England boss Thomas Tuchel saw the lighter side when questioned on whether his Three Lions' stars have been using Viagra to combat the altitude of Mexico City.

Their World Cup last-16 tie with co-hosts Mexico will take place at the Azteca Stadium, which is 2,200 m (7,220 feet) above sea level. 

The altitude has been viewed as a major advantage for Mexico, who have a record of 70 wins, 17 draws and just two defeats at the stadium in 89 matches.

Tuchel had conceded that England would not be able to 'physically adapt to it' in time for the match.

The question was posed at Tuchel's pre-match press conference whether England had turned to Viagra to help them to adjust.

Viagra, the brand name for Sildenafil, is best known for being used to treat erectile dysfunction. 

Viagra has previously been reported to improve exercise performance at high altitude, due to relaxing pulmonary vessels.

In turn this would reduce pulmonary arterial pressure, increase cardiac output, improve gas exchange, and allow for enhanced oxygen delivery during exercise.

'Is it true you have been using Viagra to mitigate effects of the altitude, that is information that came along, is that really true,' Tuchel was asked.

'The information and the support did not reach me,' Tuchel responded smiling.

'That is not true.'

Jordan Henderson also saw the funny side when asked about how the England squad were taking the particular challenge of playing Mexico at altitude.

'Well the Viagra helps,' Henderson quipped in response, before adding 'I'm joking'.

It is unclear whether Viagra would have any impact had England players taken it to help performance at altitude.

A World Anti-Doping Agency project previously examined the impact of Viagra in helping athletes at altitude, after performance was found to have been improved in over 35 per cent of athletes when above 3,800m.

The project examined whether the same impact was had at lower altitudes, with two studies conducted.

'The efficacy of sildenafil during exercise at altitude is integrally related to its ability to improve oxygen delivery by increasing SaO2 (Arterial Oxygen Saturation) and/or cardiac output,' the project concluded.

'The magnitude of these effects appears to be dictated by the severity of the altitude and associated hypoxia as well as individual susceptibility to hypoxic pulmonary vasoconstriction. 

'Sildenafil is unlikely to exert beneficial effects in oxygen delivery or exercise performance at altitudes < 4000 m for the vast majority of the endurance trained men or women.'

England boss Tuchel admitted that his squad could feel the impact of the altitude in the build-up to the last-16 match.

‘You know what, we feel it,’ Tuchel said on the eve of the last-16 clash following his side’s first and final training session at altitude. 

‘We feel it, even if we don't train. I felt a slight headache and in the hotel room through the day, didn't sleep as well as the days before.

‘It’s nothing that you cannot handle and cannot adapt (to), the players felt it in the first minutes of the training session and the longer it went they could cope with it better.'

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