Rethinking the "Twelve Stone" Rule for Native Ponies
- Ally Lowther
- 6 hours ago
- 6 min read
At this year’s Horses Inside Out Conference: Soundness and Symmetry, a veterinary chiropractor from Cornwall won the scientific poster competition. The questions she raised are ones every native pony owner should be asking.
About the competition
The Horses Inside Out Scientific Poster Competition is one of the highlights of the annual conference, giving researchers, practitioners and students the opportunity to share original work other like-minded equestrian professionals. This year’s competition saw an impressive field of entries and the standard of research on display was exceptional.
Jenna Payne MSc was crowned the 2026 Winner with her poster entitled - "A preliminary investigation into the effect of rider weight and pony age on the mechanical nociceptive thresholds (MNTs) of the epaxial muscles and heart rate variability (HRV) of Exmoor ponies", the first study of its kind on a British native breed, and the first conducted in a hacking environment.
Meet The Winner
Jenna Payne is a McTimoney Veterinary Chiropractor based in Cornwall with an enormous passion for British native breeds — in particular Welsh Cobs and Exmoor ponies. She also works in the agricultural show industry, giving her an unusually broad perspective on the animals she studies and cares for. She carried out this research as part of completing her Masters' degree at the McTimoney College of Chiropractic.
What Jenna Set Out to Discover
The starting point was a question many native pony owners will recognise. The Exmoor Pony Society advises that the breed “can carry up to twelve stone” — but Jenna found herself wondering whether that guideline truly reflected the welfare of the animals it was meant to protect. “Although I fell well within that guideline,” she explains, “I found myself wondering whether that limit truly reflected the welfare of the ponies I bred and rode.”
That personal unease became the seed of something significant. With the support of her course leader Nikki Routledge, Jenna designed what would become the first study ever to investigate the impact of rider weight on a British native breed, and the first to assess this in a hacking, rather than competition environment. This distinction was important because the vast majority of native ponies are used for leisure riding rather than competition.
“So many native ponies are used for leisure riding rather than competition. This matters — and yet no one had studied it.” Jenna Payne
How The Study Worked
The project took over a year to bring to life, though the data collection was carried out over three consecutive days at the Exmoor Pony Centre in Dulverton. Trekking centre manager Linzi Green played a crucial role, providing access to an exceptionally uniform group of ten trekking Exmoor ponies, ranging in age from 13 to 25 years, which allowed the team to gather meaningful, comparable data.
PONIES 10 Exmoor trekking ponies, aged 13–25 years | ROUTE 4.28 km at walk & trot, once per day | RIDER WEIGHTS Lightweight, middleweight and heavyweight (as % of pony bodyweight) | MEASUREMENTS MNTs & HRV before, immediately after, and 2 hours post-ride |
Each pony completed the same 4.28 km trekking route at walk and trot with three different riders — classified as lightweight (9.7–12.7% of pony bodyweight), middleweight (13.9–17.6%), and heavyweight (18.7–23.1%) — in a randomised crossover design. The team measured mechanical nociceptive thresholds (MNTs) — in essence, the muscles’ sensitivity to pressure and pain at multiple points along the spine, before riding, immediately afterwards, and again after a two-hour rest. Heart rate variability (HRV), a physiological marker of stress, was also recorded.
What The Findings Reveal
The results are striking and challenge assumptions that have shaped native pony management for generations.
Immediately after riding
Epaxial muscle sensitivity increased significantly across all rider weights — particularly in the mid-thoracic and lumborum regions. The effect was most pronounced in older ponies (18+ years), whose muscles showed increased sensitivity regardless of rider weight, while younger ponies were most affected by heavier riders.
After a two-hour rest
Muscle sensitivity had not fully recovered. MNTs remained significantly lower than pre-ride levels across all rider weights, with the mid-thoracic and sacral areas most affected — suggesting the muscles had not returned to baseline even after rest.
Heart rate variability (stress)
Two hours after riding, neither rider weight nor pony age had a significant effect on HRV. Physiological signs of stress were not apparent.
Age matters
Older ponies (18+ years) were sensitive to all rider weights. Younger ponies (17 and under) showed significant muscle sensitivity primarily in response to the heavier rider — underlining the importance of age as a welfare consideration.
The absence of measurable physiological stress — as indicated by HRV is a fascinating counterpoint to the muscle sensitivity findings. Jenna poses the question that will resonate with anyone who has spent time with Exmoors - is this stoicism a reflection of the breed’s legendary hardiness, or does it mask discomfort that owners might otherwise miss? It's a question she hopes future research will explore.
“Exmoor ponies may not be the weight-carriers many believe them to be. They do feel the impact of rider weight — and that should start a conversation.” Jenna Payne
Why This Matters for Welfare
The implications reach well beyond the Exmoor breed. Current rider weight guidelines for native ponies are widely accepted but rarely scrutinised — and they are almost always based on competition settings rather than the realities of everyday leisure riding. This study is the first to place that question in a hacking context, with ponies doing what the majority of native breeds actually do.
The finding that older ponies are particularly sensitive to rider weight should prompt every owner of a veteran native pony to reflect on the loads they are asking their animals to carry. And the fact that these ponies did not show outward signs of physiological stress makes the case for using objective assessment tools — like MNT measurement — to detect what we might otherwise miss.
What Comes Next?
Jenna credits Sally Charlton with encouraging her to bring the research to the Horses Inside Out Conference. “Her guidance sharpened the clarity of the research,” Jenna says, “and I owe her as much credit for the recognition it has received.” Being selected to present was, in Jenna’s own words, already an honour. Winning the award was something she “never imagined” and she remains “genuinely humbled” by it.
For Jenna, the prize matters far less than what the research might set in motion. She hopes her work sparks more conversation, and crucially, more studies about how we can best support the welfare of Britain’s native breeds. calling for future work with larger cohorts, different breed types, and investigation into the longer-term effects of rider weight on epaxial muscles.
We extend our warmest congratulations to Jenna, and our thanks to the entire research team — Nikki Routledge, Sally Charlton, and Adrian Hunnisett — and to Linzi Green at the Exmoor Pony Centre for making this study possible. Our thanks also go to all who entered and presented at this year’s competition. The standard of science continues to rise, and that reflects the commitment of this community to evidence-based equine welfare.
Read the full poster
Jenna’s scientific poster — including full methodology, statistical analysis and data charts is available to view here.
Could you create a scientific poster on the theme of Wellness and Welfare for the Horses Inside Out Conference 2027? Whether you have research, case studies, or practical observations to share, why not submit them as a poster?
Presenting a scientific poster at a conference is an exciting and worthwhile thing to do, but you may have previously ruled this out feeling that your experience or the data you have isn't suitable for a scientific poster. Think again! Information collected in the field can be a highly valuable resource and if analysed correctly can help inform future practice.
Still not sure where to start? Don't worry, we're here to help get you started. Mastering Scientific Posters for Wellness and Welfare is a FREE webinar with Professor Meriel Moore-Colyer. Join us at 6.30pm (BST) on Monday 1st June 2026 and Meriel will walk you through the process, share topic ideas, and show you exactly how to create a compelling poster.
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