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.

Low Iron Still an Issue in Professional Athletes

Despite the fact that most of you are probably weekend-warriors or recreational athletes, I suspect that some of you expose their bodies to similar stressors as professional athletes do. Therefore, I assume you'd be interested in a recent study coming from German scientists (Reinke. 2011) who found that "although recuperation seems to allow a certain recovery of iron storage, particularly in athletes with initially low ferritin levels, this retrieval was insufficient to fully normalise reduced iron levels."

The scientists had previously examined the iron metabolism in 20 elite rowing athletes and 10 professional soccer players at the end of a competitive season, after recuperation and during pre-season training and found:

At the end of season, 27% of all athletes had absolute ID [iron deficiency] and 70% showed functional ID. Absolute iron depletion was not generally restored after recuperation and observed at all time points in 14% of the athletes. Although athletes with initially low ferritin levels showed a slight increase during recuperation (p < 0.09), these increases remained within borderline levels. Furthermore, 10% showed borderline haemoglobin levels, suggestive of mild anaemia, as defined by the World Health Organisation.

While I would not suggest supplementing with iron without due reason, this study should remind you to have your levels checked, at least once a year in order to intervene before you actually feel the negative effects of low iron and anemia.

Loss of Trace Elements not a Concern in Well-Hydrated Athletes

If you are a hard-training athlete you need more than "trace amounts" of trace elements, don't you? No, actually not. You may be somewhat disappointed now, but the expensive trace element supplement you just ordered might turn out to be a complete waste of money - at least, this is what the results of a recently published study by Carlos González-Haro et al. (González-Haro. 2010) suggest.

Figure 1: Changes in plasma trace element levels (Zn, Mn, Se and Co) for the different relative exercise intensities studied and the 7 min recovery period.

As figure 1 (above) shows, lactate concentrations constantly increased in the course of the 7 minutes after a cycloergometer test, where, after a warm-up of 10 min at 2.0 W kg⁻¹, workload had been increased by 0.5 W kg⁻¹ every 10 min until exhaustion. The trace mineral concentration, on the other hand, remained stable over the whole study period (exercise + recovery). This observation led the scientists to conclude ...

[...] in euhydrated well-trained endurance athletes no effects on plasma levels of Zn, Se, Mn and Co were observed either during medium duration exercise, at a full range of intensities (41–92%VO_2peak), or during a seven-minute recovery period. These subjects showed no deficiency in Zn or Se and probably were not deficient in Mn or Co either (though cutoff levels are not known).

So, if you have not opened your "high quality trace element" supplement yet, make use of your 14-days conversion right ;-)