Due to the high-profile CrossFit athlete injury, the American Council on Exercise (ACE) is promoting the results to their recent CrossFit study. In a phone interview on Jan. 30, ACE Chief Science Officer Cedric X. Bryant, Ph.D., FACSM, discussed with me the reasons for the ACE study, as well as how the results can help exercise consumers considering CrossFit and other High-Intensity Interval Training (HIIT) forms, can ensure the safest, and most beneficial workout.
“Performance based high intensity workouts such as CrossFit can generate increased fitness results, yet it is critical that individual ability levels and goals are taken into consideration,” comments Bryant. “In order to achieve the right benefits and avoid injury, as with most forms of exercise, it comes down to the quality of the instructor or coach in order to ensure workouts are appropriate and fulfilling individual needs.”
The CrossFit regimen combines a variety of functional movements at relatively high intensity. With the increased media attention and that high intensity workouts in general are in first place of ACSM's Top 20 Fitness Trends of 2014, ACE sponsored the CrossFit study as a means to offer the public an unbiased opinion regarding the physiological outcomes to such training.
Led by John Porcari, Ph.D., head of University of Wisconsin, LaCrosse’s Clinical Exercise Physiology program, 16 healthy, moderately to very fit current CrossFit females and males 20-47 years of age volunteered to participate. Participants completed initial maximum treadmill tests to determine VO2max and ratings of perceived exertion (RPE) in order to establish individual quantifiable fitness baselines.
Subjects participated in one of two separate CrossFit workouts that had been used as an official CrossFit Workout of the Day (WOD) with the goal to complete all prescribed exercise repetitions in the shortest amount of time. One WOD incorporated burpees, kettlebell swings, and box jumps, while the other included thrusters (a front squat into a push press with a barbell) and assisted pull-ups. During the workout, researchers recorded participant heart rate (HR), RPE was assessed after each round, and blood lactate concentration was tested at the beginning and upon completion of each CrossFit WOD.
The two workouts were completed in under 12 minutes, not including warm-up and cool-down, and an average of 115.8 calories/subject were burned. The data showed participants maintained a vigorous intensity well above their anaerobic and lactate thresholds, and the RPE values for both workouts were rated as “hard”. Based on the high intensity of the workouts tested, Pocari and his team concluded that CrossFit does a really good job of helping exercisers improve their aerobic fitness, while burning a fair number of calories in the process.
Yet, Porcari cautions: “People absolutely need to be properly screened before beginning CrossFit.”
Bryant agrees: “As with most forms of exercise the quality of instructor really matters. If you are considering CrossFit, look for a trainer that takes the time to do individual assessments, and takes a fitness history. They should also ask about any pre-existing conditions and/or limitations and be able to make exercise modifications based on participant need and ability.”
Bryant maintains that while HIIT is time efficient in calorie burning it is tempting to succumb to the idea that if ‘some is good more is better’ which can not only be dangerous, but can actually be counter- productive: “It is critical that the CrossFit Coach or trainer respects individual limits, and encourages adequate rest and recovery time. Positive adaptations (from high intensity exercise) are achieved during recovery periods, so it is critical to mix in recovery sessions into any high intensity training program in order to achieve maximum benefits.” For best results, Bryant recommends limiting HIIT trainings to twice per week as part of an overall comprehensive training program.
Bryant also warns of the reasonably strong psychological component to the CrossFit regimen. “The need to ‘belong’ in the social network of CrossFit could lead participants to ignore signs of over training in order to stay competitive with the group.” Bryant discussed future research will focus on the importance of intentional recovery in performance training as well as the physiological effects to long term CrossFit exercisers.
In summary, Bryant offers these 5 tips to help those CrossFit participants feel the burn, without bringing the pain:
- Take the introductory course offered by your CrossFit affiliate
- Know how to modify the movements to fit your fitness level
- Regularly communicate with your CrossFit Coach
- Respect your limits
- Avoid overtraining
Cedric X. Bryant, Ph.D., FACSM, is Chief Science Officer national and international lecturer, writer and expert source for American Council on Exercise and author of more than 250 articles or columns published in various fitness magazines, sports medicine and exercise science journals.