CrossFit Exercise to Improve Glucose Control for Overweight and Obese Adults

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

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:

1. Both groups would improve glucose control, with the CrossFit group improving significantly more than the aerobic and resistance training group.
2. Both groups would improve fitness, with the CrossFit group improving significantly more than the aerobic and resistance training group.
3. 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.

Study Overview

• Status: Completed
• Conditions: Hyperglycemia
• Intervention / Treatment: Other: Aerobic and Resistance Training; Other: High-Intensity Functional Training

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 23
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Kansas
    • Manhattan, Kansas, United States, 66506
      • Kansas State University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Aerobic and Resistance Training; 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; The protocol was based upon current guidelines of 150 minutes moderate-intensity aerobic activity and 2 days of muscle strengthening per week.
Experimental: High-intensity functional training; 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; 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.; Other Names: CrossFit

What is the study measuring?

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

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time spent completing daily workouts	Time spent to complete each assigned daily workout was individually recorded for each participant	24 exercise sessions over 8 weeks

Collaborators and Investigators

• Sponsor: Kansas State University
• Investigators: Principal Investigator: Katie M Heinrich, PhD, Kansas State University; Study Director: Pratik Patel, MS, RD, Kansas State University

Publications and helpful links

General Publications

• Heinrich KM, Patel PM, O'Neal JL, Heinrich BS. High-intensity compared to moderate-intensity training for exercise initiation, enjoyment, adherence, and intentions: an intervention study. BMC Public Health. 2014 Aug 3;14:789. doi: 10.1186/1471-2458-14-789.

Study record dates

Study Major Dates

• Study Start: February 1, 2012
• Primary Completion (Actual): May 1, 2012
• Study Completion (Actual): May 1, 2012

Study Registration Dates

• First Submitted: July 3, 2014
• First Submitted That Met QC Criteria: July 9, 2014
• First Posted (Estimate): July 10, 2014

Study Record Updates

• Last Update Posted (Estimate): March 31, 2015
• Last Update Submitted That Met QC Criteria: March 30, 2015
• Last Verified: March 1, 2015

More Information

Terms related to this study

• Keywords: Exercise; Physical Fitness; Body Composition, Beneficial
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Body Weight; Hyperglycemia; Overweight
• Other Study ID Numbers: #6058