We were recently discussing on our forum about how much exercise is needed to produce results. We had also previously discussed training volume versus intensity with such notable interviewees as Layne Norton and Borge Fagerli and it's fair to say that the topic is one which is likely to be debated for as long as people go to the gym and lift hunks of iron. With this in mind let's look at a new research study just published comparing moderate versus high volume exercise routines and the effect on weight loss (1).
Weight loss programmes often disappoint with diets leading to compensatory mechanisms designed to defeat weight loss (lower metabolic rate and increased hunger). Can these mechanisms be triggered by increased aerobic exercise?
A trial was set up using healthy, overweight young men from Denmark. Subjects were split into three groups, a sedentary control group, a group who performed 30 minutes of exercise daily for 13 weeks, and a group performing 60 minutes of exercise daily for 13 weeks. The moderate volume group aimed to burn 300 calories per workout while the high volume group had a target of 600 calories a day to burn off.
The moderate volume group achieved a greater average weight loss (3.6kg versus 2.7kg) as well as greater body fat loss (4kg versus 3.8kg). Although the high volume subjects burned off twice as many calories while training, they offset this greater calorie burn. In fact, energy balance was 83% more negative than expected in the moderate volume subjects, but 20% less than expected in the high volume group. No changes were found in energy intake or non-exercise physical activity that could explain the compensatory mechanisms associated with 30 vs 60 min of daily exercise.
A moderate volume exercise routine caused better than expected results while a high volume routine caused a degree of compensation which offset the benefits of greater exercise.
What does this all mean?
On the face of it, this study suggests that by keeping our overall exercise volume down, it can lead to better results, at least when it comes to weight loss in moderately overweight individuals. Research and real world experience both support the fact that as training sessions last longer the performance of participants declines as energy subsides and fatigue sets in. In fact, the researchers remarked that the moderate training volume group outperformed their predictions, postulating this could be due to the fact that a brief training session, where motivation remains high, could lead to greater activity post workout. By contrast, those performing a daily hour long workout were deemed more likely to coast their sessions or spend the rest of the day in a comparative stupor on the couch. Before we accept uncritically the results of this research we must consider some important caveats.
Cardio versus weight training
While the researchers deemed that a daily aerobic session consisting of 30 minutes activity is moderate, it is hard for those who train 3-4 times a week to see it that way. For weight training individuals in particular, trying to train for 30 minutes daily would be a considerable challenge for most. For the average gym goer to train one hour daily would require a long time to adapt to the workload. It is therefore not difficult to believe that training cardio daily, especially for an untrained, overweight individual, is not going to correlate necessarily to someone who only lifts weights. We need to remember that while endurance training can lend itself to daily activity it is much more difficult to perform high intensity activity daily. This alone, makes this study not transferable to populations engaged in regular high intensity activities such as weight training, sprinting or team sports.
Untrained versus trained subjects
The use of untrained subjects is something that again will throw off results. If we were to extend the notion of 30 minutes of cardio being better than 60 minutes for weight loss then we would expect that among experienced endurance runners, short sessions were more popular. By contrast, empirical evidence shows that the more trained an endurance athlete becomes the greater their volume of work which is epitomised by the Kenyan school of running where several hours a day of training is performed. These elite athletes don't become worse (or fatter) as they perform more activity. Rather, being used to dietary control their greater training volume results in better results as they are able to avoid excess over eating to compensate for increased training volume.
While it is tempting to look at studies such as this one and take their results at face value, we have to consider the degree of relevance to ourselves. All that can be said for this study is that for untrained, overweight people, better results seem to occur by keeping workout sessions short. For those who are able to sustain a higher degree of performance this does not hold true though.
1. Rosenkilde M, et.al (2012): Body fat loss and compensatory mechanisms in response to different doses of aerobic exercise - a randomized controlled trial in overweight sedentary males
Author: Reggie Johal
Reggie Johal is a former Great Britain American Football player with a background in strength and fitness coaching with articles published in many leading online and print magazines including Muscle and Fitness. Reggie is the founder of Predator Nutrition.