Finding the Right Blend of Cardio and Weight Lifting for Muscle Growth

I was recently asked “will an intense cardiovascular workout after lifting heavy weights build my muscles bigger and faster?” The question and answer is complicated. The question itself needs quite a bit of clarification. The answer is a factor of diet, body type, training objectives, and more. 

First off, intensity must be defined. It is something emotional as well as physical and it can be measured in absolute terms as well as relative.

Mental Intensity

Mental intensity is, essentially, getting “psyched” to do something. These feelings stem from the fight-or-flight response. When we sustain a potentially debilitating and shock-inducing injury or we’re gripped with fear or bursting with aggression, activity of the adrenal gland releases adrenaline into the bloodstream to keep the mind and body functioning. 

This results in our highest intensity and keenest mental focus for split-second decision making. Oxygenated blood flow to the brain and muscles rises dramatically as part of an increase in heart rate, blood pressure, respiratory rate, metabolic rate, and blood glucose concentration. However, emotional intensity cannot be maintained at high levels indefinitely because we “burn out;” adrenal fatigue results from persistent stress.

Physical Intensity 

Physical intensity in exercise refers to the degree to which a muscle is fatigued within a particular unit of time. Absolute exercise intensity determines the total quantity of fuel (i.e., calories) required. We only have so many useful calories available in our bodies to do work in a given period of time. In addition, lactic acid and other metabolic wastes cannot be purged without rest and recovery.

The Meaning of Heavy Weight Lifting

“Heavy” weight likewise has a proper meaning with respect to resistance or weight employed. Resistance is correctly defined as heavy when an individual cannot complete, successfully and individually, more than six repetitions of the given movement. This repetition limit usually corresponds to a weight that is at least 85 % of that individual’s one-repetition maximum. For example, a weight is heavy if you can perform at least 1 rep but not more than 6; you fail on the seventh attempt. 

Lifting heavy isn’t for everyone, though. Heavy weight is best when the primary objective is an increase in absolute strength and the secondary objective is an increase in size while increases in tone and endurance are minor concerns. Heavy (i.e., maximal) lifting recruits a large number of muscle fiber at once, placing tremendous strain on them and causing them to pack more tightly together, developing what is known as muscular density. 

Weightlifters, powerlifters and strongmen need heavy resistance and heavy resistance demands high intensity. Of course, it is rather difficult to immediately follow one intense workout (grunting under heavy weights) with another (charging like a maniac on the treadmill).

By contrast, bodybuilders, who train with a primary objective of muscular size, typically don’t train heavy. The big muscles of bodybuilders come via moderate resistance, high volume routines. This approach involves more growth via higher fluid volumes inside and between cells, non-contractile proteins that do not directly contribute to force generation, and some connective tissue. 

Heavy lifters are usually the same folks inclined favor principal, compound movements – like squats – that turn out to be more absolutely intense (i.e., burn more calories) rather than relatively intense for specific muscles. This is not to say that others don’t perform squats and the like. The point is: calorie burn is a vitally important factor in muscular growth response. Simply, caloric consumption (i.e., how much you eat) must exceed caloric expenditure (i.e., how much you burn) in order to have growth (either for fat gain or muscle gain).

The Importance of Calorie Intake to Build Muscle

Caloric consumption and expenditure force consideration of body type. People have different structural profiles that reflect height, natural weight, and skeletal proportions: ectomorphy (scrawny), mesomorphy (ideal), and endomorphy (pudgy). Diet and exercise can only control body composition; in other words, body fat and muscle. For some individuals tending towards endomorphy, “intense” cardiovascular activity after a “heavy” weight training session won’t be as detrimental to building muscle as it would to another tending toward ectomorphy. The ectomorph may not be able to eat more than their body is inclined to burn!

Building muscle depends, in no small part, on sound dietary habits. This includes consuming necessary amounts of vital nutrients, eating patterns (frequency and time of day), and overall caloric intake. Good dietary habits complement a good exercise program and vice versa. In addition to muscle stimulus (i.e., appropriate exercise), your body needs excess calories (mostly in the form of the macronutrient protein) for muscle growth.

Cardio and Its Effect on Muscle Growth

Aerobic exercise (continuous, rhythmic movement) is definitely a good way to burn calories while developing the cardiovascular system. However, high intensity cardio workouts – like fast walking, jogging, swimming, or biking – burn a lot of calories! In other words, you burn far too many calories; an intense cardiovascular workout after lifting heavy weights then contributes to the difficulties of so-called hard gainers wishing to build muscle. 

Even for those experiencing less difficulty in bulking up, training too much or too frequently can lead to a state of overtraining which yields a lack of progress. Intense cardiovascular workouts after lifting heavy weights are, for most, going to dramatically deplete muscle glycogen and branched chain amino acids (BCAAs), decrease anabolism, and skew normal hormonal indexes such as testosterone and cortisol.

Stay Focused

While it is important to train hard and with focus, excessive activity or misdirected enthusiasm can prevent packing on muscle. There are many individuals hindering their own progress because they are always training and, therefore, always recovering from their workouts. If you want big muscles, you might just have to be more patient; the cardio may be melting off fat so you can see the muscle but the muscle might not be getting bigger! 

Patience is important. More than a few weight trainers impress themselves easily and might be inclined to brag about gaining 30 to 50 pounds over the course of a few months. However, in most cases, this amount of rapid weight gain is going to include a lot of added fat and retained water. Generally, it is more realistic expect to pack no more than 10 pounds of muscle (lean tissue) per month (absent steroids or other hard-core anabolics). When you’re short on patience, it is crucial to define a goal if you want one thing particularly quickly: Size? Endurance? Fat loss? Strength? You’re not going to get them at the same time in short order.


Let me say that for others, having stated the drawbacks for some people, including aerobics in a conditioning program is great because it elevates endurance and optimizes the vascular system. It helps avoid getting light-headed, dizzy, or experiencing a head rush after several intense sets due to a lack of oxygenated blood flowing through your body.

If you want to build muscle, it may be best to go easier on the cardio workout, at least until you gain experience. Regardless, before starting any vigorous and sustained physical activity, engage in a warm up to raise your respiratory rate and core temperature and increase blood flow, such as:

  • Walking with purpose,
  • Jumping jacks,
  • Jogging in place, or
  • Jumping rope.
This cardio should only take 5 to 15 minutes. Warming up will loosen dormant-muscle, reduce tightness in all soft tissues, and prime motor coordination.

After you’ve defined your goal and you’ve gained a better understanding of your body type, experiment to determine the amount of cardiovascular training that suits you best.

Will an intense cardiovascular workout after lifting heavy weights build muscle bigger and faster? For most people, the short answer is probably not. Getting big muscles in a hurry is best served by moderate-resistance lifting in conjunction with lower intensity cardiovascular activity.

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