CROSSFIT-BASED HIGH-INTENSITY POWER TRAINING IMPROVES MAXIMAL AEROBIC FITNESS AND BODY COMPOSITION MICHAEL M. SMITH, ALLAN J. SOMMER, BROOKE E. STARKOFF, AND STEVEN T. DEVOR Health and Exercise Science, The Ohio State University, Columbus, Ohio ABSTRACT Smith, MM, Sommer, AJ, Starkoff, BE, and Devor, ST. Crossfitbased high-intensity power training improves maximal aerobic fitness and body composition. J Strength Cond Res 27(11): 3159–3172, 2013—The purpose of this study was to examine the effects of a crossfit-based high-intensity power training (HIPT) program on aerobic fitness and body composition. Healthy subjects of both genders (23 men, 20 women) spanning all levels of aerobic fitness and body composition completed 10 weeks of HIPT consisting of lifts such as the squat, deadlift, clean, snatch, and overhead press performed as quickly as possible. Additionally, this crossfit-based HIPT program included skill work for the improvement of traditional Olympic lifts and selected gymnastic exercises. Body fat percentage was estimated using whole-body _ O2max) was plethysmography, and maximal aerobic capacity (V measured by analyzing expired gasses during a Bruce protocol maximal graded treadmill test. These variables were measured again after 10 weeks of training and compared for significant changes using a paired t-test. Results showed significant (p , _ O2max in men (43.10 6 1.40 to 48.96 6 0.05) improvements of V 21 21 1.42 ml$kg $min ) and women (35.98 6 1.60 to 40.22 6 1.62 ml$kg21$min21) and decreased body fat percentage in men (22.2 6 1.3 to 18.0 6 1.3) and women (26.6 6 2.0 to 23.2 6 2.0). These improvements were significant across all levels of initial fitness. Significant correlations between absolute oxygen consumption and oxygen consumption relative to body weight was found in both men (r = 0.83, p , 0.001) and women (r = 0.94, p _ O2max scaled to body , 0.001), indicating that HIPT improved V weight independent of changes to body composition. Our data _ O2max and body composhow that HIPT significantly improves V sition in subjects of both genders across all levels of fitness. KEY WORDS interval training, aerobic fitness, body composition, crossfit, power training Address correspondence to Dr. Steven T. Devor, devor.3@osu.edu. 27(11)/3159–3172 Journal of Strength and Conditioning Research Ó 2013 National Strength and Conditioning Association INTRODUCTION H igh-intensity interval training (HIIT) has been used as an alternative to traditional endurance training for the improvement of aerobic fitness. HIIT is practical for many individuals due to the minimal time commitment required when compared to traditional continuous endurance training. A relatively new variation of HIIT has recently become popular and incorporates high-intensity resistance training using varied, multiple-joint movements. This high-intensity power training (HIPT) may also offer improvement of aerobic fitness with minimal time commitment compared with traditional aerobic training. HIPT has recently become popular worldwide; however, proponents have made many unsubstantiated claims. HIPT differs from traditional HIIT in that it includes a lack of a prescribed rest period, focus on sustained high power output and use of multiple joint movements. This crossfit-based, HIPT program uses named “workouts of the day” (WOD) in varied time domains. HIPT incorporates functional lifts such as the squat, deadlift, clean, snatch, and overhead press. Additionally, HIPT commonly uses basic gymnastic exercises using rings, hand-stands, and parallel bars. Some workouts are performed for a best time, and others are performed in the “as many rounds as possible” (AMRAP) style using varying time domains, ranging from 10 to 20 minutes. For example, a popular WOD uses 3 sets of 21, 15, and 9 repetitions of barbell front squats with an overhead press, immediately followed by body weight pull-ups. This WOD is performed with the goal of completing the exercises as quickly as possible. In summary, a HIPT training session will often include a random selection of multiple joint exercises and train participants to complete these movements at high resistance as quickly as possible. The sustained high power output associated with HIPT might serve as a stimulus for positive adaptations of maximal aerobic capacity (V_ O2max) and body composition. Although HIIT has been shown to improve body composition (13) and V_ O2max (14) in healthy adults, it is not clear if HIPT could offer these same benefits. To date, there have been no published investigations documenting changes to V_ O2max or body composition in response to this VOLUME 27 NUMBER 11 NOVEMBER 2013 3159 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Crossfit Training Improves Aerobic Fitness and Body Composition Figure 1. Representative sample of high-intensity power training protocol. AMRAP = as many rounds as possible; double-unders = 2 jump rope passes per jump; HS = hand stand; HSPU = hand stand push-up; HSW = hand stand walk; KB = kettlebell. Percentages listed as relative to participants’ 1-repetition maximum. style of training. Therefore, our aim was to determine if an HIPT training regimen could yield significant improvements to V_ O2max and body composition in healthy adults. To achieve our aim, we measured maximal aerobic capacity using a Bruce protocol graded exercise test and body composition with whole-body plethysmography in healthy adult 3160 the volunteers before and after a common HIPT training program. We tested the hypothesis that a 10-week HIPT regimen would improve V_ O2max and body composition in healthy adult volunteers. Furthermore, we hypothesized that improvements of V_ O2max and body composition would be found across all levels of initial aerobic fitness and body TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research www.nsca.com TABLE 1. Complete WOD list for 10 weeks of HIPT training.* Date Week 1 1/9/2012 Strength/skill WOD Back squat, 3 3 5 For best time: 5 @ 65% 1RM 5 @ 75% 1RM 5 @ 85% 1RM 50 Air squat 3 Flight stairs 100 Double under jump rope 25 Burpees 50 Double under jump rope 25 Burpees 100 Double under jump rope 3 Flight stairs 50 Air squat AMRAP 12 min: 7 Pull-ups Assist pull-up 5 @ 65% 1RM 5 @ 75% 1RM 5 @ 85% 1RM 1/10/2012 10-min “double unders” 10-min HSW/HSPU/HS 1-mile Run for best time 1/11/2012 1/12/2012 Deadlift 14 Front squat 21 Push-ups with release For best time: 5 @ 65% 1RM 30 Clean and jerk 5 @ 75% 1RM 5 @ 85% 1RM Ring work 10 min 21 Kettle bell swings Pull-ups and dips 1/13/2012 Back squat 5 @ 65% 1RM 21 Ring dips 15 Kettle bell swing 15 Ring dips 9 Kettle bell swings 9 Ring dips 3 Rounds for time: 5 Wide grip deadlift/high pull 5 @ 75% 1RM 5 @ 85% 1RM Assist pull-ups 5 @ 65% 1RM 5 @ 75% 1RM 5 @ 85% 1RM 5 Squat press 5 Pull-ups Week 2 1/16/2012 Thrusters 5 @ 85% 1RM 1/17/2012 10-min HSW/HSPU/HS “Fran” for best time: 21 Thrusters 21 Pull-ups 15 Thrusters 15 Pull-ups 9 Thrusters AMRAP 12 min: 7 Pull-ups 14 Front squats Notes 95 lbs For men, 65 lbs for women for thrusters 15:00 Time limit HS; for novices HSPU; for intermediates HSW; for advanced As many 3RM as possible in 20 min 135 lbs For male, 95 lbs female 70-lb Kettle bell for men, 53-lb kettle bell for women 135 lbs For men, 95 lbs women HS for novices, HSPU for intermediate, HSW for advanced 95 lbs For men, 65 lbs for women for squats VOLUME 27 NUMBER 11 NOVEMBER 2013 3161 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Crossfit Training Improves Aerobic Fitness and Body Composition 1/18/2012 Deadlift, 3 3 5 1/19/2012 5 @ 65% 1RM 5 @ 75% 1RM 5 @ 85% 1RM Overhead press, 3 3 5 5 @ 65% 1RM 5 @ 75% 1RM 5 @ 85% 1RM 10-min Muscle up practice 21 Push-ups with release 30 High hang power clean and jerks “Angie” in reverse, for time: 10-min Pistol squat practice 1/20/2012 Week 3 1/23/2012 1/24/2012 1/25/2012 1/26/2012 1/27/2012 3162 the Back squat, 3 3 5 5 @ 65% 1RM 100 Body weight air squats 100 Sit-ups 100 Push-ups 100 Pull-ups 3 Rounds, 1-min rest between rounds: 5 Reps Sumo deadlift high pull 5 @ 75% 1RM 5 Reps thruster 5 @ 85% 1RM Weighted pull-up 5 @ 65% 1RM 5 @ 75% 1RM 5 @ 85% 1RM 5 Pull-ups Deadlift, 3 sets 3 3 reps 3 @ 70% 1RM AMRAP, 20 min 10 High hang power cleans 3 @ 80% 1RM 3 @ 90% 1RM Overhead press, 3 sets 3 3 reps 3 @ 70% 1RM 3 @ 80% 1RM 3 @ 90% 1RM Advanced: muscle ups 4 Sets of 1RM 10 Toe to bar 10 Burpees Beginner: ring push-ups 4 Sets of 1RM Back squat, 3 sets 3 3 reps 3 @ 70% 1RM 3 @ 80% 1RM 3 @ 90% 1RM Pull-ups 5 @ 70% 1RM 135 lbs For men, 95 lbs for women 20-min Max time limit 135 lbs For male, 95 lbs for female 135 lbs For male, 95 lbs for female 60% of 1RM for power cleans 3 Rounds for time: 400-m Run 15 Pull-ups 30 Side lunges w/dowel overhead 3 Rounds for time: 20 Back squats 3 @ 80% 1RM 3 @ 90% 1RM 10-min Practice snatch form 21 Reps high hang power snatch 10-min HSW/HSPU/HS 21 Reps wall ball Hang power clean, 3 sets 3 3 reps 15 Reps high hang power snatch 15 Reps wall ball 9 Reps high hang power snatch 9 Reps wall ball 30 Double unders 135 lbs For men, 95 lbs for women 6 Flights of stairs 95 lbs For men, 65 lbs for women 10’ Distance from wall, 20 lbs for men, 14 lbs for women TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research Week 4 1/30/2012 1/31/2012 3 @ 70% 1RM 21 Deadlift 3 @ 80% 1RM 21 Box jumps 3 @ 90% 1RM Push press, 3 sets 5 @ 70% 1RM 3 @ 80% 1RM 3 @ 90% 1RM 30 Double unders 15 Deadlifts 15 Box jumps 30 Double unders 9 Deadlifts 9 Box jumps 3 Sets back squat Every 30 s until fatigue: 5 @ 75% 1RM 3 @ 85% 1RM 1 @ 95% 1RM Pull-ups 5 @ 75% 1RM 3 @ 85% 1RM 1 @ 95% 1RM Rest 1 Power clean 1 High hang power clean 1 Push jerk For time: 50 Double unders 50 Sit-ups 40 Double unders 40 Sit-ups 30 Double unders 30 Sit-ups 20 Double unders 20 Sit-ups 10 Double unders 10 Sit-ups 20 Double unders 20 Sit-ups 30 Double unders 30 Sit-ups 40 Double unders 40 Sit-ups 50 Double unders 50 Sit-ups 5 Rounds for best time: 2/1/2012 3 Sets deadlift 12 Deadlifts 9 High hang power clean 6 Push jerk 2/2/2012 5 @ 75% 1RM 3 @ 85% 1RM 1 @ 95% 1RM 3 Sets overhead press 5 @ 75% 1RM 3 @ 85% 1RM 1 @ 95% 1RM Gymnastics ring work: Toes to rings Lever hang 1,000-m Run 50 Kettle bell swings 1 Round for time: www.nsca.com 185 lbs For men, 115 lbs for women 24” For men, 20” for women 185 lbs For men, 115 lbs for women For novice: substitute burpee for double unders 155 lbs For men, 95 lbs for women Ring work done for form and at the skill level of each individual 53-lb Kettle bell for women, 35-lb Kettle bell for men VOLUME 27 NUMBER 11 NOVEMBER 2013 3163 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Crossfit Training Improves Aerobic Fitness and Body Composition 2/3/2012 Lever pull-up Muscle up Dip Lever sit Forward roll Back lever 3 Sets front squat 5 @ 75% 1RM 100 Body weight squats 3 @ 85% 1RM 1 @ 95% 1RM 15’ Rope climb 9 Reps front squat 15’ Rope climb 8 Reps front squat 15’ Rope climb 7 Reps front squat 15’ Rope climb 6 Reps front squat 15’ Rope climb 5 Reps front squat For best time: 10 Reps front squat 3 Sets pull-up 5 @ 75% 1RM 3 @ 85% 1RM 1 @ 95% 1RM Week 5 2/6/2012 Snatch technique practice 10 min (no load or rep requirement) 2/7/2012 Turkish getup technique practice 10 min (no load or rep requirement) 2/9/2012 12 Chest to bar pull up Jerk technique practice 10 min (no load or rep requirement) 12 Box jumps 9 Chest to bar pull-up 9 Box jumps 6 Chest to bar pull-ups 6 Box jumps For best time: 21 Squat cleans Muscle up technique practice 10 min 21 Push-up with release 15 Squat cleans 15 Push-up with release 9 Squat cleans 9 Push-up with release For best time: (no load or rep requirement) 5 Muscle ups Pull-up technique practice 10 min (no load or rep requirement) 2/8/2012 3 Rounds for best time: 15 Reps deadlift @ 60% of 1RM 15 Knees to elbows 2 Rounds for best time: 30 Kettle bell swings 4 Muscle ups 25 Kettle bell swings 2/10/2012 3164 the Overheat squat technique 10 min (no load or rep requirement) 135 lbs For men, 95 lbs for women Assist bands used for novice 24” Box for men, 20” box for women 95 lbs For men, 65 lbs for women As little assistance as possible given during muscle ups Novice men: 53-lb kettle bells Advanced men: 70lb kettle bells Novice women: 35lb kettle bells Advance women: 53-lb kettle bells 3 Muscle ups 20 Kettle bell swings 2 Muscle ups 15 Kettle bell swings 1 Muscle up 10 Kettle bell swings 3 Rounds for best time: 30 Double unders TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research 10 Overhead squats 10 HSPU www.nsca.com 95 lbs For men, 65 lbs for women HS/HSW for novice and intermediates 1 Flight of stairs Week 6 2/13/2012 3 Sets of back squats 5 Reps @ 75% 1RM 2/14/2012 Rest 2/15/2012 3 Sets power clean 5 Reps @ 75% 1RM Rest 3 Sets overhead squat 5 Reps @ 75% 1RM 2/16/2012 2/17/2012 Week 7 2/20/2012 2/21/2012 5 Sets back squat 5 Reps @ 65% 1RM 7 Sets deadlift 2 Reps @ 60% 1RM 8 Rounds for max reps: 20-s Deadlift 1RM 10-s Rest 20-s HSPU 10-s Rest AMRAP in 20 min 3 Burpees 5 Pull-ups Rest Rest Rest AMRAP in 20 min 5 Pull-ups 10 Body weight squat 20 Double unders AMRAP in 10 min 4 HSPU 8 Deadlifts 16 Kettle bell swings 2/22/2012 2/23/2012 7 Sets bench press 3 Reps @ 75% 1RM Power clean practice, 15 min 135 lbs For male, 95 lbs female 4 Rounds for best time: 30 Split jumps 10 Squat press 20 Push-ups 18-min AMRAP: 15 Box jumps 12 Overhead presses 2/24/2012 Week 8 2/27/2012 3 Sets front squats 5 Reps @ 65% 1RM 3 Reps @ 75% 1RM 1 Rep @ 85% 1RM 3 Sets back squats 5 Reps @ 65% 1RM 3 Reps @ 75% 1RM 1 Rep @ 85% 1RM HS substituted for novice 225 lbs For men, 135 lbs for women 53 lb Kettle bell for men, 35 lb kettle bell for women 95 lbs For men, 65 lbs for women 24” Box for men, 20” box for women 115 lbs For men, 75 lbs for women 9 Toes to bar 5 Rounds for best time: 20 Pull-ups 30 Push-ups 40 Sit-ups 50 Body weight squats 30-min Rest between rounds For best time: 15 Thrusters 15 Pull-ups 12 Thrusters 12 Pull-ups 9 Thrusters 9 Pull-ups 12 Thrusters VOLUME 27 NUMBER 11 NOVEMBER 2013 3165 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Crossfit Training Improves Aerobic Fitness and Body Composition 2/28/2012 2/29/2012 Pistol and HSPU drills: HSW 12 Pull-ups 15 Thrusters 15 Pull-ups AMRAP 15 min: 9 Deadlifts Parallettes DB presses 12 Push-ups with release 15 Box jumps Wall walks Shoulder touches (no load or rep requirement) 3 Sets, 5 reps bench press for form 5 Rounds for time: 15’ Rope climb 10 Wall ball 15 Toes to bar 20 Kettle bell swings 3/1/2012 10-min Power snatch practice 3/2/2012 3 Sets front squat 5 Reps @ 65% 1RM 3 Reps @ 75% 1RM 1 Rep @ 85% 1RM Week 9 3/5/2012 3/6/2012 10-min AMRAP 75/45-lb Snatch, 30 reps 135/75-lb Snatch, 30 reps 165/100-lb Snatch, 30 reps 210/120-lb Snatch, as many as possible 3/8/2012 Low bar back squat 5 Sets, 5 reps @ 65% 1RM HSPU practice, 10 min Deadlifts 7 sets, 2 reps @ 55% 1RM (work on form) AMRAP 20 min: 5 Pull-ups 10 Body weight squats 20 Double unders AMRAP 10 min 4 HSPU 8 Deadlifts Bench press 7 Sets, 3 reps @ 65% 1RM Not for time: 4 Rounds 30 Split jumps 10 Thrusters 20 Push-ups AMRAP 18 min: 15 Box jumps Rest 12 Push presses 3/9/2012 3166 the 24” Box for men, 20” box for women 10’ Distance from wall, 20 lbs for men, 14 lbs for women 53 lbs For men, 35 lbs for women Men/women Rest 16 Kettle bell swings 3/7/2012 155 lbs for men, 100 lbs for women HS for novice 225 lbs For men, 135 lbs women 53 lbs Men, 35 lbs women 95 lbs Men, 65 lbs women 24” Box for men, 20” box for women 115 lbs For men, 75 lbs women 9 Toes to bar For best time: 5 Rounds, 3-min rest between rounds 20 Pull-ups 30 Push-ups 40 Sit-ups Rest TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research www.nsca.com 50 Body weight squats Week 10 3/12/2012 3/13/2012 3/14/2012 Low bar back squat 3 Sets, 5 reps @ 50% 1RM 3 Sets, 5 reps @ 65% 3 Sets, 5 reps @ 75% 3 Sets, 5 reps @ 85% Bench press 3 Sets, 5 reps @ 50% 3 Sets, 5 reps @ 65% 3 Sets, 5 reps @ 75% 3 Sets, 5 reps @ 85% 1RM 1RM 1RM 1RM 1RM 1RM 1RM 15-min Power cleans Emphasis on form 3/15/2012 3/16/2012 Rest AMRAP 15 min: 3 Reps hang clean 3 Thrusters 3 Rope climbs 4 Rounds for best time: 5 Muscle ups 30 Double unders 10 Dips 7 Rounds for time: 10 Burpees 10 Clean high pulls AMRAP 12 min: 150 Wall ball 90 Double unders 30 Muscle ups 3 Rounds for time: 800-m Run 50 Romanian deadlifts Rest 115 lbs For men, 75 lbs for women Assist for novices 95 lbs For men, 65 lbs women 10 ft From wall, 20 lbs male, 14 lbs female Assist for novices 45 lbs For men, 45 lbs women 50 Sit-ups *AMRAP = as many rounds as possible; double-unders = 2 jump rope passes per jump; HS = hand stand; HSPU = hand stand push-up; HSW = hand stand walk; HIPT = high-intensity power training; KB = kettle bell; WOD = workouts of the day; RM = repetition maximum. composition, not only in the cohorts of the lowest initial values of these markers. adults. Body composition using air displacement plethysmography and maximal aerobic capacity using a Bruce treadmill graded exercise test were assessed in all the subjects in the METHODS morning (7:30–11:30 AM) over a 5-day period preceding the Experimental Approach to the Problem onset of training. Measurements were obtained after an overThis study investigated the effect of a 10-week, crossfit-based, night fast, and the subjects refrained from exercise, alcohol, HIPT program on body composition and V_ O2max in healthy and caffeine for the previous 24 hours. A total of 43 subjects completed the training program and returned for assessment of changes in the dependent variTABLE 2. Subject characteristics.*† ables of body composition and Men (n = 23) Women (n = 20) Range V_ O2max. All returning subjects were assessed at the same time Age (y) 33.9 6 1.6 31.2 6 1.3 21.0–48.0 of the day as the pretraining Height (in.) 70.6 6 0.6 64.8 6 0.6 60.0–77.0 measures over a 5-day period Weight (kg) 90.71 6 2.67 68.02 6 3.00 44.54–118.18 BMI (kg$m22) 28.1 6 0.6 25.1 6 1.1 19.1–37.4 after the completion of the Body fat (%) 22.2 6 1.3 26.6 6 2.0 10.7–46.1 program. Lean mass (kg) V_ O2max (L$min21) V_ O2max (ml$kg21$min21) 70.25 6 1.76 3.88 6 0.13 43.10 6 1.40 49.00 6 1.10 2.39 6 0.09 35.98 6 1.60 36.35–82.17 1.47–5.12 20.00–58.00 _ O2max = maximal oxygen con*BMI = body mass index; in. = inches; kg = kilograms; V sumption. †All data are resting values and are presented as mean 6 SEM. Subjects The participants of all levels of aerobic fitness and body composition were recruited from and trained at a Crossfit affiliate (Fit Club, Columbus, OH, VOLUME 27 NUMBER 11 NOVEMBER 2013 3167 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Crossfit Training Improves Aerobic Fitness and Body Composition TABLE 3. Adaptations in male subjects after the 10-week HIPT.*† Pretraining Weight (kg) BMI (kg$m22) Body fat (%) Lean mass (kg) V_ O2max (L$min21) V_ O2max (ml$kg21$min21) 90.71 28.1 22.2 70.25 3.88 43.10 6 6 6 6 6 6 2.67 0.6 1.3 1.76 0.13 1.40 Posttraining p 6 6 6 6 6 6 0.0008 0.0006 0.000002 0.001 0.001 0.000004 87.25 27.0 18.0 71.23 4.23 48.96 2.58 0.6 1.3 1.87 0.13 1.42 _ O2max = maximal oxygen consumption; HIPT = high-intensity *BMI = body mass index; V power training. †All data are resting values and are presented as mean 6 SEM. TABLE 4. Adaptations in female subjects after 10-week HIPT.*† Pretraining Weight (kg) BMI (kg$m22) Body fat (%) Lean mass (kg) V_ O2max (L$min21) V_ O2max (ml$kg21$min21) 68.02 25.1 26.6 49.00 2.39 35.98 6 6 6 6 6 6 3.00 1.1 2.0 1.1 0.09 1.60 Posttraining p 6 6 6 6 6 6 0.01 0.01 0.00008 0.01 0.005 0.0006 66.23 24.4 23.2 50.06 2.62 40.22 2.70 1.0 2.0 1.2 0.1 1.62 _ O2max = maximal oxygen consumption; HIPT = high-intensity *BMI = body mass index; V power training. †All data are resting values and are presented as mean 6 SEM. Figure 2. Maximal aerobic fitness and body composition improvements after a 10-week high-intensity power training intervention. After training, the V_ O2max increased and body fat percentage decreased significantly. *p , 0.05. 3168 the USA). Out of the original 54 participants, a total of 43 (23 men, 20 women) fully completed the training program and returned for follow-up testing. Of the 11 subjects who dropped out of the training program, 2 cited time concerns with the remaining 9 subjects (16% of total recruited subjects) citing overuse or injury for failing to complete the program and finish follow-up testing. The subjects had already been following a “Paleolithic” type of diet before and after completion of the training protocol. All the subjects provided written informed consent, and all study methods and protocols were approved in advance by the Institutional Review Board at The Ohio State University. Procedures Training Program. The subjects participated in a crossfit-based HIPT program using basic gymnastic skills (hand stands, ring, and bar exercises) and traditional multiple-joint, functional, resistance exercises (squat, press, deadlift, Olympic lifts) performed as quickly as possible at a high intensity (low repetition, high percentage of 1-repetition maximum). All training was performed at a CrossFit affiliate under the supervision of a fellow of the American College of Sports Medicine (ACSM) and an ACSM certified registered clinical exercise physiologist. The 10-week program was varied so that some exercises were performed for a best time, and others were performed in the AMRAP style in varying time domains ranging from 10 to 20 minutes. During the strength and skill portion of the exercise session, there was no prescribed recovery time, whereas during the WOD portion of the session, TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research www.nsca.com Measurements Instruments, Concord, CA, USA), which is shown to be an accurate method for assessing body composition in adults (2). Before measurement, the system was calibrated for volume using a cylinder of a known volume (50.1461 L) and for mass using two 10-kg weights. Fasting-state body weight was measured to the nearest 0.1 kg, and the subjects entered the Bod Pod chamber wearing only a tight fitting swimsuit and swim cap. Body volume measurements were taken in duplicate and repeated if measures were not within 150 ml of each other Figure 3. Changes in maximal relative aerobic fitness after a 10-week high-intensity power training intervention. When broken into quantiles of initial aerobic fitness scaled to body weight, a significant increase of the V_ O2max (7). Body density was calculated from baseline was observed in all groups. **p , 0.01; *p , 0.05. as mass/body volume and body fat percentage was calculated by using Siri’s formula (12). Body mass index was calculated as the subjects completed all the exercises as quickly as possible kilograms of body mass divided by height in meters squared. with no prescribed rest period. Two representative weeks of the training program are found in Figure 1. The subjects were Graded Exercise Testing. All the subjects performed a maximal asked to refrain from all other structured physical activity while treadmill exercise test before and after the training program participating in this study, and they complied with this request, _ O2max. The subusing the Bruce protocol (4) to determine V as verified by activity logs. A complete list of all exercises jects wore nose clips and breathed into a 1-way mouthpiece, performed over the 10 weeks is found in Table 1. which allowed expired gases to be collected in a mixing chamber. The volume of expired air, oxygen consumption, and carBody Composition. Percentage body fat was calculated using bon dioxide production were determined by gas analyzers and the Bod Pod air-displacement plethysmography device (Life a pneumotachometer attached to a calibrated, computerized metabolic cart (Parvomedics, Sandy, UT, USA), which provides accurate and reliable results compared with the Douglas bag method (6). Oxygen consumption values were calculated every 15 seconds, and the 2 highest consecutive values were averaged to determine absolute maximal oxygen consumption in liters per minute. Body weight was divided into absolute oxygen consumption to yield a value relative to body mass and is _ O2max reported as relative V in units of milliliters of O2$per kilogram of body Figure 4. Changes in maximal body composition after a 10-week high-intensity power training intervention. When mass$per minute. The test was broken into quantiles of initial body composition, a significant decrease from baseline was observed in all groups. **p , 0.01; *p , 0.05. terminated and considered maximal when subjects reached selfVOLUME 27 NUMBER 11 NOVEMBER 2013 3169 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Crossfit Training Improves Aerobic Fitness and Body Composition determined exhaustion, and was verified by the 2 of following criteria: (a) plateau in oxygen consumption despite an increase in workload, (b) respiratory exchange ratio .1.1, and (c) rating of perceived exertion of 18– 20. Using these parameters have previously shown to be a reliable _ O2max has method of verifying V been attained, and provides statistically indistinguishable measurements compared with supramaximal testing (8). Metabolic sensors were recalibrated between each exercise test. Statistical Analyses Figure 5. Changes in absolute maximal aerobic fitness after a 10-week high-intensity power training intervention. When broken into quantiles of initial absolute aerobic fitness, a significant increase of the V_ O2max from baseline was observed in the “Well-below avg, Below avg, and Above avg” groups. **p , 0.01; *p , 0.05. TABLE 5. Multivariate regression analysis model for DV_ O2max (ml$kg21$min21).* Gender b 6 SEM Variables D D D D Male Female Absolute V_ O2max (L$min21) Body fat (%) Absolute V_ O2max (L$min21) Body fat (%) 12.50 20.67 13.62 20.32 6 6 6 6 1.05 0.12 1.06 0.19 p R2 0.001 0.001 0.001 0.100 0.88 0.91 _ O2max and body fat against changes in *Model was built using changes of absolute V relative V_ O2max in both genders. TABLE 6. Correlation matrix for DV_ O2max (ml$kg21$min21).* Gender Variables DV_ O2max (ml$kg21$min21) Female DV_ O2max (ml$kg21$min21) Male D AbsV_ O2max (L$min21) DLM (kg) DBF (%) DWeight (kg) 0.83† 0.05 20.49z 20.24 0.94† 0.05 20.07 0.01 _ O2max = change in absolute V_ O2max from pretraining to posttraining values; *D AbsV DV_ O2max = change in relative V_ O2maxV_ O2max from pretraining to posttraining values; BF = body fat percentage; LM = lean mass. †p , 0.001. zp , 0.05. 3170 the Changes of V_ O2max and body composition from pretraining to posttraining were tested using a 2-tailed, paired t-test. These values were tested as an entire group, and also in subsets that were stratified by initial values of aerobic fitness and body composition, respectively. These subsets were based on normative data for the age and gender of each participant (3). Percentile rankings correspond to descriptors as follows: well above average (.90), above average (70–90), average (50– 70), below average (30–50), and well below average (10– 30). Two-tailed, paired t-tests were then used to test the differences between pretraining and posttraining values of V_ O2max and body composition. A forward stepwise multivariate linear regression was performed to identify significant predictors of relative V_ O2max. The model considered the following variables for inclusion: change in absolute V_ O2max and body fat. Additionally, a linear regression analysis was performed, and Pearson correlation coefficients were calculated to determine the contribution of changes in total body weight, TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research lean mass, and absolute oxygen consumption to the observed increase in relative V_ O2max. Data are reported as mean 6 SEM. Statistical analysis was performed using STATA (version 11.1, College Station, TX, USA). Statistical significance was defined a priori as the critical a-level of p # 0.05. RESULTS Characteristics of the subjects who volunteered for the study are presented in Table 2. The mean and SEM of the variables before and after training for male subjects are presented in Table 3, and female subjects in Table 4. After the training program, a significant increase in the relative V_ O2max and decrease in percent body fat were observed. These changes are presented in Figure 2. The differences in relative oxygen consumption and body composition were significant when broken into quantiles of “well-below average,” “below average,” “average,” “above average,” and “well-above average,” indicating improvement across all initial levels of fitness (Figures 3 and 4). _ O2max was found in the wellImprovement in the absolute V below average, below average, and above average groups (Fig_ O2max ure 5). A regression analysis revealed that the absolute V and body fat percentage were significant predictors of the _ O2max in men (p = 0.001), but only change in the relative V _ O2max in women _ O2max was a predictor of relative V absolute V (Table 5). Furthermore, the improvement of maximal relative aerobic capacity could be explained by an increase in absolute oxygen consumption in men (r = 0.83, p = 0.001) and women (r = 0.94, p = 0.001), and was further informed by the correlation of a decrease in body fat in men only (r = 0.49, p = 0.05). This correlation analysis is presented in Table 6. DISCUSSION The aim of this research was to examine the effects of a novel, crossfit-based HIPT program on aerobic fitness and body composition in healthy adults. The results presented here confirm our hypothesis that a 10-week crossfit-based HIPT program significantly improves the maximal aerobic capacity and body composition in individuals of all fitness levels and _ O2max was strongly genders. The improvement of the relative V mediated by improvement of absolute oxygen consumption in women, and by improvement of absolute oxygen consumption and decreased body fat in men. Although the HIIT has previously been shown to improve body composition (13) and _ O2max (14) in healthy adults, this is the first investigation V showing that similar benefits can be obtained using a crossfitbased HIPT program. After the HIPT training, body fat percentage dropped by 3.7%, across all individuals, in absolute terms. This reduction corresponds to a pretraining to posttraining change of 15.5%. As presented in Figure 4, there were significant declines in body fat percentage for all fitness cohorts. This finding also holds when comparing men and women. Tables 3 and 4 show the results for men and women, respectively. Absolute and percentage changes in body fat were similar for both genders. www.nsca.com These results indicate a positive role for HIPT in reducing body fat percentage in both genders across all levels of initial fitness. However, given the body composition changes that have been observed in response to a Paleolithic type diet (10), it is impossible to ascribe the entirety of the improvement in body composition in our subjects to HIPT training alone. The results for oxygen consumption again reveal that quantiles of all initial levels of fitness were improved in response to an HIPT training regimen. Oxygen consumption, as expressed relative to body weight, significantly increased across all groups (Figure 3). Again, men and women attained similar improvements in relative V_ O2max, 13.6 and 11.8%, respectively (Tables 3 and 4). As commonly understood, improvement of relative V_ O2max can result from increased absolute oxygen consumption, decreased body weight, or changes in both. Our data indicate that improvement of absolute oxygen consumption is the primary factor in the improvement of relative V_ O2max, with a small contribution of the reduction of body fat percentage in men only. To our knowledge, this is the first report of improvement of relative and absolute V_ O2max in response to a crossfit-based HIPT training protocol. Combining the quantiles to represent men and women, Tables 3 and 4 show a significant increase of absolute V_ O2max for both genders. These findings show that aerobic benefits can be gained through HIPT, regardless of initial fitness or gender. Past HIIT training has revealed similar improvements in V_ O2max. Astorino et al. reported .6% increase in absolute V_ O2max and 5.5% increase in relative V_ O2max, whereas Trulik et al. reported a 13.4% increase in relative V_ O2max in response to HIIT. Our finding that improvement of V_ O2max in subjects who are stratified as well above average is at odds with previous work using an HIIT protocol that finds no improvement of V_ O2max (5). Even HIIT studies in well-trained subjects using hyperoxia have previously failed to find an improvement of oxygen consumption in the subjects of comparably high V_ O2max (9,11). Compared with HIIT, our results indicate a possible superior role for HIPT in the improvement of maximal aerobic capacity in well-trained subjects. Future studies are needed in this area. A unique concern with any high-intensity training program such as HIPT or other similar programs is the risk of overuse injury. Despite a deliberate periodization and supervision of our Crossfit-based training program by certified fitness professionals, a notable percentage of our subjects (16%) did not complete the training program and return for follow-up testing. Although peer-reviewed evidence of injury rates pertaining to high-intensity training programs is sparse, there are emerging reports of increased rates of musculoskeletal and metabolic injury in these programs (1). This may call into question the risk-benefit ratio for such extreme training programs, as the relatively small aerobic fitness and body composition improvements observed among individuals who are already considered to be “above VOLUME 27 NUMBER 11 NOVEMBER 2013 3171 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Crossfit Training Improves Aerobic Fitness and Body Composition average” and “well-above average” may not be worth the risk of injury and lost training time. Further work in this area is needed to explore how to best realize improvements to health without increasing risk above background levels associated with participation in any non–high intensity based fitness regimen. In conclusion, we can infer from our data that a crossfitbased HIPT training program can yield meaningful improvements of maximal aerobic capacity and body composition in men and women of all levels of fitness. The improvement of maximal oxygen consumption expressed as a function of body mass was significantly correlated to increased absolute oxygen consumption, indicating that HIPT can improve aerobic fitness independent of any concurrent weight loss. Although improvements in aerobic fitness are similar to those previously found in HIIT programs, the current HIPT program has demonstrated an increase of maximal oxygen consumption, even in subjects with well-above average V_ O2max. This increase in V_ O2max has not previously been documented in response to an HIIT program, indicating that HIPT may be a possible strategy for the improvement of aerobic fitness in athletes who are considered to be well-above average. Future research is needed to investigate these differences. PRACTICAL APPLICATIONS To our knowledge, no research on the aerobic benefits of HIPT has been conducted. HIPT focuses on high intensity resistance training using multiple joint exercises, with little to no focus on traditional aerobic activities. Despite this, our results show that this type of training also provides aerobic and body composition benefits. The increased aerobic capacity of the subjects in our HIPT study were similar to those found in past research (5,13). Based on the results presented here, individuals of all fitness levels and either gender can realize body composition and aerobic benefits from HIPT. Given that our subjects were following a Paleolithic diet, we cannot relate all of the observed weight loss to HIPT training. However, HIPT and Paleolithic diet in combination could be used to promote positive changes in body composition. Additionally, these findings could be significant for athletes wishing to improve their aerobic performance. Although an aerobic training regimen based is primarily on long slow endurance workouts, for example (cycling and running for extended periods at moderate intensity ,70% V_ O2max), we propose that HIPT training could be used as an adjunct to this strategy in light of our findings. Furthermore, HIPT workouts require much less time spent training than 3172 the traditional aerobic exercise and could serve as a convenient and practical addition to a training regimen focused on improvement of aerobic fitness or body composition in healthy adults. REFERENCES 1. Bergeron, MF, Nindl, BC, Deuster, PA, Baumgartner, N, Kane, SF, Kraemer, WJ, Sexauer, LR, Thompson, WR, and O’Connor, FG. Consortium for Health and Military Performance and American College of Sports Medicine consensus paper on extreme conditioning programs in military personnel. Curr Sports Med Rep 10: 383–389, 2011. 2. Biaggi, RR, Vollman, MW, Nies, MA, Brener, CE, Flakoll, PJ, Levenhagen, DK, Sun, M, Karabulut, Z, and Chen, KY. 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