A deload is a planned step back from the volume (sets x reps) or intensity (load on the bar) in your current program. The idea is to give your tissues and nervous system a chance to recover after a period of intense training.
For advanced lifters (or individual training styles like powerlifting) this is important because your tissues heal at different rates. Muscle tends to recover quickly from training sessions.
But other tissues like ligaments and tendons (which receive less blood supply and lack specialized cells that help remodel damaged tissue), recover much slower.
This is where most people get in trouble because ligaments and tendons won’t get sore like your muscles, but they receive just as much abuse from heavy training.
That’s why programs designed for advanced lifters plan in “deload cycles” to help reduce the stress on connective tissue and give it a chance to catch-up to muscle adaptations.
However, most of us are not advanced trainees, powerlifters, or following high-frequency (training 5-6x a week) programs that use heavy loads.
If you’re working out 3-4 times a week, the other 3-4 days should provide adequate recovery time for both your muscles and connective tissues.
Between vacations, travel for work, sickness, and family commitments, we’re often forced to take a few days off here and there over the year.
Take advantage of these opportunities. Train hard up to your event and then let the time off serve as your deload.
So bottom line: If you’re crushing it with high training frequency, then schedule in deloads — your all-important connective tissues will thank you.
But if you’re training less (3x/week or less), then you likely don’t need to worry too much.