Add Two Pounds of Lean Mass in Three Weeks W HIIT HIIT Sprint Training Builds Muscle Anaerobic Power While Reducing the Exercise Induced GH Response by 64

HIIT - A GH diminishing mass builder?

I know it sounds contradictory, at first. If you take into considerations that previous studies show that the post-exercise increase in growth (and other) hormones does not correlate with the beneficial adaptational effects of exercise, its actually no longer that surprising that researchers from the Department of Exercise Physiology at the Winston-Salem State University found that "[o]ne week of HIT significantly decreased GH release, with a simultaneous significant increase in anaerobic power and lean body mass of the lower extremities." (Ritsche. 2014)

In their latest paper which appeared in the December edition of the Journal of Exercise Physiology Kevin Ritsche, Jason Smith, Paul Mellick, and Laurie Wideman report the results of a recent experiment in the course of which 19 recreationally active male subjects (24.9 ± 3.9 yrs) completed a one-week high intensity interval training.

You can learn more about HIIT at the SuppVersity

Never Train To Burn Calories!

Tabata = 14.2kcal /min ≠ Fat Loss

30s Intervals + 2:1 Work/Rec.

Making HIIT a Hit Part I/II

Making HIIT a Hit Part II/II

HIIT Aint For Everyone

The training protocol used in the study was based on similar high-intensity protocols published by Burgomaster et al. (2005) and Gibala et al. (2006) and began 24 hrs after the completion of a pre-test that was designed to measure the baseline fitness, body fat and lean body mass (by DEXA), as well as the acute GH response to high intensity exercise in the 19 young subjects.

The training protocol consisted of 4 to 6 repetitions of 30-sec maximal sprints and was performed three times per week for 3 weeks. One day of rest intervened each training session.

"The first 3 training sessions consisted of four 30-sec repetitions at 7.5% body mass with 4 min of active recovery at 50 W between each repetition. Training sessions 4 to 6 (wk 2) consisted of 5 repetitions, and sessions 7 to 9 (wk 3) consisted of six 30-sec maximal repetitions. During each repetition, each subject was encouraged verbally to provide maximal effort" (Ritsche. 2014).

At the end of each week, 48 hrs after the third training session for the week, subjects completed the acute sprint test protocol outlined previously (including blood draws).

Figure 1: Changes in body composition in response to the 3-week hiit-training protocol. the percentages above the bars indicate the relative difference between pre- and post-value. The light bars tell you that the corresponding changes were not statistically significant (Ritsche. 2014).

At least 48 hrs after the final blood profile, a post-training DXA scan was completed as outlined previously.

Figure 2: (a) Peak power; (b) peak power-corrected for subjects’ body mass; and (c) fatigue index during each 30-sec maximal cycle ergometer acute sprint (as) before and after 3 wks of hit; and (d) total combined workload of every sprint during each training week (Ritsche. 2014)

As you can see in Figure 1, the DXA-scans revealed significant increases in total and leg lean mass, albeit only non-significant reductions in body fat - changes which went hand in hand with a profound increase in exercise performance (see Figure 2) and a significant reduction of the initially observed post-exercise growth hormone spikes (see Figure 3).

Figure 3: Peak growth hormone concentrations after the workouts during the pre-test and after 1, 2 & 3 weeks of training; %-ages indicate difference to pre-value (Ritsche. 2014).

Bottom line: If you take into consideration that there is a close association between the post-workout growth hormone release and the relative exercise intensity - i.e. relative to ones individual fitness level and the corresponding demands of the exercise - the amelioration of the growth hormone response could be a consequence of the adaptation process that occurred in the course of the three week intervention.

It is thus not necessarily a bad thing and does therefore not stand in contrast to the adaptational response Ritsche et al. describe in their latest paper. If you take another look at Figure 3 and compare the GH response to the adaptations in Figure 2, it rather indicates that the subjects got used to the exercise | Comment on Facebook!

References:

• Burgomaster, Kirsten A., et al. "Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans." Journal of applied physiology 98.6 (2005): 1985-1990.
• Gibala, Martin J., et al. "Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance." The Journal of physiology 575.3 (2006): 901-911.
• Ritsche, Kevin, et al. "Acute Exercise-Induced Growth Hormone is Attenuated in Response to Short-Term, High-Intensity Exercise Training." Journal of Exercise Physiology (2014).