an 8-week exercise intervention after clearance from a doctor, that is expected to improve glucose control, fitness (Eurofit and peak aerobic capacity), and body composition (body fat percentage, fat mass, and lean body mass). After stratification by age and body mass index, participants will be randomized to either a standard aerobic and resistance training exercise program or a relatively higher intensity, shorter duration CrossFit exercise program.

Official Title
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The Influence of a CrossFit Exercise Program on Glucose Control in Overweight and Obese Individuals

Conditions
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Hyperglycemia

Intervention / Treatment
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* Other: High-Intensity Functional Training
* Other: Aerobic and Resistance Training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: body mass index (BMI) of 25 - < 40, physically inactive (i.e., not participating in any structured exercise programs for the past 2 months and not exceeding 30 total minutes of physical activity per week) Exclusion Criteria: current smoker, pregnant, taking blood glucose altering medications, heart disease, type 1 or 2 diabetes mellitus, total cholesterol 200 mg/dL or higher

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Aerobic and Resistance Training<br>Participants completed 24 exercise sessions based on current guidelines. Aerobic exercise (50 min) was performed on machines every session and resistance training (20 min) was performed on machines two sessions per week. Aerobic intensity was prescribed at 40-50% of heart rate reserve (HRR) Weeks 1-4 and 50-60% HRR Weeks 5-8. Resistance training was supervised by an ACE certified personal trainer. One-repetition maximums (1-RM) were assessed Week 1 (i.e., seated bicep curl, military press, seated lat pulldown, seated leg extension, triceps pulldown, bench press, reverse leg curl, seated leg press). For Weeks 2-3 participants completed, 3 sets of 15 reps at 50% 1-RM; Weeks 4-5, 3 sets of 12 reps at 60% 1-RM; Weeks 6-7, 3 sets of 10 reps at 70% 1-RM; Week 8, 3 sets of 8 reps at 75% 1-RM. Three sets of 15 unweighted crunches were completed each day. One minute of rest was taken between each set and each exercise. | Other: Aerobic and Resistance Training<br>* The protocol was based upon current guidelines of 150 minutes moderate-intensity aerobic activity and 2 days of muscle strengthening per week.<br>|
| Experimental: High-intensity functional training<br>Participants completed a total of 24 sessions that were pre-programmed and led by a certified instructor (CrossFit Level 2), which lasted up to 60 minutes in duration. The first two class periods were structured as an introduction to common movements used in high-intensity functional training (HIFT; e.g., squats, deadlift, press, jerks, barbell, dumbbell, and medicine ball cleans, pullups, kettlebell swings, among others). No scheduled workouts were given on days 1 and 2. Beginning on day 3 each HIFT class consisted of 10-15 minutes of stretching and warmup, 10-20 minutes of instruction and practicing techniques and movements, and 5-30 minutes for the workout of the day, performed at vigorous intensity, relative to each person's ability and fitness level. All weights and movements were individually prescribed and recorded for each participant. | Other: High-Intensity Functional Training<br>* Participants were instructed to work as hard as they could while maintaining safe technique and proper form to achieve as many reps or rounds as possible in the prescribed time frame. As HIFT participants became accustomed to specific movements, less time was dedicated to practicing movements and technique.<br>* Other names: CrossFit;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in glucose control. | Fasting plasma glucose levels were taken after an overnight fast of at least 8 hours. An oral glucose tolerance test was conducted after ingestion of a 75g oral dextrose solution with finger sticks at 30, 45, and 60 minutes from time 0. The following equation was used to calculate glucose area under the curve which was the metric utilized to ascertain changes in glucose control: [(Time 45 - Time 30) * ½ (OGTT 30 + OGTT 45)] + [(Time 60 - Time 45) * ½ (OGTT 60 + OGTT 45)] | Baseline, Week 10 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in peak aerobic capacity | Modified Balke protocol | Baseline, Week 10 | 
| Change from baseline in sit and reach | Eurofit protocol for sit and reach distance using flex tester box | Baseline, Week 10 | 
| Change from baseline in standing broad jump | Eurofit protocol | Baseline, Week 10 | 
| Change from baseline in vertical jump | Eurofit protocol | Baseline, Week 10 | 
| Change from baseline in pushups | Eurofit protocol; completed on feet or knees | Baseline, Week 10 | 
| Change from baseline in situps | Eurofit protocol | Baseline, Week 10 | 
| Change from baseline in 40 meter dash | A handheld stopwatch was used to record time from the command Go until the participant crossed the line at 40 meters | Baseline, Week 10 | 
| Change from baseline in stork balance test |  | Baseline, Week 10 | 
| Change from baseline in body composition | Dual X-ray absorptiometry scan was used to assess body fat percentage, lean body mass, and fat mass. | Baseline, Week 12 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Exercise, Physical Fitness, Body Composition, Beneficial