[Paper Review] Space Physiology and Technology: Musculoskeletal Adaptations, Countermeasures, and Opportunities for Wearable Systems

Shamas U.E. Khan, Rejin John Varghese+3 more|arXiv (Cornell University)|Apr 4, 2024

Spaceflight effects on biologyMedicine3 citations

TL;DR

This paper reviews musculoskeletal adaptations in microgravity, emphasizing bone loss and muscle atrophy in astronauts, and proposes wearable robotic systems—particularly exoskeletons and exosuits—as next-generation countermeasures. By integrating real-time sensing, adaptive control, and personalized support, these technologies offer a dynamic alternative to traditional exercise regimens, with potential applications in space and terrestrial healthcare.

ABSTRACT

Space poses significant challenges for humans, leading to physiological adaptations in response to an environment vastly different from Earth. A comprehensive understanding of these physiological adaptations is needed to devise effective countermeasures to support human life in space. This narrative review first focuses on the impact of the environment in space on the musculoskeletal system. It highlights the complex interplay between bone and muscle adaptations and their implications on astronaut health. Despite advances in current countermeasures, such as resistive exercise and pharmacological interventions, they remain partially effective, bulky, and resource-intensive, posing challenges for future missions aboard compact spacecraft. This review proposes wearable sensing and robotic technology as a promising alternative to overcome these limitations. Wearable systems, such as sensor-integrated suits and (soft) exoskeletons, can provide real-time monitoring, dynamic loading, and exercise protocols tailored to individual needs. These systems are lightweight, modular, and capable of operating in confined environments, making them ideal for long-duration missions. In addition to space applications, wearable technologies hold significant promise for terrestrial uses, supporting rehabilitation and assistance for the ageing population, individuals with musculoskeletal disorders, and enhance physical performance in healthy users. By integrating advanced materials, sensors and actuators, and intelligent and energy-efficient control, these technologies can bridge gaps in current countermeasures while offering broader applications on Earth.

Motivation & Objective

• To analyze the physiological impacts of microgravity on the human musculoskeletal system, including bone resorption and muscle atrophy.
• To evaluate current countermeasures used by space agencies and identify their limitations in long-duration missions.
• To propose wearable robotic and sensing technologies as a transformative alternative to exercise-based countermeasures.
• To highlight the potential of personalized, AI-driven exoskeletons for real-time physiological support in space.
• To advocate for standardized, international data collection to improve longitudinal understanding of space-related health effects.

Proposed method

• Systematic review of physiological adaptations in microgravity, focusing on mechanotransduction pathways and bone-muscle crosstalk.
• Analysis of existing countermeasures, including resistance and aerobic exercise regimens, used on the International Space Station.
• Evaluation of wearable robotics, including exoskeletons and exosuits, with integrated sensing and feedback systems for real-time monitoring.
• Integration of AI-driven adaptive control algorithms to personalize support based on individual astronaut physiology and activity levels.
• Assessment of material science and radiation-hardened electronics for durability and functionality in space environments.
• Proposal for a centralized, international space health database to harmonize data collection and improve research comparability.

Experimental results

Research questions

• RQ1 How do microgravity-induced mechanical unloading and fluid shifts lead to bone resorption and muscle atrophy in astronauts?
• RQ2 To what extent do current exercise-based countermeasures mitigate musculoskeletal deconditioning during long-duration spaceflight?
• RQ3 Can wearable robotic systems provide more effective, personalized, and adaptive support than traditional exercise protocols?
• RQ4 What are the key technological and environmental challenges in deploying wearable robotics in space, including radiation and sensor durability?
• RQ5 How can standardized, global data frameworks improve the reliability and generalizability of space physiology research?

Key findings

• Muscle atrophy of up to 16% and bone resorption at a rate of 1–2% per month occur during prolonged microgravity exposure, even with current countermeasures.
• Post-flight rehabilitation is often required due to persistent deconditioning, with physiological changes resembling accelerated aging on Earth.
• Wearable robotics, particularly AI-integrated exoskeletons, offer dynamic, personalized support that can adapt to real-time physiological demands.
• Current research is limited by short-duration missions, inconsistent methodologies, and a lack of gender diversity, especially underrepresentation of female participants.
• The integration of advanced materials, radiation-hardened electronics, and real-time sensing is essential for reliable deployment of wearable systems in space.
• A centralized, international space health database is critical to harmonize data, improve statistical power, and enable longitudinal analysis across missions.