Core Issues – Reconsidered
Some seven years ago the topic of “core strength training” (CST) was covered in these pages (Article #80), with particular attention to the question of whether or not strengthening the deep trunk muscles provides any benefit to runners.
As I noted back then, many health and fitness experts advocated for the incorporation of CST to both prevent injury and improve performance. At that time, however, a review of the medical literature failed to find any compelling evidence to support this claim. Despite the very convincing logic behind this theory, there just wasn’t enough scientific proof to warrant a wholehearted endorsement of the practice.
I did state then that I was hopeful that “the passage of time will produce verification of the claims of those who believe fervently in this theory,” and indeed, at least one recent study has borne some fruit for those who promote these exercises.
A 2009 study conducted at Barry University in Florida addressed the issue from both sides; they hypothesized that core training would have positive influences on factors previously identified as being associated with increased injury rates in runners, and would also improve running performance. Specifically, these measures included (1) ground reaction forces (impact), (2) stability of the lower extremity; and (3) 5,000 meters running time.
Limiting the subjects to those testing deficient on a standardized stability test, 28 runners who qualified for the study were divided into two groups. Both groups continued their regular training regimen, but only one group added a formalized program of exercises – 5 in all– to improve core strength and stability. The exercises were:
- Abdominal crunch on a stability ball to target abdominal muscles.
- Back extension on a stability ball to target back extensor muscles.
- Supine opposite 1-arm/1-leg raise to target back/hip extensor muscles.
- Hip raise on a stability ball to target back/hip extensor muscles.
- Russian twist on a stability ball to target abdominal muscles.
After 6 weeks, both groups were tested for changes from their initial scores in the 3 categories. The results showed no significant changes in the experimental group in ground reaction forces experienced with running, or in the performance of lower extremity stability tests, both of which being indicators of risk for injury. (Of course, an “indicator” is not quite the same as gathering data on actual injury numbers – a more extensive, long-term study with greater numbers of subjects would be needed – but it does suggest that core strengthening may not provide this hoped-for benefit.)
On the other hand, the study did show that those in the experimental group saw a significant improvement in their 5,000 meter time, while the control group saw only minor, insignificant improvements. The investigators took care to test both groups under the same conditions, to avoid advantages that might have been gained from environmental (temperature, humidity) differences.
While this is an encouraging development, a critical evaluation of this study raises the usual caveats – small sample size, application to only one event (would this work for a marathon? 400 meters?), duration of the training – that warrants caution for making a blanket statement endorsing core strength training as a means of improving running performance. But, as I stated last time, there really is no downside to these exercises, so have at it.
Sato, K.; Mohka, M. Does core strength training influence running kinetics, lower-extremity stability, and 5000-m performance in runners? Journal of Strength and Conditioning Research, 23:1 Jan 2009.