The basis of a healthy body is a strong skeleton. Here's how to look after it.
It may come as a surprise to non-athletes, but even the superfit may have trouble with their bones. If you're a runner, for instance, your spine may be shrinking. Investigations recently completed at McMaster University in Hamilton, Ontario, suggest that individuals who run more than 40 miles per week have less sturdy backbones than sedentary people, and separate research carried out at the University of Maryland verifies that runners who train about 50 miles per week may have 10-per-cent thinner spines than average individuals. Both studies were carried out with male subjects, shattering the idea that amenorrhoeic female runners are the only ones with frail spines.
No one knows why running may prune the spine, although a reasonable guess has been that heavy- duty running can partially shut down one' s gonads, lowering the amount of sex hormone circulating in the blood. This would be bad for the bones, since both testosterone, the male sex hormone, and oestrogen, the female counterpart, are potent bone builders. However, participants in the McMaster study had completely normal testosterone levels, so something else must be going on. (The Maryland work didn't look at testosterone.)
Is it too much parathyroid hormone?
Recently, a second theory has popped up to replace the sex-hormone hypothesis. Some researchers are now suggesting that vertebral flimsiness might be caused by an over-production of 'parathyroid hormone', a chemical produced by small knots of tissue embedded in the thyroid gland; For example, a recent analysis of 14 female long-distance runners with low bone density revealed that they released excess quantities of parathyroid hormone and abnormally low quantities of another hormone called calcitonin after their workouts - and also following a calcium-containing meal. Since parathyroid hormone tends to make the bones thinner, and calcitonin stimulates bone building, such runners could easily develop more fragile spines.
It's not yet clear how widespread this parathyroid-hormone problem is, but it is clear that the loss in spinal density among runners is very troubling. Approximately one out of every 10 people in Britain and America already suffers from osteoporosis, one in three women over the age of 50 will experience a spinal fracture relating to osteoporosis, and one- third of all men over the age of 75 will suffer from spinal breakage. Those odds would probably worsen among runners who enter middle age with already damaged backbones, so what should runners - and other people - do to fortify their spinal columns?
Try other exercises?
Consuming enough dietary calcium is one partial solution, as is (for women) preserving menstrual function prior to menopause and undergoing oestrogen replacement therapy post-menopause. However, another good remedy is to find a form of exercise which specifically stimulates spinal bone-building. Since it' s clear that running is not the optimal exercise to enhance spinal bone density, what is?
Swimming and cycling are definitely not the answers, as a recent study with triathletes at St Mary's Hospital Medical School in London confirms. The St Mary's research reveals that triathletes have no better spinal (and total-body) bone densities than people who don't exercise, and in fact their skeletal thicknesses are sometimes LOWER than average. What' s eating triathletes' spines? Well, running can chip away at the spine, and cycling and swimming are both relatively non-weight-bearing activities, in which the body is supported by the bike or water, not by bones and muscles. Generally, weight- bearing activities put greater stress on the skeleton and lead to better bone building.
The issue of weight-bearing versus non-weight- bearing leads to the question of what bones actually 'need' in order to decide to add bulk. Strangely enough, scientists aren't exactly sure what encourages bones to thicken up, but it appears that bones respond either to large forces placed on them by muscle and tendons or to compression forces created during activity. An example of the former would be the large muscular forces placed on the dominant arm while serving a tennis ball (a tennis player tends to have thicker bones in the arm he/she uses for hitting the ball).
Squash and weight-lifting
That being true, it' s not surprising that scientists at the Tampere Research Station of Sports Medicine in Tampere, Finland, recently found that two sports - squash and weight-lifting - can have very positive effects on bone fabrication. 164 competitive female athletes from seven different sports actually took part in the new Finnish study, including 30 orienteers, 29 cyclists, .18 weightlifters, 28 cross-country skiers, 27 aerobic dancers, 18 squash players, and 14 speed skaters. Average age of the athletes was 24 years, and mean weight was 134 pounds.
As mentioned, the big winners in the bone-density race were the squash players and weight lifters. Compared to non-active control individuals, the bone- mineral densities of the squash players' spines were 14 per cent higher. In addition, their leg bones were 13-to-17 per cent thicker, and their foot bones were about 19 per cent more solid.
The weight lifters didn't fare badly, either. Their legs were 17 per cent thicker, their knee-caps were 18 per cent more solid, and their arms had 20 per cent more substance, compared to the non-exercisers. As in the St Mary' s study, cycling had little positive impact on bone-building: the cyclists' skeletal parts were no more solid than those of the sedentary control individuals.
Gymnastics as well
Why are squash and weight lifting so good for the bones? The sudden stops involved in squash place heavy forces on the leg bones, leading to their rapid increase in solidity. Likewise, weight lifting stresses both the legs and arms, providing a broader-based bone-building effect.
Gymnastics also seem to be great for bone-building - as long as female gymnasts can avoid amenorrhoea. Graduate research carried out by David Nichols at Texas Women's University recently revealed that eumenorrhoeic collegiate gymnasts had higher spinal bone densities compared to control individuals, and also deposited extra bone in their vertebrae during a 27-week gymnastics training programme.
There's also evidence that rowing may be good for bone-building. For example, the St Mary' s study mentioned earlier found that rowers had very high bone densities throughout their bodies compared to triathletes or sedentary control individuals. However, it's not clear whether the actual rowing - or the supplemental weight lifting carried out by the rowers at St Mary's - was the real reason for the upswing in bone.
It doesn't always work
So what should runners - and people in general - actually do to fortify their spines? Many athletes would probably have a hard time fitting squash into their schedules (the key problems, of course, are finding an open court and choosing the right tea to drink afterwards but that's all right, because Gail Dalsky, PhD, highly respected exercise-and-bone researcher at the University of Connecticut, says: 'Weight training is probably the best form of exercise for building bone density'..
Unfortunately, this link between weight lifting and dense spines is not automatic. For instance, scientists at San Diego State University recently put a group of active women through a vigorous three- day-per week 12 MONTH strength-training programme which included bench presses, lat pulls, shoulder presses, leg extensions, leg flexions, and also some back extensions and flexions to encourage spinal bone-building.
Muscle strength increased by up to 71 per cent, lean body mass expanded, and percent body fat declined, but there was no improvement in spinal density. The problem? As the researchers admitted, the spine wasn't adequately 'loaded' during the weight-training programme. Strains (forces) of fairly high magnitude are required to really wake up your ossified parts and make them hustle to create new bony tissue. Unfortunately, the back extensions and flexions utilised in the San Diego State study were carried out with Polaris weight machines. In other words, the subjects were seated as they exercised, their body weight supported by the machines. In addition, the forces placed on the back were only moderate, and use of the machines created little bone- stimulating compression of the vertebrae. It's likely that something other than weight-machine work is needed to really boost the spine.
Exercises to use
So what should you do? 'First of all, you need variety,' says Dr Wendy Kohrt, a noted bone researcher at the Washington University School of Medicine in St Louis. 'If you're doing the same form and amount of exercise all the time, your skeleton has probably already adapted to it and won't add on any additional bone.'
'You need to try to put a fair amount of force, and some compression, on your bones,' says David Nichols, main investigator in the gymnastics study noted earlier. To make it easy for readers of this special issue of PEAK PERFORMANCE to fortify their spines, three bone-building exercises which put both compression and force on the spin (the drop jump, rowing with tubing, and the push press) are described below. Remember, if you have a history of back problems, consult your doctor before attempting any back- building exercises.
1. The first spine-enhancing exercise, the drop jump, couldn't be easier to complete. Simply drop from a bench or high step, landing with knees bent, and then explode upward into the air. The impact of landing and the subsequent upward acceleration both place compression and force on your spine.
2. To carry out the second exercise, you must first create your own home rowing machine (it will only cost a few quid). Simply buy some resistant tubing from an athletic supply company, the kind with a handle on each end of the tube. Anchor the middle of the tube around a support structure and grab the handles, making sure that you are sitting down on a small bench (about four inches high) facing the support structure, with your legs slightly flexed at the knees. Lean back so that your upper body makes about a 45-degree angle with the vertical (this works your lower back muscles), pull the handles to your waist, and then pull the handles of the tube up towards your shoulder. You'll strengthen your arms, shoulders and back, and put some nice compression on your backbone. Over time, you should try to use stiffer and stiffer tubing.
3. The third exercise, the push press, is a lot of fun to carry out. Stand erect and rest a barbell (with a comfortable amount of weight) on the fronts of your shoulders, with your palms facing upwards. Then, simply flex your legs at the knees, and finally push the weight overhead as you rise to a straight- up standing position. The overhead weight, the semi-crouch position you take before lifting the bar-
bell, and the final acceleration upward all put compression and force on the spine. Start with two sets of eight reps, gradually building to three sets of 10 reps, and use heavier weights over time.
Final thoughts
Here are some summary points which should help you boost your backbone:
1 Carry out your strength training regularly and systematically over long periods of time, bearing in mind that the benefits of strength training on your spine are not immediate. Some studies suggest that - using a three-times per week strength training programme - it may take nine months or more before your spine really begins to be refurbished.
2 To build spinal bone density optimally, it makes little sense to use variable-resistance weight machines, even ones which are supposedly designed to strengthen your back. Studies suggest that these machines actually do little to strengthen the muscles which run between your vertebrae. Thus, you wouldn't expect them to be able to create large enough forces to tack bone on to your back. It' s better to use free weights.
3 If possible, try to use the heaviest weights which you can manage safely. Bones seem to be more responsive when a small to moderate number of large forces are placed upon them, rather than lots of small forces.
4 Make sure that you're consuming enough calcium each day. Fortunately, that part of the equation is fairly easy. To reach your recommended daily allowance of calcium, you need only ingest three cups of either milk or yoghurt daily (after menopause, women should shoot for four to five cups, as should men over the age of 60).
Owen Anderson