Manys runners loathe the idea of dropping mileage and replacing the "lost" miles with explosive strength training, but new research from Finland reveals that such a strategy can significantly improve maximal running speed and leg muscle power - workout any loss in maximal aerobic capacity. In the new investigation, experienced runners reduced weekly mileage by 20 percent and upgraded maximal running velocity by 3 percent. REPLACING MILES WITH EXPLOSIVE MOVES

What happens if you suddenly decided to chop 20 percent of your usual miles from your weekly log - and then replaced that lost mileage with explosive training which required a comparable amount of time? Many runners would suggest that such a move would deplete maximal aerobic capacity (VO2max), because of the lower overall volume of endurance training which would be conducted. Furthermore, many coaches and runners would say that the change would produce a drop in fitness and race performances, because of the necessarily abridged maximal aerobic capacity. Given such thinking, it is not at all surprising that so few runners carve away at their mileage and substitute explosive work for their endurance-type training.

However, there have been various hints in the scientific literature that such substitutions could produce surprising benefits. Some research, for example, has shown that "anaerobic work capacity" (the kind of thing which is fostered by explosive training) can have an important impact on endurance performance (1). In addition, Tim Noakes' now classic paper revealed that "neuromuscular characteristics" {basically, the ability of muscles to produce high amounts of force very quickly) could predict endurance-performance capability more successful than good-old VO2max (2). Producing force quickly is a key adaptation associates with explosive training. Thus, these inquires suggest that the traditional thinking about mileage and high-power work might be wrong.

Fortunately, the question of what really happens when endurance work is replaced by explosive training intrigued by Jussi Mikkola, Heikki Rusko, and their colleagues at the Research Institute for Olympic Sports in Jyvaskyla, Finland. Recently, Mikkola, Rusko, and their co-workers asked 13 well-trained young runners (nine males, four females) who were training about 8.8 hours per week to pare 1.7 hours from their weekly logs (leaving about 7.1 hours of endurance training) - and then to incorporate 1.7 hours of explosive training into their schedules each week for a period of eight weeks (thus maintaining the usual 8.8 total hours of effort). These runners were young (average age = 17.3 years) and fit (mean VO2max = 62.4 ml'kg-1 min-1). REPLACING MILES WITH EXPLOSIVE MOVES

The explosive training was carried out three times a week (which meant that each session lasted for about 34 minutes). The workouts consisted of high-speed sprint intervals ((5 to 10) X (30 to 150 meters)), jumping exercises with no additional resistance (alternate-leg jumps, and hurdle jumps), and "gym exercises" with fairly light resistance (half squats, knee extensions, knee flexions, calf raises, abdominal curls, and back extensions). For the gym exertions, two to three sets of six to 10 repetitions were utilized, and the underlying philosophy for all of the explosive movements was to use very high action velocities.

And, yes, this was a Heikki Rusko study, so there was a very nice control group - 12 individuals in all (nine men and three women) who were also young (17.3 years) and fit (VO2max = 61.8 ml'kg-1min-1). These controls pretty much stayed away from the explosive training during the eight-week period, instead focusing on 8.5 hours per week of endurnce training.

Muscle strength, jumping ability, and 30-meter running speed were measured in both the explosive and control groups at the beginning and end og the eight week period. And - since this was a Rusko study - all runners performed a maximal anaerobic running test, or MART (Rusko is one of the primary developers of the MART). A MART can be completed on a treadmill (3 & 4), but in this research the testing took place on an indoor track. Basically, a MART is a series of 150-meter runs, with 100-second recoveries between runs and a five meter flying start before each 150-meter effort. The velocities of the 150-meter runs are tightly controlled. In this research, the first was carried out at 39.4 meters per second (101.5 seconds per 400 meters) for females and 4.75 meters per second (84 seconds per 400 meters) for males. After that, the velocity was increased by .41 meters per second for each consecutive 150-meter effort. At the well equipped Rusko lab in Jyvaskyla, the runners were guided into running at the correct velocity by a "light rabbit" (a moving light which moved around the track at the required speed). In a MART, the last 150-meter run is completed at maximal effort, and ordinarily about nine to 10n 150-meter surges are completed per test. Fairly fast speeds are attained during the test. For example, a male runner who manages to perform 10 150-meter runs would complete the last effort at no less than 8.44 meters per second (47 seconds per 400 meters, if he could "hold on" that long).

Over the course of eight weeks, the explosive training paid major dividends. The maximal speed in the MART (the velocity attained for the last 150-meter sprint) increased by 3 percent in the explosively trained runners - but failed to budge at all in the regular, endurance-trained subjects. Furthermore, 30-meter speed (the top velocity achieved in a 30-meter sprint which was preceded by a 20-meter flying start) advanced by 1.1 percent for the explosive runners - but was stagnant for control individuals. REPLACING MILES WITH EXPLOSIVE MOVES

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WHY THE FASTEST RUNNERS OFTEN GET STIFFED

TRADITIONALLY, ENDURANCE ATHLETES have not placed a major emphasis
on explosive strength training. The rationale for this avoidance of explosive
work has been that such training might carry a high risk of injury, and that
high-speed, “anaerobic” movements have little relevance for the “aerobic”
athlete whose success depends on steady endurance. AURORA

However, scientific evidence continues to show that such thinking is
wrong: Th e research reveals that explosive training helps endurance athletes
in a number of key ways. For example, in a brand-new study carried out by
Rob Spurrs and co-investigators at the University of Technology in Sydney,
Australia, explosive training improved performance times for 3-K runners by
almost 3%.

The explosive workouts designed by Spurrs and colleagues were simple to
carry out, and the athletes performed them only two times a week for three
weeks and then three times a week for three weeks (1). Just eight diff erent, easy to-
learn exercises were utilized (squat jumps, split-scissor jumps, double-leg
bounds, alternate-leg bounds, single-leg forward hops, depth jumps, double-leg
hurdle jumps, and single-leg hurdle hops), and the Australian athletes usually
performed no more than four of these exercises per workout (generally using
two to three sets of 10 to 15 reps per exercise). Before the six-week study began,
the athletes were running about 35 to 50 miles per week.

Here are descriptions of the less-familiar exercises: To carry out split-scissor
jumps, an athlete would start with one leg out in front of the other. If the left
leg was in front of the right leg, the distance between the back of the left heel
and the toes of the right foot would be approximately one shoe length. The
athlete would then bend at the hips, knees, and ankles and then attempt to
jump as high as possible. While airborne, his legs would cross so that the right
leg would be in front of the left upon landing. This action would continue for
the duration of the set, creating a scissor-like action throughout the drill (and
a split stance with each landing). Subjects were given instructions to jump as
high as they possibly could – but with minimal ground-contact time during
each landing stage of the movement. Thus, the runners had to compromise the
vertical height of their jumping somewhat in order to decrease the duration of
ground contact. No restrictions were given to the athletes regarding the depth
of knee or hip flexion, but the runners were asked to maintain upright posture
with their torsos. FASTEST RUNNERS 

To perform depth jumps, an athlete stood on a box with a height of 40
centimeters (15.75 inches). Then, the athlete was instructed to simply step off
the box, as though he were taking a routine step on normal ground. During
the 40-centimeter, downward “flight,” the athlete had to quickly bring the
non-stepping foot into position so that the landing was made on both feet
simultaneously. Upon landing, the athlete attempted to minimize ground contact
time and yet jump as high as possible.

After coming back to terra firma following the explosive jump, the athlete simply stepped back onto the box andrepeated the overall action for the prescribed number of times. When steppingoff the box, an athlete was not permitted to “step down” from the box, as he
would when debarking from a train or stepping off a kitchen stool. Rather, the
action was supposed to be a step forward from the box, as though another box
of the same height was ready to meet the stepping foot and then a quick 40-
centimeter plunge.

To carry out double-leg hurdle hops, an athlete jumped over 10 hurdles,
positioned 115 centimeters (45 inches) apart, with a height of 70 centimeters
(27.6 inches). Th e athlete jumped over each hurdle, landing and taking off on
two legs, until all 10 hurdles had been cleared (movement was continuous).
Again, the athlete was instructed to minimize ground-contact time.

While doing single-leg hurdle hops on one leg at a time, an athlete also
jumped over 10 hurdles in continuous fashion, but this time the hurdles were
only 42 centimeters (16.5 inches) high and were placed 160 centimeters (63
inches) apart. Minimal ground-contact time was again the order of the day.
The pervading theme for all of the exercises used in the investigation was
to get as high as possible with the least amount of ground-contact time. For the
double- and alternate-leg bounds and also for the single-leg forward hop (i. e.,
the drills which focused more intently on horizontal movements), this theme
was also applied – but with the added instruction that the greatest-possible
horizontal distance should be covered with the most-abbreviated-possible
ground contact. FASTEST RUNNERS

After just six weeks of the power sessions (15 workouts in all), the
explosively trained Australian runners improved 3-K running time by
16 seconds, while control competitors (who ran in a similar way but did no
explosive work) failed to upgrade 3-K running ability at all.

Interestingly enough, the explosive training also improved the efficiency
of the Australian harriers, enhancing running economy (the oxygen cost of
running at a particular speed) by from 4 to 7% at three diff erent velocities. Th e
training improved the rate of force production in the athletes’ calf muscles and
also made the runners’ legs stiff er by 11 to 15%.

Stiffer? Yes, I know that sounds strange. After all, isn’t stiff ness supposed
to be a bad thing for endurance runners, something you attempt to avoid by
faithfully carrying out stretching activities?

Well, stiffness can be a negative, if it is excessive, but in this case the
increased stiffness helped the runners react with the ground more explosively
with each footstrike. Their legs were less compliant, and as a result they probably
spent less time in the stance phase of the gait cycle without sacrificing an inch
of stride length; in fact, it is likely that stride length was greater than before the
explosive training began. FASTEST RUNNERS

Overall, explosive training improves endurance-runners’ performances by
expanding forward propulsion with each foot strike at an energy cost which is
less than before and with a total footstrike time which is less than before the
training began. Explosive training makes runners both more economical and
faster.

What about injury? The power-trained Aussies suffered from nothing more
than a little soreness after their first few explosive workouts; after that, everything
proceeded smoothly. In fact, carefully conducted explosive training should be
anti-injury, since it enhances muscles’ abilities to withstand high, sudden force
loads.

Overall, it is clear that explosive work is an essential part of an endurance athlete’s
training. Endurance athletes who avoid explosive sessions have a
difficult time achieving their highest-possible levels of performance.

Reference
(1) “The Effect of Plyometric Training on Distance Running Performance,”
European Journal of Applied Physiology, Vol. 89, pp. 1-7, 2003