According to a Harvard Medical School study, "The meta-analysis makes a strong case for walking. In all, walking reduced the risk of cardiovascular events by 31%, and it cut the risk of dying during the study period by 32%. These benefits were equally robust in men and women. Protection was evident even at distances of just 5½ miles per week and at a pace as casual as about 2 miles per hour." Though the study focused on walking, it emphasized the benefits of climbing stairs and moderate to strenuous exertion (which covers hiking).
According to a Korean study from 2008, for participants who walked a 40 minute brisk (3-4 mph) session and four 10 minute brisk sessions, "Blood pressure dropped by similar amounts after each type of exercise session. The top number in the blood pressure reading dropped about 5 points after the 40-minute walk and 3 points after the four 10-minute walks".
Moderate exercise can prevent, or help maintain, Type II diabetes.
For preventing diabetes, the NIH states, "Studies show that people at high risk for diabetes can prevent or delay the onset of the disease by losing 5 to 7 percent of their weight, if they are overweight—that's 10 to 14 pounds for a 200-pound person."
To take care of existing Type II diabetes, the NIH states, "Physical activity and keeping a healthy weight can help you take care of your diabetes and prevent diabetes problems. Physical activity helps your blood glucose,* also called blood sugar, stay in your target range."
According to an article on the Anxiety and Depression Association of America's (ADAA) website, exercise "has been shown to decrease overall levels of tension, elevate and stabilize mood, improve sleep, and improve self-esteem. About five minutes of aerobic exercise can begin to stimulate anti-anxiety effects."
The ADAA also states "According to some studies, regular exercise works as well as medication for some people to reduce symptoms of anxiety and depression, and the effects can be long lasting."
In the National Osteoporosis Foundation's webpage on exercise, they emphasize weight-bearing and muscle strengthening exercises. "There are two types of exercises that are important for building and maintaining bone density: weight-bearing and muscle-strengthening exercises."
According to the National Arthritis Foundation's website, hiking is a great exercise for people with arthritis. "What’s more, a regular walking routine compresses and releases the cartilage in your knees, helping circulate synovial fluid that brings oxygen and nourishes your joints and removes inflammatory waste products."
In an article on the Fitness Blender website, "Trekking up hills or mountainsides is hard work, and it engages multiple muscle groups in tandem, all while burning a serious number of calories and increasing your aerobic threshold."
Additionally, in an article on the Live Strong website, hiking "provides cardiovascular and pulmonary benefits, and works major muscle groups so that you improve your stamina, endurance, strength and muscle tone."
According to a Health.com article (interviewing Marie Dacey, EdD, assistant professor of psychology at the Massachusetts College of Pharmacy & Health Sciences and a certified personal trainer) about hiking, "The uneven surfaces and varying terrain you'll experience on the trails bring all kinds of challenges and rewards, including helping the body with balance, strength, and flexibility."