Clayburn, Andrew J.

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.

Hypoxia exacerbates fatigue via central mechanisms after ischemic single-leg exercise. The greater fatigue observed during ischemic dynamic fatiguing exercise with hypoxia inspirate did not differ between the sexes. Hypoxia-induced central limitations are present in acute ischemic exercise and do not appear different in males and females.

Purpose: The present work was performed to provide an updated and comprehensive systematic review and meta-analysis on the potential ergogenic effects associated with ischemic preconditioning (IPC). In this context, this systematic review and meta-analysis aimed to determine the magnitude of the potential ergogenic effect of IPC and the influence of descriptive factors that contribute to the variability of its potential ergogenic effect. We hypothesized that IPC would be associated with improved exercise performance, and putative factors would modulate this association. Methods: On October 17, 2022, a systematic search of three databases (PubMed, Scopus, and Web of Science) was performed. The electronic search yielded 2,876 unique records, of which 79 were included in analyses after abstract and full-text screening. Eligible study designs included within subjects cross-over, sham controlled study, with a randomized or counter balanced study design. Prespecified analyses aimed to determine whether the ergogenic effect of IPC is influenced by: 1) exercise parameters (type of exercise, fraction of inspired oxygen, and muscle group(s) involved in exercise) and 2) IPC parameters (dosage, duration, and timing before onset of exercise). Results: The meta-analysis model demonstrated that exercise performance was improved with IPC compared to the sham control (pooled standard paired difference (SPD), 0.156; 95% confidence interval (CI), 0.084 to 0.227; Z = 4.258; P < 0.001; n = 105). Both remote IPC (pooled SPD, 0.219; 95% CI, 0.071 to 0.368; Z = 2.894; P = 0.004) and local IPC (pooled SPD, 0.159; 95% CI, 0.088 to 0.231; Z = 4.386; P < 0.001) demonstrated ergogenic effects on performance. Subgroup analyses based on the fraction of inspired oxygen level revealed improved exercise performance in normoxic (pooled SPD, 0.169; 95% CI, 0.100 to 0.237; Z = 4.805; P < 0.001) but not hypoxic (pooled SPD, 0.160; 95% CI, -0.029 to 0.349; Z = 1.659; P = 0.097) conditions. The most notable improvement in exercise performance following IPC was demonstrated during cycling (pooled SPD, 0.116; 95% CI, 0.023 to 0.209; Z = 2.454; P = 0.014), running (pooled SPD, 0.180; 95% CI, 0.056 to 0.303; Z = 2.847; P = 0.004), and leg press (pooled SPD, 0.421; 95% CI, 0.034 to 0.808; Z = 2.131; P = 0.033) performance tests. Conclusion: Overall, IPC demonstrated a clear ergogenic effect on exercise performance across various exercise modalities under normoxic environmental conditions. The enhanced exercise performance following IPC was most pronounced in aerobic tests of performance which predominantly recruited large muscle groups in the lower extremities: cycling, running, and leg press. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The timing and magnitude of sex differences in athletic performance during early human development, prior to adulthood, is unknown. Objective To compare swimming velocity of boys and girls for all Olympic‐length freestyle swimming events to determine the age of divergence in swimming performance. Methods We collected the all‐time top 100 U.S. freestyle swimming performance times of boys and girls age 5 to 18 years for the 50m to 1500m events. Results Swimming performance improved with increasing age for boys and girls ( p <0.001) until reaching a plateau, which initiated at a younger age for girls (15 years) than boys (17 years; sex×age; p <0.001). Prior to age 10, the top 5 swimming records for girls were 3% faster than the top boys ( p <0.001). For the 10 th –50 th places, however, there were no sex‐related differences in swimming performance prior to age 10 ( p =0.227). For both the top 5 and 10 th –50 th places, the sex difference in performance increased from age 10 (top 5, 2.5%; 10 th –50 th places, 1.0%) until age 17 (top 5, 7.6%; 10 th –50 th places, 8.0%). For all places, the sex difference in performance at age 18 was larger for sprint events (9.6%; 50–200m) than endurance events (7.1%; 400–1500m; p <0.001). Additionally, the sex‐related difference in performance increased across age and US ranking from 2.4% for 1 st place to 4.3% for 100 th place ( p <0.001), indicating less depth of performance in girls than boys. However, annual participation was ~20% higher in girls than boys for all ages ( p <0.001). Conclusion The top 5 girls demonstrated faster swimming velocities and the 10 th –50 th place girls demonstrated similar swimming velocities than boys (until ~10 years). After age 10, however, boys demonstrated increasingly faster swimming velocities than girls until 17 years. Collectively, these data suggest girls are faster, or at least not slower, than boys prior to the performance‐enhancing effects of puberty. Support or Funding Information This study was supported by the National Institutes of Health R‐35‐HL139854‐02 (MJJ), HL139854‐02S1 (AJC), 5T32DK007352‐40 (JWS), and the Mayo Foundation. Elite swimming performance. Mean swimming velocity from 5 to 18 years of the top 100 fastest US boys (blue circles) and girls (red triangles) for the 50, 100, 200, 400, 800 and 1500m freestyle swimming distances. Figure 1 Sex differences in performance of the top 5 places. The primary plot (heat map) displays the sex differences in swimming velocity (% boy’s swimming velocity) of the top 5 US rankings in each freestyle event distance and age, negative values (red) indicate faster performance of girls. The top displays the mean sex difference across age, and the right plot displays the mean sex difference across swimming event distance. Figure 2