Cardiovascular exercise improves endurance and enhances heart health. It also burns fat. Cardio in some form should be a regular part of your fitness program, especially if you have a significant amount of fat to lose – but, as always, your workouts should be tailored toward your goals. If you’re close to your ideal body weight and only primarily want to build strength and lean body mass, you’ll reap greater rewards if you devote a greater portion of your workout time to resistance training. In fact, too much cardio can actually work against you if muscle hypertrophy is your only goal.
There are a number of reasons why you shouldn’t “overdo” the cardio if your primary goal is to only build lean body mass. Hours of cardio can have a catabolic effect on muscle tissue, making it more difficult to develop the muscle strength and definition you’re looking for. Cardiovascular and resistance training adaptations to exercise are different and when you overdo the cardio, you’re sending your body “mixed messages – one catabolic and one anabolic.
This doesn’t mean you shouldn’t do cardio. Even if your main goal is to build strength or lean body mass, cardio should be a part of your fitness program. After all, what’s more important than a healthy heart? Fortunately, there are some things you can do to reduce the catabolic effects of cardio when your goal is to build strength and lean body mass.
Reduce Catabolic Effects: Limit the Duration of Your Cardio Sessions
If you don’t want to tip the scales towards catabolism, reduce the duration of your cardio sessions. Cortisol levels rise significantly after an hour or more of endurance exercise. This can lead to muscle breakdown, especially if your glycogen stores are low. You don’t need an hour or more of steady-state exercise to improve aerobic endurance and condition your heart.
You can get an effective cardiovascular workout in as little as 10 minutes but 20 to 30 minutes is better. The key is to increase intensity. High-intensity interval training or Tabata intervals for 20 minutes will ultimately burn more fat than an hour of moderate-intensity cardio anyway due to the greater metabolic effect and EPOC, excess energy burned after a high-intensity workout is over. Think higher intensity, shorter duration.
Reduce Catabolic Effects: Strength Train before Cardio
If you do cardio and strength training on the same day, do strength-training before your cardiovascular workout if your primary goal is to build lean muscle mass. When your goal is to build strength and lean body mass, you need to maximize the effort you put into lifting. If you’re doing cardio first, fatigue may limit the amount you’re able to lift, especially when you’re working lower body muscles. Begin with strength training and give it your full effort before focusing on cardio.
What about circuit training? Circuit training will boost your heart rate like cardio, but to get the cardiovascular benefits of circuit training you need to have minimal rest time between sets. Not resting between sets will reduce the amount you’re able to lift during the circuits and limit strength gains. Circuit training is a good overall workout, especially if you’re pressed for time, but it’s not ideal for building muscle strength since you need to lift as heavy as possible.
Reduce Catabolic Effects: Optimize Nutrition
Nutrition counts too. Make sure your diet is composed of 20% to 25% protein. Have protein at each meal and with each snack to make sure your muscles have a continual supply of amino acids. Don’t be afraid of carbs. You need carbs to maintain adequate liver and glycogen levels for your workouts. When you exercise in a low-glycogen state, it increases cortisol, which boosts muscle breakdown.
Choose fiber-rich carbs at most meals and simple carbs immediately after a workout to increase insulin levels briefly and allow amino acids to enter muscle cells. Give your muscles the nutrients they need to repair and grow by consuming a snack with 30 grams of protein and at least 30-50 grams of carbs after a workout. A good dietary macronutrient ratio is 50% carb, 25% protein, 25% fats. Make sure you’re consuming enough calories for your activity level. Without adequate calories and nutrition, your body will enter a catabolic state.
Reduce Catabolic Effects: Get Adequate Sleep
Aim for at least 7 hours of sleep a night, preferably more. Even one night of inadequate sleep elevates cortisol levels. Higher cortisol levels can tip you over into a catabolic state. Lack of sleep also elevates appetite hormones like ghrelin that increase hunger. You also won’t be able to give strength training your best effort when you’re deprived of sleep. Getting enough sleep shouldn’t be a luxury – it’s a necessity.
The Bottom Line?
If your only goal is to build strength and lean body mass, too much cardio, especially without adequate nutrition, can put you in a catabolic state and make it difficult to reach your goal. Use these tips to avoid a chronic catabolic state and successfully reach your fitness goals.
Metabolism. Volume 43, Issue 7, July 1994, Pages 814–818.
Journal of Strength and Conditioning. 24(2): 79-84. (2011)
Elevated Hair Cortisol in Endurance Athletes. Psychoneuroendocrinology. September 2011.
Charles Poliquin “How to Counter the Many Negatives of Aerobic Training”
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