Answer
The transformation of glucose to lactate occurs when Myocytes are low in oxygen, and it provides a means of generating ATP under $O_{2}$-deficient conditions.
Because lactate can be oxidized to pyruvate, glucose is not wasted; pyruvate is oxidized by aerobic reaction when $O_{2}$ becomes plentiful. This metabolic flexibility gives the organism a greater capacity to adapt to its environment.
Work Step by Step
No, anaerobic glycolysis in muscle is not a wasteful use of glucose.