Damaged connective-tissue paths may spread failure between otherwise capable muscle regions

The train of thought that ends in this hypothesis. Each stage is the reason the next exists. The master question narrows to a goal, the goal to an unknown nobody has closed, the unknown to the hypothesis proposed here. Every step below says what it rests on and what carries it.

Two live hypotheses pull in opposite directions here, and the field has not chosen between them.

Does rehabilitation restore capacity yet accelerate later decline in older people whose symptoms worsen with exertion after infection?

The engine's own statement of the hypothesis, in full.

CROSS-DOMAIN TRANSFER, unverified: In a subset of aging humans with postinfectious exertional intolerance, rehabilitation could restore reproducible regional force contributions while leaving a damaged connective-tissue path that mechanically couples those regions vulnerable. A localized path event during later ordinary activity could propagate failure among otherwise capable linked regions, causing residual loss despite genuine early aggregate gain. The proposed state is demonstrable shared load-bearing architecture, not correlation caused only by a common high-demand bout, global perfusion or recruitment. Reducing that path-specific cofailure could improve SPV_5 if it materially reduces recurrent loss while useful force is retained. The conservative benefit scenario of no greater marginal loading, reduced independence or compensating harm elsewhere is retained; it is not a demand to equalize post-event local loads. Whether a change permitting some greater local loading has a favorable net functional and injury tradeoff remains unknown. Regional strength, redundancy, retention probability and long-term aging preservation are distinct quantities.

Every other hypothesis the engine wrote for the same gap, and the observation that would separate the two.

• Rival 01 of 03

  Sequence errors in new muscle proteins may shorten their working life and cause later force loss

  Not yet published.

  What would separate them

  Sequence errors in new muscle proteins may shorten their working life and cause later force loss predicts: Under shared_conditions and the time-indexed effect definition in competition_interpretation, excess independently confirmed amino-acid sequence errors in dated new contractile material must precede loss of function or removal of those same incorporated proteins and delayed force decline. Quantify absolute erroneous and correct abundance by protein and sequence site, defective fraction, intact incorporation, initial mechanical contribution and subsequent functional and physical survival. The conditional burden-to-force assumption is that the affected sites and amount, together with their contribution and loss, can account for a material part of muscle-level residual loss beyond baseline pathology; no universal error-frequency threshold or linear mapping is assumed. Detection of a rare error alone does not establish consequential burden, and rarity alone does not exclude it: affected sites, intact mechanical contribution and subsequent functional loss must determine relevance. First establish a feasible way to link the same error-bearing intact structures to initial mechanics and later fate; whole-muscle early gain alone does not do this. Distinguish force failure before removal from removal of still-competent material, protective quality control, dilution, heterogeneous fiber loss and replacement, and measure the removal-to-functional-replacement balance. If this structure-level linkage cannot be established, retain that causal step as unverified. Stable-isotope labeling dates synthesis; it does not identify mistranslation or distinguish degradation from dilution. The ordinary alternative at the same initial states, imposed tolerated demands and times is abnormal folding, assembly, oxidation or removal of correct-sequence proteins during incomplete recovery without antecedent mechanically consequential sequence-error excess. Only if a state-preserving preparation and a sufficiently selective correction become feasible, define t0 before correction and compare the total subsequent effect of lower verified error production with the control trajectory. Record pre-t0 total synthesis, protein composition, folding/assembly, degradation, energetics, actual work history, viable mass, existing injury and competing causes, and use a comparable independently imposed demand schedule where feasible. Verify error reduction before its proposed consequences. Assess direct tool effects on synthesis amount/composition, assembly, degradation, metabolism, force or viability that bypass error reduction; if they cannot be separated, any rescue identifies only a total intervention effect, not a fidelity-specific effect. In contrast, changes after t0 in assembly/folding, removal, energetics, achieved work, viable mass or force caused by fewer errors are legitimate mediators or outcomes of the total fidelity effect and must not be matched away. Measure their trajectories and distinguish them by time order and, only if feasible, orthogonal controls or staged interventions. A controlled direct-effect comparison fixing a specified mediator history is an additional question only if independently manipulable with adequate overlap and without introducing new injury; inability to fix it does not refute the total mechanism. Reduced imposed demand or direct suppression of contraction is separately reported, not presented as exposure-preserving fidelity rescue. Existing erroneous material may need replacement, so immediate full recovery is not required. Normal fidelity at sufficient site/protein coverage, sensitivity and timing, with bounds excluding a burden capable of the observed loss, weakens this mechanism locally. Rescue through lower strain, downstream chemistry or pathogen suppression can preserve defective material or remove an upstream driver, and does not refute a fidelity contribution or establish a different pure model.

• Rival 02 of 03

  Contraction-released heme iron may sustain lipid damage and delay muscle recovery
  What would separate them

  Contraction-released heme iron may sustain lipid damage and delay muscle recovery predicts: Under shared_conditions and the time-indexed effect definition in competition_interpretation, identify an endogenous physiological species and compartment: distinguish heme retained in protein, released heme-associated catalyst and any subsequent conversion to dissociated nonheme iron. No one readout substitutes for another; source, accessibility, concentration, conversion kinetics and contraction threshold remain unknown. Conditional on their identification and artifact-controlled preservation, the implicated catalytic rise must precede newly forming lipid oxidation and injury. Quantify formation separately from clearance and follow new oxidative flux after contraction and before delayed force loss. Measure or bound fresh initiation from inflammation, mitochondrial dysfunction, ischemia/reperfusion, mechanical disruption and peroxide breakdown, together with propagation and termination in the relevant compartment. Operationally, the stronger autonomous version predicts continuing consequential new damage over a specified post-initiation window after the initiating contraction ends and continuing external initiation is absent or bounded too small to explain the flux under an explicit kinetic model. Internal catalyst/substrate/peroxide cycling must be specified within that model rather than silently counted as zero initiation. No duration or quantitative bound is supplied. If ongoing initiation cannot be bounded or independently varied, autonomy is unidentified; an input-dependent chemical amplifier remains possible. The ordinary alternative predicts continued insults or slowly cleared products without the proposed preceding catalytic transition. For a future delayed interruption define t0 after the documented initiating history and before intervention. Compare pre-t0 actual work and imposed demand, viable mass, force, injury, catalyst state and productive pathogen burden, then estimate the total subsequent protection from target-engaged interruption against its control under a comparable independently imposed demand schedule where feasible. Measure compartment-level target engagement and new oxidation before subsequent injury and force change. Direct tool actions on metabolism, contraction, host defense or pathogen growth that bypass the intended catalytic change are alternative intervention pathways requiring specific controls if feasible; if unresolved, rescue alone cannot attribute protection to the proposed catalyst. Changes after t0 in viability, injury, force, achieved work, inflammation or pathogen burden caused by chemical protection or feedback belong to the total effect and must not be matched away. Do not require subsequent viability or injury equality to test preservation. A changed imposed load or direct contractile impairment is reported separately as an exposure tradeoff. A contrast holding specified later infection or injury trajectories fixed concerns a narrower controlled direct effect and is attempted only when independently feasible with overlap; it is not a prerequisite for the total amplifier effect. Convergent sequestration and independently acting chain termination support attribution only after target engagement and direct off-target routes are examined, not simply because both rescue. Conditional restoration must reproduce the identified physiological species, localization, concentration and timing; bulk toxic iron addition is not a validating reversal. Relate the amount and duration of new oxidation to subsequent force loss and the fraction of recovery delay/residual loss, with useful adaptation and defense assessed. Lower products without less injury or functional loss are insufficient. Iron dependence can identify a downstream amplifier without autonomy or exclusion of mechanical/infectious causes. Adequate sensitive negative tests constrain the specified compartment/window only and do not establish a rival.

• Rival 03 of 03

  Rebuilding after exertion may enable a tissue pathogen reservoir to produce new pathogens
  What would separate them

  Rebuilding after exertion may enable a tissue pathogen reservoir to produce new pathogens predicts: Under shared_conditions and the time-indexed effect definition in competition_interpretation, first identify an organism and an anatomically constrained viable reservoir, with an organism/assay-specific upper bound on low or nonproductive baseline output and a predeclared site/window. No organism, site or threshold is supplied. Demonstrate linkage of genuinely new productive output to that same reservoir rather than another site or new exposure. A specified rebuilding-associated host change must precede the rise, followed by local injury and delayed loss despite genuine early adaptation. Repeat this ordering across natural tolerated episodes and quantify output burden, recurrence, injury and functional magnitude. Organism-appropriate orthogonal assays must distinguish productive output from persistent nucleic acid, static antigen, abortive expression, noninfectious particles, redistribution and fragments released after damage. The ordinary alternative at the same initial states, tolerated demands and times permits sterile immune injury and fragments, already active or independently fluctuating infection, reinfection, or stress/immune-containment changes without rebuilding as a gate. Separate two causal questions. For the total effect of suppressing demonstrated new productive output, define t0 before suppression; compare pre-t0 reservoir/output history, host rebuilding, synthesis/fidelity, inflammation, metabolism, mechanics, catalytic state, viable mass, force and work history, with comparable independently imposed demand where feasible. Only after an observed transition, a state-preserving contained preparation and a sufficiently selective pathogen-specific perturbation exist does reduced output followed by reduced new injury support infection-dependent protection. Direct drug effects on inflammation, metabolism, rebuilding, fidelity, mechanics, chemistry, viability or contraction that bypass output reduction must be assessed and separated where possible; otherwise a rescue is only a total intervention effect. In contrast, downstream changes caused by lower infection in those same host variables, including subsequent achieved work, viable mass and force, are intended mediators or outcomes and are included in the total infection effect. Reduced downstream inflammation or catalysis is compatible with infection causality, not a specificity failure. Do not require post-suppression host fidelity, mechanics, chemistry or force to remain equal. Controlled direct-effect contrasts fixing specified host mediators are additional questions only if independently feasible with overlap. Record any changed imposed activity exposure separately. For the distinctive rebuilding gate, output suppression alone is insufficient. A preparation must retain the same viable reservoir-host transition. Identify the proposed rebuilding change and, only if possible, selectively vary it before productive output while comparing pre-gate stress, injury, immune containment, nutrient availability and baseline host/organism capacity. Determine whether gate-associated changes act through an explicitly specified permissiveness pathway or are independently caused alternatives; measure their trajectories without automatically matching away any proposed gate mediator. A manipulation merely reducing general replication capacity or host survival does not identify a rebuilding gate. If rebuilding cannot be separated from its covarying alternatives, keep the gate unverified even if infection-dependent injury is supported. Conditional restoration must reproduce the same host-state transition and organism; fragments or an unrelated imposed infection cannot validate it. Existing damage need not reverse immediately. A verified reduction in output without less new injury over an adequately sensitive causal window constrains ongoing dependence locally, not all historical infection effects. Negative samples constrain the named organism, site, sensitivity and window, not every reservoir and not a rival. Susceptibility, safe duration, relapse after withdrawal, host defense and activity-preserving net benefit remain unknown.

Which of the figures above have a study behind them, which are the engine's own, and what it would take to refute the hypothesis. This audit never judges the idea.