They're related but they don't do the same job. A martingale, running or standing, mostly limits how high a horse can throw its head, working passively until the horse pushes against it. A training fork attaches from the girth or breast collar up to the bit or reins and takes a more active role in shaping headset and poll flexion while you're riding.

• Martingale: Anchors at the girth and neck strap, restrains upward head movement, doesn't do much until the horse tests it.
• Training fork: Runs girth to bit or reins, actively encourages a rounder, lower carriage during work.
• German martingale: A hybrid using rope through the bit rings, adjusts with rein pressure so it teaches rather than just blocks.

No, not when they're sized and adjusted correctly and paired with a rider who isn't riding off the martingale instead of their hands. Problems show up almost exclusively from a fork or martingale set too short, forcing a headset instead of encouraging one, or from leaving it on a horse that hasn't been taught what the pressure means yet.

• Correct fit: The horse can still flex, chew the bit, and move its head naturally at a walk with light rein contact.
• Too tight: Constant downward pressure even when the horse is relaxed and standing still is a sign to loosen it.
• Training tool, not a fix: A fork can support correct headset work, but it won't build topline strength or teach flexion on its own.

Yes, several forks and German martingales in this style are built specifically with roper and barrel horses in mind. The Weaver harness leather rubber tube fork and the roper-style German martingales, for example, are made to hold up to fast starts and stops while still teaching a horse to travel with its head down and flexed at the poll instead of hollow and above the bit.

• Rubber tube forks: Add a bit of give so a hard stop doesn't create a sharp correction at the poll.
• Roper German martingales: Use rope through the bit rings with dees on the reins, adjustable enough for pattern work.
• Harness leather builds: Hold up better to arena dust and repeated cinching than lighter latigo in high-use disciplines.

You'll know it's right when the horse can carry its head in a natural, relaxed position at a standstill and only feels contact when it tries to raise its head past where you want it. A fork that's too short creates constant downward pull, and one that's too long does almost nothing at all.

• At rest: No tension in the fork or martingale straps when the horse's head is in a neutral position.
• Girth adjustment: Most forks adjust in a range, for example 24 inches to 30 inches on shorter styles or up to 43-52 inches on longer training fork and girth attachment combinations, so length should match the individual horse, not a one-size guess.
• Hardware check: Rings and snaps, usually 1-3/4 inch on harness leather styles, should sit flat against the chest without pinching or twisting.

A running martingale splits into two straps that the reins pass through, applying leverage only when the horse raises its head above the rider's hand. A German martingale instead uses a length of rope, often 1/4 inch nylon, that runs through the bit rings and snaps onto adjustable dees positioned along the reins, letting the rider fine-tune exactly how much headset pressure is applied.

• Running martingale: Rein-dependent leverage, simpler design, common on trail and all-around horses.
• German martingale: Rope-through-bit-ring design with adjustable dee positions, popular with reining and roping trainers working on collection.
• Shared goal: Both promote flexion at the poll, they just get there through different mechanics.

It really comes down to how the horse is used and how much upkeep you want to do. Harness and latigo leather, especially oiled or russet varieties, offer more classic looks and mold to the horse over time, while nylon martingales shrug off moisture and mud with almost no conditioning required.