Physical Activity Types, Variety, and Mortality: A Dinner Table Summary
Study Link: Han H, et al. BMJMED 2026;5:e001513. doi:10.1136/bmjmed-2025-001513
Executive Summary
A 30-year study of over 111,000 healthcare professionals found that most types of exercise—walking, jogging, running, tennis, weight training, and climbing stairs—were linked to living longer, with benefits plateauing at certain exercise levels rather than increasing forever. The surprise finding: people who mixed up their exercise routines with multiple types of activities lived 19% longer than those who stuck to just one or two activities, even when both groups exercised the same total amount. In other words, variety matters almost as much as volume when it comes to exercise and longevity.
The Research Team
Lead Authors:
- Han Han and Jinbo Hu (co-first authors) – Department of Nutrition, Harvard T.H. Chan School of Public Health
- Yang Hu and Qi Sun (co-senior authors) – Harvard T.H. Chan School of Public Health
Other Contributors:
- Dong Hoon Lee – Harvard and Yonsei University (South Korea)
- Yiwen Zhang – Harvard T.H. Chan School of Public Health
- Edward Giovannucci, Meir Stampfer, Frank Hu – Senior Harvard researchers in epidemiology and nutrition
Institutions:
- Harvard T.H. Chan School of Public Health (Boston)
- Brigham and Women's Hospital and Harvard Medical School
- Chongqing Medical University (China)
- Yonsei University (South Korea)
Conflicts of Interest
Funding Sources:
- National Institutes of Health (multiple grants totaling millions)
- American Cancer Society (for Dr. Giovannucci's position)
Financial Conflicts:
- None declared – All authors completed disclosure forms and reported no financial relationships with organizations that might benefit from this research
Key Point: This is publicly funded academic research with no apparent industry influence, which strengthens confidence in the findings.
What They Actually Did
The Study Population:
- Nurses' Health Study: 70,725 female nurses followed from 1986-2018
- Health Professionals Follow-Up Study: 40,742 male health professionals followed from 1986-2020
- All participants were free of major diseases at the start and answered questionnaires about their exercise habits every two years
Types of Exercise Tracked:
- Walking, jogging, running, bicycling, swimming
- Tennis/squash/racquetball
- Climbing stairs
- Rowing or calisthenics
- Weight training or resistance exercises
- Other activities specific to each study (yoga, yardwork, etc.)
What They Measured:
- Total deaths and specific causes (heart disease, cancer, respiratory disease)
- How much people exercised (measured in MET-hours per week—think of this as "exercise currency")
- How many different types of exercise people did regularly
Strengths: Why This Study Matters
Massive Scale and Duration
- Following over 111,000 people for three decades is like watching a small city grow old, giving researchers unparalleled statistical power to detect real patterns.
Repeated Measurements Over Time
- Unlike studies that just ask about exercise once, this one checked in every two years (up to 15 times per person), capturing how people's exercise habits actually evolved over their lifetimes.
Smart Design to Avoid "Sick People Exercise Less" Problem
- Researchers used a 4-year lag (didn't count exercise data until 4 years after it was reported) and stopped updating exercise info after people got sick, reducing the risk that declining health—rather than lack of exercise—explained the mortality patterns.
Validated Questionnaires
- The exercise questionnaires had been previously tested and shown to correlate well with actual activity levels (correlation coefficients of 0.54-0.69), meaning people's self-reports were reasonably accurate.
Comprehensive Adjustment for Confounders
- They accounted for essentially everything that might muddy the waters: smoking, diet quality, alcohol intake, body weight, family history, social connections, and more.
Novel Focus on Variety
- While others have studied total exercise amounts, this is one of the first large studies to specifically ask whether mixing up your exercise routine provides extra benefits beyond just the total time spent exercising.
Dose-Response Curves for Each Activity
- Rather than just "exercisers vs. non-exercisers," the study mapped out exactly how much benefit you get from different amounts of each activity type, revealing diminishing returns after certain thresholds.
Weaknesses: The Caveats to Consider
Self-Reported Exercise = Guesswork
- People estimated their own exercise time, and most of us are terrible at this (we either underestimate because we forgot that 20-minute walk, or overestimate because we counted the time we spent tying our shoes and chatting at the gym).
Intensity Mystery for Some Activities
- The study couldn't distinguish between someone leisurely paddling in the pool versus someone doing intense lap swimming, which matters enormously for health benefits—this likely explains why swimming didn't show the expected mortality reduction.
Mostly White Healthcare Workers
- 97% of participants were white nurses and doctors, so we can't be sure these findings apply to other racial/ethnic groups or people in different occupations with different physical demands.
The "Variety Score" Was Pretty Simple
- They just counted how many different activities you did regularly (1 point each), which doesn't account for whether you're combining complementary exercises (like aerobic + strength training) or similar ones (like jogging + running).
Some Activities Only Tracked for Part of the Study
- Weight training wasn't even asked about until 1990-2000, meaning they have much less data on this increasingly popular form of exercise.
Reverse Causation Still Possible
- Despite their precautions, people with undiagnosed chronic conditions might have unconsciously reduced exercise years before diagnosis, potentially inflating the benefits of higher activity levels.
Gender Differences Hidden
- Since one cohort was all women and one all men, they couldn't directly compare whether these patterns differed by gender within the same study (though their separate analyses suggested similar patterns).
Missing Data on Exercise Intensity
- The study used MET scores (metabolic equivalents) that assume standard intensity levels, but real-world intensity varies wildly—think power-walking versus window-shopping, both counted as "walking."
Key Findings Translated
The Sweet Spots for Different Activities:
- Walking: Benefits plateau around 7.5 MET-hours/week (roughly 2.5 hours of brisk walking)
- Tennis/Racquet Sports: Benefits max out around 5 MET-hours/week (about 1 hour weekly)
- Weight Training: Optimal around 7.5 MET-hours/week (roughly 2.5 hours weekly)
- Running: Benefits continue increasing even at high levels, particularly for heart and lung health
The Variety Effect:
- People in the highest variety group (regularly doing 3+ different activities) had 19% lower mortality than those in the lowest group (1-2 activities), even after accounting for total exercise time.
Swimming Surprise:
- Swimming showed no mortality benefit in this study, likely because the self-reported "swimming time" didn't capture intensity well—big difference between floating on a pool noodle and doing competitive laps.
Diminishing Returns:
- For most activities, the biggest bang for your buck comes from going from sedentary to moderately active; doubling your exercise from high to very high levels yields smaller additional benefits.
Bottom Line for Your Dinner Conversation
This study suggests the old wisdom "variety is the spice of life" applies to exercise too. While any exercise is better than none, people who mix walking with tennis, add some weight training, take the stairs, and vary their routine appear to live longer than those who just run every day—even if both groups burn the same total calories. The practical takeaway: instead of obsessing over running one more mile, consider whether you're neglecting strength training, or whether your routine has become too repetitive. Your body (and your lifespan) might benefit more from shaking things up than from doubling down on your favorite single activity.