Figure 6. Proposed mechanism of AMPK activation by estrogen.

Females have higher levels of circulating estrogen, which can bind estrogen-receptor β activating an influx of Ca²⁺ into the cell, stimulating Ca²⁺/Calmodulin-dependent protein kinase kinase β (CaMKKβ) phosphorylation of AMPK. At this point, anabolism is halted, and catabolism is stimulated resulting in the transport of fatty acids into the mitochondria, via carnitines, to perform β-oxidation. Differences in regulation of carnitine and lipid species between male and female participants may reflect reliance on different metabolic mechanisms, like estrogen activation of AMPK, and substrates for energy demands post-injury.