Isotonic and Isometric Exercise

The CDC recommends adults do at least 150 minutes of moderate-intensity aerobic exercise each week (or 75 minutes of vigorous-intensity aerobic activity each week) AND muscle strengthening activities on at least two days each week. These two categories can overlap if you’re doing a Pilates class that uses weights and raises your heart rate, or if you participate in the Absolution or Lower Body Conditioning group fitness classes at the SRC on campus, for example. It’s important to include muscle strengthening exercises into your routine. These exercises help you to maintain muscle tone, which helps to prevent a decrease in metabolism over time, and also increase bone strength and reduces calcium loss and risk of osteoporosis as you age, especially in women.

Two Categories of Muscle Strengthening Exercises

Isotonic Exercise

Isotonic exercises involve muscles contracting and shortening as they overcome resistance, with movement in the attached joint. Examples include lifting weights or even carrying groceries. These exercises build muscle strength and endurance but don't heavily impact the cardiovascular system, so your heart rate may or may not increase, depending on the weight.

Isotonic Exercise Examples

• Push-ups
• Pull-ups
• Crunches or sit-ups
• Dumbbell curls (biceps/triceps)
• Squats (keep knees behind toes)
• Russian twists
• Supermans (lay on stomach, lift chest/legs)
• Reverse crunches
• Burpees
• Bench presses

Isometric Exercise

Isometric exercises occur when a muscle contracts but doesn’t shorten because it can't overcome the resistance, and the joint doesn’t move. An example is when you're holding a squat or trying to lift a heavy weight but can’t move it. These exercises can raise your heart rate and are more taxing on the cardiovascular system, so they can't be done for as long or as frequently as isotonic exercises.

Isometric Exercise Examples

• Plank (forearm or full plank, keep body aligned)
• Wall-sit (hold for 1 minute)
• Squat holds (hold for at least 30 seconds)
• Side plank (extend top arm upward)
• Abdominal cross holds (hold for 30 seconds, switch sides)
• Tree pose (stand on one leg, hold for 30-60 seconds)
• Warrior two (hold lunge-like pose for 30 seconds on each side)
• Chair pose (sit back, arms extended, hold for 30 seconds)
• Push against a wall (hold for 30 seconds)

Note: Isometric exercises can raise blood pressure, so check with your doctor if you have high blood pressure. Remember to include both types of exercises at least twice a week for balanced strength training.