Many people tend to use aerobic training & cardio as a form of punishment instead of a useful tool. Why might cardio overkill be detrimental to your program progression?

Overdoing cardio can be create a mismatch between recovery abilities, energy demands, & physiological adaptations. Here are some of the common issues experienced when overdoing cardio. 

1. Muscle Loss (Catabolism)

• Excessive cardio — especially in a calorie deficit — can lead your body to break down muscle for fuel.
• This decreases strength, performance, and slows down your metabolism (muscle is metabolically active).

2. Hormonal Disruptions

• In women, excessive cardio can cause amenorrhea (loss of menstrual cycle) and reduced bone density.
• Men may see drops in testosterone, affecting mood, libido, and muscle-building ability.

3. Elevated Cortisol (Stress Hormone)

• Chronic cardio increases cortisol, especially if you’re not recovering or eating enough.
• High cortisol:
• Promotes fat storage, especially in the midsection.
• Impairs muscle recovery and sleep.
• Disrupts thyroid and sex hormones (e.g., estrogen, testosterone).

4. Slower Metabolism (Adaptive Thermogenesis)

• Your body may compensate for too much cardio by lowering non-exercise activity, hormone production, and even resting metabolic rate.
• End result: you burn fewer calories at rest, making fat loss harder.

5. Plateau or Regress in Fat Loss

• You might lose initial weight, but over time the body adapts:
• You burn fewer calories per session.
• Hunger increases, leading to overeating or bingeing.
• Your physique becomes "skinny fat" — lower scale weight, but poor body composition.

6. Mental Burnout + Poor Relationship with Exercise

• You may feel guilty or anxious if you skip cardio.
• Exercise shifts from something enjoyable to something compulsive.
• This can lead to overtraining syndrome, mental fatigue, or even injury.

7. Injury Risk + Overuse

• High-impact cardio (like running) done daily can lead to:
• Joint pain
• Tendonitis
• Stress fractures
• Chronic inflammation

What can be considered overkill?

• Doing 60+ minutes of intense cardio daily, especially without fueling or recovery.
• Prioritizing cardio over strength training when trying to build or preserve muscle. Muscle is your longevity organ. Aim to preserve it!
• Doubling up cardio in 24 hours consistently without rest.

Aim to fit in 3-5 sessions a week anywhere from 5-45 minutes depending on intensity. For those who are more advanced & have developed better refuel habits, more aerobic activity can be integrated (with proper refuel techniques ofcourse). Make sure you are pairing resistance training with your aerobic training days!!!!

Use cardio as a tool, not a punishment. Prioritize resistance training. Cycle cardio volume and intensity based on your goals and energy levels. Consider using HIIT sparingly (1–2x/week), especially if strength or muscle retention is a priority.

Peer review info:

Risk Category

Evidence & Findings

Muscle Catabolism & Loss

Elevated cortisol-to-testosterone ratio, plus inadequate energy intake, leads to breakdown of muscle tissue and worse body composition. (PMC)

Hormonal & Immune Dysregulation

Disrupted HPA and HPG axes result in lower reproductive hormones, increased inflammation (IL‑6, TNF‑α), oxidative stress, and neurotransmitter imbalances. (SAGE Journals, PMC, PubMed)

Performance Declines

VO₂max, strength, and endurance performance drop in overtrained athletes despite continuing similar training. Recovery may take weeks to months. (PubMed, PMC, PubMed)

Mood & Cognitive Effects

Psychological symptoms (fatigue, irritability, depression), plus altered EEG and cognitive function, are common in endurance athletes experiencing OTS. (SpringerOpen, SAGE Journals)

Cardiovascular & Hormonal Risks in Elite Athletes

Structural heart changes and chronically lowered testosterone levels have been documented in veteran endurance athletes. (Wikipedia, Wikipedia)