Original articles  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2002 December;42(3):438-45

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Effect of linear polarized near-infrared light irradiation on flexibility of shoulder and ankle joints

Demura S. ¹, Yamaji S. ², Ikemoto Y. ³

¹ Department of Physical Education Kanazawa University, Kanazawa, Japan 2 Fukui National College of Technology, Fukui, Japan 3 Yonago National College of Technology, Yonago, Japan

Back­ground. ­There is a pos­sibility ­that ­heat stim­ulus by ­linear polar­ized ­near-­infrared ­light irra­di­a­tion (PL: ­Super ­Lizer HA-30, ­Tokyo Med­ical Labor­a­tory) ­improves the ­range of ­joint ­motion, ­because the flex­ibility of ­soft-­part tis­sues, ­such as a ­muscle or a ­tendon, is ­improved by ­increasing the ­muscle tem­per­a­ture. The pur­pose of ­this ­study was to ­examine the influ­ence of PL-irra­di­a­tion on the ­ranges of ­shoulder and ­ankle ­motions.
­Methods. Experi­mental ­design: 30 ­healthy ­young ­adults (15 ­males: ­mean±SD, age 19.1±0.8 yrs, ­height 173.3±4.6 cm, ­body ­mass 68.5±8.0 kg and 15 ­females: ­mean±SD, age 19.2±0.7 yrs, ­height 162.3±4.5 cm, ­body ­mass 58.1±6.6 kg) par­tic­i­pated in the experi­ment ­under PL-irra­di­a­tion and no-irra­di­a­tion (pla­cebo) con­di­tions. Meas­ures: the ­angles of ­shoulder and ­ankle ­joint ­motions ­were meas­ured ­twice, ­before and ­after the PL- and pla­cebo-irra­di­a­tions. The ­angle of a ­motion was ­defined as the ­angle con­necting 3 ­points at lin­e­arity as fol­lows: for the ­shoulder, the ­greater tro­chanter, acro­mion, and ­caput ­ulnare, and for the ­ankle, the ­knee ­joint, ­fassa of lat­eral mal­le­olus and met­a­carpal ­bone. ­Each ­angle was meas­ured ­when a sub­ject ­extended or ­flexed max­i­mally ­without sup­port.
­Results. The ­trial-to-­trial reli­ability of ­each ­range of ­joint ­motion was ­very ­high. All param­e­ters in PL-irra­di­a­tion ­were sig­nif­i­cantly ­larger in post­ir­ra­di­a­tion ­than pre-irra­di­a­tion, and the ­value of post­ir­ra­di­a­tion in PL-irra­di­a­tion was sig­nif­i­cantly ­greater ­than ­that for pla­cebo. The ­ranges of ­shoulder and ­ankle ­motions in pla­cebo-irra­di­a­tion ­were ­also sig­nif­i­cantly ­greater in post­ir­ra­di­a­tion ­than pre-irra­di­a­tion. More­over, the ­change ­rate for ­each ­range of ­joint ­motion ­between pre- and post­ir­ra­di­a­tions was sig­nif­i­cantly ­greater in PL-irra­di­a­tion in ­both ­joints. In PL-irra­di­a­tion, ­most ­subject’s ­motions ­were ­greater in post­ir­ra­di­a­tion ­than pre-irra­di­a­tion, but not in the pla­cebo-irra­di­a­tion. The ­effect of PL-irra­di­a­tion ­tended to be ­greater on sub­jects ­with a ­small ­range of a ­joint ­motion.
Con­clu­sions. It is con­sid­ered ­from the ­present ­results ­that the ­ranges of ­shoulder and ­ankle ­motions ­became ­greater ­with PL-irra­di­a­tion, and is effec­tive as a ­warming-up ­method.