The UK government recommendation on "minimum exercise levels" is 30 minutes five times per week, doing any form of exercise, for adults. (Children are expected to do higher levels).
But your question on "improving" health depends hugely on what the persons' current fitness level is, which is why it is not possible to give a general guideline on that basis. Similarly, "maintaining" the fitness of a person who is already extraordinarily fit will require far greater levels of activity than maintaining a person who is very unfit.
No
The top rated exercises for health include a combination of cardiovascular activity and strength training. Examples of cardiovascular activity including walking, jogging, or biking, while examples of strength training include weight lifting and resistance training.
The type of resistance training that involves muscles to move against resistance through an entire range of motion is called Isokinetic exercise. Here's the definition from the Glencoe Health Book: Isokinetic exercise- activity that involves resistance through an entire range of motion. I hope that helped you! :)
Resistance training
Stretching is not closely related to resistance training.
Resistance training is a kind of strength training in which each effort is performed against an opposing force generated by resistance. Resistance exercises develop the strength and size of skeletal muscles. Resistance training can improve overall health and well-being.
Stretching is not closely related to resistance training.
Generally, you can maintain a six-pack by doing the same thing you did to get the six-pack in the first place. Abdominal muscles are often the first ones obscured by adipose tissue, so it's important to maintain caloric intake relative to your activity level. In order to maintain the definition (the 'cut') of your abs, you should apply resistance training to them a could times per week (crunches are sufficient if you do not have the time or access to equipment to perform resisted crunches).
constant resistance variable resistance and accomodating resistance
If it is a true or false question your answer is: False. :)
strenghth
Muscular training