"Tighter fit" theory-physiologists explain why "higher altitude" and jugular occlusion are unlikely to reduce risks for sports concussion and brain injuries

Limitations of Separating Athletes into High or Low-Risk Groups based on a Cut-Off. A Clinical Commentary

Background

Athlete injury risk assessment and management is an important, yet challenging task for sport and exercise medicine professionals. A common approach to injury risk screening is to stratify athletes into risk groups based on their performance on a test relative to a cut-off threshold. However, one potential reason for ineffective injury prevention efforts is the over-reliance on identifying these 'at-risk' groups using arbitrary cut-offs for these tests and measures. The purpose of this commentary is to discuss the conceptual and technical issues related to the use of a cut-off in both research and clinical practice.

Clinical Question

How can we better assess and interpret clinical tests or measures to enable a more effective injury risk assessment in athletes?

Key Results

Cut-offs typically lack strong biologic plausibility to support them; and are typically derived in a data-driven manner and thus not generalizable to other samples. When a cut-off is used in analyses, information is lost, leading to potentially misleading results and less accurate injury risk prediction. Dichotomizing a continuous variable using a cut-off should be avoided. Using continuous variables on its original scale is advantageous because information is not discarded, outcome prediction accuracy is not lost, and personalized medicine can be facilitated.

Clinical Application

Researchers and clinicians are encouraged to analyze and interpret the results of tests and measures using continuous variables and avoid relying on singular cut-offs to guide decisions. Injury risk can be predicted more accurately when using continuous variables in their natural form. A more accurate risk prediction will facilitate personalized approaches to injury risk mitigation and may lead to a decline in injury rates.

Level of Evidence

5.

From beaks to brains-Challenges in translating woodpecker biology into traumatic brain injury innovation

The biomechanics of woodpeckers have captivated researchers for decades. These birds' unique ability to withstand repeated impacts, seemingly without apparent harm, has piqued the interests of scientists and clinicians across multiple disciplines. Historical and recent studies have dissected the anatomical and physiological underpinnings of woodpeckers' protective mechanisms and sparked interest in the development of woodpecker-inspired safety equipment. Despite the intuitive appeal of translating woodpecker adaptations into strategies for human traumatic brain injury (TBI) prevention, significant challenges hinder such innovation. Critical examinations reveal a lack of direct applicability of these findings to human TBI prevention, attributed to fundamental biological and mechanical dissimilarities between humans and woodpeckers. Additionally, some commercial endeavors attempting to capitalize on our fascination with woodpeckers are rooted in unsubstantiated claims about these birds. This paper explores the narrative surrounding woodpecker biomimicry, including its origins and history, and highlights the challenges of translating findings from unconventional animal models of TBI into effective human medical interventions.

Bad Altitude: Categorizing Elevation Produces Spurious Association With Concussions in the National Football League (NFL)

OBJECTIVE: To assess whether prior analyses, where there was a relationship between altitude and concussion rates in American football, would replicate using a larger data set and altitude as a continuous variable. DESIGN: Cohort study replication. METHODS: We analyzed data from all NFL regular season games from 2012-2019. Concussions were identified from public databases and NFL injury reports. The altitude of each stadium was identified using mapping software. Concussion rates were calculated for each stadium and plotted against continuous altitude. We calculated crude rate ratios for several categorical cut points and used logistic and Poisson regression models to assess associations with continuous altitudes. RESULTS: We identified 867 players (1103 player seasons) who sustained 1159 concussions during the time period 2012-2019. All continuous plots and models showed no evidence of any association between concussions and altitude. A Poisson model found an IRR of 1.00 (95% CI, 0.99-1.01) for every 100-ft increase in altitude. A 644-ft cut point (used in previous studies) produced a significant difference (incidence rate ratio [IRR], 0.71; 95% CI, 0.54-0.94) in 2012-2013, but this did not replicate in 2014-2019 (IRR, 0.99; 95% CI, 0.84-1.14). CONCLUSION: We found no association between altitude and concussion rates in the NFL when altitude was analyzed continuously rather than inappropriately categorized. Our findings should increase skepticism of any effect of altitude on concussions at the elevations at which most American football is played, as well as clinical interventions based on that theory. It also underscores the importance of keeping continuous variables continuous wherever possible. J Orthop Sports Phys Ther 2022;52(10):694-701. Epub: 27 July 2022. doi:10.2519/jospt.2022.11220.

Evidence of traumatic brain injury in headbutting bovids

Traumatic brain injury (TBI) is a leading cause of neurologic impairment and death that remains poorly understood. Rodent models have yet to produce clinical therapies, and the exploration of larger and more diverse models remains relatively scarce. We investigated the potential for brain injury after headbutting in two combative bovid species by assessing neuromorphology and neuropathology through immunohistochemistry and stereological quantification. Postmortem brains of muskoxen (Ovibos moschatus, n = 3) and bighorn sheep (Ovis canadensis, n = 4) were analyzed by high-resolution MRI and processed histologically for evidence of TBI. Exploratory histological protocols investigated potential abnormalities in neurons, microglia, and astrocytes in the prefrontal and parietal cortex. Phosphorylated tau protein, a TBI biomarker found in the cerebrospinal fluid and in neurodegenerative lesions, was used to detect possible cellular consequences of chronic or acute TBI. MRI revealed no abnormal neuropathological changes; however, high amounts of tau-immunoreactive neuritic thread clusters, neurites, and neurons were concentrated in the superficial layers of the neocortex, preferentially at the bottom of the sulci in the muskoxen and occasionally around blood vessels. Tau-immunoreactive lesions were rare in the bighorn sheep. Additionally, microglia and astrocytes showed no grouping around tau-immunoreactive cells in either species. Our preliminary findings indicate that muskoxen and possibly other headbutting bovids suffer from chronic or acute brain trauma and that the males' thicker skulls may protect them to a certain extent.

Consider the woodpecker: The contested more-than-human ethics of biomimetic technology and traumatic brain injury

Chronic Traumatic Encephalopathy, or CTE, is a neurodegenerative disease caused by traumatic brain injury and most frequently associated with contact sports such as American Football. Perhaps surprisingly, the woodpecker - an animal apparently immune to the effects of head impacts - has increasingly figured into debates surrounding CTE. On the one hand, the woodpecker is described as being contra-human and used to underscore the radical inappropriateness of humans playing football. On the other, there have been attempts to mitigate against the risk of CTE through the creation of biomimetic technologies inspired by woodpeckers. In this article I examine the highly politicized encounters between humans and woodpeckers and discuss how the politics of re-/dis-/en-tanglement during these interspecies relations is rendered meaningful. I show here, first, that those who seek to keep the human and the woodpecker apart envisage social overhaul while biomimetic technologies are put to work for the status quo. Second, I stress that different forms of entanglement have diverse sociopolitical consequences. I conclude by suggesting that the case of the woodpecker troubles a strand of contemporary scholarship in Science and Technology Studies that argues that biotechnologies are inherently transformatory and that foregrounding entanglement and interspecies relations is ethically generative. Instead, a discursive separation of nature and culture may be innovative.

The Effects of Altitude on Concussion Incidence in the 2013-2017 National Hockey League Seasons

Background and objective

The high incidence of traumatic brain injuries during contact sports has necessitated the need for further research pertaining to their implications and possible mitigation. Despite increasing attention to sports-related concussions, there is still a striking lack of detail pertaining to the environmental factors that contribute to their occurrence. One environmental condition that has yet to be considered is altitude. Altitude cannot be readily adjusted, yet can still impact quality of play and concussion incidence. The current body of published evidence evaluating environmental effects on concussion is divided on the degree to which altitude mitigates concussion incidence. We aim to systematically compare the prevalence of concussions that occur at high and low altitude utilizing 1000 feet (304.8 meters) as a cut-off marker for high altitude. Our research also takes a novel approach utilizing average games missed as a proxy for concussion severity. We hope to use this analysis to shed light on the implication of altitude on concussion incidence.

Methods

Individual player data on concussion incidence were retrospectively acquired for the 2013-2017 National Hockey League (NHL) seasons utilizing FOX Sports Injury tracker. NHL season schedules were acquired through the online source “Hockey Reference.” In order to establish cutoff criteria for high vs low altitude we adopted 1000 feet (304.8 meters) as high-low altitude cutoff. We also evaluated our data utilizing a previously published high-low altitude cutoff of 644 feet (196.3 meters). Specific altitudes of each NHL arena were derived from “elevationmap.net”. One caveat to our data collection was the striking lack of publicly available data pertaining to the concussions sustained by each NHL team. Data was analyzed utilizing SAS programing.

Results

Out of the 5281 games included in our data set, we documented a total of 133 concussions which occurred in 125 games through the 2013-2017 NHL seasons. We noted an increase in concussion reporting in the most recent 2016-2017 NHL season compared to the previous 2013-2016 seasons. Effect of altitude variance on concussion rate was evaluated utilizing 644 and 1000 ft as the low-high altitude split. We defined each variance by where the team is based at compared to where the game was played. This produced four distinct categories: 1) low-low altitude, 2) low-high altitude, 3) high-low altitude, and 4) high-high altitude. We noted a significant difference in concussion rate when teams based at high altitude above 1000 ft travel to play at low altitude; this trend was non-significant at 644 ft. The results of the average games missed analysis demonstrated that teams that play above 1000 feet had fewer games missed per concussion compared to teams that are based at a low altitude.

Conclusions

Though underreported in the total number of concussions in the 2013-2017 NHL seasons, our data suggests that teams who are based at a high altitude (>1000ft) experience a reduction in mean concussion rate when traveling to play at a lower altitude. Our data also indicated a reduction in average games missed post-concussion for teams based at a higher altitude. It is our goal that our findings here contribute to the larger discussion about concussion incidence and can be applied to other sports leagues and activities to mitigate their dangerous effects.

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.