A physiologist is a scientist or healthcare professional who studies how the body works, from the behavior of individual cells to the coordinated function of entire organ systems. The field spans a wide range of specializations, so the day-to-day work of one physiologist can look very different from another’s. Some spend their careers in research labs investigating molecular processes, while others work directly with patients in hospitals or fitness centers.
What Physiologists Actually Study
Physiology is the branch of biology focused on understanding the mechanisms of living things. Physiologists study every aspect of how human and animal bodies function: how cells communicate, how organs coordinate, and how the whole organism responds to its environment. Some focus at the microscopic level, examining how individual proteins behave inside a single cell. Others zoom out to study how tissues, organs, and systems interact to keep a complex organism running.
This breadth is what makes the field so varied. A physiologist might specialize in how the heart pumps blood, how muscles generate force, how the lungs exchange gases, or how the brain processes signals. The common thread is always the same question: how does this biological system work, and what happens when it doesn’t?
Types of Physiologists
The term “physiologist” covers several distinct career paths. The most common ones you’ll encounter are exercise physiologists, clinical physiologists, and research physiologists.
Exercise physiologists work with people to improve health through physical activity. They run fitness and stress tests, design exercise programs for preventive care or injury recovery, and often focus on clients with chronic diseases, particularly around cardiovascular health and body composition. They typically work in hospitals, rehabilitation centers, fitness facilities, or corporate wellness programs.
Clinical physiologists work in hospital settings using specialized equipment to diagnose and monitor patients. Cardiac physiologists, for example, work in cardiology departments using high-tech diagnostic equipment to assess patients with heart problems and offer expert guidance to doctors. Other clinical physiologists specialize in lung function, sleep disorders, or neurological testing.
Research physiologists work in university or pharmaceutical labs, designing experiments to understand biological processes at a deeper level. Their work might involve studying how a disease disrupts normal cell function or testing how a new compound affects organ performance. These roles typically require a graduate degree, often a PhD.
Tools and Diagnostic Tests
Physiologists use a range of equipment depending on their specialty. Exercise and clinical physiologists commonly work with tools like metabolic carts, which measure your maximal aerobic capacity (VO2 max) by analyzing the gases you breathe in and out during intense exercise. This test reveals how efficiently your heart, lungs, and muscles use oxygen, and it’s a gold-standard measure of cardiovascular fitness.
Body composition is another major area of assessment. Physiologists use bioelectrical impedance devices that send a small electrical signal through your body to estimate muscle mass, fat percentage, visceral fat, and water content. Simpler tools like skinfold calipers measure fat at specific body sites. Blood pressure cuffs, pulse oximeters for tracking blood oxygen levels, and heart rate monitors with chest straps round out the typical toolkit.
In hospital settings, cardiac physiologists operate electrocardiogram (EKG) machines, echocardiography equipment, and other imaging tools to evaluate heart rhythm and structure. Respiratory physiologists use spirometry devices that measure how much air you can move in and out of your lungs, and how quickly.
Education and Certification
The education required depends on which type of physiologist you want to become. For exercise physiology, the American College of Sports Medicine (ACSM) offers a tiered certification system that maps to different education levels.
- Certified Exercise Physiologist (ACSM-EP): Requires a bachelor’s degree or higher in exercise science. These professionals work with healthy clients and those with medically controlled conditions to establish safe exercise and lifestyle plans.
- Certified Clinical Exercise Physiologist (ACSM-CEP): Requires either a bachelor’s degree in exercise science with 1,200 hours of hands-on clinical experience, or a master’s degree in clinical exercise physiology with 600 hours of clinical experience. This credential is geared toward working with higher-risk populations in medical settings.
Research physiologists typically hold a master’s or doctoral degree in physiology, biology, or a related field. Clinical physiologists working in hospitals (like cardiac or respiratory physiologists) usually complete specialized undergraduate or postgraduate programs specific to their area, with requirements varying by country.
How Physiologists Differ From Physical Therapists
This is a common point of confusion. Both professions involve exercise and working with patients, but the focus is different. Exercise physiologists design fitness and stress-testing programs, concentrating on improving cardiovascular health, body composition, and chronic disease management. Physical therapists diagnose and treat physical conditions using hands-on care and exercise prescription, with a primary focus on rehabilitation from injury, pain reduction, and restoring mobility.
In practical terms, you’re more likely to see a physical therapist after a knee surgery or a car accident, and more likely to see an exercise physiologist if you have diabetes, heart disease, or obesity and need a structured, safe exercise program. Physical therapists also require a doctoral-level degree (DPT), while exercise physiologists can practice with a bachelor’s degree and certification.
Job Outlook and Pay
For exercise physiologists in the United States, the median annual salary was $58,160 as of May 2024, according to the Bureau of Labor Statistics. Employment in the field is projected to grow 9 percent from 2024 to 2034, which is significantly faster than the average for all occupations. This growth reflects increasing demand for preventive health services and chronic disease management through exercise-based interventions.
Salaries for clinical physiologists working in hospital settings and research physiologists with advanced degrees tend to be higher, though exact figures vary widely by specialty, location, and experience level. Cardiac physiologists and those with doctoral degrees in research positions generally earn more than the exercise physiology median.