Affiliations: [a] Department of Biosurgery and Surgical Technology,
Division of Surgery, Oncology, Reproductive Biology and Anaesthetics (SORA),
Faculty of Medicine, Imperial College London, Charing Cross Hospital, London,
UK
Note: [] Address for correspondence: Dr. Paul H. Strutton, The Nick Davey
Laboratory, Biosurgery and Surgical Technology, Division of Surgery, Oncology,
Reproductive biology and Anaesthetics (SORA), Faculty of Medicine, Imperial
College London, Room 7L15, Charing Cross Hospital, London W6 8RF, IK. Tel.: +44
(0)20 8383 8837; Fax: +44 (0)20 8383 8835; E-mail: [email protected]
Abstract: Muscle fatigue has high relevance in human performance and may
contribute to the high incidence of back pain amongst athletes. However, the
term fatigue is often poorly defined and is used inconsistently, frequently
being interchanged with endurance. This study aimed to establish whether the
Biering-Sorensen test and a test of fatigue for the abdominal muscles were
effective at inducing fatigue using a well established definition. Twenty
medical students were subjected to two protocols (A & B). Using a Cybex
norm isokinetic dynamometer, the isometric peak torques during extension and
flexion were measured before and after each protocol. Protocol A involved a 45
second maximal isometric contraction within the dynamometer while Protocol B
entailed a Biering-Sorensen (submaximal) test for extension and a sit up crunch
for flexion. Extension testing followed flexion testing. Significant reduction
in peak mean torque occurred only in flexion for both protocols. The
Biering-Sorensen test did not result in a decrease in peak torque suggesting
minimal fatigue (using the definition used in this study). A weak correlation
was found between the length of time the Biering-Sorensen test was held and the
fatigue index. The Biering-Sorensen test does not appear to reduce maximum
voluntary contraction strength and remains a test of endurance. However, a
similar test for the abdominal muscles did induce fatigue. Further research is
required to develop an effective protocol to assess trunk extensor fatigue.
Keywords: Dynamometry, isokinetic, isometric, fatigue, endurance, back pain
