Do a short but intense sprint interval program to build muscle and lose fat. Research shows that using a decreasing distance protocol—400, 300, 200, 100 meters—will produce a significant hormone response for optimal conditioning and body composition benefits.
Instead of doing the same sprint intervals for 20 to 25 minutes, mix up your training with advice from a recent study that shows that a few all-out sprints is all you need to experience adaptations.
This study compared the effect of doing four sprints in increasing distance order (100, 200, 300, 400 meters) or the reverse order on hormone response in elite power athletes. Rest intervals were a total of 9 minutes in both protocols with 4 minutes rest following the 400, 3 minutes rest following the 300, and 2 minutes rest following the 200.
Results showed that the decreasing order produced the following results and the athletes rated the workout as easier:
* Greater increase in growth hormone (GH) and blood lactate, indicating this protocol was more metabolically taxing and could lead to fat loss over time.
* A significant testosterone response, suggesting the protocol was effective for muscle building.
* A greater insulin-like growth factor-1 (IGF-1) response—a hormone that further enhances muscle adaptations—which is important because a previous study using longer intervals of 250 meters, but lower intensity didn’t elevate IGF-1.
* Greater stimulation of the GH-IGF-1 axis, highlighting that more time spent training anaerobically will produce a greater metabolic effect and more body fat loss.
Perhaps most interesting, although the decreasing distance protocol produced greater physiological overload, the athletes found it easier—they rated it 11 on an RPE scale compared to 13 for the increasing distance order. The athletes reported that having to increase the running distance so that the hardest sprints of 300 and 400 meters were at the end of the workout was very difficult to tolerate.
This is important since the primary drawback to sprint training is the mental challenge of pushing through physical pain. The take away is that doing a descending sprint protocol provides you a big bang for your buck AND it won’t feel as hard: Training smart yields better results than just training hard.