“The Heart is not a Machine”

In the recent years the idea of High Intensity Interval Training (HIIT) has become fashionable. Coaches, doctors and various health and fitness gurus have written books on how you can achieve the same - and more - by training four minutes a day and how bad for you prolonged endurance exercise is. As evidence the gurus quote studies on marathoners that show increases in various biochemical markers of myocardial damage. On the other spectrum of "evidence" are short term studies showing better results in terms of aerobic and anaerobic performance or fat loss. HIIT is now the rave of the Internet fitness advice, and slow jogging for half an hour three times a week is out of favor. It's all bullshit, of course. Why it is so is explained in the post that follows.

At one of the GS forums I came across a link (http://www.roller.ru/content/cat-181/article-1495.html) with the discussion of an interesting book by Victor Seluyanov. The title of the book in question is “Preparation of Middle Distance Runner”. The author is a serious PhD coach with more than 100 publications in peer reviewed journals. Mathematical modeling is one of author’s interests, and one chapter of his book is devoted to the discussion of processes that happen in the heart during training. The link refers to the discussion of the book between two commentators, a doctor and a cross-country skier, which covers many topics, such as the effect of different training regimes on different types of muscle fibers, assessing muscle composition and other complicated stuff. This post borrows the title from the part of the discussion that is dedicated to the adaptation processes in the hearts of middle runners. The text that follows is the summary of the discussion. 

What is happening to the heart during training? It is important to understand that the heart is not a mechanical machine and it is relatively easy to damage it by training incorrectly. The main effect of training on the heart is the increase in minute volume, the amount of blood the heart is able to pump in a minute. The heart gets larger, or develops hypertrophy. There are two types of cardiac hypertrophy: L-type, when the heart muscle stretches, its muscle fibers get longer and the volume of the heart increases; and D-type, when the thickness of the heart wall increases, therefore increasing the strength of contraction.

In order to increase the volume of the heart they use training at heart rates corresponding to the maximal stroke volume. Just as the reminder, stroke volume is the volume of blood expelled by the heart during one contraction. Usually stroke volume sharply increases at HR of 100/min, at 120 increases more and in some individuals still increases until HR of 150. Prolonged training at maximal stroke volume is, figuratively speaking, “stretching exercise” for the heart. Muscles pump the blood, and the heart get stretched by the increased flow. As the consequence the heart dilates. It is possible to double its size, and 30-40% is almost a guarantee. That’s what is meant by coaches when they say “building the base”; it is, in fact, stretching of the heart.
Working the heart at heart rates close to maximal - 180/min and higher - causes D-type hypertrophy of the heart muscle. The heart is the muscle and therefore needs the blood in order to contract. The blood is delivered to it mostly during diastole, or relaxation phase. When working at maximal heart rate, the heart does not fully relax, and the blood supply is impaired to some degree. What follows is the accumulation of acidic substances leading to acidosis which, in turn, stimulates growth of the heart muscle. This is typical for interval training, the rave of the fitness crowd in recent years. The problem starts when this kind of training is done too often. If the heart does not relax, its blood supply is impaired, the delivery of oxygen becomes inadequate and anaerobic glycolysis starts. As the results lactic acid is produced and leads to the acidosis inside the cell. If it lasts long enough, some cellular structures die. And if it lasts some more, the whole myocardiocytes – heart muscle cells – can die. This is microinfarction. If the training of this intensity is repeated again and again, more cells die and are replaced with the connective tissue which, in turn, does not distend well during diastole and does not properly conduct electric impulses necessary for adequate cardiac contraction. Apparently this has been confirmed by autopsies of athletes who suddenly died during physical activity.

That is why it is important to first build the base – dilate the heart – and only then increase intensity. Working at heart rates close to maximal must be introduced gradually and done infrequently, especially at the early stages of training. This also brings us to the topic of recovery and frequency of training. If your muscles are sore after a workout, you take a day or two off and allow them to recover, to heal. Why should the heart be different? Adaptation takes days and the heart muscle needs rest in order for these processes to take place.

All of this is directly applicable to girevoy sport. This sport is primarily an endurance activity with the intensity thrown on top of it, and its effects are very demanding, both in terms of the load and the ability to recover. Both snatches and jerks done at high tempo for prolonged period of time shoot the heart rate close to the maximum. I am not aware of any studies on the volume of the heart in gireviks, but would expect them to have hypertrophy of various degrees. Virtually all Russian GS coaches I came across on the Net recommend regular jogging or any other kind of aerobic activity: swimming, cycling, playing soccer etc. One girevik I have been communicating with on the Net once suggested that monitoring the heart rate may be useful in order to gauge the intensity. Taking into account the discussion above it seems like a good idea. For some of us five minute set of 2 x 24 kg jerks is no big deal, whereas for some (myself including) it is, and heart rate can give an indication of the relative intensity. There are strapless heart rate monitors available, which makes it easier to use them during timed GS sets.

Having said that, however, the approach to training should be simple and one mustn't get caught in the minutae of heart rate monitoring. The principles of aerobic training are simple. First, start from building the aerobic base by going for easy longish runs. Second, do not rush into the heroic intensities. Third, don't push yourself to exhaustion every training session; at the end of the day it may be dangerous for your health.