On Saturday 1st to Friday 7th August 2026 an international group of young people who live with the rare condition, McArdle’s disease will gather in the National Trust Outdoor Learning Centre at Stackpole, Pembrokeshire.
The UK McArdle’s walking courses officially called “The McArdle’s Experience” aim is to teach people with this rare muscle condition how to manage their symptoms safely through structured aerobic exercise.
Organised by the AGSD-UK, these residential events allow participants to safely build fitness, learn pacing techniques, and connect with a supportive community. The international event is in its sixteenth year with its location each time rotated among the three National Parks of Wales.
McArdle’s disease (Glycogen Storage Disease Type 5) is a rare genetic condition where the body cannot properly break down muscle glycogen for energy. In young people, it typically manifests as severe exercise intolerance, causing early muscle fatigue, cramping, and pain during the first minutes and throughout all intense activity.
Among those joining the course this year is the Vistoli family from Kitchener, Ontario, Canada, with their son Everett, age 7. His mum Kendra said;
“We knew something wasn’t right when Everett was an infant, he had difficulty with learning to walk, a delayed, waddling gait, frequent falls and sometimes used his hands to climb up his legs to stand. We took him to a paediatrician as we were concerned about the possibility of muscular dystrophy.
“Everett was eventually referred to a neuromuscular specialist where testing continued. During this time, Everett had EMG, genetic testing, and muscle biopsy done – his muscle biopsy showed an accumulation of glycogen, he was finally diagnosed with GSD9d, which is closely related to GSD5, just before he turned 4 years old.”
Daily life for the Vistoli family is heavily impacted; activities take longer and require more patience and planning. Kendra went on to say;
“Everett also struggles with ADHD, and he tends to want to go-go-go but then ends up in a boom-bust cycle of crashing and being in pain and struggling to do physical activity. We always have to be mindful of how his body is feeling and what he is capable of each day avoiding activities where we might get “stuck” if he can’t continue, if we don’t have a plan to support him if he’s out of energy or in too much pain to continue.”
Andrew Wakelin is AGSD-UK’s McArdle’s coordinator who devised the walking courses, after he was diagnosed with the disease . Andrew said;
“We are excited to welcome Everett as the first person with GSD9d to visit our course. We think there may be only about 50 people worldwide diagnosed with GSD9d, so this is a very special occasion.
“We host a course for young people and an adult’s course, each with their own programme of learning and walks. Teaching young people to recognise their body’s warning signs and to exercise at their own pace is vital for preventing muscle damage and maintaining an active lifestyle.
“We aim to share all the techniques that make the day-to-day management of McArdle’s easier. There are walks to put learning into practice, to boost confidence and aerobic capacity. The aim is making walking safe and enjoyable, and the bonus is that this is done in a holiday atmosphere, with a friendly and understanding group and in a beautiful location.”
Kendra went on to say;
“I think having the opportunity to meet others who have a similar condition and experience is invaluable. Connecting and learning from those who have the wisdom and experience to share what helps them most is truly a gift.
“Everett loves the outdoors and hiking. I think he is excited about the challenge of hiking a mountain. I’m not sure how much understanding he has about his condition and how to manage it, so I’m very much looking forward to him having the opportunity to learn from others who have lived experience and who truly understand it.”
Chief Executive of AGSD-UK, Val Buxton said;
“For people affected by glycogen storage disease, living with such a rare and little understood condition can be incredibly challenging. That’s why events like the McArdle’s walking courses are so important.
“They are a valuable opportunity for those affected to come together with others who can relate to their experiences. Community members have described the connections they’ve made, and insights gained at these events as life changing. We’re so grateful to everyone who supports AGSD-UK’s vital work on their behalf.”
Feature image: Everett Vistoli (bottom left) and his family
