PRINCIPAL INVESTIGATOR ( S ) : Eduard C. Burchard , and Arnauld E. Nicogossian 



EXPERIMENT TITLE/NUMBER : Achilles Tendon Reflex 



PROGRAM/MISSION : Apollo-Soyuz Test Project 



CLASSIFICATION : Human 



DISCIPLINE(S) : Musculoskeletal, Neurosensory 



OBJECTIVES : To measure the Achilles tendon reflex in order to detect changes 

 in neuromuscular function. 



PROTOCOL : The measurement was performed during the physical examination on 

 all three astronauts on days F-30, F-15, and on R+0. A photoelectric cell was 

 employed to time the Achilles tendon reflex by measuring the displacement of 

 the foot. A tap on the Achilles tendon with a percussion hammer caused the 

 foot to move in the light beam and generate a change in photocell voltage. 

 The changes were recorded on electrocardiograph paper to give a time-position 

 plot of reflex action. Measurements were made from the beginning of the 

 hammer tap to one-half the relaxation period. 



EQUIPMENT : Photomotograph . 



RESULTS : The ACDR and the DMP exhibited a shortening in the reflex duration 

 time, whereas the CMP showed an increased reflex time. In addition, all 

 crewmembers showed significant fine tremor, as documented by tracings which 

 could reflect the effects of the inhaled vapor of nitrogen tetroxide. This 

 tremor which was recorded on the baseline tracings of the Achilles tendon 

 reflex was also clinically observed in the fingers for a short time on R+0. 



CONCLUSIONS : The data show the predicted postflight change in the Achilles 

 tendon reflex time. For the first time since the tendon reflex measurement 

 was introduced, postflight tremor was documented. 



PUBLICATIONS: 127 



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