Your body obviously has a crazy reaction going on when you exercise. Based on your experience level and a bunch of other variables, it will react to training stimulus in different ways. Everyone is built differently from a muscular standpoint and wired differently from a neurological standpoint. There are those who are react well to a ton of reps and those that react well to very low reps. Some can’t stand the thought of doing 5 sets of a given exercise in a day, while others can do 10 and be craving more. Since I am not one to bore you with “smart talk”, I will attempt to address the issue of neuromuscular adaptation as simplistic as possible.
One thing is for sure, in order to maximum results with your workouts you have to allow the muscles to adapt. What I mean by this is that you must let your body get used to a certain workout before moving on. However, there is a fine line between letter your body get used to it and letting your body get sick of it.
Lets say it is week one of your new workout kick and its been a year since you've worked out. For you to do 3 or 4 days of workouts in that week and then get into the following week with a whole new workout would be foolish. Why? Because you can’t expect your body to be working perfectly the first time it is doing those exercises. Think about any physical task that you have started up. Was your first day of doing that task your best day? The first time you shot a basketball or went for a job or even went bowling, I doubt were your best performances. Your muscles need time to “talk” to your nervous system and figure out the best way to do it. It will likely take more then one workout for your muscles and nervous system to get that conversation running smooth.
What To Do: When you get started on a new workout, stick with the same exercises for a few weeks in a row. This doesn’t mean that every workout should be the same if your are working out multiple days a week. If you are working out three days a week, pick three different workouts and stick to those. In order to maximize your results, you need to change the parameters of sets, reps, tempo and rest each week. The main idea is usually to be either lifting more weight, doing more reps or taking less rest; dependent on what your goals are.
After a few weeks of performing a consistent workout you absolutely have to change it up. Some people don’t like change, and this is why they look the same for years even though they workout consistently. Since I was talking about sports earlier and how your first attempt at that sport likely wasn't the best, I’ll use another sports example here. Think about baseball players and how they go into hitting slumps for extended periods of time. If you perform the same workouts for months and months you will go into a “physical slump”.
What To Do: Avoid the workout slump by changing your workouts every 5th week. Think of it as the start of a new month and start of a new workout. Don’t just change the exercises, but change the way you are working out. If you were previously doing one exercise at a time then resting, look into a super-set or circuit style workout. This is when you perform a few exercises together without rest, then resting after the final one. No matter what you do, make sure your new workouts aren’t too similar to your previous workouts.
The thing to take away from this is that you want your body to be able to understand a workout and learn how to optimize it. At the same time you don’t want to do that workout so much that your body gets completely sick of it and starts being counter productive.