Muscle strength refers to the ability to produce force and is often measured using a 1-repetition maximum (1RM) test. Increases in maximum strength are best promoted by regularly lifting loads ≥ 80% of 1RM.
Muscle Strength falls under theMuscle Gain & Exercisecategory.
Last Updated: January 31 2023
Muscle strength refers to the ability to produce force against an external resistance. It is often divided into specific types of strength, such as lower body strength or upper body strength.
Strength is commonly assessed using dynamic resistance exercise, which includes concentric (muscle shortening) and eccentric (muscle lengthening) muscle actions. The most popular method is a 1-repetition maximum (1RM) test, which involves lifting as much weight as possible for one repetition using either free weights or an exercise machine. A higher-repetition maximum test (i.e., a 2–6 RM) may also be used to assess strength and estimate 1RM strength.
Another option is an isometric strength test, which involves producing a maximal force against an immovable resistance. Unlike dynamic resistance exercise, the muscle length does not change during an isometric muscle action. Strong correlations have been reported between maximum dynamic and isometric strength.
In accordance with the principle of specificity — which states that training adaptations are specific to the demands imposed on the body — heavy loads (≥ 80% of 1RM) are superior to lighter loads for increasing 1RM strength. Training to muscular failure (i.e., the point at which another concentric repetition cannot be completed with proper form) is not necessary to increase muscle strength. In fact, ending each set a few reps shy of failure appears to be superior to training to failure for maximizing gains in 1RM strength. Also, rest intervals between sets should be at least 3 minutes.
Supplements marketed to enhance muscle strength typically claim to do so through one of the following mechanisms or a combination of them: increasing muscle contractile efficiency (e.g., by improving calcium handling in the sarcoplasmic reticulum), delaying muscular fatigue, increasing the availability of fuel sources (e.g., carbohydrate), and/or stimulating muscle protein synthesis.
The most effective supplements for increasing muscle strength appear to be creatine, protein, and caffeine. Other supplements that have been studied for muscle strength include nitrate, citrulline malate, HMB, alpha-GPC, taurine, ashwagandha, and omega-3 fatty acids.
Nutrition plays an important role in increasing muscle strength through fueling exercise and promoting recovery and exercise-induced adaptations. These processes are mainly influenced by protein and carbohydrate intake. Evidence suggests that a total daily protein intake of about 1.6 grams per kilogram of body weight is ideal for supporting increases in strength.
Muscle glycogen is a primary fuel source during resistance exercise, and glycogen depletion is associated with muscle fatigue and impaired muscle contraction efficiency, so consuming at least 3–5 grams of carbohydrate per kilogram of body weight per day is recommended to maximize strength gains.
With that said, many studies have not found differences in strength gains between higher- and lower-carbohydrate diets, particularly when the resistance exercise routine includes low volumes (< 10 sets per workout), high loads (≥ 80% of 1-repetition maximum), and long rest periods (≥ 3 minutes of rest between sets). However, there is a lack of evidence demonstrating benefits of lower-carbohydrate diets for muscle strength.
Differences in muscle strength between individuals seem to be mostly explained by differences in muscle mass, which is supported by the mechanistic rationale that a larger muscle has greater force-generating capacity. Other contributors to muscle strength include neural factors, such as the threshold at which motor units are recruited and the motor unit discharge rate, and genetics. Additionally, simply practicing the test used to examine strength (e.g., a back squat 1-repetition maximum) can promote increases in strength.