Participants
Twenty-nine participants (n = 29, males = 13, females = 16; mean ± standard deviation; age: 31.87 ± 7.61 years; weight: 78.68 ± 16.45 kg;% body fat: 21.97 ± 9.02%) completed the six week randomized, open label study. All participants had been participating in at least three CrossFit workouts per week for at least six months. Participants were required to be apparently healthy (based on completed medical history questionnaires) and had not used dietary supplements that could influence physical performance or body composition in the past three months. Testing procedures were explained to all volunteers at the familiarization session. Participants completed medical and physical activity history questionnaires and read and signed Informed Consent statements (approved by the University IRB) prior to the start of the study.
Familiarization
Before beginning baseline testing, participants were required to attend a familiarization session. At the familiarization session, in addition to completing paperwork and signing the Informed Consent statements, participants completed a practice VO2MAX graded exercise test and Wingate power test to become familiar with testing protocols.
Testing
After attending the familiarization session, participants completed two Workouts of the Day (WOD1 and WOD2) at a CrossFit gym. WOD1 required the participant to complete a 500 m row, 40 wall balls, 30 push-ups, 20 box jumps, and 10 thrusters as quickly as possible. The time to completion was recorded in seconds. After a 20 minute rest, participants then completed WOD2 which consisted of an 800 m run "buy in" (only completed once) followed by as many rounds as possible (AMRAP) of 5 burpees, 10 Kettlebell swings, and 15 air squats within 15 minutes. At the end of WOD2, the number of completed repetitions was recorded. Participants again reported to the Human Performance Lab (HPL) to complete baseline (T1) testing (anthropometric, aerobic, and anaerobic) within 48 hours of completing WOD1 and WOD2. Participants repeated testing measures (T2; VO2MAX, Wingate, and body composition) 24 to 48 hours after completing both WODs at the end of the six-week supplementation period.
Height and weight were measured at T1 and T2 using the SECA 242 measuring instrument (242, SECA, Hanover, MD) and the TANITA Body Composition Analyzer (Model TBF-310, TANITA, Arlington Heights, IL), respectively. A Dual-Energy X-ray Absorptiometry scan (DEXA) was then completed using the Hologic Discovery (Hologic, Inc., Bedford, MA). Body fat percentage (%BF), fat mass (FM), and lean body mass (LBM) were recorded from the DEXA scan printout.
A maximal oxygen consumption running treadmill test (VO2MAX) was completed during the familiarization session and at T1 and T2 to determine aerobic capacity. Participants were fitted with a mouth piece and head apparatus then instructed to walk or run for as long as possible. The Bruce protocol was utilized, which provides the participant with a three minute warm-up followed by successive three minute stages that provide an increase in speed and incline. All expired air traveled through the mouth piece and into the TrueOne® 2400 (ParvoMedics, Sandy, UT) metabolic cart to be analyzed by the computer. The VO2MAX value in mL/kg/min was recorded after the completion of the test.
After 15 minutes of rest, the Wingate power test was used to analyze anaerobic capacity. Utilizing the Excalibur Sport V2 (LODE, Groningen, The Netherlands) bicycle, a Wingate protocol was followed. The participant was instructed to maintain RPMs at 60–80 throughout the two minute warm-up. Immediately before the 30-second test, the participant was told to pedal as hard and as fast as possible while remaining seated. For 30 seconds, the load placed on the fly-wheel remained constant [(0.7 N·kg-1 body mass) × (participant’s body mass (kg)]. Peak power (WPP) and mean power (WMP) were recorded in Watts.
All participants completed a four day (4-d) diet log (two week days, two weekend days) prior to T1 and T2. In addition, a one day (1-d) diet log was completed on the last workout day of each week throughout the supplementation period. Participants were asked to report all food and beverage intake (excluding water) by writing the name of the food, the method of preparation, and the quantity consumed. Diet logs were analyzed using the Food Processor (esha Research, Salem, OR) computer software and a four day average (T1 and T2) for total calories, protein, carbohydrate, and fat consumed were recorded.
Supplementation and training
Participants were matched based on sex and number of days they participated in CrossFit per week and then randomly assigned to either the supplement group (SUP) or the control group (CTL). SUP participants received a pre-workout supplement (19 g, Pursuit Rx Pre-Workout, Dymatize Nutrition, Dallas, TX) that was to be taken thirty minutes before each CrossFit workout. The pre-workout supplement contained Pomegranate Fruit Extract (NITRO2GRANIT™), Tart Cherry Extract, Beet Root Extract, Green Tea Extract (AssuriTEA™, Kemin, Dubuque IA), and Black Tea Extract (InnovaTEA® , Kemin, Dubuque IA). Participants also were given a whey protein and carbohydrate supplement (Pursuit Rx Recovery Blend, Dymatize Nutrition, Dallas TX) to mix with water and consume immediately after each CrossFit workout. Females were given two scoops (1 serving; 20 g protein; 40 g carbohydrate) of the supplement to combine with 8–10 oz of water and males were given four scoops (2 servings; 40 g protein; 80 g carbohydrate) to combine with 16–20 oz of water. The control group was instructed to refrain from taking any performance oriented dietary supplements over the course of the study and required to consume only water one hour before and one hour after each CrossFit workout.
After every CrossFit workout, participants completed a perception of mood survey, a rate of perceived exertion (RPE) questionnaire, and delayed-onset muscle soreness (DOMS) survey. At the end of each week, the SUP group completed a supplement follow-up questionnaire to ensure compliance and monitor for any side-effects from the supplements.
At baseline testing, participants reported the average number of CrossFit workouts they routinely participated in (3–5 workouts per week) and were told to maintain this level of activity throughout the study. The WODs performed at the CrossFit gym were not the same as WOD1 or WOD2 performed at T1 and T2.
Data analysis
All performance variables were analyzed by a group (SUP vs CTL) × time (T1 vs T2) repeated measures ANOVA. The alpha level was set at 0.05. Confidence Intervals (95%) and magnitude inferences were used to analyze performance variables and body composition measurements. These progressive statistics were used to further investigate meaningfulness and practical importance, as outlined by Hopkins, Marshall, Batterham, and Hanin (Hopkins et al.2009). For determining the degree of beneficial effects, the following ranges were used: <0.5%—most unlikely, almost certainly not; 0.5-5%—very unlikely; 5-25%—unlikely, probably not; 25-75%—possibly; 75-95%—likely, probably; 95–99.5%—very likely; >99.5%—most likely, almost certainly (Hopkins et al.2009).