Abstract
Metabolic costs of force generation were compared for constant-frequency and catchlike-inducing electrical stimulation. Repetitive catchlike-inducing trains consisted of 2 interpulse intervals (IPIs) at 12.5 ms, 1 IPI at 25 ms, and 5 IPIs at 50 ms. Constant-frequency trains consisted of 8 IPIs at 37.5 ms. One train was delivered to the peroneal nerve every 2.5 s for 36 times under ischemic conditions. Anaerobic adenosine triphosphate (ATP) turnover was determined using 31-phosphorus magnetic resonance spectroscopy (P-MRS) of the human tibialis anterior muscle. Compared with constant-frequency trains, catchlike-inducing trains produced a faster force generation and were more effective in maintaining the force-time integral as well as peak force. However, ATP costs of force generation were similar for the catchlike-inducing and constant-frequency stimulation (6.7 +/- 1.1 and 6.6 +/- 1.0 mumol ATP/kg wet weight/N(.)s, respectively, P = 0.601). This suggests that the positive effects of catchlike-inducing stimulation on force maintenance are mediated by potentiated Ca2+ release from the sarcoplasmic reticulum rather than by lower metabolic costs of muscle force generation. Our findings also suggest that catchlike-inducing stimulation produces larger forces in fatigued muscle than constant-frequency trains and thus may be beneficial for muscle training or rehabilitation when muscle loading needs to be maintained in repetitive contractions. (C) 2002 Wiley Periodicals, Inc.
Original language | English |
---|---|
Pages (from-to) | 419-426 |
Number of pages | 7 |
Journal | Muscle & nerve |
Volume | 25 |
Issue number | 3 |
DOIs | |
Publication status | Published - Mar 2002 |
Keywords
- electrical stimulation
- energy metabolism
- muscle contraction
- muscle fatigue
- nuclear magnetic resonance
- HUMAN SKELETAL-MUSCLE
- SINGLE MOTOR UNITS
- HUMAN CALF
- FATIGUE
- CONTRACTIONS
- RECOVERY
- EXERCISE
- ACTIVATION
- PATTERN
- FIBERS