Migratory birds are undoubtedly endurance athletes. In fact, their flights last hours to days. Could you imagine? But, unlike mammals that fuel endurance exercise by burning carbohydrates, birds fuel their endurance flights with fat.
In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers were curious about whether the TYPE of dietary fat used to fuel endurance exercise was important. To examine this question, they gave yellow-rumped warblers, Setophaga coronate coronate (pictured above), diets that were high in either n-3 or n-6 long-chain polyunsaturated fatty acids (PUFA) in comparison to a diet low in long-chain PUFAs for 6 weeks. By placing the birds in a wind tunnel for 6 hours, they were able to mimic migratory flight.
Other studies have shown n-3 and n-6 PUFAs can impact exercise performance when examining the whole animal. The current study also focused on how these diets impact skeletal muscle, specifically. While they found that the diets alone altered the fatty acid composition of cell membranes and the activity of metabolic enzymes in muscle, there was no impact of flight on these measurements. These findings show that although PUFAs can impact muscle metabolism, they do not change performance during a 6-hour wind tunnel flight in warblers.
Dick MF, Guglielmo CG. Dietary polyunsaturated fatty acids influence flight muscle oxidative capacity but not endurance flight performance in a migratory songbird. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 316(4): 362-375, 2019.