Posted: September 9, 2005

Science of Sport: Can Going To The Ball Help You Run Faster?

By Owen Anderson, Ph. D. (Copyright © 2004-2005)

The idea that improved core stability leads to better running economy appears to be one of those “slam-dunk” propositions. After all, upgraded strength in the abdominal and low-back muscles should prevent unnecessary movements of the trunk during running, lowering the energy cost of moving along at one’s chosen pace (overall cost is reduced because the muscular activity needed to correct improper trunk motion becomes minimal). A solid core also provides an unshakable foundation for the legs as they exert force upon the ground; this should lead to more distance covered per step and per unit of muscular force, enhancing efficiency. Finally, a Gibraltar-like core reduces the likelihood of excessive arm swing during running (1). Extra arm swing is often a natural attempt to compensate for weak core muscles; when the core lets the trunk rotate too much with each step, the arms try to compensate by “overswinging” to fight off the trunk’s wild gyrations. Get the core in shape, and the arms settle down, too.

Athletes use a variety of “ab” and low-back exertions to get their mid-sections in shape, but they are seldom sure that their tedious core efforts are actually improving their stability during their sporting movements, which is what really matters. Published research in this area is light, to say the least, but there has been an interesting recent development: Various scientific investigations have suggested that training with a Swiss ball can boost core strength in a functional way. For example, a study completed with Rugby Union players determined that Swiss-ball work decreased the risk of low-back injury (2). A separate piece of research carried out with collegiate swimmers found that Swiss-ball training upgraded core stability (3).

There is also an interesting theoretical underpinning for Swiss-ball exertions, as opposed to tried-and-true exercises such as ab crunches and low-back extensions. As any Swiss-ball exerciser can verify, a Swiss ball provides a very unstable surface upon which to complete one’s exertions. Such instability is thought to enhance “neuromuscular pathways” (i. e., it may force the nervous system to learn to control key movements more effectively, by using the most-appropriate collections of muscle cells and by “firing up” those muscle-fiber assemblages at exactly the right time – all as part of an effort to counteract the instability). This enhancement may dramatically improve proprioception and balance and thus promote better efficiency of effort (4). Some researchers have suggested that Swiss-ball work should optimize the coordination of synergistic and stabilizer muscles (the sinews which help the primary force-producer(s) during a movement and which prevent unnecessary motions) (5). This contention certainly makes sense, because stabilizer muscles would be under increased pressure to produce force to counteract the Swiss-ball’s tendency to roll out from under a body part during exercise.

In fact, it is clear that movements carried out with a Swiss ball can produce greater activation of muscles during training, compared with the same motions performed on a stable surface. In one key study, abdominal muscles (including the rectus abdominis and external-oblique muscles) were activated to a significantly greater degree during abdominal curl-ups on a Swiss ball, compared with non-Swiss-ball curl-ups (6). Such heightened activation should – over the long term – lead to greater gains in strength in the involved muscles.

All of this sounds very nice, of course, but the truth is that there has been a relative paucity of solid evidence to back up the idea that Swiss-ball training can strengthen and economize sports-specific movements. Until recently, no study has ever taken a close look at whether Swiss-ball training can upgrade running economy, for example. Correcting that situation, researchers from Central Queensland University in Australia and Ball State University in the United States have just completed an investigation of the effects of Swiss-ball training on core stability and running economy in 18 male athletes (7). The subjects were young (average age was 15.5 years), had a relatively decent VO2max (55 ml.kg-1.min-1), and were fairly lean (BMI = 21 kg/m2); none had engaged in Swiss-ball drills prior to the beginning of the investigation.

Before any training was carried out, all of the athletes were given a Sahrmann core-stability test. This exam involves lying on one’s back, with the inflatable pad of a Stabilizer Pressure Biofeedback Unit tucked into the natural lordotic (low-back) curve of the spine; the pad is inflated to a pressure of 40 mm Hg. “Abdominal pre-setting” is then performed, with an athlete activating the abdominal muscles so as to brace the trunk in an isometric fashion, with no overall movement being produced. Once the pre-setting is accomplished, the athlete slowly raises one leg to achieve 100 degrees of hip flexion, with the knee of the raised leg flexed comfortably. The opposite leg must then be brought to the same position in identical fashion, with an alteration of no more than 10 mm Hg in pressure in the Biofeedback Unit (increases in pressure, for example, would indicate a major change in body position and thus a lack of stability). The both-legs-up scenario is then considered the starting position for the remainder of the test.

From the starting position, an athlete lowers one leg so that the heel contacts the ground. The lowered leg is then fully extended at the knee – and returned to the starting position. One leg is then lowered so that its heel is approximately five inches off the ground, followed by leg straightening and a return to the starting point. To make matters even tougher, both legs are then simultaneously lowered so that the heels touch the ground, followed by full extension at the knees and then the lifting of the legs back to the starting point. Both legs are then taken down to a position five inches above the floor, followed by extension and lifting. Throughout all of this, a change of no more than 10 mm of pressure is permitted in the Biofeedback Unit. It is a rugged test!

The athletes also completed an interesting Swiss-ball-prone-stabilization-core-stability (SBPSCS) test which involved getting into a challenging push-up position with the elbows locked and the toes perched on the apex of a mediBall Pro Swiss Ball™. Ball size was selected so that each athlete’s body was parallel with the ground at the beginning of the exam. The basic position was held for as long as possible, and the time to failure was recorded. VO2max, vVO2max, and running economy were also determined on a laboratory treadmill.

Eight of the subjects then embarked on six weeks of Swiss-ball training, while 10 athletes served as controls. The Swiss-ball efforts were performed twice a week, and each Swiss workout took about 25 minutes. Six key Swiss-ball exercises were utilized – lunges, supine lateral rolls, alternating supermen, forward rolls on knees, supine two-leg bridges, and supine Russian twists, with the number of sets of each exercise gradually progressing from two to three and the number of reps per set holding steady at about eight to 10. Otherwise, all 18 athletes carried out their usual skills training and run-based conditioning.

The six weeks of Swiss-ball exertions improved core stability and strength – when those variables were measured during the Sahrmann and SBPSCS tests. After six weeks, Sahrmann scores for the Swiss-trained athletes were higher, compared with those for the control subjects. In addition, time to failure during the SBPSCS expanded by about 40 percent for the Swiss-ball devotees but was static for the regular trainers. It was clear that the Swiss-ball drills had upgraded coordination, strength, and fatigue-resistance during the Sahrmann activities and in the static body position required for the SBPSCS exam.

Unfortunately, the results were much less impressive for the running component of the investigation. As you might expect, the Swiss-ball training had no effect at all on VO2max. The hope, of course, was that Swiss movements would enhance running economy (by producing greater strength in the core and greater whole-body stability) and thus might even aggrandize vVO2max, which is strongly influenced by running economy. Sadly, the data revealed that Swiss-ball workouts had no impact at all on these key variables. In addition, running posture was also unaffected by the Swiss training; there were no observable changes in running form (the scientists carefully measured trunk position during running before and after the Swiss-ball program was completed). The hypothesis had been that the Swiss-ball efforts might help the runners move along in a more upright manner, without excessive forward lean.

So what was the problem? A key difficulty, of course, may have been that the Swiss-ball exercises utilized during the training had little resemblance to the movements involved in real-live running. Strength training fortifies movements, not muscles, and if strength training is not specific to the movements involved in a particular sport, one should not expect to be stronger in that sport, even when considerable “progress” has been made with the training movements (with greater resistances, higher numbers of sets and reps, increased instability, etc.). The lack of effect of Swiss-ball training on running parallels the study (mentioned earlier in this story) carried out with college-age swimmers, in which ball exercises upgraded core stability but led to no improvements at all in swimming performances (3).

That’s not to say that Swiss-ball training is completely worthless. For one thing, the Central-Queensland-Ball-State study only lasted six weeks; perhaps more time is needed for ball training to work its magic, or perhaps the exercises themselves need to be made more challenging. In addition, Swiss-ball efforts do produce some general strength in the core (as shown by the Sahrmann and SBPSCS tests), and it is possible that this general strength could be converted to running-specific strength with the follow-up (or simultaneous) use of more running-specific core exercises such as arm swings with dumbbells (carried out in a one-leg position, with the arms moving back and forth as they would during the gait cycle and dumbbells held in each hand).

At present, however, we have to conclude that there is no evidence at all that Swiss-ball training can improve running economy, a key predictor of running performances. That does not leave you high-and-dry when it comes to economy training, however, since research strongly suggests that strength training (especially involving movements which resemble running motions) and hill training are strong economy enhancers. In addition, running consistently at a specific pace tends to improve economy at that speed (which of course necessitates that runners spend a considerable amount of time running at goal race speed prior to an important competition). The Swiss-ball’s emphasis on the development of coordination is probably on the right track, but other devices – rocker boards and wobble boards, for example – might better improve coordination during running movements, since they can be more easily utilized in a one-leg position, with a running-specific body posture, and with natural arm movements. ©

References

(1) “What Type of Strength Training Do Distance Runners Need?” Modern Athlete Coach, Vol. 40, pp. 27-37, 2002
(2) “Lumbopelvic Stability and Injury Profile in Rugby Union Players,” New Zealand Journal of Sports Medicine, Vol. 29, pp. 14-18, 2001
(3) “The Effect of Core Stabilization Training on Functional Performance in Swimming,” Master’s Thesis, University of North Carolina, Chapel Hill, 2001
(4) “Swiss Ball Exercises for Swimming, Soccer and Basketball,” Sports Coach, Vol. 21, pp. 12-13, 1999
(5) “The Role of Learning and Coordination in Strength Training,” European Journal of Applied Physiology, Vol. 55, pp. 100-105, 1986
(6) “Abdominal Muscle Response during Curl-Ups on both Stable and Labile Surfaces,” Physical Therapy, Vol. 80, pp. 564-569, 2000
(7) “The Effect of Short-Term Swiss Ball Training on Core Stability and Running Economy,” Journal of Strength and Conditioning Research, Vol. 18(3), pp. 522-528, 2004

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