Abstract
Background: Among n-3 polyunsaturated fatty acids (PUFAs), the most important is α-linolenic acid (ALA). The biological activity of ALA is not equivalent to that of the long-chain n-3 PUFAs, and it has pleiotropic effects, such as functioning as an energy substrate during long-term training when carbohydrate reserves are depleted. The purpose of this investigation was to study the link between the essential dietary and plasma ALA and aerobic performance, which is estimated via maximal fat oxidation (MFO), among skiers. Methods: Twenty-four highly trained male athletes from the Russian cross-country skiing team participated in the study. ALA intake was determined by an original program used to assess the actual amount and frequency of fat consumption. The plasma level of ALA was determined using gas-liquid chromatography. The skiers’ aerobic performance was estimated via MFO and determined by indirect calorimetry using the system “Oxycon Pro”. Results: The consumption of ALA in the diet in half of the skiers was below the recommended level at 0.5 ± 0.2 g/day. The deficiency of plasma ALA levels was on average 0.2 ± 0.1 Mol% for almost all participants. The consumption of ALA in the diet and its level in plasma were associated with MFO (rs = 0.507, p = 0.011; rs = 0.460, p = 0.023). Levels of ALA in plasma (p = 0.0523) and the consumption of ALA in the diet (p = 0.0039) were associated with high aerobic performance. Conclusions: ALA in the diet of the athletes may be used as nutritional support to increase MFO and aerobic performance.
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Key Points
Assessments of the functional state of highly trained athletes take into account the rate of oxidation of energy substrates, i.e., carbohydrates and fats. The role of nutritional factors in improving maximal fat oxidation (MFO) and endurance of athletes in the preparatory and competitive periods and during rehabilitation after intense exercise is poorly understood. n-3 PUFAs are necessary for the energy supply for muscle activity and contribute to maximal oxygen uptake (VO2max) and performance improvement in cyclical sports athletes. ALA can function as an energy substrate during long term training when carbohydrate reserves are depleted. The purpose of this investigation was to study the link between the essential dietary and plasma ALA levels and the aerobic performance of skiers estimated via MFO. The adequate consumption of ALA in the diet is associated with a higher value of MFO. The consumption of ALA in the diet increases the activity of carnitine palmitoyl transferase I and FA translocase (a key protein transporter of FAs), which in turn increases MFO in the mitochondria. ALA can function as an energy substrate during long-term training when carbohydrate reserves are depleted. The lipid composition of skeletal muscle is sensitive to changes in the diet especially when ALA or its conversion products EPA and DHA are potent activators of transcription factors, which are receptors activated by peroxisomal proliferators (PPARs) that regulate genes responsible for fat metabolism. The data suggest that n-3 PUFAs (ALA and its transformation products EPA and DHA) can promote fat oxidation through PPAR dependent and PPAR-independent mechanisms. In this study, evidence shows that essential ALA in the diet plays an important role in increasing MFO and aerobic performance in skiers. Thus, this study indicates that the level of ALA should be increased in the diets of athletes because of the associated increase in the aerobic potential of the body via the use of essential FAs.