What’s Sunita Williams doing in gravity rehab? Neurologist details body reconditioning exercises that get every space traveller back on their feet

How to counter muscle atrophy and bone loss

On Earth, muscles constantly work against gravity, whether we are standing, walking, or simply maintaining posture. In space, the lack of gravitational resistance leads to muscle atrophy, particularly in the legs, back, and core. That’s why astronauts need endurance and motor control upon return. In space, bone density decreases at a rate of 1-2% per month, making astronauts vulnerable to fractures upon their return.

• Progressive weight-bearing exercises: Treadmill walking, running, and resistance training are key to rebuilding muscle mass and strength.
• Calcium and vitamin D supplementation: These are essential for bone mineralization and recovery.
• Hydrotherapy (water-based exercises): This helps reintroduce gravitational load without excessive strain on weakened muscles and bones.

How to manage cardiovascular changes

On Earth, gravity pulls blood toward the lower body, but in space, fluids shift upward, causing astronauts to have puffy faces and thinner legs. This redistribution confuses the body’s regulatory systems, leading to a reduced production of blood volume, which can cause astronauts to faint and feel dizzy upon returning to Earth.

Additionally, without gravity, the heart doesn’t have to work as hard to pump blood against resistance, leading to slight cardiac atrophy.

Cardiovascular reconditioning: Light cycling, rowing, and swimming gradually rebuild heart strength.
Tilt-table training: Lying on a tilted surface to help the body re-adapt to proper blood flow regulation.
Compression garments: These help prevent blood pooling in the lower body, reducing dizziness.

Brain Function Adaptation

Without a constant sense of “up” and “down,” astronauts often experience space motion sickness, disorientation, and nausea in the first few days. Upon return to Earth, astronauts struggle with imbalance, dizziness, and delayed reaction times.

Balance training: Walking on unstable surfaces, using stability balls, and practising eye-tracking exercises help retrain spatial awareness.

Neuromuscular therapy: Activities that challenge coordination and motor control (such as tai chi or virtual reality simulations) accelerate the brain’s adaptation back to Earth’s environment.

Gut health imbalance

Gravity plays a significant role in digestion by helping food move downward through the esophagus, stomach, and intestines. In space, food moves more slowly. Space travel alters the gut microbiome, reducing beneficial bacteria. This is compounded by dehydration, which is common in space due to fluid shifts.

High-fibre diet: Supports gut motility and regular bowel movements.
Probiotic supplementation: Restores beneficial gut bacteria.
Hydration therapy: Drinking electrolyte-balanced fluids helps prevent constipation and nutrient malabsorption.

Vision changes

A lesser-known effect of microgravity is Spaceflight-Associated Neuro-Ocular Syndrome (SANS), when fluid shifts cause increased pressure on the optic nerve, leading to blurry vision and difficulty focussing. This occurs due to flattening of the eyeball and swelling of the optic disc. Eye exercises are needed to restore focus and depth perception while controlled salt and fluid intake reduce intracranial pressure.

So even if you are not an astronaut but an orbital traveller, a protocol is available to get you back on your feet.