Stress requires longer recovery after strength training

People suffering from chronic mental stress would be wise to take this into account when determining the necessary recovery time after strength training. This is the outcome of a study conducted by The University of Texas in Austin, the results of which will soon appear in the Journal of Strength & Conditioning Research (1).

Stress and Cortisol

Before delving into the research itself, let me first describe the role of the “stress hormone” cortisol. We’ve previously written about the relationship between cortisol and muscle breakdown. The aforementioned outcome of the research is entirely in line with what one would expect if familiar with the workings of this hormone.

Hormones act as messengers in the body, issuing instructions to various cells. Depending on the circumstances, the release of certain hormones can be increased to better enable the body to respond to those circumstances. For example, adrenaline is produced in acute emergency situations so that you can act faster and more alertly (“fight-or-flight response”). For instance, if a rattlesnake suddenly falls through the mail slot, your body will produce adrenaline.

However, if yet another bill falls through the mail slot while you already have last month’s bills lying around, your body will increase the release of another hormone, namely cortisol. Cortisol is a hormone that, under conditions of prolonged stress, helps the body provide extra energy for coping with it.

Stress can be seen as a burden that one feels they have no control over or a burden that exceeds one’s capacity (2,3,4). According to some theories, one does not always have to be aware of the accumulation of this stress. In this context, the Texans refer to research indicating that a disruptive level of stress can also arise from the accumulation of events of which one is not aware that they have such a mental impact (2,5).

Psychological stress has physical consequences. Previous research has shown that individuals who experience a lot of stress recover more slowly when they are sick (6,7).

Cortisol Acts Catabolically

Catabolism and anabolism are two processes between which the body can switch. In an anabolic state, the body uses available resources for growth and repair. By eating more than the body currently needs, the body can initiate anabolic activities through the action of the hormone insulin, such as the production of extra protein in the muscles, as well as storage of body fat. In a catabolic state, your body instead prefers to use available resources in the body to provide energy. For example, the recent part published about the aerobic energy system described how fats, as well as proteins in the muscles, can be used for this purpose to produce glucose (gluconeogenesis). The body will switch to anabolic mode in the case of a calorie deficit to provide enough energy for essential processes.

In this process, various hormones play important roles. Anabolic hormones like testosterone and growth hormone promote tissue growth, while catabolic hormones promote breakdown in favor of energy.

Cortisol is a catabolic hormone released under conditions of prolonged stress to provide the energy needed to cope with the stress. If this stress persists too long, cortisol production can become disrupted, leading to decreased release, resulting in burnout (8).

Stress, Cortisol, and Recovery Time

So, it’s not surprising that muscles recover more slowly at high cortisol levels, given that anabolism is needed to create new protein in the muscles. The Texan researchers wanted to know what effect this has on the recovery time needed after strength training. They measured this by taking an inventory of the stress experienced by 31 students with experience in strength training. These 31 were selected from 1200 students because they either showed very high stress or very low stress. With these extremes, differences are easier to observe. Stress inventory was done by letting them indicate this themselves on a scale, but also by having them fill out a survey asking about certain stressful events. During a follow-up visit to the researchers, they had them do leg presses. After this, the maximum isometric strength (weight held in a static position where muscle fibers neither shorten nor lengthen), how energetic they felt, fatigue, and pain sensations were measured with a 24-hour interval. They did this for four days.

This way, the researchers could test how long the body needed to recover and generate the same amount of strength as during the leg press on the first day of training. This was then compared with the stress scores to assess any correlation. They clearly observed this correlation, even when accounting for the fitness level of the subject and training experience. Besides affecting strength, stress also had a negative impact on how energetic the subjects felt. What is noticeable, however, is that there was no correlation with perceived fatigue. Unfortunately, the research does not state how fatigue was measured. They could indicate energy levels, for example, whether they had absolutely no energy or more than ever. Common sense suggests that the lack of energy inherently implies fatigue or at least a connection between the two.

A picture is worth a thousand words, and a graph is worth a thousand tables. In the image on the right, you see three lines corresponding to the average perceived stress. The solid line is from the participants who experienced the most stress. Along the Y-axis, you see the strength they could generate during the leg press; along the X-axis, you see time in hours after the first training. Half an hour after the training, strength in all groups significantly decreased. This is logical because they intentionally underwent a heavy training session, depleting glycogen stores (stored form of carbohydrates/sugars) and damaging the muscles through training.

In the hours and days after the training, you then see significant differences in recovery. The “stressers” seem to hardly recover between days 1 and 4. You do see rapid recovery in the first few hours, but that is probably due to glycogen replenishment, like refilling the tank. Further recovery, however, needs to happen through, among other things, the creation of new protein in the muscles, which seems to be very difficult under high stress.

The researchers therefore rightly conclude that when one is stressed, this should be taken into account when determining the necessary recovery time:

Stress, whether assessed as life event stress or perceived stress, moderated the recovery trajectories of muscular function and somatic sensations in a 96-hour period after strenuous resistance exercise. Therefore, under conditions of inordinate stress, individuals may need to be more mindful about observing an appropriate length of recovery.

-Stults-Kolehmainen, University of Texas

Conclusion

Under conditions of stress, more time for recovery is needed after strength training. The researchers therefore rightly suggest that this should be taken into account when determining the necessary recovery time. Personally, I attach more importance to addressing the problem rather than considering the symptoms. If you’ve seen the above graph and see that 4 days of recovery time in cases of high stress are insufficient, you understand that a fitness schedule for 4 days or more in a week is not effective because you don’t recover sufficiently to actually grow. However, going back to one or two days a week is not an option for many because they then don’t address all muscle groups or can’t stimulate them sufficiently.

Although it’s stating the obvious, my advice is still: “Tackle the stress!”. I understand that you can’t fire your boss or just burn those bills if that’s the cause of stress. I just hope to have demonstrated the importance of actively combating stress. Instead of training four times or more a week, you might do well to replace two workouts with yoga, relaxing music, tai chi, a walk, or whatever it is that relaxes you. “But training is relaxation!” you might say. I completely agree with that. Although it’s relaxation for the mind, it’s also a heavy burden for the body that is not able to withstand it under too much stress.

References

1. Stults-Kolehmainen, Matthew A.; Bartholomew, John B.; Sinha, Rajita. Chronic Psychological Stress Impairs Recovery of Muscular Function and Somatic Sensations over a 96 Hour Period. Journal of Strength & Conditioning Research:POST ACCEPTANCE, 13 December 2013. doi: 10.1519/JSC.0000000000000335
2. Cohen, S, Kessler, RC, and Gordon, LU. Strategies for measuring stress in studies of psychiatric and physical disorders, in: Measuring Stress: A Guide for Health and Social Scientists. New York: Oxford University Press, 1995, pp 3-24.
3. Lazarus, RS and Folkman, S. Cognitive theories of stress and the issue of circularity, in: Dynamics of Stress Physiological, Psychologcal, and Social Perspectives. M Appley, R Trumbull, eds. New York: Plenum, 1986, pp 63-80.
4. Sapolsky, RM. Why Zebras Dont Get Ulcers: An updated guide to stress, stress-related diseases, and coping. New York: Owl Books, 2004, p 6.
5. McEwen, BS. Physiology and neurobiology of stress and adaptation: Central role of the brain. Physiol Rev 87: 873-904, 2007.
6. Walburn, J, Vedhara, K, Hankins, M, Rixon, L, and Weinman, J. Psychological stress and wound healing in humans: A systematic review and meta-analysis. J sychosom Res 67: 253-271, 2009.
7. Christian, LM, Graham, JE, Padgett, DA, Glaser, R, and Kiecolt-Glaser, JK. Stress and wound healing. Neuroimmunomodulation 13: 337-346, 2007.
8. Biol Psychol. 2008 Apr;78(1):104-13. doi: 10.1016/j.biopsycho.2008.01.006. Epub 2008 Feb 2. Cortisol dysregulation in school teachers in relation to burnout, vital exhaustion, and effort-reward-imbalance. Bellingrath S, Weigl T, Kudielka BM.