The physical demands of exploration mission tasks, like any job, can vary depending on the task and environment. During the original Apollo missions certain tasks like photography needed little effort whereas construction and shoveling type tasks required increased physical exertion. Planned missions to terrestrial surfaces (e.g., asteroid, the moon, and Mars), where crewmembers will spend an extended period of time in a microgravity setting, may result in a plausible scenario in which at some point within the mission critical tasks may become physically challenging enough that a decrease in performance and safety results. Therefore, it is critical to understand the relationship between the ability to complete specific mission critical tasks and aerobic exercise capacity. To mitigate the risk of an unacceptable scenario in which crewmembers are unable to perform critical mission tasks due to inadequate aerobic exercise capacity, a set of easily administered predictor tests must be developed and used to evaluate both countermeasure effectiveness and ultimately, whether a crewmember is ready and capable of performing various physiologically demanding tasks. Therefore, the overall goal of this proposed work is twofold: develop a thorough understanding of the physiological parameters associated with the ability to complete simulated mission critical tasks, and develop a battery of predictor tests that will provide critical information regarding a crewmember’s readiness and capability to perform these tasks.
This study had the following specific aims:
- Determine values and ranges for aerobic fitness variables that can individually or in aggregate (a) map to the level of success for a given mission critical task and (b) provide an aerobic fitness standard.
- Using the information obtained from Specific Aim 1, design predictor testing protocols that can be performed with in-flight hardware and astronaut time constraints.
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Investigators studied a group of 45 men and women who completed a series of mission critical tasks; a surface traverse task and a hill climb task. Participants performed each mission task at a low and moderate intensity designed to elicit specific metabolic responses similar to what is expected for ambulation in Lunar and Martian gravities, respectively. Aerobic fitness was characterized via cycling and rowing VO2peak, ventilatory threshold (VT), and critical power. Logistic regression and receiver operating characteristic (ROC) curve analysis were used to determine the cutoff thresholds for each aerobic fitness parameter that accurately predicted task performance.
Fifteen participants volunteered for this study. VO2peak and peak power output (PPO) were determined on cycle and rowing ergometers. Critical power (CP) was determined by a three minute all-out rowing test. Subjects then performed an emergency capsule egress on a mock-up of NASA’s Orion space capsule. Peak metabolic data were compared between the cycling and rowing tests. Pearson’s Correlation was used to identify relationships between egress time and VO2peak, PPO, and CP.
The low and moderate intensity traverse tests estimated a VO2 response of 23±1 ml kg-1 min-1 and 29±1 ml kg-1 min-1. VO2peak, VT, and critical power all showed high sensitivity and specificity for identifying individuals who could not complete the mission tasks. Therefore, minimum fitness thresholds for each task at each intensity were determined for each of the submaximal and maximal fitness variables. In summary, investigators identified aerobic fitness thresholds below which task performance was impaired for both low and moderate intensity mission critical tasks. Specifically, cycling VO2peak, VT, and rowing CP could each be used to predict task failure.
VO2peak, VCO2peak, and minute ventilation were not different between cycling and rowing tests. Cycling elicited a greater PPO than the rowing test. Egress time was negatively correlated to cycling and rowing VO2peak (r=-0.61) and cycling and rowing PPO (r=-0.56 and r=-0.74, respectively), but not CP. Conclusions: Our data suggest that rowing PPO/kg was a strong predictor of egress time. Although individuals with higher PPO/kg were able to finish the task in less time, even sedentary individuals with low fitness levels (VO2peak<20 ml/kg/min) were able to complete the egress within two minutes. This suggests that if minimum fitness is maintained, completing the emergency egress should be successful.
Sutterfield SL, Alexander AM, Hammer SM, Didier KD, Caldwell JT, Barstow TJ, and Ade CJ. "
Prediction of planetary mission task performance for long-duration spaceflight. Medicine and Science in Sports Exercise.
2019. August; 51(8):1662-70. [DOI]
Alexander AM, Sutterfield SL, Kriss KN, Hammer SM, Didier KD, Cauldwell JT, Dzewaltowski AC, Barstow TJ, and Ade CJ. Prediction of emergency capsule egress performance. Aerospace Medicine and Human Performance.
2019. September 1;90(9):782-7. [DOI]
Crew health and performance is critical to successful human exploration beyond low Earth orbit.
The Human Research Program (HRP) investigates and mitigates the highest risks to human health
and performance, providing essential countermeasures and technologies for human space exploration.
Risks include physiological and performance effects from hazards such as radiation, altered gravity,
and hostile environments, as well as unique challenges in medical support, human factors,
and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify
the approach and research activities planned to address these risks, which are assigned to specific
Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.
The Human Research Roadmap is located at: https://humanresearchroadmap.nasa.gov/
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