) or faster (quality)? Luckily, bigger brains than mine have grappled with this question.Researchers Weigh InA study at the University of Northern lowa examined the quantity part of this dilemma. In the study, 51 university-aged men and women volunteered

to regular training and follow it with a taper that cuts mileage but maintains intensity work. It's a well-tested approach. Multiple studies confirm the basic concept of overload and adaptation; that is, vigorous training makes us stronger. In one study

SundayAM: 4 miles (easy)   PM: RestEd Eyestone is an exercise physiologist and two-time Olympic marathon runner

.The ResultsThe average runner in the study was able to run 19 fast fartleks at vVO2max pace before exhaustion. That’s nearly 10 minutes of very hard running. But these runners received an additional boost because they remained at their VO2max during part

, sugar can definitely have a positive impact on your performance. During a 5K or 10K, you’ll do fine without the sugar since you’ll probably be exercising for less than an hour. Studies show that during these shorter events, sugar offers little benefit

muscle contractions. As a result, according to a study at Ball State University in the USA, you'll run slower because your muscles will work less efficiently (which also makes them more prone to injury). The two lessons to be learnt here? Don't expect