kPCr (muscle oxidative capacity)
Metabolic / mitochondrial
Choi et al. 2016; regression line digitized from Figure 2.
Research & Evidence Physiological reserve
Exploratory evidence synthesis
Physiological reserve across adulthood.
Selected measures of sleep, autonomic regulation, muscle metabolism and maximal exercise are shown on one age-normalized reference frame.
The comparison is designed to make research questions visible, not to imply that the systems share a proven cause.
Hover over a line to view its age and relative value. Shaded regions reflect source-specific uncertainty or reconstruction ranges and should not be interpreted as directly comparable confidence intervals.
What the figure shows
Published cross-sectional patterns brought onto a common age-30 reference—not within-person decline or a causal model.
Working question
Could age-related changes in CB1 signaling contribute to coordinated changes in adaptive physiology across systems?
Evidence boundary
The figure generates testable questions. It does not establish that CB1 change causes any displayed trajectory.
Methods & interpretation
A common frame, with source-specific limits.
Each series is normalized to its age-30 reference. Some trajectories are reconstructed from fitted lines in published figures; others use published normative reference ranges, age-bin percentiles or regressions reconstructed from rounded group summaries.
Age coverage differs by source. Lines stop where the underlying data no longer support a reasonable estimate. The CB1 panel is deliberately adjacent rather than integrated into the multi-system overlay: it provides context for a hypothesis, not evidence of causal linkage.
Trajectory notes
SWS (EEG slow-wave sleep)
Sleep architecture
Ohayon et al. 2004; fitted curve reconstructed from the published figure.
RMSSD (autonomic variability)
Autonomic regulation
Umetani et al. 1998; central values reconstructed from age-specific 95% reference limits using geometric midpoints.
N2 central spindle density
Sleep microstructure
Sun et al. 2023 supplement; sex-specific smoothed 50% ranges converted to sex-balanced midpoints.
N3 relative delta power (1–4 Hz)
Sleep microstructure
Sun et al. 2023 supplement; sex-specific smoothed 50% ranges converted to sex-balanced midpoints.
Sleep efficiency (first-night PSG model)
Sleep architecture
Boulos et al. 2019; continuous mixed-effects age trajectory, standardized to first-night PSG.
VO₂max (direct CPET, population reference)
Cardiorespiratory performance
FRIEND registry; sex-specific 50th percentiles interpolated and averaged after age-30 normalization.
Maximal fat oxidation (exercise MFO, trained women)
Metabolic / mitochondrial
Dahlgaard Hansen et al. 2024; regression reconstructed from rounded group summaries and R².
Peak cardiac index (maximal exercise)
Cardiorespiratory performance
Pandey et al.; regression line digitized from Figure 3B. Series terminates within the cohort age range.
Primary literature anchors
Choi et al. (2016) ↗
Muscle PCr recovery and gait speed, Baltimore Longitudinal Study of Aging.
Ohayon et al. (2004) ↗
Meta-analysis of quantitative sleep parameters across the lifespan.
Umetani et al. (1998) ↗
Twenty-four-hour time-domain heart-rate variability and age.
Sun et al. (2023) ↗
Normative lifespan sleep EEG references, including spindle density and delta power.
Boulos et al. (2019) ↗
Normative polysomnographic sleep efficiency across adulthood.
Dahlgaard Hansen et al. (2024) ↗
Maximal fat oxidation across the adult lifespan of trained women.
Mato et al. (2003) ↗
CB1 receptor density and G-protein activity in human frontal cortex across age.
Version 0.1 · reconstructed September 2026. Values displayed here are reconstructed from published figures or reference material unless a source note states otherwise. This page is for scientific discussion and does not provide medical advice.