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Fatigue in the Superficial and Deep Digital Flexor Muscles During Exercise in T horoughbred Horses
Author(s) -
Takahashi T,
Ohmura H,
Mukai K,
Matsui A,
Aida H
Publication year - 2014
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12267_90
Subject(s) - medicine , isometric exercise , stride , treadmill , flexor muscles , electromyography , hoof , muscle fatigue , physical medicine and rehabilitation , cardiology , physical therapy , anatomy
One of the causes of injury to the superficial digital flexor tendon ( SDFT ) is assumed to be repeated high intensity loading of the tendon. Earlier fatigue of the deep digital flexor muscle ( DDFM ) in comparison to the time of fatigue of the superficial digital flexor muscle ( SDFM ) is also assumed to increase load on the SDFT during long distance running. This study evaluated the fatigue of SDFM and DDFM with maximal exercise. Methods Two wire electrodes were inserted into the SDFM and DDFM of 6 T horoughbred horses (461–557 kg). Electromyogram ( EMG ) and hoof strain gauge signals were recorded at 2,500 H z with horses on an inclined treadmill (6%), and filter processing was applied (high‐pass 10 H z for EMG and low‐pass 200 H z for strain gauge). Integrated EMG (i EMG ), the median frequency ( MF ) of EMG , and the stride frequency ( SF ) were compared using paired t‐test during 100–105% heart rate max exercise and trotting before and after maximal exercise. Results The SF significantly decreased and i EMG of SDFM tended to decrease during maximal exercise (P = 0.055), while MF of EMG in SDFM and DDFM did not change. The i EMG of SDFM and DDFM significantly decreased and MF of EMG in DDFM tended to decrease at a trot after maximal exercise (P = 0.063). Conclusions The DDFM may fatigue earlier than SDFM during long distance running. Further study is needed to evaluate the relationship between the decrease in i EMG of SDFM and DDFM during maximal exercise and the injury to SDFT . Ethical Animal Research The study was approved by the Animal Welfare and Ethics Committee of the J apan Racing Association Equine Research Institute. Sources of funding: J apan Racing Association. Competing interests: none.