According to information, these vegetables help you to improve muscle mass:

Spinach: Spinach is a significant source of glutamine. It is one of the 20 amino acids that are involved in the composition of proteins. Therefore, it plays a very important role in the development of lean muscle mass. Also, it contains a component called coenzyme Q10. It is the same to an antioxidant, and it helps strengthen muscles. Spinach is a great source of magnesium. Magnesium is important for the proper functioning of energy metabolism, or making energy from nutrients. Also, magnesium is needed for the maintenance of muscle and nerve function. Lastly, spinach is rich in arginine, which is an amino acid that helps in stimulating the pituitary gland. Therefore, it helps stimulate the production of human growth hormones.

Sweet Potatoes: Sweet potatoes are not only delicious, but they also provide a various nutrition benefits to help enhance performance and fuel workouts. Their high fiber content helps in maintaining blood sugar levels, thereby, preventing fatigue throughout exercise. Also, sweet potatoes are a great source of beta-carotene, which is a natural pigment that converts to Vitamin A, a key vitamin for healthy and clear vision.

Barley or Wheat Grass: These plants are rich in vital minerals such as magnesium, calcium, and iron. Also, they contain carotenoids that act as antioxidants, and help tissue cells remain strong and healthy. You can easily add these 2 to any of your juices.

Bell Peppers: Whether you are into red, green, orange or yellow bell peppers, each contain nearly 2 grams of protein per a single ½-cup serving. Also, these colorful vegetables are great way to keep off those pesky colds as they are loaded with the immunity-boosting Vitamin C.

Beets: Beets are rich in magnesium, potassium, fiber, and various vitamins. Also, beets add the extra kick you need during aerobic training and weight lifting, due to its sugar content. Beetroot juice, in particular, is clinically proven to help in boosting stamina by allowing users to exercise for at least 16% longer. Also, beetroot juice reduces oxygen uptake “to an extent that cannot be achieved by any other known means, including training,” according to one scientist. A research team came to this conclusion by conducting a clinical study involving 12 men. Before they were place under a series of cycling tests, each man received about 140 ml organic beetroot juice or a placebo for 6 days. Power output and time-trial performance improved in athletes who consumed beets.

Parsley: Parsley stands out among the other healthy vegetables as an important source of nutrients. It contains various fundamental nutrients, including a vital amino acid known as lysine. This helps the regeneration and growth of connective tissues of tendons and cartilage. You can eat raw parsley in smoothies and salads combined with any other vegetables or fruits. Also, you can add it to any snack or meal.

Watercress: According to a 2014 CDC study, watercress contains the highest nutrient density score among 47 fruits and vegetables included in the study. This peppery green contains approximately 2 grams of protein, while only has 8 calories in 2 cups.  Watercress is a perfect addition to smoothies, packing a high dose of nutrients including iron and calcium.