Strength training during reduction – essential or meaningless? Part I

There are numerous misunderstandings and false opinions circulating around the subject of strength training during reduction. They are usually spread by a sort of "experts" from local clubs who have more than 95 cm in their waist and impressive bellies. Surprising is amount of "knowledge" you can acquire listening to their pieces of advice. In this article I will explain a few basic and, yet often misinterpreted, matters connected with the role of strength training. The opinions mentioned below are in accordance with contemporary scientific knowledge, though you may come across some contradictory recommendations based on the state of knowledge of the 70's and 80's. Similarly to strength training, supplementation, cardio and information on fat burning have been different in times of Arnold from what we know today. So, if you want to get rid of fat quickly and effectively, you are welcome to read this article.

Thesis # 1: „strength training is redundant during reduction for it's cardio that burns fat”

Facts are these: every effort, both aerobic (march, light run, cycling, recreational swimming, climbing on elevation) and anaerobic (strength training, runing intervals ie. 15 seconds of sprint/15 seconds of rest repeated 10-20 times, metabolic session, martial arts training, a 400 m run – repeated 3-8 times) can contribute to fat tissue reduction. It is the intensity and its duration that produces results (and the greatest influence has a diet but it is not what this article is about).

Paradoxically, it turns out that long aerobic training (that is lasting over 40-45 minutes) may, in the long run, bring more harm than profit to sportsmen who base their fitness on physical strength and body mass. The lower intensity of a workout, the higher risk of muscle and strength loss. How is that possible if everyone recommends 45-60 minutes of aerobic on a training-free day or 15-20 minutes of cardio after a strength training?

Long and frequent cardio training effectively increases the level of cortisol, hormone which has a broad spectrum of influence on human body.

One of experiments conducted on endurance sportsmen proved that repeated aerobic exercises have significant effect on secretion of considerable amounts of cortisol. Scientists from Dresden, Germany, checked what is the influence of cardio on HPA axis (hypothalamus - pituitary - adrenal). When checking the level of corisol in a traditional way (for example in blood or urine) scientists came across many problems and results of amount of this hormone in organism refer to short periods of time and unreliable fluctuations. In order to check what are long-term changes of cortisol level, sportsmen's hair was analysed. This allowed for long lasting cortisol accumulation to be checked. Hair samples of 304 sportsmen (long-distance runners, triathlon participants and professional cyclists) and 70 people of a control group were taken. Endurance sportsmen had a significantly higher level of cortisol than the control group. Moreover, it has been proved that volume of endurance training is directly linked with high level of cortisol secretion.


Long cardio trainings caused higher cortisol secretion, which has negative influence on muscles, body mass and strength.

„What else do I need to know about cortisol?”

Cortisol is, on the one hand, a way of your body to tackle the problem of muscular inflammation. Training causes microtrauma in your muscles, and your body manages to cure itself by, for example, secretion of many substances, including cortisol. You often jog, do some spinning, work out on a treadmill? On the other hand, you should know that cortisol increases protein degradation after a training (muscle loss), increases concentration of glucose in blood (and its synthesis in liver, to simplify, from fats). It also has lipolytic properties (in a nutshell, it activates the process by alowing to use already deposited fat) - but... it turns out that cortisol contributes to deposition of the worst type of visceral fat and loss of arm and thigh muscles. What is characteristic for cortisol is that fattening up caused by this substance is localised in abdomen (waist), neck and face. Interestingly, according to S. Ambroziak, cortisol's lipolytic actions are observed in limbs. In one of tests, runners were given 1.5 grams of vitamin C seven days before a run, on the day of a run and two days after. A noticeable drop of cortisol lever was observed. The greatest antiphlogistic effect was noted just after a 90 km run. What is worth noticing, a group dosed 0,5 grams of vitamin C achieved emphatically lower effects within the context of cortisol and adenaline amount after the run. On top of that, in the group which was taking 1,5 grams of vitamin C, amounts of interleukin 10 (IL-10) and IL-1Ra were lower, which means less inflammation caused by the run.

„What about cortisol vs. strength training?”

Intensive training also causes increase of cortisol secretion (muscle inflammaton and microtrauma appears). Such work is of an interval character and unsteady structure. Similarly, metabolic training cause big variations of corisol secretion levels. Let's get back to muscles and their work, first. Cardio training engages most type I fibers (slow, endurance muscle fibers), partially type II a (mixed). In strength training the proportions are inversed: the greatest work is done by IIa fibers, it rarely employs the strongest type IIx ones. You also use various energetic systems. Oxygen proceses dominate in endurance trainings (aerobic): glucose, fatty acids. In strength training: anaerobic processes are there (glucose, phosphocreatine, ATP). However, aside from causing higher level of cortisol, strength training also leads to tremendous secretion of lactic acid, growth hormone and testosterone. These last anabolic hormones reduce the negative impact of cortisol on your body. In case of cardio, there is no adequate stimulus.

Conclusions and final recommendations:

  • Aerobic training is not essential for fat reduction. Reasonable changes in your diet, intervals and strength training turned out to be more effective for fat burning,
  • Cardio and strength training engage contrary methabolic systems in your muscles,
  • Strength training is an indispensible element of fat tissue reduction. High secretion of growth hormone and testosterone does not take place while low-intensity trainings (aerobic) but it is an integral part of interval and strength sessions,
  • The speed of fat reduction laregly depends on a diet, not training. The worse diet, the slower reduction effects,
  • The more muscles you have, the easier you will get rid of fat tissue (the more muscles you lose through cardio training, the slower the process of fat burning),
  • Strength training and cardio complement each other perfectly. Body mass and strength training contributes to less muscle inflammation (cortisol level decrease). If, for various reasons, you must do cardio, add strength training to it, too,
  • Too long and of too low intensity cardio trainings may, paradoxically, increase inflammation, destroy muscles and cause loss of power and muscle mass (cortisol increase, testosterone decrease),
  • If you can, don't exercise on gym cardio equipment – instead, choose for example outdoor training,
  • A better solution than cardio is high-intensity interval training (sprint, run, tug of weights, line climbing, jumps, metabolic training and crossfit)
  • It is worth to take cortisol lowering agents such as probiotics, witamins (ie. 1-1.5 grams of vitamin C a day)
  • Leave long-term aerobic trainings to professional endurance sportsmen. They are not muscle-strength or body mass oriented,
  • Exercising on an empty stomach, for example in the morning, is an ideal way to worse muscle inflammation. The highest concentration of cortisol in your body is between 6:00 and 8:00 am. You can arrive at conclusions on your own,
  • Moderate cardio training has its purpose. It is used to build your endurance base for interval training and as "burning after" the intervals,
  • Thanks to interval training, you can save a half of normal training time and win wonderful effects,
  • Intervals contribute to testosterone level increase, whereas cardio may cause the oposite,
  • The bigger muscle parts you use while training (either strength one or interval) the more lactic acid and growth hormone is produces, and this has an effect on fat burning,
  • Cardio has got minor impact on REE (resting energy expenditure), but strength training (such as GBC, TNT) and intervals (ie. sprint, interval running, run with weights) – has got considerable,
Sources: 1. 2. 3. “Elevated hair cortisol concentrations in endurance athletes”. Psychoneuroendocrinology. 2012 May;37(5):611-7. doi: 10.1016/j.psyneuen.2011.09.001. Epub 2011 Sep 25. Skoluda N, Dettenborn L, Stalder T, Kirschbaum C. Department of Psychology, Technical University of Dresden, Dresden, Germany. 4. “Wady, liczne, treningu aerobowego” Charles Poliquin