Bisphosphonates as a supplement to exercise to protect bone during long-duration spaceflight

Area of Science:

• Space physiology
• Bone biology
• Pharmacology

Background:

• Long-duration spaceflight causes significant bone loss.
• Antiresorptive agents are investigated to mitigate spaceflight-induced bone changes.
• International collaboration between NASA and JAXA on spaceflight bone loss.

Purpose of the Study:

• To evaluate the efficacy of alendronate plus exercise in preventing bone mass and strength decline in astronauts.
• To assess the impact on urinary calcium and bone resorption markers during spaceflight.
• To compare exercise devices for their effectiveness in mitigating bone loss.

Main Methods:

• Seven astronauts received weekly oral alendronate (70 mg) before and during a 5.5-month International Space Station (ISS) mission.
• Exercise included a treadmill, cycle ergometer, and resistance devices (interim and ARED).
• Bone density (DXA, QCT) and bone metabolism biomarkers were measured pre- and post-flight.

Main Results:

• The advanced resistance exercise device (ARED) significantly reduced bone loss compared to older devices.
• Alendronate combined with ARED attenuated declines in bone mineral density (spine, hip, pelvis) and hip bone mass (trabecular, cortical).
• This combination also reduced elevated bone resorption markers and urinary calcium excretion.

Conclusions:

• Combining exercise with bisphosphonates may protect bone health during extended space missions.
• Advanced resistance exercise is more effective than older devices in preserving bone.
• Alendronate and exercise represent a promising strategy for astronaut bone health.