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Changes in jejunal myoelectrical activity during exercise in fed untrained dogs
M J Kenney1, A Flatt, R W Summers
1Department of Exercise Science, University of Iowa, Iowa City 52242.
The American Journal of Physiology
|May 1, 1988
Summary
Exercise alters canine jejunal myoelectrical activity, with slow-wave frequency increasing during prolonged activity and recovery. Myoelectrical patterns, not just spike-burst frequency, are key to understanding exercise-induced gastrointestinal issues.
Area of Science:
- Gastroenterology
- Exercise Physiology
- Canine Physiology
Background:
- Exercise can trigger gastrointestinal symptoms.
- Understanding the impact of physical activity on the small intestine is crucial for athletes and clinicians.
Purpose of the Study:
- To investigate the effects of varying exercise intensities and durations on jejunal myoelectrical activity in dogs.
- To determine if changes in slow-wave frequency or spike-burst activity correlate with exercise-induced gastrointestinal alterations.
Main Methods:
- Seven female dogs (15-20 kg) were surgically implanted with electrodes on the proximal jejunum.
- Dogs underwent treadmill exercise at different intensities (50-70% heart rate reserve) and durations (30-90 min).
- Jejunal myoelectrical activity, core temperature, and heart rate reserve were monitored.
Main Results:
- Slow-wave frequency increased significantly during prolonged exercise (90 min) and short-term recovery (30 min) at 70% HRR, correlating with increased core temperature.
- Spike-burst frequency showed a small increase with moderate exercise (50% HRR) but decreased significantly with extended exercise and during recovery.
- Exercise induced migrating myoelectrical complexes or "clustered contractions" in the jejunum.
Conclusions:
- Exercise significantly alters jejunal myoelectrical activity in dogs.
- Changes in jejunal myoelectrical patterns, rather than solely spike-burst frequency or duration, are likely more significant in explaining exercise-induced gastrointestinal symptoms.