Core strength training (CST) is widely used in thestrength and conditioning, health and fitness, and rehabilitation industrieswith claims of improving performance and reducing the risk of injuries (12,14).It is believed among those professionals that to improve athletic performanceand prevent risk of injury, CST is one of the vital components in the strengthand conditioning field. Despite the strong belief in these purported positiveeffects, limited scientific studies have shown no direct relationship betweenstronger core muscles and better athletic performance (3,16,17). Significantim- provement in core strength has been documented as a result of CST, but thesame research has failed to show significant changes in the athleticperformance from CST (3,16,17). This type of research indicates that CST is auseful tool for strengthening core muscles, but the carryover to mechanics andperformance needs further investigation. Core-related exercises such as Swissball training, balance training, weight training, and yoga have become popularphysical activities even among general populations in recent years. Even thoughscientific studies have not shown any links to prove performance enhancement,CST is becoming common for all levels of athletes.
In a biomechanical analysis of running, abnormalranges of vertical ground reaction forces (vGRFs) and horizontal GRFs (hGRFs)have been associated with overuse injuries (2,7,10,13). Aging, lack of jointstability, muscle weakness, harder running surfaces, and downhill running arefound to be indications of increasing impact vGRFs as well (2,5–7,18). Strongercore muscles may help keep ground reaction forces (GRFs) within an optimalrange. In addition, because previous lower-extremity injuries such as anklesprain or overuse injuries often contribute to create muscular imbal- ance andpoor proprioception, proper rehabilitation is needed to regain stability (4).Thereby, CST would be an option, and the CST may help improve dynamic stabilityof the lower extremity.
Adequate dynamic stability in the lower extremity mayhave an important role in keeping vGRFs and hGRFs within the normal range. Core strengthtraining may have an important role in running performance, such as runningwithin the normal range of GRFs at a given running velocity, and good dynamicstability of the lower extremity. Therefore, the purpose of this study was todetermine the effects of 6 weeks of CST on GRF, stability of the lowerextremity, and overall running performance in recreational and competitiverunners. We hypothesized that CST would have the following positive influences:a) decrease peak impact vGRF (initial heel contact), b) increase peak activevGRF (push-off force), c) decrease the amount of time in breaking hGRF, d)increase the amount of time in propulsive hGRF, e) increase Star ExcursionBalance Test (SEBT) scores, and f) decrease 5000-m run time.
