Endurance (Over-)Training - Are Even 25 Minutes Too Much for Us to Handle or is the Decrease in DHEA and Increase in Cortisol in Response to 3 Workouts / Week Irrelevant?

Can 25 minutes thrice per week really be "too much" cardio for young, healthy women or is DHEA/CORTISOL another bogus marker of overtraining? Find out in today's SuppVersity article.

If you've read the articles in the SuppVersity Athlete's Triad Series you will know that "cardio" training, and here specifically doing hours of high intensity cardio workouts will put you at a higher risk of "overtraining", i.e. training so much that (a) your progress stalls, initially, and (b) you may eventually ruin your health. Unfortunately, we have only very few reliable markers of overtraining. Markers that have previously been used to assess the effect of exercise on the nervous system is the ratio of DHEA to cortisol. Somayeh Mahdaviyan, Laleh Behboodi, and Mojtaba Ezadi from the Azad University used the same marker in their latest study (Mahdaviyan. 2015), in which they sought to determine the exercise induced changes in the DHEA to cortisol, of which Urhausen et al. (1995) previously argued that it is a better marker of exercise induced stress than the more commonly used testosterone to cortisol ratio in women.

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The subjects of the study were previously inactive healthy young women studying at the Azad University of Tehran center (20 to 28 years old, mean age: 24.50 ± 2.7 years, height 164.64 ± 5.624 cm, weight: 57.928 ± 4.921 kg and body mass index (BMI) 21.376 ± 1.031 kg per cubic meter).

Figure 1: Don't confuse overreaching (strategic short-term overtraining) with chronic overtraining - one can help you make progress, the other will stall your progress (Budgett. 1998).

The endurance training regimen the young healthy women performed was by no means crazy. Rather quite prudent, as the following remarks indicate (Mahdaviyan. 2015):

"Endurance training was consisted of 8 weeks and 3 days each week. A percentage of maximum heart rate and duration of exercise was considered as intensity and volume of training. Each run session was 35 minutes including a 5 minute warm up, 25 minutes main exercise and 5 minutes cool-down; 25 minutes of main exercise was include running on the treadmill. For first to eight weeks done with 60%, 65%, 70%, 70%, 75%, 75%, 80% and 85% of maximum of heart rate. To display the heart rate on the treadmill screen was used the belt. 

Don't be that stupid bro who falls for the industry myth of the "bad, bad cortisol"! It is not desirable or healthy to crush your cortisol levels and in fact, rather than elevated, chronically low cortisol levels are a key feature of full-blown, longstanding overtraining and a subsequent failure to lose weight and perform in your everyday live | learn more.

Each subject started and finished all activities meetings at own time, that this time were the same for all. Hormonal analysis: 48 hours before and 48 hours after training, were collected blood sample of subjects of both groups from central venous at a rate of 5 ml. It should be noted that after each session, participants were considered to drink enough fluids to compensate for lost fluid" (Maladavyan. 2015).

The statistical analysis of the results of the blood tests revealed that the cortisol levels in the exercise group were significantly increased compared with the control group (P<0.05). The ratio of DHEA to cortisol on the other hand, decreased significantly.

Figure 2: Significant changes in cortisol & DHEA; but also significant changes in body weight which are obviously what most people want to achieve by doing cardio were achieved only in the training group (Mahdaviyan. 2015).

At least in theory, this appears to indicate that any 8-week endurance training similar to the present protocol will establish a catabolic environment in the body of inactive young women. Mahdaviyan, et al. further point out that they believe that this was a results"overtraining, and besides the psychological and physiological condition" - that's a conclusion I cannot agree with. After all, any physiological adaptation in response to exercise requires stress and if doing 25 minutes of exercise thrice a week was detrimental to our health, active individuals should be unhealthier than their lazy peers.

Overall, the study results are thus not significant and they don't provide evidence not to 3x25 minutes of "cardio" per week - sorry, bros | Comment on Facebook!

This does not mean that you should not follow the following rules of thumb in order to reduce your risk that "more becomes less": (1) Increase your volume and intensity in max. 10% steps; (2) variety is not just the key to success, it's also the key to avoid overtraining - change things up regularly and periodize your workouts; (3) rest at least 24h, better 48-72h between workouts; (4) don't take exhaustion as a marker for effective workouts; (5) eat enough, even if you diet don't go past a 30-40% deficit and refeed regularly; (6) stay hydrated; (7) sleep enough (6.5-8h) and follow regular sleep pattern; (8) if you have been training hard for 6 weeks take 2 weeks off and see if you are back in (top) form; (9) if you've been chronically overtraining accept that it may take 1-3 months of at best light exercise for you to recover - don't be a fool!

References:

• Budgett, Richard. "Fatigue and underperformance in athletes: the overtraining syndrome." British journal of sports medicine 32.2 (1998): 107-110.
• Mahdaviyan, Somayeh, Laleh Behboodi, and Mojtaba Ezadi. "The Effect of Endurance Training on the Ratio of Serum Cortisol to Dehydroepiandrosterone (DHEA) in Inactive Young Women." International Journal of Basic Sciences & Applied Research. Vol., 4(1), 38-43, 2015.
• Urhausen, Axel, Holger Gabriel, and Wilfried Kindermann. "Blood hormones as markers of training stress and overtraining." Sports medicine 20.4 (1995): 251-276.