TIME 4 FAT LOSS SERIES
This is the Seventh in a series of original articles we will be publishing looking at the science behind fat loss. Join our mailing list to be informed when we have added the latest article.
PART 7 – What is the most effective way of using cardiovascular exercise for fat loss?
The American College of Sports Medicine (1) provides evidence based guidelines which address all of the aspects of the most effective CV fat loss programmes.
How often should we perform CV?
In order to maximise energy expenditure, a frequency of 5 days per week or more is recommended. Research comparing CV programmes consisting of 2,3 or 4 days per week, have shown 2 days a week to be insufficient to produce significant changes in body composition. A 3 or 4 day week programme can produce significant fat loss, with 4 days per week being more effective than 3 (Pollock et al., cited by Heyward and Gibson (2)
How hard should we work?
Initially the intensity should be moderate. This is defined as a level of exertion that noticeably increases heart rate and breathing.
As your fitness improves you should progress to vigorous intensity exercise, which is defined as a level of exertion that substantially increases heart rate and breathing. Progressing to vigorous intensity can provide greater health and fitness benefits and will allow you to expend the required amount of energy in a shorter time (1).
How long should we work for?
30 minutes per day (150 min/week) progressing to 60 minutes or more per day (250-300 min/week). These volumes of exercise do not have to be performed as a continuous effort; you can accumulate them with blocks of intermittent exercise of at least 10 minutes duration (1).
In fact, two sessions of 20-30 minutes throughout the day have been shown to be more effective for fat loss than one session of 40-60 minutes due to the enhanced excess post exercise oxygen consumption (EPOC) (3).
Your body mass will influence how much time you need to exercise for. As lighter people tend to expend less energy per minute than heavier people, they will need to exercise for longer than a heavier person to expend the same amount of energy (4). For example, a person weighing 70kg (154Ib) walking at 4km/hour for 60 minutes will burn approximately 217 kcal while someone weighing 100 kg (220Ib) walking at the same speed for the same duration, will burn approximately 300 kcal.
What type of activities should we do?
Prolonged rhythmical activities using large muscle groups e.g., walking, cycling, rowing, jogging, elliptical trainer, etc
A comparison of different modes of CV exercise showed that they are equally effective in reducing body fat stores (2). However, running tends to be most effective at maximising energy expenditure during continuous exercise (4).
How do we progress a CV programme?
As a guide, increasing duration by 5-10% per week is generally appropriate and well tolerated by most people (5). For example, in week 1 you may perform a total of 20 minutes of moderate intensity exercise per session. This time can then be increased by approximately 2-3 minutes per week until you can perform 60 minutes by weeks 11 or 12. At this point, you reduce the duration to 45 minutes and increase the intensity to vigorous. You can then begin to increase the duration again by 5-10 % per week until you achieve the desired amount of exercise at the higher intensity.
Remember that the longer and harder you work for, the more calories you will expend, but NEVER increase intensity and duration in the same session. You can’t work for longer and harder
How can we maximise energy expenditure?
You may not have the time or the inclination to perform long training sessions, so you need to be able to maximise your energy expenditure in other ways:
Set pace training involves setting the duration of the exercise session, for example 40 minutes, and then setting the intensity as high as possible to ensure that fatigue occurs gradually over the allotted time. As your fitness improves, you will be able to sustain a higher intensity and so expend more energy in the 40 minute period (6), but remember the idea is not to exercise to exhaustion.
Another technique we can use to maximise energy expenditure is interval training. There are many types of interval training, the full discussion of which is beyond the scope of this article, but in short they all consist of a repeated series of high intensity work bouts interspersed with periods of light activity. It is based on the concept that more work can be performed at higher exercise intensities with less fatigue than experienced with continuous exercise (6).
For example, aerobic interval training would involve the participant working at a vigorous intensity, which could be described as “somewhat hard to very hard”, for 2-8 minutes with similar durations of “light” active recovery between work intervals (5). This could involve running for 2 minutes followed by 2 minutes of walking, which would provide an effort to recovery ratio of 1:1. You can begin with intervals as short as two minutes and then increase their duration, so that you are working for longer at the higher intensity. You can also progress to having a recovery period only half the length of the work interval (1:0.5). For example, you may run for 4 minutes and then walk for 2 minutes. Thereby further increasing the time spent exercising at the higher intensity
The number of intervals you perform will depend on your level of fitness and how much time you have. Typically, 5-10 work-recovery intervals would be performed in a session (5).
Remember: You don’t need to run to perform interval training; any form of CV exercise can be used.
How can we make CV exercise sessions more interesting?
You can use a range of different CV training methods in your fat burning programme to help reduce boredom and the risk of over-training and injury. For example, one session may be a long workout of 60-90 minutes at a moderate intensity. On another day, you may perform an aerobic interval session or perhaps a set pace session. As your fitness improves, you might include some high intensity interval training.
While other modes of exercise, such as high intensity interval training (HIIT), can play a valuable role in a fat loss programme, that does not mean that we should abandon more traditional CV exercise per se. It is important to remember that people vary in their abilities and preferences. For some, HIIT may be the most convenient and appropriate form of exercise. For other, perhaps less well conditioned people, moderate intensity, longer duration CV may be more suitable. Remember that a ‘one size fits all approach’ to exercise and fat loss doesn’t work. Ultimately our goal is to create the required energy deficit in a safe, effective, appropriate and enjoyable way. This can take many forms, so ultimately you must decide which is best for you.