From experience and observation throughout my time at many gyms, one cannot help but take note of the popularity of the cardio machines, that is the treadmill, X trainer, bike, stepper and rower found in most gyms. Particularly during the rush hours, on busy days there may even be people cueing to use one of these machines.
Whether this popularity is due to enthusiasm for carrying out these activities for pleasure, or confidence in knowing how to use these machines as opposed to attempting to use the free weights or even the resistance machines or perhaps due to the option of plugging in the headphones and watching Friends or Deal or No Deal at the same time whilst jogging for 30 minutes to make the perceived chore of going to the gym more enjoyable will vary from person to person.
Another possibility is perhaps the feature on these machines that tells you how many calories you have burned in your session. This can be for some quite beneficial from a motivational perspective. It allows one to set themselves goals and see them through. One can say to oneself, “I am going to spend 40 minutes on the treadmill, catch up on the news and aim to burn 450 calories, I can kill two birds with one stone.” Or in the case of the bike, some I have seen reading books whilst cycling.
The counting of calories burned during an exercise on a cardio machine is not as may be perceived by many a reflection of how much fat one has burned. The body burns calories all day long, including in our sleep. The body has a number of different energy systems that utilizes carbohydrate, fat and protein to produce energy differently depending on the kind of activity we are doing and its level of intensity. No energy system acts alone and each will contribute in varying levels of degree when we are doing different exercises.
For example, the Phosphagen or Immediate Energy System comes into play during all-out exercise lasting roughly 5 to 10 seconds such as lifting a heavy weight, a 100-meter sprint, diving, jumping, sprinting up a flight of stairs, or any other activity that involves a maximal, short burst of power. Any high intensity exercise lasting longer than 10 seconds requires assistance from other sources of energy.
Table 1. Nutrient usage at different exercise intensities
| Nutrient | At Rest | Light to moderate intensity exercise | High-intensity endurance exercise | High-intensity sprint-type exercise |
| Protein | 2-5% | 2-5% | 5-8% | 2% |
| Carbohydrate | 35% | 40% | 70% | 95% |
| Fat | 60% | 55% | 15% | 3% |
Whilst there is a misconception amongst many to believe that aerobic training and particularly cardiovascular-based exercise such as running is best for burning fat and that resistance training or weight training is best for building muscle, this is quite misleading. For example, at about 25 percent of aerobic capacity (i.e., low intensity exercise), fat is the main source of fuel, but one isn’t burning a significant number of calories. If ones goal is to lose weight, the key factor is the net deficit in calories, not where the calories come from. As exercise intensity increases, the number of calories burned also increases. Therefore, while it is true that fat contributes a greater percentage of the total energy during lower intensity exercise, at higher intensity exercise, the total quantity of fat utilized may be greater for exercise performed for an equivalent period of time.
As one can see from Table 1 that the percentage of calories burned from fat will depend on the level of intensity one is working at. Some users of cardio machines are aware of interval training and therefore when running for example will work in high intensity intervals for 2 minute all out spurts where the body will shift from working from a light to moderate intensity to a high intensity sprint. Others will run continuously at a medium intensity.
One must also take into consideration other aspects of metabolism when trying to lose fat. Metabolism is largely a function of how much muscle one has. Aerobics does nothing to maintain muscle and will do nothing to contribute to raising ones metabolism at rest. One will burn calories during aerobic exercise, but will not burn any more at rest as a result of doing aerobics. If you burn a lot of calories from aerobic training, the body will adapt to aerobic exercise by slowing your metabolism and allowing your body to store more fat.
Most people in the gym using treadmills will run for a period of time that they have available to them within their working day, which could be anything from 20 minutes to an hour usually. This variable does not often change. One may set for themselves a running goal of 5km, for example. First they will aim to complete the distance and when they are fit enough to complete 5km at a set speed without stopping (often a common goal) they can then work on increasing the speed at which they complete it in. This means that calorie expenditure within that half hour will decrease as one gets fitter causing one to either have to run for longer (which one does not have the time for) or to run faster, but by running faster one will eventually cease to be working aerobically and start working an-aerobically in order to gain the same benefits that they started with.
For people like myself who wish to lose fat and not lose muscle mass and also wish to gain some muscle, high intensity endurance exercise will burn fat but also protein which will result in loss of muscle mass. If you look at long distance runners, they are very thin with low body fat but also lacking in muscle mass, unlike a short distance 100m sprinter who has a lot of muscle mass and low body fat.
When one rationalizes their activity that they are going to the gym and running or cycling frequently they see that their performance of an exercise has progressed to an extent from when they have started in so far as that they can complete a distance and not feel as tired as they first did and have lost a couple of pounds by virtue of them previously having done no exercise at all and think “I’ve been training really hard, and I am always sweating after my workout, something must be happening.” Of course something is happening, ones heart and lungs are becoming stronger. But unless one wishes to run a marathon or is solely interested increasing their cardiovascular fitness then this is not the most productive use of ones time. Most people using cardio machines also have fat loss goals. This will explain why people often quit going to the gym after a month, when at this point they have progressed as much as they can spending 40 minutes on a treadmill, have got used to it and are no longer seeing anymore fat come off, and in some cases putting some of it back on.
When it comes to non resistance training exercises that will burn more fat than running it is the kind of stuff that we would not be disciplined enough to do on our own and that personal trainers often include in your programs, those sprints up steps, the 20 burpees, skipping and squat thrusts. It’s not possible to do that kind of training whilst watching the News at the same time. Cardio machinery with TV and headphone slots with a calories burned display monitor may be a big selling point for prospective gym membership buyers, but it is he who dares to not use them and focus on the free weights and explosive anaerobic exercises that wins in the end, losing fat and becoming lean.
Alex Carson
