Astronauts may need to jump for better knee health in space

Many researchers worry about the toll that long trips in space may take on the human body. These concerns revolve around the muscle and bone changes that occur in low-gravity environments.

Recent findings indicate that cartilage may also suffer in space, prompting the search for new ways to keep astronauts healthy.

A study led by Marco Chiaberge from Johns Hopkins University suggests that jump-based workouts might be key to protecting astronaut’s knees.

The researchers placed groups of mice on different activity regimens. The jump-trained mice displayed a 26% boost in cartilage thickness and a 110% advantage over restricted-mobility mice, as well as a 15% gain in bone mineral density.

Jumping to protect astronauts’ knees

The experts used a specialized setup to see how bounding movements might protect knee tissue. Early signs showed that mice could handle these sessions and develop healthier joint structures.

Routines involving repetitive jumping, often called plyometric training, are known for building muscle power. This type of training now appears to offer a dual benefit by preserving tissue that cushions the ends of bones.

The jump movements place short, high-impact forces on the joints. The load appears to stimulate cells in the knees to maintain or even enhance articular cartilage – the protective layer covering the bones.

Articular cartilage does not have a rich blood supply, so it relies on mechanical forces to bring nutrients in. Jumping might be one of the more efficient ways to spark that process.

Soft tissues are vulnerable to damage

Cartilage cushions the joints so bones don’t grind against each other. This cushion is particularly important in weight-bearing joints like knees and hips.

Osteoarthritis is a common joint disorder that happens when cartilage wears away. Because this tissue regenerates slowly, people often face chronic pain and limited range of motion once it breaks down.

Low-gravity conditions speed up physical decline, which is a concern for crew members on extended missions. Microgravity, or near-weightlessness, weakens muscles and bones, making the body’s soft tissues more vulnerable to damage.

Exercising in space is already mandatory, with astronauts often devoting hours each day to keep their bodies functional. The new study hints that shorter, more intense jump routines could help astronauts avoid knee trouble.

A simple exercise for astronauts

Astronauts experience muscle atrophy and bone loss in orbit. Joint issues had received less attention – until studies revealed possible cartilage thinning in people who stayed in microgravity for several months.

“Think about sending somebody on a trip to Mars, they get there and they can’t walk because they developed osteoarthritis of the knees or the hips and their joints don’t function,” said Chiaberge. He believes jump-centered training is a practical solution.

Space agencies explore various countermeasures, including resistance bands and treadmill harnesses. Certain platforms can simulate gravity, but they are bulky and not always suited for daily routines.

Jump-based exercises use minimal equipment, which could save precious cargo space on long-duration missions.

Furthermore, limited living quarters make workouts challenging in orbit. A compact system for plyometric sessions might address these constraints without requiring heavy gear.

“Leg strength is particularly important and most highly impacted by microgravity, so any procedures that can address multiple aspects of muscle deconditioning, and maybe even reduce the two-hour daily exercise requirement in space, would be most welcome,” said Mark Shelhamer, a professor at the Johns Hopkins School of Medicine.

Looking beyond space

People may suffer from cartilage deterioration if they are bedridden or recovering from accidents. Some hospitals even perform bed-rest studies to mimic the muscle and bone loss seen in space travelers.

Adaptations from space research have helped develop rehab programs for those with limited mobility.

Individuals with mild joint discomfort often rely on low-impact exercises to avoid aggravating pain. If a carefully supervised jump routine can safely build strength, it may offer new hope for active aging.

This concept extends to sports medicine too. Trainers might explore short, targeted jump sessions to help athletes maintain joint resilience during off-season breaks.

Future research directions

“Now that we got our first clue that one type of exercise can increase cartilage, which was completely unknown before, we could start looking into other types of cartilage,” said Chen-Ming Fan, a musculoskeletal biologist at Carnegie Science.

He is eager to see if different tissues could show similar improvements from the same training.

Fan’s team wants to establish the ideal frequency for jump sessions to benefit astronauts. Overdoing it could be risky for injured knees, but too little may not yield the desired effect.

Studies with humans will likely be the next phase. Controlled clinical trials might confirm whether short bursts of jumping protect the knees against degenerative changes.

The possible applications range from elite sports to everyday fitness routines. Targeted jump workouts could help healthy individuals maintain strong joints well into old age.

The study is published in npj Microgravity.

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