Muscular strength is defined as the force or tension a muscle or a muscle group can exert against a resistance in one maximal contraction (Fox and Matthews, 1981). It is one of the most recognisable components of fitness, yet it is often misunderstood or confused with other components such as anaerobic power, muscular power and local muscular endurance. Muscular strength is an integral part of all of these three components and is rarely used in isolation.
Muscular strength is important in many sports - for example, those in which we try to gain or maintain position against an opponent, or in which we aim to move an object, our body or some body part, forcefully.
Factors Affecting the Application of Strength
Age: Maximal strength for males and females is attained at 25 to 30 years of age and declines thereafter by about 1% per year.
Sex: There is no discernible difference between the sexes in performance on fitness tests - including strength tests - until puberty. After puberty an untrained female has approximately two-thirds of the strength of an untrained male. This is due to the fact that males have a greater muscle mass and therefore a greater cross-sectional area than females.
Cross-sectional (size): The greater the cross-sectional area of a muscle, the greater the strength (there is no difference between the sexes in this regard).
Muscle Shape and Location: The multipennate arrangement of muscle fibres (such as in the quadriceps) is shorter and stronger but slower than the fusiform arrangement (such as in the hamstrings), which is longer and weaker, but faster. Strength is specific to a muscle or group of muscles: you can have a strong quadriceps but weak hamstrings ( a common factor in torn hamstrings).
Muscle Fibre Type: All athletes have two types of muscle fibre. White, fast-twitch (FT) fibres produce more force than red, slow-twitch (ST) fibres, but fatigue more rapidly. Red, slow-twitch (ST) fibres are therefore preferentially recruited for low-intensity (submaximal), prolonged aerobic work such as endurance activities. As the intensity of the activity increases, more FT fibres are activated.
A muscle biopsy is the only way to establish accurately the percentage of each fibre type. It is possible to presume the predominance of one type or the other by observing an athlete's performance in speed or endurance events.
Number of Muscle Fibres Recruited: It is important to realise that not all muscle fibres contract every time there is a nerve signal to do so. The number of fibres recruited (to contract) is governed by the strength of the nerve impulses emanating from the brain. The stronger the nerve impulses, the more motor units (the nerve cell and the muscle fibres connected to it) are activated, and therefore the more muscles fibres will contract. For a task requiring a minimal application of strength (for example lifting a glass), only a moderate number of muscle fibres will be activated. The most forceful contraction (that is, greatest application of strength) will occur when the maximum number of muscle fibres, of either fast-twitch or slow-twitch, are activated in a muscle - for example, when lifting a maximal weight.
Joint Angle and Muscle Strength: The force a muscle can generate is related to the length of the muscle and the angle of the limb relative to the joint. A muscle is potentially able to exert greatest force when stretched just past its resisting length (which could be compared with the stretching of an elastic band). This is the point at which the maximum number of acting and myosin filaments are overlapping to form cross-bridges.
Since a joint's mechanical advantage is not at its greatest when the joint angle is greatest, maximal strength can actually be applied when the muscle has begun to shorten and the joint angle is around 120 degrees. The speed of movement of a weight therefore varies during an isotonic contraction due to the changing mechanical advantage of the angle of contraction. Since it is easier to lift a weight when the elbow is bent at 120 degrees than at 30 degrees, the weight moves faster or more easily at this point.
(Malpeli, Horton, Davey, Telford, 2006).
TESTING MUSCULAR STRENGTH
When testing muscular strength, it really depends on the athlete, the sport they're associated with and the muscles the predominantly use. Below are some of the typical strength tests which are performed and are useful for a variety of sports.
1 Repetition Maximum or 3 Repetition Maximum lifts: This can be applied to a range of exercises but predominantly it is used in the bench press/squat/dead-lifts/flat barbell back pull. The steps to performing these exercises properly are as follows:
What do you need?
Range of free weights (Barbells)
How do you do the tests?
Begin by lifting a weight that you believe is close to your maximum.
Each time you perform a successful lift, rest for 3-5 minutes, then increase the weight by 2 to 5 kg for the next lift.
Continue until the maximum lift is achieved.
What results you’ll get :Strength is typically measured as a ratio of strength over body weight. With appropriate training, you should be able to lift at least your own body weight. Anything above 1.5 times your body weight is considered excellent. Performed regularly, this will allow you to measure the progress and effectiveness of your strength training.
Chin-Up Test: For athletes, the chin up test gives a good measure of strength over body weight, a key component in many sports.
What is the point? The chin up test is an excellent way to measure strength for many athletes. While it primarily focuses on arm and shoulder muscular endurance, it requires excellent overall upper body strength to complete with any success. What do you need?