Interaction of Surface Type, Temperature, and Week of Season on Concussion Risk in the National Football League: A Bayesian Analysis.

BACKGROUND: Artificial turf fields and environmental conditions may influence sports concussion risk, but existing research is limited by uncontrolled confounding factors, limited sample size, and the assumption that risk factors are independent of one another. The purpose of this study was to examine how playing surface, time of season, and game temperature relate to diagnosed concussion risk in the National Football League (NFL). METHODS: This retrospective cohort study examined data from the 2012 to the 2019 NFL regular season. We fit Bayesian negative binomial regression models to relate how playing surface, game temperature, and week of the season independently related to diagnosed concussion risk and any interactions among these factors. RESULTS: We identified 1096 diagnosed concussions in 1830 games. There was a >99% probability that concussion risk was reduced on grass surface (median incidence rate ratio [IRR] = 0.78 [95% credible interval: 0.68, 0.89]), >99% probability that concussion risk was lower at higher temperatures (IRR = 0.85 [0.76,0.95] for each 7.9 °C), and >91% probability that concussion risk increased with each week of the season (IRR = 1.02 [1.00,1.04]). There was an >84% probability for a surface × temperature interaction (IRR = 1.01 [0.96, 1.28]) and >75% probability for a surface × week interaction (IRR = 1.02 [0.99, 1.05]). CONCLUSIONS: Diagnosed concussion risk is increased on artificial turf compared with natural grass, and this is exacerbated in cold weather and, independently, later in the season. The complex interplay between these factors necessitates accounting for multiple factors and their interactions when investigating sports injury risk factors and devising mitigation methods.

Modelling the maximal active consumption rate and its plasticity in humans-perspectives from hot dog eating competitions.

Gut capacity and plasticity have been examined across multiple species, but are not typically explored in the context of extreme human performance. Here, I estimate the theoretical maximal active consumption rate (ACR) in humans, using 39 years of historical data from the annual Nathan's Famous Hot Dog Eating Contest. Through nonlinear modelling and generalized extreme value analysis, I show that humans are theoretically capable of achieving an ACR of approximately 832 g min-1 fresh matter over 10 min duration. Modelling individual performances across 5 years reveals that maximal ACR significantly increases over time in 'elite' competitive eaters, likely owing to training effects. Extreme digestive plasticity suggests that eating competition records are quite biologically impressive, especially in the context of carnivorous species and other human athletic competitions.

Optimizing Intersession Reliability of Heart Rate Variability-The Effects of Artifact Correction and Breathing Type.

Gisselman, AS, D'Amico, M, and Smoliga, JM. Optimizing intersession reliability of heart rate variability-the effects of artifact correction and breathing type. J Strength Cond Res 34(11): 3199-3207, 2020-This study aimed to comprehensively investigate the reliability of multiple heart rate variability (HRV) parameters and to explore the influence of artifact removal and breathing condition on HRV reliability. Resting HRV was collected using Polar Team monitors on 41 participants (age: 19.9 ± 1.2 years; 28 females and 13 males) during 2 separate days. Within each session, participants performed 10 minutes each of spontaneous and controlled breathing (randomized order). Kubios HRV analysis software was used to analyze 180-second data epochs using "low" or "strong" artifact removal. Relative reliability was assessed using intraclass correlation coefficient (ICC2,1), and absolute reliability was quantified using mean-normalized SEM%. Time-domain and nonlinear parameters produced poor to good intersession agreement (ICC = 0.34-0.68; SEM% = 11.0-39.0) with "low" artifact removal, regardless of breathing condition. Frequency-domain parameters demonstrated fair intersession agreement during controlled breathing (ICC = 0.40-0.45; SEM% = 26.0-70.0) but poor agreement during spontaneous breathing (ICC = 0.07-0.13; SEM% = 32.0-81.0). Minimal differences in ICCs were observed between "low" and "strong" artifact removal. Thus, this study provides 3 practical applications: (a) HRV monitoring is most reliable when using time-domain and nonlinear parameters, regardless of breathing or filtering condition, but no single parameter is especially reliable. The large variation and poor intersession reliability of frequency indices during spontaneous breathing are improved by controlling breathing rate; (b) "Low" artifact removal seems superior to more aggressive artifact removal; and (c) intersession differences in HRV measurements <30% may be indicative of normal daily variation rather than true physiologic changes.

Team Logo Predicts Concussion Risk: Lessons in Protecting a Vulnerable Sports Community from Misconceived, but Highly Publicized Epidemiologic Research.

BACKGROUND: Observational research has linked altitude to concussion risk, but the physiologic and epidemiologic bases for this association remain questionable. METHODS: We performed a retrospective cohort study by analyzing four seasons of National Football League data from a widely used database (Concussion Watch) to determine if previous claims that altitude ≥196 m reduced concussion risk were replicable and whether an arbitrary predictor variable (animal vs. non-animal team logo) was related to concussion risk. Relative risk (RR) and 95% confidence intervals (95% CIs) were computed. RESULTS: The previous association with altitude was reproduced for earlier seasons, but not replicable for recent seasons (RR = 0.92 [95% CI = 0.70, 1.22]). Across four combined seasons, "higher altitude" (RR = 0.78 [0.64, 0.96]) and animal logo (RR = 0.75 [0.63, 0.89]) were similarly associated with reduced concussion risk. CONCLUSIONS: Inconsistent epidemiologic effects, combined with weak physiologic rationale, suggest links between altitude and concussion are coincidental. Interdisciplinary critique of concussion research is necessary to ensure that marketing claims and clinical recommendations are scientifically justified.See video abstract at, http://links.lww.com/EDE/B234.

A Comparison of Body Segment Inertial Parameter Estimation Methods and Joint Moment and Power Calculations During a Drop Vertical Jump in Collegiate Female Soccer Players.

Athletic individuals may differ in body segment inertial parameter (BSIP) estimates due to differences in body composition, and this may influence calculation of joint kinetics. The purposes of this study were to (1) compare BSIPs predicted by the method introduced by de Leva1 with DXA-derived BSIPs in collegiate female soccer players, and (2) examine the effects of these BSIP estimation methods on joint moment and power calculations during a drop vertical jump (DVJ). Twenty female NCAA Division I soccer players were recruited. BSIPs of the shank and thigh (mass, COM location, and radius of gyration) were determined using de Leva's method and analysis of whole-body DXA scans. These estimates were used to determine peak knee joint moments and power during the DVJ. Compared with DXA, de Leva's method located the COM more distally in the shank (P = .008) and more proximally in the thigh (P < .001), and the radius of gyration of the thigh to be further from the thigh COM (P < .001). All knee joint moment and power measures were similar between methods. These findings suggest that BSIP estimation may vary between methods, but the impact on joint moment calculations during a dynamic task is negligible.

Translating dosages from animal models to human clinical trials--revisiting body surface area scaling.

Body surface area (BSA) scaling has been used for prescribing individualized dosages of various drugs and has also been recommended by the U.S. Food and Drug Administration as one method for using data from animal model species to establish safe starting dosages for first-in-human clinical trials. Although BSA conversion equations have been used in certain clinical applications for decades, recent recommendations to use BSA to derive interspecies equivalents for therapeutic dosages of drug and natural products are inappropriate. A thorough review of the literature reveals that BSA conversions are based on antiquated science and have little justification in current translational medicine compared to more advanced allometric and physiologically based pharmacokinetic modeling. Misunderstood and misinterpreted use of BSA conversions may have disastrous consequences, including underdosing leading to abandonment of potentially efficacious investigational drugs, and unexpected deadly adverse events. We aim to demonstrate that recent recommendations for BSA are not appropriate for animal-to-human dosage conversions and use pharmacokinetic data from resveratrol studies to demonstrate how confusion between the "human equivalent dose" and "pharmacologically active dose" can lead to inappropriate dose recommendations. To optimize drug development, future recommendations for interspecies scaling must be scientifically justified using physiologic, pharmacokinetic, and toxicology data rather than simple BSA conversion.

A stepwise reduction in plasma and salivary nitrite with increasing strengths of mouthwash following a dietary nitrate load.

Nitric Oxide (NO) bioavailability is essential for vascular health. Dietary supplementation with inorganic nitrate, which is abundant in vegetables and roots, has been identified as an effective means of increasing vascular NO bioavailability. Recent studies have shown a reduction in resting blood pressures in both normotensive and hypertensive subjects following ingestion of inorganic nitrate. Oral bacteria play a key role in this process and the use of strong antibacterial mouthwash rinses can disable this mechanism. Hence, mouthwash usage, a $1.4 billion market in the US, may potentially be detrimental to cardiovascular health. The purpose of this study was to examine the effects of different strengths of commercially available mouthwash products on salivary and plasma nitrate and nitrite concentrations following 8.4 mmol inorganic nitrate load (beetroot juice). Specifically, we examined the effects of Listerine antiseptic mouthwash, Cepacol antibacterial mouthwash, and Chlorhexidine mouthwash versus control (water). Twelve apparently healthy normotensive males (36 ± 11 yrs) completed four testing visits in a randomized order, separated by one week. Testing consisted of blood pressure (BP), and saliva and venous blood collection at baseline and each hour for 4 h. Following baseline-testing participants consumed 140 ml of beet juice and then 15 min later gargled with 5 mL of assigned mouthwash. Testing and mouthwash rinse was repeated every hour for 4 h. Linear mixed effects models, followed by pairwise comparisons where appropriate, were used to determine the influence of treatment and time on plasma and saliva nitrate and nitrite, and BP. Plasma and salivary nitrate increased above baseline (time effect) for all conditions (p ≤ 0.01). There were time (p ≤ 0.01), treatment (p ≤ 0.01), and interaction (p ≤ 0.05) effects for plasma and salivary nitrite. There was a treatment effect on systolic BP (p ≤ 0.05). Further examination revealed a differentiation of plasma and salivary nitrite concentration between control/antiseptic and antibacterial/chlorhexidine treatments. When examined in this manner there was a reduction in both SBP (p ≤ 0.01) and mean arterial BP (p ≤ 0.05) from the antibacterial/chlorhexidine treatments. These results suggest a potentially differentiating effect of different commercially available mouthwash solutions on plasma and salivary nitrite concentrations and resting blood pressure responses. This raises potential public health related questions on the appropriate widespread usage of different mouthwash formulations.

Upper-Extremity Physical-Performance Tests in College Athletes.

CONTEXT: Physical-performance tests (PPTs) are commonly used in rehabilitation and injury-prevention settings, yet normative values of upper-extremity PPTs have not been established in high-level athletes. OBJECTIVE: To establish normative data values for the Closed Kinetic Chain Upper-Extremity Stability Test (CKCUEST) and Upper-Quarter Y-Balance Test (UQYBT) in college athletes and compare results between sports and to analyze the relationship between the 2 tests. DESIGN: Observational. SETTING: Laboratory/athletic facility. PARTICIPANTS: 257 (118 male, 139 female) Division I athletes participating in basketball, soccer, baseball, lacrosse, volleyball, track and field, and cross-country. INTERVENTION: CKCUEST and UQYBT scores were recorded as part of a comprehensive injury-risk screening battery. MAIN OUTCOME MEASURE: Pearson correlations assessed the relationship between all measures of the CKCUEST and UQYBT. A factorial ANOVA and a repeated-measures ANOVA (arm dominance) were used to assess interactions between sex, year in school, and sport for CKCUEST and UQYBT scores. RESULTS: Normative values for the CKCUEST and UQYBT were established for 9 men's and women's college sports. No significant relationships were found between PPT scores. Men scored significantly higher than women for the CKCUEST (P = .002) and UQYBT (P = .010). Baseball players scored significantly higher than athletes from all other sports for the UQYBT (P < .001) but showed nonsignificant trends of lower scores for the CKCUEST than lower-extremity-dominant athletes such as runners (P = .063) and lacrosse players (P = .058). CONCLUSIONS: Results suggest that average CKCUEST and UQYBT scores in Division I athletes are distinct from those previously reported in recreationally active populations and that performance differences exist between sexes and sports. In addition, the CKCUEST and UQYBT appear to measure different constructs of performance and may complement each other as part of a screening battery.

Faces and fitness: attractive evolutionary relationship or ugly hypothesis?

In recent years, various studies have attempted to understand human evolution by examining relationships between athletic performance or physical fitness and facial attractiveness. Over a wide range of five homogeneous groups (n = 327), there is an approximate 3% shared variance between facial attractiveness and athletic performance or physical fitness (95% CI = 0.5-8%, p = 0.002). Further, studies relating human performance and attractiveness often have major methodological limitations that limit their generalizability. Thus, despite statistical significance, the association between facial attractiveness and human performance has questionable biological importance. Here, we present a critique of these studies and provide recommendations to improve the quality of future research in this realm.

Risk factors associated with lower extremity stress fractures in runners: a systematic review with meta-analysis.

BACKGROUND: Stress fractures are common overuse injuries with up to 95% occurring in the lower extremities. Among runners, stress fractures account for 15-20% of all musculoskeletal injuries. PURPOSE: We systematically reviewed and critiqued the evidence regarding risk factors associated with increased risk of lower extremity stress fractures in runners. STUDY DESIGN: Systematic review. METHODS: A systematic, computerised literature search of Medline, Embase, PubMed, SPORTDiscus, and CINAHL databases (from database inception through 9 January 2014) using keywords related to risk factors and stress fractures. This systematic review with meta-analysis utilised the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for the search and reporting phases of the study. Inverse variance meta-analyses, using a random effects model were used to summarise ORs. RESULTS: 8 articles met the inclusion criteria; 7 were considered low risk. 4 articles qualified for meta-analysis. Results of the meta-analysis identified previous history of stress fracture and female sex as the primary risk factors for future stress fracture with a pooled OR of 4.99 (95% CI 2.91 to 8.56; p<0.001; I(2)=0%) and 2.31 (95% CI 1.24 to 4.29; p<0.01; I(2)=0%), respectively. CONCLUSIONS: Currently, only previous history of stress fracture and female sex are risk factors for lower extremity stress fractures strongly supported by the data.

The Effects of Pre-Exercise Ginger Supplementation on Muscle Damage and Delayed Onset Muscle Soreness.

Ginger possesses analgesic and pharmacological properties mimicking non-steroidal antiinflammatory drugs. We aimed to determine if ginger supplementation is efficacious for attenuating muscle damage and delayed onset muscle soreness (DOMS) following high-intensity resistance exercise. Following a 5-day supplementation period of placebo or 4 g ginger (randomized groups), 20 non-weight trained participants performed a high-intensity elbow flexor eccentric exercise protocol to induce muscle damage. Markers associated with muscle damage and DOMS were repeatedly measured before supplementation and for 4 days following the exercise protocol. Repeated measures analysis of variance revealed one repetition maximum lift decreased significantly 24 h post-exercise in both groups (p < 0.005), improved 48 h post-exercise only in the ginger group (p = 0.002), and improved at 72 (p = 0.021) and 96 h (p = 0.044) only in the placebo group. Blood creatine kinase significantly increased for both groups (p = 0.015) but continued to increase only in the ginger group 72 (p = 0.006) and 96 h (p = 0.027) post-exercise. Visual analog scale of pain was significantly elevated following eccentric exercise (p < 0.001) and was not influenced by ginger. In conclusion, 4 g of ginger supplementation may be used to accelerate recovery of muscle strength following intense exercise but does not influence indicators of muscle damage or DOMS.

The effect of increased physical activity on pulmonary diffusing capacity in unfit women.

The purpose of the study was to determine whether short-term high-intensity aerobic interval training improves resting pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO). Twenty-eight sedentary women [mean (SD) age 32 (11) years, body mass index 24.3 (5.7) kg m(-2)] were randomly assigned to either a self-directed moderate-intensity physical activity (n = 14) group or a supervised high-intensity aerobic interval training group (n = 14). The moderate physical activity group and the aerobic interval training group increased weekly physical activity energy expenditure by 800 and 1600 kcal week(-1), respectively. After 6 weeks, aerobic capacity increased to a similar exent in both groups (mean improvement 8%, effect size 0.39). The DLNO, but not DLCO, increased to a similar extent in both groups, by 4% or 3.0 (5.7) [95% confidence interval 0.8, 5.2] ml min(-1) mmHg(-1) m(-2) from pre- to post-training (effect size 0.27). There was no correlation between the change in aerobic capacity and the change in DLNO (P > 0.05) or between the change in aerobic capacity and the change in total weekly physical activity energy expenditure (P > 0.05). Interval training does not provide additional improvements in DLNO or aerobic capacity compared with self-directed moderate-intensity physical activity (4-6 metabolic equivalent tasks, 800 kcal week(-1), for 6 weeks) in unfit women. Despite the slight improvement in both DLNO and aerobic capacity, true meaningful physiological changes in these parameters remain questionable.

Enhancing the delivery of resveratrol in humans: if low bioavailability is the problem, what is the solution?

Resveratrol has emerged as a leading candidate for improving healthspan through potentially slowing the aging process and preventing chronic diseases. The poor bioavailability of resveratrol in humans has been a major concern for translating basic science findings into clinical utility. Although a number of positive findings have emerged from human clinical trials, there remain many conflicting results, which may partially be attributed to the dosing protocols used. A number of theoretical solutions have been developed to improve the bioavailability of resveratrol, including consumption with various foods, micronized powders, combining it with additional phytochemicals, controlled release devices, and nanotechnological formulations. While laboratory models indicate these approaches all have potential to improve bioavailability of resveratrol and optimize its clinical utility, there is surprisingly very little data regarding the bioavailability of resveratrol in humans. If bioavailability is indeed a limitation in the clinical utility of resveratrol, there is a need to further explore methods to optimize bioavailability in humans. This review summarizes the current bioavailability data, focusing on data from humans, and provides suggested directions for future research in this realm.

Mpox and Monkeypox Virus: Special Considerations for Athletes in Contact Sports.

Monkeypox virus infections (mpox) in humans have become increasingly common since the virus was first identified in 1970. Coverage of the ongoing mpox outbreak has emphasized the role of skin-to-skin contact in monkeypox virus transmission and has focused on the community of men who have sex with men. While close contact from sexual activity is currently the main mechanism of monkeypox virus transmission, the potential for contact sports to exacerbate the 2022 outbreak has largely been overlooked. Infectious diseases rapidly spread in sports with significant skin-to-skin contact (i.e., wrestling and other combat sports, American football, and rugby). Mpox has not yet reached the athletic community, but once it does, it may follow a similar pattern of other infectious skin diseases in sports. Thus, it is critical to initiate a discussion of the risk of mpox and potential preventive measures within a sports context. This Current Opinion aims to provide stakeholders within the sports community with a brief review of infectious skin diseases in athletes, an overview of mpox and why it is relevant to athletes, and recommendations to reduce the risk of monkeypox virus transmission within sports settings. Guidelines for sports participation in athletes exposed to mpox and those with suspected, probable, and confirmed cases of monkeypox are provided.

Premature Death in Bodybuilders: What Do We Know?

Premature deaths in bodybuilders regularly make headlines and are cited as evidence that bodybuilding is a dangerous activity. A wealth of research has revealed elite athletes typically enjoy lower mortality rates than non-athletes, but research on bodybuilder lifespan is surprisingly limited. Anabolic androgenic steroid (AAS) use is commonly cited as a key contributor to morbidity and premature mortality in bodybuilders, but this area of research is highly nuanced and influenced by numerous confounders unique to bodybuilding. It is quite possible that bodybuilders are at elevated risk and that AAS use is the primary reason for this, but there remains much unknown in this realm. As global participation in bodybuilding increases, and healthcare providers play a more active role in monitoring bodybuilder health, there is a need to identify how numerous factors associated with bodybuilding ultimately influence short- and long-term health and mortality rate. In this Current Opinion, we discuss what is currently known about the bodybuilder lifespan, identify the nuances of the literature regarding bodybuilder health and AAS use, and provide recommendations for future research on this topic.