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How to choose a trail running jacket

For a trail runner, every piece of equipment matters. First and foremost, there's the pair of shoes, but the jacket also holds a crucial place. A true barrier against the elements, it must offer protection, comfort, and adaptability to often changing and sometimes extreme weather conditions. Whether you are running on wind-swept mountain trails or through wet and rainy forests, choosing the right trail running jacket can drastically improve your experience and performance. This guide will walk you through the essential criteria for selecting a jacket that not only meets your specific needs but also allows you to face nature with confidence while being safe.

Understanding the Specifications of a Trail Running Jacket

Trail running jackets stand out significantly from running jackets or other sports jackets due to their highly specialised design. Crafted to meet the challenges of varied terrain, from steep climbs to fast descents and often unpredictable weather conditions, offering superior protection against the elements. Trail running jackets incorporate advanced technologies that enhance waterproofness and breathability while effectively protecting from the wind. These jackets are also designed to be lightweight and compact, allowing runners to carry them without extra bulk. Unlike classic running jackets, which may be designed for lightness and speed in moderate weather conditions, trail running jackets are designed with technical membranes and closure systems that prevent water ingress while allowing sweat to evaporate, which is crucial for maintaining thermal comfort during long hours outdoors. These jackets may also feature practical adjustments such as adjustable hoods, elastic cuffs, and reinforced seams for increased durability against the rigours of the terrain.

Men's and Women's Running Jackets

In the realm of trail running, jackets are carefully tailored to accommodate the anatomical differences between men and women, greatly influencing the fit and design of each model. Men's jackets are often designed with broader shoulders and a straighter shape, while women's jackets are typically tapered at the waist to better fit a curvier silhouette. This distinction is crucial as it affects not only the appearance but, more importantly, the comfort and mobility during the run. Additionally, manufacturers adjust the position and size of pockets, as well as the shape of closures to maximise accessibility and reduce distractions, allowing every runner to focus fully on their effort without discomfort. The fabrics used are also chosen to offer optimal range of motion and efficient body temperature regulation, ensuring that trail runners of all genders can find the jacket that fits their bodies perfectly.

Choosing the right trail running jacket

Selection Criteria for Your Trail Jacket

Weather Protection (Wind, Rain, Snow)

The ability of a trail running jacket to withstand elements such as rain, wind, and occasionally snow, is fundamental for any endurance runner. Waterproofness and breathability are the pillars of this protection. Jackets designed for severe weather conditions must offer excellent water repellence while allowing for the evaporation of sweat to prevent overheating and internal condensation.

Advanced materials like Gore-Tex are essential to keep the runner dry and comfortable, as well as waterproof zippers and taped seams to enhance protection. Practical adjustments such as adjustable hoods and elastic cuffs also contribute to better protection and comfort under various weather conditions.

Comfort and Range of Motion

A trail running jacket must provide complete freedom of movement, essential for navigating rough terrains. Whether it features an athletic fit to reduce wind resistance and maximize thermal efficiency, or a looser fit for increased comfort on long outings, every detail matters. Ergonomic hoods are crucial: they should fit perfectly, even when wearing a hat, and pack away easily without creating excessive bulk.

Ventilation Systems

Regulating body temperature is crucial during long trail runs. Passive ventilation systems, such as mesh panels integrated into key areas, play a vital role in enhancing the jacket's breathability. These areas allow for the continuous release of warm, damp air and facilitate the intake of fresh air, contributing to natural cooling and increased comfort during exertion.

In some models, this ventilation can be supplemented and controlled by strategically placed zippers, such as under the arms or along the sides. By adjusting these zippers, runners can more precisely manage heat buildup and maintain an ideal body temperature without stopping to remove layers.

Weight and Compactness

The weight of the jacket is a critical factor in selecting trail gear: a jacket that is too heavy can tire the runner and negatively impact performance. Thanks to advances in modern materials, it is possible to design jackets that combine lightness and durability. These jackets are not only effective in protecting against the elements but are also designed to be compact, taking up very little space in a trail running backpack. This small footpring ensures that the jacket can be easily carried without burdening the runner, remaining discreet and accessible only when needed.

Storage Options (Pockets)

The pockets of a trail running jacket must be designed to offer easy and secure access, allowing runners to quickly retrieve their nutrition, phone, or keys. The waterproofness of these compartments is crucial to ensure that the contents remain dry and protected, regardless of weather conditions.

Safety (Reflective Elements)

Visibility is a safety concern, especially for those who run early in the morning or late in the evening. Strategically-placed reflective elements on the jacket ensure that the runner is visible from a distance to other road or trail users, thus improving their safety in low-light conditions.

Détails veste de trail

Waterproof, Breathable, and Windproof Jackets: Stay Dry in Any Weather!

Waterproof trail running jacket

Waterproofness: Schmerber Rating Explained

The Schmerber rating, named after hydrologist Charles Edouard Schmerber who developed it, is a key measure in evaluating the waterproofness of fabrics used in outdoor gear. This rating is expressed in millimetres and measures the water pressure that the fabric can withstand before water starts to penetrate.

For example, a rating of 10,000 mm means that the fabric can withstand the pressure of a 10,000 mm high column of water. A jacket with such a rating offers good protection against moderate to heavy rain, making it suitable for most trail running conditions.

For extremely wet conditions or long runs in the rain, jackets with higher ratings, such as 20,000 mm or more, may be preferable to ensure total protection. Choosing the appropriate rating should take into account the typical weather conditions and the intensity of the planned activity, ensuring that the jacket is not only waterproof but also suited to the environment and intended use.

Breathability: MVTR and RET Explained

The breathability of a fabric is crucial for sportswear as it directly influences the wearer's comfort by regulating body temperature and reducing internal condensation. It is primarily evaluated in two ways:

  • MVTR (Moisture Vapor Transmission Rate): This measure indicates the amount of water vapor the fabric can expel over a 24-hour period, expressed in grams per square meter (g/m²/24h). A high MVTR signifies superior breathability, allowing rapid evaporation of sweat. For example, an MVTR of 30,000 g/m²/24h indicates an extremely breathable garment, ideal for hot and wet conditions or intense activities, while an MVTR of 5,000 g/m²/24h would be considered less breathable, sufficient for less intensive activities or colder climates.

  • RET (Resistance to Evaporative Transfer): This index measures the resistance a fabric poses to the evacuation of water vapor. The lower the RET, the more breathable the garment is. A RET below 6 is considered very breathable, ideal for intense activities where sweat production is high. Values between 6 and 12 are suitable for breathable garments used in moderate conditions, while RETs between 12 and 20 indicate limited breathability, and above 20, the fabric is considered non-breathable.

Understanding these measures helps trail runners choose a jacket that meets their specific needs, ensuring that sweat is properly managed to keep the body dry and comfortable.

How to Know If Your Jacket Is Waterproof?

Tags and Product Specifications:

The first thing to check is the jacket's labels. Manufacturers often indicate the fabric's waterproof rating, measured in millimetres (mm) using the Schmerber rating previously discussed. A rating of 10,000 mm or more is generally considered good for most weather conditions.


Waterproof jackets are often made of materials like Gore-Tex, nylon, or polyester treated with hydrophobic coatings. These materials prevent water from penetrating while allowing sweat to escape.

Seam Design:

Check if the jacket has sealed seams. In a quality waterproof jacket, all the seams where fabric pieces are stitched together are sealed from the inside with waterproof tape. This prevents water from seeping through the needle holes left by stitching.

Water Spray Test:

If you want to test the waterproofness of a jacket you already own, you can perform a simple spray test. Hang the jacket and spray it with water. Observe if the water drips on the surface and runs off, or if it starts to soak into the fabric. If the water beads up, the jacket is still waterproof.

Checking Zippers and Flaps:

Waterproof jackets often feature waterproof zippers or flaps that cover the zippers to prevent water ingress.

Field Test:

For a more rigorous test, simply wear the jacket in the rain or during an activity where you are exposed to water. Check after a while if the inside of the jacket remains dry. If water does not penetrate, the jacket is effective.

Waterproof trail running jacket

Choosing According to the Type of Outing and Seasonality

Short Runs VS Ultra Trails

The duration and intensity of the run directly influence the choice of jacket. For short trail runs, a lightweight and minimalist jacket is appropriate, providing essential protection against wind and light rain while remaining breathable. In contrast, for ultra-trails, which require endurance over long periods and in varying weather conditions, a more robust jacket is necessary. This jacket should offer better waterproofness, sealed seams, effective ventilation systems, and additional safety features such as reflective elements for night running.

Thermal Jacket for Winter

During winter trail runs, where temperatures can drop drastically, a thermal jacket is essential. These jackets often incorporate insulation such as Primaloft, known for its ability to retain body heat while offering excellent breathability. Primaloft insulation is designed to perform even in wet conditions, not retaining water and drying quickly, which is crucial for maintaining warmth in cold environments. Besides protecting from the cold, these jackets are designed to evacuate excess body heat and moisture, preventing overheating during intense physical activities. This allows the trail runner to remain comfortable, dry, and warm, enhancing performance and safety during winter outings.

Mandatory 10,000 Schmerber Jacket for the UTMB

To participate in the Ultra-Trail du Mont-Blanc (UTMB), one of the most demanding trail running events in the world, it is required to wear a jacket suitable for extreme mountain weather conditions. The jacket must have a hood designed to withstand bad weather and be designed with a waterproof and breathable membrane. The minimum recommended specifications are 10,000 Schmerber waterproofness and breathability with a RET below 13. Additionally, the jacket must have sealed seams to ensure maximum water protection and should not contain any non-waterproof fabric parts, except for the vents provided by the manufacturer, such as those under the arms or on the back. The hood must be built-in or attached to the jacket with a system originally provided by the manufacturer.

Trail running jacket guide

Recent Technologies and Innovations

Differences and Advantages of Gore-Tex and Primaloft Technologies

Gore-Tex and Primaloft are two of the most advanced materials used in sportswear manufacturing, each with distinct characteristics suited to different needs.

  • Gore-Tex is renowned for its ability to provide waterproofness and breathability. This technology uses a porous membrane that blocks water from entering from the outside while allowing sweat to escape from the inside, which is crucial for staying dry while avoiding overheating during physical activity.
  • Primaloft, on the other hand, is a synthetic insulation technology known for its light weight and thermal efficiency. It offers excellent heat retention even in wet conditions, as it absorbs very little water and dries quickly. This insulation is perfect for trail running in cold weather where maintaining body heat is essential.

Eco-Friendly Design

In the field of trail running gear, innovation is no longer limited to technical performance but also encompasses significant sustainability practices. Increasingly, manufacturers are incorporating recycled materials into the design of their jackets, meeting a dual requirement: maintaining high functionality standards while reducing environmental impact. These recycled materials, often sourced from recovered plastics or pre-existing textiles, are transformed into high-quality fibres that meet the same criteria of durability, waterproofness, and breathability as virgin fibres. In addition to reusing waste, this approach reduces energy consumption and carbon emissions associated with the production of new materials. Some manufacturers go even further by incorporating production processes that minimise the use of water and harmful chemicals and offering take-back or recycling programs at the end of garments’ life.

Trail Running Jacket Care

Washing and Drying Tips

To ensure that your trail running jacket maintains its performance properties, it is crucial to follow the specific washing and drying recommendations provided by the manufacturer. These tips are especially important for jackets made with technical materials like Gore-Tex or Primaloft, which require special care to preserve their waterproofness and breathability:

1. Washing: Most jackets should be washed in cold water with a mild detergent designed for waterproof fabrics. Avoid fabric softeners and bleach, as they can damage the waterproof membrane and alter the fabric's breathability.

2. Rinsing: Make sure that the jacket is thoroughly rinsed to remove all detergent residues, which could inhibit the technical properties of the fabric.

3. Drying: Air dry the jacket or use a low-temperature tumble dryer if recommended. Tumble drying at a low-temperature can revitalize the fabric's water-repellent finish of some jackets.

4. Re-waterproofing: After several washes, it may be necessary to reapply a water-repellent coating to restore the jacket's original waterproofness. Follow the manufacturer's instructions for applying a suitable re-waterproofing spray or lotion.

Tuto veste de trail