Why One Run Isn't Enough: 30 Years of BMJ Data on Variety and Longevity

A large BMJ Medicine study of 111,000 people over 30+ years showed that exercise variety reduces the risk of death independently of the total volume. A bonus is that the benefits aren't endless. There's a saturation point.

What have [they/you] done

Data from two large Harvard cohorts were combined: the Nurses’ Health Study (nurses, from 1986) and the Health Professionals Follow-Up Study (male health professionals, from 1986). A total of 111,467 participants. At the start, all were healthy: free of diabetes, cardiovascular, oncological, respiratory, and neurological diseases.

Every two years, a survey on physical activity: walking, running, swimming, cycling, tennis/squash, rowing, and calisthenics, strength training, yoga/stretching, gardening, climbing stairs. Over 30 years, 38,847 deaths were recorded.

Activity was counted in MET-hours per week. MET is the factor by which an activity is more energy-consuming than resting. Brisk walking is about 3.5 METs, running at 8 km/h is about 8 METs.

Different species - different effects

The most active participants in each category were compared with the least active. If a person walks a lot on a regular basis over many years, their risk of death is 17% lower than that of people who hardly walk at all. The other categories yielded the following figures:

  • Tennis, squash, rackets: −15%
  • Rowing or calisthenics: −14%
  • Strength training: −13%
  • Running: −13%
  • Jogging: −11%
  • Climbing the stairs: −10%
  • Bicycle: −4%

Swimming, surprisingly, did not demonstrate a significant reduction in risk in the primary analysis.

It is important to understand what these percentages mean. It is not a case of “started running – minus 13%”. This is a comparison of extremes – many years of regular exercise versus almost no exercise at all.

Main discovery: diversity

Separate layer of analysis: participants were divided by how many different types of activity they engaged in. Not “how many in total”, but “how many types”. The most varied group versus the least varied — after adjusting for overall training volume — had a 19% lower risk of death from all causes. And a 13% to 41% lower risk of death from cardiovascular, cancer and respiratory causes.

The key is “after adjusting for volume”. This means diversity provides a benefit on its own, additionally. Not “whoever does more different things automatically does more, and therefore dies less.” But rather “at the same training volume, whoever combines several types dies less often than someone who does only one type.”.

Saturation point is around 20 MET-hours

The relationship is not linear. The benefit from total training volume plateaus at around 20 MET-hours per week. This is approximately:

  • 5-6 hours of brisk walking per week
  • Or 2.5 hours of running
  • Or a combination of several types

For context: the WHO recommends a minimum of 150 minutes of moderate activity per week - that's around 12 MET-hours. This means that even doubling the WHO's recommendation is already in the plateau zone. Running for 4 hours every day no longer brings additional benefits for mortality.

What this research does not prove

This is an observational study. It shows associations, not causation. Limitations to bear in mind:

Activity is self-reported, not an objective measure. People systematically overestimate or underestimate their activity. MET estimates were calculated assuming full engagement in an activity; in practice, intensity varies. Almost all participants were white, limiting the applicability of the findings.

The most significant limitation is that more active participants were generally healthier: they smoked less, had lower blood pressure, ate better, and had a wider social circle. It is difficult to separate the “effect of diversity itself” from the “effect of a generally healthy lifestyle”, even with the best statistical adjustments.

Honest wording of the finding: People with a wider range of activities have a lower mortality rate, and this association remains after adjusting for volume. No more and no less.

Which of these is useful?

Three things remain independent of restrictions:

Walking is the most democratic tool. The highest indicator among individual types of activity. No need to run – walk, and add something on top.

If there are 4-5 hours a week, it's better to spread them across different activities. Strength training plus walking plus something playful (tennis, badminton, swimming, basketball with friends) works better than the same 4-5 hours of just strength training or just running.

Saturation point – around 20 MET-hours. This is achievable for anyone who doesn't train professionally. Trying to do twice as much doesn't bring proportionally greater benefits for life expectancy.

The principle of diversity is one of the foundations of how I I am building the life:)on platform for active peopleA variety of workouts, progress tracking, locations, and events all in one place – not ten separate apps.

Sources

Vitalii Founder of life:)on

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