Negative impact of disuse and unloading on tendon enthesis structure and function

Area of Science:

• Space medicine
• Musculoskeletal research
• Biomechanics

Background:

• Spaceflight causes skeletal muscle disuse and unloading, leading to deconditioning and bone remodeling.
• Tendons, crucial for force transmission, are also impacted by reduced mechanical load.
• Existing reviews primarily address muscle and bone changes, with limited focus on tendon entheses.

Purpose of the Study:

• To review the relationship between mechanical stress and tendon enthesis structure and composition.
• To examine the detrimental effects of skeletal muscle disuse and unloading on enthesis health.
• To discuss the implications of enthesis remodeling for astronaut health and potential risks.

Main Methods:

• Literature review of studies on mechanical loading and enthesis.
• Analysis of research on skeletal muscle disuse and unloading effects on entheses.
• Discussion of enthesis plasticity and remodeling in the context of spaceflight.

Main Results:

• Enthesis structure and composition are significantly influenced by tensile and compressive loads.
• Skeletal muscle disuse and unloading negatively impact enthesis structure, composition, and function.
• Spaceflight-induced enthesis remodeling may compromise its ability to withstand stress, increasing weakness.

Conclusions:

• Altered compressive strength at tendon entheses poses a risk for astronauts.
• Enthesopathies may develop due to compromised enthesis integrity in microgravity.
• Further research is needed to understand and mitigate enthesis-related risks during space missions.