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The impact response of the seated subject
Author(s) -
Broman Holger,
Pope Malcolm H.,
Benda Michal,
Svensson Magnus,
Ottosson Charlotte,
Hansson Tommy
Publication year - 1991
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.1100090118
Subject(s) - attenuation , transmissibility (structural dynamics) , spinous process , amplitude , pendulum , mechanics , frequency response , physics , acoustics , materials science , control theory (sociology) , vibration , computer science , optics , engineering , anatomy , vibration isolation , medicine , electrical engineering , quantum mechanics , control (management) , artificial intelligence
An impact method for establishing the dynamic response of the seated subject is introduced. The method employs a pendulum to apply the impact to the suspended seat. Pins are placed in the spinous process at L3. Highly reproducible results are obtained. The results were not affected by the amplitude of impact, implying a linear system. A marked peak of transmissibility is found in the 4–5 Hz range and an attenuation peak is found close to 8 Hz. Both muscle contraction and postural changes affect the dynamic response. A relaxed posture shows greater gain and attenuation peaks. A valsalva stiffens the system and reduces the effective damping. The vertical response of the body probably shows in the 5–6 Hz peak, while the rotational response is probably encompassed in the 8 Hz attenuation peak.