Key Takeaways
- Strength training preserves muscle mass and bone density, which decline naturally with age.
- Cardio improves heart health, lung capacity, and metabolic efficiency.
- The American College of Sports Medicine recommends both modalities for healthy adults.
- Combining the two does not require doubling training time — smart scheduling makes both achievable.
- Neither type of exercise alone delivers the full range of health benefits that both together provide.
Concurrent Training
Concurrent training refers to combining both resistance (strength) training and aerobic (cardio) exercise within a regular fitness routine. Rather than choosing one or the other, adults who practice concurrent training develop muscular strength and cardiovascular endurance side by side. This approach is widely supported by exercise science organizations as the most complete strategy for long-term health.
In exercise physiology, "concurrent training" describes the pairing of resistance and aerobic modalities, sometimes within the same session or across a weekly schedule. Research explores how sequencing and volume affect adaptations in each domain.
Two Systems, Two Distinct Adaptations
Resistance training and aerobic exercise each target different physiological systems — and that's precisely why both matter. When you lift weights or perform bodyweight resistance work, you stimulate skeletal muscle fibers to grow stronger and denser. Over time, this also stresses bones, prompting them to maintain or increase their mineral density. These adaptations become increasingly important as adults age, because muscle mass and bone density both decline naturally after the mid-30s without deliberate effort to preserve them.
Cardio, by contrast, trains the cardiovascular and pulmonary systems. Regular aerobic activity strengthens the heart muscle, improves the efficiency of oxygen delivery to working tissues, lowers resting heart rate, and supports healthy blood pressure and cholesterol levels. It also enhances the body's ability to use fat as fuel and improves insulin sensitivity — a key factor in metabolic health.
Neither modality delivers the other's benefits in any meaningful way. Running will not meaningfully build muscle mass. Lifting weights will not train VO₂ max — the measure of your body's maximum oxygen-use capacity — to the degree that sustained aerobic work does. This is why the cardio-vs.-strength debate is largely a false choice: the real question is how to structure both.
150 min
Weekly moderate aerobic activity recommended for adults
The American College of Sports Medicine and American Heart Association both recommend at least 150 minutes of moderate-intensity cardio per week for healthy adults.
2+ days
Resistance training sessions recommended weekly
ACSM guidelines specify at least two resistance training sessions per week targeting all major muscle groups for adults.
3–8%
Muscle mass lost per decade after age 30 without resistance training
Research estimates that adults lose between 3% and 8% of muscle mass per decade from the 30s onward, a process that accelerates with age — a primary driver for resistance training recommendations.
What the Guidelines Actually Say
The American College of Sports Medicine (ACSM) and the American Heart Association (AHA) both recommend that healthy adults engage in at least 150 minutes of moderate-intensity aerobic activity per week — or 75 minutes of vigorous-intensity activity — alongside resistance training at least two days per week targeting all major muscle groups. These are minimums, not ceilings.
Importantly, meeting both guidelines does not require doubling your weekly time commitment. A well-designed schedule integrates both modalities across the same week, often with some sessions combining elements. For practical guidance on structuring that schedule, see building a weekly exercise routine that balances strength and cardio.
You Don't Need to Choose a "Main" Modality
Many adults assume they must prioritize either cardio or strength and fit the other in around it. In practice, both can be treated as equally important pillars of a weekly schedule. Even two resistance sessions and three moderate cardio sessions per week — spread across five days — meets major guidelines without requiring daily training.
How Age Changes the Equation
Adults in their 20s and 30s may get away with an imbalanced routine for a while. But as the decades progress, the stakes shift. Sarcopenia — the age-related loss of muscle mass and strength — can begin as early as the mid-30s and accelerates after 60 if unchecked. Alongside it, reduced cardiovascular fitness raises risk for heart disease, the leading cause of death in the United States.
Resistance training becomes more urgent, not less, as adults age. Yet cardiovascular fitness remains equally critical for functional independence and disease prevention. The relationship between the two modalities over a lifetime is explored further in strength training across the lifespan.
Special populations — including older adults, pregnant individuals, and those managing chronic conditions — should consult a qualified healthcare provider before starting or significantly modifying any exercise program.
Managing Both Without Overtraining
One legitimate concern about combining modalities is the risk of doing too much too soon. Overtraining — accumulating more training stress than the body can recover from — is real, particularly for adults balancing fitness with work, family, and inadequate sleep.
The solution is strategic programming rather than avoidance. High volumes of endurance work can interfere with muscle-building adaptations — a well-documented phenomenon in exercise science. Understanding when cardio undermines strength gains helps adults make smarter decisions about sequencing, intensity, and recovery.
Practical strategies include: separating long cardio sessions from heavy resistance training by several hours or placing them on different days; keeping at least one full rest or active recovery day per week; and building volume gradually rather than jumping to high workloads. Adequate sleep and nutrition — particularly protein intake to support muscle repair — are non-negotiable parts of the recovery equation.
The Bottom Line
Strength training and cardio are not rivals competing for space in a limited schedule. They are complementary tools that address different dimensions of health — muscular strength and endurance, cardiovascular efficiency, metabolic function, bone density, and functional capacity across the lifespan. Adults who develop both are better positioned for long-term health than those who develop only one.
For a broader overview of how these training types interact and how to build a sustainable routine, this complete overview of strength and cardiovascular fitness is a useful next step.
This article is for general informational and educational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before beginning any new exercise program, particularly if you have an existing health condition or have been inactive for an extended period.