A-56 Free Communication/Poster - Running Wednesday, May 31, 2017, 7: 30 AM - 12: 30 PM Room: Hall F
Recent literature suggests a transition from rear-foot striking (RFS) to mid-foot striking (MFS) may lower injury potential; but transition is difficult. Using a resistive proprioceptive device may facilitate the change. No study has quantified the impact of such a device on foot-strike conversion.
PURPOSE: To examine the effectiveness of a 6-week MFS drill training program in converting recreational RFS to MFS with and without the use of a proprioceptive resistive device (EZ Run Belt) using changes in cardiovascular, biomechanical, and neuromuscular assessments.
METHODS: 19 RFS runners were randomly assigned to control (C: M4, F1), drills only (DO: M3, F4), or drills plus belt (DB: M6, F1) groups. Both DO and DB received drill sessions using MFS training over 6 weeks with DB using a resistive belt (EZRB) during training runs. Physiological (VO2max, anaerobic threshold, heart rate, running economy, timed performance), biomechanical (knee flexion and dorsiflexion angles at initial contact (KFA, DFA), cadence (CAD), stride length) and electromyographic (EMG) measures of 5 right-leg muscles (rectus femoris (RF), vastus lateralis, biceps femoris (BF), semitendinosus (ST), and lateral gastrocnemius (LG), were recorded as subjects ran under 3 conditions: submaximal (85% lactate threshold heart rate) on a treadmill (TM85) and overground for 400m (OUT85), maximal overground (OUTMAX), before and after training.
RESULTS: In all 3 conditions, outcomes reflected significant within-group increases for DO and DB in CAD and EMG and decreases in KFA, DFA consistent with an RFS to MFS conversion, but no significance was detected between DO and DB, except for the RF EMG during TM85 increasing for DO and decreasing for DB (-.014±.005 μV, p<.05). Greatest changes in DO were observed at OUT85: RF (+66%, p=.045), BF (+70%, p=.008), LG (+49.6%, p=.05), KFA (-3.9%, p=.001) and DFA (-34.3%, p<.001). Greatest changes in DB were observed at OUTMAX: BF (+84.4%, p=.003), ST (+85.5%, p=.015), CAD (+5.3%, p<.001), KFA (-4.9%, p<.001).
CONCLUSIONS: Changes in biomechanics and muscle activation observed in DO and DB indicate a significant shift from RFS to MFS after 6 weeks of MFS drill instruction, unique effectiveness of the proprioceptive device could not be established, but differences warrant further investigation.