Investigating A Dose Response Relationship between High Fat Diet Consumption and the Contractile Performance of Isolated Mouse Soleus, EDL and Diaphragm Muscles

Purpose
Recent evidence has demonstrated an obesity-induced, skeletal muscle-specific reduction in contractile performance. The extent and magnitude of these changes in relation to total dose of high-fat diet consumption remains unclear. This study aimed to examine the dose–response relationship between a high-fat diet and isolated skeletal muscle contractility.

Methods
120 female CD1 mice were randomly assigned to either control group or groups receiving 2, 4, 8 or 12 weeks of a high-calorie diet (N = 24). At 20 weeks, soleus, EDL or diaphragm muscle was isolated (n = 8 in each case) and isometric force, work loop power output and fatigue resistance were measured.

Results
When analysed with respect to feeding duration, there was no effect of diet on the measured parameters prior to 8 weeks of feeding. Compared to controls, 8-week feeding caused a reduction in normalised power of the soleus, and 8- and 12-week feeding caused reduced normalised isometric force, power and fatigue resistance of the EDL. Diaphragm from the 12-week group produced lower normalised power, whereas 8- and 12-week groups produced significantly lower normalised isometric force. Correlation statistics indicated that body fat accumulation and decline in contractility will be specific to the individual and independent of the feeding duration.

Conclusion
The data indicate that a high-fat diet causes a decline in muscle quality with specific contractile parameters being affected in each muscle. We also uniquely demonstrate that the amount of fat gain, irrespective of feeding duration, may be the main factor in reducing contractile performance.