Should I start my horse under saddle in large circles at least 60 feet in diameter?

Yes — and the reasoning behind this recommendation is rooted in biomechanics, horse psychology, and training principles that together make large circles not just preferable but genuinely important for the physical and mental wellbeing of horses in the early stages of under-saddle work. The instinct to work young horses in small tight circles out of a belief that the contained space gives the rider more control is one of the most consistently harmful habits in early horse starting. The physical dimension is the most immediately important. A young horse being started under saddle is typically two to three years old, and skeletal and soft tissue development at that age is not yet complete. Growth plates in the long bones are still open, joint cartilage is still developing, and tendons and ligaments are still building their strength. A small circle — anything under fifteen meters — creates asymmetrical mechanical loading that a developing horse's body is not yet equipped to manage without risk. On a small circle the inside hind leg must flex more deeply, adduct more strongly, and carry more weight per stride, and that asymmetrical demand applied repeatedly through a training session on a horse whose joints and soft tissue are still developing creates cumulative stress that can produce soreness, joint irritation, and in more severe cases the early stages of pathology that appears as hock problems, stifle issues, and soft tissue damage in horses worked too small too young. A sixty-foot diameter circle — approximately eighteen to nineteen meters — is near the minimum appropriate size for early under-saddle work, and larger is generally better. An even larger circle is appropriate when the horse is particularly young, particularly tight through his body, or particularly unbalanced, because the larger arc makes fewer physical demands on the inside joints and allows the horse to find his balance and rhythm with less mechanical stress. The psychological dimension matters nearly as much. Young horses managing an entirely new potentially anxiety-provoking experience do not become calmer on small tight circles — they become tenser and more reactive because the small circle amplifies physical discomfort and psychological confinement simultaneously. A large circle gives the young horse room to move forward freely, find his balance naturally, and experience the under-saddle work as a manageable non-threatening demand. The transition to smaller circles happens naturally and progressively as the horse develops the physical strength, suppleness, and balance to manage the increased demands that smaller arcs create. The trainer who decreases the circle size when the horse's development genuinely supports it produces a horse whose gymnastic progression is sustainable rather than forced.