Abstract
Background. To assess how muscle ischaemia and isometric fatiguing contraction influence oxygen content in striated muscle. Methods. We simultaneously measured changes in hemoglobin near-infrared (NIR) spectroscopy and in surface EMG before, during, and after muscle ischaemia and ischaemia plus muscle isometric fatiguing contraction. Seventeen health male subjects (age range: 19-40 yrs) were examined in our Clinical Neurophysiology Unit. Test I (9 subjects): hemoglobin NIR spectroscopy and stimulated surface EMG were measured for 2 minutes at rest, for 4 minutes during complete ischaemia of tibialis anterior muscle, and for twelve minutes during recovery. Test II (all subjects): hemoglobin NIR spectroscopy and surface EMG were measured for 2 minutes with the subjects performing brief non-fatiguing contractions, for 4 minutes with the subject performing maximal isometric contraction in complete ischaemia, and for twelve minutes during recovery. EMG parameters measured: median density frequency (MDF); muscle fiber conduction velocity (MFCV). NIR spectroscopy parameters measured: percentage of amplitude decrement (%AD) and nadir time (NT) during ischaemia and ischaemic effort; half-recovery time ( 1/2 RT) from ischaemia effort. Results. At EMG, we observed a significant shift towards lower values of both MFCV and MDF during fatiguing isometric contraction. MDF recovery was faster then MFCV recovery. At NIR spectroscopy, the 1/2 RT slowed a fast pattern in twelve subjects and a slow pattern in five. A significant relationship was found between AD% and 1/2 RT values of test I and AD% and 1/2 values of test II. We found a positive relationship between NT and 1/2 RT in test II. Conclusions. Surface EMG and hemoglobin NIR spectroscopy can be applied simultaneously to evaluate both fatigue intensity and blood flow changes in striated muscle.
Original language | English |
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Pages (from-to) | 83-92 |
Number of pages | 10 |
Journal | Journal of Sports Medicine and Physical Fitness |
Volume | 39 |
Issue number | 2 |
Publication status | Published - Jun 1999 |
Keywords
- Electromyography methods
- Muscle, skeletal blood supply
- Myoelectrical signal
- Spectroscopy, near infrared
ASJC Scopus subject areas
- Public Health, Environmental and Occupational Health
- Physical Therapy, Sports Therapy and Rehabilitation
- Orthopedics and Sports Medicine