Strength training involves using progressive resistance to increase a person's ability to exert or resist force. It usually involves use of free weights, weight machines, elastic tubing, or one's own body weight.
Strength training also is known as resistance training. Resistance exercises may be used to help patients restore function to injured muscles or to build muscle around injured bones and joints to improve function.
Studies have confirmed that people who engage in some form of physical activity through their lifestyle or occupation will likely live longer and have healthier lives. Regular exercise has been linked to weight reduction, lowered blood pressure, improved glucose regulation, stronger bones, and better lipid profiles. Strength training can help slow and possibly reverse muscle decline. Strong muscles lessen the workload on the heart. Recent studies have found that strength training can improve quality of life for people with mild and moderate chronic obstructive pulmonary disease (COPD) and for indviduals with multiple sclerosis.
Strength training appears to help people of every age. Research on the positive effects of strength training in the elderly has been around for quite a while. Structured weight training and physical conditioning programs can help reduce pain and prevent the normal physiologic decline associated with aging. Even nursing home patients can benefit from appropriate strength training. While some parents may worry that strength training is dangerous for their children, a well-designed program may help improve a child's health and fitness without causing increased muscle bulk.
A 2005 study reported that strength training helped improve how women with characteristics of eating disorders perceived their body size. Strength training has been shown to reduce the signs and symptoms of a number of diseases and chronic conditions, including:
- back pain
Athletes benefit from strength training as well. Proper strength and conditioning can increase athletic performance, improve physiological function, and reduce risk of injury. Resistance training can reduce stress on the skeleton and produce favorable changes in body composition.
When an athlete or any person receives a musculoskeletal injury, strength training may be part of the rehabilitation process.
Pregnant women or people with certain medical concerns, such as chest pain or other heart conditions, severe dizziness, certain bone or joint problems, and who take prescription medications for high blood pressure or heart conditions, should consult their physicians before beginning any exercise program. Strength training exercises can cause injuries if not performed correctly or if performed without proper supervision. Most injuries appear to occur because too much weight is added too quickly or improper technique is used.
Strength training often is confused with body building and power weight lifting. While these efforts use many of the same concepts and equipment, their goals may not be the same and should not be confused with strength training.
The body has four basic types of muscle contractions. Strength training programs often are designed around these contraction movements.
- Dynamic, isotonic, or concentric. The muscle becomes shorter and tension varies as it lifts a constant load.
- Isometric or static. The muscle does not change length even though tension develops.
- Eccentric. The muscle develops tension, lengthening while contracting.
- Isokinetic. Maximal tension develops while the muscle is shortened at constant speed over the full range of motion.
Strength training generally involves use of free weights, elastic resistance bands, or equipment that holds weights or produces measured resistance. A planned program calls for beginning at the appropriate lower weight or resistance level and in controlled movement, exhaling when exercise is hardest and inhaling when it is easiest. The person will do several repetitions (reps) of the same movement with the same amount of weight. This constitutes a set. Usually, a set consists of five to eight reps and a person performs one to three sets per training session. However, the number of reps and sets varies, depending on many factors. Most people will repeat each set on both sides of the body (for example, biceps curls with the right and left arm). This may not be the case in rehabilitative sports training. For instance, when strengthening an injured ankle, the exercises may be performed only on the injured side or the amount of weight/resistance or repetition may vary from one side to another. The training should be done several times a week. Most experts recommend a day of rest between strength training sessions to allow the muscles to recover.
If the goal of the training is improving strength for injury rehabilitation, a physical therapist may prescribe very low weight at the beginning. In most cases, exercise physiologists and strength training specialists set differing goals depending on a person's age, physical abilities, and program goals.
Many people considering strength training will need to check with their physician before beginning the program. An exercise or physical therapy professional can recommend the proper amount of weight or resistance to begin training. People considering weight training also should purchase good athletic shoes with adequate support, and loose, cool, comfortable clothing that absorbs moisture.
It is important to rest between strength training sets and to stretch after completing all exercises. It also is important to stop exercising at any time if pain is experienced.
Injuries can occur from lifting weights that are too heavy, from using improper technique, or from other unsupervised strength training. Poorly designed equipment may cause injury. Muscles build up can occur from power lifting of heavy weights over extended time.
Numerous studies document the beneficial results of properly conducted strength training. Older adults often report improvements in pain and function within less than two weeks of starting a strength-training program. A study of people age 61 to 82 years who participated in weight and aerobic training twice a week for 75 minutes over 24 weeks showed 16-17% increase in upper-body strength for men and women. A 12-month study of postmenopausal women at Tufts University who underwent progressive strength training two days a week reported 75% increases in strength, 13% increases in dynamic balance, and 1% gains in bone density. A control group experienced losses in strength, bone, and balance.
Health care team roles
Health professionals in nursing, rehabilitation, occupational therapy, and physical therapy may specialize in some aspect of strength training as part of their jobs. Some orthopedic surgeons specialize in sports medicine, overseeing the conditioning of athletes, as well as injuries related to a variety of professional and recreational sports. Exercise physiologists become versed in the science behind exercise, muscle, and movement. Personal trainers and other strength training professionals may assist a person with their program. There are certification programs available for these professionals.
Foss, Merle L., Steven J. Keteyian. Fox's Physiological Basis for Exercise and Sport. WCB/McGraw-Hill, 1998.
Kruger J, et al. "Strength Training Among Adults Aged (greater than or equal to) 65 Years—United States, 2001." Pediatric News (Feb. 2005):23.
MacReady, Norra. "Strength Training Helps Fitness, Coordination." Morbidity and Mortality Weekly Report (Jan. 23, 2004):25-29.
Panlaqui, Ogee Mer A., et al. "Tolerance and Quality of Life Improvement Following Aerobic and Strength Training Exercise in Patients With Chronic Obstructive Pulmonary Disease." Chest (Oct. 2005):253S-255S.
"Strength and Power Training Essential to Exercise Regimen, According to Report." Heart Disease Weekly (Jan. 18, 2004):41.
"Study Shows Weight Training Gives MS Patients Physical, Emotional Benefits." A Scribe Health News Service (Jan. 13, 2005).
Sullivan, Michele G. "Weight Training Prevents Muscle Decline, Eases Pain in Elderly Patients." Family Practice News (Sept. 1, 2005):64.
Sullivan, Michele G. "Self-image Improves With Strength-Training Program." Family Practice News (July 15, 2005):1-2.
"The Promise of Strength Training: Are the Frail Elderly Past Beneficial Strength Building? Think Again." Nursing Homes (Sept. 2004):S6-8.
"Weight Training May Be Effective for Body-imaged-disturbed College Women." World Disease Weekly (Nov. 23, 2004):125.
American College of Sports Medicine. PO Box 1440, Indianapolis, IN 46202. (317) 637-9200, ext. 138. 〈http://www.acsm.org〉.
Growing Stronger-Strength Training for Older Adults: Why Strength Training? Web page/brochure. Centers for Disease Control and Prevention, 2005. 〈http://www.cdc.gov/nccdphp/dnpa/physical/growing_stronger/why.htm〉.
Selecting and Effectively Using Free Weights. Web page/brochure. American College of Sports Medicine, 2003. 〈http://www.acsm.org/health+fitness/brochures.htm〉.