Article

Muscle Strength is More Important Than You Know

Man leaning over railing and stretching near the ocean

Importance of Maintaining Muscle Strength

Strength increases naturally during adolescence and early adulthood. About the age of 30, strength starts to slowly decline. This decline starts to accelerate at about 50 years of age resulting in a 16% decline over the next 20 years. At approximately 70 years of age the rate of decline accelerates once again to about a 25-30% loss per decade. This decline in strength is associated with a loss of muscle mass, although other factors such as a reduction in neuronal recruitment of muscle fibers have been implicated.

Muscle strength is a major component of physical fitness. Other components include cardiorespiratory fitness and body composition. It has long been established that cardiorespiratory fitness is related to future cardiovascular and heart health concerns. Strength or the loss of strength is general associated with frailty, weakness, reduced mobility, functional disability and injuries due to falls. However, over the last 5 to 10 years researchers have found a high correlation between muscle strength and cardiovascular and immune system health, as well as maintaining healthy body functions. For example, the Prospective Urban Rural Epidemiology (PURE) study, a study encompassing154,000 community-based individuals from 17 high-income, middle-income, and low-income countries, found that grip strength was inversely associated with all-cause mortality and cardiovascular mortality.

The reason for the association between strength and overall health and well-being or mortality are not known. Loss of strength is usually associated with increases in fat mass. So it was initially reasoned that changes in body composition associated with strength loss contributed to the relationship between strength, health issues, and life expectancy. To address this premise, 800 men and women 64 years of age and older were screened for grip strength and body composition and followed for 24 years. The results, however, indicated that regardless of an individual’s body composition and fat mass, strength was a long-term predictor of all-cause mortality. In a separate 20 year epidemiological study, similar results were also found when strength was quantified by combining leg press and bench press strength in individuals 20 to 80 years of age. The results indicated that whole body strength was related to all-cause mortality, and regardless of the body mass index (a measure of fatness) of the subjects. In addition, when the results were adjusted for initial cardiorespiratory fitness, strength remained associated with all-cause mortality. Finally, it has been reported that among healthy 45 to 65 year-old men, strength is highly predictive of functional limitations and disability 25 years in the future.

These studies firmly establish that strength is inversely and independently associated with age-related decline in health frailty, metabolic disorders, and all-cause mortality. Therefore, steps need to be taken to maintain strength, as one gets older.

One method of improving or maintaining strength is through weight training. With weight training, rapid gains in strength and muscle mass can be achieve in adolescences and early adulthood. Once middle-aged or older, developing strength and muscle mass becomes more difficult, however still possible. In fact, individuals incapable of ambulation due to muscle weakness have successfully increased their strength and become mobile with participation in appropriate weight training programs. In addition, weight training has been found to improve blood lipids, increase insulin sensitivity, and support cardiovascular health. Furthermore, weight training has been found to be as or more effective for fat loss as aerobic exercise. Therefore, maintaining one’s strength through weight training may help support cardiovascular and heart health as one ages, and improve quality of life.

Setting Up Your Weight-Training Program

The most effect way to maintain or improve muscle strength and mass is through a weight-training program. Below is some basic information on developing a safe and sound program that will help you meet you own personal goals.

Muscle strength is just one component of muscle fitness. Muscle fitness is defined as the ability of the muscle to provide sufficient force, in a timely manner, and to sustain that force as needed. The components of muscle fitness are strength, power and endurance.

  • Strength is a measure of the maximal force that can be produced by the muscle. This is usually determined by the amount of force a muscle can produce during an isometric contraction, or the maximum amount of weight the muscle can lifted for one repetition (1 RM).
  • Power is force divided by time or the rate at which force can be produced. For example, if one person can bench press a maximum weight of 200 lb. in 2 seconds and another individual can do this in 1 second, the second individual is more powerful.
  • Endurance is the third component of muscle fitness and is the ability to sustain force.

In developing a weight-training program it is best to concentrate on improving muscle endurance to start and then concentrate on developing muscle power and then strength in this order. To develop muscle endurance, one should work with a low weight, do a high number of repetitions per set and complete a moderate number of sets of each exercise. An example of a muscle endurance protocol would be to have the weight or resistance between 20-40% 1 RM, the repetitions per set between 12-15 and the number of sets 2-3. Starting with a program to develop muscle endurance, gives the muscles time to adjust to the new stresses place on them and limits the possibly of early injury. After you feel comfortable with the weights you are lifting, start to increase the weights per lift (exercise) and decrease the number of repetitions per set to work on developing power and then strength. To develop power, use a moderate resistance of 40-70% 1 RM for each lift. Use a moderate number of repetitions (8-10 repetitions) per set and do 3-4 sets. For strength development, the resistance should be between 75 to 90% of 1RM, the repetitions per set 3-8 and the number of sets per lift 4-5. During each repetition be sure to control the lowering of the weight with a slow, deliberate movement. Don’t just drop the weight back into position.

Here are a few considerations in developing your weightlifting program.

  1. Design your program to work all the large muscles in the major areas of the body. These areas include the chest, back, shoulders, arms, legs and abdominal region.
  2. Make sure you are doing the lifts correctly. Doing them incorrectly does not develop the muscles intended and may cause muscle pulls, strains and possibly serious injury. Make sure you are performing each lift through its full range of motion.
  3. Change your exercise program every 6 go 8 weeks to provide some variety in your program and prevent boredom. Changing lifts is also beneficial as gains in strength are very specific to how the muscle is being trained. So training muscle groups with different lifts or movements enhances strength gains.
  4. It is best to start your program alternating upper and lower body exercises such as performing biceps curls followed by front squats. With regard to time between sets, 1-2 minutes rest is sufficient.
  5. A good way to start your training program is with about 5 to 10 minutes of light aerobic exercise such as walking on a treadmill, and then finishing the warm up with a few upper and lower body stretching exercises.
  6. If using a whole body weightlifting program, limit your training sessions to every third day. This will give the muscles sufficient time to fully recover and will speed muscle development.
  7. If you set up a split workout (upper body lifts one day and lower body lifts another), limit your workouts to 4 per week. Off days can be used for light cardio workouts.

Below are several exercises that can be performed for each of the 6 major body regions that should be trained.

  1. Chest – dumbbell chest press, dumbbell chest fly, bench press, parallel bar dips, dumbbell pull-overs
  2. Shoulders – lateral raises, front shoulder raises, upright rows, shoulder press,
  3. Arms – dumbbell biceps curls, barbell curls, dumbbell hammer curls, dumbbell triceps extension (on back and standing), pull-downs, forearm dumbbell curls, forearm dumbbell reverse curls
  4. Back – freestanding T-bar rows, upright row, lat pull-downs, one-arm dumbbell rows, dead lift, barbell shrugs
  5. Legs – front squats, leg press, lying leg curls, leg extensions, seated barbell toe raises, dumbbell lunges
  6. Abdomen – high-pulley crunches, sit-ups, incline sit-ups, parallel bar leg raises

If you are unfamiliar with the exercises listed or you are not sure how to use certain pieces of equipment in your gym, consult a personal trainer. He or she will be more than happy to help you get started. There are also a large number of websites that provide information on developing weight-training programs and describe how to perform the lifts provided above.

References

  1. Demontis, F. et al. Mechanisms of skeletal muscle aging: insights from Drosophila and mammalian models. Disease Models & Mechanisms 6:1339-1352,2013.
  2. Frontera WR, et al. Strength conditioning in older men: skeletal muscle hypertrophy and improved function. Journal of Applied Physiology 64:1038-1044, 1988.
  3. Gale, C.R. et al. Grip strength, body composition,and mortality. International Journal of Epidemiology 36:228-235, 2007.
  4. Leong, D.P. et al. Prognostic value of grip strength: fi ndings from the Prospective Urban Rural Epidemiology (PURE) study. Lancet 386:266-273, 2015.
  5. Metter, E.J. et al. Age-associated loss of power and strength in the upper extremities in women and men. Journal of Gerontology 52:B267-B276, 1997.
  6. Ruiz, J.R. et al. Association between muscular strength and mortality in men: prospective cohort study. BMJ 2008;337:a439 doi:10.1136/bmj.a439.
  7. Taina, R. et al. Midlife hand grip strength as a predictor of old age disability. JAMA 281:558-560, 1999.
  8. Tan, B. Manipulating Resistance Training Program Variables to Optimize Maximum Strength in Men: A Review. Journal of Strength and Conditioning Research, 13:289-304, 1999.
  9. Tanasescu, M. Exercise type and intensity in relation to coronary heart disease. JAMA 288:1994-2000, 2002.