Training with a bergen without wrecking yourself
Build hill fitness unloaded first, then add weight gradually and late in the block. Most load-carriage injuries I have seen came from someone loading heavy in the first weeks. Walk fast before you tab, pack the weight high and tight, and treat feet as part of the training rather than an afterthought.
Unloaded hills first
Weeks of hill walking and easy running with no weight builds the tendons, ankles and calves that load carriage punishes. Skip this and the bergen finds whichever one of them is weakest.
Add weight slowly, and late
Small increments, one loaded session a week to start, on ground you know. If your walking pace collapses when the weight goes on, the weight is too heavy for now — that is information, not failure.
Pack it like it matters
Weight high and close to your back, nothing that shifts, nothing that digs in, and the same pack every time so your body adapts to one thing. Fill space with kit you will actually carry rather than loose plates that move.
Feet are the whole game
Boots broken in over many sessions, socks you have tested for hours, and a hotspot dealt with the minute you feel it. Every long-distance thing I have done — ultras included — came down to feet before fitness.
Recovery is part of the load
Loaded sessions cost more than their distance suggests. One a week, an easy week every fourth week, and honesty about niggles. Selection punishes the injured far more reliably than the unfit.
A note on accuracy
Entry criteria, standards and selection dates are set by the Army and change over time. Take anything current from the Army's own UK Special Forces Reserve pages; take everything below as one applicant's experience.
Get my 21 SAS reserve selection prep guide
What the stages are, what I was training to before I applied, and how I'd build the twelve weeks before a selection weekend. Written from my own application, free, no pitch.