During periods of prolonged exercise, skeletal muscle relies on fatty acid oxidation for energy as muscle glycogen stores are depleted. Altered energy production due to very-long chain acyl-coA dehydrogenase deficiency (VLCAD) can lead to muscle symptoms including cramps, pain, and rhabdomyolysis. "Exercise precautions" to prevent metabolic decompensation and rhabdomyolysis have been a routine part of practice. Yet, there is evidence that in individuals with long-chain fatty acid oxidation disorders (LC-FAOD), routine physical activity promotes lean body mass (LBM) and reduces heart rate during activity. Thus, promoting regular exercise and providing sufficient energy and fluids to support activity can contribute to positives outcomes.
Consumption of medium chain triglycerides (MCT) prior to exercise has been shown to improve exercise tolerance by providing an available substrate for fatty acid oxidation in muscle. Use of carbohydrates before and during exercise has been reported; however, evidence indicates that MCT, with or without carbohydrate, is the preferred pre-exercise intervention. Carbohydrate intake is indicated during prolonged exercise and, along with protein, for refueling after exercise. Extra fluids are needed before, during, and after exercise to maintain hydration.
Asymptomatic individuals with mild/moderate VLCAD do not need to overly restrict physical activity and national guidelines regarding regular physical activity can inform exercise advice. Those with severe and/or symptomatic VLCAD may need to adjust the duration and intensity of physical activity to prevent or reduce symptoms. Nutrition interventions to support regular physical activity for age include providing adequate energy intake adjusted to activity level and scheduled to coincide with planned exercise. Pre-exercise MCT and snacks during and after exercise should be incorporated into the nutrition prescription.
Encourage individuals with VLCAD to participate in normal physical activity for age, as tolerated, with appropriate energy support. Limitations of exercise duration and intensity may be needed in some individuals.
Insufficient Evidence | Consensus | Weak | Fair | Strong |
Conditional | Imperative |
Provide MCT as an energy source 20 minutes prior to exercise, and adjust dose (range 0.1-0.3 g/kg total body weight or 0.25-0.5 g/kg based on LBM) to improve exercise tolerance for those not tolerating physical activity.
Insufficient Evidence | Consensus | Weak | Fair | Strong |
Conditional | Imperative |
Counsel individuals with VLCAD regarding appropriate fluid needs for physical activity.
Insufficient Evidence | Consensus | Weak | Fair | Strong |
Conditional | Imperative |