There are four fundamental kinds of exercise: endurance (cardio), strength, balance, and flexibility. Each one targets a different aspect of fitness, and the best routine includes some combination of all four. The World Health Organization recommends 150 to 300 minutes of moderate-intensity aerobic activity per week, or 75 to 150 minutes of vigorous activity, plus at least two days of strength training.
Understanding what each type does and how they overlap helps you build a routine that actually fits your goals, whether that’s losing weight, building muscle, improving mood, or simply staying mobile as you age.
Endurance (Cardio) Exercise
Endurance exercise is anything that raises your heart rate and keeps it elevated for a sustained period. Walking, jogging, cycling, swimming, and dancing all count. This type of exercise strengthens your heart and lungs, reduces your risk of cardiovascular disease, lowers the chance of developing type 2 diabetes, and improves sleep quality.
Cardio falls into two broad categories based on intensity. Moderate-intensity activities like brisk walking or casual cycling feel like you’re working but can still hold a conversation. Vigorous-intensity activities like running or fast swimming push you hard enough that talking becomes difficult. Scientists measure intensity using a scale called METs: sedentary behavior sits at 1.0 to 1.5, moderate activity ranges from 3.0 to 5.9, and vigorous activity starts at 6.0 and above. Sweeping the floor, for instance, clocks in around 3.3 METs, placing it just inside moderate territory.
A common question is whether high-intensity interval training (HIIT) burns more fat than steady, moderate cardio. A systematic review of 11 randomized trials found no significant difference in body fat percentage between the two approaches. HIIT does burn more total energy per minute, but when researchers compared the two head to head, neither was superior for reducing body fat or abdominal visceral fat. Pick whichever style you’ll stick with consistently.
Strength Training
Strength exercise uses resistance, whether from dumbbells, machines, resistance bands, or your own body weight, to build and maintain muscle. Beyond aesthetics, it makes everyday tasks easier: carrying groceries, climbing stairs, getting up from a chair. Muscle mass also plays a protective role as you age, supporting joint stability and bone density.
How often you train each muscle group matters more than how long each session lasts. A meta-analysis published in Sports Medicine found that training a muscle group at least twice per week produces significantly more growth than training it once per week, even when total training volume is the same. Whether three times per week is better than two remains unclear, but twice is the minimum threshold for maximizing results. This means a three-day full-body routine or a four-day upper/lower split both work well, as long as each muscle gets hit at least twice in seven days.
Balance Training
Balance exercises strengthen the muscles that keep you upright, primarily in your legs and core. They’re critical for older adults: higher levels of physical activity reduce fall risk by 30% to 50%. The WHO recommends people over 65 do balance exercises on three or more days per week alongside their cardio and strength work.
Effective balance training doesn’t require special equipment. Tai chi, stepping drills, standing on one foot with eyes closed, walking heel to toe, and even certain video game platforms that challenge your stability have all been studied and shown benefits. The key is practicing movements that challenge your center of gravity in both static positions (standing still on an unstable surface) and dynamic ones (changing direction, stepping over obstacles). Even 50-minute sessions twice a week, using exercises that mimic real-life tasks where people feel unsteady, have shown measurable improvements in stability.
Flexibility and Stretching
Flexibility exercises improve your range of motion, the ability to bend, reach, twist, and look over your shoulder without strain. This matters for practical things like picking something up off the floor or backing a car out of a driveway. Stretching also supports recovery after other types of exercise by reducing muscle stiffness.
There are two main approaches, and timing matters. Dynamic stretching uses controlled movements like walking lunges, high knees, and leg swings to warm up muscles before activity. It raises body temperature and blood flow, which improves performance and reduces injury risk. Static stretching, where you hold a position for 30 seconds, is better suited for after a workout. Research has consistently found that static stretching before explosive activity can temporarily reduce muscle power, while dynamic stretching tends to maintain or even boost sprint and power performance.
A practical rule: dynamic stretches before you exercise, static stretches after.
Which Type Is Best for Mental Health
All exercise improves mood, but some types are particularly effective at increasing a protein in the brain that supports nerve cell growth and repair. This protein plays a central role in regulating mood and is often found at low levels in people with depression.
A network meta-analysis comparing multiple exercise types found that aerobic exercise was the most effective at raising levels of this protein in people with depression, followed closely by resistance training and yoga. Practices like qigong and mindfulness-based movement were less effective. If you’re exercising partly for your mental health, cardio, strength training, and yoga all offer meaningful benefits, and combining them likely amplifies the effect.
Low-Impact Options for Joint Pain
If joint pain or arthritis limits what you can do, low-impact exercise keeps stress on your joints low while still delivering cardiovascular and strength benefits. The Mayo Clinic identifies walking, stationary or recumbent cycling, elliptical trainers, swimming, and water aerobics as the best options. Water-based exercise is especially helpful because buoyancy supports your body weight, reducing the load on hips, knees, and ankles while still providing resistance.
The goal isn’t to avoid movement. Regular low-impact activity actually helps ease arthritis pain and stiffness over time by strengthening the muscles around affected joints and improving circulation to cartilage.
Putting It All Together
You don’t need four separate workout programs. Many activities overlap categories. Swimming builds endurance and provides some resistance training. Yoga improves flexibility, balance, and strength simultaneously. A brisk walk on uneven terrain challenges your cardiovascular system and your balance at the same time.
A simple weekly framework that meets current guidelines could look like this:
- 3 to 5 days: 30 to 60 minutes of moderate cardio (walking, cycling, swimming) or 15 to 30 minutes of vigorous cardio (running, HIIT)
- 2 to 3 days: strength training covering all major muscle groups
- 3 or more days (especially over 65): balance exercises like tai chi, single-leg stands, or stepping drills
- Daily or post-workout: 5 to 10 minutes of stretching
The best kind of exercise is ultimately the kind you do regularly. If you enjoy it, you’ll keep doing it. Start with what feels manageable, build consistency, and layer in variety over time.