They are hard, but we do have some. And even the most naive physical activity level vs all-cause-mortality studies show a mild effect at best. No controls. Com

They are hard, but we do have some. And even the most naive physical activity level vs all-cause-mortality studies show a mild effect at best. No controls. Common sense would tell you that physical activity has to spuriously correlate with healthiness. Many conditions will simply render you unable (or less able) to exercise. So what are the odds a properly designed longitudinal study would actually yield a bigger life expectancy increase? Seems very unlikely to me. The ones that we do have set an upper bound as far as I'm concerned. Almost certainly has to be lower. I understand that you're talking about a specific kind of exercise and most of what's out there doesn't speak to that. But nonetheless I'd be very skeptical given how little effect has been shown for general physical activity. And we do have plenty of similar studies showing random benefits of various exercises in a clinical setting.