The Thirty Year Follow-up, 1996

Three decades after the first study was organized the authors of the original study contacted all the participants from the summer of 1966. Everyone agreed to meet at a reunion lunch and discuss a proposal for a follow-up study that would consist of training only, no bed rest and no needles. Here's a collection of some of the pictures my wife and I took.

The first photo, from left to right: Dr. Darren McGuire (lead author), Gregg Hill, Leo Luebbenhusen, James Hulsey, Dr. Jere Mitchell.

The next photo shows, Dr. Robert Johnson, Kaz Laszlo, Dr. Peter Snell (former mile world record holder at the time of the 1966 study).

The final photo photo shows Bill Bowman with wife and son.

Below, from left to right, Drs. Bengt Saltin, Gunnar Blomqvist and Ben Levine.

We had all been tested during the spring to look for any sign of heart disease. Everybody turned out healthy. During the summer we were run on the treadmill at the Institute for Exercise and Environmental Medicine (Presbyterian Hospital, Dallas). Since I had spent several summers working as a technician at Southwestern Medical School in the 60s, I was able to compare the equipment of 1966 with that of 1996. Everything was now computerized. Where my boss in 1966 was struggling to learn FORTRAN to program a mainframe with punch cards, everyone now had a PC at their desk and there were several PCs connected to the monitoring equipment I was wearing. The mouthpiece into which I exhaled had sensors that measured the volume of my exhaled air and its oxygen and carbon dioxide concentrations. It was now possible to measure my oxygen uptake breath by breath. Final results were available within the hour. In 1966 when I did the calculations as a technician I had a large desk calculator and a notebook. The calculations couldn't be completed until the next day because the chemistry lab had to do the careful quantitative analysis required with equipment that had been developed in the 1930s.

Weighing someone under water and comparing that with their dry weight, and then determining the volume of air in the lungs, can be used to determine the percentage of body fat. When this picture was taken I had poison oak rashes from working in the back yard. The chlorine in the water made them sting.

Here is a sub maximal treadmill run. The heart rate monitor shown at the bottom reads 106. Expired gasses can be measured to determine oxygen uptake, and with the bag on the right, which contains a trace of acetylene, the cardiac output while running can be determined.

Here I'm resting after the sub maximal run, still hooked up to the EKG leads and blood pressure cuff. That's a Polar heart rate monitor on my wrist.

Above is the maximal treadmill run. The treadmill grade is increased every one or two minutes until I indicate I want to stop. Here Dr. McGuire is collecting a bag of expired air for later analysis. While running the subject is switched to the black bag hanging from the mouthpiece. It is first filled with an air-acetylene mixture. The amount of blood flowing through the lungs will be reflected in the concentration of acetylene in the expired air. In the 1966 runs, arterial and venous catheters were used.

When we were first examined it was obvious that we were all heavier than in 1966, and it was mostly fat. There had been little change in fat-free body mass. An interesting development was that our hearts had all gotten larger. This was not a result of heart disease. Since our cardiac outputs had not dropped, but our maximum heart rates had, to keep cardiac output at the same level, our hearts had learned to pump more blood with each contraction. I had kept running after 1966, with periods of rather intense training from 1973 to 1977, and from 1980 to 1984, and in the years before the 1996 study I had been jogging with my wife.

After the first screening test on the treadmill I knew that I could do much better if I started training again. I was too excited to sleep well that night in the motel, so I fell asleep in the noisy MRI scanner the next morning when they were measuring my heart volume. Once the doctors told me to start running I began training 5 days each week with my dalmatian Marlowe.

The factor that seemed most important in our reduced exercise capacity was the reduced ability of our muscles to extract oxygen from the blood passing through them. Our cardiac outputs were the same as in 1966 after training. Some of us showed a reduced maximum heart rate, so the heart compensated by enlarging and pumping more blood with each stroke. It may be that heart rates are reduced because nervous and hormonal stimulation are less effective in older men. Since the heart has its own internal source of stimulation, which is intrinsically slower than what is normal in a younger man, the heart's own mechanism may control its rate as we age. The decline in maximum heart rate occurred in the two trained individuals, perhaps because their hearts were the largest and could best make the change to the new control regime.

The individual adaptations to training were interesting. Everyone showed an increase in the amount of oxygen that could be extracted in the muscles except for me, who ran regularly more years than not during the intervening thirty years. My extraction rate was almost as large as in 1966 (14.7 vol% in 1996, 16.6 vol% in 1966), and this rate might be increased by more intensive interval training. Running employs large muscle groups for balance and propulsion, more than any other exercise except cross-country skiing. Cycling and swimming don't require that one support one's body weight, so maximum oxygen uptakes for these athletes are less than for skiers and runners.

If my maximum oxygen uptake is as large as it was when I was 19, why can't I run a mile in less than 5 minutes, as I did at 19 and at 29? The follow-up study doesn't address performance, so my answer is an informed guess.

In his book Prime Movers. A Natural History of Muscle (pages 121-125), Steven Vogel explains how tendons are excellent energy stores. When muscles contract and stretch the tendons attached to them, considerable energy can be stored. Vogel sites studies that show for large mammals, such as us, about half the energy of locomotion is stored in stretched tendons. The Achilles tendon and the tendons of the foot store much of the energy used to propel us forward. My guess is that in older people the tendons are less efficient and so store less energy than the tendons of younger people. Less stored energy means less released energy on push-off, so the running stride is shorter, and the runner is slower. The best example of this unavoidable deterioration is the recent career of Johnny Grey, the American record holder in the 800 meter run. In his early 20's he ran 1:42.60, still an outstanding time. In 2000, as a 40-year old, he could not get under 1:48 in spite of hard training. His long and successful career was ended by ageing, a process no amount of training can retard.

Cycling and swimming do not have the significant eccentric muscle component that running has, so it might be possible for these athletes to maintain the same performance level if they maintain their training. The training volumes of professional cyclists and swimmers are often very high. As they age, the capacity to regenerate muscle tissue after high volumes of training will diminish, and injuries that would have healed at age 21 do not heal quickly at age 32. This has certainly been my experience in my fifties compared to what I remember from the first thirty years of my life. At any rate, the ability to maintain a high maximal oxygen consumption after peak athletic years is very useful, even if the performance isn't there.

Recommendations

Exercise training is the best preventative for obesity and type II diabetes, and it also seems to be the best way to treat these conditions when they are first detected. Since the benefits of exercise are great it is surprising that it seems to be a distant second to dieting as a means of improving one's health. For children the recommendation for more exercise seems to be nothing more than slow walks around their school's running track. Older adults may find beginning an exercise program difficult, but children will certainly find it easier, especially if they are a part of a program that is fun. School sports serve competitive, not fitness goals. Local athletic clubs are a better solution. Running, cycling, swimming, throwing and jumping events, for individuals and teams would be a good way to start children on a lifetime fitness program. It must be understood that a good level of physical is the best preparation for popular team sports. University physical education programs should include graduate programs for the training of coaches with a good foundation in physiology and kinesiology. These coaches could provide training guidance for local clubs. Professional sports teams all have strength and fitness coaches, and so should local athletic clubs. Many children, especially girls, start participation in sports with a poor fitness level and too often get injured, requiring surgical repair to be followed with a rehabilitation program that is not pursued aggressively. A children who learn how to be fit will have something that will be useful throughout their lives.

The results of the follow-up show that there is a fountain of youth, it's just that you have to work hard to drink from it. It's very much a case of you get what you pay for.

© 2005 by Gregg R. Hill