Cellular energy is adaptable,
not permanently fixed

Ageing can influence mitochondrial respiration, aerobic capacity, muscle mass and the speed at which the body recovers from demanding work. These changes are real, but they are not identical in every person and they do not mean that cellular energy capacity can only move in one direction.

Human training studies show that adults over 65 can increase mitochondrial proteins, oxidative capacity, cardiorespiratory fitness and strength. The most reliable improvements come from repeated biological demand, followed by enough recovery for the body to adapt. In practical terms, that means exercise remains the central intervention.

Exercise changes the system
from the inside

Exercise increases cellular demand for ATP. That demand activates signalling pathways that influence mitochondrial protein synthesis, enzyme activity, oxygen use and network structure. Different forms of exercise create different signals, so the most complete strategy normally combines aerobic and resistance work.

Build the signal,
then allow the adaptation

More exercise is not automatically better. Cellular adaptation depends on a repeatable dose that can be recovered from. Someone returning after years of inactivity needs a different starting point from an experienced athlete.

• Begin with consistency: establish regular walking or low-impact aerobic work before chasing maximal intensity.
• Train strength: use progressive resistance for the major movement patterns, adjusted for technique, joints and experience.
• Add intensity gradually: intervals can be useful, but hard sessions need spacing and should not dominate every workout.
• Protect recovery: sleep, sufficient energy intake and sensible training volume determine whether repeated stress becomes adaptation or accumulated fatigue.
• Reassess unexplained fatigue: a sudden or persistent fall in energy may require medical investigation rather than harder training.

Creatine supports a specific
ATP buffer

Creatine is often grouped with general “energy supplements”, but its best-established role is more precise. Stored phosphocreatine donates a phosphate group to ADP, helping regenerate ATP during short, repeated, high-power efforts. This is particularly relevant to resistance training, sprinting and repeated bursts of work.

Creatine does not replace mitochondrial adaptation and it is not a stimulant. Its value is strongest when paired with progressive training. Human trials in older adults have reported additional gains in lean tissue, selected strength measures and training performance, although not every outcome improves in every study.

Biomarkers can change
without proving an energy benefit

NAD+ is essential to energy metabolism, and nicotinamide riboside (NR) is a dietary precursor within the NAD+ pathway. Human trials show that oral NR can raise blood NAD+ metabolites and alter the skeletal-muscle NAD+ metabolome. That is meaningful biological evidence, but it is not the same as proving that everyone will feel more energetic, perform better or live longer.

Not every energy problem
is a mitochondrial problem

Persistent fatigue can be associated with sleep disorders, iron or vitamin deficiencies, thyroid conditions, infection, mood disorders, medication effects, cardiovascular or respiratory disease, inadequate food intake and many other causes. A supplement stack cannot safely diagnose these possibilities.