I think the benefits of exercise are fairly well established, so I don't want to call that into question. But given the extremely small amounts of exercise described here, I do wonder if these particular results are driven by reverse causation, with people who are healthier being more able to engage in moderate to intense exercise for a minute or two on occasion.

For example, I'm in my early 40s, and I always run up stairs. I don't climb long flights of stairs often enough for this to be a significant contributor to my overall level of fitness, but it is a marker of fitness. If I had a BMI of 35, I probably wouldn't be able to do this.

Obviously doing this much exercise on its own is still better than nothing, but I think we should be skeptical of claims that such large benefits can be realized from such small amounts of exercise, at least when based on evidence of this quality.