If the purpose of exercise is to gain muscle, do 5-8 groups of 6- 12 movements every day, not too fast, and the interval between each group is 2-3 minutes. The load is too large or too small, and the intermittent time is too long or too short, the effect will be bad.

The purpose of exercise is to reduce fat. It is suggested that each group should practice more than 15-25 times, and the interval between each group should be controlled at 1-2 minutes.

Dumbbell is a simple instrument to strengthen muscle strength training. Its main material is cast iron, and some are covered with rubber.

Used for muscle strength training and muscle compound action training. Patients with low muscle strength due to sports paralysis, pain, long-term inactivity, etc. Holding dumbbells, you can use the weight of dumbbells to actively exercise against resistance and train muscle strength.

Dumbbells can train a single muscle; If you increase your weight, you need the coordination of multiple muscles, and it can also be used as a kind of muscle compound action training.

Auxiliary equipment for weightlifting and fitness. There are two kinds of fixed weight and adjustable weight. ① Dumbbell with fixed weight. Cast with pig iron, with iron bars in the middle and solid balls at both ends. ② Adjustable dumbbells. Similar to a reduced barbell, round iron pieces with different weights are placed at both ends of a short iron bar about 40 ~ 45 cm long, which can increase or decrease the weight during weightlifting or fitness exercises. Doing dumbbell exercises often can enhance the muscle strength of all parts of the body.

References:

Baidu encyclopedia-dumbbell