Health Courses->Exercise Basics->Strength
The strength of a muscle refers to how much force it can generate. There is also the factor of muscular endurance, which is the ability to perform low-intensity work over a sustained period of time. Power refers to performance of work per unit of time. This is calculated by multiplying force times velocity of motion. There is also tensile strength of tissues, which is the ability to resist tearing or forces pulling apart. Resistance to compression forces in bone needs a certain type of strength, too. In non-technical, holistic health terms, we want to be strong enough to engage in all the desired activities of daily living without fatigue or risk of injury.
Improvement of one’s strength comes about by challenging the tissues to ever-increasing, graded exercise that stresses the tissues sufficiently to stimulate an adaptive response to the challenge—Muscles grow in size, blood vessels expand to bring more oxygen, and nutrients to the area, ligaments and tendons change their internal structure, and bone increases its matrix of living cells and minerals.
The Benefits of Strength
Improving all these types of strength produces many health benefits. It can give us more livelihood, social and recreational opportunities, raise self-esteem, and provide more variety in our lifestyle.
Strength protects against injury and the process of aging. One of the most frequent causes of incapacitating back pain is weak muscles.
Ninety-eight percent of all people with back problems have weak spinal musculature.
Osteoporosis, or the demineralization and weakening of bones with age, can be greatly reduced by activities that promote strength. Any muscular effort stimulates bones that the muscles pull against to increase their mineral content and the substances that connect the minerals into strong shapes. So when we talk of strength training we refer primarily to the direct strengthening of muscles and the consequent strengthening of the bones.
50,000 of our elders will die from hip fractures and their complications.
The elderly fall and break their hips and other bones because their leg muscles are weak from lack of proper exercise. Ninety year olds have three times less thigh muscle mass than they did at 20 years of age. Proper strength training exercise at 60, 70, 80, 90, or even 100 can produce important increases in strength. Not only is balance improved, but the increased muscle mass from strength training reduces the percentage of body fat.
Assessment of Strength
The first level of strength assessment is just asking oneself “Am I a weenie?” If the answer is yes then some sort of strength enhancement is recommended. There are more sophisticated tests than this but if you fail this one further testing will just determine degree, or “weenie factor” in technical terms. More detailed testing of strength is valuable in many individuals.
Sub-maximal testing with strength training equipment at gyms or at home can provide valid testing data for the average person to start a strength training regimen, periodically retest progress, and alter the training protocols accordingly for effective strength improvements. Self-motivated individuals can use the recommended resources to accomplish this. But there are, fortunately, sufficiently informed personnel at most gyms who are more than willing to assist those needing help in the proper use of strength training testing, equipment, and procedures. Some of the less knowledgeable personnel in gyms and spas convey improper information regarding strength training techniques. To guard against being misinformed one can reconfirm procedures with the guidelines presented here and by using the recommended resources.
For a large segment of the population though, more careful and precise forms of strength testing are advised. People who should approach strength training from this avenue would include:
- people recovering from a significant musculoskeletal injury, particularly of the spine
- those who have had a long period of inactivity which might make them susceptible to injury due to lack of conditioning
- those with significant alterations in flexibility, either very restricted mobility or excessive
- those with significant musculoskeletal handicaps
- elderly who are susceptible to osteoporosis, particularly inactive, post-menopausal women not using hormone replacement therapy
- those of any age whose athletic or work endeavors demand pushing their bodies to the limit of physical capabilities
There are a number of different facilities that do advanced strength and musculoskeletal testing. These facilities are equipped with a variety of instruments, many computerized. The best muscle and functional strength assessment equipment evaluates different types of strength in isolated muscles at all angles through which they work. They can identify certain types of weaknesses undetectable by more generalized and cruder mechanisms suitable for relatively healthy individuals. By finding these “hidden” weak points, special exercises can be prescribed to overcome them. Other instruments can evaluate bone density as a factor of strength.
They are supervised and operated by different combinations and quality of health professionals — chiropractors, physical therapists, exercise physiologists, and doctors specializing in physical medicine. One group that works for quality control in medical facilities is the Commission on Accreditation of Rehabilitation Facilities, 101 N. Wilmot Rd., Suite 500, Tuscon, AZ 85711; (602) 748-1212.
Principles of Holistic Strength Training
When we speak of holistic strength training we are, in part, implying that there is a level of adequate strength and that this strength be balanced. We want to focus our priorities on how much strength we need to safely and efficiently carry out any of the day’s activities. There is no need to engage in a regimen involving bench pressing 400 pounds if you are never going to require your body to even approach those levels of achievement on a day-to-day basis. Holistic strength training is designed to produce and maintain strength at a level which will support all the other aspects of life.
Too often people get carried away with one aspect of fitness improvement, and this distorts other aspects and priorities in their lives. Many body-building enthusiasts display such an imbalance. There are some physical and many psychological reasons for enjoying ever-increasing strength and muscular bulk beyond what is holistically needed. That is why it is important to carefully and continually assess the goals of any self-improvement program if the overall goal is holistic health and stress management. Otherwise some minor priority like heightened sexual attractiveness might overtake and obscure the big picture.
Balance in strength can be looked at several ways. There is a balance between strength and flexibility which is very important. The excessively bulked-up body builder who lacks a proportionate flexibility is a typical example of this. In reality, high levels of strength training and muscular development can and should come about with increased flexibility. Proper pre- and post- stretching routines should complement strength training.
Balance can also refer to an equality of strength between left and right pairs of muscles. Many people engaged in irregularly balanced activities, either at work or at play, can develop left-right strength imbalances so significant they put them at risk of injury. Laborers, like carpenters or landscapers who are predominantly one-sided in their activities—hammering, sawing, raking, shoveling—many times have visibly larger muscles on that side. An accident is often just waiting to happen. Developing the weak-sided muscles assures better biomechanical function and improved neuro-muscular coordination.
A less noticeable strength imbalance, but not less frequent, is that between muscles and their antagonists, and/or stabilizers. Muscles that act as primary movers of a joint are termed just that, primary movers, or agonists. Muscles that stabilize the joint complex while the primary movers act to produce the desired motion are called stabilizers. Antagonist muscles are the muscles that counteract the force and motion of the primary movers. They must be neurologically signaled to relax at the same time the primary movers and stabilizers are signaled to contract. A confusion in nerve signaling, altered flexibility of the tissues or joints, or excessive tone or weakness of the antagonists, will cause problems.
There are now scientific calculations on specific muscle strength ratios that are healthiest — back extensors to abdominals, quadriceps to hamstrings, various shoulder girdle muscle ratios. There are even differences calculated for maximal performances in different sports—the quadriceps to hamstring ratios should be different between runners and cyclists, and rowers have different ideal strength ratios in the shoulder muscles than baseball pitchers.
Elements of Proper Strength Training Techniques
Isokinetic and isotonic strength training exercises are superior to isometric types of training. Isokinetic and isotonic exercises involve moving a joint against some resistance through the joint’s entire range of motion. The resistance can be in many different forms: free weights (dumbbells and barbells), pulley system weights (Universal Gym, Isolator, and Nautilus type equipment), hydraulic systems (Unex and others), surgical rubber tubing, “the most cost-effective strength training system” (Lifeline Gym, Medi-Cordz, Theratubing, Xercise Tube, and Thera-Band), isokinetic machines (Cybex, Biodex, Lido, Kin-Com, and Fitnet), and using a partner to provide the resistance. These build the strength of muscle cells throughout the length of the muscle. Isometric exercise of a muscle means contracting it against resistance without moving the joint. Muscle cells are then stimulated to strengthen in only one portion of the muscle. Isotonic exercise involves keeping equal tension on the muscle throughout the entire range of movement. Isokinetic exercise involves moving the joint through an entire range of motion at a steady rate of speed while keeping maximum tension on the muscle.
Muscle strength can increase during both the contracting phase and the relaxing phase of resistive exercises. The contracting phase, when the muscle is shortening, is termed concentric contraction. It is usually the act of lifting a weight. Eccentric contraction is the term used when the muscle is lengthening. For holistic strength training purposes, concentric contractions are preferred over eccentric because there appears to be more tissue damage and muscle soreness from eccentric exercise. More rest time is also required between exercise sessions when doing eccentric exercise. Competitive athletes sometimes like to use eccentric exercises because these can sustain the greatest forces, thus stimulating maximal strength. Unfortunately, injuries increase with these escalating tensions.
Although some of the best strength gains come when taxing muscles to 90% of their maximal capacity for work, it is difficult to tell when 90% maximal effort is actually taking place. This encourages training to absolute fatigue. Unfortunately, it also threatens the health of the muscle. The likelihood of injury increases as greater tensions and weights accumulate, and also as fatigue sets in. Egotistical urges to push to the upper limits are not conducive to preventing injuries or obtaining holistic health.
“Slower is safer” is another rule of thumb that serves holistic strength training well. Rapid, ballistic maneuvers are known to produce power more than slow movements. In some sports-specific exercises, these quick, powerful contractions are needed to perform the desired activities (Boxing punches and vertical leaps in volleyball are examples). Unfortunately, these quick, forceful bursts produce very small muscle tears every time they are performed. They can also lead to more serious tearing injury to the muscles and tendons. In resistive types of exercise it is wise to contract a muscle concentrically for a slow count of two and contract eccentrically for a slow count of four.
The number of repetitions needed to contract a muscle to 90% of it’s capacity for work varies depending on the amount of resistance. The greater the resistance, the fewer repetitions needed to induce fatigue. For holistic strength training purposes it is wise never to use a resistance so great one cannot perform 8 repetitions. The forces and risk of injury become too great. Super fit athletes, body builders, power lifters, often use high resistance with as few as one repetition for maximal strength gains. Remember that maximal performance is different from optimal health. Upper body resistance exercises for strength usually require 8-12 repetitions for good improvement. For lower body and trunk 12-20 repetitions is usual. For endurance gains lighter resistance is used with higher repetitions in the 40-80 range. In one exercise session one muscle group can be contracted for the desired number of repetitions and then after a short rest this can be repeated. This is termed “doing multiple sets” of an exercise. There are different opinions about the degree of benefit from doing multiple sets.
Sufficient rest time after each session of resistive training is a must. Strength gains do not occur during exercise; they occur during the rest periods between exercises. Some people need longer rest intervals than others. At least 48 hours of rest between successive bouts is mandatory. Some athletes will exercise different muscle groups on different days so that they can train on successive days. They might have 2, 3, or 4 different routines, each working different groups of muscles. They then rotate the routines in such a way that they give plenty of rest to muscles but also re-stimulate them in sufficient time to continue strength gains. A once-a-month visit to the gym to pump some iron won’t cut it. In order to make significant improvements in strength, a six week period of three exercise sessions per week is usually required. To maintain strength, challenging the muscles in two sessions per week is typically necessary.
There are an infinite number of different combinations of resistance, repetitions, sets, frequency, rest, and exercise equipment. In the arena of maximal performers such as competitive body builders and power lifters, football players, and hammer throwers, there is much discussion of which combination is best. For those seeking well-balanced, optimal, holistic health, the debate over the details and nuances of strength training is irrelevant. Engaging in a strength training regimen within the recommended parameters set forth here is adequate. Remember though, that these recommendations include seeking qualified assistance when needed. And the importance of balancing strength training with aerobic conditioning, flexibility exercises (At least 10 minutes of stretching before and after a strength training session is absolutely necessary), and coordination activities, is essential.
Kisner, Carolyn and Colby, Lynn. Therapeutic Exercise: Foundations & Techniques. Davis, 1990. Oriented towards exercise therapists but great for well-educated individuals wanting one source for excellent exercise protocols.
Make sure that you have sufficient strength to protect yourself from life’s daily demands. If not, engage in a wise program for strength enhancement, with supervision if necessary.