GW842166X is primarily utilized in research settings as a potent and selective agonist for the peroxisome proliferator-activated receptor delta (PPARδ). It is extensively studied for its potential role in modulating metabolic pathways, particularly in the context of lipid metabolism and energy homeostasis. Researchers use it to investigate the effects of PPARδ activation on conditions such as obesity, diabetes, and metabolic syndrome. Additionally, it is employed in preclinical studies to explore its impact on muscle endurance, oxidative capacity, and inflammation, making it a valuable tool for understanding the therapeutic potential of PPARδ modulation in various diseases.