Short- term effects of a single bout of moderate physical activity on liver fat content and validation of ultrasonography method after exercise

Non alcoholic fatty liver disease (NAFLD) represents a spectrum of liver
diseases, including steatosis, non-alcoholic steatohepatitis (NASH) and
cirrhosis . The accumulation of lipids in the liver causes: insulin resistance,
overproduction of glucose and Very Low Density Lipoprotein (VLDL), resulting in
hyperglycemia, hypertriglyceridemia and low levels of HDL cholesterol.
According to the American Association for the Study of Liver Disease, NAFLD is
defined as: liver fat exceeding 5 to 10% of total liver weight. NAFLD seems to
be related to obesity, one third of the patients with NAFLD is obese {Colles,
2006 7 /id}.There is increasing evidence that NAFLD is the new component of the
metabolic syndrome. This clustering of risk factors is associated with an
increased risk of cardiovascular disease and type 2 Diabetes Mellitus. The most
appropriate treatment for hepatic steatosis is still uncertain. Most research
intervention studies focus on weight reduction strategies to manage NAFLD. A
combined study of restricted diet an exercise in obese patients with fatty
liver, had beneficial effects, the degree of steatosis were significantly
decreased. It is still unclear if exercise independent of weight loss
influences liver fat content and what the short-term effects are.

In this study we will examine the short-term effects of a single bout of
physical activity on liver fat content. Research question: What are the short-
term effects of a single bout of moderate physical activity on liver fat
content? Can the ultrasonography method to quantify liver fat, be used after
exercise? And what is the validity? Can a decrease in liver fat values be
explained by volume overload of the liver?

Selection of Volunteers: In the pilot trial we will study 16 obese volunteers.
- Pretests • VO2 max test: One week before the intervention cardio respiratory
fitness will be assessed with a maximal exercise tolerance test on an
electrically braked bicycle ergometer. Food diary need to be kept 3 days before
intervention. • Antopometry: Body weight, waist circumference, hip
circumference • Blood sampling: we will measure the following markers: Glucose,
ALT, AST, LDL cholesterol, HDL cholesterol, triacylglycerol, acetoacetaat, beta
hydrixybutaat, lactaat, pyrovaat and glyceriden • Ultrasonography will be used
to determine : fat content, visceral and subcutaneous fat Echo 1 ( pre-
intervention) MRI 1 to validate liver fat values. • Intervention Bicycle
ergometry. The volunteers need to complete 60 minutes of bicycle ergometry at
55% of their predetermined Vo2 max, RER values will also be used to control the
intensity. • Bloodsampling - Post tests Echo 2 (immediatly after exercise) MRI
2 • Echo 3 MRI 3 • Echo 4

Intervention Bicycle ergometry The volunteers need to complete 60 minutes of
bicycle ergometry at 55% of their predetermined Vo2 max, RER values will also
be used to control the intensity

Ultrasonography is non-invasive technique, used in the UMCG every day for many
times. - MRI is considered to be a save research technique. - Blood samples
will be taken by educated and experienced employees of the Clinical laboratory
of the UMCG. - The VO2max test and intervention will be performed under the
supervision of a medical doctor of the department of sports-medicine. In case
of any abnormalities the intervention will be stopped. Here fore, we consider
the risks of the study to be small.