A pacer is a runner who accompanies an ultramarathon competitor for part of a race — typically the later, harder stages — to provide company, motivation, navigation help, safety, and practical support. Pacers run alongside the racer but, under most race rules, cannot physically aid them (no carrying gear or 'muling' where prohibited). Pacing is common in long trail ultras, especially overnight, and is distinct from a crew.
A crew is a support team — friends, family, or helpers — who assist an ultramarathon runner during a race by meeting them at designated aid stations or access points to provide food, drinks, fresh gear, dry clothes, first aid, and encouragement. Unlike a pacer (who runs with the racer), the crew supports from the sidelines, helping the runner resupply and care for themselves quickly so they can keep moving. A good crew can be a major asset in a long race.
A drop bag is a bag of supplies a runner packs in advance and the race transports to a specific aid station, so the runner can access their own food, gear, clothing, and other items partway through a race — especially in ultramarathons. Drop bags let runners resupply with personalized items at points along the course where they can't have a crew, making them a key logistical and strategic tool in long races.
An aid station is a checkpoint along a race course — especially in trail races and ultramarathons — where runners can refuel and resupply with water, electrolytes, food, and sometimes medical help, drop bags, and access to crew. Aid stations are crucial lifelines in long races, and using them efficiently (refueling fast without lingering too long) is an important racing skill. They also serve as cutoff checkpoints and safety points.
A technical trail is one with rough, uneven, and obstacle-filled terrain — rocks, roots, loose scree, steep drops, stream crossings, and tricky footing — that demands careful foot placement, balance, and agility rather than allowing a steady, automatic stride. Technical terrain slows pace, raises the risk of trips and falls, and rewards skill and attention, making 'technicality' a key way runners and hikers describe a trail's difficulty beyond just distance and elevation.
A vertical kilometer (VK) is a mountain running race in which competitors climb 1,000 meters (about 3,280 feet) of vertical elevation gain, typically over a short course of around 5 kilometers or less — making it extremely steep. An uphill-only race that tests pure climbing power and lung capacity, the VK is a recognized discipline in mountain and skyrunning, where steepness is so severe that even elite athletes power hike much of the course.
Vert is slang for 'vertical gain' — the total amount of elevation a route climbs, measured in feet or meters. A key measure of a route's difficulty alongside distance, vert captures how much climbing is involved, which dramatically affects effort, time, and fatigue. Trail runners and hikers track vert to gauge and compare routes, plan training, and describe how mountainous an outing is ('lots of vert' means a lot of climbing).
An FKT (Fastest Known Time) is the fastest documented time for traveling a specific established route or trail, set outside of an organized race. A grassroots alternative to racing, FKTs can be attempted on any well-defined route and are categorized by support style — supported, self-supported, or unsupported. They rely on honesty, documentation (GPS tracks), and a community ethic, and have surged in popularity in trail running.
Ultrarunning (ultramarathon running) is the sport of running races longer than the standard marathon distance of 26.2 miles (42.2 km). Common ultra distances include 50K, 50 miles, 100K, and 100 miles, as well as timed events. Most ultras take place on trails and mountains, emphasizing endurance, fueling, hiking the climbs, and mental resilience over raw speed, with aid stations and sometimes crew and pacers supporting runners.
Trail running is the sport of running on natural, off-road terrain — trails, mountains, forests, and deserts — rather than pavement. It blends running with the variability and challenge of the outdoors: uneven footing, elevation change, and remote settings. Compared with road running, it emphasizes effort over pace, demands more technical skill and gear, and rewards runners with scenery and lower-impact surfaces.
