Weights or cardio first? The evidence-based order that gets men results faster

If you lift and do cardio in the same session, the order can change what you get out of the workout. Here is what the research says about doing weights or cardio first, and how to set up your week for muscle, endurance, and long-term health.

The relationship

Doing strength training and cardio in the same workout, often called concurrent training, can be a smart time saver for busy men. Concurrent training means you combine resistance exercise and aerobic training in one program or session. The catch is that pairing them too closely can slightly reduce performance or blunt some strength and muscle gains in some situations.^[1]

This is why “weights or cardio first” is not just gym trivia. If your priority is endurance, research and coaching practice generally favor doing cardio before weights, so the quality of your aerobic work stays high. If your priority is building muscle and strength, doing weights first usually wins, because you can lift heavier and complete more high-quality sets.^[1]

For general fitness and long-term health, the order matters less than consistency. Still, for most men training with challenging loads, there is a practical safety argument for weights first: heavy lifting demands coordination and bracing, and fatigue can degrade technique. The higher the load, the higher the stakes.

How it works

Concurrent training and the “interference effect”

The interference effect is the observed tendency for endurance-focused training to reduce strength or hypertrophy gains when the total program is not designed well.^[1] Hypertrophy means muscle growth from training, mainly through adding contractile proteins and increasing muscle fiber size.

Mechanistically, researchers describe partly competing signals, including AMPK and mTOR. AMPK is a cellular “fuel gauge” that rises when energy demand is high, while mTOR is a growth pathway that supports muscle protein synthesis after lifting.^[2]

Fatigue, glycogen, and why cardio before weights can lower your numbers

Endurance work done first can reduce how much volume you can lift, especially for lower-body sessions, because of local muscular fatigue and reduced glycogen. Glycogen is stored carbohydrate in muscle that helps power hard efforts.^[2]

Human studies on exercise order show that doing endurance before resistance can reduce subsequent strength performance and total quality work, which matters because training volume is a key driver of hypertrophy.

Neuromuscular precision and injury risk at heavy loads

Heavy resistance training relies on high motor unit recruitment and tight coordination. A motor unit is a nerve and the muscle fibers it controls, and recruiting more of them helps you produce force. Fatigue can reduce power output and degrade balance and landing mechanics, which is one reason coaches avoid placing the most technical, heaviest lifts after exhaustive conditioning.^[3]

This does not mean cardio after weights is “dangerous.” It means that if you are choosing between weights or cardio first on a day you plan to squat heavy, lifting first is often the safer bet for men who train close to their limits.

Specificity: train the priority first

Specificity is the principle that your body adapts most to the stimulus you prioritize. If your goal is endurance performance, doing cardio first can preserve pace, power, and time-in-zone, which are key inputs for improving aerobic fitness.

If your goal is size and strength, doing weights first helps you keep load, reps, and rest periods where they need to be for progressive overload. Progressive overload means gradually increasing training demand over time to drive adaptation.^[1]

Conditions linked to it

Exercise order is not a medical diagnosis, but it can influence outcomes that matter to men’s health:

• Loss of muscle mass and strength with aging: Resistance training is a frontline tool for preserving lean mass, power, and insulin sensitivity in men as they get older. If cardio first repeatedly lowers lifting quality, you may undershoot the resistance stimulus you need.^[1]
• Cardiometabolic risk: Men with higher waist circumference, elevated blood pressure, or prediabetes often benefit from combining resistance training with aerobic work. The order is usually less important than total weekly dose and adherence, but protecting lifting quality still matters for long-term body composition.^[4]
• Overuse injuries: High-impact cardio such as running layered onto heavy leg training can raise total tissue stress. Modality selection, volume, and recovery often matter more than the simple question of weights or cardio first.^[1]
• Low energy availability and hormone disruption in endurance-heavy programs: Some endurance-trained men can develop chronically low testosterone when training volume is very high and fueling is inadequate. Hypogonadism means clinically low testosterone with symptoms.

If symptoms suggest testosterone deficiency, guidelines support evaluation with morning labs. Meta analyses indicate that symptomatic men with total testosterone below 350 ng/dL, about 12 nmol/L, are most likely to benefit from TRT. If total testosterone is borderline, measure free testosterone; values below 100 pg/mL, about 10 ng/dL, support hypogonadism. In practice, use 350 ng/dL for total or 100 pg/mL for free as decision thresholds when symptoms persist.^[5]

Limitations: Not every study finds meaningful interference, and effects depend on training status, total volume, intensity, exercise selection, and recovery. Many trials are short, and “real life” training varies widely.^[2]

Symptoms and signals

If you are unsure whether cardio or weights first is working for you, watch for patterns like these:

• Strength stall: Your big lifts plateau for 6 to 8 weeks despite consistent effort and a sensible program.
• “Cardio tax” on lifting: Your squat, deadlift, or leg press numbers drop noticeably when you run or do intervals first.
• Form breaks down earlier: You feel shaky, rushed, or sloppy on heavy sets, especially after hard cardio.
• Lingering soreness: DOMS, delayed onset muscle soreness, lasts longer than 48 to 72 hours and keeps recurring. DOMS is post-exercise muscle pain that peaks a day or two after training.
• Recovery red flags: Resting heart rate trends up, sleep quality drops, or you feel persistently flat.
• Possible hormonal signal in men: Low libido, fewer morning erections, or unexplained fatigue during high training volume, especially with aggressive dieting. These are not proof of low testosterone, but they justify a conversation with a clinician.^[5]

What to do about it

Most men do not need a perfect plan. They need a clear priority, a repeatable structure, and a way to adjust. Use this 1-2-3 setup to decide “weights or cardio first” without overthinking it.

1. Step 1: choose the goal for the next 8 to 12 weeks, then put it first
   • Build muscle or get stronger: Do weights first, then add low to moderate intensity cardio after, or on a separate day.^[1]
   • Improve endurance performance: Do cardio first on key running, cycling, or rowing days, and lift after with lower volume, or lift on alternate days.
   • General fitness and longevity: If combining in one session, default to weights first because technique and load control matter most when you are fresh. Then finish with zone 2 cardio.

   Zone 2 is steady cardio at an intensity where you can speak in full sentences but would not want to sing. HIIT, high-intensity interval training, is repeated hard efforts with recovery periods. Weekly targets often used in public health guidance include at least 150 minutes per week of moderate intensity aerobic activity plus at least two strength sessions.^[4]

2. Step 2: design the session to reduce interference
   • Keep hard cardio away from heavy leg lifting: If you want HIIT, place it on an upper-body lift day, a separate day, or after lighter lower-body work.^[1]
   • Choose lower-impact cardio when lifting is the priority: Cycling and incline walking usually create less muscle damage than hard running, which may reduce the interference effect for hypertrophy.^[1]
   • Separate sessions when you can: If your schedule allows, lifting and cardio on different days, or separated by hours, is a common strategy to protect performance while keeping total weekly volume high.^[2]
3. Step 3: monitor the right metrics and adjust
   • Track performance: Log your top sets, reps, and RPE. RPE is rate of perceived exertion, a 1 to 10 scale of effort.
   • Fuel for the work: Men who lift and do cardio need enough protein and carbohydrates to recover and keep training quality high. Protein supplementation can improve resistance training gains when overall intake is insufficient.^[6]
   • Progress cardio like you progress weights: Add minutes, intervals, or intensity gradually. HIIT is effective, but it is also more fatiguing, so use it deliberately.

Myth vs fact

• Myth: “Cardio is catabolic, so it kills muscle no matter what.” Fact: Interference is real in some setups, but it depends on dose, intensity, modality, and recovery. Many men can build muscle while doing cardio when programming is smart.^[1],[2]
• Myth: “You must always separate cardio and weights by days.” Fact: Same-day training can work well. Separating sessions is a tool for higher volumes or higher performance goals, not a rule for everyone.^[2]
• Myth: “HIIT after heavy squats is the best fat-loss hack.” Fact: HIIT is effective, but stacking it after maximal lower-body lifting can crush recovery. Many men do better with zone 2 after weights and HIIT on another day.
• Myth: “If you do cardio first, you are wasting your gym time.” Fact: If endurance is the priority, doing cardio first is often the right call. The best order is the one that supports your primary adaptation.

Bottom line

If you are deciding between weights or cardio first, put the goal that matters most to you at the front of the session. For muscle and strength, lift first. For endurance performance, do cardio first. For general health, consistency wins, but weights first is often the safest and most repeatable choice for men lifting heavy.

References

1. Wilson JM, Marin PJ, Rhea MR, et al. Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. Journal of strength and conditioning research. 2012;26:2293-307. PMID: 22002517
2. Fyfe JJ, Bishop DJ, Stepto NK. Interference between concurrent resistance and endurance exercise: molecular bases and the role of individual training variables. Sports medicine (Auckland, N.Z.). 2014;44:743-62. PMID: 24728927
3. Gribble PA, Hertel J, Denegar CR, et al. The Effects of Fatigue and Chronic Ankle Instability on Dynamic Postural Control. Journal of athletic training. 2004;39:321-329. PMID: 15592604
4. Piercy KL, Troiano RP, Ballard RM, et al. The Physical Activity Guidelines for Americans. JAMA. 2018;320:2020-2028. PMID: 30418471
5. Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. The Journal of urology. 2018;200:423-432. PMID: 29601923
6. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British journal of sports medicine. 2018;52:376-384. PMID: 28698222