Optimising Cardio During Contest Prep
By Thomas Rowland

Itís competition season and time to strip away the body fat to be as peeled on stage as possible. As every bodybuilder knows, in order to lose weight, one must be in a negative energy balance.

Energy balance = energy intake Ė energy expenditure

If energy balance is positive, you will gain weight, if energy balance is negative, you will lose weight. This equation tells us that to drop weight we can decrease energy intake and/or increase energy expenditure. Obviously, contest prep involves both these factors, as calories are lowered and, unfortunately, the dreaded cardio is performed. While bodybuilding is an extremely demanding and difficult sport, its goals are very simple. Lose as much fat as possible and retain as much muscle as possible.

For contest condition, bodybuilders want to reduce subcutaneous (beneath the skin) fat from adipose tissue, as it is this fat that contributes to body composition. The process by which this occurs is the breakdown of stored fat (through lipolysis), into free fatty acids (FFAs). These FFAs can then be transported via the circulation to other tissues such as muscle, where they are oxidised or Ďburntí, to provide energy.

In general, endurance type exercise can aid contest prep fat loss by increasing energy expenditure (or burning calories) thereby lowering energy balance as well as by triggering metabolic adaptations that increase ones capacity to oxidise fat. The primary adaptation to endurance training is an increased oxidative phenotype, or in other words, a greater reliance on fat as a fuel source. Down at the molecular level, this is likely explained in part by increased mitochondrial biogenesis (more mitochondria) and an up-regulation of enzymes involved in fatty acid metabolism. The mitochondria are the organelles, or Ďpartsí, of the cell that can use fat to produce energy. The more mitochondria there are, the greater the capacity to use more fat for energy.

So now thatís out the way, letís get down to some practical advice. When strength training is performed alongside endurance training, it is known as concurrent training. It has been well documented that concurrent training impairs (not completely blunts) the adaptation to strength training, preventing optimal increases in muscle mass, strength and power (1). That being said, cardio is still necessary for the large majority of bodybuilders to get into the best shape possible. This leaves the question then of how can we minimise the interference effects of concurrent training to ensure we retain as much muscle as possible but still lose fat? Recently, a comprehensive meta-analysis (a study of studies) was published that looked at how different variables influence the concurrent training effect (2).

The authors demonstrated that running endurance exercise significantly impaired lower body hypertrophy developments to strength training compared to strength training alone, but that cycling endurance exercise did not. A similar result was obtained for strength and power as well. It was speculated that this could be because cycling more closely mimics strength exercises, and that continuous running causes much greater muscle damage than cycling (2). Therefore, performing cardio that more closely mimics resistance type exercises such as squatting and deadlifting will be more beneficial for a bodybuilder. With these results in mind, it is also likely the modality of the cardio you perform will influence your ability to retain muscle during energy restricted contest prep. So clearly the modality of the cardio you perform has a big effect. Interestingly though, the mode of cardio did not influence hypertrophy gains of the upper body, so the interference effect of concurrent training is also body part specific (2). The authors also demonstrated that the more days per week cardio was performed, and the longer the cardio session was, the greater the impairment on hypertrophy, strength and power development.

With regards to body fat loss, the same study found a positive relationship between the percent of maximal heart rate (HRmax) cardio was performed at and the extent of body fat loss (2). So the lower the percent HRmax cardio was performed at, the less body fat was lost, and the higher the percent HRmax, the greatest amount of body fat lost. This suggests that high intensity interval training (HIIT), which is performed at about 90-100% of HRmax, would be better cardio for body fat loss during contest prep. Now, that being said, this was just an association, and while not many large, randomised controlled trials have been conducted directly comparing different types of cardio and their effect on energy restricted fat loss, there are trials in the literature that suggest HIIT does promote greater fat loss (3,4).

Youíll see the following example on numerous articles about HIIT, but itís worth repeating here. Visually, just compare pictures of an endurance runner and a sprinter, I think I know whoís training Iíd prefer to follow for bodybuilding!

So now we know HIIT, and cardio that closely resembles weight training is preferable, when is it most effective to perform? Fed or fasted is a common debate all bodybuilders are familiar with. The rational behind why cardio should be performed fasted, is because with fasting, rates of lipolysis are greater and a shift towards fat oxidation occurs. Thus performing cardio when lipolysis is high, there are ample FFAs available to use for fuel and this should result in the greatest amount of fat burning. Sounds reasonable, but what does experimentation say? Brad Schoenfeld published a review article a few years back debunking this myth (5). Essentially, experimental studies show that:

  • Fat oxidation is not impaired with pre-exercise carbohydrate consumption regardless of exercise intensity, because plasma FFAs are not rate limiting for fat oxidation (5).

  • Eating before exercise actually functions to increase the thermic effect of exercise, meaning you burn more calories post-exercise when exercise is performed in the fed state (5).

  • Fasted cardio increases rates of muscle protein breakdown compared to fed state cardio (certainly not what a competing bodybuilder wants) (5).

  • Finally, doing cardio in the fasted state means it is physically harder to train intensely, resulting in less calories being burnt both during and post exercise (5). Hopefully thatís put that argument to rest. Donít do fasted cardio!

    Next up is whether to perform cardio before or after your resistance training session. This is an active area of research and as of now there are not any firm conclusions. At the molecular level, the cellular pathways triggered by endurance exercise that lead to adaptation are believed to inhibit the pathways that resistance exercise activates that lead to muscle hypertrophy. Studies that have looked at the effect of exercise order on these pathways have noted that exercise order appears to alter the molecular responses compared to each exercise alone (6,7). One recent animal study suggested performing cardio after weights will blunt the anabolic response to weight training (7). However, while interesting, studying animals and just looking at a few molecules after exercise does not help us offer any meaningful practical advice to well trained bodybuilders.

    A recent study that looked at a physiological response (muscle protein synthesis), showed that protein ingestion post-exercise where continuous endurance cycling was performed after resistance exercise, resulted in increased rates of myofibrillar protein synthesis, promotion of oxidative responses and attenuation of markers of muscle protein breakdown compared to no protein ingestion (8). Therefore, doing your cardio after weight training will not nullify the anabolic effect of the weight-training bout as long as you ingest some protein after exercise. However, this study didnít have a group that performed the exercise bouts in the reverse order so a direct comparison of what exercise ordering is optimal cannot be made.

    Interestingly, a recent 8-week training study in untrained females demonstrated that exercise order did not influence gains in lean body mass, strength, VO2max or influence body fat levels in response to a 4 days per week concurrent training programme (9). It is also worth noting that in the meta-analysis discussed earlier on in this article it was found that performing cardio and resistance exercise on the same day possibly impaired hypertrophy compared to if they were performed on separate days, although this difference wasnít statistically significant (2).

    Before any firm conclusions are made, I would like to see further studies examine exercise order in well-trained athletes, whether the type of endurance exercise (HIIT or continuous) has an effect and whether nutritional interventions can overcome any interference. Nonetheless, bearing all the above in mind I would recommend performing weights and cardio in the order that you prefer. Personally, I would prefer to weight train then do cardio, as I think cardio before hand would effect my intensity with the weights. Perhaps ideally however, perform cardio on a Ďrestí day to prevent any possible interference that might occur. Of course, this becomes impractical when cardio frequency has to be increased. If cardio is performed after resistance exercise then do cardio on an upper body day to prevent body part specific interference in the lower body muscles.

    You may also be wondering how many times a week you should be doing cardio. Well, remember earlier on in the article it was mentioned that the more cardio performed per week the greater the impairment on hypertrophy, strength and power (2). So as a general rule of thumb, do as little cardio as possible while still making progress. This will of course be very individual, but itís a good idea to maybe start out with two HIIT sessions a week and monitor your progress from there. When necessary, if progress stalls, you can increase this to three and then maybe four times a week etc. A basic example contest prep training programme might look something like the one below. For ease of reading I have written it as a 6-week block, but of course a proper contest prep will last much longer than this. Please note this is not a programme I am advising everyone follows, it is merely a quick, non-specific example to demonstrate how you can fit in cardio around a periodised weight training protocol:

    1PowerModerate UpperHIITModerate LowerHIITHeavy UpperRest
    2Heavy LowerModerate UpperHIITModerate LowerHIITPowerRest
    3Heavy UpperModerate LowerHIITModerate UpperHIITHeavy LowerHIIT
    4PowerModerate LowerHIITModerate UpperHIITHeavy UpperHIIT
    5Heavy LowerModerate Upper + HIITHIITModerate LowerHIITPowerHIIIT
    6Heavy LowerModerate Upper + HIITHIITModerate LowerHIITHeavy UpperHIIT

    In this scheme, 12 moderate or hypertrophy sessions are performed, 8 heavy sessions and 4 power. Cardio begins at a twice-weekly frequency on non-weight training days. After two weeks, cardio frequency is increased to 3d/w for two weeks, and is still performed on non-weight training days. Then in weeks 5 and 6, cardio frequency is increased even further to 4d/w, in which cardio is performed on non-weight training days with one HIIT session being performed after a hypertrophy/moderate upper body session.

    In conclusion, to optimise fat loss while simultaneously maintaining muscle mass, the practical advice regarding cardio that we can deliver based on the discussion above is as follows:

  • HIIT is the preferable type of cardio to perform.

  • The mode of HIIT should more closely mimic weight training. For example, cycling, sprinting (sprinting is biomechanically different to continuous running), rowing, pushing a car round a car park etc.

  • Cardio should be performed in the fed state.

  • Cardio should be performed preferably on a rest day but if this isnít possible, perform in the order you prefer but ideally after an upper body session.

  • Start with as little cardio as possible to minimise any interference effect and gradually increase frequency and/or intensity as your prep progresses or fat loss stalls.

    Now for those who swear by continuous or low intensity steady state cardio, the argument here is not that it doesnít work to some degree, but that itís not likely to be optimal for fat loss or muscle retention. Consideration should also be paid however to the cardio that you enjoy or prefer doing, because, surprise, surprise, you are more likely to stick to what you enjoy than what you donít. I would recommend ditching the hoodie and treadmill, and basing your cardio around HIIT, but if for example, you love going for a run around the woods or forest, then perhaps include that from time to time as well.


    (1) Fyfe JJ, Bishop, DJ, and Stepto NK. Interference between Concurrent Resistance and Endurance Exercise: Molecular Bases and the Role of Individual Training Variables. Sports Medicine (44), 743:762, 2014

    (2) Wilson JM, Marin PJ, Rhea MR, Wilson SMC, Loenneke JP and Anderson JC. Concurrent Training: A Meta-Analysis Examining Interference of Aerobic And Resistance Exercises. Journal of Strength and Conditioning Research 26 (8): 2293-2307, 2013.

    (3) Tremblay A, Simoneau JA and Bouchard C. Impact of Exercise Intensity on Body Fatness and Skeletal Muscle Metabolism. Metabolism. 43 (7), 1994.

    (4) Trapp EG, Chisholm DJ, Freund J and Boutcher SH. The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women. International Journal of Obesity. 32: 684-691, 2008.

    (5) Schoenfeld B. Does Cardio After an Overnight Fast Maximize Fat Loss? Journal of Strength and Conditioning Research. 33(1), 2011.

    (6) Coffey VG, Pilegaard H, Garnham AP, OíBrien BJ and Hawley JA. Consecutive bouts of diverse contractile activity alter acute responses in human skeletal muscle. Journal of Applied Physiology. 106:1187-1197, 2009.

    (7) Ogasawara R, Sato K, Matsutani K, Nakazato K and Fujita S. The order of concurrent endurance and resistance exercise modifies mTOR signalling and protein synthesis in rat skeletal muscle. American Journal of Physiology: Endocrinology and Metabolism. 306:1155-1162, 2014.

    (8) Camera DM, West DWD, Philips SM, Rerecich T, Stellingwerff T, Hawley JA and Coffey VG. Protein Ingestion Increases Myofibrillar Protein Synthesis after Concurrent Exercise. Medicine and Science in Sports and Exercise. E-pub ahead of print. 2014

    (9) Davitt PM, Pellegrino JK, Schanzer JR, Tjionas IH and Arent SM. The Effects of a Combined Resistance Training and Endurance Exercise Program in Inactive College Females: Does Order Matter? Journal of Strength and Conditioning Research. 28(7): 1936-45, 2014.