Human Research Program Human Health Countermeasures Element Cardiovascular Risks Standing Review Panel (SRP)

The Cardiovascular Risk Standing Review Panel (SRP) evaluated several cardiovascular risks associated with space flight along with the ongoing and emerging plans to study these issues and potentially propose and/or develop countermeasures. The areas of focus included: 1) The risk of cardiac rhythm problems during prolonged space flight, and 2) Issues related to the risk of orthostatic intolerance during re-exposure to gravity. An emerging area of concern is radiation associated vascular injury. The risk of cardiac rhythm disturbances has emerged based on case reports only. No systematic study of this risk has been published. However, concerns about this risk are heightened by the age range of astronauts, the structural changes in the heart that occur during space flight, and the potential shifts in fluids and electrolytes. The current plan is to use prolonged Holter monitor EKG records made as part of the "Integrated Cardiovascular SMO" in space to determine more about the frequency and magnitude of this problem and to link this data to complementary data from the nutrition group on electrolytes. The SRP was supportive of this approach. The SRP also felt that any data related to cardiovascular risk in space should be better coordinated with the medical screening data that all astronauts undergo at regular intervals. Additionally, while there are potential privacy issues related to this suggestion, many of the current barriers to better coordination of experimental and clinical data appear to reflect longstanding cultural traditions at NASA that need rethinking. The risk of orthostatic intolerance during re-exposure to gravity was seen by the SRP as an area supported by a wealth of published physiological evidence. The SRP also felt that moving forward with the planned approach to countermeasures was reasonable and that extensive additional hypothesis testing on the physiology of orthostatic intolerance was not needed at this time. There was support for developing ground based models of limited (e.g. 1/6 th) G environments on Earth that generated a number of ideas for consideration by NASA investigators

Sex Differences in Elite Swimming with Advanced Age Are Less Than Marathon Running

The sex difference in marathon performance increases with finishing place and age of the runner but whether this occurs among swimmers is unknown. The purpose was to compare sex differences in swimming velocity across world record place (1st–10th), age group (25–89 years), and event distance. We also compared sex differences between freestyle swimming and marathon running. The world\u27s top 10 swimming times of both sexes for World Championship freestyle stroke, backstroke, breaststroke, and butterfly events and the world\u27s top 10 marathon times in 5-year age groups were obtained. Men were faster than women for freestyle (12.4 ± 4.2%), backstroke (12.8 ± 3.0%), and breaststroke (14.5 ± 3.2%), with the greatest sex differences for butterfly (16.7 ± 5.5%). The sex difference in swimming velocity increased across world record place for freestyle (P \u3c 0.001), breaststroke, and butterfly for all age groups and distances (P  \u3c 0.001) because of a greater relative drop-off between first and 10th place for women. The sex difference in marathon running increased with the world record place and the sex difference for marathon running was greater than for swimming (P \u3c 0.001). The sex difference in swimming increased with world record place and age, but was less than for marathon running. Collectively, these results suggest more depth in women\u27s swimming than marathon running

Men Are More Likely than Women to Slow in the Marathon

Studies on nonelite distance runners suggest that men are more likely than women to slow their pace in a marathon. Purpose: This study determined the reliability of the sex difference in pacing across many marathons and after adjusting women\u27s performances by 12% to address men\u27s greater maximal oxygen uptake and also incorporating information on racing experience. Methods: Data were acquired from 14 US marathons in 2011 and encompassed 91,929 performances. For 2929 runners, we obtained experience data from a race-aggregating Web site. We operationalized pace maintenance as the percentage change in pace observed in the second half of the marathon relative to the first half. Pace maintenance was analyzed as a continuous variable and as two categorical variables, as follows: maintain the pace, defined as slowing=30%. Results: The mean change in pace was 15.6% and 11.7% for men and women, respectively (P \u3c 0.0001). This sex difference was significant for all 14 marathons. The odds for women were 1.46 (95% confidence interval, 1.41–1.50; P \u3c 0.0001) times higher than men to maintain the pace and 0.36 (95% confidence interval, 0.34–0.38; P \u3c 0.0001) times that of men to exhibit marked slowing. Slower finishing times were associated with greater slowing, especially in men (interaction, P \u3c 0.0001). However, the sex difference in pacing occurred across age and finishing time groups. Making the 12% adjustment to women’s performances lessened the magnitude of the sex difference in pacing but not its occurrence. Although greater experience was associated with less slowing, controlling for the experience variables did not eliminate the sex difference in pacing. Conclusions: The sex difference in pacing is robust. It may reflect sex differences in physiology, decision making, or both

The Two-hour Marathon: What\u27s the Equivalent for Women?

The principal characteristic of the runner who may break the two-hour barrier in the marathon will be their sex: the person will be male. The fastest men outperform the fastest women because of sex differences in physiology including a higher VȮ2 max. This viewpoint addresses the questions of what is the two-hour equivalent for women, and who will break this barrier? The current sex difference in the world record for the marathon is ~10% which is slightly less than the mean sex difference in performance usually documented between elite men and women distance runners. Based on comparisons of the top 50 marathon times run by men and women, we argue that Paula Radcliffe\u27s world record of 2:15:25 (hr:min:s) set in 2003 is at least equivalent to a two-hour marathon for women. We also provide evidence that there is less depth in elite women\u27s distance running, in part, due to historical and social factors that have led to less opportunity for women than men

Simple Bodyweight Training Improves Cardiorespiratory Fitness With Minimal Time Commitment: A Contemporary Application of the 5BX Approach

International Journal of Exercise Science 14(3): 93-100, 2021. Bodyweight training (BWT) is a style of interval exercise based on classic principles of physical education. Limited research, however, has examined the efficacy of BWT on cardiorespiratory fitness. This is especially true for simple BWT protocols that do not require extraordinarily high levels of effort. We examined the effect of a BWT protocol, modelled after the original “Five Basic Exercises” (5BX) plan, on peak oxygen uptake (VO2peak) in healthy, inactive adults (20 ± 1 y; body mass index: 20 ± 5 kg/m2; mean ± SD). Participants were randomized to a training group that performed 18 sessions over six weeks (n=9), or a non-training control group (n = 10). The 11-minute session involved five exercises (burpees, high knees, split squat jumps, high knees, squat jumps), each performed for 60-seconds at a self-selected “challenging” pace, interspersed with active recovery periods (walking). Mean intensity during training was 82 ± 5% of maximal heart rate, rating of perceived exertion was 14 ± 3 out of 20, and compliance was 100%. ANCOVA revealed a significant difference between groups after the intervention, such that VO2peak was higher in the training group compared to control (34.2 ± 6.4 vs 30.3 ± 11.1 ml/kg/min; p = 0.03). Peak power output during the VO2peak test was also higher after training compared to control (211 ± 43 vs 191 ±50 W, p = 0.004). There were no changes in leg muscular endurance, handgrip strength or vertical jump height in either group. We conclude that simple BWT— requiring minimal time commitment and no specialized equipment — can enhance cardiorespiratory fitness in inactive adults. These findings have relevance for individuals seeking practical, time-efficient approaches to exercise