The Pros and Cons of Cardio During Mass Gaining Phases (WITH practical recommendations for once)

Summary

Lyle McDonald discusses whether cardio is useful during a muscle-gaining phase. His main point is that it depends on how cardio is done: a modest amount of low- to moderate-intensity activity may help, while excessive or very strenuous cardio can interfere with recovery and muscle-gain training.

Potential Benefits

• May support recovery: Easy aerobic activity can encourage blood flow between workouts.
• Can maintain fitness and work capacity: Better aerobic fitness may help with recovery between lifting sets and completing workouts without becoming overly winded.
• May help people with low appetites eat enough: Cardio could stimulate appetite for some people, though McDonald says the evidence is mixed and the effect varies.
• May preserve familiarity with aerobic exercise: This could make it easier to add cardio gradually when transitioning from bulking to dieting.
• Is not a reliable fix for excessive calorie intake: McDonald recommends keeping the calorie surplus modest rather than trying to offset overeating with exercise.

Possible Drawbacks

• For people who already struggle to eat enough, cardio may use calories that could otherwise support muscle gain.
• Too much cardio—especially alongside high-volume weight training—can add fatigue and impair recovery.
• Combining endurance and strength training may sometimes interfere with strength or muscle gains. McDonald emphasizes that the effect depends on the activity’s frequency, intensity, duration, and timing.
• He cautions against abruptly adding a large amount of cardio while dieting, particularly if training volume and recovery are not adjusted. He argues that this combination can contribute to muscle loss.

Practical Recommendations for Gaining Muscle

• Frequency: Aim for about three sessions per week, which McDonald describes as a reasonable minimum for fitness benefits.
• Duration: Do 20–30 minutes per session. Up to 45 minutes is acceptable if time and recovery allow; he sees little reason to go longer for this purpose.
• Intensity: Keep most sessions easy or moderate:
  • Low intensity: Very easy effort, such as brisk walking or easy cycling.
  • Moderate intensity: A noticeable but manageable effort—challenging, but not exhausting.
  • Talk test: Comfortable conversation suggests low intensity; short, interrupted conversation suggests moderate intensity; being able to speak only a word or two indicates effort that is likely too hard for his recommendations.
  • Heart-rate figures mentioned in the video are approximate and vary by person. McDonald favors perceived effort over generic heart-rate formulas.
• Activity type: Choose low-impact options such as a stationary bike, elliptical, stepper, or rowing machine. McDonald strongly advises against running during a bulking phase, citing its impact and recovery demands.
• Avoid high-intensity cardio and intervals when the primary goal is gaining muscle, according to McDonald, because they can be demanding to recover from and may add fatigue—especially for the legs.
• Increase cardio gradually when transitioning from a bulk to a diet rather than suddenly introducing long or strenuous sessions.

Presenters and Sources Mentioned

• Presenter: Lyle McDonald
• People and frameworks referenced: Gunnar Borg and the Borg perceived-exertion scale; John Parrillo; the FITT framework (frequency, intensity, time, type); and historical concurrent-training research attributed in the subtitles to “Gickson,” likely an auto-caption error.