Cycling Science
Target Systems
The specific receptor, enzyme, transporter, or neuroendocrine axis that a compound directly modulates. This is the entity that adapts (or doesn't) — and therefore determines whether cycling is needed.
The single boolean that drives the entire engine
Every target system has one critical property: does it adapt? Systems that adapt (develop tolerance) require cycling. Systems that don't — substrates, cofactors, structural materials — can be dosed daily without diminishing returns. This single boolean drives the entire cycling engine.
Adapting Systems
20 systemsThese systems develop tolerance with sustained compound exposure. They require cycling (micro or macro) to maintain efficacy — and each has a measurable reset profile.
Adenosine A1/A2A receptors
adenosine-a1-a2a
Pathways through this system
Muscarinic M1 acetylcholine receptor
muscarinic-m1
Compounds targeting this system
Pathways through this system
Melatonin MT1/MT2 receptors
mt1-mt2
Compounds targeting this system
Pathways through this system
Serotonin 5-HT1A/2A receptors
5-ht1a-2a
Pathways through this system
GABA-A receptor
gaba-a
Compounds targeting this system
Pathways through this system
TrkA/TrkB neurotrophin receptors
trka-trkb
Compounds targeting this system
Pathways through this system
Dectin-1 beta-glucan receptor
dectin-1
Compounds targeting this system
Pathways through this system
α7 nicotinic acetylcholine receptor
nicotinic-alpha7
Compounds targeting this system
Pathways through this system
Acetylcholinesterase (AChE)
ache
Compounds targeting this system
Pathways through this system
Monoamine oxidase B (MAO-B)
mao-b
Compounds targeting this system
Pathways through this system
Aromatic L-amino acid decarboxylase (AADC)
aadc
Compounds targeting this system
Pathways through this system
Glutamate-cysteine ligase (GCL)
gcl
Compounds targeting this system
Pathways through this system
AMP-activated protein kinase (AMPK)
ampk-kinase
Compounds targeting this system
Pathways through this system
Sirtuin 1 (SIRT1) deacetylase
sirt1
Compounds targeting this system
Pathways through this system
Aromatase (CYP19A1)
cyp19a1-aromatase
Compounds targeting this system
Pathways through this system
HPA axis (CRH → ACTH → cortisol)
hpa-axis
Compounds targeting this system
Pathways through this system
HPG axis (GnRH → LH → testosterone)
hpg-axis
Compounds targeting this system
Pathways through this system
Keap1-Nrf2-ARE signaling complex
keap1-nrf2-are
Compounds targeting this system
Pathways through this system
NF-κB signaling complex
nfkb
Compounds targeting this system
Pathways through this system
Mitochondrial electron transport chain (Complex I–IV)
mitochondrial-etc-complex
Compounds targeting this system
Pathways through this system
Non-Adapting Systems
10 systemsThese systems do not develop tolerance. They are substrates, cofactors, or structural pools that benefit from consistent daily replenishment. No cycling needed.
SLC6A8 creatine transporter
slc6a8
Compounds targeting this system
Pathways through this system
TauT (SLC6A6) taurine transporter
taut-slc6a6
Compounds targeting this system
Pathways through this system
Cellular NAD+ pool
nad-pool
Pathways through this system
Collagen precursor substrate pool
collagen-substrate
Compounds targeting this system
Pathways through this system
Electrolyte/mineral pool (Na+, K+, Mg2+)
electrolyte-pool
Compounds targeting this system
Pathways through this system
Omega-3/SPM precursor pool
omega-spm-pool
Pathways through this system
Keratin precursor substrate pool
keratin-substrate
Pathways through this system
Enzymatic cofactor pool (Mg2+, Zn2+, B vitamins)
cofactor-pool
Compounds targeting this system
Pathways through this system
Vitamin D receptor (VDR)
vdr-nuclear
Pathways through this system
eNOS / nitric oxide vasodilation pathway
enos-no-pathway
Pathways through this system
Explore the system
See How It All Connects
Target systems are one layer of the cycling engine. Explore compounds to see their cycling schedules, or pathways to see how systems chain together.