Exertional rhabdomyolysis in a 21-year-old, healthy female after performing three sets of the biceps curl exercise to failure with 30% 1RM: A case report

Background: The optimal resistance training program to elicit muscle hypertrophy has been consistently debated and researched. Although 3 sets of 10 repetitions at 70-80% of the 1-repetition maximum (1RM) is widely recommended, recent studies have shown that low-load (~30% 1RM), high-repetition (3 sets of 30-40 repetitions) resistance training can elicit similar muscular hypertrophy. Therefore, this type of resistance training has gained popularity, perhaps because less weight is lifted for a longer duration. In the process of testing this hypothesis in a research study in our laboratory, a subject diagnosed with exertional rhabdomyolysis after completing a single resistance training session that involved 3 sets to failure at 30% 1RM. Exertional rhabdomyolysis is a condition characterized by the excessive breakdown of striated skeletal muscle that releases proteins from the muscle cell, particularly myoglobin, into the blood that can be toxic to the kidneys and is a significant health concern. Case Report: Reviewed were the events leading up to and throughout the diagnosis of exertional rhabdomyolysis in a healthy, recreationally-trained, 21-year-old female that was enrolled in a study that compared the acute effects of the traditional high-load, low-repetition versus low-load, high-repetition resistance training. The subject completed a total of 143 repetitions of the bilateral dumbbell bicep curl exercise. Three days post-exercise she reported excessive muscle soreness and swelling and sought medical attention. She was briefly hospitalized and then discharged with instructions to take acetaminophen for soreness, drink plenty of water, rest, and monitor her creatine kinase (CK) concentrations. Changes in the subject’s CK concentrations, ultrasound-determined muscle thickness and echo intensity were monitored over a 14-day period are reported. Discussion: This case illustrates the potential risk of developing exertional rhabdomyolysis after a low-load, high-repetition resistance training session in healthy, young, recreationally-trained women. The fact that exertional rhabdomyolysis is a possible outcome is enough to warrant caution when prescribing this type of resistance exercise

Endogenous versus exogenous carbohydrate oxidation measured by stable isotopes in pre-pubescent children plus 13C abundances in foods consumed three days prior

Purpose: The purposes of the present study were to (a) examine resting metabolism, substrate utilization, and endogenous versus exogenous carbohydrate (CHO) oxidation before and after 30-g rapidly-digesting carbohydrate (RDC) ingestion using indirect calorimetry and breath test analysis of stable isotope concentrations in pre-pubescent children and (b) report the 13C abundances in foods consumed for three days prior. Methods: Nineteen children (n 1⁄4 10 boys, n 1⁄4 9 girls) at Tanner stage I or II participated (mean age ± 95% CI 1⁄4 9.84 ± 0.77 y) in this study. Food was administered to the children for three days preceding their scheduled breath tests. Breath tests and indirect calorimetry were performed after an 8-h fast before and 60 min following consumption of a 30-g simple RDC drink consisting of maltodextrin and sucrose. Open circuit spirometry and indirect calorimetry monitored resting metabolism and CHO oxidation. Separate breath samples were taken every 15 min. Samples of all foods and breath samples were analyzed for 13C and 12C abundances with a stable-isotope mass spectrometer. Results: 13C in expired breath samples were 23.81 + 1.64‰ at baseline and increased every 15 min after consumption of the CHO drink (p \u3c 0.001e0.009). Cumulative total, endogenous, and exogenous CHO utilization increased during the post-prandial period (p \u3c 0.001). Endogenous CHO oxidation was consistently greater than exogenous CHO oxidation (p \u3c 0.001e0.002). Blood glucose was elevated from baseline at 30- and 60-min post-prandial (p \u3c 0.001). Insulin did not change over time (p 1⁄4 0.184). Conclusions: The foods provided during the 3-day controlled diet effectively minimized 13C variation prior to metabolic testing. The 13C abundances of foods reported herein should serve as practical recommendations to reduce 13C intake before breath tests. While endogenous CHO oxidation remained greater in proportion to exogenous CHO oxidation, these findings suggest that even a relatively small amount of RDC can increase exogenous CHO oxidation and blood glucose in normal-weight children. To further examine shifts in endogenous versus exogenous CHO utilization, we recommend that future studies take steps to minimize 13C variation before breath tests and examine changes in substrate metabolism at rest and during exercise in normal weight and overweight pre-pubescent children. Clinical trial registration number: NCT03185884

HETDEX Public Source Catalog 1: 220K Sources Including Over 50K Lyman Alpha Emitters from an Untargeted Wide-area Spectroscopic Survey

We present the first publicly released catalog of sources obtained from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). HETDEX is an integral field spectroscopic survey designed to measure the Hubble expansion parameter and angular diameter distance at 1.88<z<3.52 by using the spatial distribution of more than a million Ly-alpha-emitting galaxies over a total target area of 540 deg^2. The catalog comes from contiguous fiber spectra coverage of 25 deg^2 of sky from January 2017 through June 2020, where object detection is performed through two complementary detection methods: one designed to search for line emission and the other a search for continuum emission. The HETDEX public release catalog is dominated by emission-line galaxies and includes 51,863 Ly{\alpha}-emitting galaxy (LAE) identifications and 123,891 OII-emitting galaxies at z<0.5. Also included in the catalog are 37,916 stars, 5274 low-redshift (z<0.5) galaxies without emission lines, and 4976 active galactic nuclei. The catalog provides sky coordinates, redshifts, line identifications, classification information, line fluxes, OII and Ly-alpha line luminosities where applicable, and spectra for all identified sources processed by the HETDEX detection pipeline. Extensive testing demonstrates that HETDEX redshifts agree to within deltaz < 0.02, 96.1% of the time to those in external spectroscopic catalogs. We measure the photometric counterpart fraction in deep ancillary Hyper Suprime-Cam imaging and find that only 55.5% of the LAE sample has an r-band continuum counterpart down to a limiting magnitude of r~26.2 mag (AB) indicating that an LAE search of similar sensitivity with photometric pre-selection would miss nearly half of the HETDEX LAE catalog sample. Data access and details about the catalog can be found online at http://hetdex.org/.Comment: 38 pages, 20 figures. Data access and details about the catalog can be found online at http://hetdex.org/. A copy of the catalogs presented in this work (Version 3.2) is available to download at Zenodo doi:10.5281/zenodo.744850

Oxygenation and Activation of the Vastus Lateralis during Dynamic Constant External Resistance Leg Extension Muscle Actions in Older Women with and without Sarcopenia

The purpose of the present study was to compare muscle strength, size, activation, and oxygenation between older women with and without sarcopenia during dynamic fatiguing leg extension bouts with high (5-repetition maximum[5-RM]) and low (30% of estimated 1-RM[30%1-RM]) loads. Eleven women (n = 6 non-sarcopenic [mean ± SE; age = 75.8 ± 2.6y] and n = 5 sarcopenic [age = 74.5 ± 3.1y]) were screened for eligibility and sarcopenic status. Descriptive assessments including demographics (age, height, and weight), body composition by dual-energy x-ray absorptiometry (fat mass[FM], fat-free mass[FFM] and percent body fat[BF%]), muscle size by ultrasonography (leg extensor muscle cross-sectional area[mCSA], vastus lateralis [VL] thickness, subcutaneous fat thickness, and echo intensity[EI]), muscle strength (leg extensor[5-RM], handgrip[HG]), muscular endurance (30%1-RM to exhaustion), and functionality (gait speed) were measured. During the 5-RM and 30%1-RM tasks, muscle activation was measured by surface electromyography (EMG), while muscle oxygenation was measured by near-infrared spectroscopy (NIRS). FM, BF%, subcutaneous fat, and EI indicated the presence of sarcopenic obesity (p ≤ 0.05). Relative skeletal mass index and HG were lower (p ≤ 0.05) in the sarcopenic group, but no other descriptive measures were different between groups (p \u3e 0.05). Despite no differences (p \u3e 0.05) in leg extensor muscle size or strength between sarcopenic and non-sarcopenic older women, the sarcopenic women exhibited 13 – 21% lower (p ≤ 0.05) muscle oxygenation across all repetitions of the high- and low-load tasks. EMG amplitude (EMGRMS)increased, while EMG mean power frequency (EMGMPF) decreased (p ≤ 0.05) across repetitions during both tasks, but there were no differences between groups. These findings suggest the presence of a clinical sarcopenic classification may not uniformly impact the size or strength of all muscles. If greater variability is expected among muscle activation strategies of older adults, using EMG to distinguish between sarcopenic and non-sarcopenic women without differences in leg extensor muscle size, strength, or endurance may be difficult. However, lower muscle oxygenation, which may reflect skeletal muscle blood flow, in clinically sarcopenic older women may be important to consider when recommending exercise or nutrition interventions for either oxygen or dietary nutrient delivery. Advisor: Joel Crame

State Population Influences Athletic Performance Combine Test Scores in High School-Aged American Football Players

This study compared athletic performance differences among high school American football combine participants originating from states of different population sizes. High school-aged American football players (n=7,214) who had participated in athletic performance combines between March 2015 and January 2016 were included in this analysis. Data included combine date and location, school state of origin, football position, class, height, weight, 10-, 20-, and 40-yd dash times, pro-agility, L-cone drill, vertical jump, broad jump, and power push-up. Participants were separated into high- (state population\u3e10,000,000; HIGH; n=2,804), mid- (state population=5,000,000-9,999,999; MID; n=2,911), or low-population (state population\u3c5,000,000; LOW; n=1,499) state of origin. Data were allometrically scaled to account for differences in body mass across high school grade levels and American football positions. All statistical analyses were performed on the allometrically scaled data. LOW athletes performed better than HIGH athletes in the 20-yd dash (p≤0.01). LOW athletes performed better than HIGH and MID in the 40-yd dash, proagility, broad jump, and power push-up (p\u3c0.01). LOW and HIGH athletes performed better than MID in the Lcone and vertical jump (p\u3c0.01). When considering population size, athletes originating from LOW states may demonstrate higher levels of athletic performance in football combine events hypothetically due to more opportunities for sports participation and playing time, leading to greater athletic development. Youth and high school coaches in MID and HIGH states might consider providing more opportunities for playing and individualized coaching to encourage long-term athletic development

State Population Influences Athletic Performance Combine Test Scores in High School-Aged American Football Players

International Journal of Exercise Science 12(6): 256-262, 2019. This study compared athletic performance differences among high school American football combine participants originating from states of different population sizes. High school-aged American football players (n=7,214) who had participated in athletic performance combines between March 2015 and January 2016 were included in this analysis. Data included combine date and location, school state of origin, football position, class, height, weight, 10-, 20-, and 40-yd dash times, pro-agility, L-cone drill, vertical jump, broad jump, and power push-up. Participants were separated into high- (state population\u3e10,000,000; HIGH; n=2,804), mid- (state population=5,000,000-9,999,999; MID; n=2,911), or low-population (state population\u3c5,000,000; LOW; n=1,499) state of origin. Data were allometrically scaled to account for differences in body mass across high school grade levels and American football positions. All statistical analyses were performed on the allometrically scaled data. LOW athletes performed better than HIGH athletes in the 20-yd dash (p≤0.01). LOW athletes performed better than HIGH and MID in the 40-yd dash, pro-agility, broad jump, and power push-up (p\u3c0.01). LOW and HIGH athletes performed better than MID in the L-cone and vertical jump (p\u3c0.01). When considering population size, athletes originating from LOW states may demonstrate higher levels of athletic performance in football combine events hypothetically due to more opportunities for sports participation and playing time, leading to greater athletic development. Youth and high school coaches in MID and HIGH states might consider providing more opportunities for playing and individualized coaching to encourage long-term athletic development

Exertional rhabdomyolysis in a 21-year-old, healthy female after performing three sets of the biceps curl exercise to failure with 30% 1RM: A case report

Background: The optimal resistance training program to elicit muscle hypertrophy has been consistently debated and researched. Although 3 sets of 10 repetitions at 70-80% of the 1-repetition maximum (1RM) is widely recommended, recent studies have shown that low-load (~30% 1RM), high-repetition (3 sets of 30-40 repetitions) resistance training can elicit similar muscular hypertrophy. Therefore, this type of resistance training has gained popularity, perhaps because less weight is lifted for a longer duration. In the process of testing this hypothesis in a research study in our laboratory, a subject diagnosed with exertional rhabdomyolysis after completing a single resistance training session that involved 3 sets to failure at 30% 1RM. Exertional rhabdomyolysis is a condition characterized by the excessive breakdown of striated skeletal muscle that releases proteins from the muscle cell, particularly myoglobin, into the blood that can be toxic to the kidneys and is a significant health concern. Case Report: Reviewed were the events leading up to and throughout the diagnosis of exertional rhabdomyolysis in a healthy, recreationally-trained, 21-year-old female that was enrolled in a study that compared the acute effects of the traditional high-load, low-repetition versus low-load, high-repetition resistance training. The subject completed a total of 143 repetitions of the bilateral dumbbell bicep curl exercise. Three days post-exercise she reported excessive muscle soreness and swelling and sought medical attention. She was briefly hospitalized and then discharged with instructions to take acetaminophen for soreness, drink plenty of water, rest, and monitor her creatine kinase (CK) concentrations. Changes in the subject’s CK concentrations, ultrasound-determined muscle thickness and echo intensity were monitored over a 14-day period are reported. Discussion: This case illustrates the potential risk of developing exertional rhabdomyolysis after a low-load, high-repetition resistance training session in healthy, young, recreationally-trained women. The fact that exertional rhabdomyolysis is a possible outcome is enough to warrant caution when prescribing this type of resistance exercise

Endogenous versus exogenous carbohydrate oxidation measured by stable isotopes in pre-pubescent children plus 13C abundances in foods consumed three days prior

Purpose: The purposes of the present study were to (a) examine resting metabolism, substrate utilization, and endogenous versus exogenous carbohydrate (CHO) oxidation before and after 30-g rapidly-digesting carbohydrate (RDC) ingestion using indirect calorimetry and breath test analysis of stable isotope concentrations in pre-pubescent children and (b) report the 13C abundances in foods consumed for three days prior. Methods: Nineteen children (n 1⁄4 10 boys, n 1⁄4 9 girls) at Tanner stage I or II participated (mean age ± 95% CI 1⁄4 9.84 ± 0.77 y) in this study. Food was administered to the children for three days preceding their scheduled breath tests. Breath tests and indirect calorimetry were performed after an 8-h fast before and 60 min following consumption of a 30-g simple RDC drink consisting of maltodextrin and sucrose. Open circuit spirometry and indirect calorimetry monitored resting metabolism and CHO oxidation. Separate breath samples were taken every 15 min. Samples of all foods and breath samples were analyzed for 13C and 12C abundances with a stable-isotope mass spectrometer. Results: 13C in expired breath samples were 23.81 + 1.64‰ at baseline and increased every 15 min after consumption of the CHO drink (p \u3c 0.001e0.009). Cumulative total, endogenous, and exogenous CHO utilization increased during the post-prandial period (p \u3c 0.001). Endogenous CHO oxidation was consistently greater than exogenous CHO oxidation (p \u3c 0.001e0.002). Blood glucose was elevated from baseline at 30- and 60-min post-prandial (p \u3c 0.001). Insulin did not change over time (p 1⁄4 0.184). Conclusions: The foods provided during the 3-day controlled diet effectively minimized 13C variation prior to metabolic testing. The 13C abundances of foods reported herein should serve as practical recommendations to reduce 13C intake before breath tests. While endogenous CHO oxidation remained greater in proportion to exogenous CHO oxidation, these findings suggest that even a relatively small amount of RDC can increase exogenous CHO oxidation and blood glucose in normal-weight children. To further examine shifts in endogenous versus exogenous CHO utilization, we recommend that future studies take steps to minimize 13C variation before breath tests and examine changes in substrate metabolism at rest and during exercise in normal weight and overweight pre-pubescent children. Clinical trial registration number: NCT03185884

Stature, Body Mass, and BMI in High School American Football Players: Appropriate determinants of obesity prevalence?

The purpose of this study was to evaluate stature (HT), weight (WT), body mass index (BMI), and obesity prevalence based on BMI categories in a large sample (n = 7,175) of high school American football players enrolled as freshmen, sophomores, or juniors. Players were categorized by their positions: offensive linemen (OL), defensive linemen (DL), tight end (TE), defensive end (DE), linebacker (LB), running back (RB), quarterback (QB), defensive back (DB), and wide receiver (WR). HT, WT, and BMI increased as grade increased among all positions. OL and DL had the greatest HT, WT, and BMI (p≤0.05). Obesity prevalence was greatest in OL and DL. When accounting for age-related increases in BMI, WT increased to a greater degree than HT. If HT is an indirect indicator of skeletal size, while WT is more influenced by soft tissue, then the age-related BMI increases in the present study may be largely accounted for by soft tissue changes rather than skeletal growth. Even though obesity prevalence in OL (94.5%) and DL (78.4%) positions was greater than all other positions as determined from BMI, it is impossible to know the allocations of fat-free and fat mass—particularly in American football athletes. If obesity continues to be defined as an unhealthy accumulation of fat, then athletes who may have a greater relative proportion of lean soft tissue should not be classified as obese using BMI (WT÷HT²). More sophisticated, reliable, and sensitive measure of body composition, such as skinfolds, may be more appropriate field measurements

Test-Retest Reliability of Static and Counter-Movement Power Push-Up Tests in 6-16-Year-Old Male Athletes

The primary purpose of this study was to evaluate test-retest reliability of the static (SP) and counter-movement (CMP) power push-up (PPU) test in young male athletes. The secondary purpose was to compare the reliability of vertical ground reactions forces versus torque measurements during the PPU tests. Twenty males (age = 11.60 ± 1.15 y) performed SPs and CMPs on force plates with the knees as the fulcrum on two laboratory visits separated by 2-7 days. Performance measurements included peak force (PF), rate of force development (RFD), peak torque (PT), rate of torque development (RTD), peak power (PP), average power (AP), eccentric impulse (ECC), and concentric impulse (CON) for both PPU techniques. Age, maturity offset, height, body mass, fat-free mass (FFM), and estimated arm cross sectional area (eCSA) were obtained as measurements of growth. Intraclass correlation coefficients (ICC), standard errors of measurement (SEM), coefficients of variation (CV), and minimum detectable changes (MDC) were reported. Only PF (ICC = 0.87-0.88, SEM = 59-84 N) and PT (ICC = 0.89-0.90, SEM = 60-88 N·m) showed acceptable reliability. Neither RFD, RTD, PP, AP, ECC, or CON were reliable outcomes. There were no meaningful differences between force-time and torque-time curve measurements. The SP showed slightly lower CVs (33-34%) than the CMP (CVs = 39-40%). Coaches and practitioners would need to see 58-71% increases in upper-body strength measurements evaluated via PPU on force plates to be 95% confident that the improvements exceeded the measurement variability