Fast Responders versus Slow Responders: The Health Factor
by Alan Couzens, MS (Sports Science)
In a recent article I looked at some of the differences in training responses that I’ve witnessed for different athletic “types.” I concluded that there are some differences in how quickly various athletes respond to a training stimulus that are related to genetic type. While we can’t do a whole lot to change our genetics, there is another factor that dramatically affects how we respond to training over which we have much greater control.
A number of studies have investigated the link between general health, life stress and training response and found a significantly negative relationship (Rushall, 1990) or maybe more precisely a balanced relationship. The body’s stress response is called the general adaptation syndrome for a reason -- in other words, irrespective of your genetic endowments, if you’re not living a healthy, low stress life, your ability to respond to training will be compromised.
This “non-response” is at the extreme represented by the classic notion of overtraining where the athlete’s adaptation reserves are exhausted to the point that clinical symptoms are observed, the athlete is chronically fatigued and can no longer recover from even modest physical exertion due to actual damage to the recovery structures of the body. In the same way that a diabetic individual’s pancreas can be exhausted to the point of damage, an athlete’s adrenal cortex can be exhausted to the point of damage if it is chronically stressed (via athletic or life stress) without appropriate recovery. In the athletic context, we call this “failing adaptation” or the dreaded “overtraining syndrome.”
However, similar to my position on non-responders versus slow responders, I don’t see the relationship as binary. Just because you’re not suffering from the clinical symptoms of overtraining/adrenal fatigue does not mean that you’re training optimally! Again, using the diabetes metaphor, long before the pancreas is damaged, the body becomes insulin resistant, that is, the hormone is so present that the body’s response to it becomes compromised. Similarly, long before getting to the point that the stress response structures are damaged, if cortisol is continually secreted, they get tired and this creates a significantly compromised response to training stress.
This is shown graphically as “compromised adaptation” below using actual data from a busy, less healthy moderate volume athlete (CTL/ATL constants of 42/16) compared to the sort of training response that we see from a typical healthy moderate volume athlete (CTL/ATL constants of 42/13), an athlete who prioritizes facilitating recovery from training sessions (good nutrition, sleep, stress control/management).
You can infer the correlation from the legend in the chart (failing adaptation / compromised adaptation / normal adaptation) to non-responder / slow-responder / fast responder. [Click for larger view]
Clearly, small changes in the time that it takes to shed fatigue add up quickly to decreased performance levels, especially when the greater recovery demands aren’t accommodated with shorter work cycles and longer recovery cycles.
A responsive athlete undergoing an appropriate load will exhibit a slight performance decrement early in the block followed by a progressive improvement as their body rallies and adapts to the load this is facilitated by planned recovery at the conclusion of the block). An athlete who is more generally fatigued will exhibit less response to training load, both positive and negative. An athlete who is too fatigued or stressed to deal with the stimulus will exhibit progressively worsening performance over the course of a training block. When this performance drop exceeds approximately 5%, the athlete can be considered to be in an over-reaching state (Hedelin et al., 2000; Halson et al. 2001) that is, the load is likely exceeding his or her adaptation reserves. When performance doesn’t recover after an unloading period of normal length, the foundations for overtraining are laid.
These performance decrements can be complicated by the HR paradox, where, due to hypervolemia, HR is often lowered for a given power/pace when the athlete is over-reached. In fact, in the Hedelin study mentioned above, a decrease in heart rate reserve of approximately 7% corresponded with a decrease in resting cortisol levels (a sign of failing adaptation) of 27%. Therefore, the message becomes when HR is consistently either high or low for a given power/pace output (outside of the typical zone), when maximal efforts are compromised by 5% or more or endurance is reduced by 50%, that is, the athlete is having a hard time doing a 2.5 hour set at his or her best 5-hour power: caution should be exercised, recovery should be prioritized and consideration should be given to modifying the training plan.
Of course, given the choice, the middle option is always the best -- when over-reaching is frequently observed, recovery/removal of non-training stressors should be emphasized as much as possible. An athlete who is able to do this -- sleep more, decrease non training stress is usually going to be able to absorb more training and is going to reach a higher performance level. That said, a sensible busy athlete who recognizes the limitations of his schedule/non athletic life and balances training and recovery appropriately is generally going to beat a busy athlete who tries to “cram it all in.” As the General Adaptation Syndrome implies, something will eventually give.
I have personally witnessed this in tracking the relationship between training load and performance in busy age-group athletes, the relationship between load and performance changes with the athlete’s life situation. A reduction in the rate of fitness improvement from a given training load of 30-50% for busier athletes is not uncommon. Consequently, athletes training on the edge will frequently get more fitness “bang” for their training “buck” by backing off a little and trading a small portion of their training time for some proactive recovery time that facilitates the ability of their system to deal with the stresses of training and living! In some cases, more isn’t always more.
Similarly, in a long term sense, big improvements in fitness are best facilitated by long periods of uninterrupted training. Obviously, a fast responder who is also subject to big gaps in training due to illness, injury or burnout can very quickly become a slow responder!
I’ve heard some say that elite athletics is an inherently unhealthy endeavor. I don’t agree with this. At the highest level of elite athletics, health becomes a priority as a matter of necessity. Those athletes who last a long time and are able to perform consistently at the highest level are inherently aware/obsessed with the importance of health. It is no coincidence that coaches/wellness specialists like Phil Maffetone have been behind some of the most consistent, highest performing triathletes of all time. When it comes down to it, achieving your true potential in any field is built on a strong foundation of health.
Train (and live) smart