Bodybuilder's Cardio Prescription

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Does anyone know when and for how long bodybuilders should undertake gentle long aerobic exercise eg running in order to keep the heart and lungs fit and healthy? A few years ago one used to hear of young body builders dying of heart attacks with the heart all swollen like a geriatric's (admittedly this was prob due to steroid abuse). I'm trying to bulk out with muscle and taking lots of fat-free weight gain; but dont want the heart to be strained. Can u direct me to any journal articles?

Recumbant CycleThickening of left ventricle chamber is actually a normal adaptation for individuals who lift weights, however, it is not indicative of health issues as it is with morbid obesity or congestive heart failure. Interestingly, the heart of aerobically trained athlete adapts by growing larger, thereby, increasing stroke volume. In contrast, the heart of weight trained athlete grows thicker. Basically, when the muscles are under a load during a lift, the heart has to force blood through the vasculature that becomes temporarily occluded from the surrounding contracted muscles This added resistance causes the heart to adapt through hypertrophy, just how other muscles would adapt under load. Also see The Pump.

Let's look at the aerobic prescription guidelines for optimal health, fat loss, and cardiovascular fitness. You can see intensity required for health is not as great as is required for cardiovascular fitness. Also note that aerobic prescription for fat loss is largely dependent upon calories expended when performing traditional cardio programs. Also note that sprint training with long active recovery between bouts can greatly augment fat loss.

Traditional aerobics can tax glycogen stores which are a necessary fuel substrate for intense weight training and other anaerobic activities. However, glycogen stores are typically chronically low anyway during the dieting phase bodybuilders employ months before a competition to reduce body fat. In any event, low glycogen stores can decrease intensity and the time to exhaustion for both weight training and aerobics.

Males who are not accustom to traditional aerobics, can experience depressed testosterone levels at least until their body adapts and their cardiovascular fitness improves. This is because submaximal exercise at lower intensities (i.e. 63% maximum oxygen consumption) stimulates lower cortisol response than higher intensities (i.e. 86% maximum oxygen consumption) (Farrell, 1983; Naveri, 1985). Significant elevations in cortisol seem to reduce endogenous testosterone by acting directly upon the testis to impair the biosynthesis of testosterone (Di Pasquale, 1992, C). This may not be that big of deal for an endurance athlete who can perform a weight training program to retard muscle loss. Bodybuilders on the other hand may have more reason to be concerned, particularly if they are natural bodybuilders and find it difficult to maintain muscle mass when they are dieting down. In contrast, women will not experience depressed testosterone levels during traditional aerobic exercise. In fact, they may see slightly elevated levels since they produce their testosterone in the adrenal cortex in an area adjacent where cortisol also produced in both men and women.

Walking on TreadmillFor these reasons, male bodybuilders may opt for low intensity aerobics training (such as very brisk walking) for long durations (2+ hours) most days of the week (5-6 day/wk) which can be performed instead of traditional aerobics (Jogging for 20-40 minutes, 3-4 days/wk).

Anaerobic exercise such as weight training, sprints, or High Intensity Interval Training (HIIT) can burn nine times fat per calorie expended than can aerobic training alone (Trembblay 1994). Before HIIT is performed, a general conditioning period of several weeks is typically suggested to acclimate the body before higher intensities are introduced. An active recovery of approximately 4 minutes is suggested allowing Creative Phosphate stores to be replenished, so maximal or near maximal intensities can be achieved during each bout.

I do not currently know of any studies comparing the time of day of exercise to actual weight loss or fat loss. Although one study reported the time of exercise does not appear to influence subsequent caloric intake (O'Donoghue 2010). Also, exercising before or after breakfast also does not seem to influence subsequent calorie intake (Maraki 2005, Deighton 2012). However, perceived exertion may be greater for morning exercise as compared to evening exercise (Maraki 2005).

I would suggest the best time of day to perform your cardio exercise will come down to the time you find it most convenient, the time you're more likely to consistently put in the time. With HIIT as with weight training, a time of day you are feeling you're strongest would be ideal.

Keep in mind that fat loss will primarily be achieved through diet with a subtle calorie deficit, just enough to elicit fat loss but not so great to waste muscle and decrease energy required for intense weight training.

To monitor your progress, so appropriate adjustments can be made to both your exercise and dietary regimen, find someone to take periodic skin fold measurements. This can be particularly helpful to make sure you are not consuming too many calories during your bulking up phase, or to ensure you are not over dieting during your cutting phase. Also see Diet Development.

You can search for further studies on PubMed (external link opens in separate browser window) also listed on our Journal Links page (Under Various).

Deighton K, Zahra JC, Stensel DJ (2012). Appetite, energy intake and resting metabolic responses to 60 min treadmill running performed in a fasted versus a postprandial state. Appetite;58(3):946-54

Di Pasquale MG (1992). Maximizing lean body mass without drugs. Drugs in Sports; 1(3):6-12.

Farrell PA, Garthwaite TL, Gustafson AB (1983). Plasma adrenalcorticotropin and cortisol responses to submaximal and exhaustive exercises. J Appl Physiol Respirat Environ. Exercise physiol; 55(5):1441-1444.

Naveri H (1985). Blood hormone and metabolite levels during graded cycle ergometer exercise. Scand J Clin Lad Invest;45:599-603.

Maraki M, Tsofliou F, Pitsiladis YP, Malkova D, Mutrie N, Higgins S (2005). Acute effects of a single exercise class on appetite, energy intake and mood. Is there a time of day effect? Appetite;45(3):272-8.

O'Donoghue K JM, Fournier PA, Guelfi KJ (2010). Lack of effect of exercise time of day on acute energy intake in healthy men. Int J Sport Nutr Exerc Metab; 20(4):350-6.

Trembblay A, Simoneau JA, Bouchard C. (1994). Impact of Exercise Intensity on Body Fatness and Skeletal Muscle Metabolism, Metabolism; 43(7): 814-818.


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