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Effect of oral sucrose shortly before exercise on work capacity in McArdle disease
Susanne Tvede Andersen1, Ronald G Haller, John Vissing
1Neuromuscular Research Unit, Department of Neurology, and Copenhagen Muscle Research Center, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark.
Background:
Oral sucrose (75 g) ingested 40 minutes before exercise improves exercise tolerance in McArdle disease.
Objective:
To determine whether a lower dose of sucrose administered closer in time to exercise could have a similar beneficial effect on exercise capacity in patients with McArdle disease.
Design:
Placebo-controlled crossover.
Setting:
Neuromuscular Research Unit at the Department of Neurology, Rigshospitalet, Copenhagen, Denmark.
Patients:
Six patients with biochemically and genetically diagnosed McArdle disease.
Interventions:
On separate days, the patients were tested after ingestion of either 75 g of sucrose or a placebo 40 minutes before exercise, or 37 g of sucrose or a placebo 5 minutes before exercise. Patients were blinded to test substances.
Main Outcome Measures:
Treatment effectiveness was assessed by monitoring heart rate and perceived exertion during exercise.
Results:
Both sucrose treatments dramatically improved exercise tolerance, compared with the placebo. The low-dose, 5-minute sucrose trial had a more sustained effect on exercise capacity than the 40-minute trial. The more sustained effect was probably related to more continuous glucose uptake from the intestine and correspondingly higher circulating glucose levels later during exercise.
Conclusions:
This study shows that 37 g of sucrose ingested shortly before exercise has a marked and prolonged effect on exercise tolerance in patients with McArdle disease. This treatment is more convenient for the patients and saves more calories than the currently recommended sucrose treatment.
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