At age 86, I can look back at more than 75 years of daily exercising and can tell you that there is a huge difference between the way that your body responds to exercise when you are young and when you are old. The key to healthy exercising for younger people is to try to put some intensity into some of their workouts. Older people should try to exercise every day and try to use some intensity when their muscles feel fresh, but when their bodies talk to them with discomfort, they should exercise at reduced intensity or take the day off. If you fail to listen to your body, you will soon learn that pain and discomfort are signs of an impending injury. See Recovery: the Key to Improvement in Your Sport

Exercising Intensely Makes You a Better Athlete
At the 1952 summer Olympics in Helsinki, Luxembourg’s unheralded Josy Barthel won the men’s 1500 meter race in 3:45.2, equal to a 4:03 mile. He had gone from a virtual unknown runner to Olympic gold by doing all his interval training at sub 4-minute-mile pace. In that same race, England’s Roger Bannister set a British record in the 1500 meters, but finished in fourth place. As a medical student, Bannister had little time to train, so after the Olympics, he took shorter workouts, but tried to do his intervals at sub 4-minute-mile pace. Two years later on May 6, 1954, he ran the first sub 4-minute mile in 3:59.4. In the 67 years since then, more than 1500 runners have run faster than four minutes for the mile (Track and Field News, April 15, 2021).

I trained for marathons by running an interval workout of 20 quarter-mile repeats at 75 seconds each. That’s a pace of 5-minute miles, which is way too slow, and I was a very mediocre marathon runner. In 1954, Josey Barthel came to Harvard and trained regularly on the Harvard track. At that time, the best marathon runners in America were training at a very slow pace. Some didn’t do intervals at all, while many others were running their intervals at 5-minute mile pace. A relatively mediocre marathon runner at that time named Nick Costes decided to train for the marathon by doing sub-4-minute-mile intervals with Josey Barthel who was training for the mile. He was the first American marathon runner to train by doing intervals that fast. In 1955, after just one year of training that fast, he was the first American to break 2:20, when he finished third in the Boston Marathon in 2:19:57. In the 1956 Boston Marathon, he improved his time to 2:18:01, also won the National Marathon title in Yonkers, and was the top American finisher in the Melbourne Olympics that year. Today virtually all top distance runners are running their quarter-mile repeats in under 60 seconds. That’s 4-minute mile pace. Their workouts are often so intense that they have to take two or three days of slower running just to recover. Since “hard day” workouts were less intense in the early 1950s, top runners used to need only 48 hours of easy slow running to recover for their next fast workout.

Why You Lose Muscle Strength and Size with Aging
Muscles are made up of hundreds of thousands of individual fibers, just as a rope is made up of many strands. Each muscle fiber is innervated by a single motor nerve. With aging, you lose motor nerves, and with each loss of a nerve, you also lose the corresponding muscle fiber that it innervates. For example, the vastus medialis muscle in the front of your thigh contains about 800,000 muscle fibers when you are 20, but by age 60, it probably has only about 250,000 fibers. However, after a muscle fiber loses its primary nerve, other nerves covering other fibers can move over to stimulate that fiber in addition to stimulating their own primary muscle fibers. In one study, lifelong competitive athletes over 50 who trained four to five times per week did not lose as many of the nerves that innervate muscles and therefore retained more muscle size and strength with aging than their non-athlete peers (The Physician and Sportsmedicine, October 2011;39(3):172-8).

Aging Increases Risk for Injuries
When middle-aged and older people start an exercise program, they are at increased risk for injuries, usually because they try to train like younger people do. The muscles of older people contain fewer muscle fibers and therefore are much weaker than those of younger people. Older people should not try to put as much force on their muscles as younger people do. That means that they should lift lighter weights and run slower because the faster you run, the greater the force on your muscles and the more likely you are to tear them.

If your favorite sport becomes painful for you, it is probably time to switch to another sport or exercise activity. I switched from running to bicycling at age 55 because pedaling is done in a smooth rotary motion instead of pounding on the pavement. Swimming or jogging in water are also usually safe as the buoyancy of the water dampens impact and helps to prevent joint damage. People with cartilage damage in their knees or hips and those with hip or knee joint replacements should never run, jump, or walk fast, because the impact of your foot hitting the ground causes further damage. Your bones also become thinner and weaker with aging, which increases your chances of breaking them. One in three people over 65 suffers major falls, and the United States has the highest rate of hip fractures in the world (Archives of Internal Medicine, September 26, 2011). Diana has such severe osteoporisis that she rides only on a trike, and our tandem group rides are now done on a tandem trike. A stationary bike or a swimming pool are other good options for avoiding falls or impact injuries.

Lessons from the Ancient Marathoner
If you want to gain maximum training effects and top health benefits from your exercise program, set up your schedule so you exercise more intensely on one day, feel sore on the next day, and then go slowly for as many days as it takes for your muscles to feel fresh again to take your next fast workout. However, be aware that as you age, your muscles become weaker and take longer to recover from each workout so you are at increased risk for injuring yourself and will also take longer to recover from an injury. Always end your workout immediately if you feel pain in one area that does not go away when you slow down or stop.