Cardio Mark recently pointed me to this article that adds evidence to the existence of a weekly exercise ceiling above which, for some people, adding further training hours appears to carry negative benefits for long term health, and in particular for heart health. As you can see from the abstract, the authors find that doing no regular exercise is the very worst policy for long term health but that doing over 10 hours a week of exercise may bring a higher risk of mortality than doing around 2 to 5 hours.

Looking on a quarter-by-quarter basis, the majority of Crickles users average between 2.3 and 4.5 hours per week of exercise, which is right in the sweet spot according to the paper. Obviously this varies over time: if we look at the maximum hours of exercise averaged over a quarter, for the majority of the Crickles population this lies in the range of 5.5 to 10.8 hours. This means that quite a lot of us periodically creep above the exercise volume that the paper finds to be optimal. As the authors point out, genetics, diet and other lifestyle factors also need to be considered alongside raw exercise volume, not to mention the type and intensity of exercise. However, it does look as though it’s worth tracking the number of hours we exercise and giving some thought to whether persistently engaging in very high volumes of exercise, if we find ourselves doing that, may be counterproductive.

Crickles isn’t giving health advice but we are enabling you to quantify your exercise and the Seasonal page has had a major overhaul to enable you more easily to track your exercise volume over time. You’ll see that when you land on it it now looks something like this:

By default, it now shows average hours per week of exercise rather than totals, although this can be toggled back using the Show hours as dropdown in the sidebar.

There are now also hover tips – in the screenshot above, you can see that the user is averaging 2.4 hours per week of High intensity exercise in the current quarter (2022, Q1 at the time of writing). Here High reflects time in zones 4 and 5, Medium reflects time in zones 2 and 3 and Low shows time in zone 1. You can use the Heart rate zones dropdown to see more or less granularity: choosing Z1 to Z5 gives you the same detailed data that was previously given on the Seasonal page. Choosing Effort, Recovery on the Heart rate zones dropdown aggregates the data more, bundling all of time spent in zones 2 to 5 as Effort and breaking out time spent in zone 1 as Recovery for a simpler display:

To see your overall total exercise hours in the simplest way, select Totals only in Heart rate zones:

This shows that this athlete is averaging 8.4 hours per week of exercise in the current quarter.

Previously the Seasonal page only showed exercise time when heart rate was captured using a sports watch or chest strap. To enable you to see all of your recorded exercise time – although only moving time, not cafe time – activities are now included even when heart rate was not recorded. Generally, this time is shown as a grey Unknown heart rate zone, although for the Totals only display, which doesn’t give a zone breakdown, it’s just included in the total. If you’d prefer not to include activities that don’t have a heart rate record you can simply uncheck the Show hours when heart rate unknown? checkbox and they will be removed.

The Sport dropdown is of course still available, enabling you to see time spent in each zone by activity type. For example, you may regularly spend time on yoga for relaxation or do stretching sessions and record these on Strava. If so, you can easily see how much time you spend on these activities by selecting them in the Sports dropdown; then, if you wish, you can subtract that time from the overall total if you think that gives you a better picture of your true exercise volume. Note that time spent on sports such as outdoor cycling will typically involve a reasonable amount of time in zone 1 (a.k.a. low effort or recovery) – for example, when you freewheel down a long descent. Stripping this out of your average hours totals may be misleading as it’s an essential part of the sport and is likely to be included in the leisure-time sports activity figures used by the authors of the paper. It is, however, worth being aware of intensity composition and it is factored into the CSS-based analytics elsewhere in the Navigator.

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