The Relationship of Physiological and Fitness Variables to Performance in CrossFit®-based Exercise: Preliminary Findings

CrossFit® is a rapidly expanding exercise program as well as an emerging competitive sport. Little is known regarding the correlation of physical fitness measures and performance in CrossFit®-based events. PURPOSE: The purpose of this study was to determine the relationship between various physiological and fitness variables and performance in a typical CrossFit®-based workout. METHODS: Nine male participants (age = 32.2 ± 3.6 yrs; height = 173.1 ± 9.8 cm; weight = 86.1 ± 11.6 kg; BMI = 28.6 ± 1.2 kg/m2) who had performed CrossFit® as their primary exercise program at least 3 days/week for the past 12 months were recruited. Participants performed a test of maximal aerobic fitness (VO2max), a Wingate test, a DEXA scan, a 1RM Clean and Jerk, and a series of exercises that would typically be included in a CrossFit®-based workout. More specifically, participants performed 15 Wall Ball exercises (20 lbs.), 15 Box Jumps (24 in.), 10 Burpees over a barbell, and 10 Kipping Pullups. If all exercises were completed, the participants repeated the exercises in the same order. The participants were asked to stop after 12 min, and the total number of repetitions completed was recorded. Questions regarding the participants’ exercise history and dietary habits were asked. Spearman’s correlation was used to identify relationships between the variables and performance (number of repetitions completed) during the CrossFit®-based workout. Participants were also grouped into “high” (≥ median) or “low” (\u3c median) groups, and independent samples t-tests were used to compare how each group performed during the CrossFit®-based workout. Statistical significance was set at .05. RESULTS: Performance during the CrossFit®-based workout had strong, positive relationships with strength-to-body weight ratio (r = .686; p = .041), 1RM Clean and Jerk (r = .915; p = .001), and years of experience (r = .869; p = .002). Participants with higher strength-to-body weight ratios (p = .036), lower fatigue index (p = .022), lower body fat percentage (p = .022), higher weight lifted during the 1RM Clean and Jerk (p = .017), and more years of experience (p = .027) completed more repetitions during the CrossFit®-based workout. Significance was not found with any other variable. CONCLUSION: Based on these early findings, anaerobic fatigue resistance, body fat percentage, muscular power, and exercise history appear to be significant predictors of performance in CrossFit®-based workouts

Changes in Health and Physical Fitness Parameters After 6 Months of High-intensity Group Exercise in Firefighters: Preliminary Data

The physical demands of firefighting require the men and women employed in this profession to be in optimal physical condition to perform their jobs proficiently, as well as to mitigate the risk of injury. Every year, the city of Addison, TX, budgets many thousands of dollars to the compensation plan for first responders. Most of the funding is used for rehabilitation services due to work related injuries. PURPOSE: While many of these injuries are unavoidable due to the inherent risks of the profession, ensuring proper physical fitness is one of the most effective methods to reduce many of these impairments. The purpose of this preliminary study was to characterize health and fitness parameters in 18 professional firefighters from the city of Addison, TX, prior to a 6-month training program. METHODS: Upon arrival, all participants underwent testing in the following order: body composition, range of motion, anaerobic power, muscular endurance, and cardiorespiratory fitness. All participants also completed a detailed health history questionnaire and answered questions specifically addressing chronic low back pain. RESULTS: The following values were attained from testing: total body fat: 30.1±9.7%; flexibility: 24.9±6.3 cm; peak power: 1068.7±272.9 W; mean power: 636.9±143.4 W; time to peak power 0.57±0.35 sec; pushup: 28.8±14.9; curl up: 22.1±15.8; VO2max: 34.1±5.1 ml/kg/min. CONCLUSION: Based off the comparison of reported means and ACSM’s fitness norms, it can be concluded that improvements are necessary in body composition, muscular endurance, range of motion and cardiorespiratory fitness. With improvements in these physiological variables, tactical performance may be optimally performed in a safer manner

Myogenic Regulatory Factor Expression is Downregulated Following Formoterol Stimulation in Thyroid Hormone Depleted Skeletal Muscle

In skeletal muscle (SKM), gene expression of transcription factors regulating myogenesis are dependent on Thyroid Hormone (TH) signal transduction. Expression of myogenic regulatory factors may be altered due to dysregulated TH metabolism, which may result in SKM dysfunction and intolerance to exercise in individuals with hypothyroidism. PURPOSE: Implement an in vitro model of hypothyroidism in SKM and determine the response of myogenic regulatory factor expression during several stages of myogenesis following TH depletion. Formoterol, an exercise mimetic, was also used to examine the effects of exercise signaling on myogenesis in TH depleted cells. METHODS: Human SKM myoblasts (n = 6 per group) were cultured and differentiated until mature myotube formation (Day 6). Groups included control cells (CON), TH depleted cells (ThD), and TH depleted cells plus formoterol stimulation (ThD+F; 30nm for 3h). Total RNA was extracted during mid-myogenesis (Day 4) and at terminal differentiation (Day 6). Gene expression for myogenic regulatory factors (Myf5, MyoD, MyoG) was determined by qPCR. RESULTS: ThD decreased Myf5 at both Day 4 and Day 6 compared to control (P\u3c0.001). Myf5 was increased following ThD + F compared to ThD at Day 4 (P\u3c0.05). MyoD decreased following ThD at both Day 4 and Day 6 (P\u3c0.001). Further, MyoD was decreased following ThD + F at both Day 4 and Day 6 compared to ThD (P\u3c0.001). ThD had no effect on MyoG at Day 4 and Day 6; however, MyoG was decreased following ThD + F compared to ThD and control at both time points (P\u3c0.001). Data are expressed as mean ± SEM. CONCLUSION: TH depletion had no effect on MyoG but did reduce the expression of both Myf5 and MyoD at both Day 4 and Day 6. Additionally, ThD+F resulted in the lowest expression of MyoG and MyoD for both time points. These results indicate TH depletion and formoterol stimulation may inhibit myotube maturation

Mitochondrial Biogenesis is Dysregulated in Thyroid Hormone Depleted Muscle Cells Despite Stimulatory Effects of Formoterol

Skeletal muscle (SKM) is an important regulator of metabolism and adaptations from exercise training influences mitochondrial function. Thyroid hormone (TH) is a regulator of SKM processes, including mitochondrial biogenesis. PURPOSE: To use an in vitro model of hypothyroidism to test the hypothesis that SKM cells will have dysregulated mitochondrial homeostasis. Additionally, the exercise mimetic, formoterol, was used to determine the effects of exercise signaling on mitochondrial biogenesis. METHODS: Human SKM myoblasts (n = 6 per group) were cultured and differentiated until mature myotube formation (Day 6). Groups included control cells (CON), TH depleted cells (ThD), and TH depleted cells plus formoterol stimulation (ThD+F; 30nM for 3h). Total RNA was extracted during mid-myogenesis (Day 4) and at terminal differentiation (Day 6). Gene expression for Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1 Alpha (PGC-1α), Mitochondrial Transcription Factor A (TFAM), and Nuclear Respiratory Factor 1 (NRF1) was determined by qPCR. Data was analyzed by repeated measures ANOVA. RESULTS: PGC-1α: D4 ThD was decreased compared to D4 ThD+F (-4.6); D4 ThD+F was increased compared to D4 CON (4.6); D6 CON was decreased compared to D6 ThD+F (-2.9); D6 ThD was decreased compared to D6 ThD+F (-3.7). TFAM: D4 ThD+F was greater than D4 CON (3.6); D4 ThD+F was greater than D6 ThD+F (3.6); D6 ThD was decreased compared to D6 CON (-0.55); D6 ThD+F was decreased compared to D6 CON (-0.63). NRF1: D4 ThD was decreased compared to D4 CON (-0.31); D4 ThD was greater than D4 ThD+F (0.36); D4 ThD was greater than D6 ThD (0.17); ThD+F was decreased compared to D4 CON (-0.67); D6 CON was decreased compared to D4 CON (-0.18); D6 ThD was decreased compared to D6 CON (-0.3); D6 ThD+F was decreased compared to D6 CON (-0.42). All reported differences are significant (p \u3c 0.05). Data are expressed as fold changes. CONCLUSION: ThD media resulted in reduced NRF1 signaling in both D4 and D6 with a subsequent decrease in D6 only for TFAM. Formoterol resulted in the expected stimulation of PGC-1α at both D4 and D6, but subsequent signaling for genes associated with mitochondrial biogenesis common to PGC-1α stimulation were lost as a result of TH depletion at D6 only for TFAM and both D4 and D6 for NRF1

Formoterol Stimulation In Vitro Influences Myogenic Regulatory Factors During Myogenesis in Human Skeletal Muscle Cells

The process of myogenesis within skeletal muscle (SKM) is essential for growth and repair and is coordinated via the expression of myogenic regulatory genes. Previous animal studies have reported that formoterol, a beta-adrenergic receptor agonist, has stimulating effects on genes related to SKM mitochondrial function and biogenesis, similar to effects found for exercise. Lesser known is the potential “exercise mimetic” influence that formoterol stimulation may have during the stages of myogenesis, especially in human SKM cells. PURPOSE: To investigate the effects of formoterol stimulation on expression of myogenic regulatory genes during myogenesis in human SKM cells. METHODS: Human SKM myoblasts (n = 6 per group) were cultured and differentiated until mature myotube formation (Day 6). Groups included control cells (CON) and cells stimulated by 30nM formoterol for 3h prior to RNA extraction points (FORM). Total RNA was extracted during mid-myogenesis (Day 4) and at terminal differentiation (Day 6) (a cell culture model of investigating myogenesis). Gene expression for Myogenic factor 5 (Myf5), Myogenic differentiation 1(MyoD), and Myogenin (MyoG) was determined by qPCR. Data was analyzed using repeated measures ANOVA. RESULTS: Myf5: There was no change for either condition for D4. D6 CON was lower than D4 CON (-0.25). D6 FORM was greater than D4 FORM (0.65) and D6 CON (0.75). MyoD: D4 FORM was lower than D4 CON (-0.57). D6 FORM was greater than D4 FORM (0.85) and lower than D6 CON (-0.16). D6 CON was lower than D4 CON (-0.33). MyoG: D4 FORM was lower than D4 CON (-0.72). D6 CON was lower than D4 CON (-0.44). D6 FORM was lower than D6 CON (-0.24). All reported differences are significant (p \u3c 0.05). Data are expressed as fold changes. CONCLUSION: As expected, for the CON group, Myf5, MyoD, and MyoG expression all decreased from D4 mid-myogenesis to D6 terminal myogenesis, indicating finalization of the myogenic gene program. For the FORM group, Myf5 expression was elevated at D6 compared to CON while MyoG and MyoD expression was lower than CON for D4 and D6. The interpretation is that FORM stimulation increased stimulus of D4 myoblast proliferation and, thus, delayed initiation of differentiation. These results, coupled with other preliminary data from our lab showing increased mitochondrial biogenesis with this model of investigation, suggests that this exercise mimetic stimulation may cause shift in the cell towards bioenergetic preference rather than fusion of myotubes

Wide-field dynamic astronomy in the near-infrared with Palomar Gattini-IR and DREAMS

There have been a dramatic increase in the number of optical and radio transient surveys due to astronomical transients such as gravitational waves and gamma ray bursts, however, there have been a limited number of wide-field infrared surveys due to narrow field-of-view and high cost of infrared cameras, we present two new wide-field near-infrared fully automated surveyors; Palomar Gattini-IR and the Dynamic REd All-sky Monitoring Survey (DREAMS). Palomar Gattini-IR, a 25 square degree J-band imager that begun science operations at Palomar Observatory, USA in October 2018; we report on survey strategy as well as telescope and observatory operations and will also providing initial science results. DREAMS is a 3.75 square degree wide-field imager that is planned for Siding Spring Observatory, Australia; we report on the current optical and mechanical design and plans to achieve on-sky results in 2020. DREAMS is on-track to be one of the first astronomical telescopes to use an Indium Galium Arsenide (InGaAs) detector and we report initial on-sky testing results for the selected detector package. DREAMS is also well placed to take advantage and provide near-infrared follow-up of the LSST