Do You Need a Logbook?
Whether trainers need a logbook isn't the hottest debate in the industry, but it's one we haven't settled either.
You could argue that a trainer without one is an instant red flag. We're paid to have a plan, and short of a photographic memory, nobody holds the plan for a full roster of clients in their head. I tested this on myself and worked without a logbook for six weeks. Remembering the program for more than a handful of clients turned out to be impossible, let alone last session's loads, reps and tweaks.
A trainer walking around the gym with a client but without a logbook just screams “making it up on the spot.” This is not a good thing.
Even so, I've watched some very good trainers work with no logbook at all.
Coach Benny teaching a class to look for detail in the setup and execution of a bicep curl
They play what's in front of them, train to the client's capacity on the day, and nudge simple programs along week to week. The catch is that this only holds at the two far ends of the ability range. It works with clients so limited that every week is a fresh experiment in what's possible. It also works with advanced athletes, long past the “progressive overload” phase, hunting tiny adjustments for the last one percent.
(By the way, our obsession with increased load is misplaced. Increasing external load doesn’t always correlate to increased internal stimulus.)
Often you'd see as much progress from sharpening execution instead. Load what you need to train a client to the edge of their ability and tolerance on the day, no more.
So, generally, a logbook is essential for tracking progress and ensuring an increase in strength (load) over time.
With a new client, plotting a gradual increase keeps you from blowing past their tolerance on the days they turn up feeling superhuman.
For experienced clients it might matter even more, since this is your record of the customized setups and the cues that worked, so the next session can be even more effective.
(You do customise exercises for individual clients, don’t you?)