No matter what type of workout you're doing, whether it's a leisurely walk or a power cycling session, your environment can have a huge impact on your rate of exertion. The best way to measure your work rate during exercise is through your heart rate, and climbing a hill increases your heart rate much more than flat terrain by adding resistance to your workout.
Although age, genetic factors and temperature can all impact your heart rate, your rate of exertion is the key factor when it comes to your workout. When you add a hill into the equation, any workout you do requires much more effort because of the added resistance of gravity. Walking at 2 miles per hour at a 24-percent incline can increase your heart rate by 55 percent compared to walking on a flat surface. If you run uphill, the effect is compounded, meaning you can't sustain the exercise for very long.
Because incline training adds more resistance to your workout, it requires your muscles to contract more forcefully to propel you up the hill. According to Brian Mackenzie, a renowned track coach from the U.K., training at an incline recruits up to three times more muscle fibers than training on flat ground. What started out as a steady aerobic run on flat land turns into an anaerobic sprint when running uphill. More muscle contractions require more blood and oxygen, which increases your heart rate.
Although you won't be able to keep up a hill-climbing session as long as you could keep up a normal jog, you can still build muscular and cardiovascular endurance with hill training. Additionally, you'll also encourage muscle growth, elasticity, coordination and lactate tolerance the more you train. Since your heart has to work harder during hill-climbing sessions, it will grow stronger over time, increasing it's power and efficiency and lowering your resting heart rate.
The very attributes that make hill climbing such an effective method of training are also some of the same reasons many people find it so difficult. Walking at 3 mph at a 12-percent incline will produce the same heart rate as running twice that speed on a flat surface. Hill climbing is intense and should not be done on consecutive days to allow for proper rest and recovery.
Steven Kelliher is an experienced sports writer, technical writer, proofreader and editor based out of the Greater Boston Area. His main area of expertise is in combat sports, as he is a lifelong competitor and active voice in the industry. His interviews with some of the sport's biggest names have appeared on large industry sites such as ESPN.com, as well as his own personal blog.