Cardio: Will You Burn Fat or Lose Muscle?
Cardio: Will You Burn Fat or Lose Muscle?
By Daniel Gwartney, MD
The end goal for most people in the gym is to translate the effort of lifting literally tons of iron into a healthy, leaner and more muscular physique. However, many men are dissatisfied with the results of their struggles, even though an impressive amount of muscle may have developed.
Muscularity, in the eyes of a bodybuilder, is meaningless if it is hidden beneath a blanket of fat, blurring the definition between muscle groups and often giving the appearance of nothing more than generalized obesity. It is the hardened, if not chiseled, look of a mythical hero that is typically sought, but rarely obtained.
Bodybuilders often turn to cardio training in their attempts to shed the unwanted adipose. Unfortunately, they often choose an inappropriate cardio routine that cannibalizes their hard-earned muscle and may even cause overtraining or injury.1 Cardio can be used successfully to reduce body fat, without sacrificing strength or muscularity. To do so, however, requires looking objectively at the underlying problem and then determining the proper solution.
Cross-Training Conundrum
It would be a meaningless gesture to begin a fat-loss program unless attention was focused upon the diet first.2 Without dwelling on this point, other than to raise it to the level of awareness, no cardio program for fat loss should be attempted without first addressing calorie control.
Bodybuilders need to approach cardio as bodybuilders. Despite being athletic individuals, they are not athletes in the sense that their sport is dependent upon complex, explosive movements or everlasting endurance. Many athletes attempt to be bodybuilders without giving up on being athletes, buying into the idea of cross-training. Cross-training is an excellent way to develop overall fitness and athletic skills, but it does not allow one to truly excel in any single specific sport. Instead, cross-training is popular because it aims to provide balance and variety to the general public, which is more interested in recreational fitness and the social interaction of sports.
A bodybuilder needs to approach cardio as a tool, increasing low-intensity activity to maintain the metabolic rate, burning more calories within a given period of time, without sacrificing muscle or energy, or causing injury.
There are few studies looking at the impact of cardio training on muscle gains. The definitive study on the compatibility of strength training and endurance training was reported by Kraemer et al.3 Healthy, adult men were divided into groups that included those who performed only endurance training, those who performed only strength training and those who combined strength and endurance training. This study found that though the combined group (strength and endurance trained) made progress in both endurance and strength measurements, their progress was not as great as in those who focused solely upon either strength or endurance training. In other words, men who only strength trained were stronger and made better progress in the gym than those who combined strength and endurance training, and those who only endurance trained were better runners than those who combined strength and endurance training.
Applying these results to the goals of a bodybuilder would suggest that combined endurance and strength training would at least slow any gains to be made in the gym. However, for those who are only lifting to maintain muscle mass and/or for general health and well-being, this and other studies have shown combined training can provide moderate benefits in both cardio conditioning and strength.3,4
Designing a Cardio Program
There are further issues that a bodybuilder must consider when designing a cardio program. Briefly, these include time, equipment, injury and specificity. Time is an obvious barrier. It can be difficult to schedule workouts, let alone adding 20-60 minutes for cardio. Generalized recommendations for cardiovascular health suggest three 20- to 40-minute sessions of light-to-moderate activity per week; for bodybuilders who want to drop body fat, more cardio may be required depending on current body fat levels and the recommendation of their contest-prep coach.
Most gyms have a variety of equipment to choose from for cardiovascular fitness or fat loss. A standard treadmill is as effective as any of the more complex cardio equipment. There are some that are more challenging, such as the revolving staircase if your gym has one of those. If weather permits, brisk outdoor walking or running is even more effective (and can be less monotonous) than using a treadmill. Selecting a route with hills and inclines can provide a serious cardio workout. For the competitive bodybuilder, group sports and exercise classes should be avoided.
In part, the recommendation against group exercise classes involves the high risk of injury,5 as more injuries occur in these classes than anywhere else in the gym. Most classes are designed for cardiovascular conditioning or weight loss (including muscle loss) and involve quick movements that require practice and agility. Movements like knee-ups, grapevines and weighted good mornings at a pace of 60 per minute may not be overly risky to the 140-pound mother of two, but to a 210-pound bodybuilder, they can cause serious joint or connective tissue injury.
Many of the machines can also cause joint stress, such as the elliptical trainers or rowing machines. These machines have fixed pedals or handles and if one is not properly aligned, inflammation or injury can occur. Many bodybuilders cannot use the fixed pedals properly, due to the muscle mass in their thighs, causing stress at the hips, knees and ankles. Even the use of some bikes may be harmful. Cycling has been associated with inflammation of the soles of the feet, carpal tunnel syndrome and even nerve damage in the groin.6,7
Most people choose activities that rely exclusively on leg movements for cardio training, such as brisk walking, jogging or biking. These choices make the impact of the cardio specific to one muscle group, which can be quite disadvantageous. Placing constant demands upon the legs (quads, hams and glutes) can slow, or even stop, any gains that might be made in these muscle groups as they will not have sufficient rest to recover from weight training or any opportunity to achieve a period of hypertrophy.8,9 Using this example, cardio should not be performed on leg day, as it would deplete glycogen stores and increase inflammation prior to the workout.10,11
Recovery is a major point against strenuous or prolonged cardio workouts. Endurance athletes are under high levels of oxidative stress12, they deplete the glycogen stores of the exercised muscles13, and may also suffer from dehydration and overheating.8,14,15 These are all extremely negative factors, which bodybuilders should avoid.
A Bodybuilder’s Lifestyle
An ideal cardio program for a bodybuilder should first take into consideration his or her usual lifestyle. If one’s occupation involves a great deal of activity, such as manual labor, then there is little need for more activity and greater benefit would be gained by enforcing a stricter diet. If one’s occupation is fairly sedentary, such as having a desk job or driving, then using the cardio program to increase the amount of activity is a sensible approach. Regardless of the case, for the purposes of bodybuilding, cardio should be used only to increase the amount of low- to moderate-intensity activity for the purpose of increasing the number of calories burned.
The best choice for any one person is the choice that he or she will follow consistently. The simplest approach is to choose an outdoor route that has hills and flat stretches, alternately walking or jogging as the terrain and conditioning allows. Many people speak of a target heart rate, but since not everyone actually measures their heart rate while exercising, others recommend maintaining a pace that’s low enough to allow you to talk in short sentences, but not so leisurely as to allow a long dissertation on the hidden meanings of “The Canterbury Tales.”
To maximize fat loss, cardio should be done first thing in the morning, after fasting (thus, before breakfast). Plenty of water should be consumed before and during cardio.13,16 Caffeine, taken 30-60 minutes prior to the exercise, will improve fat burning,17 but that would require getting up an hour earlier, taking a caffeine tablet or brewing coffee, and then exercising. Many people also have difficulty tolerating caffeine on an empty stomach, so the use of caffeine may or may not be of some benefit.
Again, these guidelines do not specifically apply to recreational or novice lifters, as they may see great gains due to neuromuscular adaptation (basically improved coordination). Bodybuilders on steroids will be able tolerate a much higher level of cardio training, as most anabolics provide protection from muscle loss either by decreasing muscle breakdown, increasing protein uptake into the muscle, or both.17 Due to their greater mass and strength, steroid-using bodybuilders may be at higher risk for injury during cardio. Low doses of certain anabolics, including the popular pre-contest drug Winstrol, are rumored to be used by professional track athletes and cyclists to avoid overtraining and prevent muscle loss.
Losing Hard-Earned Muscle?
Many bodybuilders include cardio in their training to aid in fat loss, but many also sacrifice their hard-earned muscle and prevent future gains due to the nature and amount of cardio chosen. Recommendations for a cardio program are specific to the individual, taking into consideration his or her current body fat levels and goal. Bodybuilders should only use cardio to support the fat-loss efforts of a strict diet.
Attention needs to be paid to the style of training used for cardio, as many of the machines, classes and activities may cause injury or impair later strength training. Cardio will provide best fat-loss results if performed upon rising, before eating, while in the fasted state. Drink at least one liter of water during cardio; some people may choose to use 100-200 milligrams of caffeine to increase fat burning. Sports beverages should not be used in place of water, as many of them contain an excessive amount of carbohydrates. It’s best to include variety in your cardio training, altering the course, speed and inclines of the routes or activities. While some experts recommend high-intensity interval training (HITT) and others a more constant low- to moderate-intensity style, consistency is the key factor that will determine success.
References:
1. Fry AC, Kraemer WJ. Resistance exercise overtraining and overreaching: Neuroendocrine responses. Sports Med 1997 Feb;23(2):106-29.
2. Kraemer WJ, Volek JS, et al. Influence of exercise training on physiological and performance changes with weight loss in men. Med Sci Sports Exerc 1999 Sep;31(9):1320-9.
3. Kraemer WJ, Patton JF, et al. Compatibility of high-intensity strength and endurance training on hormonal and skeletal muscle adaptations. J Appl Physiol 1995 Mar;78(3):976-89.
4. Charlton GA, Crawford MH. Physiologic consequences of training. Cardiol Clin 1997 Aug;15(3):345-54.
5. Unverdorben M, Neuner P, et al. Traumatology - the Achilles’ heel in the rehabilitation of cardiovascular outpatients? Int J Sports Med 1997 Jan;18(1):62-5.
6. Cherington M. Hazards of bicycling: from handlebars to lightning. Semin Neurol 2000;20(2):247-53.
7. Mellion MB. Common cycling injuries. Management and prevention. Sports Med 1991 Jan;11(1):52-70.
8. Gonzalez-Alonso J, Calbet JA, et al. Muscle blood flow is reduced with dehydration during prolonged exercise in humans. J Physiol 1998 Dec 15;513(Pt 3):895-905.
9. Qayyum MS, Freemantle CA, et al. Potassium loss from skeletal muscle during exercise in man: a radioisotope study. Exp Physiol 1993 Sep;78(5):639-48.
10. Camus G, Deby-Dupont G, et al. Are inflammatory factors involved in strenuous exercise and sepsis? Intensive Care Med 1994 Nov;20(8):602-10.
11. Miles MP, Clarkson PM. Exercise-induced muscle pain, soreness, and cramps. J Sports Med Phys Fitness 1994 Sep;34(3):203-16.
12. McBride JM, Kraemer WJ, et al. Effect of resistance exercise on free radical production. Med Sci Sports Exerc 1998 Jan;30(1):67-72.
13. Murray R. Rehydration strategies - balancing substrate, fluid, and electrolyte provision. Int J Sports Med 1998 Jun;19 Suppl 2:S133-5.
14. Febbraio MA. Does muscle function and metabolism affect exercise performance in the heat? Exerc Sports Sci Rev 2000 Oct;28(4):171-6.
15. Gonzalez-Alonso J, Calbet JA, et al. Metabolic and thermodynamic responses to dehydration-induced reductions in muscle blood flow in exercising humans. J Physiol 1999 Oct 15;520(Pt 2):577-89.
16. Hargreaves M, Dillo P, et al. Effect of fluid ingestion on muscle metabolism during prolonged exercise. J Appl Physiol 1996 Jan;80(1):363-6.
17. McCarty MF. Optimizing exercise for fat loss. Med Hypotheses 1995 May;44(5):325-30.
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