Developing research has demonstrated that many of the benefits of exercise are mediated through the role of skeletal muscle as an endocrine organ. That is, contracting muscles release multiple substances known as myokines, which promote the growth of new tissue, tissue repair, and various anti-inflammatory functions, which in turn reduce the risk of developing various inflammatory diseases.
The Physical Activity Guidelines for Americans were created by the Office of Disease Prevention and Health Promotion. This publication recommends that all adults should avoid inactivity to promote good health mentally and physically. For substantial health benefits, adults should participate in at least 150 minutes a week of moderate-intensity, or 75 minutes a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity. Aerobic activity should be performed in episodes of at least 10 minutes, and preferably, it should be spread throughout the week.
To exercise, work, do daily chores and play sports, you’ll need varying levels of cardiorespiratory capacity and stamina, muscle strength and endurance, footwork skills and speed. Training for one type of fitness often requires different types of exercises than training for another type of fitness. For example, strength training uses heavy weights and slower muscle movements than sprint training, which is performed with little resistance and high-speed muscle movements. These different types of fitness workouts recruit different muscle fibers and burn different amounts of fat and glycogen. It's best to focus on strength and endurance exercise during a sport off-season, and work on speed and recovery during the preseason and in season.
^ Osawa Y, Azuma K, Tabata S, Katsukawa F, Ishida H, Oguma Y, Kawai T, Itoh H, Okuda S, Matsumoto H (2014). "Effects of 16-week high-intensity interval training using upper and lower body ergometers on aerobic fitness and morphological changes in healthy men: a preliminary study". Open Access Journal of Sports Medicine. 5: 257–65. doi:10.2147/OAJSM.S68932. PMC 4226445. PMID 25395872.
There are different categories or types of physical fitness training. Each corresponds to a defined purpose or fitness goal such as the development and improvement of one or more of the five dimensions of physical fitness, or for participation in a particular type of sports and rehabilitation through physical training, among others. Note that the different types of training also correspond to the different categories or types of exercises.
Possibly one of the most important parts of fitness training is flexibility and mobility. Flexibility is the ability of your muscles to stretch, and mobility is being able to move your joints and tissues through their full range of motion. Both are important to athletic performance and for avoiding injury. Muscles and joints that are flexible and mobile — as well as strong — are much less susceptible to sprains and other injuries.
New (July 2011) guidelines in the United Kingdom include the following points: The intensity at which we exercise is key, and light activity such as strolling and housework is unlikely to have much positive impact on the health of most people. For aerobic exercise to be beneficial it must raise your heartbeat and make you sweat. The more exercise you do, the better. Everyone should do a minimum of 150 minutes a week of moderate-intensity aerobic exercise but that really is the minimum for health benefits. If you can go beyond 150 minutes, you’ll gain even more health benefits. Sedentary time (time spent sitting down to watch TV, use a computer, read or listen to music) is bad for your health, even for those who are achieving 150 minutes of exercise a week. These guidelines, are now much more in line with those used in the US, also include recommendations for muscle-building and bone strengthening activities such as lifting weights and yoga.