Squats drive your heart rate and oxygen consumption surprisingly high, sometimes rivaling what you’d see during intense running, but that alone doesn’t make them “cardio” in the way most people use the word. A study measuring five sets of barbell back squats found that oxygen uptake climbed to roughly 100% of participants’ predetermined VOâ‚‚ max, with heart rates reaching about 90% of maximum by the fifth set.1PubMed Central. Cardiorespiratory and aerobic demands of squat exercise Those numbers look like vigorous aerobic exercise on paper. But what’s happening inside the muscle tells a different story, one that explains why squats can leave you gasping for air without delivering the same cardiovascular training effect as a long run.
Heart Rate and Oxygen Numbers During Squats
The most detailed look at the cardiorespiratory cost of squatting comes from research that had trained young men perform five sets of back squats at 70% of their one-rep max. By the fifth set, average heart rate hit about 175 beats per minute, or roughly 90% of their measured maximum. Oxygen consumption peaked at about 48 ml/kg/min, which corresponded to nearly 100% of their VOâ‚‚ max as measured on a separate treadmill test.1PubMed Central. Cardiorespiratory and aerobic demands of squat exercise In other words, by the time they finished their last set, their cardiovascular system was working about as hard as it possibly could.
Interestingly, the stronger participants reached even higher relative oxygen consumption. Those in the high-strength group hit about 108% of their pre-determined VOâ‚‚ max during squats, compared to roughly 94% in the lower-strength group. Averaged across all five sets, the stronger lifters were working at about 98% of VOâ‚‚ max while the weaker group averaged around 86%.1PubMed Central. Cardiorespiratory and aerobic demands of squat exercise This makes intuitive sense: a stronger person can move heavier absolute loads, which means more total muscle mass working against more resistance, placing a larger demand on the heart and lungs to deliver oxygen.
A separate study looking at squats performed at lighter loads confirmed that both heart rate and oxygen consumption climb progressively across successive sets. When participants squatted at 50% of their one-rep max, heart rate rose from about 93 beats per minute in the first set to roughly 105 by the third. At 75% of one-rep max, it climbed from around 83 to about 87 across three sets. Oxygen consumption followed a similar upward drift at both intensities.2Nature. Effects of squat training on energy expenditure, oxygen consumption, and heart rate in young healthy adults So even at moderate weights, squats create a cardiovascular demand that accumulates rather than staying flat.
Why a Pounding Heart Doesn’t Automatically Mean Cardio
Here is where the picture gets more complicated. When most people ask whether squats “count as cardio,” they’re really asking whether squats train the aerobic energy system the same way running, cycling, or swimming does. The short answer is: not in the same proportion. During traditional aerobic exercise at a steady pace, the vast majority of energy comes from oxygen-dependent pathways. During heavy squats, the balance shifts dramatically toward anaerobic metabolism, even though your heart is pounding.
Research measuring the split between aerobic and anaerobic energy during resistance exercises at 80% of one-rep max found that the half squat relied on anaerobic metabolism for about 87% of its energy.3PubMed Central. Aerobic and Anaerobic Energy During Resistance Exercise at 80% 1RM That’s a striking number. Even though oxygen consumption was measurably elevated, the muscles were getting the vast majority of their fuel from systems that don’t require oxygen in real time. For context, the bench press in the same study was about 78% anaerobic, and the lat pulldown about 72%. The squat was the most anaerobic of the bunch, likely because the loads are heavier and the muscle mass involved is larger, meaning the demand outstrips what the aerobic system can supply in the moment.
This distinction matters because aerobic adaptations, the kind that improve your resting heart rate, expand the heart’s stroke volume, grow new capillaries in muscle, and boost endurance, are driven primarily by sustained aerobic demand. Your heart rate being high during squats tells you your cardiovascular system is under stress, but much of that stress comes from spiking blood pressure, straining against a heavy load, and recovering between reps rather than from the kind of continuous, moderate-intensity work that most efficiently improves aerobic fitness.
Heart Rate as a Misleading Fitness Tracker During Lifting
If you’ve ever worn a heart rate monitor during a squat session and seen it flash “cardio zone” or “peak zone,” you’ve encountered one of the most common sources of confusion. Heart rate is used across fitness apps and gym equipment as a proxy for exercise intensity and calorie burn, and it works reasonably well for steady-state aerobic activities. During resistance exercise, though, heart rate becomes an unreliable narrator.
A study comparing circuit training (which includes squats and similar exercises) to treadmill running at matched heart rates found that total energy expenditure was substantially lower during the circuit training, even though participants reported that the circuit felt harder. At the same heart rate and the same duration, the treadmill session burned meaningfully more calories.4The Journal of Strength & Conditioning Research. Comparison of Acute Energy Expenditure and Rating of Perceived Exertion in Equivalent Bouts of Circuit Training and Treadmill Running The researchers specifically noted that although circuit training pushed heart rates into aerobic training zones and felt more strenuous, it was not associated with greater calorie expenditure. So using heart rate to judge whether your squat session “counts” as cardio can genuinely mislead you.
Why does heart rate spike during squats even when oxygen-based energy production is lower? Several factors inflate the number. The Valsalva maneuver, where you brace your core and hold your breath during the hard part of the rep, dramatically increases intra-abdominal and intra-thoracic pressure. That compresses blood vessels, transiently drops the amount of blood the heart can eject, and triggers a compensatory rise in heart rate. Blood pressure shoots up. The heart works harder per beat, not because it’s delivering more oxygen to working muscles the way it does during a jog, but because it’s pushing against much higher resistance in the vascular system. On top of that, the isometric tension of stabilizing muscles and the hormonal stress response both contribute to elevated heart rate independently of aerobic demand.
How Breathing Technique Changes the Cardiovascular Picture
The way you breathe during squats has a measurable effect on how hard your heart works. A study on healthy women compared breath-hold squats (the common bracing technique) to continuous breathing across a range of intensities. Holding your breath during reps increased heart rate by 2–5%, cardiac output by 3–8%, and systolic blood pressure by 16–23% compared to continuous breathing. The rate-pressure product, a rough measure of how much work the heart is doing, jumped by 20–30% with breath holding.5PubMed Central. Breathing technique-dependent acute cardiopulmonary responses during squats in healthy females
At the same time, actual oxygen uptake dropped by 11–15% during breath-hold reps, and minute ventilation (total air moved through the lungs) fell by 16–17%. After the set, there was an overshoot, where oxygen consumption and breathing temporarily spiked above what would be expected, as the body played catch-up.5PubMed Central. Breathing technique-dependent acute cardiopulmonary responses during squats in healthy females This is a perfect illustration of why heart rate alone is a poor gauge of aerobic work during squats. The heart is beating faster and blood pressure is spiking, yet the lungs are actually taking in less oxygen. The cardiovascular strain is real, but it doesn’t reflect an increase in aerobic energy production. It reflects increased mechanical stress on the system.
This also carries a practical message for people with cardiovascular risk factors. Even at low-to-moderate squat intensities, the breath-hold technique produced a meaningful cardiovascular load. If you have high blood pressure or heart disease, your doctor’s advice to avoid heavy straining during lifting isn’t arbitrary, and it’s separate from whether you’re getting an “aerobic benefit.”
Why Squats Stand Out Among Resistance Exercises
Not all lifts stress the heart equally, and squats are on the high end precisely because of how much muscle they recruit. Research comparing multi-joint exercises like the leg press to single-joint exercises like leg extensions found that multi-joint movements produced larger increases in systolic blood pressure, diastolic blood pressure, and overall hemodynamic load, regardless of whether the person was a trained lifter or a novice.6Journal of Human Growth and Development. Multi-joint exercise promotes larger hemodynamic overland regardless of strength training experience The researchers concluded that exercise selection had a greater influence on the acute cardiovascular response than the participant’s training background.
Squats involve the quadriceps, hamstrings, glutes, spinal erectors, and a host of stabilizing muscles from the calves to the upper back. When a large percentage of total body musculature contracts simultaneously against a heavy load, the demand for blood flow surges. But the contracting muscles also compress their own blood vessels, increasing peripheral resistance and forcing blood pressure higher. It’s a cardiovascular tug-of-war that doesn’t exist to nearly the same extent during, say, a bicep curl or a running stride. This is partly why squats generate that breathless, racing-heart feeling more reliably than most other lifts.
The Oxygen Measurement Problem
Researchers studying squats face a genuine measurement challenge. Standard gas exchange analysis, the gold-standard way to measure aerobic energy use, works best when the body reaches a steady state where oxygen supply matches demand. During a set of heavy squats, that steady state never arrives. A set might last 15–30 seconds, and oxygen uptake lags behind actual metabolic demand by several seconds. The muscles burn through stored high-energy phosphates and produce lactate faster than oxygen delivery can keep pace.
This means that oxygen consumption measured during the set underestimates the total metabolic cost, while the elevated oxygen consumption measured after the set (often called excess post-exercise oxygen consumption, or EPOC) catches some of what was “borrowed” anaerobically.2Nature. Effects of squat training on energy expenditure, oxygen consumption, and heart rate in young healthy adults Research on how different set structures affect energy system contribution has confirmed that traditional continuous sets push the lactate-based anaerobic system harder, while formats with short intra-set rests shift the balance back toward the alactic and aerobic systems.7PubMed Central. Intra-set rest preserves barbell velocity during a free-weight back squat exercise by shifting energy system contribution This matters if you’re trying to program squats for a cardiovascular stimulus: the structure of the set, how many reps, how long you rest, whether you pause mid-set, all influence which energy system does the heavy lifting.
Can You Actually Train Cardio Fitness With Squats?
Given that squats do demand high oxygen consumption and elevated heart rates, is it possible to structure squat training in a way that genuinely improves aerobic fitness? The evidence suggests: partially, and with caveats. The fact that five heavy sets of squats can push oxygen consumption to near-maximal levels means the cardiovascular system is clearly being stressed.1PubMed Central. Cardiorespiratory and aerobic demands of squat exercise Stress is the prerequisite for adaptation. But the nature of that stress, intermittent bursts with rest intervals rather than sustained output, resembles high-intensity interval training more than steady-state cardio.
If your goal is to improve your VOâ‚‚ max or lower your resting heart rate, squats alone are probably an inefficient route compared to actual aerobic exercise. Running, cycling, rowing, and swimming let you sustain aerobic demand for much longer periods, driving the specific adaptations (increased stroke volume, mitochondrial density, capillarization) more directly. However, if you’re someone who already does resistance training and wants to extract some cardiovascular benefit from it, choosing high-rep squat protocols with controlled rest periods pushes the needle more than, say, low-rep sets with five-minute rests. The lighter-load protocol at 50% of one-rep max produced more cumulative heart rate elevation across sets than the heavier protocol at 75%, partly because the sets last longer and demand more sustained muscular work.2Nature. Effects of squat training on energy expenditure, oxygen consumption, and heart rate in young healthy adults
High-rep squat sets, squat-based circuit training, and barbell complexes all sit in a middle zone that taxes both anaerobic and aerobic systems. They won’t replace dedicated cardio for someone training for a 10K, but they’re probably more cardiovascularly useful than most people give them credit for, especially for someone whose primary goal is general health rather than competitive endurance.
What Heavy Squatting Does to Your Blood Vessels Over Time
A separate question from acute cardiovascular demand is whether habitual heavy squatting changes your blood vessels for better or worse. The picture here is genuinely mixed. One study found that a high-intensity resistance training program increased central arterial stiffness and wave reflection in young healthy women, suggesting that heavy lifting might make the major arteries less elastic over time.8American Journal of Hypertension. Effects of High Intensity Resistance Training on Arterial Stiffness and Wave Reflection in Women That sounds alarming, since stiffer arteries are associated with higher cardiovascular risk.
However, a broader review of the literature across ages and training intensities concluded that while small increases in central arterial stiffness have been reported in some groups of younger men, resistance training overall may not significantly affect arterial stiffness, and lower-intensity resistance training might even decrease systemic stiffness in young healthy adults.9PubMed. Impact of high- and low-intensity resistance training on arterial stiffness and blood pressure in adults across the lifespan: a review A four-week intervention of high-intensity resistance training in young active women found no significant changes to central arterial stiffness, wave reflection, or heart rate variability at all.10PubMed. Central arterial stiffness, wave reflection, and heart rate variability following 4-week high-intensity resistance training intervention in young active women
The disagreement across studies probably reflects differences in training duration, intensity, participant characteristics, and measurement techniques. The safest takeaway is that short-term or moderate-volume resistance training, including squats, is unlikely to harm your vascular health, and may even provide some benefit depending on the protocol. If you combine heavy lifting with regular aerobic exercise, the aerobic component likely offsets any small increases in arterial stiffness that heavy resistance training alone might produce.
Isometric Squats and Blood Pressure After the Workout
While barbell squats are the most commonly discussed variation, isometric wall squats, where you hold a squat position against a wall without moving, have attracted research attention for a completely different cardiovascular reason: what happens to blood pressure after you finish. A study in older women with high blood pressure found that a single session of isometric wall squats held for cumulative bouts totaling 12 minutes produced a clinically meaningful blood pressure drop of roughly 8–10 mmHg in the hour following the exercise.11Journal of Hypertension. Dose–response effects of isometric wall squats on postexercise hypotension in older women with hypertension That post-exercise blood pressure reduction exceeded what is typically reported with isometric handgrip exercise, another well-studied isometric modality. Shorter protocols totaling about eight minutes didn’t produce the same effect, suggesting a dose threshold.
The researchers described this equipment-free protocol as a relevant option for managing blood pressure in older women. It’s an intriguing twist on the “are squats cardio?” question: the dynamic version pushes heart rate and blood pressure sharply upward during the exercise, while the isometric version appears to lower resting blood pressure afterward. Both are squats in name, but the physiological story and the potential cardiovascular benefit differ substantially. For someone managing hypertension under medical supervision, this kind of isometric squat work represents a genuinely different use case from heavy barbell training, one where the “cardio” benefit isn’t about aerobic fitness at all but about lasting changes in blood vessel tone after the session ends.