Trail running drop bag essentials: what to pack for 50 and 100 mile races
Most runners spend months preparing their training. They log the miles, dial in their nutrition strategy, choose their shoes carefully. Then they pack their drop bags the night before.
It shows.
A badly packed drop bag costs time at the aid station, forces compromises mid-race, and can turn a manageable situation into a race-ending one. A blister developing at mile 40 takes five minutes to address; the same blister ignored until mile 70 takes forty. Done well, a drop bag is a small resupply depot that keeps your race on track without breaking momentum. The difference is mostly planning.
The logic of drop bag placement
The first decision is what each bag is for. In a 50-mile race with two stations allowing drop bags, the problem is different than in a 100-miler with six stations spread across the night. Think in categories of change, not in distances. Three events drive most drop bag use: environmental shift (daylight to dark, temperature drop, rain), physiological shift (foot swelling, chafe appearing, energy depletion), and gear degradation (failing batteries, saturated socks, depleted nutrition).
In a 50-miler, your bag at mile 35 serves primarily as a reset. Fresh socks, renewed barrier protection, headlamp if you'll finish in the dark, topped-up calories. You're not solving major problems; you're preventing them.
In a 100-miler, bags are more targeted. Early bags at miles 25 to 40 carry insurance. Mid-race bags at miles 50 to 70 carry the things you'll genuinely need: a jacket for the cold section, a headlamp battery swap, blister supplies you likely need by now. Late-race bags at miles 80 and beyond are streamlined. For races with crew access, the drop bag serves as backup. Without crew, it's your only resupply.
The foot care station
This is where most drop bag strategies fail. Runners bring nutrition. Runners bring headlamps. Runners underinvest in foot care, which degrades faster than almost any other system over distance.
Every drop bag beyond mile 25 should contain a complete foot care kit.
Socks. Two pairs per bag in races over 50 miles. Trail running socks designed for ultra-distance move moisture, reduce friction, and maintain padding through extended use, but only up to a point. After 20 to 30 miles in dry conditions, or after any significant water crossing, a fresh pair resets the system. Wet, matted sock fibers dramatically increase friction and the probability of hot spots developing into blisters.
Barrier cream. The most overlooked item in any drop bag. Most runners apply once at the start and consider it done. The science of what separates short-duration from long-duration formulations matters more over distance than most runners understand. Film-forming ingredients and occlusive bases behave differently after two hours under sweat load. Serious runners carry a small container and reapply at every major foot care stop. The broader picture of foot protection across the full distance covers when to intervene and what to look for before problems escalate.
Blister kit. A needle or lancet, moleskin or pre-cut tape, and a small pair of scissors. The detailed protocol for blister prevention and treatment across 100 miles covers what to pack, how to use it, and how to train your crew to manage the same procedures.
Nutrition, lighting, and clothing layers
Nutrition. Every bag should contain more than you think you'll need. Race-day appetite is unpredictable. High intensity reduces hunger, fatigue amplifies cravings, and the foods that worked in training may be unappetizing at 3am. Pack a mix: something dense and caloric, something easily digestible, something with sodium.
Electrolytes. A separate electrolyte supply beyond what's in nutrition. Hyponatremia from drinking plain water without adequate sodium is a real risk in long events.
Lighting. One fresh headlamp battery or a fully charged backup headlamp in every bag that covers night hours. Verify the chargers and batteries work before race week, not the night before.
Clothing layers. A lightweight base layer or wind shell for the cold section, a dry shirt for the mid-race reset, fresh gloves if morning hours will be cold. Everything going into a drop bag should be synthetic or wool.
What experienced runners always include that beginners forget
Barrier protection for non-foot areas. Thighs, underarms, nipples, and the contact points of a hydration vest all accumulate friction damage over distance. At mile 60, fresh barrier application to pack contact points prevents a problem that would otherwise grow for 40 more miles.
An inner bag pre-packed with aid station items. A small ziplock containing just the stop's essentials means you're in and out in four minutes rather than rummaging through a dry bag at 2am.
Anti-nausea. GI distress is among the leading causes of DNF in ultramarathons. Ginger chews, peppermint, or whatever works for you in training.
A phone battery or backup charge. For safety in remote sections, for accessing course maps, and because race-day emergencies occasionally require communication that a dead phone cannot support.
The complete drop bag checklist
Foot care (every bag beyond mile 25)
Fresh socks, two pairs · Barrier cream · Needle or lancet · Pre-cut tape or moleskin · Small scissors
Nutrition
200 to 400 extra calories per section · Electrolyte tablets · Backup nutrition variety
Lighting
Fresh headlamp battery or backup unit · Verified before race week
Clothing
Lightweight layer for temperature drop · Dry shirt for mid-race reset · Gloves if applicable
Administration
Pre-packed inner bag with aid station items · Phone battery or charger · Anti-nausea option · Sunscreen if applicable
Frequently asked questions
What should I put in a drop bag for a 100 mile race?
Every bag needs a foot care kit, fresh socks, renewed nutrition, and lighting supplies for night sections. The most useful shift in mindset: think about what you'll need at each specific station, not what you'll need in general. A bag at mile 35 serves different purposes than one at mile 75. Pack each station's bag separately, labeled for that stop.
How many drop bags can you have at UTMB?
UTMB typically allows one drop bag per runner, placed at one of the designated bag drop points around Courmayeur at approximately mile 50. Space and weight limits apply and change year to year. Check the specific year's race guide for updated rules. The complete UTMB preparation guide covers the full drop bag and crew strategy.
When should I change socks during an ultra?
Every 20 to 30 miles in dry conditions, immediately after water crossings when possible, and any time you feel persistent heat or friction that does not resolve within ten minutes of running. A sock change that prevents a blister saves far more time than addressing that blister at mile 70 with 30 miles remaining.