Chronic liver disease (CLD), often caused by Hepatitis C, is the 10th-leading cause of death in America, according to a 2001 study appearing in the journal American Family Physician. Furthermore, according to Science Daily, up to 30 per cent of the U.S. adult population and the majority of obese people have nonalcoholic fatty liver disease (NFLD), a condition that can lead to liver failure in serious cases. Fortunately, physical exercise promotes healthy liver function and can help combat liver disease.
Effect in patients with hepatitis C
A 2002 study published in the gastroenterology journal Gut studied the effects of a 12-week diet and exercise programme on the liver function of patients with Hepatitis C virus (HCV). The study found an association between weight loss and improved liver function in patients with HCV, including a reduction in fibrosis - a condition common to CLD patients that may ultimately result in cirrhosis, according to The Journal of Clinical Investigation - and reduction in abnormal liver enzymes.
Effect on fatty livers
At least two studies have demonstrated positive effects of exercise on treating fatty liver, or NFLD. A 1997 study conducted by Japanese researchers studied the effects of a three-month exercise programme, including walking and jogging, on obese subjects with fatty livers. After the trial, programme participants' blood and liver histology data showed a significant decrease in steatosis (liver fat) compared to their pre-trial data and compared to that of a control group. A similar trial that studied the effects of aerobic exercise on liver function of obese men and women, published in the journal Hepatology in 2009, found that exercise helped reverse NFLD even in participants who did not lose any weight.
Effect on liver blood volume
Scientists have also studied the effects of exercise on the liver function of healthy individuals. A study published by the American Heart Association in 1990 found that during upright exercise, healthy individuals experience a decrease in blood flow to the liver, demonstrating how abdominal organs compensate for the increased blood flow to the lungs and legs during upright exercise.
Effect on liver ATP
Exercise may also affect the liver's metabolic function, according to a 1999 study conducted on rats. This trial, published in the Archives Of Physiology And Biochemistry measured levels of ATP - or adenosine triphosphate, an enzyme that serves as a source of energy for cellular reactions - in rats after exercise. The study found decreased liver ATP levels in the rats after exercise, concluding that exercise may result in metabolic adaptations to the liver.
Effects on diabetic livers
A study published by The Journal of Clinical Endocrinology & Metabolism in 2005 indicates the positive effects of exercise on the liver function of diabetic patients. In this trial, a two-week diet and exercise programme was shown to reduce insulin sensitivity and decrease fatty lipids in the livers of patients with Type 2 diabetes.
- Gut: Effect of weight reduction on liver histology and biochemistry in patients with chronic hepatitis C.
- The Journal of Clinical Investigation: Liver fibrosis
- Journal of Hepatology: Therapeutic effects of restricted diet and exercise in obese patients with fatty liver
- Hepatology: Aerobic exercise training reduces hepatic and visceral lipids in obese individuals without weight loss
- Archives of Physiology and Biochemistry: Effects of physical exercise on liver ATP levels in fasted and phosphate-injected rats
- JCEM: Effects of diet and exercise on muscle and liver intracellular lipid contents and insulin sensitivity in type 2 diabetic patients
- American Family Physician: Preventive strategies in chronic liver disease: part 1
- Science Daily: Regular aerobic exercise reduces health concerns associated with fatty liver
- AHA: Redistribution of regional and organ blood volume and effect on cardiac function in relation to upright exercise intensity in healthy human subjects