Trail running differs from road running and track running. Trail running generally takes place on hiking trails, most commonly single track trails, although fire roads are not uncommon. A distinguishing characteristic of the trails is that they are often inaccessible by road except at the trail heads. The trails tend to traverse varying terrain; hills, mountains, deserts, forests, and narrow passages are common. Likewise, steep inclines or rough terrain sometimes may require hiking or scrambling. Runners participating in trail runs must often descend these same steep grades. It is not unusual for trail runs to ascend and descend thousands of feet.
There are as many variations of trail running as there are runners. Many individuals prefer running trails for daily training and exercise, while other trail runners spend weeks out in the backcountry. There is a growing number of people participating in solo backcountry trail running trips, which are a sort of ultralight backpacking. While an ordinary backpacking expedition may last for eight days, averaging eight to ten miles per day, with participants carrying fifty to sixty pound backpacks, backcountry trail runner will do the same trip in three to four days, covering much greater distances each day, and carrying only minimal equipment. This type of backpacking is rare, as it is very difficult and dangerous, but it is growing in popularity.
According to a 2010 special report on trail running published by the Outdoor Industry Foundation, "4.8 million Americans ages 6 and older participated in trail running in 2009." This research shows a particularly heavy following in the Mountain States, the Western US, and California.
In the United Kingdom, the British Athletic Federation authorised this definition in 1995:
In the context of athletics, trail races are primarily along footpaths and bridlepaths marked on Ordnance Survey maps as "public rights of way". They are "highways" to which pedestrians have unrestricted access in English law. Towpaths, forest drives, farm cart tracks and paths in parks etc, from which motorised traffic is excluded, are
also trails when the owners' permission is obtained. Some trail races take place in less isolated areas, and routes can include public parks or canal towpaths.
Many trail runners use specially designed shoes that have aggressively knobby soles that are generally more rigid than road running shoes. The usually EVA compound midsole often contain a lightweight, flexible nylon plastic layer to protect the feet from puncture wounds from sharp rocks or other objects. Since trail running take place on softer surfaces (e.g., grass, dirt) than road races, cushioning is not as important so often the shoes are less 'cushioned' than their counterparts designed for tarmac. Additionally, trail running shoes are low to the ground which provides the best stability on uneven terrain.
Other equipment includes wicking garments, water bottles, sunscreen, sunglasses, gaiters, anti-insect spray, and ivy block. Some trail runners attach lightweight crampons to the bottom of their shoes to aid with traction in the snow and on ice. An alternative way to carry water is use a hydration bladder with drinking tube carried in a backpack or waistpack. Everyone should consider carrying the Ten Essentials which may reduce the hazards inherent in wilderness travel. Some trail runners use ultra light hiking poles (which are often not allowed during competition) to increase speed and stability.
Training and events
Trail running takes place in both organized trail races, and as a recreational activity. Trail running is usually an individual sport, although training is commonly done in groups.
Common distances in races are 5 km, 10 km, 20 km, 30 km, marathon (42 km), 50 km, and 50 miles. Anything over Marathon distance is considered an Ultramarathon, and many "ultras" range beyond 100 mile mark. The quintessential North American 100 mile trail run is The Western States Endurance Run, also known as the Western States 100. In Europe, the UTMB, won by the young Kilian Jornet Burgada is gathering more than 4000 participants who compete on the legendary 160K trail touring around the Mont Blanc mountain. Another similar running event is held on an annual basis in Odessa, Ukraine in the closest Saturday to 10 April, celebrated as the Liberation Day from Nazi Germans in the World War II, 100 km in distance, around the city's defense lines at World War II.
Trail Running Series & Challenges
There are also many Trail Running Series that combine multiple races over the course of the season. The most popular of these include the Grand Tree, which had 2100 participants in 2009, Grand Tree Trail Races the Rock/Creek Trail Series, which had 1900 racers and volunteers in 2009, and the Montrail Ultra Cup, which includes 11 races in the 2010 series.
The Kokoda Challenge Race is an annual 96 km endurance race held in late August that runs the length of the historic Kokoda Track in Papua New Guinea.Kokoda Challenge In Great Britain, the new "Lakeland Trails" is the biggest trail running series with over 3000 competitors in 2006. In South Africa, there is 3 day, 112 km wilderness stage race along the beautiful 'Wild Coast' region called the "Wildcoast Wildrun"."Wildcoast Wildrun" Another popular 3 day event in the Kleinmond wilderness is the "African-X". One of the toughest and most prestigious of all the Trail Runs in the country is the Marathon Distance Otter-African Trail Run""Otter-African Trail Run" which follows the entire distance of the famous 5 day Otter Trail. Another annual event is the 80 km Peninsula Ultra Fun Run or "PUFfeR","PUFFER" from Cape Point to Cape Town's waterfront district via the summit of Table Mountain. A variant of this trail run is the "Tuffer Puffer""Tuffer Puffer" starting at the usual finish and doubling the distance. By far the biggest and most popular trail running race series in South Africa is the "Trail Series" with 20 races per year and over 4100 unique participants. The Rhodes Trail Run and Skyrun are two events staged in the southern Drakensberg mountains.
Multiday Trail Races
The longest Trail race on the South African trail running calendar since 2000 is the Kalahari Augrabies Extreme Marathon - a 7-day, 250 km self-sufficient run through the Kalahari Desert. The South African trail calendar is available on the internet."Wildrunner" A new class of fully-supported trail running stage races has also emerged in recent years, such as the GORE-TEX Transalpine Run in Europe (8-days, 250 km) and the GORE-TEX TransRockies Run in Colorado, USA (6-days, 106 miles). These multiday stage races offer complete support and runner amenities between stages.
Trail races differ considerably from other races, since runners enjoy the solitude of nature for the bulk of these runs. In addition due to the smaller number of participants, the odds of running with no other participants in sight are very good. Similarly, runners in these events must rely on their own inner resolve, since crowd support is very limited given the inaccessibility of the courses. Trail races are commonly equipped with aid stations supplying food and beverages every 5 to 10 kilometers. Nevertheless, runners in trail races, particularly longer ones, usually carry their own water and food along the course.
During training runs, carrying one's own beverages is a necessity. Additionally, navigational skills are much more important during training runs, where one invents the course oneself, compared to organized races where the courses are very well marked (this is a matter of interpretation). Carrying maps when training in unfamiliar areas is highly recommended, as runners cover large distances and veering off course is not uncommon, especially in areas where signage is limited.