Thursday, March 5, 2015

Stressors, Ergogenic Aids and Training Loads

Training Basics

Training always involves balancing stress and recovery. A stress is applied to the system, the stress results in a deviation from homeostasis, acting as a stimulus for cellular signaling that leads to adaptation. This adaptation will leave the system better able to cope with the stimulus in the future (demand for ATP, substrate transport, muscle recruitment, etc).

Generally, there is a dose-response to training so that the more training stress or training load encountered, the greater the signal and response to adapt. For example, if you had two groups of college kids, one group ran 10 miles per week (mpw) and the other group ran 30 mpw - after 10 weeks, the group that ran 30 mpw will likely outperform and/or show greater improvement over the 10 mpw group. Why? Because the 30 mpw group accumulated a greater training load resulting in a greater response.

Of course, that's a very simple example. When it comes to training at a higher level - more is not always better. The athlete who runs or rides the greatest number of miles per week does not always win. Instead, there has to be a balance of stress and recovery - a balance of stimuli contributing to perturbations from homeostasis and factors that can either prevent perturbations in the first place or time to return the system to homeostasis.

Ramping up the Signal
There are several strategies that are being used now to either enhance the signal or increase the training load. What's interesting is that these strategies use entirely different approaches. While training in a hot, high altitude environment will result in a decrease in training load, it may enhance cellular signaling leading to favorable adaptations. Same with training in a glycogen depleted state or with high levels of mental fatigue - training load will be reduced. At least in the acute phase, these strategies are anything but "ergogenic."

Altitude/Heat training
Training is a glycogen depleted or fasted state, low carb diets
Mental fatigue

Increasing the Training Load
Then there are those supplements and strategies that are ergogenic:

Beta-alanine
Creatine
Caffeine
Carbohydrate supplementation
Supplemental O2
Antioxidants?

Yes, there are plenty others - you could consider water an ergogenic aid.

If you think about it, these strategies can help prevent or delay disturbances. Beta-alanine can buffer H+; creatine provides substrate for ATP resynthesis; supplemental O2 prevents declines in O2 saturation at high intensities; carbohydrate prevents declines in muscle glycogen/blood glucose, etc. By preventing disturbances, these strategies and supplements can increase the amount of work an athlete can complete - increasing the training load an athlete experiences.

Balancing the Stressors
On the one hand, the system needs to experience perturbations - and these deviations from the norm can be enhanced by the strategies in the first category. On the other hand, these strategies may decrease the training load that individuals can accumulate. For example, a runner will not be able to complete as many intervals at a given pace in a hot environment while in a glycogen depleted state as a runner in a cool environment, sipping on a CHO beverage a few hours after a high carbohydrate breakfast.

What's more important? Inflating the training load with the help of these "ergogenic strategies" and supplements or maximizing metabolic stress while potentially decreasing training load?

Even if you take every precaution, can you really prevent perturbations from homeostasis and inhibit adaptation? Especially in elite athletes who know how to push themselves to their limits. Even if an athlete supplements with carbohydrate, he/she my still experience glycogen depletion - but after accumulating a greater training load.

And let's not forget that mechanical stress can also be a trigger for adaptation and by limiting training load, you limit mechanical stress.

In my research at Appalachian State, we looked at the effect of different oxygen concentrations on training intensity and performance at simulated altitude. Athletes completed intervals on a cycle ergometer in  either hypoxic or hyperoxic conditions. Predictably, those training under hypoxic conditions cycled at a significantly lower power output (expressed as a percentage of their peak power output). At the end of the 3 week study, those who had trained at greater power outputs, under hyperoxic conditions, improved the most in a time trial at simulated altitude. Why? One reason could be because they were able to accumulate a greater training load by riding at higher intensities. Their muscles would also have experienced greater mechanical stress while training.

From a psychological standpoint, I think it would be best not to train your athletes under additional stress (at least not without lowering their expections). When an athlete sees slow slow splits and struggles to complete the workout or cover the distance, that athlete will be mentally defeated - perhaps that defeat could have been prevented had the coach not been focused on maximizing metabolic stress. Wouldn't you rather have an athlete leave a workout satisfied and feeling as though it came easily?

I'm not here to say one way is right and the other is wrong. Different strategies may be appropriate at different times. Coaches and athletes need to be able to recognize this.

Further reading:
http://www.outsideonline.com/fitness/bodywork/in-stride/Should-You-Really-Train-Low-On-Carbs-.html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4008803/#CR22
http://www.jissn.com/content/6/1/5
http://www.vacumed.com/pdfs/Hyperoxic_Science.pdf

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