Reduction in blood flow to a muscle fiber would have the greatest effect on

Slow oxidative fibers

Explanation:

There are two main types of skeletal muscle and slow oxidative fibers are one of them.  

Slow oxidative   fibers are also called red fibers because they contain more blood-carrying myoglobin, which creates a darker appearance.

Red muscle fibres contract  more slowly than white fibers and generate    ATP by aerobic catabolism of glucose and fats.