Exercise as it relates to Disease/Fatty Liver and Aerobic Exercise
What is it?
Fatty liver is a condition that is diagnosed when over 10% of the livers weight is from fatty acids and triglycerides. The two types of fatty liver disease are alcoholic fatty liver disease (AFLD) and non-alcoholic fatty liver disease (NAFLD).
- Liver Biopsy - Gold standard, but unable to distinguish between AFLD and NAFLD, which needs to be determined by the assessor.
- Imaging Machines - Reliable for diagnosing moderate and severe cases.
- Serology - Not for diagnosing the condition itself, but for ruling out other possible conditions and diseases.
Causes and Risk Factors
AFLD is caused by the acute consumption of an excess of alcohol, and may develop into alcoholic hepatitis if lots of alcohol is consumed over a prolonged period. NAFLD has no direct pathogenic causes; however, there are risk factors and probable causes. It has been regarded as a manifestation of metabolic syndrome (insulin-resistance syndrome), so all of the associated risk factors may also influence NAFLD. The main factors include:
- Obesity, especially central/abdominal obesity
- Abnormal cholesterol levels (high triglycerides, or low high density lipoproteins)
Insulin resistance is one of the largest contributing factors due to its cascading effect on the liver:
- Blood glucose levels cannot be down regulated, and muscle glucose levels cannot be replenished
- Causes the mobilisation of free fatty acids and triglycerides to the target muscles and liver cells 
- The liver cannot synthesise glycogen or suppress gluconeogenesis, resulting in excess glucose production
- Excess glucose is unable to be aerobically metabolised from the increased insulin, and the exocytosis via very low density lipoproteins is suppressed, so some of it will be converted into more fats (de novo lipogenesis)
- As the fat builds up in the liver, without a way of using it, the body stores the excess energy in the hepatocytes, thus creating a fatty liver
Other risk factors that may lead or warn about a potential fatty liver include:
- Fat cell inflammatory proteins (adipose cytokines/adipokines)
- Rapid weight loss
- Some medications
Complications and Progressions
NAFLD is the broad term used for the condition of excess fat in the liver; however, there are different levels of severity:
- Fatty liver disease (steatosis) - term used when the liver contains excess fat, and there is no inflammation or scarring
- Non-alcoholic steatohepatitis (NASH) - the next progression on from steatosis, where the liver becomes inflamed and/or damaged
- Cirrhosis - a slowly progressing disease where permanent scar tissue slowly replaces the healthy liver tissue, which then impairs its functioning by blocking the blood flow through the liver. It hinders nutrients, toxins, hormaones, drugs and all other substances created in the liver
From NASH, the liver may take years or decades to progress any further, into a serious condition of cirrhosis, where there is permanent damage and scarring to the liver.
Effects of Aerobic Exercise
The main goal of aerobic exercise is to try to improve insulin resistance, and other factors that contribute towards metabolic syndrome.
- Insulin Resistance - exercise doesn't directly have an effect on insulin resistance, but it does influence abdominal fat, which is directly related to the resistance.
- Obesity - aerobic exercise for prolonged periods of time has been shown to utilise fat as the main fuel source. Where, the lower the intensity, the greater the contribution of fats for energy.
- Central Obesity - studies have shown that exercising aerobically will reduce the amount of abdominal fat, if completed regularly over time. Other studies have also found that central fat was decreased more than other areas of the body.
- Cholesterol - large decrease in the amount of triglycerides available in the plasma due to them being used as the main fuel source. High density lipoprotein levels also increase with aerobic exercise.
- Blood pressure/hypertension - aerobic exercise helps to lower blood pressure in both hyperintensive and normotensive individuals.
Recommendations and Interventions
If someone is suffering from AFLD, then they should stop consuming alcohol immediately and undergo abstinence to let their body fix itself. professional help may be needed to help the individual not to drink, and for any problems that my arise. Regular aerobic exercise is a great way to reduce and combat the precursor signs of NAFLD. The aerobic exercise should be:
- a low to moderate intensity so that they are predominately utilising their fat stores for fuel,
- continuous exercise bouts greater than 10 minutes minimum, to ensure benefits such as high density lipoproteins,
- and as often during the week as possible, 30 minutes on most if not all days.
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