High intensity training or HIT has been around for a number of years now with numerous highly acclaimed athletes advocating this approach. For example, no less than 6 time Mr Olympia, Dorian Yates built his physique using the principles of high intensity training, in conjunction with his indomitable mindset. Back in the 80’s and 90’s, this type of training was not mainstream and indeed, it was quite controversial as it required so few sets compared with the traditional style of training that called for much more volume in workload.
Traditional volume type workouts could last several hours with training up to 6 days a week in the gym and that was the accepted way of building muscle back then. Cardio exercise was also based on more volume with the traditional 1 hour session of treadmill or bike for example. It was the ‘conventional wisdom’ at the time and many people were conditioned by this. As a result, High Intensity Training was quite a controversial way to train. Fast forward to 2017 and we see various styles of high intensity training as being the norm, certainly with cardio training where research shows that HIT is as effective, if not more effective than traditional low intensity cardio sessions. HIT training to build muscle has also gained more traction in recent years and certainly not something to be ignored, particularly in light of the results that are being seen with HIT cardio. Lets take a closer look.
What is High Intensity Training?
It is what it says on the tin. Training with high intensity. By its very nature, you can’t do much of this type of training if you going ‘all out’ on the exercises that you are doing. Its like running. You can either sprint all out for 100 metres or you can pace yourself for the 10,000 metre race. The 100 metre sprinter puts everything into that 10 seconds or less and they are exhausted when they cross the line. The long distance runner can’t sprint out of the blocks for the first 100 metres or even the first 1000 metres.
They have to pace themselves over the long haul or they wouldn’t cross the finish line. So HIT training is about giving it everything in a much shorter time frame in the gym. Typically, on any given exercise, after warm-up sets, you’ll be training to failure and often beyond failure to totally exhaust the muscle. So for example, take the Bench Press. After warm up sets, your working set would be one set with a weight that you could achieve 7 or 8 reps. You would continue with each rep until you could no longer perform a rep on your own and your training partner helps you to complete the final rep. That is training to failure. Now you partner may help you with another couple of forced reps to really exhaust the target muscles. On some exercises, you may go beyond this with 'negatives' where your training partner helps you lift the weight so that you can control the weight down in the negative portion of the movement. This exercises the muscle in the eccentric phase and will totally exhaust the muscle. This would be classed as one high intensity set and you are unlikely going to want to do another set of the same exercise of you've given it everything. You’ve done the job and you move on to your next exercise.
What is the Rationale Behind the Theory?
The process and biochemistry of gaining muscle mass is complex, however, the principle is much more straightforward. If you overload a muscle and ask it to lift more than it has in the past, it has to grow. This is called the General Adaption Syndrome which is the predictable way the body responds to stress as described by a chap called Hans Selye. The General Adaption Syndrome has three stages as follows:
Stage 1: Alarm Reaction: The initial reaction to a stressor that causes an activation of protective processes. Resistance training creates stress on the body, such as increased amounts of force on the muscles, joints, connective tissues and also on the nervous system. When you first start weight training or when you are coming back to it after a layoff, you get muscle soreness the next day and perhaps some tiredness. You might even feel a little irritable. This is the alarm reaction. In clinical terms, this is observed as a "bodily expression of a generalized call to arms of the defensive forces in the organism" and is unavoidable. While some soreness should be expected at first, it doesn’t have to be so bad that you can’t get out of bed! The soreness, which is known as Delayed Onset Muscle Soreness or DOMS, is directly proportional to the intensity of the training. In Hans Selye’s words "The alarm response of the body is directly proportionate to the intensity of the aggression."
Stage 2: Adaptation: When the body is exposed to the same stress, it will adapt and increase its ability to deal with this stress. The body increases its functional capacity to adapt to the stress via super-compensation. Weight training basically puts a stress on the body and we can control how much stress by varying the intensity of our training. In order to send the signal for adaption, which is greater strength and larger muscles, then the intensity level of the training has to be high. How do we measure intensity and how do we know if we are making progress in intensity? Is it a case of doing more forced reps, negatives, drops sets and so on? I keep it simple. Progressive overload taken to failure.
If we go into the gym and we are lifting the same weight every week for the same number of reps and sets, then we are not sending the signal to adapt. There is no alarm reaction. With high intensity training, the objective is to apply a stressor that is greater than that of our last training session. For example, if we did squats with 350lbs for 8 reps last week on our working set, the objective this week is to do 350lbs for 9 or 10 reps.
This way, we are progressively overloading the muscle and sending the signal for adaption. If we do the same weight, for the same reps, then the body has no reason to adapt. Once we’ve sent the signal, our job is done on that exercise.
As we adapt and respond to stress in proportion to its intensity, we also use up reserves of adaptation energy in proportion to the intensity of the stress. We only have a finite amount of energy reserves which we tap into as we adapt to the stressor. We can replenish these energy reserves but it takes time. Its not just about replacing the glycogen in the muscles.. The Central Nervous System (CNS) has to recover as well. If we keep our workouts intense, but brief, as well as not too frequent, we’ll conserve our energy for recovery and adaption. If you are making good progress in your training, ie. You are getting stronger and bigger, then you know you are on the right track and the adaption process is taking place. However, things don’t happen in a linear fashion in this life and it is highly unlikely that we’ll be getting stronger in every successive workout. There are many factors involved in having a great workout where you are in the zone and firing on all cylinders. If you are under stress in your job, working long hours, not getting enough sleep, skipping on meals or dealing with any number of things in your life, this can have an impact on your training performance. There are going to be times when we just need to take our foot off the gas in order to keep the longer term gains moving in the right direction. If we don’t listen to our body, and keep going full tilt all the time, then it is likely we’ll be heading into the next stage of the general adaption syndrome.
Stage 3: Exhaustion: If the body or exposed to stress for too long, then it will enter in to the exhaustion stage. At this point the prolonged stress overwhelms our ability to recover and adapt. When this happens, you’ll cease to make any gains and you also increase the risk of injury. When you overtrain, you have reached the exhaustion stage. You’ll feel unmotivated and lethargic. If the situation continues too long, acute exhaustion sets in and you certainly won’t be going to the gym! This is why we need to have adequate time between workouts to allow full recovery otherwise, we keep draining our reserves and heading into overtraining territory. There are no gains to be found there. Here are the symptoms of overtraining that you need to be on the lookout for:
If you are experiencing these symptoms, then maybe it is time to take a break and let your body recover. Taking a week off from the training allows the body and mind to recover. When you return to the gym, you’ll no doubt be more motivated and focused.
High intensity training has many benefits not least it’s adherence to the principles of the general adaption syndrome. If you are not experiencing any gains recently, there could some reasons for that. If your training sessions are not intense enough, they won’t cause an alarm reaction, and no adaption will occur. If your workouts are too long and too frequent, you could be overtraining. Either way, gains will not be forthcoming. It is a fine line between adaption and overtraining and we want to do just enough to stimulate adaption and make the muscles grow and then we can focus on recovery in preparation for our next workout.
In the next article, we’ll take a closer look at a HIT training routine, with exercises, intensity techniques, training frequency, mindset, and recovery.
Sports & fitness nutritionist, researcher and author on a mission to improve the human condition. Focusing on evidence-based and outcome-based nutrition, training, mindset & environment