GLOSSARY

Ca²⁺-ATPase couples active calcium transport to ATP hydrolysis.

ATP-producing and ATP-consuming enzymes operate together. Creatine kinase supports reversible phosphoryl transfer involving phosphocreatine and nucleotides, while ion pumps expend energy to maintain gradients. Kinase activity is not equivalent to dietary creatine content or an automatic supplement requirement. In muscle, preserving excitability and handling calcium matter alongside fuel provision for contraction and subsequent relaxation, so energy supply cannot be interpreted independently of the work consuming it.

ATP links energy transfer to cellular work and must be continually regenerated during activity. Existing stores do not sustain prolonged work; phosphocreatine, glycolysis and oxidative processes contribute to renewal. ADP and AMP belong to the adenylate network rather than being mere waste. One nucleotide's amount is not total food calories or stored fuel volume. Continuous turnover matters more than imagining a large isolated ATP tank powering an entire session.

Phosphorylation adds phosphate and dephosphorylation removes it, altering signaling or metabolism according to the molecule. Substrate-level ATP formation transfers phosphate directly, while oxidative formation uses membrane machinery and a gradient. The shared phosphorylation name does not mean identical enzymes or conditions. Normal phosphate functions do not establish extra dietary phosphate requirements for every workout or guarantee that a supplement increases cellular ATP formation independently of fuel and regulation.