This article hopes to explain some of the more commonly spoken about, but less commonly (properly) understood terms in the health and fitness industry. Below you will find basic explanations for terms and concepts that are fairly complex in nature. You will find that there are numerous misconceptions ‘out there’ that need rectification! Enjoy.

What is
VO2 Max?

VO2 max is the maximum capacity of an individual’s body to transport and use oxygen during exercise, which reflects the physical fitness of the individual. The name is derived from V – volume per time, O2 – oxygen, max – maximum. VO2 Max is most often expressed as a relative rate in millilitres of oxygen per kilogram of bodyweight per minute (ml/kg/min).

The VO2 Max figure has been used as a yard-stick of sorts over the years to predict the potential and capacity of an individual to take part or compete in endurance sports, but factors such as economy, muscular oxygen requirements and the ability of an athlete to operate at their VO2 Max (fatigue resistance) also play a role. Top-level elite athletes typically boast VO2 Max figures of 70ml/kg/min and above (Lance Armstrong was measured at 85ml/kg/min and Nordic skiers have been measured above 90ml/kg/min). A typical value for an active male university student might be 44-51ml/kg/min.

How does it Work?

VO2 Max may only be measured accurately by a qualified sports scientist, according to a strict protocol, with specialized equipment. The test is a maximal test which puts (eventually) maximum physical stress on the individual. Because of the limitations of the equipment, the test is most commonly done on either a treadmill or stationary bicycle. In the test, resistance is gradually increased while a fitted mask (over nose and mouth, or with nose peg) measures the relationship between carbon dioxide and oxygen of the inhaled and exhaled air. VO2 Max is reached when oxygen consumption remains at a steady state despite the fact that there is an increase in workload.

What does it mean for me?

Having a low VO2 Max does not necessarily preclude you from competing at a high level sportingly, but what IS clear is that top athletes do certainly share this common denominator to a large extent. In untrained individuals it is possible with training to increase VO2 Max by as much as 10%, but in trained individuals this figures falls into the low single digits. Improvements in VO2 Max are very incremental and usually take place over a period of years.

What is the Body Mass Index (BMI)?

The body mass index (BMI), or Quetelet index, is a measurement for human body fat based on an individual’s weight and height. It is commonly used as a general measure of an individual’s health and wellbeing. The BMI was never intended to represent a stringent scientific measure of body fat or health, though. What the BMI does do is classify inactive, sedentary individuals of average body composition along a spectrum of sorts so that general observations and comparisons may be made. BMI is calculated by dividing mass (kg) by height squared (m2):

How does it work?

The BMI continuum is as follows:

BMI (km/m2) Category
30 and above Obese
25-29.9 Overweight
18.5-24.9 Healthy range
Below 18.5 Underweight

What does it mean for me?

Depending on your activity level, BMI may or may not be a significant measure for you. Two individuals may present the same BMI, but the one may be very muscular, while the other may simply be fat –BMI does not take into account body composition. If you are an active individual who does regular exercise, BMI may not be that important a measure. If however you are a sedentary person, living a sedentary life with little exercise, BMI will be a good indicator of where you are, and (more importantly) where you need to be.

It is important to remember that the BMI is not the last word in determining health and ideal weight, but is used best when applied in an indicative manner.

What is the Basal Metabolic Rate (BMR)?

Basal Metabolic Rate (BMR) is the amount of daily energy expended by living organisms at rest. Rest is defined as existing in a neutral environment while in the post-absorptive state (i.e. an empty stomach, as the digestion of food alters BMR). The release of energy in this state is sufficient only for the functioning of the nervous system, the heart, lungs, vital organs, kidneys, liver, intestines, sex organs, muscles, and skin.

How does it work?

BMR is the number of calories your body burns at rest to maintain normal body functions. It is the amount of calories per day your body burns, regardless of exercise. It changes with age, weight, height, gender, diet and exercise habits. The greater your percentage of musculature the higher your BMR, as muscles require more ‘fuel’ to maintain.

What does it mean for me?

If you want to lose weight you need to increase your BMR! The best way to increase BMR is through regular exercise. Regular exercise will combat the natural decline in muscle mass that accompanies aging. An increase in BMR may also be achieved through diet. Eliminating a few items from your diet can assist in enhancing your BMR (here are a few): Saturated fats, hydrogenated oil, fried foods, sugary products. Of course this list is by no means exhaustive.

Heart rate and You

Resting heart rate (RHR) is the number of beats that your heart beats in one minute (BPM) when you are at complete rest (lying down without having exerted yourself recently. Your RHR indicates your fitness at a basic level. The more well-conditioned your body, the less effort and fewer beats per minute it takes your heart to pump blood to your body at rest. Your heart will typically beat over 3 billion times in your lifetime, and pump over 212 million litres of blood. Resting HR for normal sedentary individuals may range between 60-80 BPM. A well trained athlete might have a RHR of below 60, while elite athletes normally have a RHR below 45 or 40BPM. The great Spanish cyclist Miguel Indurain’s RHR was 28BPM.

Monitoring your RHR can prove useful for determining how your body is dealing with a training program –an elevated RHR may indicate over-training or possibly even indicate impending illness. It is a good idea to check your RHR every morning when you wake and ‘get to know yourself’ a little better. RHR is also used in formulas that determine training zones (either manually calculated or done by an HR monitor). The Karvonen method is one of the most popular formulas to calculate approximate HR and training zones (more precise zones may only be determined through a Lactate Threshold test by a qualified Sports Scientist). The reason that the Karvonen method is inaccurate is that it’s starting point is inaccurate: It determines maximum HR through simply subtracting the person’s age from 220. Doing this does give one a ‘ball-park’ figure though –and so is suitable for most individuals.

The Karvonen method:

220 – age = MHR (maximum heart rate)
THR (target HR) = (MHR – RHR) x % intensity + RHR

Age: 29
Resting HR: 73
Max HR: 220 – 29 = 191BPM

50% intensity: 191BPM – 73BPM = 118BPM
118BPM x 0.50 = 59
59 + 73 = 132BPM

Therefore 50% intensity is predicted at 132BPM.

This method is used by many recreational and non-elite (but serious) athletes, and is certainly a good starting point.

Calories and Kilojoules

A Calorie (usually referred to as kCal –for our purposes the same thing) is equal to 4.184 kilojoules (kJ). Simply put, a calorie is a unit of energy. Every person’s energy requirements are different, dependent on a range of factors including (but not limited to): BMR, muscle mass, physical activity, gender. Most packaged food in South Africa carries a declaration of how much energy that food contains, but this is usually denoted in kilojoules (kJ). In order to convert to Calories, simply divide by 4.184.

How does it work?

So, how many Calories should you be consuming in a day? Once again, this figure may vary widely due to similar factors as mentioned above: BMR, muscle mass, activity level, gender. As a general guideline or starting point though, recommended daily Calorie intake for sedentary individuals is 2000.

What does it mean for me?

Try not to get caught up in the details! Remember that in order to lose weight you need to create a Calorie deficit -to gain weight, the opposite. Also keep in mind that even though a food may have a low Calorie count/value, it might not have an amazing nutritional value. There is much more to food than Calorie counting!

It’s critical to keep in mind that although drastically reducing your Calories in a short space of time may initially result in dramatic weight loss, the body cannot continue along such a restrictive path, particularly if the individual is consuming below their BMR. Eating later to make up for those ‘lost’ Calories often results in gaining back the weight lost, plus extra. In addition, if you force your body to restrict Calories for a long time, your metabolism will slow down to compensate—and so slow down and/or stop weight loss.

What (exactly) is resistance training?

Resistance training is a type of training during which an individual performs a specific technique against an opposing force –most commonly a weight.

How does it work?

Simply, through muscle contractions! Possible muscle contraction types during this kind of training include:

Isotonic –involves dynamic muscle movement, include Concentric and Eccentric contractions
Concentric: Positive contraction, muscle exerts force, shortens and overcomes resistance
Eccentric: Negative contraction, muscle exerts force, lengthens and is overcome by resistance

Isometric –Muscle exerts force, but does not change in length, the tension developed by the muscle is equal to load against which it is acting
Isokinetic –a controlled reaction where force is maintained by varying the resistance e.g. Cybex machines (very expensive, mostly used by Physiotherapists and Biokineticists)

What does it mean for me?

Resistance training can result in a slowing of the natural tendency to lose muscle mass with age, and therefore minimize injuries through the stabilization of critical zones. In addition, correctly prescribed and practiced resistance training has been shown to improve the conditions of those suffering from high blood pressure and diabetes. Benefits for women and the aged are significant as this kind of training has a positive effect on bone density due to its weight bearing nature.

What is interval training?

Interval training is a type of endurance training during which bursts of speed are alternated with periods of recovery in a controlled manner. These controlled changes in intensity are predetermined and often regulated by heart rate zones. The intensity phases of interval training are usually performed at speeds that exceed goal race-pace. This can be a hazardous form of training if done incorrectly or irresponsibly because injury or overtraining may easily present itself.

How does it work?

Research has indicated that interval training may have a similar or greater fitness benefit than a longer session of continuous moderate intensity. In addition, this form of training may also serve to enhance fat loss because of the metabolism boosting effects. Finally, interval training also ‘teaches’ and conditions the body to have a higher tolerance for lactate –that’s the burn in your muscles!

What does it mean for me?

Use interval training to sharpen up before a goal race, or to ‘surprise’ your body with a new form of training. Interval training will make you a better all-round athlete (whatever your sport is –physiology is physiology). Don’t do more than one hard interval session per week though, and start off cautiously as it is easy to injure oneself if approached in the wrong way.

Information proudly brought to you by:

Peter Swanepoel

Peter Swanepoel is a fitness fanatic whose achievements include completion of more than 15 marathons, the Panorama Cycle Tour, a three day summit of Kilimanjaro, the Two Oceans Ultra, Ironman, the Comrades Marathon and numerous half iron-distance triathlons in both South Africa and the UK. His major interests include cycling, running, long-distance triathlon, as well as core strength conditioning. He holds a Masters Degree in International relations but has an infinite passion for fitness and health. He is also a certified Personal Fitness Trainer and course coordinator with the Institute of Fitness Professionals. He may be contacted at

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