Stimulus: Why Your Addiction To a Certain Kind of Training May HALT Your Progress!

Written By Rich Maait

There are several areas in life where the law of diminishing returns is prevalent, one of the biggest and most misunderstood areas to which it applies is results from physical exercise. 

With every article I write, I try to give you guys information on topics that I find are coming up often in my day to day life as someone who coaches and trains people from beginners to advanced athletes. In recent years there has been a trend in conversations that I have with potential new clients, it goes something like “I joined X group fitness craze and got in (or was in) really great shape but after a while, I started losing muscle/gaining weight/getting injured”. 

We’re going to take a look at why this is so often the case (and why it sometimes isn’t), and how you can avoid it happening to you. I’m going to do my best to simplify these concepts and present them in a way that you can apply them to your own programming. There is definitely a way to acquire the results you want while engaging in the training that you most prefer, however it takes intelligent planning and a great deal of adaptability. 

Speaking of adaptability, that leads me onto the most important fundamental point about what may be killing your progress in the gym. “Adaptation” is a word that you’ll find thrown around a lot when your digesting information around health and fitness, but what does it really mean? Simply put, adaptation refers to the biological process of your body becoming better suited to its environment. Everything we do in life causes an adaptation, one of the most basic functions of the human body is that it detects changes in the environment and through various biological processes will make itself better equipped to handle these changes. In relation to exercise or physical activity, this change in the environment is what we would consider “stimulus”.  


To give you a bit of a better understanding of how your body deals with different kinds of training stimuli, it is important to understand the SAID principle. The SAID principle stands for specific adaptations to imposed demands. Meaning, as the name would suggest, that your body adapts specifically to the kind of demand that you impose on it. An easy to grasp example of this is the classic marathon runner vs. sprinter case. When you look at a marathon runner, they are lean and light, carrying very little muscle. When you look at the short distance sprinter, they carry large amounts of muscle. So, what gives? Obviously, they are both runners, the biomechanical movement they are performing is actually the same, the difference is the imposed demand. When a marathon runner starts putting their body through long runs, certain biological adaptations take place to allow their bodies to better handle this long, slower duration aerobic activity. These include increased expression of type one muscle fibres (slow twitch/endurance fibres) and improved aerobic fitness. When a sprinter trains their body to cover short distances in the shortest possible time, the adaptations their bodies undergo are completely different, they’ll see increased expression of type two muscle fibres, which are fast-twitch fibres that contract quickly and powerfully but fatigue very rapidly, sustaining only short, anaerobic bursts of activity.

Now that you have an understanding of the SAID principle, it’s important to ask yourself a couple of basic questions before beginning any kind of training program:

WHAT ADAPATATIONS DO I WANT? (What is my major goal?)


As I said before, a stimulus is a change in environment. So what would happen if in your environment you went to the gym three times a week and stood under a loaded barbell and squatted, or over one and grabbed it and deadlifted it from the floor? Your body would begin to adapt to this change in environment and become stronger (depending on your current strength level and rep ranges you perform these movements at – more on this later). If your programming, nutrition and recovery are in check you should be able to get slightly stronger every week. Let’s say you add 2kg to your deadlift every week, logic would dictate that you’ll be able to add 104kg to your deadlift every year, and in five years you will have added 520kg to your deadlift and you’re now the strongest person on the planet. 

I’m assuming that 100% of people reading this article picked up on my sarcasm there and realise that you’re not going to add 520kg to your deadlift, ever. But why does understanding this matter? It brings me back to the law of diminishing returns that I mentioned at the very start of this article. After a certain period of time spent chasing after a particular adaptation the body is going to lose its ability to keep adjusting to the particular stimulus. 

General Adaptation Syndrome (GAS) is a three-step process that describes the physiological changes the body goes through when under stress. While the initial research that identified this process was observing psychological changes that occurred when exposed to stressful events, the concept can be easily applied to physiological changes that we undergo when introducing a new stimulus. The first two phases are known as the alarm and resistance phases, the third is known as the exhaustion phase. What happens to the body in this exhaustion phase is the reason why you’re not going to add 520kg to your deadlift. We cannot have linear progression forever. 

I bet that by now you’re wondering, what does this all have to do with the title of this article or what I mentioned I have been observing through conversations with people about their experiences with certain kinds of exercise?

There are three main kinds of training stimuli:


All of these are different kinds of imposed demands and will force different adaptations. Let’s break these down in a really basic manner:

Hypertrophy stimulus is mechanical damage being caused to muscle tissue, the adaptation is growing muscle. Typically, the ‘rep-range’ for people looking for hypertrophy is 8 – 12 reps per set. 

Neurological stimulus is the brain firing correct muscle fibres to contract and oppose resistance, the adaptation is getting stronger. Typically, the ‘rep-range’ for people looking for neurological adaptations is 1-5 reps per set. 

Metabolic stimulus is the body generating the output of energy. The adaptation will depend on things like energy balance, but for our intents and purposes, let’s use the example of people going for the metabolic stimulus of losing body fat. If performing the same movements as when an individual is seeking hypertrophy or metabolic stimulus, the ‘re-range’ is usually 15 or more reps per set. However, metabolic training opens us up to a host of other movements (think battle ropes and prowler pushes). The key difference between a set being more for metabolic stimulus rather than hypertrophy is that if we are looking for metabolic output we are going to be avoiding the mechanical damage that we go after when we are trying to gain muscle. 

Hopefully, you can see how the three of these cross over. Obviously, in the early stages of getting stronger (neurological), muscles will grow (hypertrophy). Obviously, in the process of training to gain muscle (hypertrophy), the body will burn lots of energy (metabolic). However, it is important to understand that even though there is some degree of crossover (think of the three in a Venn diagram), if you have a specific goal you want to reach, you should be spending the majority of your time training in one of the three specific stimuli. 

This brings us full circle to my original point, certain people undertake a particular form of exercise, let’s use an example of a Functional Fitness class that always lasts 45 minutes, and they continue to make this their only form of exercise for months or even years at a time. These Functional, 45-minute classes are almost always at a very high intensity, and place quite a high metabolic imposed demand on the body. Now if we think about what I mentioned with regard to General Adaptation Syndrome, eventually people attending these classes regularly will reach that exhaustion phase and start to see largely diminishing returns from the stimulus they are putting their body through (exhaustion from metabolic stimulus will occur the quickest out of all three stimuli we are discussing here) and they’ll see things like muscle loss, fat loss stopping (even going backward due to stress) and a host of other biofeedback markers such as sleep, appetite and digestion negatively affected. 

So what does one do when they reach that point in their training? My favourite method is what is commonly known as a “deload”. The principle of deloading is often misunderstood as people tend to take it literally and keep on training with less load (resistance) as a means of letting themselves recover from these symptoms of exhaustion. However, my preferred way of deloading is actually just switching up the stimulus. This is usually more than enough to give the body a break and start a new GAS process. Herein lies the problem with fitness facilities that only offer one kind of training; they get people in, get them a decent result and hook them on the endorphin rush from high-intensity training, however there is no variance to the type of training they offer, so people end up run into the ground without even realising it and unable to get results.

I have a couple of loose guidelines that I use for deloading that you may find really useful. However if you feel like what I have outlined above has happened to you (it’s not only metabolic training that can do this, it happens just a frequently to people who push a neurological or hypertrophy stimulus too long also), it may be worth investing in a good coach who understands how to track your biofeedback and when to adjust your programming accordingly, it truly is worth the investment. Here is an example for each:

Hypertrophy – spend up to 12 weeks here (even 16 weeks for more advanced trainees) before deloading to a neurological phase for 2-4 weeks or a metabolic phase for 1-2 weeks.

Neurological – spend up to 6 weeks here before dealoading to a hypertrophy phase for 4-6 weeks.

Metabolic – spend up to 3 weeks here before deloading to a hypertrophy phase for 2-6 weeks. 

Please note these are very loose guidelines and I adjust these very dramatically from individual to individual. 

Being able to switch the stimulus when I need to for my clients is why I always recommend they have a membership to a commercial gym that will allow them to train mostly for their main goal but still get in other kinds of training too. A facility that has great bodybuilding equipment, as well as an area for metabolic training with different pieces of equipment, is definitely going to be your best option if your goal is changing your body composition. 

One other key thing to note is that if you are, or you are training someone who is, an absolute beginner, these rules don’t really apply as I have laid them out here. It’s not uncommon for someone to start training for the first time and see muscle growth, strength gains and a loss in body fat simultaneously. Although, as we covered from the get-go, that point of diminishing returns will be lurking, and it will be different for everybody, so keeping a close eye on what is happening week to week is still highly important. 

I hope this is a concise and easy to understand introduction to different kinds of training stimuli. Keep checking back as in a future article I plan to visit how to match your diet to the particular training stimulus you’re in to yield optimal results. 

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