PT in Astronaut

PHYSIOTHERAPY IN ASTRONAUT   

INTRODUCTION
 ▪ Astronauts are the unique population of physically and mentally fit individuals who have to travel from gravity to microgravity and back to the gravity.
▪ Microgravity is an environment in which body experiences less or no gravitational force.
 ▪ Astronauts in space undergo similar physiological adaptations as seen in senile bed ridden patient or those seen with detraining in athletes.
 ▪ And these effects of microgravity adversely affects astronaut’s fitness & interfere with space mission activities.
▪ A well planned exercise training program is essential to prevent these adverse effects while in space & to regain fitness post flight.
OBJECTIVE
•To expertise in the rare field of physiotherapy.
•To gain the knowledge about the effects of microgravity in Astronaut in order to plan the best exercise programme.
 •To maintain the health of Astronaut before , during and after flight to safely carry out the space mission.
•To enhance the scope of practice and professional standard.
METHODOLOGY
•Various journals related to exercise training for Astronauts have been viewed carefully.
•Search words were microgravity, astronauts, exercise, rehabilitation and physiotherapy.
•Focus on the adverse effects of microgravity on different systems of Astronaut body.
•Study on the specific exercise modalities in space.
FINDINDS
•PHYSIOLOGICAL ADAPTIONS- Depends on the duration of the flight
1. Short space flight- 1 to 14 days.
2. Long space flight- more than 2 weeks.
 These adaptations occur due to two major factors influenced by microgravity which are:
1.Reduced hydrostatic gradient and
2.Reduced ground reaction force resulting in unloading and hence disuse of weight bearing structures during the space stay.
CARDIOVASCULAR ADAPTATIONS
• Due to the microgravity there is a reduced hydrostatic gradient. Blood and fluid volumes shift upwards and move in thoraco-cephalic region, resulting in puffy face appearance as fluid relocates from extracellular to intracellular space.
• There is reduction in total cardiac work. MRI indicates cardiac atrophy during long as well as short space flight.
• There is a major reduction in orthostatic tension on returning to Earth’s atmosphere and possibility of postural hypotension on return to full gravity.
• Convertino and colleagues have also suggested that there could be increased leg venous compliance because of which veins of legs can hold more blood resulting in decreased end diastolic pressure.
PULMONARY ADAPTATIONS
•Pulmonary diffusing capacity for carbon monoxide increases in the sitting and standing position during 3 days in microgravity.
•And then return to preflight baseline values.
•This results in reduced maximal exercise capacity.
BODY FLUID ADAPTATION
• The plasma volume and RBCs decreases during both, short as well as long space flights.
• Haemoglobin levels remain unchanged/slightly increased after short spaced flight while it decreases after long space flight.
• The red cell morphology does not change after a short space flight but there is a rapid reversal of in flight changes in red blood cell morphology which occur due to increased potassium influx during long space flight.
• Astraunaut’s weight loss upto 5.9 kg due to loss of fluid, fats and proteins  because of inadequate intake.
NEUROSENSORY SYSTEM ADAPTATION
•40-70% of astronauts exhibit inflight neuro-vestibular effects  i.e. postural illusions, sensation of rotation, dizziness, nystagmus, vertigo and space motion sickness like pallor, cold sweating, nausea and vomiting.
•Motion sickness can subside after 2-7 days.
• In 60% of astronauts neurovestibular deficits persist after landing due to morphological changes in otholiths organs when in flight.
69% clumsiness
66% gait disturbance
32% vertigo while walking
29%vertigo while standing
15% nausea
10% difficulty concentrating
 8% vomiting


MUSCULOSKELETAL ADAPTATION
•Microgravity leads to reduced ground reaction force resulting in reduced loading and disuse of weight bearing structures and less muscle activation. This results in muscle atrophy and bone demineralization.
•Bone demineralization results in altered calcium metabolism.
• Bone mineral loss accounts for about 4 % in the weight bearing bones, the magnitude of which is dependent on the length of the exposure to the flight.
ROLE OF EXERCISE 
•PRE FLIGHT PHASE• Regular aerobic exercise in the pre flight period keep their cardio vascular performance and endurance to the best of their abilities with the use of treadmill, cycle ergometer, Exercises under water, Horizontal walking.
• The five basic strategies that stimulate microgravity environment are :
• 1. head-down rest on bed with head down tilt of 3 to 12 degrees
• 2. water immersion wherein astronauts lie supine in water tank for up to 24 hours performing complex hand to eye coordination task to mimic the skills required in space flight
• 3. wheel chair confinement  like paraplegics which produces postural hypotension
• 4. immobilization and bed confinement similar to a bed ridden patient
• 5. short parabolic flights to achieve brief period of weightlessness.

•IN FLIGHT PHASE— • Exercises to maintaining the range of motion at all the joints including spine & maintaining the strength of hip, shoulder & back muscles.
 • Exercise modes like treadmill, cycle ergometer, leg rowing ergometer and upper and lower body multijoint dynamic resistance exerciser prove effective for inflight workouts.
• Lifting of weights for strength training during space flight does not have any role because everything is practically weightless in microgravity.
• Interim resistance exercise device or IRED has two cylinders, inside each cylinder there are 13 disks joined together by series of rubber connections. Astronauts can change the resistance by changing the setting for the number of the disks to use.

• Space Cycle leads to reversal of cephalic fluid shift, thus minimizing post flight orthostatic intolerance; Pedaling maintains muscular and cardiovascular fitness and enhances skeletal homeostasis.
 •Lower-body negative pressure device assesses the orthostatic intolerance during the flight and post flight. It applies negative pressure on the lower limb and sequesters blood from the thorax into dependent regions of the pelvis and legs, effectively decreasing central blood volume.
• Self-powered human centrifuge device creates a short arm centrifuge with a head-to-toe acceleration orientation

•POST FLIGHT PHASE— • Post landing, the recovery occurs at variable pace during the post flight phases.
•Phase 0-- Landing to 1st day post landing. Orthostatic intolerance and vestibular dysfunction need to be treated in this phase.
•Phase 1-- Up to three days from return. Issues of physiologic readaptation , rest, psychological support, readjustment of circadian rhythm, injury prevention and diet & nutrition. Physical activities include progression from stretching, active exercises, massage and assisted walking as tolerated.
•Phase 2-- extends 7 to 14 days from return. Rehabilitation during this phase focuses mainly on the physical conditioning. Stretching, exercise and massage are continued.
•Phase 3– Up to 45 days and exercise includes •Aerobic •Anaerobic •Proprioceptive training •Agility training •Use of vibration platform to stimulate bone formation.
CONCLUSION
•Optimal exercise training is required to minimize the spaceflight’s  harmful deconditioning effects on the astronauts physiological function, performance and overall health due to microgravity. •Thus exercise training is one of the essential component for the rehabilitation of astronauts.

REFERENCE--https://www.researchgate.net/publication/269740816 Exercise Training for Astronauts - A Review Article · January 2013 DOI: 10.5958/j.0973-5674.7.4.123 Hiral S Master University of Delawar Swati Surkar East Carolina University