l carnitine time kick in L-Carnitine – L-carnitine can boost your endurance...

Evidence has shown that L-carnitine can promote mitochondrial biogenesis by upregulating peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1), a master regulator of mitochondrial biogenesis [14] and that L-carnitine promotes mitochondrial protein acetylation, a chemical modification that improves mitochondrial function and protects against stressors

L-Carnitine is also good for periods of bulking as it limits fat gains, making for a cleaner bulk.

Pilz, S., Frisch, S., Koertke, H., Kuhn, J., Dreier, J., Obermayer-Pietsch, B., Wehr, E., & Zittermann, A

(1997): Changes in dopamine receptor mRNA expression following chronic mild stress and chronic antidepressant treatment