Bone loss science

One of the reasons I enjoy poring over certain types of sports training books is the reems of odd scientific studies they usually discuss. 

I'm reading "Bike for Life: How to Ride to 100" by Roy Wallack and Bill Katovsky.  At first, it had lots of funny stories of their crazy ultra-cycling escapades with high elevation climbs from hell.  But then an offhand comment sent me ahead to Chapter 9 on the discovery of widespread prevalence of developing osteoporosis in male elite cyclists, even young ones.  Female too, it turns out.

The chapter gives an interesting tour through the vagaries of scientific method, such as doing a ton of studies on impact and resistance and diet but not considering calcium loss in sweat content. 

But Bill "Bagman" Gookin, a marathoning biochemist who puked up green Gatorade during a failed Olympic trial, back in the day taped plastic sandwich bags to his back, chest, and armpits while running to gather sweat samples.  He found calcium as well as potassium, sodium, magnesium, and all the usual things sports drinks are concocted to replace.  Yet most drinks do not include calcium, or did not.  I looked, the increasingly popular Nuun fizzy tablets do, though not in the All Day version.

So then they do the maths: 200 mg calcium lost in 1 hour x a seven-hour century ride = 1,400 mg.  12 hours a week amounts to 2,440 mg lost.  Two day's RDA a week, year after year...

Triathletes, however, have strongass bones because the impact of running,  and resistance training for those who also lift weights.  Turns out cycling is like a mild version of spaceflight- weightlessness causes bone loss from no impact or resistance, causing weird workout machines (or plain old resistance bands) to be concocted and used up there.  Another argument for cross training besides over-development of specific muscles.

Then there's the resting when not riding, so less walking, running, jumping sports, and weight lifting.  Why studies and education make a difference in training: what you don't know could drastically thin your bones.  I read a lot of cycling books and magazines in the eighties, but they did not know this yet...

Plus, phosphate from soft drinks leaches calcium too.  They harp on the sugar and obesity, but, man, even diet drinks have the phosphorus that sucks out calcium... Easy to forget, like all the individual little pieces.  What I love about these types of discussions in training books is the sheer number of interacting and sometimes contradictory factors at play.  (X is good, but detracts from Y, which you also need.  And Z is just bad, but who wants to give it up?) 

In the end, we do need science, not just doing what feels right, or trial and error...  Except...