Grunewald has accompanied her husband on some of his training runs during her cancer battle

"Thank you for showing me what bravery looks like."

That message of appreciation was sent by American marathon runner Kara Goucher last Sunday to her compatriot and fellow distance runner Gabriele Grunewald, whose death was announced on Wednesday.

Britain's world marathon record-holder Paula Radcliffe also tweeted Grunewald, thanking her for the lives she has "enriched by courage and love".

The emotional messages came as Grunewald, who is 32, was moved to end-of-life care following a 10-year battle with cancer.

Her husband asked people to post her "one last message", external-link prompting a flurry of activity on the #bravelikegabe hashtag.

A US champion against the odds

Grunewald was the US champion over 3,000m indoors as recently as 2014 and her 1500m personal best of four minutes 01.48 seconds a year earlier remains the 12th fastest set by an American woman at that distance in history.

She continued to train and race throughout a cancer fight that saw her have several treatments to rid her of the illness, including having half of her liver removed in 2016.

After having radiotherapy for a second cancer treatment in 2011, she even finished fourth in the US 1500m trials for the 2012 London Olympics, missing out on a place by one position.

Grunewald thought she was cancer free in 2016 but scans within two years showed she needed further treatment.

Her husband Justin, a doctor, has documented her fight online and revealed when he told her she was close to death a week ago, she yelled "not today" in reply.

A husband's letter to his best friend

In asking for one more message from followers before his wife "heads up to heaven", Grunewald also shared a letter he gave her two years earlier.

It read: "Thank you so much for showing me what it's like to be and feel alive. It's easy to pass through life day to day and punch a time card wishing away the hours.

"Currently although I don't always show it, I cherish every second. Whether we are out running, binging on a new Netflix series, or just lying in bed being lazy. Nothing beats the feeling I get when I see your smiling face.

"I know life is scary and I know we have won the lottery of uncertainty, and it's not fair, but I still choose our life of uncertainly and at times fear, over any alternative option I could think of. I have so much fun with you and have learned more from having you as my best friend and wife than I learned in the rest of my life combined.

"I know you have been given the heaviest of tasks in life. The task of being brave despite feeling enormous amounts of fear. The task of smiling when your throat wells up with pain and eyes want to fill with tears, but I don't think you were chosen by random chance, and again I know that's not fair but you are so amazing at being you and that's why I feel bravelikegabe is so special. Because there isn't a word in the dictionary for what you do or who you are. Brave flails in comparison to what you are to me and to so many people out there facing the simplest and silliest of struggles in day to day life.

"At the end of the day people won't remember the PRs run or the teams qualified for but they will remember that hard period in their life where they were losing hope but they found inspiration in a young lady who refuses to give up.

"I love you."

Courage, love, admiration - messages for Gabriele

Gabriele's husband Justin shared an emotional letter he sent to her

Marathon world-record holder Paula Radcliffe: The bravery, heart and smile of @gg_runs will always shine brightly and inspire so many. Thinking of you and of @JustinGrunewald and all those whose lives were enriched by your courage and love.

World, European and Commonwealth medallist Jo Pavey: Gabriele Grunewald has inspired so many people with her bravery and courage. Every time I read about Gabriele I am moved and full of so much admiration for her.

American long-distance runner Kara Goucher: I love you so much @gg_runs! Thank you for showing me what bravery looks like. Always love your way.

Deena Kastor, 2006 London Marathon winner: Dear @gg_runs, Wishing you peace and the wings you so deserve. @JustinGrunewald, Thousands of people are grateful for your own courage and are sending you love. Feel it overflowing in your big, big heart.