Compex Technologies - a New Brighton, Minn.-based company specialising in products designed for pain relief and muscle rehabilitation - said Hamilton has been using its products regularly since the spring, reports ESPN.com.
Hamilton faces a possible ban because of a positive blood test at the Spanish Vuelta race two weeks after the Olympics. His Phonak team said both samples he provided showed evidence of an endurance-boosting blood transfusion.
Hamilton also had a preliminary positive test at the Athens Games, but the IOC dropped its probe because the cyclist's backup specimen was mistakenly frozen and there were insufficient red blood cells left to analyse. It meant Hamilton could keep his Olympic gold medal.
The former University of Colorado skier insists he is innocent and has vowed to clear his name.
Marshall Masko, vice president of marketing and sales for Compex, said the company is not worried about Hamilton's positive doping test.
"The jury is still out on all of that, so that does not concern us," Masko said.
"We have been working with him since early spring. He has used these products regularly since April."
