If running knocks the wind out of you, don't give up. You can increase your stamina, build your speed and pick up the pace by combining high-intensity interval training and endurance training. Before you hit the road, invest in a supportive pair of running shoes that provide ample shock absorption, then it's off to the races.
Training to the Max
Aerobic stamina is measured as your VO2 max, which is the maximal amount of oxygen you are able to use during vigorous exercise. VO2 max is determined by the efficiency of your cardiovascular system in delivering oxygen to your muscles, and by the capacity of your individual muscle cells to use oxygen to make ATP, the fundamental unit of energy that makes your muscles contract. Both your cardiovascular function and your cellular capacity are enhanced through training.
Endurance Goes the Distance
Endurance training, also called continuous training, involves sustained rhythmic large muscle contractions performed over an extended duration of time at a consistent intensity. Running is typically performed at continuous intensities, ranging from 35 to 65 percent of your estimated maximal heart rate. According to exercise scientist Len Kravitz, PhD, endurance training improves your cardiovascular function in several ways, including increased heart muscle size and ventricular wall thickness, making your heart a stronger pump; increased stroke volume, which is the amount of oxygenated blood ejected with each beat by your left ventricle; and increased chamber volume and dilation of the left ventricle, which means more blood is available per stroke. Extending the duration of your runs will increase your cardiovascular endurance, or stamina.
Intervals Up the Ante
Interval training consists of bursts of maximal intensity activity interspersed between "rest" intervals of continuous exercise. A 2007 Norwegian study of healthy young men published in "Medicine and Science in Sports and Exercise" compared physiological adaptations from continuous training to adaptations from interval training. They found that interval training had a more profound effect on improved VO2 max than continuous training. According to Kravitz, interval training can achieve similar and sometimes superior adaptations to endurance training in a shorter period of time. Adaptations from interval training include increased mitochondrial density in your muscle cells where aerobic energy is produced, increased fat metabolism, sparing of glucose and improved type l muscle fiber function.
Mix It to Max It
There are many ways to approach interval training. The Norwegian study set up two interval-training groups. One group ran all-out for 15 seconds, then ran at a "rest" pace for 15 seconds, repeating for 47 cycles. The other group performed four cycles alternating all-out effort for four minutes, with three-minute rest intervals. Each group averaged about 5.9 kilometers per training session, and did three sessions per week for eight weeks. Both groups saw significant improvements in VO2 max, with the group running longer intervals showing the greatest improvement. To develop your own interval program, begin with longer rest cycles and shorter high-intensity cycles. For instance, try two minutes of moderate-intensity running at your preferred pace, then sprint all-out for 30 seconds. As your stamina improves, lengthen your sprint intervals and shorten your rest intervals. To improve your stamina and go the distance, try alternating interval-training sessions with continuous endurance training.