Early last year Callum O’Dwyer would often lace up his running shoes and prepare to head out on another training run.

His plan was to properly nail 10k, before shifting up to a half-marathon. Then, despite admitting that he is “not necessarily an athletic person”, perhaps even up to a half or full triathlon.

“I was swimming, cycling, going to the gym,” he recalls. “I was 28-years-old, I led a very active lifestyle, I was employed full-time as a mechanical engineer in the oil and gas industry. It was pretty demanding, but I was enjoying the challenges.”

Life was good: he had his own home in Aberdeen, weekends were often spent in Edinburgh visiting his girlfriend, seeing friends, pursuing hobbies.

Now, 15 months after he first fell ill with Covid-19 within hours of the first nationwide lockdown and struggling with the impact of long Covid, he is still struggling to get back to the life he once had.

“At 29 years old, I now couldn’t live without personal care of some description – there are too many things I can’t do by myself,” he says.

“It has been life-changing. I went from someone able to confidently live life as I wanted to, to having a very restrictive lifestyle. I feel disabled, and completely changed.

“The virus has changed my life.”

Callum is now calling for specialist centres to be established in Scotland to help care for the complex medical and mental health needs of people like him who are struggling with long Covid.

NHS England has provided £10 million for a network of long covid clinics which bring together doctors, nurses, physiotherapists and occupational therapists to offer physical and psychological assessments and refer patients to the right treatment and rehabilitation services.

The clinics were launched in November, and there are now 69 operating across the country.

But while the Scottish Government has funded a range of research projects into long Covid, it has not opted against establishing specialist clinics.

The First Minister has said there is “not sufficient understanding” of the condition to know what specialisms are needed to properly treat sufferers.

Instead, Scotland’s estimated 87,000 long Covid patients have been told to use GP services, who will refer them to specialists as appropriate. That, however, has led to concerns over pressure on GPs.

Callum will tell of his 15-months battle with the virus in new episodes of the BBC ALBA programme, Trusadh: Sgeulachdan a’ Ghlasaidh (Life in Lockdown). In it, he recalls how he was so weak, he struggled to lift a water bottle or to use his phone to text.

He now says he fears Scotland is being left behind in the care of people with long Covid.

“This is a brand new condition,” he adds. “We are more than 12 months behind England.

“Primary care has to be a key component of treatment, but if we were referred by our GP to a specialist centre for long Covid, where research can be disseminated to a small group of people faster and where lots of people are being seen regularly by nurses and doctors it would develop the best clinical practice.

“Doctors would be seeing people in a concentrated way.”

Callum became ill on the first day of lockdown in March 2020, with chills, a cough, weakness and breathlessness. His condition improved slightly after two weeks, but then deteriorated.

While most people affected by Covid-19 make a full recovery after 12 weeks, some experience lingering and debilitating symptoms, including tiredness, muscle aches, fatigue, difficulty sleeping and chest pains.

Earlier this week researchers at Imperial College London said a new study showed almost 40% of people with Covid-19 experience persistent symptoms for 12 weeks or more, and warned a “small minority” may struggle with health issues related to the disease for years.

Sufferers have included former Countdown presenter Carol Vorderman who says long Covid left her unable to walk further than 100 yards for months. There have also been reports of sufferers being driven to take their own lives, while the UK’s longest-known Covid in-patient Jason Kelk, died last week after fighting the infection for 14 months.

Callum says he was so fatigued that basic tasks like cooking were exhausting, and heart palpitations that “felt like someone slammed a door on my chest”. He also suffered stomach pain, digestion problems and ‘brain fog’ that left him unable to think straight.

He now wonders if not receiving hospital care and oxygen during his initial bout of Covid-19 may have sparked the lingering symptoms.

“I was gasping for breath and scared. Everyone was being as helpful as possible, but the second I got through to a nurse or doctor they said they wouldn’t be bringing me in to be seen. I wish now I had had oxygen - maybe some would have been beneficial.”

His vaccination in March, however, has brought hope: he believes it may have kickstarted his immune system and improved his symptoms.

“I still have to pace myself, but I can now walk the dog,” he adds. “I feel I’m in a new phase and it’s a joy to be able to live, even the way I do.”

Episodes five and six of Life in Lockdown, produced by Stornoway-based MacTV, include contributions from a newly qualified doctor working on a Covid ward, a family of five on the Isle of Lewis whose lives were impacted by the virus, and a primary school teacher in Glasgow juggling work and caring for her toddler.

Trusadh: Sgeulachdan a’ Ghlasaidh (Life in Lockdown) is on BBC ALBA on Wednesday, June 30 and July 7 at 8.30pm