Predictors of CrossFit Open Performance.

The 2018 CrossFit Open (CFO) was the initial stage of an annual competition that consisted of five weekly workouts. Current evidence suggests that a variety of fitness parameters are important for progressing beyond this stage, but little is known about which are the most important. To examine relationships between CFO performance, experience, and physiological fitness, sixteen experienced (>2 years) athletes (30.7 ± 6.9 years, 171 ± 12 cm, 78.0 ± 16.2 kg) volunteered to provide information about their training and competitive history, and then complete a battery of physiological assessments prior to competing in the 2018 CFO. Athletes' resting energy expenditure, hormone concentrations, body composition, muscle morphology, cardiorespiratory fitness, and isometric strength were assessed on two separate occasions. Spearman correlations demonstrated significant (p < 0.05) relationships between most variables and performance on each workout. Stepwise regression revealed competition experience (R2 = 0.31-0.63), body composition (R2 = 0.55-0.80), vastus lateralis cross-sectional area (R2 = 0.29-0.89), respiratory compensation threshold (R2 = 0.54-0.75), and rate of force development (R2 = 0.30-0.76) to be the most common predictors. Of these, body composition was the most important. These fitness parameters are known targets with established training recommendations. Though preliminary, athletes may use these data to effectively train for CFO competition.

Physiological differences between advanced CrossFit athletes, recreational CrossFit participants, and physically-active adults.

This investigation examined anthropometric, hormonal, and physiological differences between advanced (ADV; n = 8, 27.8 ± 4.2 years, 170 ± 11 cm, 79.8 ± 13.3 kg) and recreational (REC; n = 8, 33.5 ± 8.1 years, 172 ± 14 cm, 76.3 ± 19.5 kg) CrossFit (CF) trained participants in comparison to physically-active controls (CON; n = 7, 27.5 ± 6.7 years, 171 ± 14 cm, 74.5 ± 14.3 kg). ADV and REC were distinguished by their past competitive success. REC and CON were resistance-trained (>2 years) and exercised on 3-5 days·wk-1 for the past year, but CON utilized traditional resistance and cardiovascular exercise. All participants provided a fasted, resting blood sample and completed assessments of resting metabolic rate, body composition, muscle morphology, isometric mid-thigh pull strength, peak aerobic capacity, and a 3-minute maximal cycle ergometer sprint across two separate occasions (separated by 3-7 days). Blood samples were analyzed for testosterone, cortisol, and insulin-like growth factor-1. Compared to both REC and CON, one-way analysis of variance revealed ADV to possess lower body fat percentage (6.7-8.3%, p = 0.007), greater bone and non-bone lean mass (12.5-26.8%, p ≤ 0.028), muscle morphology characteristics (14.2-59.9%, p < 0.05), isometric strength characteristics (15.4-41.8%, p < 0.05), peak aerobic capacity (18.8-19.1%, p = 0.002), and 3-minute cycling performance (15.4-51.1%, p ≤ 0.023). No differences were seen between REC and CON, or between all groups for resting metabolic rate or hormone concentrations. These data suggest ADV possess several physiological advantages over REC and CON, whereas similar physiological characteristics were present in individuals who have been regularly participating in either CF or resistance and cardiovascular training for the past year.

Safety of Short-Term Supplementation with Methylliberine (Dynamine®) Alone and in Combination with TeaCrine® in Young Adults.

Methylliberine (Dynamine®; DYM) and theacrine (Teacrine®; TCR) are purine alkaloids purported to have similar neuro-energetic effects as caffeine. There are no published human safety data on DYM, and research on TCR is limited. The purpose of this study was to examine the effect of four weeks of DYM supplementation with and without TCR on cardiovascular function and blood biomarkers. One-hundred twenty-five men and women (mean age 23.0 yrs, height 169.7 cm, body mass 72.1 kg; n = 25/group) were randomly assigned to one of five groups: low-dose DYM (100 mg), high-dose DYM (150 mg), low-dose DYM with TCR (100 mg + 50 mg), high-dose DYM with TCR (150 mg + 25 mg) , and placebo. Regardless of group and sex, significant main effects for time were noted for heart rate, systolic blood pressure, and QTc (p < 0.001), high-density lipoproteins (p = 0.002), mean corpuscular hemoglobin (p = 0.018), basophils (p = 0.006), absolute eosinophils (p = 0.010), creatinine (p = 0.004), estimated glomerular filtration rate (p = 0.037), chloride (p = 0.030), carbon dioxide (p = 0.023), bilirubin (p = 0.027), and alanine aminotransferase (p = 0.043), among others. While small changes were found in some cardiovascular and blood biomarkers, no clinically significant changes occurred. This suggests that DYM alone or in combination with TCR consumed at the dosages used in this study does not appear to negatively affect markers of health over four weeks of continuous use.

Predicting success in an undergraduate exercise science program using science-based admission courses.

Student success is an important focus within higher education as it relates to retention, progression, and graduation rates. Limited research exists examining the predictors of success within an undergraduate Exercise Science program. The purpose of this investigation was to examine the viability of an admission policy implemented within an undergraduate Exercise Science program as a method of predicting student success. Data from 652 students from 2012 through 2018 were collected from the University's Enterprise Information Management system. Regression analysis indicated ES 2100, an introductory Exercise Science course, was the best predictor of student performance in required major courses. Furthermore, the results indicated performance in general education courses, including English Composition II, Precalculus, General Chemistry II Laboratory, Human Anatomy and Physiology II, and General Psychology were also significantly related to performance in the required major courses, after controlling for performance in other courses. The results of the investigation provide insight regarding future success within required major courses in the program. This knowledge can be valuable when examining methods to improve retention of students, progression, minimizing repeat attempts at courses, and improving graduation rates. In conclusion, the identification of these courses, related to student success, may provide valuable insight for other Exercise Science-related programs that are considering implementing a program admission policy.

A Comparison of Body Composition Across Two Phases of the Menstrual Cycle Utilizing Dual-Energy X-Ray Absorptiometry, Air Displacement Plethysmography, and Bioelectrical Impedance Analysis.

The purpose of this investigation was to utilize several different technologies to compare body composition results across two phases of the menstrual cycle, and to investigate whether being on hormonal birth control or not has any effect on results. The secondary purpose was to determine if body satisfaction or perception of fluid retention differed across phases or between groups. A total of 39 females with a mean age of 26 ± 7 yrs were included in the study, 15 were on hormonal birth control (BC) and 24 were not (non-BC). Participants came into the lab for two trials: once while menstruating and another during the estimated pre-ovulation phase of the menstrual cycle. Demographic and body satisfaction questionnaires were completed prior to body composition testing. This testing included dual-energy x-ray absorptiometry, BOD POD®, and three separate bioelectrical impedance analyses. Participants completed the body satisfaction questionnaire and all body composition tests on each trial. No significant differences (P > 0.05) were found between body fat percentage or total body water estimates taken during menses and pre-ovulation for the BC or non-BC group. There was no significant difference (P > 0.05) in overall body satisfaction across the two phases for the non-BC group, though the BC group had significantly lower body satisfaction during menses (P < 0.01). Participants in both groups identified feeling more bloated during menses (P < 0.001). Results suggest that menses should not affect the reliability of body composition estimates regardless of whether or not females are on hormonal BC.

Fifty-three hours of total sleep deprivation has no effect on rewarming from cold air exposure.

OBJECTIVE: Sleep deprivation and cold air exposure are both experienced in occupational and military settings but the combined effects of these 2 stressors is unknown. The purpose of this study was to determine the effects of 53 hours of total sleep deprivation on thermoregulation during the rewarming phase (25°C air) after acute cold air exposure (10°C air). METHODS: Eight young men underwent 2 trials in which they either received 7 hours of sleep at night or were totally sleep deprived. On 3 consecutive mornings, the subjects underwent 2 hours of cold air exposure followed by 2 hours of rewarming. Rectal temperature, mean skin temperature, oxygen consumption, and thermal sensation were measured. RESULTS: Rewarming from acute cold air exposure caused a decline in rectal temperature (~0.5°C) each day but this was not different between subjects who were totally sleep deprived and subjects who received 7 hours of sleep at night. During this same period, mean skin temperature increased (from ~22°C to 27°C), oxygen consumption decreased (from ~7 to 4 mL·kg(-1)·min(-1)), and the participants felt warmer. CONCLUSIONS: Under the conditions of the present study, sleep-deprived persons are not at a greater risk for a decline in rectal temperature (ie, a hypothermic afterdrop) during rewarming from cold air.