I think It's pretty safe to say that if you're a fan (or a member) or Training4Muscles then you're taking your training pretty seriously. This article wont be of much interest to all those people who "head down the gym" to check out chicks (or guys!), give themselves something to tell their mates or to read a book (how do people do that in the gym??!!). This is about what happens to your body when you exercise on a regular basis.....

Changes occur to the muscle fibres that you employ during training. That sounds like an obvious thing to say, but take a second to think about it.... if you're working hard to isolate specific muscles, you're missing out on the work you do to the stabalisers, neutralises, antagonist etc. This suggests that "functional" training can be very beneficial if you have an end goal in mind for your training; you get what you train for. Anyhow, this is called "Specificity" when related to training.

There are various changes that your body will undergo when undergoing an (appropriate) CV training regime. When I say appropriate, that means that you are pushing yourself hard enough that your body will undergo the "Training effect" (more about that later but essentially the ACSM suggests a minimum threshold of intensity/duration/frequency in order to develop your fitness. Walking 5 minutes a day just wont cut it!).

Ventilation

With correct training effect, training will:

• Increase the volume of air per breath you take (the "tidal volume").
• Enhance the efficiency of your breathing (i.e. you will need fewer breaths to do the same amount of work).
• Increase the length of time it takes for you to get fatigued and/or distressed due to elevated respiratory rate.
• Improve the transfer of oxygen over the surface area of the lungs, allowing more time for oxygen to enter the blood (creating oxyhaemoglobin).

Blood Volume

A very important physiological effect occurs when you undergo CV training in the long term. Not only does the volume of blood that is strored and utilised by your body increase but more importantly, the haemoglobin density increases. Haemoglobin is contained in the red blood cells within your blood stream and importantly are the carriers of oxyygen (they become oxyhaemoglobin) to you muscles. Quite obviously the more oxygen you can get to your muscles, the better respiratory effect you are going to get and the better you will perform. (A good example of this effect is when cheating athletes use blood doping to perform better).

Stroke Volume

Hopefully you are aware that the heart is composed of a number of chambers. Endurance training has the effect of increasing the size of the left ventricle during the filling phase (the diastole). This increase in size comes about with little change in the thickness of the heart muscle (it is  referred to as an increased "Left Ventricular End Diastolic Volume" or LVEDV for short). The resulting "oversized" heart is able to pump more blood around the body both at rest and during exercise, giving the opportunity for your heart to beat less times (your blood transfer capacity is equel to stroke volume multiplied by heart rate).

Redistribution of blood

Your body is really intelligent (even if your brain sometimes isn't) and it understands the importance of keeping you performing at your peak. Your body learns through exercise that it is more efficient to divert blood away from the less active tissue and to muscles where it can do some real good! Long term adaptations cause your body to divert blood to active muscle, heart (for pumping) and eventually skin to help you cool yourself (thermoregulation). This can lead to an increase in the blood flow to the muscles doing the work of 20 times or more even though the output of your heart (cardiac output) increases by only 3 to 5 times.

Capillaries

Your capilliaries (tiny blood vessels) will increase as a result of prolonged exercise. This is beneficial to your body because it facilitates better diffusion of blood, and hence oxygen into and waste out of, the muscles.

Endocrine system adaptations

The endocrine system is a system of glands, each of which secretes a type of hormone into the bloodstream to regulate the body. The endocrine system is an information signal system like the nervous system. This undergoes adaptations to exercise to enhance its performance.

Changes to hormonal response

The long term effects of training can be seen in adaptations by your body to hormonal secretions and response. Your body learns to fine tune its emission and response to hormones and this is important because there are a great many hormones that are responsible for the production of energy.

Fat mobilisation

Training will improve the oxidative ability of muscle (its ability to use oxygen) and this lessens the build up of lactic acid in the blood stream. Rising lactic acid levels in the blood is known to block the effects of epinephrine (a hormone responsible for the mobilisation of fat).

Body composition.

Most obviously, if you burn calories that you do not replace by fully (or over) compensating in your diet, you will reduce the amount of adipose tissue (body fat) carried on your body. For example, if you create a 1700 calorie deficit per week, that's about 1/2kg fat per week you will loose.

Bone density

Moderate activity levels have been shown to lead to denser bones which provide a stronger structure for your body to use in its activities. This is a distinct advantage in the fight against osteoporosis. This effect can be counteracted by over training, excessive weight loss or menstrual irregularities as these can cause early onset osteoporosis.

Tendons and ligaments

Connective tissue in your body (such as ligaments and tendons) can be strengthened by moderate exercise. Make sure that the increase in workload is gradual so that the connective tissue slowly becomes used to the new levels of stress and do not get damaged in the process!

These are really the main LONG TERM adaptations to cardio exercise but lets not forget the short term adaptations! Those beautiful endorphines, the raised heart rate, the focus, the feeling of looking ace. There are a million and one reasons to give cardio a go, so get out there and get going!

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