Training is all about adaptation! When we train, we are not merely exhibiting what we are capable of at that moment in time, we are attempting to provide a stressful stimulus that is great enough to drive our bodies to get better but not so stressful that we cannot recover from it. The principle of progressive overload gets emphasized a lot and while this principle becomes evident in good programming, the presence of progressive overload is only possible if the applied stress of lifting and the body’s adaptive response work in tandem to progress the athlete. These two things combined make the principle of progressive overload evident but simply “progressing” on paper for the sake of progressing without monitoring how much stress you’re applying and testing how your athlete is progressing isn’t enough. In particular, under dosing initial weeks and progressing over time looks like progress on paper but in reality it probably means that the first few weeks were under stressful, the middle weeks were appropriate, and the last weeks were over stressfull. Instead, what if each of those weeks was simply sufficiently stressful to drive adaptation, but not so stressful to crush the athlete?
The systems of the body respond differently to varying training inputs and their respective intensities and doses. Knowing what we want out of our training is the first step to determining what kinds of adaptation we want to drive, and what methods we will use to get there.
What are the kinds of adaptive response to exercise? Broadly, we can sort these into central adaptation and peripheral adaptation categories where central adaptations refer to adaptations of the central nervous system, and peripheral adaptations which refers to changes that happen in the tissue. When we list adaptive response like this it can make it seem like every exercise only addresses one adaptation which is not the case. Some kind of concurrent or blended stimulus happens on most exercises (i.e. most things are not 100% exclusively peripheral or exclusively central), but understanding what the primary kind of stress being applied by a method is important.
When I conceptualize a training program, I picture a mixing board where each lever represents a training input that can be dialed up or down to create the desired sound – or in the case of training a desired adaptation. Here the athlete is the musician, the coach the person at the mixing board, and the song or the end result is a by product of the athlete’s efforts and adaptation and the coach’s wisdom on what stressors to turn up or turn down at any given time.
Central vs Peripheral
Central adaptations can be defined as adaptations related to the nervous system and it’s output. Cardiac output*, neural drive to the motor unit of the muscle, and central fatigue mechanisms all fall under the umbrella of central adaptation.
Peripheral adaptations are defined as adaptations that happen in the peripheral tissues such as capillary density, muscle mass changes, mitochondrial density, and local metabolic adaptations.
*The literature on these topics is complex and the complete contributions of central and peripheral mechanisms on cardiac output (Q) are not completely clear, but we do know that cardiac output has central cardiac elements as well as peripheral tissue elements such as blood flow and vasodilation. For simplicity I have separated Q into a central adaptation category, but really it is somewhere between the two.
Athlete's Needs and Low Hanging Fruit
To contextualize these elements, a weightlifter who struggles with burning and fatigue on higher rep sets or who gasses during basic cardio, but who can repeatedly be strong and explosive on single reps is likely very neurally adapted but may benefit from central cardiac adaptations and peripheral tissue adaptations that would permit higher training volumes before metabolic fatigue symptoms set in.
On the other hand, a marathon runner who struggles with basic plyometric exercises and who isn’t very strong but who can run for ages without fatigue is likely very centrally adapted on their cardiac output and peripherally adapted in their capillary density, but may need some peripheral adaptations in their tendinous and muscular tissues as well as some central nervous system adaptations on their strength output.
These are simplified imaginary scenarios purely for illustration. In the real world, testing protocols and key performance indicators (KPI’s) should be implemented to establish performance baselines and understand where the athlete is and where they need to go. The process is an ongoing cycle of testing, finding the weakest link or the largest limiter to an athlete’s performance and addressing it, then re-testing finding the next limiter or new weakest link and addressing it – essentially, we rinse and repeat this cycle forever with nuances for when the athletes are in season, out of season, peaking, etc.
Testing and Training
Implementing testing protocols doesn’t have to be hard or complicated! Testing the athlete helps us determine how much neurological (central), tissue (peripheral), or metabolic (peripheral) oriented training is needed. Have a regular testing schedule for your chosen metrics and be mindful of what kinds of scores are happening when your athlete is performing their best in their sport. Different sports need different biases so individually profiling your testing protocols based on the needs profile of your sport is a good idea.
Below are a few of the common testing methods we can use, however this is not a comprehensive list of tests that can be used.
Reactive Strength Index
Dynamic Strength Index / Explosive Strength Deficit
Barbell or Sprint Velocity Measurements / Force Velocity Profiling
Maximal Strength
Repetition Endurance
Maximal Aerobic Speed Testing
Heart Rate Recovery
Estimated V02 Max
Estimated Anaerobic threshold
Resting HR Monitoring
HRV Monitoring
To implement testing, develop a needs profile of the sport or a needs profile of goals for a gen pop trainee. Determine what testing will monitor those needs. Implement a strategy, retest, and assess if improvements were yielded. Improvement here may mean a higher score on the test, however improving on our tests isn’t a guarantee that sport performance will improve so additionally monitoring if test improvements leads to sport improvements is a critical element of determining if that test is valid for the athlete in the long term.
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