Fatigue strength is often characterized as the amount of stress that can be applied before causing fatigue. In relation to personal fitness, it's best described as muscle fatigue, or the point at which the muscles are no longer able to exert enough force to complete a given task. Once you hit muscle fatigue, you need to use more effort than normal to achieve the same level of force.
Muscle Fatigue
As you engage in any type of physical activity, you tap into your energy reserves, which triggers the metabolism to produce more. During this process, your body creates a byproduct known as lactic acid, directly impacting the pH of the muscles. More acid in the muscles limits their ability to contract and thereby causes muscle fatigue, explains the International Sports Science Association.
Prevention
According to Harley Pasternak, physical trainer and author of the "5-Factor Diet," you can delay muscle fatigue by putting into place certain self-care measures. One of the more important is diet. Finding the right ratio of carbs to protein for your athletic pursuit is often beneficial. Endurance athletes can stave off fatigue with a higher ratio of carbohydrates to protein. Someone running a marathon might load up on carbs by increasing his carbohydrate intake to 60 percent of his diet. Sports athletes, on the other hand, can delay fatigue with an equal amount of carbs to protein. In this situation, your diet may include 40 percent carbohydrates and 40 percent protein.
Other Factors
In addition to diet, proper hydration can help in delaying fatigue. Pasternak recommends at least 80 to 96 oz. of water each day to keep your muscles from reaching fatigue too soon. You may also inhibit fatigue with supplements containing caffeine, ginkgo biloba, tyrosine, sodium carbonate or creatine monohydrate.
Recovery
Another importance facet to muscle fatigue is recovery. When training, it's best not to work the same muscle group two days in a row. In fact, the larger the muscle group, the more rest you tend to need between training sessions. If you're still sore, avoid working that muscle group for another day to prevent overtraining, which not only leads to muscle fatigue, but also can waylay muscle growth.
But resting enough days between workouts isn't always enough. You also need to pay attention to the time spent resting between sets during a workout. The larger the muscle group, the longer you should take between sets. The muscles in your legs or back may require 2 to 3 minutes between sets, where as the biceps or triceps only need upward of 60 seconds.
