Endurance Training on Muscle Fat

¶ … Endurance Training on Muscle Fat Metabolism During Prolonged Exercise

In this paper, the effects of endurance training will be discussed with special reference to their impact on the muscle fat metabolism while prolonged exercises. The paper will talk about the overall increase and decrease in the levels of different acids in the body as well as the overall bodily fluids within the body and how they then impact the overall mobility of the muscles. The paper will also give special attention to the importance of exercise for athletes and how the use of endurance exercise impacts their muscle metabolism. We will further discuss the differences in the fat metabolism between men who are endurance trained and those who are not. Furthermore we will also be discussing: 1) Influence of repeated sprint training on pulmonary O2 uptake and muscle deoxygenation kinetics in humans; 2) Influence of endurance training on muscle kinetics during high-intensity exercise; 3) the possible increased physical activity decreasing the hepatic free fatty acid uptake; and 4) Effects of diet on muscle triglyceride and endurance performance. All of the 4 aspects mentioned above will be discussed from an analytical point-of-view. The paper will thus be divided into four separate sections: 1) abstract; 2) introduction -- a brief definition of topic and its background will be given; 3) the literature review -- this will be the main part of the paper, analysis the topic will be given here with references to prior similar researches; and 4) conclusion -- this section will give a summary of the topic and the paper.

Introduction

Exercise is one of the most important aspects of any individual's life. It is believed that a person not only reduces the overall fat in one's body through exercise but also manages to avoid certain health hazards like blood pressure, heart problems or anxiety in the long run (McArdle et al., 1996a and 1996b). In this paper we will be discussing the aspect of decreasing the free fatty acid (FFA) metabolism through exercise specifically. The fact of the matter is that there are no clear conclusions made yet on the overall effect that exercise has on FFA and oxidation levels in humans. This study will aim to hence make certain deductions that will help formulate a stance on how the endurance training exercises really impact the muscle fat metabolism. We will be discussing numerous researches and analyzing their results to form conclusions (see, Loat and Rhodes, 1993).

Literature Review

In a recent study, Hannukainen and colleagues (2007) studied the heredity-autonomous impact on the FFA uptake in skeletal muscle, the myocardium, and liver through the use of exercise and fitness routines. They utilized the positron emission tomography (PET) in nine different and healthy young men monozygotic twin with inharmonious exercise drills. The results showed that the men who had more consistent and vigorous exercise patterns had similar body mass ratios but lowered fat levels especially in comparison to those who had varying levels of exercise or didn't exercise as much (Hannukainen et al. 2007).

The study also showed that exercises did not have to necessarily be high-endurance to decrease the overall FFA levels in individuals. For example, the study showed that the low-intensity exercise of simple knee-extension also decreased overall FFA levels and increased skeletal muscle and oxygen intake. Other stats in the study included lowered hepatic FFA uptake for the more exercise-prone males then the less exercise-prone males when they were at rest. Numerically the division was as such:

5.5 ± 4.3 for the more exercise-prone males

9.0 ± 6.1 ?mol for the less exercise-prone males (Hannukainen et al. 2007)

These levels stand true for athletes as well. Hence, if we studied this particular research in order to form a definite solution, it would be this: if the overall genetic structure was taken out of the picture, then the overall increase in exercise even at lower-intensity levels had a significant impact on the FFA levels of the normal health levels of male athletes. Furthermore the overall muscle metabolism and skeletal muscle structure also improved significantly as the exercise intensities increase for athletes which show that the muscle metabolism and the FFA levels correspond to exercise in a positive and simultaneous manner (Hannukainen et al. 2007).

In another study, Bailey and colleagues (2009) analyzed the kind of warn-down exercise or follow-up exercise that would be most useful after an endurance-exercise routine in to not only decrease the FFA levels down to a healthy ratio but also increase the overall oxidation levels in healthy individuals. They asserted that the most common pattern was the utilization of low-intensity exercises after an endurance-exercise routine. However, the concluded that the use of repeated all-out sprint training (RST) is a much more useful follow-up exercise then the low-intensity endurance training (ET) routines of an athlete is looking to increase in the oxygen uptake (O2) and muscle deoxygenation (Bailey et al., 2009).

The study sample consisted of a total of 24 individuals: 15 of which were men, between the ages of 8 and 21 with height variations between 12 and 173 cm with body mass body variations between 11 and 71 kg. These were divided in to three groups: one group completed six repeated routines of customized RST routines; the second group completed six repeated routines of customized low-intensity exercises; and, the third group was the control group. The results showed that the overall capacity for muscle fat metabolism decrease was somewhat similar for both routines (RST and low-intensity exercises) but in terms of improved fractional muscle O2 uptake, increase in speed of the O2 kinetics, and an augmented adaptation and tolerance for the high-intensity endurance exercise, the RST as a follow-up exercise proved to be far more successful then the low-intensity exercises following the endurance exercise routines (Bailey et al., 2009).

Hence analyzing the results of the aforementioned study, the most important conclusion that can be made is the choice of the athlete on what they want to achieve for their bodies. If the athletes are looking to only reduce the FFA levels and increase overall muscle metabolism, then the standard routines of following a high-endurance exercise drill with a low-intensity exercise or aerobics routine would be best suited. However, if the athletes are looking for additional inputs like the increase in oxidation levels and/or speeds, then the low-intensity exercise or aerobics routine will not be suitable as backup-up exercise, instead the use of a customized and moderate-intensity RST routine would be most beneficent.

In a similar study, Jones and colleagues (2007), studied the overall impact that the endurance training exercise have on the over muscle activity. They analyzed and concluded that the impact that the high-intensity endurance training exercise routine would have on the muscle activity would be two fold:

1. Increase in the speed of the muscle phosphocreatine concentration (PCR) during the response stage of the exercise

2. Decrease in the overall magnitude of the slower sections and segments of the PCR muscle during the response stage of the exercise (Jones et al., 2007).

In their sample, they analyzed six male subjects between the ages of 6 and 25. These subjects went through a 5-week session of the low-intensity single-legged knee-extension endurance exercise training routine using the leg serving exercise as the element of control. This low-intensity exercise routine was always followed by high-intensity step exercise routines that lasted 6 minutes each and mainly encompassed the use of both legs simultaneously (Jones et al., 2007). The results of the study were as such:

The leg serving used as the control of element didn't experience much change during or after the extension or step exercises; however the training leg underwent numerous changes during and after the extension and step exercises. These changes included: increase in the time the individual had before reaching exhaustion levels during the extension exercise from a maximum of 19.6 minutes to 22.0 and a minimum of 1.6 minutes to 2.2 minutes during the extension exercise; the magnitude of the slower sections and segments of the PCR muscle experienced a decrease from a maximum of 15% to a maximum of 7% after the exercises (Jones et al., 2007).

Analyzing the result in the Jones et al. (2007) study, it is important to note that the sample is a very small sample and hence the results attained in the study cannot stand necessarily as true for varying circumstances and all athletes. Despite that fact it is also important to note that the combination of the step and extension exercises has a very positive impact on eth overall muscle activity and kinetics in the short run (Taylor and Bachman, 1999). It is safe to assume that the combination of these exercises will sustain high muscle kinetics in the long run as well. The aspects that need to be studied in future researches with the combination of the step and extension exercises is the impact t that they have on the muscle fat metabolism as well as the oxidation levels and speed of the legs.

In a comparative study, Klein and colleagues (1994) studied the overall fat metabolism ratios for endurance-trained and untrained men during low-intensity exercise routines. They sample a total of 10 men, 5 who were endurance-trained athletes and 5 who were untrained. They started off by calculating and analyzing the overall lipid activities and muscle activities while all 10 subjects were resting before the exercise routines began. They also calculated the free fatty acid (FFA) and glycerol rate of appearance (Ra) ratios. The calculated the lipid activities using indirect calorimetry as a determinant and the FFA and glycerol levels through the combination of glycerol (2H5) and palpitate (1-13C) one after another (Klein et al., 1994).

The results showed that the lipolytic reaction after 4 hours of high-intensity training routines showed no significant variations in the overall FFA and glycerol levels between the endurance-trained subjects (increase in a minimum of 1.02/kg to 3.76/kg and increase in a maximum of 9.85/kg to 24.64/kg) and the untrained subjects (increase in a minimum of 0.99/kg to 0.39/kg and increase in a maximum of 11.29/kg to 24.13/kg). The variation between the trained and untrained subjects occurred in the average triglyceride oxidation levels during the high-intensity exercise sessions. The trained subjects showed a high maximum of 7.51/kg and the untrained subjects showed a lowered maximum of 5.67/kg. Furthermore, during the recovery session of the exercises, the untrained subjects experienced a slower speed of decreased FFA and glycerol Ra levels in comparison with the trained subjects even though the overall decrease in the ratio was more or less similar as has been numerically exhibited above (Klein et al., 1994).

Analyzing the results of the above study, it is east to assert that the in spite of having similar FFA, lipolysis and glycerol levels, the endurance-trained individuals and athletes experience higher levels of fat burning then the untrained athletes. This is because they burn more fat tissues in their endurance exercise routines. Further analysis help us assert that the lipid activities get back to the baseline at a much slower rate for the untrained subjects then the male subjects.

In a separate and dissimilar study, Starling and colleagues (1996) took a different approach to analyzing the impact of endurance exercise by analyzing the impact that the diet of an individual has on his overall muscle triglyceride and endurance performance ratios. They took a sample of seven endurance-trained athletes who had the average of completing 120 minute cycling exercise with a maximum intake of oxygen at nearly 65% ratios. The diet changes introduced in the subjects daily routine included an intake of either a high-fat (Hi-Fat; with 68% of energy) or an isocaloric high-carbohydrate (Hi-CHO; with 83% of energy) diet for a total of 12-hour period. At the end of the 12 hours and after an overnight fast, the subjects went through an exercise routine of 1,600-kJ self-run cycling. Even though the muscle triglyceride levels before and after the cycling exercises were not so different before the new diet incorporation; the levels significantly increased for the Hi-Fat diet after it was incorporated into the daily intake of the athletes. The levels showed an increase in the minimum levels from 2.4 to 7.1 minutes and an increase in the maximum levels from 44.7 to 117.1 minutes for the Hi-Fat diet plans (Starling et al., 1996; see also Hochli et al., 1995; Morgan, 1992; McArdle et al., 1996c).