CrossFit is a controversial but increasingly popular way of doing fitness, in which certified trainers get their pupils, in groups, to do exercises from weight lifting, athletics and gymnastics as fast and intensively as possible. The speed with which things are done makes CrossFit ideal for all those thousands of people who want to take up some form of exercise, but often don’t get round to it, you’d think. Sports scientists at Kansas State University have come to a different conclusion.
Study set up
The researchers performed experiments with two groups of about 10 women. The women were all in their twenties and overweight: they had an average BMI of 31.1. The researchers got the women to train for three times a week for 8 weeks.
One group trained in the traditional way [ART]. Three times a week they did a 50-minute session of moderate aerobic exercise, and twice a week they added on a full-body strength training session that lasted 20 minutes.
The other group did CrossFit three times a week [HIFT]. These training sessions consisted of a 15-minute warm up, a period of instruction and workout, and a 5-minute cool down. The workout lasted between 5 and 30 minutes.
Neither effect had any effect on the women’s BMI, lean body mass or fat mass. So they didn’t build up any muscle mass, nor did they lose any fat. The intensity of the training in both groups was probably insufficient to make any improvements to body composition.
The researchers did notice an effect on enjoyment of the training sessions. The women in the CrossFit group enjoyed their training sessions more than the women who trained in the traditional way, right from the start, as you can see in the figure below.
The longer they had been attending the traditional training sessions, the more enjoyment the women in this group experienced. Because the enjoyment of training in the CrossFit group remained at more or less the same level, the women in the traditional group, if the experiment had lasted longer, would probably have ended up enjoying doing fitness almost as much as the women in the CrossFit group.
The women in the traditional fitness group spent an average of 63.3 minutes on each workout. The amount of time it took the CrossFit group to do a session was only 13.3 minutes [No sir! We did not make a typo…] – and that’s probably not enough to increase fitness. For this reason CrossFit is not the most optimal fitness method for inactive people seeking to make a lifestyle change, the researchers conclude.
“It may be helpful for adults with lower exercise enjoyment to initiate moderate-intensity aerobic and resistance training when beginning a new exercise program, as significant improvements in exercise enjoyment can occur”, they write.
High-intensity compared to moderate-intensity training for exercise initiation, enjoyment, adherence, and intentions: an intervention study.
Understanding exercise participation for overweight and obese adults is critical for preventing comorbid conditions. Group-based high-intensity functional training (HIFT) provides time-efficient aerobic and resistance exercise at self-selected intensity levels which can increase adherence; behavioral responses to HIFT are unknown. This study examined effects of HIFT as compared to moderate-intensity aerobic and resistance training (ART) on exercise initiation, enjoyment, adherence, and intentions.
A stratified, randomized two-group pre-test posttest intervention was conducted for eight weeks in 2012 with analysis in 2013. Participants (n = 23) were stratified by median age (< or ? 28) and body mass index (BMI; < or ? 30.5). Participants were physically inactive with an average BMI of 31.1 ± 3.5 kg/m2, body fat percentage of 42.0 ± 7.4%, weight of 89.5 ± 14.2 kg, and ages 26.8 ± 5.9 years. Most participants were white, college educated, female, and married/engaged. Both groups completed 3 training sessions per week. The ART group completed 50 minutes of moderate aerobic exercise each session and full-body resistance training on two sessions per week. The HIFT group completed 60-minute sessions of CrossFit™ with actual workouts ranging from 5-30 minutes. Participants completed baseline and posttest questionnaires indicating reasons for exercise initiation (baseline), exercise enjoyment, and exercise intentions (posttest). Adherence was defined as completing 90% of exercise sessions. Daily workout times were recorded.
Participants provided mostly intrinsic reasons for exercise initiation. Eighteen participants adhered (ART = 9, 81.8%; HIFT = 9, 75%). HIFT dropouts (p = .012) and ART participants (p = .009) reported lower baseline exercise enjoyment than HIFT participants, although ART participants improved enjoyment at posttest (p = .005). More HIFT participants planned to continue the same exercise than ART participants (p = .002). No significant changes in BMI or body composition were found. Workouts were shorter for HIFT than ART (p < .001).
HIFT participants spent significantly less time exercising per week, yet were able to maintain exercise enjoyment and were more likely to intend to continue. High-intensity exercise options should be included in public health interventions.
PMID: 25086646 [PubMed – in process] PMCID: PMC4129110