When I start managing someone's training, one of the big differences they notice is how much lighter I make everything. In my experience, most people put way too much emphasis on the intensity of a single session. Read on to learn why 'starting too light' is a critical principle for longterm success.
The Ladder Analogy
My favourite way of explaining the training process (and the importance of starting light) is The Ladder Analogy. The top of the ladder is our goal, and each rung represents a single training session. Each session moves us closer to our goal. However this only works if we keep a firm grip on the ladder and just try and take it one step at a time. When I train someone or write a programme, the goal for that session is just to move up one rung. Do this for weeks and months on end and you make huge progress. Unfortunately, the more common approach from most trainees is to: 1) Skip the first few rungs and leap to a third of the way up, and then 2) try to go up multiple rungs in a day. They continue this until 3) they become so tired that they fall down the ladder and have to start all over again. In the gym this looks like starting too heavy, and trying to make too much progress in a single session. All this ever leads to is a big ol' plateau just a few sessions into a programme, and sometimes so much fatigue that you have to take a light week and start all over again.
Starting light does a few very important things: 1. Avoid plateauing too early (as discussed above) 2. Allows time to hone technique in the first few weeks 3. Builds confidence from having multiple good sessions 4. Gives your body ample time to adapt 5. Allows you to gain for longer So, the question you're probably wondering: "how light is light enough?" There's no hard and fast rule, but a good starting point for a main lift (squat, bench, deadlift) is to figure out what you can comfortably do for 5 reps. Then take 10kg off that and start from there. Remember, comfortable means it's easy, not a 5 rep max. There's never almost never a downside to starting too light. If you truly did start much too light, it just means you have a few extra rungs to cover before you reach the top of the ladder. But you'll still get there all the same.