How-to: Muscle Damage
TL; DR Version:
1) Muscle damage occurs during all training sessions that are sufficiently challenging to stimulate muscle growth. It is a synergistic trigger for muscle growth along with mechanical tension and metabolic stress.
2) Muscle damage can, and should be produced, without selecting an overabundance of exercises that emphasize said muscle damage.
3) Exercises that emphasize muscle damage are eccentric (muscle lengthening while under load) focused.
4) The amount of damage incurred by the muscle must be recovered from before any new tissue can be built.
The final muscle building stimuli left to explore is muscle damage.
Muscle damage can be quite confusing. In a similar fashion that metabolic stress has an easily recognized feeling during exercise, the degree of muscle damage experienced by a trainee has a recognizable feeling after the workout. The sensation of localized muscle pain, stiffness, and often temporary loss of strength that occur in the days following a training session are all telltale signs that muscle damage has occurred, but what exactly does it mean and is it worth prioritizing?
We lift weights with our muscles. A single muscle is made up of countless individual muscle fibres (think striations you’d see on a cut of meat). At the smallest individual muscle fibre level, the mechanism that causes us to be able to produce force and ultimately lift weights is based upon a synchronous, repeated, series of attachments, shortening (contraction), and release, that occurs between two microfibre subcomponents.
While an imperfect metaphor, think of someone pulling a length of rope towards themselves hand-over-hand. Within each individual muscle, one micro-fibre (the person’s hand) attaches to a second microfibre (the rope) and shortens (pulls the rope towards the body) over and over until the rope ultimately reaches its endpoint. If this example was a biceps curl, one end of the rope would be attached at the shoulder and the other would be attached at the elbow. As the hand-over-hand rope pulling occurs, the elbow bends as the muscle fibres contract and produce force.
Now imagine if something started to challenge you by pulling the rope in the opposite direction. What would happen if the rope were to slide through your hand? This is muscle damage.
As the muscle fatigues, some of the attachment points between the microfibres begin to slip, or break. Gravity and the load of the weight you are lifting begin to fatigue the muscle to the point where these muscle fibre attachments can no longer sustain their effort and they begin to experience tiny tears.
In the same way that a difficult high-repetition set can give us the perception that we’re working hard, feeling a lot of muscle damage (delayed onset muscle soreness) in the days following a workout often make people believe that their training session was productive.
The problem is that muscle damage is a necessary evil but has a definitive point of diminishing returns. Muscle damage is crucial in mobilizing the body to recover from a hard workout. Inflammation, nutrient delivery, and the ultimate rebuilding of the damaged area is what causes our muscle to grow. But more is not always better.
At the beginning of each workout, you will start at a baseline level of muscle strength, size, and performance. By the end of the workout, you will have dug yourself into a performance hole due to the damage sustained during the session. The amount of damage that you sustain during the workout must be built back to baseline before any new progress can be built upon it. This is why we must be careful with the dosage of muscle damaging exercises we perform on the same muscle group per day.
While all exercises that are sufficiently difficult will produce some degree of muscle damage, certain exercises (or exercise types) are particularly notorious for damaging muscle tissue. Any exercise with an emphasis on producing for while a muscle is being lengthened (think a walking lunge) will have a higher degree of muscle damage associated with it. As you decelerate yourself into the bottom position of a walking lunge, your muscles are slowing your body (producing force) while also lengthening (stretching). This is the rope sliding through your hands in the previous metaphor, except this time, we are slowly feeding the rope through our hands intentionally.
As with everything, more is not necessarily better – better is better. In the following blogs we will explore how to structure workouts around these three stimuli in order to keep you moving forward efficiently. With this information in mind, you can arm yourself to create your own workouts under almost any circumstance.
Best,
Eric