Roberto Firmino alarmed Liverpool supporters on social media after sharing an image of him wearing an oxygen mask.
The Brazil international is continuing his recovery from the 'serious' hamstring injury sustained in the Reds' 2-0 Champions League win over Atletico Madrid.
Firmino missed Liverpool's last Premier League outing versus West Ham United and his exact return date is unknown.
And the 30-year-old raised fears that he could be missing for an extended period of time after posting a video that showed him lying down with an oxygen mask attached to his face.
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Harvey Elliott shared a similar post with fans last month while recovering from his ankle injury, which also led to questions from fans.
To provide insight into why Elliott could be using an oxygen mask, the ECHO spoke to Dr. Rajpal Brar, a physiotherapist and founder of 3CB Performance, providing expert analysis on injuries suffered by sport stars.
His informative comments on Elliott can also be applied to Firmino's current situation.
"The mask and tube are likely hooked up to a portable oxygen concentrator and pumping oxygen through to Elliott’s system," Dr Brar explained.
"This is known as “oxygen therapy” and the theoretical rationale is that because oxygen is critical for healing then pushing more oxygen into the lungs and thus into the bloodstream and tissues may increase rates of healing (the research is very mixed).
"To that point, he is using an oxygen face mask which allows for greater concentration and rates of oxygen flow compared to a nasal cannula (small tube) directly into the nose.
"Face masks also tend to be more comfortable because they deliver air that’s more moist which doesn't dry out the nasal passages, there’s nothing physically touching the nose, and some masks - as Elliott’s - also have options to insert the hose near the nose or the mouth."
