Central versus Peripheral Training and Adaptations
Archive post from 7/25/22
I had a good conversation at Craftsbury recently with a few rowers about the difference between central and peripheral strength training adaptations, and why this matters in our training.
Central strength training adaptations have to do with the central nervous system. How quickly and effectively can the brain and spinal cord transmit a force-producing impulse to the rest of the body? When you decide (consciously or subconsciously) to make a forceful movement, the central nervous system determines how much force and how quickly the force develops.
Peripheral strength training adaptations are to the muscular system. We can only transmit a big, rapid impulse from the central nervous system if the impulse has somewhere to go. The muscular system needs to be strong and coordinated to turn the impulse into force through a specific movement pattern.
Strength training needs to address both central and peripheral adaptations. However, the training for one system is not usually also the best training for the other system. For people new to strength training (young and old), both systems will improve together in the early stages of training. The training is all new to the body, so adaptation occurs quickly and broadly for the first few or several months. After this point, we need to be more specific in our goals and methods to achieve the desired adaptation.
We do strength training for central adaptations with higher outputs and shorter durations. This means bigger exercises like squats, deadlifts, and push presses where we’re training to send a big force impulse coordinated across multiple bodyparts. This also includes plyometric exercises where we’re training to send a very rapid force impulse. We use lower reps (1-5) to keep the output high before fatigue sets in.
We do strength training for peripheral adaptations with more moderate outputs on smaller exercises that are more focused on specific muscles. If we just do squats, deadlifts, and push presses, then only those major muscles contributing highly to those movements get stronger. We leave behind smaller muscles requiring more specific development, and we don’t tap into the growth potential of the longer time-under-tension of the 6-15-rep range.
You can probably see the periodization picture coming into focus here. We need to build the muscular system to receive the impulse from the central nervous system. We also need to train the central nervous system to develop and deliver a big impulse to the muscular system. We build up the muscular system more in the off-season with more moderate outputs spread over multiple bodyparts, then shift to more central nervous system training with higher force and power outputs as the in-season performance phase nears. (Read about why I don’t do “strength-endurance” in-season training here.)
Think about this as a continuum from central on one side and peripheral on the other. We can never reach pure central or pure peripheral, because the two elements interact intimately. Central nervous system force impulse directs peripheral muscular output, and peripheral muscular output is the only means of expression for central nervous system force impulse.
We will always be somewhere in-between our two theoretical poles of central and peripheral, and rowers can choose the specific “location” based on season and primary goals.
My approach is to spend the first few months of strength training mostly focusing on the central side, because we need to train full-body movement coordination before we can effectively focus on building individual parts. If a bodyweight row or pushup from a high hand position is still challenging, these will offer greater gains than doing more isolation exercises like machine rows and biceps curls, or chest flies and triceps extensions. There isn’t a big enough growth stimulus from isolation exercises with light weights to create significant physical change.
After the first few months of building athletic and nervous system coordination, we can then shift to more peripheral, specific muscular work with rowers who are more in the off-season than the in-season. Younger rowers with gaining muscle as a higher priority goal should generally do more peripheral work. Older masters rowers and lightweight rowers for whom gaining muscle mass is not a priority goal can continue to be more on the central side to focus on neural coordination gains.
You’ll also see the central-peripheral distinction used in discussions about aerobic system training. Central adaptations are generally to the heart and lungs to do with cardiac output. Peripheral adaptations are to the structures toward the extremities affecting oxygen uptake and use, such as the capillaries and mitochondria in the muscular system. Here the trend is reversed from strength training: Central adaptations tend to be more general and transferrable, while peripheral adaptations tend to be more specific to the movement pattern. The central system (heart and lungs) cardiac output powers all aerobic activity, but different modes of training emphasize different muscles (eg. biking, running, rowing, etc.) and therefore have different peripheral characteristics and adaptations.
My takeaway here is that we can cross-train for low-intensity training for general aerobic training for the heart and lungs cardiac output, and then focus specific rowing and erging training more for the peripheral structures’ uptake and use.
