The heart-lung complex is critically important to movement. Both organs are essential to a functional lifestyle — ignore either, or both, and pay a heavy price.

This article will give you an overview of some of the pertinent facts about your muscles, which collectively comprise a system of your body that (just like your car) can be kept running at its operational best through proper and regular servicing. In this instance, you’re called on to do your own servicing. The good news is that the steps involved in properly servicing your muscular system are relatively straight-forward: Adhere to a nutritionally sound diet (i.e., eat a well-balanced diet and minimize your dietary intake of fat), don’t overly stress your muscles at work or play and engage in a sound strength-training regimen on a regular basis.

With regard to making sound strength exercise a regular part of your conditioning regimen, the following 50 facts about your muscles and strength training will give you a better understanding of what your muscular system is, how it is interrelated to the other systems in your body, why it is important to take care of and what you can do to help keep it in tip-top condition.

1. More than a few. The human body has more than 650 muscles.

2. The issue is tissue. Skeletal muscle is the body’s largest tissue, accounting for approximately 45 percent of body weight in men and 36 percent in women.

3. A miniature Charles Atlas. Muscles are comprised of muscle fibers. Each fiber is thinner than a human hair and can support up to 1,000 times its own weight.

4. Nature’s poetry in motion. Every human movement, whether simple or complex, is a sequence of skeletal muscle contractions woven seamlessly together by means of a complex interplay between the body’s muscles and the nervous system.

5. Special muscle, special task. Classified according to the duties it must accomplish in the body, there are three distinct types of muscle — cardiac, smooth and skeletal.

6. The heart of the matter. Cardiac muscle, found only in the heart, is responsible for the lifelong pumping action of the heart. Cardiac muscle fiber is short, branching and completely encircled by a membrane. Cardiac muscle cells are tightly bound together with membranes so permeable to electric impulse that they act as a mass of merged cells.

7. Smooth as a baby’s bottom. Smooth muscle consists of slender, cylindrical fibers that are aligned parallel to form sheets of muscle. Most smooth muscle is visceral (i.e., it surrounds nearly all of the body’s organs).

8. Patterned for power. Skeletal muscle fibers are elongated cylinders that contain several nuclei. These fibers are bundled into groups, which are then bundled together to form what most people refer to as “muscle.” Anchored to bones, skeletal muscle pulls on them to initiate movement.

9. It’s a fact — contract. Until the mid-20th century, most scientists assumed that when a muscle shortened, its components did too, thereby resulting in contraction (movement). In 1954, however, two research teams (one from MIT and one from Cambridge University) discovered that when muscles contract, the filaments within each muscle fiber actually slide past each other. Known as the sliding filament theory, their findings serve as the basic explanation for the process of muscular contraction.

10. Moving and grooving. A muscle moves by contracting. And by its motion, you move. As a machine for moving, a muscle is relatively efficient. It normally uses about 35 to 50 percent of its potential energy.

11. Feeling strong about getting fit. Proper strength training has numerous benefits, including developing muscular strength and muscular endurance, increasing muscle mass, improving bone mineral density and increasing the level of strength in connective tissues.

12. Recipe for success. The American College of Sports Medicine recommends a strength-training program that includes a minimum of one set (eight to 12 repetitions) of eight to 10 exercises that condition the major muscle groups, performed at least two days per week.

13. Where did the strength go? By the age of 65, individuals who haven’t engaged in exercise on a regular basis may incur a decrease in their muscular strength level by as much as 80 percent.

14. It’s all or nothing. When an individual muscle fiber is stimulated, it contracts to its fullest extent.

15. Making mama fit. Most experts agree that based upon the limited data available, proper strength training poses little risk to either the mother or her developing fetus. As a matter of fact, strength training may be very beneficial for a pregnant woman (i.e., provide her with the muscular fitness required to compensate for the postural adjustments that typically occur during pregnancy).

16. What you do is what you get. Depending on the type of response required of a muscle, stressing your musculature can elicit improvement in either muscular strength (the ability of a muscle or a muscle group to exert maximal force one time) or muscular endurance (the capacity of a muscle or a muscle group to resist fatigue and/or make repeated submaximal contractions).

17. Beyond your control. How much an individual can lift is influenced by at least seven factors: strength-training program intensity, predominant muscle fiber type, hormonal levels, body proportions, tendon insertion points, muscle-tendon ratios and neurological efficiency.

18. How much is more? All other factors being equal, an individual who moves 200 pounds a distance of two feet has done more than a person who lifts 300 pounds one foot.

19. Weighing the truth. The optimal exercise program for controlling your weight is one that combines aerobic conditioning and strength training. Such a prescription allows you to expend a relatively large number of calories, while simultaneously preserving or increasing your level of lean muscle mass — the tissue that has the highest resting metabolic (calorie burning) rate.

20. The pain of it all. Two types of muscle soreness exist — acute and delayed. Acute soreness occurs during and immediately following physical activity. Delayed soreness occurs well after the exercise bout is completed, and typically peaks in intensity within one to three days following unusually vigorous or unaccustomed exercise. Acute soreness is believed to be a byproduct of impeded blood flow and the accumulation of waste products in the muscle. Delayed soreness is thought to be the result of small amounts of structural damage (microscopic tears) to the muscle fibers and connective tissues.

21. Yes, she can. Women can and should get strong. Since the admission of women to West Point in 1976, for example, that institution has had several women graduates who could perform more than 100 straight-back push-ups (the so-called “male push-up”) in two minutes, including one woman in 1990 who did 132 push-ups in two minutes.

22. No pain, no gain, no sense. No evidence exists that a sensible strength-training program should be painful. Uncomfortable, perhaps — but not painful. There’s a difference between pain and discomfort. Pain is your body’s way of telling you that you’re doing too much. Discomfort is simply a signal that you’re doing more than you’re used to doing.

23. Power loss. Muscular dystrophy is a disease that literally “robs” a muscle of its power. Muscular dystrophy is a broad term applied to a group of nine disorders that act in much the same way. They are characterized by weakness and wasting of skeletal muscles. Each type of the disease differs in the muscles affected, the age at which it begins and the rate of its progression.

24. Making your bones move. Your muscles are attached to your bones by connective tissue called tendons. The contraction of a skeletal muscle generally causes one bone to move though a specific range of motion toward another bone. The bone that remains fixed (stationary) is considered the site of the muscle origin, while the bone that moves is referred to as the site of the muscle insertion.

25. Training for a purpose. The basic methods of strength training are generally grouped into five classifications: isometric (you contract your muscle, but the involved joints don’t move); isotonic (the amount of external resistance does not vary while you are exercising); eccentric-only (exercise involving muscular contractions in which the muscle only lengthens); isokinetic (exercise which involves a constant state of speed of movement); and variable resistance (exercise in which the resistance accommodates to the strength curve of the muscle being stressed).

26. Nature’s way of choosing. Skeletal muscle has two distinct types of fibers — fast-twitch and slow-twitch. Classified by their contractile and metabolic characteristics, these fibers are believed to have an impact on your “trainability” for certain activities. Fast-twitch fibers (also known as Type II fibers or white fibers) are generally involved in short-term, anaerobic activities. Slow-twitch fibers (also termed as Type I fibers or red fibers) are relatively fatigue-resistant and well-suited for prolonged aerobic activity. If you have a preponderance of one type of fiber, you tend to be somewhat predisposed for success in activities that involve that type of fiber.

27. Gone, but not forgotten. By the age of 80, sedentary individuals will lose about half of their muscle mass.

28. Unique in its own way. No two muscles in your body have exactly the same function. When any one muscle is paralyzed, either stability of the (body) part is impaired or some specific movement is lost.

29. Good medicine. Recent research suggests that sound strength training can have a positive effect on cardiac rehab patients.

30. The recipe for making skeletal muscles. Approximately 75 percent of skeletal muscle is water, 20 percent is protein and the remaining 5 percent is made up of inorganic salts and other substances.

31. The impulse to move. The functional unit of neuromuscular control is called a motor unit. A motor unit consists of a single motorneuron and all the muscle fibers it innervates. Motor units vary widely in size. For example, the first dorsal interosseous muscle of your finger contains 120 motor units that control 41,000 muscle fibers, whereas your medial gastrocnemius muscle (calf) has 580 motor units and 1,030,000 muscle fibers.

32. Increasing the ante. During exercise that requires an oxygen uptake of 4 liters per minute, the muscle’s oxygen consumption increases nearly 70 times over its resting requirements.

33. Making sense from nonsense. It’s a myth that when you stop strength training regularly (for whatever reason) that your muscles will turn to fat. Muscles cannot turn to fat. Muscle and fat (adipose) are two separate and distinct tissues that do not have the capacity to change from one type to another.

34. The “meat” of the matter. Extra protein will not enhance your efforts to build larger muscles. Your body is unable to store extra protein. If you consume protein in excess of your caloric and protein needs, any extra protein will either by excreted or converted and stored as fat.

35. Stronger bones, fewer fractures. Strength training can have a positive effect on osteoporosis. Load-bearing exercise, performed over an extended period of time, increases bone density. The pressure applied to bones as the result of gravity, muscular contractions and the demands of resistance exercise encourages calcium to deposit in bones.

36. A matter of hormones. Women simply don’t have the genetic potential to develop bulky muscles. They don’t have sufficient amounts of testosterone — the hormone largely responsible for the development of muscle bulk.

37. Be the best you can be — nothing more and nothing less. Strength training should not be a contest — against anyone else or yourself. If you focus on the competitive aspects of how much you lift, you increase your risk of either being injured or getting discouraged with the results of your efforts. The guiding principle to which you should prescribe is “to do your best and leave the rest.”

38. Please help me, I’m falling. Proper strength training can induce improvements in both muscular strength and balance, thereby helping prevent the falls that cause a substantial number of the fractures from which the elderly suffer.

39. More is not necessarily better. All factors considered, the “quality” of the strength-training exercise you perform is much more important than the “quantity” of time you spend strength training. If it wasn’t, the person who spent the most time in the weight room would always be the strongest — which is often not the case.

40. The time of your life. Maximum strength of men and women is generally achieved between the ages of 20 and 30 years.

41. It’s not right to be tight. Proper strength training will not make you muscle bound. Muscle bound is a term which connotes a lack of flexibility. If you lift weights through a muscle’s full range of motion, not only will you become more flexible, you’ll be as flexible as genetically possible.

42. The ABCs of vitamin supplements. Strength training does not increase your need for vitamins. The vitamin needs of a physically active person are not appreciably greater than those of a sedentary person. Since vitamins do not significantly contribute to your body structure or provide you with a direct source of energy, you receive no benefit whatsoever from ingesting vitamin supplements — provided you normally eat a wide variety of healthful foods.

43. Beauty is in the eye of the beholder. Strength training cannot produce spot reductions in areas of your body. Strength training, however, can firm and help reshape different muscles and areas of your body to elicit a more fit look.

44. All the rage at any age. All other factors considered, adolescents can derive numerous benefits from participating in a sound, supervised strength-training program. Research has shown that the positive consequences of such training far outweigh the potential risks.

45. A breath of common sense. Breathing properly is a basic safety consideration while strength training. A fundamental precept to which you should always adhere is to never hold your breath while strength training. Holding your breath results in a potentially dangerous buildup of intra-thoracic pressure. This pressure (inside your rib cage) compresses the right side of your heart, which in turn restricts the flow of blood and oxygen to your entire body.

46. Balancing act. Your strength-training program should emphasize muscle balance. In your body, you have muscles that oppose each other (e.g., your quadriceps muscles are opposed by your hamstring muscles). These muscles have a proportional strength relationship between them. If one is much stronger than the other, you run the risk of injuring the weaker muscle.

47. It makes sense to be intense. In order for improvement to occur in your strength level, you must place a demand on your muscular system. No demand, no improvement.

48. It’s insane to over-train. Part of the “art” of prescribing strength fitness exercise is the ability to design your program in such a manner that it provides a sufficient training stimulus to induce positive physiological changes without exceeding your body’s capacity to safely adapt to that stimulus. In other words, you need to achieve an appropriate balance between training and recovery.

49. With a little help from your friends. Individuals who strength train with a partner tend to achieve better results. A training partner can help ensure that you perform each exercise correctly and that you exert a more intense effort.

50. A tune-up for life. Because muscular fitness is a critical component of functional fitness, strength training must be an essential part of your workout regimen. The better you keep your muscles tuned up, the better they will function and the longer they will operate effectively and efficiently.

Technical masterpieces

Your muscles are merely tissue, but no less valuable than the rarest of jewels. Proper resistance exercise can help sustain their bountiful offering of benefits for your lifetime.

By Cedric X. Bryant, James A. Peterson & Ronald Hagen

Editors of Prevention Magazine. Prevention’s Giant Book of Health Facts. Emmaus, PA: Rodale Press, 1991.
McArdle, William D., F.I. Katch & V.L. Katch. Exercise Physiology: Energy, Nutrition and Human Performance. Philadelphia, PA: Lea & Febiger, 1991.
Peterson, J.A., & C.X. Bryant (eds.). The StairMaster Fitness Handbook. Indianapolis, IN: Masters Press, 1992.
Powers, S.K, & E.T. Howley. Exercise Physiology (2nd ed.). Madison, WI: Brown and Benchmark Publishers, 1994.
Sharkey, B. Physiology of Fitness (3rd ed.). Champaign, IL: Human Kinetics Publishers, 1990.

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