Muscular Strength And Endurance
Muscular strength and endurance are health-related fitness components that may improve or maintain the following:
- Bone mass, which is related to osteoporosis
- Glucose tolerance, which is related to type 2 diabetes
- Musculotendinous integrity, which is related to a lower risk of injury, including low-back pain
- The ability to carry out the activities of daily living, which is related to self-esteem
- The fat-free mass and resting metabolic rate, which are related to weight management
Muscular strength relates to the ability of the muscle to exert force. In other words, it is the maximal one-effort force that can be exerted against a resistance, or the maximum amount of force that one can generate in an isolated movement of a single muscle group. The stronger the individual the greater the amount of force that can be generated. Lifting heavy weights maximally once or twice, or exerting maximal force when gripping a hand dynamometer, provides measurements of muscular strength.
Muscular endurance is the muscle's ability to continue to perform for successive exertions or many repetitions. Traditionally, tests allowing few (<3) repetitions of a task prior to reaching momentary muscular fatigue have been considered strength measures, whereas those in which numerous repetitions (>12) are performed prior to momentary muscular fatigue were considered measures of muscular endurance.
Regular use of skeletal muscles helps to improve and maintain strength and endurance, which greatly affects the ability to perform the tasks of daily living without undue physical stress and fatigue. Examples of tasks of daily living include home maintenance and household activities such as sweeping, gardening, and raking.
Muscular strength and muscular endurance directly impact on activities of daily living (ADLs) because daily living activity requires a given percentage of one's muscular capacity to perform common tasks. The enhancement of muscular strength and endurance enables an individual to perform such tasks with less physiologic stress and aids in maintaining functional independence throughout the life span. Even the cardiovascular stress of lifting or holding a given weight (object) is proportional to the percentage of maximal strength involved. Improving muscular function through resistance training (weight training) may accrue health-related benefits. A reduction in the risk of osteoporosis, low back pain, hypertension, and diabetes are associated with resistance training. In addition, the benefits of increased muscular strength and endurance, bone density, enhanced strength of connective tissue, and the increase or maintenance of lean body weight also may occur. These adaptations are beneficial for all ages, including middle-aged and older adults, and, in particular, postmenopausal women who may experience a more rapid loss of bone mineral density.
The following resistance training guidelines are recommended:
- Choose a mode of exercise (free weights, bands, or machines) that is comfortable throughout the full pain free range of motion
- Perform a minimum of 8 to 10 separate exercises that train the major muscles of the hips, thighs, legs, back, chest, shoulders, arms, and abdomen. A primary goal of the program should be to develop total body strength and endurance in a relatively time-efficient manner. Total exercise training programs lasting longer than 1 hour per session are associated with higher dropout rates
- Perform one set of each exercise to the point of volitional fatigue for healthy individuals, while maintaining good form
- While the traditional recommendation of 8 to 12 repetitions is still appropriate, choose a range of repetitions between 3 and 20 (e.g., 3 to 5, 8 to 10, 12 to 15) that can be performed at a moderate repetition duration (~3 sec concentric, ~3 sec eccentric)
- Exercise each muscle group 2 to 3 nonconsecutive days per week and if possible, perform a different exercise for the muscle group every two to three sessions
- Adhere as closely as possible to the specific techniques for performing a given exercise
- Allow enough time between exercises to perform the next exercise in proper form
- For people with high cardiovascular risk or those with chronic disease (hypertension, diabetes) terminate each exercise as the concentric (lifting) portion of the exercise becomes difficult, while maintaining good form
- Perform both the lifting (concentric phase) and lowering (eccentric phase) portion of the resistance exercises in a controlled manner
- Maintain a normal breathing pattern; breath-holding can induce excessive increases in blood pressure
- If possible, exercise with a training partner who can provide feedback, assistance, and motivation