Kipp, Shalaya

Abstract On average, females have smaller airways than males. The largest discrepancy in airway size occurs during puberty, when endogenous sex hormone concentrations diverge between males and females. Transgender individuals often use gender‐affirming hormone therapy (GAHT) to align physical characteristics with gender identity. It is unknown whether GAHT influences airway size (luminal area and length). We evaluated the large conducting airways before starting GAHT and while undergoing years of GAHT. This retrospective within‐subject study included 12 adult transgender individuals who underwent CT scanning before starting GAHT and again after ≥1 year of GAHT. For each transgender individual, we identified two matched cisgender controls (one male and one female) who also underwent two CT scans over a comparable time interval for longitudinal comparison. We used a three‐dimensional reconstruction of CT imaging to measure luminal areas. Within‐subject changes in airway size between scans were assessed using Student's paired t ‐tests in transgender individuals undergoing feminizing hormone therapy. Variance between scans was assessed using Levene's test. Pre‐scans occurred an average of 2.0 ± 3.1 years before beginning GAHT. Transgender persons were on GAHT for an average of 3.3 ± 1.7 years (range, 1.0 – 6.7 years) at their second scan. We found no significant differences in airway luminal cross‐sectional areas for transgender persons on feminizing hormone therapy. The variance in airway size change between scans was not statistically different between transgender individuals and control subjects. Our findings suggest that the size of large conducting airways might remain unchanged after a period (>1 year) on GAHT.

In this short report, we detail new data on the upper limits of human energy expenditure (9.6 times basal metabolic rate) and water turnover (10.5 L·12 h −1 ) during continuous single-day exercise in the cold. Our results indicated elevated energy use, and impressively, water turnover comparable to exercise in warmer conditions. These findings have implications for training and endurance performance of strenuous exercise in cold weather environments.

This study leverages an experiment of nature framework to examine sex-based differences in ultraendurance swimming using English Channel performance data. Males were faster than females, with the greatest differences observed among older swimmers and top performers. Performance was optimal in moderately cool water temperatures (17–18°C). These findings highlight how naturally occurring endurance events provide unique opportunities to study physiological limits and the combined influences of sex, age, and environment on human performance.

There is a context-dependent trade-off in body size of elite runners, such that smaller body sizes are observed among longer distance runners. However, it is unclear whether this trade-off in body size is observed in other Olympic sports, such as cycling and swimming. To understand the association between body size and athletic competition, we examined metrics of body size from male and female Olympic athletes competing in swimming, running, and cycling. We collected standard anthropometrics (height, mass, body mass index (BMI), and body surface area) of elite male and female athletes competing in the London 2012 Summer Olympics from a public repository. Anthropometric data were compared between sexes (male and female); between sports (swimming, running, and cycling); and between distances within sports (shorter and longer distance). Males were taller ( P < 0.001), heavier ( P < 0.001), and had a larger BMI ( P < 0.001) compared to females. Relative to athletes competing in longer distance events, athletes competing in shorter distance were generally taller (running: P < 0.001, swimming: P ≤ 0.014) and heavier (running: P < 0.001, swimming: P = 0.002 (males) and P = 0.148 (females), cycling: P < 0.001) for both males and females. Height was not different between shorter and longer distance cyclists. There was a trade-off between body size and distance for each of the three Olympics sports, such that smaller athletes were observed in longer distance events. Although there were large sex-based differences in body size, similar trade-offs in size and event were observed for both males and females. These data suggest that there is an optimal combination of skeletal muscle mass and body size to optimize movement economy that is generally preserved across different modes of human locomotion.

In 2023, Faith Kipyegon set the female world record for running one mile (4:07.64). Here, we quantitatively explore if improved aerodynamic drafting could allow her to run just 3.19% faster and thus break the 4-minute mile barrier. Drafting involves other athletes (pacers) running in formation around a designated athlete to reduce the aerodynamic drag force acting on the designated runner. Drafting allows the designated athlete to run faster at the same rate of metabolic energy consumption. Our overall approach was to estimate Kipyegon’s metabolic energy consumption during her mile world record performance. Then, we used empirically established relationships between horizontal resistive force, running velocity and metabolic power to estimate how much faster she could run at the same metabolic power if the aerodynamic force was reduced via drafting. Our calculations suggest that Kipyegon could run ~3:59.37 with drafting provided by one pacer in front and one in back who change out with two other pacers at 800 m.

Abstract Females likely experience larger performance benefits from androgenic‐anabolic steroids than males. We set out to determine if there were temporal differences in select athletics (track and field) records between females and males. Exploratory aims included: (1) evaluating the improvements in female and male world records over time, and (2) investigating the influence of doping programs on male and female world records before and after 1990, when sports governing bodies began to implement random out‐of‐competition and systematic in‐competition drug testing. We collected the top 500 performances of all time for both sexes from an online database (worldathletics.org) in four running events (100, 200, 400 and 800 m) and two throwing events (discus throw and shot‐put). Data were stratified into quintiles based on world record ranking (1st to 100th, 101st to 200th, etc.). The temporal distribution of the top 100 female performers was significantly earlier than the top 100 male performers (year: 2000 ± 1 vs. 2005 ± 1, respectively; P < 0.0001). Within the event, the top performances occurred significantly earlier for females in the 800 m (year: 1995 ± 15 vs. 2003 ± 12; P = 0.0007) and shot‐put (year: 1992 ± 14 vs. 2003 ± 17; P = 0.0004). Among females, world records rapidly improved through the 1980s, but following 1990, the world records ceased to improve. Geographically, there was a greater representation of countries with state‐sponsored doping programs, specifically among female performances. We postulate these sex differences in the temporal distribution of top performances are likely associated with enhanced effectiveness of exogenous androgens (steroid doping) among female athletes with lower endogenous androgen hormones compared to males.