Fitness enthusiasts and athletes can be a little tribal — that is, they like what they do and tend to dismiss or deride other codes, sports or training approaches. Nowhere is this more obvious than in the arguments and discussions about weight training versus cardio (aerobic training). Should you do cardio, how much, how long? Some people in the weight training and bodybuilding communities believe that you don’t need aerobic exercise for peak fitness.
In a way, this is not a sensible proposition because aerobic fitness -- as measured by various cardiovascular parameters such as oxygen consumption (VO2 max), heart rate reserve (difference between resting and maximum heart rate), and heart rate recovery (reduction in beats per minute after exertion) -- has been linked to protection from cardiovascular disease or heart attack. Studies of various groups of exercisers confirms this. A high level of aerobic fitness is generally not achievable unless some form of pure aerobic training is part of a fitness program.
Doing weight or strength training alone does increase fitness and cardiovascular efficiency, especially if circuit training is used, but this is unlikely to match the aerobic fitness that can be acquired by including a strong dynamic program of movement with aerobic activities like running or cycling. And in any case, there is no reason not to do both.
If the critics of aerobic training are referring to competitive endurance training, then that’s another discussion because marathon or triathlon training, for example, is training for a particular competitive activity and goes well beyond what is required for general fitness or wellness.
Exercise Type and Wellness Outcomes
Consider this study. A team from the Harvard School of Public Health studied 44,452 men enrolled in the Health Professionals’ Follow-up Study at 2-year intervals from 1986 to 1998. Here is what they found in relation to heart attack risk (as defined by a fatal or non-fatal attack) and exercise type and intensity.
- Total physical activity, running, weight training, and rowing were each inversely associated with risk of CHD (coronary heart disease).
- Men who ran for an hour or more per week had a 42% risk reduction.
- Men who trained with weights for 30 minutes or more per week had a 23% risk reduction.
- Rowing for 1 hour or more per week was associated with an 18% risk reduction.
- Average exercise intensity was associated with reduced heart disease risk, independent of the total volume of physical activity.
- A half-hour per day or more of brisk walking was associated with an 18% risk reduction.
- Walking pace was associated with reduced heart disease risk, independent of the number of walking hours.
- Total physical activity, running, weight training, and walking were each associated with reduced heart disease risk. Average exercise intensity was associated with reduced risk independent of the number of MET-hours spent in physical activity.
Note the role for exercise intensity in improving heart disease risk outcomes. This does not imply that you have to do everything at 90% of your maximum heart rate; it means that you will benefit most from exercise at moderate to high intensity — in the range of 70 to 90% of your maximum heart rate. A progressive program of training is required to achieve these higher training intensities.
In another study in the journal Atherosclerosis, 35,402 male runners were studied over 7.7 years. For each kilometer they ran per day, their risk declined 5% for fatal and nonfatal coronary heart disease (CHD) and artery bypasses. Their risks for nonfatal heart attacks and angina declined 7% per km. Compared to running less than 3 kilometers per day, running 9km/day reduced risks 65% for angina, 29% for nonfatal CHD and 26% for fatal and nonfatal CHD. The authors concluded that exceeding the guidelines for physical activity levels produces important reductions in heart disease risk.
Arterial Stiffness and Weight Training
Several studies have demonstrated that weight training has a tendency to produce stiffening of the arteries (poor arterial compliance). Arterial stiffness is related to high blood pressure and an increase in heart disease and stroke risk. While this condition needs to be studied more widely in weight trainers to understand and evaluate the nature of the risk, balancing weight training with aerobic exercise, which tends to reduce arterial stiffening, seems like a good safeguard.
Should I Do Weights or Cardio?
The bottom line here is that any exercise is better than none, and the total volume and intensity of exercise counts toward the ultimate training and wellness effect. Moderate- to high-intensity and volume aerobic exercise has clear benefits for heart and lung conditioning that are more or less unique to aerobic exercise.
Weight training has its own benefits in strength and muscle enhancement or maintenance, flexibility, plus some cardiovascular benefit. Interval training at high intensity complements the other two. Why omit one? Why not do all three types of exercise if you are able? That’s certainly what the latest physical activity guidelines are hinting at.
You can't get optimum fitness from one type of physical activity training. Different systems in your body are targeted when you specialize in one type of exercise. If you need optimum performance for sports competition, then you do need to specialize. But if you're training for wellness and a high level of all-around fitness, you need to do at least some pure aerobic training as well as weight training two to three times a week.
The "weights or cardio" argument is dead. Long live all-around fitness.
Tanasescu M, Leitzmann MF, Rimm EB, Willett WC, Stampfer MJ, Hu FB. Exercise type and intensity in relation to coronary heart disease in men. JAMA. 2002 Oct 23-30;288(16):1994-2000.
Williams PT. Reductions in incident coronary heart disease risk above guideline physical activity levels in men. Atherosclerosis. 2010 Apr;209(2):524-7.
Miyachi M, Kawano H, Sugawara J, Takahashi K, Hayashi K, Yamazaki K, Tabata I, Tanaka H. Unfavorable effects of resistance training on central arterial compliance: a randomized intervention study. Circulation. 2004 Nov 2;110(18):2858-63.