Your guide to aerobic fitness

The term “aerobics” has been coined since Jane Fonda’s dance-exercise videos hit the shelves in the 1980s. Today, “aerobics” means much more than vigorous dance moves, and millions of people around the world do some kind of cardiovascular activity every day to lose weight, decrease their body fat and improve their general fitness and health.

Research has shown conclusively that a minimum of 20 minutes of aerobic exercise, done 3–5 times a week at 55 per cent to 65 per cent of maximal heart rate, significantly reduces the risk of suffering from the myriad forms of cardiovascular diseases that include high blood pressure, high cholesterol, arteriosclerosis, stroke and coronary heart disease.

What is aerobic exercise?

Any activity that is continuous and rhythmic in nature utilises lots of oxygen through your lungs and uses your heart and blood vessels to pump blood around the body is considered aerobic. Aerobic fitness is also referred to as cardiovascular fitness.

Aerobic activities also tend to exercise your major muscles groups (especially your legs), as in walking, hiking, jogging, running, swimming, deep-water running, cycling, aerobic dance, stair climbing, skating, cross-country skiing, snowshoeing and rowing. Certain fitness machines at your local fitness club — the elliptical trainer, Stairmaster and treadmill — also mimic these movements and get much the same results.

Aerobic benefits

Many marvellous physical adaptations take place as we improve our aerobic fitness. Your muscles store more glycogen and thus have a greater fuel reserve for when you are physically active and more efficient with your use of carbohydrates and fats as fuel. Your muscle tissue becomes stronger and contracts faster.

Increased capillary beds deliver more oxygenated blood to your working muscles, and increased oxygen uptake enables you to distribute more oxygen. The combined effect of these adaptations enables you to resist fatigue longer. For women, especially, but also for men, impact-related aerobic activities like running, walking, hiking and jogging help maintain bone density.

In addition to these significant benefits, a large number of well-documented holistic health benefits of being aerobically fit also accrue.

The mental and psychological benefits of being aerobically fit have been shown through research studies. People who exercise function better mentally than non-exercisers — we can concentrate better and focus more intently on our tasks. Aerobic exercisers are also more relaxed and better able to deal with stress and have lower anxiety levels.

If done correctly, aerobic activity also helps strengthen our immune systems. Several dozen studies have shown that people who exercise at a moderate level experience fewer upper respiratory tract infections such as colds and flu.

How do we get aerobically fit?

To develop this important aspect of conditioning you can choose your favourite aerobic activities from the list above and spread them out through the week.

Your goal is to do three to five cardiovascular workouts each week, varying in length from 30 to 60 minutes at a heart rate level somewhere between 55 per cent and 80 per cent of your estimated maximal heart rate.

If you are starting from scratch, start at the lower end of the heart rate range — somewhere around 55–65 per cent of your maximal heart rate — and start with lower-intensity exercise such as walking, then progress to jogging for short periods of time (say, 1–3 minutes), with walking for recovery. If you are already quite fit, you should be working out at 65–75 per cent of your maximal heart rate.

Cross training

About 50 per cent of people who start a fitness program do not last more than three months. To maximise your chances of staying with your aerobic program, preventing boredom and reducing your chances of getting injured, you might consider cross training.

Cross training refers to doing a variety of aerobic training activities such as the ones listed above. If you were to take up jogging for aerobics, its repetitive movement can overwork the same muscles and joints, leading to injuries. Cross training will establish symmetry between your muscle groups and reduce your chances of injury.

By doing other endurance workouts of low-impact or low-weight-bearing aerobic activities such as cycling, stair climbing, swimming, deep-water running or using the elliptical trainer, you get an “active rest”, with virtually no stress on your joints. Here are a few of the more common cross-training activities and some advice on how to do them.


Cycling can be done slowly for a longer period of time (20-60 minutes) or at a fast cadence—similar to your running cadence with the resistance set to one you can handle for intense five- to 20-minute workouts. Make sure you are correctly aligned on the stationary bike. Adjust the seat height so your legs are almost straight at the furthest point of extension while cycling. See the article on cycling in this issue for a detailed guide to doing this excellent exercise in the way that best suits you.

Deep-water running (aka aquarunning)

Running in place is done with a life preserver or special belt or vest that helps keep you afloat. A recent study found that runners who did deep-water running for six weeks retained their racing times.

Stair stepping

Use the stair machine for a no-impact workout. One study found people who did stair-climbing workouts for nine weeks improved their running performances. This is not surprising, as this mimics uphill walking or jogging, which consistently rates near the top in terms of methods to improve your body’s oxygen-processing abilities.

Elliptical fitness trainers

The elliptical or oval movement can be used backwards or forwards, providing the opposing muscle groups some good balance in the workout. It works the gluteals and hamstrings, two important muscle groups for aerobic workouts.

Interval training

Interval training is an extremely potent training technique that will improve your endurance very quickly. It can be used for swimming, running and cycling workouts, or for any other aerobic activity, with a few minor adjustments.

Defined as “repeated bouts of high-intensity activity, each followed by a limited rest period”, interval training involves running, swimming or cycling a short distance, repeatedly, at a speed that is always greater than could be sustained continuously for your full training session.

In other words, you swim, run or cycle shorter bursts faster than you would normally work out, with slower recovery intervals (or even rest) between these fast bursts — which is where we derive the term “intervals”.

Using the slower recovery interval periods, we eventually adapt to sustaining the higher workload for a longer period. By manipulating the length and speed of the recovery interval, you create the desired training effect, which is short recovery intervals that create an oxygen debt, enabling you to tolerate more lactic acid so you are better prepared for endurance sports events of all types.

Guidelines for successful interval training

  • It’s critical that you recover completely between interval workouts so your energy reserves are replenished and your muscle tissue has time to recover and rebuild.
  • Don’t do too many fast interval bursts in each workout. Guidelines follow.
  • Experiment with adjusting your recovery interval distance to get the desired training effect. You should be able to complete your workout feeling like it was a challenge but attainable.
  • Interval workouts should not become the focal point of your weekly training program — avoid becoming over-competitive with yourself and obsessing over your interval workouts.
  • Establish your limitations with all of the above by trial and error.
  • Most importantly, you must have an adequate aerobic conditioning base before you attempt interval training, because it’s done at such a high intensity. We recommend 8–10 weeks of continuous aerobic cross-training to prepare you for the rigours of interval training.



Figuring out the details of your interval training workouts can be tricky; you’ll need to use the acronym DIRT to help, where…

D = Distance of each fast burst

I = Interval or length of recovery (jog, walk, swim or cycle) between fast bursts

R = Repetitions. How many fast bursts you do in one session

T = Time for each fast burst

This is an especially appropriate acronym as you’ll feel like dirt if you miscalculate any of these factors.


D = Distance: the length of your interval bursts

The fast bursts in an interval workout need to be long enough to dip into the aerobic system; that is, they should be 3–10 minutes long.

The precise nature of the distances and times means interval training is best done on the 400-metre track for runners or in a swimming pool for swimmers. How far should you be running in your fast bursts? Distances that stress the aerobic system include 800m (2 laps), 1200m (3 laps) and even 1600m, although shorter interval workouts are also common over distances like 200 metres or 400 metres.

As an example of how to do interval training, here’s some advice for runners about performing interval training sessions.

I = Interval: what to do in the recovery intervals

Walking or jogging, or a combination, is recommended in the interval between fast bursts. Your first goal is to adapt to the interval workouts by attaining the maximum number of repetitions over these distances. Then, for continued improvement, speed up the fast burst or decrease the recovery interval between them.

R = Repetitions: how many fast bursts should you do in an interval workout?

The cumulative distance of the fast bursts in your interval workouts should add up to 1.0 to 1.5 miles for beginners. Running more than this significantly increases your chances of injury, while incurring diminishing benefits.

T = Time: how to estimate the speed of your fast interval bursts

The longer the fast bursts, the slower they need to be because of our limited ability to supply oxygen to the working muscles and to disperse fatiguing byproducts, such as lactic acid, as they build up.

Suggested track running interval workouts for beginners

Distance of fast burst Number of repetitions Length of recovery interval Recovery mode
100 metres 8–16 200 metres Walk/jog
200 metres 6–14 200 metres Walk/jog
400 metres 4–8 400 metres, then reduce to 200 metres Walk/jog


Your interval workout should not be so exhausting you cannot recover for the next day’s training: a slow recovery jog on a soft surface for runners; a short, slow swim for swimmers; or a short, slow indoor cycling session for cyclists. If you are too stiff and sore the day following an interval workout, it’s OK to have a rest day.

Due to the high risk of illness or injury from interval training, it’s critical that you adapt to your interval workouts rather than let them flatten you. Allow at least two to three days between these high-intensity workouts and, if you’re over 30 years old, one interval workout a week is sufficient. Your muscles, tendons, ligaments and connective tissues need much longer to recover past this age, as they lose their elasticity and resilience.

If you’re under 30, two interval workouts a week are possible. You’ll find out very quickly if you’re not recovering properly because you’ll still be sore two days later.

If you are running, swimming or cycling faster than your previous times for two to three consecutive workouts, it’s time to speed up your pace. When you can comfortably perform the workout, it’s time to increase the pace or decrease the recovery interval. Your heart rate (taken for one minute) immediately after finishing the last repetition should drop over the weeks. This is also a sign your cardiovascular system is ready to handle more.

We are all different and no two people will respond to an interval workout in the same way. Thus, avoid competing with others in your workout to reduce your risk of injury. Countless runners get injured from thrashing themselves in interval workouts against faster teammates.

Interval training variations

Another type of interval running you can do is fartlek (a Swedish word meaning “speedplay”). Here you run hard through a park or woods for a certain period of time (for example, 1–5 minutes), then jog to recover, then another fast burst and so on. This type of training provides a break from the regimentation of track intervals and gets you outdoors to enjoy nature.


Achieving your best aerobic fitness

When you take up an aerobic fitness program, you walk a fine line. If you overdo things for more than a few days, you run the risk of exhaustion, illness, injury or burnout, all symptoms of overtraining. Here’s some advice to help you plan ahead to avoid these potential problems.

Warm up before you exercise

A good warm-up is important before your aerobic workouts to prepare your body for the workout and reduce your chance of injury. Your warm-up does not need to be long or intense — 5–10 minutes of slow cycling or elliptical training followed by 4–6 easy stretches, held for 10–20 seconds will suffice.

Cool down after your workout

Likewise, for good recovery, a 15-minute jog and stretching to cool down afterwards will help disperse metabolic waste products that have built up, reducing your muscle soreness the next day.

Using “periodisation”

You can improve your fitness and avoid injury using a training technique called “periodisation”. It consists of varying the length of your workouts from day to day and week to week.

If you are to continue to improve, your training program must be varied. Our bodies adapt to the demands we place on them in training but if we continue to do the same training day after day, our bodies become comfortable with this and stop adapting, and our aerobic fitness stops improving.

Likewise, if we do not program some form of rest or recovery into our training programs we’re likely to experience muscular soreness, boredom, injury, or sickness, so vary the length of your daily aerobic workout. If you increase the length of your daily aerobic workout sessions for two to three weeks, you should be able to tolerate this well if you are healthy. But, then, back off to an easier week of reduced workouts and lower intensity every third or fourth week to allow yourself to adapt and recover.

The role of sleep

Despite their extraordinary dedication, most exercisers grossly neglect an aspect of training and recovery that would seem to be common sense: sleep. Getting adequate sleep is one component of the training and recovery cycle that is readily correctible. In fact, it’s indispensable.

One of the fundamental rules of recovery is getting enough sleep to allow the body to repair itself. Most adults require 7.5–8 hours of sleep each night, although some people need more and others less.

Antioxidant support

The downside to strenuous aerobic activity is the increased stress on your body’s cells caused by the huge amount of oxygen you process while running. This process, called oxidation, damages the muscle cells’ membranes, internal structure and organelles, impairing their function. The result: muscle soreness and inflammation, and fatigue — all done by nasty little molecules called free radicals.

Antioxidants, produced naturally in the body or obtained from your food, block most free-radical reactions. Evidence exists that certain antioxidant supplements reduce free-radical damage in runners. One study found that five months of vitamin E supplementation in racing cyclists reduced markers of oxidative stress induced by extreme endurance exercise.

Vitamins assist in growth, repair of tissue damage and disarming free-radical damage from stressful environments such as pollution and extreme cold. A strong case can be presented in favour of antioxidant vitamins being taken to hasten recovery of damaged muscle and connective tissue, free-radical damage, immune system suppression and oxidative stress caused by exercise. See the article on supplements to support exercise in this issue for more detailed information.

The nice part of recovery

Taking a sauna is believed to have some recuperative effects for your body. One study by Dr Herbert DeVries at the University of Southern California found the heat of a sauna relaxes muscles.

Massage is another pleasant way to help your body recover from aerobic exercise. Benefits of massage therapy include healing damage muscle tissue, improving blood flow to the legs, relaxation of muscles, enhanced nutrient and oxygen delivery to the muscles, increased removal of lactic acid, improved flexibility of the muscle and connective tissues, breaking-down of scar tissue and a kind of pre-emptive therapy on “knotty” areas that are tightening up and that could become injured.

Looking after your feet

Running on grass, sawdust, treadmills or dirt surfaces significantly reduces landing shock when you run. Running on grassed areas is ideal. Concrete should be avoided at all costs and asphalt is only a slightly better running surface, so minimise this.

Treat yourself to a new pair of running shoes. While you’re out pounding the road it’s not the lightness of the running shoe that is important; it’s what is between you and the road. Chances are that your current pair has lost its cushioning — the ethyl vinyl acetate (EVA) material in running shoe midsoles breaks down within a few months and somewhere around 600–800 miles of running.

General warning signs of injury

If you notice any of the following, you’re on the injury train, so be prepared to slow down and stop exercising. Heed these warning signs of impending injury…

  • Pain and discomfort at the beginning of your workout that becomes worse as you continue to exercise
  • Pain that forces you to alter (shorten) your stride or limp
  • Pain you feel coming on after a few minutes of exercise and continues at a low nagging level
  • Pain that stops you exercising
  • Pain that persists after you stop exercising
  • Pain that persists during normal daily activities and interferes with them
  • Pain when you walk up stairs or uphill
  • Pain or stiffness, especially in the mornings or after rest
  • Pain that continues for more than a day or two, worsens and does not get better
  • Pain and tenderness in one particular spot on a bone, muscle or joint that you can actually feel with your fingertips. You can check this by feeling the same spot on the other side of the body — if there’s no pain there, you probably have an injury
  • If you need to take anti-inflammatory or painkilling medications such as aspirin, ibuprofen, paracetamol etc.
  • Dull, aching pain, or sharp, severe pain that keeps you awake at night
  • Pain in the joints of ankle, knee or hip


Using this advice will get you well on your way to good aerobic fitness. The benefits will become noticeable immediately, as you feel better, have more energy and experience the dozens of health benefits that endurance exercise has to offer.

How do you estimate your maximal heart rate?

Subtract your age from 220 and multiply this figure by .65 and .80 to get a training heart rate range.

Here’s an example. If you are 30 years old, your estimated maximal heart rate is 190 (220-30 = 190). Then multiply this by .65 and .80 to get your range. Ie, 190 × .65 = 124, 190 × .80 = 152, so the range for your heart rate is 124–152. If you’re above this, slow down, and if you’re below this when doing your cardio workout, speed up.



Roy Stevenson has a Masters degree in exercise physiology from Ohio University. He has taught exercise science and nutrition at Seattle University, University of Puget Sound, Highline Community College and Lake Washington Technical College. W:

Roy Stevenson

Roy Stevenson

Roy Stevenson has a Masters degree in exercise physiology from Ohio University. He has taught exercise science, health and nutrition at community college and university levels. As a freelance writer, Roy has more than 300 articles on health, fitness and sports conditioning published in over 60 regional, national and international magazines.

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