Metabolic stress is one of the main mechanisms driving muscle building. Understanding how it works and how to optimize it will bring you more muscle gains!
In this 5min read you´ll learn how to apply different strategies to optimize metabolic stress and muscle hypertrophy
Mechanisms of Muscle Hypertrophy
Muscle hypertrophy is mainly caused by three mechanisms: mechanical tension, metabolic stress and muscle damage.
Going to the gym and programming your training to follow these mechanisms will make you able to optimize your gains and looked jacked next summer.
Mechanical tension is the kind mechanism of muscle hypertrophy, but metabolic stress is the other side of the coin.
Metabolic stress is required to induce and potentiate muscle hypertrophy, and our training program should take this into consideration.
What´s Metabolic Stress?
Metabolic stress is the physiological process that occurs during exercise in response to low energy that leads to metabolite accumulation in muscle cells.
These metabolites are mainly lactate , phosphate inorganic, and ions of hydrogen.
The metabolite accumulation leads to hormonal release, hypoxia, reactive oxygen species production and cell swelling.
These will cause the acute oxidative and inflammatory response to training, and future adaptations and muscle hypertrophy.
Consequences of Metabolic Stress
You may have seen many times a huge guy lifting 'low' load (compared to his dimensions), and he still builds muscle mass overtime.
Why are low loads able to induce muscle hypertrophy?
Increases muscle fibre activation
We have different types of fibres depending on the ability of contraction (source).
Fast-twitch fibres were believed to be successfully contracted only under high intensities and loads. But that's not how it is. Low loads and higher reps showed an activation of these fibres (study).
This happens because of the accumulation of metabolites, mainly ionic hydrogen, inhibiting muscle activation and calling for the recruitment of more muscle fibres.
The accumulation of H+ is telling our body is to activate more fibres because the already activated are not able to function at their best to carry out the task required (source).
There are other causes that may be able to increase muscle fibre activation. These are reactive oxygen species and hypoxia conditions (study).
Hormones play an important role in the anabolism and building of new muscle fibres.
The build-up of metabolites may increase the hormonal production post-exercise and induce a greater anabolic response (study).
In this study, the metabolic stress group showed higher production of growth hormone, epinephrine and norepinephrine.
The hormones that seem to induce the greater anabolic response are growth hormone (GH), insulin-like growth factor 1 (IGF-1) and testosterone.
Myokines are cytokines produced and released by muscle cells during muscle contraction. They are implicated in the paracrine regulation of muscle mass (source)
The main myokine regulating muscle mass is interleukin-6 (IL-6). It potentiates adhesion of myonucleus to muscle cells, increasing the number of sarcomeres and consequent muscle mass. (study).
Cell swelling, known as intracellular hydration, may positively induce muscle hypertrophy by an increase in cell satellite proliferation.
Cell satellites are stem-cells with no metabolic activity. They are waiting to be activated to join existent muscle cells and become a metabolically active cell.
If there is a higher intracellular hydration and satellite cell proliferation, muscle hypertrophy and anabolic response post-exercise will increase (study)
Reactive Oxygen Species Production
These compounds, also referred as ROS, are unstable molecules that contains oxygen and that easily reacts with other molecules in a cell (source).
When prolonged over time, ROS are associated with excess aging, inflammation and chronic deterioration.
However, ROS from exercise act as a signal for potentiating the anabolic response (study).
ROS may induce muscle hypertrophy via different metabolic pathways, such as MAPK (study).
Metabolic stress shows to increase acute ROS production post-exercise, potentiating anabolic signalling (study)
- Metabolic stress is the accumulation of metabolites in the muscle cells
- Metabolites accumulating are mainly lactate, hydrogen ions and phosphate inorganic
- The consequences of metabolite accumulation is an increased muscle fibre activation and increased production of anabolic hormones, myokines and ROS.
How to Optimize Metabolic Stress
In the next 5 min, quick tips to take to the gym and boost your crazy workouts!
Use low loads
For metabolic stress, the best you can do is to drop out some weight and go for higher reps, looking for that 'muscle-burning' feeling.
Go at around 40-50% RM, or the load that allows you to perform 12-15 reps to a high intensity degree.
Separate metabolic stress from mechanical tension
Both mechanisms act in synergy, but they have different requirements and mechanisms behind.
If you want to focus on one, it should separated from the other. For this, I usually follow two protocol:
- Do one training focused on metabolic stress and another one on mechanical tension
- Do the first part of the session with high loads (mechanical tension) and later start going for higher reps and lower loads (metabolic stress).
Leave metabolic stress for the end of the session
Metabolic stress induces fatigue. This could compromise your neuromuscular connections and efficiency of muscle fibre activation.
If you create a lot of fatigue before lifting high loads to induce mechanical tension, it is most likely that you won't be able to lift as much as we could if we were fresh.
Lower rest between sets
However, it's important that you feel totally recovered in each set to give your best and build up greater adaptations.
Resting 30s between sets may not be the best protocol when trying to induce muscle hypertrophy and metabolic stress.
You´ll still be so fatigated that the intensity during the next set will be far down under your limits.
What I recommend here is to take around 1'-1'30" of rest between sets.
Use of advanced techniques
Advanced techniques (dropsets, myoreps, rest pause) are a great tool in some specific cases.
However, if you are a beginner, I don't really recommend you doing them. Better to focus on doing a proper technique and feeling how your muscle is being contracted along the set.
Advanced training techniques increase metabolic stress by lowering rest time between sets or/and combining different stimulus.
Abuse of these techniques induce high levels of fatigue, compromising later exercises on the day.
If you are going to do them, put them at the end of your session.
Blood Flow Restriction
Blood Flow Restriction limits the pass of oxygen by using occlusion bands in your limbs.
This technique induces hypoxia conditions, one of the main consequences of metabolic stress.
If there's no oxygen available, there will be more metabolites being accumulated, and more metabolic stress as well.
BFR creates muscle adaptations even when using very low loads (20%RM)(study).
Use isolation exercises
To optimize metabolic stress, you should be focusing on isolation exercise with easy techniques.
You are looking for metabolite accumulation and the 'burning' feeling...
Just compare a leg press with a squat. Have you ever felt that burning doing a squat? And doing a leg press?
Isolation exercise are focused on training one solely muscle.
All the stimulus will go where we want it, achieving higher degrees of metabolic stress and local muscle hypertrophy.
Training Routines to Increase Metabolic Stress [FREE GIFT]
Before getting in the routine itself, I want to say clearly that your training should always be individualized and adapted to your needs, lifestyle and goals.
This being said, I created a training routine focused on metabolic stress for you to get an idea on how you could start your next gym routine.
In this excel sheet you'll find four examples of different routines, depending on how many days you are available to train.
How Can I Get My Routine?
Go to the button below, click and you have it!!
Can it get any easier? I really don't think so...
Besides mechanical tension, metabolic stress is the other main mechanism to induce and potentiate muscle hypertrophy.
Mechanisms behind metabolic stress are mainly metabolite accumulation, increased fibre activation, hormone and myokine production, and ROS acute response.
If you have any doubts leave your comment below in the comments section.