The Acute & 24h Effects of 3 Types of High Intensity Circuit Training on Testosterone & Cortisol in Young Trained Men.

It's obviously to have the 24h effects on testosterone and cortisol than only those measured after the workout , but can we make solid conclusions based on the additional data?

In spite of the fact that the acute testosterone and cortisol response to exercise appears to have little direct effects on the overall training outcome (Schoenfeld. 2013), acute increase in cortisol and reductions in testosterone, i.e. a decrease in the testosterone:cortisol ratio is a classic feature of overtraining and can very well blunt, if not reverse the beneficial effects of exercise on your health and body composition.

Against that background a recent experiment that was conducted by researchers from the University of Chieti-Pescara in Italy could be of great interest to everyone who is performing high intensity interval training on a regular basis. Why?

Well, in contrast to previous studies, Blasio et al. investigated both the acute and 24h effects of a high intensity interval resistance training regimen in trained young men.

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To characterize the effects on heart rate and hormonal responses the subjects, eight trained, healthy trained men (28.61 ±3.51 yrs), performed three different workouts which had the same exercises, the same load and number of repetitions for each exercise, but different exercise order, recovery and speed of execution.

• RANDOM workout: the assigned goal was to complete the assigned repetitions respecting only two duties. The first one was don’t stop until all of the repetitions were completed; the second was that there were no assigned order of execution of exercises and no assigned consecutive repetitions to complete.
  
  Participants were thus free to choose both the order of exercises and number of consecutive repetitions for each exercise (i.e. 2 repetitions of kettlebell swing, 10 repetitions of medicine ball slam, 20 repetitions of squat, 4 repetitions of spin with Bulgarian bag, etc.).
  
  No recovery period was assigned, except the time necessary to move from a station to another, and no speed of execution of exercises was assigned: participants were free to choose the preferred speed. 
• LADDER workout: respecting the following order of execution, kettlebell swing, medicine ball slam, spin with Bulgarian bag, squat, pull-up, burpee, participants had to complete the total repetitions according to a pyramidal scheme (e.g. 1st lap 10 repetitions at each exercise, 2nd lap 9 repetitions at each exercise) until the total number of repetitions of each exercise was executed.
  
  Each lap of the circuit was followed by 1 minute of recovery. No speed of execution of exercises was assigned: participants were free to choose the preferred speed. 
• AS SOON AS POSSIBLE (ASAP) workout : respecting the following order of execution, kettlebel swing, medicine ball slam, spin with Bulgarian bag, squat, pull-up, burpee, participants had to complete the total volume in six laps executed as soon as possible.
  
  During each lap participants had to complete the sixth part of total number of repetitions of each exercise without rest among exercises. Each lap of the circuit was followed by 1 minute of recovery.

Salivary samples were collected before and after each workout, at 11:00 p.m. and at 7:00 a.m. of the following day. Salive was also collected during a non-training day. Similarly, before and after the workout, plasma lactate was measured while a beat-to-beat heart rate recording was executed during each workout. Cortisol (C) and testosterone (T) were measured in salivary samples.

2h before the workouts the subjects who had to abstain from sexual intercourse, stimulants and alcohol from 2 days before to the experimental days and until 9:00 a.m. of the following day, consumed a standardized meal that was lower to 400 and consisted of 33 cl of water, 35 cl of orange juice and two 30 g energy bars (Power Sport Double Use, Enervit, Milan, Italy).

Let's look at the results

While the protocols elicited the same heart rate response (the major part of each workout was spent between 80 and 100% of maximal heart rate, confirming the high cardiovascular intensity of the workouts), they elicited different hormonal and lactate variations with the LADDER workout producing the lowest lactate increase and the RANDOM workout eliciting the highest lactate, cortisol and testosterone increases.

Figure 1: Relative changes in hormone and lactate concentration in response to the workouts (Di Blasio. 2014)

When C was considered in ratio with T no significant differences have been shown among workouts-induced variations. Results of the analysis of covariance, executed on significantly modified variables, confirmed that basal hormonal and lactate values did not influence their variations.

When they studied the effects of workouts on prolonged hormones production (i.e. until the morning following the morning, di Blasio et. al. found that observed that observed that

"C had both time (F=179.723; p < 0.001) and group × time effect (F=10.942; p < 0.001): while during non-training day there is a physiological decline of C production at 11:00 p.m., during training days its decline is not present but seems to have a continuous increase from 7:00 p.m. to 7:00 a.m." (Di Blasio. 2014)

For the testosterone production the authors found both time (F=443.340; p < 0.001) and group × time effect (F=3.254; p=0.008) even if the group × time effect seems determined by the samples collected at 7:00 p.m., so that the effects cannot be ascribed fully / exclusively to the workout.

Figure 2: 23h hormone profile after the RANDOM, LADDER, ASAP workouts on a control day (di Blasio. 2014)

What is most interesting, though, is the cortisol to testosterone ratio. It shows the greatest inter-group differences and could potentially be of great physiological relevance (Crowley. 1996). In that, the LADDER workout has the most negative effect, as it will totally blunt the natural decline of the C:T ratio at noon.

In case you're planning to incorporate circuit training into your schedule, make sure to have a huge chunk of beef after your workouts ;-) - "Post-Workout Steak "Supplementation" (135g of Lean Beef) Augments Improvements in Body Composition In Response to 8 Weeks of Circuit Resistance Training" | more

Bottom line: As usual, it is difficult to interpret the results in order to make concrete practical recommendations. The lactate and hormonal data does yet suggest that the "random" order, i.e. a training that involves a self-selected exercise order and rep speed, as well as little to no rest between exercises is the least, the ladder training, with its decreasing 10, 9, ... rep numbers and one minute rest between each lap of the curcuits is the most metabolically demanding workout.

Whether and to which extend this translates into an increased risk of overtraining, let alone increased muscle and strength gains, on the other hand, remains to be seen. In view of the overall effect on lactate levels and the C:T ratio, though, the study does suggest that you better be careful with high intensity circuit / interval resistance training sessions and give your body adequate time to rest and recover | Comment on Facebook!

References:

• Crowley, Michael A., and Kathleen S. Matt. "Hormonal regulation of skeletal muscle hypertrophy in rats: the testosterone to cortisol ratio." European journal of applied physiology and occupational physiology 73.1-2 (1996): 66-72. 
• Schoenfeld, Brad J. "Postexercise hypertrophic adaptations: a reexamination of the hormone hypothesis and its applicability to resistance training program design." The Journal of Strength & Conditioning Research 27.6 (2013): 1720-1730.