The sound of a starting gun can cause a runner with PTSD to "fall into a panic, or complete despair," a Ukrainian war veteran told AFP -- but help is at hand due to a revolutionary system devised in Ukraine.

The organizers of the Nova Post Barrier-Free Marathon in Kyiv on September 15, which attracted 5,000 runners from 40 countries featuring races over several distances, introduced the Start Without a Shot system after consultations with experts around the world.

Start Without a Shot uses digital sound and also a hand-held arrow-shaped object that changes color from red to green when the starting signal sounds.

It has received a positive reception from war veterans and psychologists who treated post-traumatic stress disorder (PTSD) sufferers following the 2013 Boston Marathon bombing which killed three and injured hundreds.

"We conducted research to compare the impact of a starting gunshot with the newly created sound," Elena Plakhova, Reputation Management Director at Nova Post, told AFP.

"The increase in stress levels recorded for the gunshot sound was almost seven times higher than for the new signal."

Plakhova, whose company has been organizing running events since 2015, can empathise with those suffering from PTSD.

"I myself was in Donetsk in 2014 (when Russian-backed separatists seized territory in the Donbas region) and experienced all the most painful stories one could endure," she said.

"I remember once visiting my mother in the then-peaceful city of Mykolaiv, and I heard the sound of a motorcycle.

"That sound made me drop to the floor and cover my head because it triggered very negative associations."

Plakhova says her company are "engaging" with marathon organizers in Europe and America "to introduce and demonstrate" the starting signal.

If they need any convincing it is effective then look no further than Dmytro Kerbyt, who was seriously wounded serving on the frontline with the Ukrainian army.

The 42-year-old was hit by shrapnel after the Russians fired an RPG at him and his comrades.

"My nose was completely torn off, and nearly all my upper teeth were knocked out," he said. "My lower jaw was also fractured.

"But I opened my eyes and although I saw my teeth were scattered on the bottom of the pit, I was oddly happy about this because it meant my eyes were intact."

'An important beginning'

Kerbyt, an ultra marathoner who has taken part in an Iron Man competition since undergoing plastic surgery, says replacing the starting gun opens up a host of opportunities for PTSD sufferers.

"The sound of a regular gunshot is very reminiscent of the sound of a combat pistol, bringing back memories of the place from which the soldiers returned with injuries," he told AFP.

"Even those who went on leave and wanted to go to a sporting event, can't do that because of the sound of the gunshot.

"That's why replacing it with such a sound signal, along with a visual indicator, is a very good solution."

Kerbyt said it meant a lot to veterans that their compatriots were thinking how to smooth their adaptation back into civilian life.

"Veterans are being thought of, veterans are being remembered. Even through small but meaningful innovations."

Psychologists Holly Aldrich and Janet Yassen, who are based at Harvard Medical School, have decades of experience working with those impacted by gun violence, including survivors of the Boston bombing.

Both welcome the invention, with Aldrich appreciating its inclusiveness.

"Victims/survivors are often 'othered' by those around them... distanced in a way that reinforces apartness and isolation," she told AFP.

"A marathon is many things for many people. But at a minimum, it's a diverse gathering of people who've chosen to be present.

"And this is introducing a change that can raise awareness, that transcends divisiveness.

"It's an important beginning."

Some may quibble over how big a deal this is and point to more effective methods of improving the lives of those with PTSD.

However, Kerbyt says the benefits for him and his fellow veterans of pounding the roads and pavements cannot be underestimated.

"Running definitely gives that bright moment, that everything will get better, that everything will be as it was," he said.