Burke L. M. and J. A. Hawley. (2002). Effects of short-term fat adaptation on metabolism and performance of prolonged exercise. Medicine & Science in Sports & Exercise, 34, 1492-1498.

1. The authors of the article focused on the research of the optimization of nutrition and training process. One of their major goals was to optimize the stores of carbohydrates along with maximization of fat oxidation in the process of physical exercises.
2. The researchers used empirical methods of the study. They observed their subjects in the process of continuous, submaximal (60-70% of maximal O 2 uptake [VO 2max ]) exercises. In such a way, they retrieved empirical data on the effect of exercises on optimization of stores of carbohydrate and maximal fat oxidation.

3. In the result of their research, the authors found out that such “nutritional periodization” encompasses 5-6 d of a high-fat diet (60-70% E) followed by 1-2 d of high-CHO intake (70-80% E; CHO restoration). The experiments have revealed the fact that ingestion of a high-fat diet by endurance-trained athletes results in substantially higher rates of fat oxidation and concomitant muscle glycogen sparing during submaximal exercise compared with an isoenergetic high-CHO diet. Moreover, fat oxidation is higher during the exercises even when CHO availability is increased. To prove these the researchers varied the availability of CHO by giving athletes to consume a high-CHO meal before exercise and ingesting glucose solutions during exercise.


4. Obviously, the article provides important information on the effects of exercises and CHO consumption before and during exercises on the process of fat oxidation. The researchers used experiments to prove their assumptions and findings. On the other hand, experiments conducted by the researchers do not provide clear benefits to the performance of prolonged endurance exercise. This is why it is hardly possible to forecast long-run effects of exercises and further researches in this direction are needed.

5. The results of the study can be applied practically since the results show the way in which it is possible to accelerate fat oxidation. Therefore, the findings of the study can be used in the training process to decrease the amount of fat and increase the muscle growth of athletes.

Stepto L. M. et al.. (2002). Effect of short-term fat adaptation on high-intensity training. Medicine & Science in Sports & Exercise, 34, 449-55.
1. The authors of the study attempted to determine the effect of short-term (3-d) fat adaptation on high-intensity exercise training in seven competitive endurance athletes (maximal O2 uptake 5.0 +/- 0.5 L x min(-1), mean +/-SD). In such a way, they wanted to reveal the interdependence between the intensity of exercises and fat adaptation.
2. In terms of the study, the subjects consumed a standardized diet on d-0 then, in a randomised cross-over design, either 3-d of high-CHO (11 g x kg(-1)d(-1) CHO, 1 g x kg(-1) x d(-1) fat; HICHO) or an isoenergetic high-fat (2.6 g CHO x kg(-1) x d(-1), 4.6 g FAT x kg(-1) x d(-1); HIFAT) diet separated by an 18-d wash out. On the 1st (d-1) and 4th (d-4) day of each treatment, subjects completed a standardized laboratory training session consisting of a 20-min warm-up at 65% of VO2peak (232 +/- 23W) immediately followed by 8 x 5 min work bouts at 86 +/- 2% of VO2peak (323 +/- 32 W) with 60-s recovery.
3. Eventually, researcher revealed the fact that in the process of intensive exersise respiratory exchange ratio (mean for bouts 1, 4, and 8) was similar on d-1 for HIFAT and HICHO (0.91 +/- 0.04 vs 0.92 +/- 0.03) and on d-4 after HICHO (0.92 +/- 0.03) but fell to 0.85 +/- 0.03 (P < 0.05) on d-4 after HIFAT. Accordingly, the rate of fat oxidation increased from 31 +/- 13 on d-1 to 61 +/- 25 micromol x kg(-1) x min(-1) on d-4 after HIFAT (P < 0.05). Blood lactate concentration was similar on d-1 and d-4 of HICHO and on d-1 of HIFAT (3.5 +/- 0.9 and 3.2 +/- 1.0 vs 3.7 +/- 1.2 mM) but declined to 2.4 +/- 0.5 mM on d-4 after HIFAT (P < 0.05). Ratings of perception of effort (legs) were similar on d-1 for HIFAT and HICHO (14.8 +/- 1.5 vs 14.1 +/- 1.4) and on d-4 after HICHO (13.8 +/- 1.8) but increased to 16.0 +/- 1.3 on d-4 after HIFAT (P < 0.05). On the basis of this findings, the researchers arrived to the conclusion that: competitive endurance athletes can perform intense interval training during 3-d exposure to a high-fat diet; such exercise elicited high rates of fat oxidation, but compared with a high-carbohydrate diet, training sessions were associated with increased ratings of perceived exertion.
4. The strength of the study lies in the fact that researches managed to prove the close interrelation between high intensiveness of training and fast fat adaptation. On the other hand, they failed to extrapolate their researchers on a long-term process of fat adaptation. In other words, fat adaptation can be fast in a short-run, during the training, while the researchers fail to find ways to make effective fat adaptation a long-lasting process.
5. Basically, the study can be applied in the training process to accelerate fat adaptation through intensification of training.

References:
Burke L. M. and J. A. Hawley. (2002). Effects of short-term fat adaptation on metabolism and performance of prolonged exercise. Medicine & Science in Sports & Exercise, 34, 1492-1498.
Stepto L. M. et al.. (2002). Effect of short-term fat adaptation on high-intensity training. Medicine & Science in Sports & Exercise, 34, 449-55.

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