Exhaustive Aerobic Exercise Increases Serum Calcium Levels and Dietary Requirements

You probably have heard of the fundamental importance of calcium as a structural component of bones. Yet, calcium is way more than the building block of our bone structure and the concrete the of the hopefully non-existent plaque in your arteries. It is also one of the major players in muscle contraction. Thus, it is not very surprising that a group of Iranian Scientists (Pourvaghar. 2011) found major effects of pro-longed (15min) high intensity aerobic exercise on serum calcium levels of 12 randomly selected student athletes (22.36y; 75kg @ 1.76m):

[…] the participants' mean of serum calcium concentration in the first stage and before Balke exhausting aerobic exercise was measured 98.38 ng/mic L. In the second stage, i.e. after the exhausting aerobic activity, it increased to 114.96 ng/mic L. Research results indicated that the difference in serum calcium concentration between the first and second stages is significant (P= 0.0001).

With the calcium that is appearing in the blood of the athletes being leeched from bones, organs to fulfill the increased calcium needs of active muscle tissue. Due to calcium “consumption” and urinary losses, the scientists speculate, the overall result to be a negative calcium balance.

Figure 1: Serum Calcium levels of athletes before, immediately after and 24h after exhaustive aerobic exercise. (Pourvaghar. 2011)

In view of the fact that, in the 24h after exercise, there is no sudden falloff (only -9.13%) of blood calcium, I would yet advice against extensive calcium supplementation. Previous works from other researchers have conclusively shown that a nutritionally dense, calorically adequate, diverse, calcium-rich diet satisfies the needs of both, the average gymrat and the hard training endurance athletes.

For athletes on a weight-reduction diet, or active gym-goers who – due to whatever other reasons – consume a diet that is low (<1.000mg/d) in calcium supplementing with a bio-available form of calcium, like calcium citrate, could yet be a viable strategy to prevent bone loss and sustain exercise performance.