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Oestrogen and muscles
Actual research into oestrogen's effects on muscles and exertion first came to the forefront in the 1970s, when investigators at various universities began to discover that when oestrogen was added to animal feed, the animals grew larger and had greater muscle mass. This came as a bit of a shock, since it was believed that oestrogen fattened - rather than beefed up - living organisms, but the observation was repeated in literally hundreds of different studies.

Basically, researchers were able to show that the addition of oestrogen to the diets of cattle or sheep could hike weight gain by about 15 per cent and boost 'feed efficiency' (the degree to which ingested food is actually transformed into new tissue) by around 12 per cent. As mentioned, these weight gains were produced in animals which ended up with relatively more muscle and less fat, compared to cattle or sheep who grazed without oestrogen additives.

What was notable about these studies was that oestrogen seemed to produce a decline in blood levels of amino acids and in blood and urinary concentrations of nitrogen, effects which basically meant that oestrogen was either stimulating muscles to synthesise protein at greater rates or else protecting the proteins which they already contained more effectively. Oestrogen-fed animals also did a better job of holding on to calcium and phosphorus, two minerals which are critical for muscle function. Overall, experts claimed that adding oestrogens to cattle feed would provide the United States with 135 million (!) extra kilograms of animal protein per year, without any increase in what the animals actually ate! It was as though oestrogen was behaving just like its male counterpart, testosterone (of course, most people aren't aware that oestrogen is formed from androgens in the ovaries and so is not very chemically dissimilar from its hormonal brother).

And a critical piece of information was that increased oestrogen boosted blood levels of 'growth hormone', an extremely important chemical released by the pituitary which stimulates tissue growth, enhances fat degradation, and protects muscle cells from breakdown. In fact, scientists discovered that one could either inject animals with growth hormone or simply place oestrogen in their feed; the end results were fairly similar.

And as you might guess, the tissue-building effects of oestrogen were usually observed in female cattle, but not in males. In fact, when bulls were given oestrogen they began to get fat and grow breasts, instead of bulking up (that's one of many reasons why American beef herds aren't all charged up on oestrogen right now). However, young, sexually immature bulls did grow like wildfire when given oestrogen supplements.


Muscle protection
That's all very interesting, but the key effect of oestrogen is probably not to enhance muscle growth but rather to protect muscles from damage during strenuous exertions and thereby boost recovery rates during rigorous training. Studies have shown that females regain muscle strength more quickly than males following very hard, muscle-damaging workouts.

How can oestrogen preserve muscle function? Well, since about 1986 scientists have known that oestrogen has unique 'antioxidant potential', which basically means that it can shield cell membranes (including muscle membranes) from 'peroxidation reactions'. Peroxidation is serious; it can destroy membranes and ultimately lead to the destruction of muscle cells themselves. Since tissue-damaging peroxidation reactions are stimulated by endurance exercise, it's easy to see a mechanism by which oestrogen could promote muscle preservation and recovery during tough training. Oestrogen's exact modus operandi in protecting membranes isn't known, although it has been established that muscle membranes do contain receptors for oestrogen.

In fact, some studies have suggested that oestrogen and its related compounds are more potent antioxidants than the highly touted vitamin E. In addition to giving cell membranes a boost, oestrogen is also thought to protect against the peroxidation of LDL-cholesterol (aka bad cholesterol), an effect which may at least partially explain the lower incidence of heart disease in females, compared to males. Studies have shown that therapeutic doses of oestrogen significantly reduce the incidence of and mortality from cardiovascular disease, as well as chest pain and blood-vessel blockages in postmenopausal women.


Oestrogen in the athletic arena
What about oestrogen and athletic activity? When male and female rowers recently embarked on an extremely challenging 30-day training period, males exhibited significant signs of membrane peroxidation (determined by examining blood levels of chemicals produced by peroxidative processes), while females did not. In addition, when male rats become vitamin-E deficient, they respond to training very poorly and suffer from reduced exercise capacities, while female rats low on E tend to get along just fine, as long as oestrogen levels are okay. Similarly, high-intensity exercise depletes muscle vitamin-E levels in sexually immature animals but not in sexually mature females with normal oestrogen levels, another indication that oestrogen operates in muscles as an antioxidant and protects them from damage during strenuous training.

And it's tempting to think that the female advantage in ultra- competitions may operate in this way: during the race, muscle membranes become progressively more damaged, but to a lesser extent in females, compared to males. In addition, mitochondrial membranes and a membranous network inside muscle cells called the sarcoplasmic reticulum begin to break down. As healthy calcium ebbs and flows between the reticulum and the contractile proteins inside muscle cells, the cells alternately relax and contract. If the reticulum becomes torn and leaky, muscle power decreases. Could oestrogen-induced preservation of muscle membranes be a reason why exercise intensity during muscle-damaging ultras plummets from 60% VO2max in women to just 50% in men?. We've put that thought in the form of a question, since the phenomenon hasn't actually been tested yet.

Does oestrogen also have any direct effect on muscle force per se? Well, yes. For example, females generally experience a fairly precipitous loss in muscle strength after they have gone through menopause. This decline is not necessarily the result of muscle atrophy (the actual loss of muscle tissue), because it is also apparent if muscle force production is expressed per unit of muscle cross-sectional area. However, studies carried out at University College in London reveal that this drop-off in force can be prevented when post-menopausal women are given oestrogen therapy, indicating that oestrogen may have a fairly direct effect on force production in muscles. As an aside, males don't experience a 'testopause' which is quite as dramatic as the female menopause. As a result, they aren't hit with a similar decline in muscle strength per unit area until they reach the age of 60 or so.


Preventing long-distance slowdowns
Will male bodybuilders soon begin to worry about being too oestrogen-poor and begin injecting themselves with oestrogen in order to bulk up and enhance their ability to recover from harsh training? Since they're wimps when it comes to injections, will long-distance runners soon be sprinkling oestrogen on their breakfast cereal in hopes of improving their marathon or ultra-marathon times? Well, amazingly enough, scientific studies have shown that - at least in rats - males treated with oestrogen before embarking on two-hour runs do experience less muscle damage. This overall 'oestrogen-stacking' scenario is not too likely, however, bearing in mind the swagger of machismo - and the fact that the experimental bulls got fat instead of muscular after taking oestrogen. But we shouldn't be at all surprised to see the girls winning and placing high in ultra-race competitions and outdistancing those male runners who can beat them rather handily in 10Ks. As the South African research has shown, females can dominate males in such longer races, even though the males have greater aerobic capacities and faster 10-K times.

We don't know whether this is because oestrogen pushes muscle metabolism toward fat oxidation during exercise, an effect which conserves glycogen, or if it happens because oestrogen preserves strength and protects muscles so well during high-mileage training and actual marathon and ultra-marathon racing. The bottom line is that females certainly tend to outwork males in such events, moving energetically along at 73% of VO2max in marathons, versus 66 to 70% for males, and at about 60% of their VO2max in ultramarathons, while males crawl toward the finish line at just 50%. of maximum.

If you're a male - or female - who tends to slow down too much when you run the marathon, what can you do to prevent it? Focusing more heavily on long runs in training is not the answer; in fact, it's one of the key causes of marathon slowdowns. For example, most people who run the 10K in 40 minutes prepare for marathons by doing a lot of running at about eight-minute per mile pace. That's a big mistake!
You see, if you can run a 10K in 40 minutes, you should be able to run a marathon in about 3:07 (we get the 3:07 by multiplying 40 by 4.667, the 10K-to-marathon conversion factor). That's a pace of 7:08 per mile. Going out and running lots of 15- to 20-milers at about eight minutes per mile, the usual gambit, is going to enhance your ability to run your marathon at eight-minute pace, not at 7:08 tempo. Those long runs are fine for general strength, aerobic development, and calorie burning, but your marathoning will get a greater shot in the arm if you focus instead on gradually increasing the distance you can run at your goal speed, which in this case is 7:08 velocity. Simply start with two to three continuous miles and gradually progress until you can cover 12 or 13 miles at your goal pace in one big swallow.

Of course, overall fitness is also more critical than an ability to handle very long runs at slow paces. Intervals at 5-K speed, long intervals at 10-K pace, tempo runs at just off 10-K pace, and hill sessions are going to do far more for your marathoning than just ambling along lethargically at well-off marathon pace. With more specific, higher-quality training and a proper taper, you can cruise through your marathon in your best-possible time, not in a too-well-practised shuffle.

Owen Anderson

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