Apunts. Medicina de l'Esport

Apunts. Medicina de l'Esport

Volume 51, Issue 189, January–March 2016, Pages 27-35
Apunts. Medicina de l'Esport

Review
Can sildenafil improve physical performance at altitude? Current scientific evidence¿Afecta sidenafilo a la capacidad física en altitud? Evidencias científicas en la actualidad

https://doi.org/10.1016/j.apunts.2015.11.001Get rights and content

Abstract

Sildenafil has proven to efficiently reduce the increase in pulmonary artery pressure provoked by hypoxic pulmonary vasoconstriction. However, its role as a possible factor in increasing exercise performance under hypoxic conditions remains to be demonstrated. The use of sildenafil has increased among mountaineers, not as a high altitude pulmonary edema preventive drug, but as a means that could help to improve performance. Several studies have attempted to address this issue, with conflicting results. Currently, despite the inconclusive data at simulated or real altitude, and with the clear evidence that, in normoxia, sildenafil does not improve performance, this drug is being used (and sometimes overused) by people who climb high peaks. However, such potential performance improvement would depend on the degree of hypoxemia (altitude) and the individual responsiveness to this drug. This paper reviews the current knowledge on this matter.

Resumen

Sildenafilo ha demostrado eficacia reduciendo la hipertensión pulmonar provocada por la vasoconstricción pulmonar hipóxica. Su papel como posible factor para aumentar el rendimiento en el ejercicio en condiciones de hipoxia está por demostrar, pero el uso de sildenafilo ha aumentado entre los montañeros, no como un fármaco preventivo del edema pulmonar de gran altitud, sino en la creencia de que podría ayudar a mejorar el rendimiento físico a gran altura geográfica. Varios estudios han tratado de abordar este tema, con resultados contradictorios. Actualmente, a pesar de que no hay datos concluyentes, ni en altitud simulada ni real, y con la clara evidencia de que en normoxia el sildenafilo no mejora el rendimiento físico, se continúa utilizando esta sustancia (a veces en exceso) por personas que suben a altas cumbres. Tal potencial mejora de rendimiento dependería del grado de hipoxemia (altitud) y de la capacidad de respuesta individual a este medicamento. El presente artículo revisa el conocimiento actual sobre este tema.

Section snippets

Mechanism of sildenafil action

Since the work of Ghofrani et al.1 about the improvement of physical capacity during exercise in hypoxia conditions due to the use of sildenafil,1 several studies have attempted to reproduce their findings. However, to date, there is still controversy over whether phosphodiesterase type 5 (PDE-5) inhibitor is a substance that can actually improve performance under hypoxic conditions. Sildenafil has been used to treat erectile dysfunction2 through inhibition of PDE-5 activity which, in turn,

Hypoxia and exercise

Exposure to acute hypoxia (AH) causes the reduction of the maximum aerobic capacity, directly affecting the exercise performance.14, 15, 16 VO2max tends to diminish in direct proportion to the decrease in CaO2, which occurs as hypoxia increases.17, 18 Exercise exacerbates CaO2 reduction due to the lower uptake of O2 during gas exchanging in the lungs,1, 19 which may increase the risk of pulmonary edema,11, 20 especially in people predisposed to suffer this complications associated to rapid

Sildenafil effects during exercise and hypoxia

Research conducted on healthy people, combining the effects of exercise and hypoxia after sildenafil administration, has yielded contrasting results. Studies on this subject present a wide range of designs and methodologies leaving many questions still unanswered about the possible benefits of the sildenafil administration under hypoxic conditions. The following paragraphs present a review of the most relevant studies on sildenafil administration and exercise in hypoxia. All the studies had a

Normobaric versus hypobaric hypoxia

An important point to keep in mind when comparing all the cited reports it is to consider the difference in the hypoxia conditions (simulated or natural) and the type of hypoxia (normobaric or hypobaric) that subjects underwent, because some studies showed differences between exposition to normobaric and hypobaric hypoxia.35, 36, 37, 38, 39 Comparing both types of hypoxia, one study described that hypobaric hypoxia leads to greater hypoxemia, hypocapnia, alkalosis and lower blood SaO2 than

Conclusions

Due that initial research on the effects of sildenafil on pulmonary circulation were conducted in patients with cardiopulmonary disease, it was possible to early confirm that sildenafil is an effective vasodilator of the pulmonary arteries also in healthy people, whether in the hypobaric hypoxia or under normobaric conditions.1, 14, 29, 30

However, it has been ruled out any performance improvement under normoxic conditions after sildenafil administration. Those, the use of sildenafil as an

Conflict of interest

The authors manifest that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed

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