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1st Mar

2018

Do Your Exercises Improve or Worsen Your Health?

This heading no doubt appears controversial, at first glance. By health, I here mean primarily musculoskeletal health and fitness, but not only that, as I will explain.

I can recall a mentor early in my career stating that “exercise can be good, but it can also be bad.” He was referring to rehabilitation exercise, and that statement is in particular true for such exercise, where each type and stage of injury, and healing, demands a different choice and dosage of exercise.

This also applies to conditioning exercise and sports,, which is what this letter is about. I will not discuss the many health promoting effects of cardiovascular training, in this letter.

This subject could be discussed in detail in a lengthy essay, however I will try to be brief and to the point. Let’s start with what happens physiologically as we age, and how it can be affected by exercise.

We know that the untrained individual at the age of 60 has half the muscle fibers of an untrained 20 year old. This difference is less in trained people. However, we continue to gradually lose cells from our 30s and on, including in muscles, bones, joint cartilage and spinal discs, nerves and blood vessels etc., which usually becomes more noticeable after the age of 50.

Exercise can minimize this cellular decline and maximize our functional capacity throughout our lifespan, as well as minimize chronic low grade inflammation in tissues (which also adds a preventive effect against many chronic diseases) and pain.

The general formula is this: Too little, or too much/too intense exercise both accelerate the natural process of degeneration (“wear and tear”) in e.g. joints and spinal discs (arthritis and disc degeneration), tendons (chronic tears and tendinitis), muscles (weakness and atrophy), and bone (osteoporosis or fractures). The key is moderation. As we grow older, moderation means modifying our exercises, especially after the age of 50.

As bone weakens, we need to stimulate it with weight bearing exercise (against gravity) and resistance exercise. The ideal stress for bone is jumping or impact, but that becomes excessive for tissues such as joint cartilage and spinal discs, and is therefor typically not recommended after the age of 50-60, especially if we have a strong family history of arthritis or spinal conditions, or we have been diagnosed with such ourselves. Lower impact weight bearing exercise is therefor a better choice.

Joints need movement to lubricate our joint cartilage and keep the surrounding connective tissues pliable and strong. High repetition/low intensity work, such as bicycling, swimming and walking can accomplish this. Mild to moderate on and off joint compression stimulates the joint cartilage and spinal discs, such as what we get with pain free resistance exercise with gradually decreasing weight and increasing repetitions as we grow older.

A healthy 30 year old person can usually tolerate weight training with 90% or more of maximal resistance (if so desired), which would be possible to repeat 3-5 times in a set. A 40 year old would often be advised to limit the resistance to 75-80% of max, performed in 10-15 repetitions. The 50 year old would be wise to further reduce the resistance to 70-75% of max, with exercise repetitions of 15-20 per set. As we turn 60, a better yet intensity would be 60-70% of max, possible to move 20-25 times per set. These are general guidelines only, and there are individual variances between people, and the type of exercise performed. The principle is what is important here.

Excessive exercise dosage at older age almost always results in accelerated tissue aging with pain, injury, or premature joint replacement surgery. As we always need to keep a substantial energy reserve to build up new muscles while we are resting, and we lose muscle as we grow older and therefor also energy reserve, we also need to look at the overall volume of exercise (although high intensity exercise depletes this energy reserve the fastest). One way would be to perform weight training only twice a week, and even limit sets to two per exercise. Remember that exercises actually break down muscle tissue, and it is the rest afterwards which builds up new and stronger muscle fibers.

With regards to the above exercise prescription’s effect on muscle strength, we know today that we can develop almost as much muscle strength, girth and definition by performing higher repetition/ lower resistance exercise, as we would with low repetition/ high resistance exercise, as long as we avoid rest between exercise repetitions, so that we experience obvious muscle fatigue (a degree of muscle burn) as the muscle starts to “run out of oxygen”. This creates a stimulus for both slow twitch and fast twitch muscle fibers to contract, while also building additional small blood vessels to feed the muscles (capillarization). Thus, we can build both muscle strength and endurance, while also improving elasticity and strength of tendons (high repetition exercise needed for this).

Balance usually gets worse with older age, in part because we lose strength, and also because we lose nerve fibers which help us with position sense and coordination. The encouraging thing is that we can also build such nerve fibers by incorporating agility and coordination exercises throughout life. This can be accomplished by many forms of exercise. The key is that we have to control the movements ourselves, and not simply use machines which determine how we move. Various forms of balance exercise can be effective, but we also need exercise with well controlled movements, to fully develop our coordination and balance with functional activities in life.

Flexibility is desirable throughout life, which has to do with elasticity of connective tissues in muscles (and muscle tone or tension). Gentle muscle stretching for 10 seconds after we have warmed up, or at the end of workouts, can safely improve or maintain flexibility. However, we also know that excessive stretching, or stretches held for 20-30 seconds temporarily weakens the muscle, and may predispose you to muscle injuries, especially if done without proper warm up, or right before an explosive or demanding physical task. Therefor, it’s safer to perform most static stretches at the end of workouts.

A recently published research paper looked at blood biomarkers of low grade chronic inflammation, in people who had performed resistance exercises and aerobic exercise, versus people who had not. The researchers found that the biomarkers in the group of people who exercised indicated significantly reduced low grade chronic inflammation, compared to the sedentary people. Such inflammation not only tends to increase our perception of pain, but also increases the risk of developing chronic disease such as cardiovascular disease and diabetes. Eating an anti-inflammatory diet is also important, which is beyond the scope of this article.

It is generally recommended that we exercise at least 3-4 times per week, throughout life. The higher the intensity of exercise, the more rest we need between workouts, especially as we grow older. Lower intensity exercise such as walking, bicycling and swimming, can usually be done every day, if we want.

Whereas the above information has mostly stressed the beneficial effects of exercise on the neuromusculoskeletal system, a few comments can be added about high intensity cardiorespiratory (aerobic/anaerobic) endurance exercise. High level endurance athletes have a higher incidence of colds and respiratory ailments, as well as heart atrial fibrillation, than the general population. The increased infection rate is believed to be due to prolonged intense endurance exercise suppressing the immune system. Such athletes who exercise in cold temperatures, e.g. cross-country skiers. also have a higher incidence of asthma. The take home message here for all of us could be to go easier if we feel overly fatigued, and in particular if we feel like we could be coming down with some bug, in which case complete rest would likely be the best medicine.

A final piece of known statistics is that high level athletes in many demanding sports, such as American football, soccer and skiing to just mention a few, undergo more joint replacement surgery later in life, than the general population, presumably due to injuries and the high physical demands of the sports, exceeding their joints’ tolerance to forces even at a younger age. However, competitive sports have so many positive effects on a person’s development in life, in my opinion, while contributing a wonderful entertainment value to all of us spectators.

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