Question explored with the scientific record
Conversation so far
- …started from a private conversation
- 1 what about viagra
- 2 could increase of bloodflow improve energy utilisation
Answered on this page ↓
could increase of bloodflow improve energy utilisation
Viagra does not improve energy utilization in a sedentary middle-aged adult with central adiposity. The evidence for that claim is thin and mostly from animal studies.
The retrieved studies show sildenafil can affect mitochondrial function in specific contexts. In rat heart mitochondria, sildenafil reduced hydrogen peroxide generation without changing how well the mitochondria made ATP [2]. In a rat burn model, sildenafil partially restored mitochondrial structure and ATP production that had been damaged by the burn [3]. In mouse skeletal muscle, sildenafil actually decreased the efficiency of ATP synthesis by about 40% [1]. That is the opposite of improved energy utilization.
The human studies in this retrieval test sildenafil in people with pulmonary hypertension or heart failure, not in healthy or sedentary adults. In patients with heart failure and preserved ejection fraction, sildenafil did not improve peak oxygen consumption (a direct measure of energy utilization during exercise) compared to placebo [8]. In healthy volunteers under low-oxygen conditions, sildenafil did not improve exercise capacity [4]. In COPD patients, it did not improve stroke volume or cardiac output [5].
The studies that show benefit are in people with damaged systems: pulmonary hypertension, burn injury, sickle cell disease with pulmonary hypertension [6, 7, 9, 10, 11, 12, 13]. Those are not your situation.
The mechanism question matters. Your central adiposity and sedentary pattern drive chronic sympathetic nervous system activation, which desensitizes your tissues to the signals that normally increase energy expenditure [14]. A drug that dilates blood vessels does not fix that. The root problem is not blood flow. It is that your cells have become resistant to the signals telling them to burn energy.
My call: sildenafil will not improve your energy utilization or metabolic health. The evidence shows it can help mitochondrial function in damaged tissue but does not improve exercise capacity or energy efficiency in healthy or sedentary people. The real intervention for your profile is movement and diet, not a vasodilator. Confidence: moderate.
Sources used 14
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Nitric Oxide Regulates Skeletal Muscle Fatigue, Fiber Type, Microtubule Organization, and Mitochondrial ATP Synthesis Efficiency Through cGMP-Dependent Mechanisms
This study shows that nitric oxide signaling through soluble guanylate cyclase 1 (GC1) modulates skeletal muscle fatigue resistance, fiber-type specification, subsarcolemmal microtubule organization, and mitochondrial ATP synthesis efficiency, with GC1 acting in a nNOS-dependent…
DOI: 10.1089/ars.2016.6630 -
Sildenafil citrate concentrations not affecting oxidative phosphorylation depress H2O2 generation by rat heart mitochondria
This study investigates the effects of sildenafil citrate on rat heart mitochondrial function, revealing that it does not significantly impact mitochondrial bioenergetics or calcium-induced permeability transition but reduces hydrogen peroxide generation, suggesting a potential …
DOI: 10.1007/s11010-007-9645-9 -
Burn-Induced Cardiac Mitochondrial Dysfunction via Interruption of the PDE5A-cGMP-PKG Pathway
In a rat model of severe burn, burn-induced cardiac mitochondrial dysfunction occurs via interruption of the PDE5A-cGMP-PKG pathway, and sildenafil partially or fully preserves mitochondrial structure, replication, respiration, and ATP production, mitigating burn-associated card…
DOI: 10.3390/ijms21072350 -
Sildenafil does not Improve Exercise Capacity under Acute Hypoxia Exposure
This study investigates the effects of sildenafil on exercise capacity and various physiological parameters in healthy young volunteers during acute hypoxia, finding no significant improvements in performance or cardiovascular and respiratory responses.
DOI: 10.1055/s-0035-1559774 -
Acute effects of sildenafil on exercise pulmonary hemodynamics and capacity in patients with COPD
This study investigates the acute effects of sildenafil on pulmonary hemodynamics and exercise capacity in patients with chronic obstructive pulmonary disease (COPD), finding that while sildenafil attenuates the increase in mean pulmonary artery pressure during submaximal exerci…
DOI: 10.1016/j.pupt.2008.01.012 -
The Efficacy and Safety of Sildenafil in Patients With Pulmonary Arterial Hypertension Associated With the Different Types of Congenital Heart Disease
This study investigates the efficacy and safety of sildenafil in improving exercise capacity and hemodynamics in patients with pulmonary arterial hypertension associated with different types of congenital heart disease.
DOI: 10.1002/clc.20917 -
Sildenafil Citrate Therapy for Pulmonary Arterial Hypertension
This study demonstrates that sildenafil citrate significantly improves exercise capacity and hemodynamics in patients with pulmonary arterial hypertension over a 12-week period, compared to placebo.
DOI: 10.1056/NEJMoa050010 -
Effects of sildenafil on invasive haemodynamics and exercise capacity in heart failure patients with preserved ejection fraction and pulmonary hypertension: a randomized controlled trial
A single-centre, randomized, double-blind, placebo-controlled trial showing that sildenafil does not reduce invasive pulmonary artery pressures or improve exercise capacity in HFpEF patients with pulmonary hypertension, though PAWP decreased more with placebo; overall no clinica…
DOI: 10.1093/eurheartj/ehv336 -
Addition of Sildenafil to Long-Term Intravenous Epoprostenol Therapy in Patients with Pulmonary Arterial Hypertension
This study investigates the efficacy of adding oral sildenafil to long-term intravenous epoprostenol therapy in patients with pulmonary arterial hypertension, demonstrating significant improvements in exercise capacity and hemodynamic measurements.
DOI: 10.7326/0003-4819-149-8-200810210-00004 -
Oral Sildenafil Therapy for Chinese Patients With Pulmonary Arterial Hypertension: A Multicenter Study
This multicenter study demonstrates that oral sildenafil therapy significantly improves exercise capacity, dyspnea scores, and hemodynamic parameters in Chinese patients with pulmonary arterial hypertension over a 12-week period.
DOI: 10.1177/0091270011398241 -
Sildenafil improves hemodynamic parameters in COPD—an investigation of six patients
This study investigates the effects of sildenafil on hemodynamic parameters and exercise capacity in six patients with severe COPD and pulmonary hypertension, demonstrating significant improvements in pulmonary arterial pressure and walking distance after treatment.
DOI: 10.1016/j.pupt.2005.09.006 -
Long-term Treatment With Sildenafil Citrate in Pulmonary Arterial Hypertension
The SUPER-2 study evaluates the long-term safety and efficacy of sildenafil citrate in patients with pulmonary arterial hypertension, demonstrating that the treatment is generally well tolerated and leads to improvements in functional status and exercise capacity over three year…
DOI: 10.1378/chest.10-0969 -
Sildenafil therapy in patients with sickle cell disease and pulmonary hypertension
Open-label, early-phase study showing that chronic sildenafil therapy is safe and improves pulmonary artery pressures and exercise capacity in adults with sickle cell disease and mild-to-moderate pulmonary hypertension, supporting further randomized trials.
DOI: 10.1111/j.1365-2141.2005.05625.x -
Chronic Sympathetic Activation
This perspective proposes that age-associated sympathetic nervous system activation, driven by increasing adiposity via leptin and insulin signaling, paradoxically reduces rather than augments β-adrenergic thermogenesis through receptor desensitization, potentially creating a vi…
DOI: 10.2337/diabetes.53.2.276