Running and strength: economy matters

 However, if you're like many runners, you're probably a little confused about what running economy actually is. Having good economy does not mean picking up bargain shoes at your local discount shop; it simply means using less oxygen as you run. That's a great idea, not because you might one day have to run inside a vacuum tube or on the surface of the moon, but because it means you're running at a smaller percentage of your V02max, your maximal rate of oxygen utilization. As your percent V02max drops, running at a particular speed feels easier to you, allowing you to run farther or faster without feeling unduly fatigued. In fact, improving your economy by a measly I per cent can shave at least 20 seconds from your 1 0-K time.

So how do you improve your economy? Hill workouts represent one proven method, and Jack- Daniels-style 'reps' on the track (400-metre intervals completed about four to five seconds per 400 faster than your current 5-K pace, with several-minute recoveries) seem to work pretty well. And now there's another excellent way to bolster economy: recent research indicates that an effective strength-training programme can enhance your economy by up to 4-5 per cent, enough to trim over a minute from your 1 0-K clocking.

In the new research, which was carried out at the University of New Hampshire, six experienced female distance runners added upper- and lower-body strength workouts to their regular running training during a 10- week training period, while six other female runners shunned resistance training and continued their usual running programmes for 10 weeks. The women, who ran four to five days a week for a total of 20-30 weekly miles, were in 38:30 to 45:0010-K shape. None of the athletes had engaged in strength training during the three-month period which preceded the study.

The strength-trained group carried out resistance training on Monday, Wednesday, and Friday each week. There were two different strength sessions. 'Strength workout A' consisted of parallel squats*, knee flexions, straight-leg heel raises, seated presses*, rear-lat pulldowns, hammer curls*, and weighted sit-ups*. 'Strength workout B' was composed of lunges*, knee extensions, bent-leg heel raises*, bench presses*, seated rows, front-lat pulldowns, and abdominal curls (exercises with an asterisk were performed with free weights). The strength-trained group conducted workout A on Monday, workout B on Wednesday, workout A on Friday, workout B on the following Monday, and so on during the 10-week period, alternating session A with session B throughout the programme. When running and resistance training took place on the same day, the running workouts and strength-building sessions were always separated by at least five hours of rest.

The actual number of sets and reps in the strength workouts were as follows:

Workout A
Weighted sit-ups: 2 X 15 (2 X 15 means two sets of 15 reps)

Straight-leg heel raises: 2 X 12 Knee flexions: 3 X 8
Rear-lat pulldowns: 3 X 8 Parallel squats: 3 X 6 Seated presses: 3 X 6 Hammer curls: 3 X 6
Workout B Lunges: 3 X 6 Bench presses: 3 X 6 Knee extensions: 3 X 8 Seated rows: 3 X 8 Front-lat pulldowns: 3 X 8 Bent-leg heel raises: 2 X 20 Abdominal curls: 2 X as many as possible Two-minute rest intervals followed each set, and in all cases the resistance was adjusted so that complete fatigue was reached after the indicated number of reps (no further reps could be completed during a set). Most of the exercises are familiar ones; the only exception might be 'hammer curls,' which are just biceps curls carried out with the palms of the hands facing toward the body, instead of facing straight ahead.

What happened?
After 10 weeks, the strength-trained runners improved their upper-body strength by 24 per cent and raised their lower-body strength by 34 per cent, while the non- strength-trained athletes failed to boost muscle strength at all. In addition, there was a trend for exercise heart rate to diminish in the strength-trained group. Before strength training, the women ran with a heart rate of 187 beats per minute while cruising at 6:30 per mile pace; after strength training, their pulse rate registered 183 at the same running tempo. Likewise, heart rate at seven-minute tempo dropped from 181 to 177 beats per minute. Most significantly, running economy also improved in the strength-trained group, but didn't change at all in the runners who avoided strength training.

In fact, at the end of the study, it 'cost' the strength- trained runners about 4 per cent less oxygen to run at their original 10-K race pace of about 6:30 per mile. This means that after strength training the runners could complete their 10Ks much more easily, or, better yet, that they could run their 10K races at a pace of 6:17 per mile without experiencing any feelings of increased effort! That positive change would produce over an 80- second improvement in 10-K time. Indeed, those strength-trained runners who actually raced reported improvements at race distances from SK to the half marathon.

 The strength increases and economy enhancements in the strength-trained runners were not accompanied by upswings in body mass or body-circumference measurements. In other words, the strength-trained runners did not 'bulk up'. That's good, since runners don't ordinarily relish the idea of carrying around extra weight as they run.

How did it all work?
Why did the strength training improve economy? Several explanations are possible. First, the resistance training no doubt improved the strength of individual cells in the runners' leg muscles. With more strength per cell, fewer fibres needed to be activated during running, lowering the total oxygen demands of the leg muscles.

Second, as New Hampshire researcher Ron Johnston points out, 'Excessive, unnecessary body motions during running waste energy and use up oxygen. As the resistance-trained runners became stronger, their body parts probably became more stable during running. Since there was less unnecessary motion, the total oxygen demand decreased.'

A third possibility is that strength training improved the coordination of muscle activity by the athletes' nervous systems, allowing more propulsive, forward (and for each quantity of oxygen gobbled up by the muscles).

Whatever the mechanism, it's clear that strength training -- of the kind carried out by the New Hampshire runners or the type recommended by Walt Reynolds in his article in issue 54 of PEAK PERFORMANCE- - is likely to improve running economy, which will lead to more trouble-free workouts and better race performances.

It works for cyclists, too
What has other research said about strength training and endurance running? Several years ago, scientists at the University of Illinois at Chicago placed eight experienced runners on a very simple strength-training programme which included three strength workouts per week over a 10-week period. Only four actual strength exercises were utilized: parallel squats, knee extensions, knee flexions, and heel raises (all of which were also used in the more recent New Hampshire study). Resistance was set fairly high, so that only about five reps could be completed per set, and the number of sets of each exercise varied from three to five.

After 10 weeks, leg strength increased by about 30 per cent, without any increase in muscle bulk. In addition, endurance while pedalling a bicycle to exhaustion at a strenuous intensity of 88 per cent of maximal heart rate increased from 71 to 85 minutes, a 20-per cent upswing. Finally, endurance while running at fairly high speed (somewhere between one- and two- mile race pace) increased by about 13 per cent after the strength training. Overall, the study confirmed the idea that strength training could bolster both cycling and high-speed running endurance.

In a separate, often-mentioned study, E. J. Marcinik and colleagues at the University of Maryland asked 10 males to participate in strength training for 12 weeks, while eight males served as a control group, taking part in no resistance training at all. The strength-trained group improved their endurance while riding on an exercise bicycle by 33 per cent and also boosted their cycling lactate thresholds by an average of 12 per cent, while the control group made no gains at all. This study is often cited as providing 'proof ' that strength training can enhance lactate threshold in experienced athletes, but in fact it does nothing of the kind, because all of the subjects were previously untrained. This means that any form of activity might have lifted threshold -- and that there's no real evidence that a real-live athlete would get a lactate-threshold uptick from strength training. In fact, in the New Hampshire research, although resistance training had a strong effect on economy, it had no impact on lactate threshold at all.

So what's the bottom line? Many runners just run when they train, avoiding resistance training like the plague. The most current research indicates that this is a bad idea, because strength training can ameliorate economy and trim time from race efforts. However, it's important to bear in mind that the runners who will benefit the most from strength training are the ones who haven't carried it out systematically in the past. Individuals who have been conducting strength training for at least a few months are likely to achieve smaller gains.

Owen Anderson