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No spontaneous second wind in muscle phosphofructokinase deficiency
Ronald G Haller1, John Vissing
1Neuromuscular Center, Institute for Exercise and Environmental Medicine of Presbyterian Hospital, Dallas, TX 75231, USA. rhaller2@earthlink.net
Neurology
|January 14, 2004
Summary
Patients with McArdle's disease experience a "second wind" during exercise, but those with muscle phosphofructokinase deficiency do not. This suggests that metabolizing blood glucose is crucial for this exercise adaptation.
Area of Science:
- Exercise Physiology
- Metabolic Myopathies
- Biochemistry
Background:
- The spontaneous second wind in McArdle's disease (MD) involves enhanced oxidation of blood-borne fuels, increasing exercise capacity.
- Muscle phosphofructokinase deficiency (PFKD) impairs both muscle glycogen and blood glucose metabolism.
Purpose of the Study:
- To investigate if impaired glucose metabolism in PFKD prevents the development of a spontaneous second wind.
- To compare exercise responses in patients with MD and PFKD.
Main Methods:
- Compared spontaneous second wind development during cycle exercise in 29 MD patients and 5 PFKD patients.
- Monitored heart rate, perceived exertion, oxygen utilization, and blood lactate/ammonia levels.
- Utilized both constant and variable workload protocols.
Main Results:
- All measured variables were similar between MD and PFKD patients early in exercise.
- MD patients exhibited a spontaneous second wind, characterized by improved work and oxidative capacity.
- No PFKD patients demonstrated a spontaneous second wind.
Conclusions:
- Muscle phosphofructokinase deficiency prevents the typical spontaneous second wind observed in McArdle's disease.
- The ability to metabolize blood glucose is essential for achieving a spontaneous second wind during exercise.