INTRODUCTION:Common warm-up techniques attempt to prepare the body for tasks that may require higher physiological response. The increase in temperature with warm-ups tends to speed nerve conduction velocity, attenuate muscle spindle sensitivity, and decrease tissue stiffness. Passive (hot pack or massage) or active (low intensity aerobic) warm ups that target the specific joint or muscle may be more effective than general body warm-ups. Localized hot pack application and joint mobilizations may better stimulate musculotendinous tissue thereby allowing more effective preparation for tasks that require a high neurological response. PURPOSE:The purpose of this study was to investigate what type of warm up is most effective at improving single leg stance mechanics and dynamic balance as assessed by the Y- balance test. METHODS:Six men and six women (age yr; 169.0±8.5cm; 77.7±16.3kg) volunteered for study. Four subjects were randomly assigned to one of the three groups: hot pack (HP), manual therapy (MT), or stationary cycle (SC). Three tests including eyes open single-leg balance (EOSLB) and eyes closed single-leg balance (ECSLB) on force plate and the dynamic Y-balance Test (YBT) were used to assess balance before and after different types of warm-up. Force plate recorded total distance, radial area, medial/lateral (x) and anterior/posterior (y) ranges and frequencies. For HP, a 170 ﹾ hydrocollator pack was applied for 20-minutes to the calf and ankle. For MT, anterior glides and posterior glides of the tibiofemoral and talocrual joints, traction of the talocrual joint, and 10-minutes of massage were applied to the calf and ankle. The SC group rode the bike at 50rpm and 1kp for twenty minutes. A 3x2 repeated measures ANOVA was done using SPSS 19 (α<0.05). RESULTS: For EOSLB, there was a significant time main effect for total distance (F1,36=5.7, p=0.022), x frequency (F1,36=4.6, p=0.038), and y frequency (F1,36=4.4, p=0.043). Total distance decreased (48.2±2.8cm to 41.3±1.7cm) and the frequencies decreased (for x, 0.9±0.09Hz to 0.8±0.06Hz and for y, 0.9±0.09Hz to 0.7±0.06Hz). For ECSLB, there was a time x group interaction for radial area (F2,43=3.8, p=0.029). The radial area for the HP group increased (4.9± 0.6cm2 to 6.8±0.6cm2). For the YBT, there was a time main effect (F1,8=5.6, p=0.041). All subjects improved their YBT score regardless of type of warm up. CONCLUSION:The type of warm up performed did not affect testing conditions with eyes open (EOSLB and YBT); however, the process of warming up improved dynamic and static balance and subjects became steadier. Balance improved because the subjects’ total distance traveled decreased significantly as did x and y frequencies. The type of warm up did affect the ECSLB because only the HP group experienced any specific changes in their ability to control balance. The hot pack reduced musculotendinous stiffness allowing a greater range of mobility with decreased changes in direction. Laine S, Trowbridge CA, Ricard MD The University of Texas at Arlington, Arlington, TX Department of Kinesiology · Biomechanics Laboratory THE EFFECT OF WARM-UP TECHNIQUES ON FOOT, ANKLE AND LOWER LEG STABILITY IN A COLLEGE-AGE POPULATION Methods The purpose of this study was to investigate what type of warm up is most effective at improving single leg stance mechanics and dynamic balance as assessed by the Y- balance test. There are a variety of warm up techniques in practice. Through investigation, the physiological aspects involved in balance are highlighted. Purpose Abstract Results Results (cont’d)Methods (cont’d) Conclusion There were twelve subjects: 4 in each of the three groups (Table 1). The type of warm up did affect the EC SLB because only the HP group experienced any specific changes in their ability to control static balance. The hot pack seems to have reduced musculotendinous stiffness thereby allowing a greater range of mobility (Figure 5). While not significant, it was interesting that total distance decreased in the MT group (Figure 4). This is an area for more study. The type of warm up performed did not affect testing conditions with eyes open (YBT and EO SLB ); however, the process of warming up improved dynamic and static balance and subjects became steadier while standing on a force plate. Dynamic balance improved because the subjects’ Y-balance composite score increased (Figure 6). Subjects became steadier during static balance because total distance traveled decreased (Figure 8) and they wobbled less (Figures 7 & 9). Table 1: Subject Demographic Information. hot pack (HP), manual therapy (MT), or stationary cycle (SC) Each subject came in for 3 total sessions: 2 familiarization sessions and 1 testing session. Pre and Post Testing 1. Single-leg Balance Test (SLB) o Equipment: Force plate and Balance analysis program o Dependent variables: Total distance, Radial area, Medial/lateral (x) range and frequency, Anterior/posterior (y) range and frequency (Figure 1&2) 1a. Eyes open condition (EO SLB ) 1b. Eyes closed condition (EC SLB ) 2. Y-balance Test (Figure 3) o Equipment: Tape and Tape measure o Consists of 3 reaches: anterior, posterior medial, and posterior lateral o Composite score %: sum of the reaches divided by 3x stance leg length Treatment Three separate groups o Hot pack (HP)- 170 ﹾ hydrocollator pack was applied for 20-minutes to the calf and ankle o Manual therapy (MT)- anterior glides and posterior glides of the tibiofemoral and talocrual joints, traction of the talocrual joint, and 10-minutes of massage were applied to the calf and ankle o Stationary cycling (SC)- rode the bike at 50rpm and 1kp for 20 minutes A 3x2 repeated measures ANOVA was done using SPSS 19 (α<0.05). Figure 4: EC SLB Mean Total DistanceFigure 5: EC SLB Mean Radial Area Figure 9: EO SLB Frequency of Oscillations in Anterior/Posterior (y) Range Figure 6: Y-balance Test Score Figure 7: EO SLB Frequency of Oscillations in Medial/Lateral (x) Range Figure 8: EO SLB Total Distance HP groupMT groupSC groupTotal Age (years)23±222±123±4 Height (cm)171±16165±14171±6169±11 Weight (kg)73±2170±1791±3878±16 Male3126 Female1326 Figure 3. Y-balance Test Figure 1. Total Distance Figure 2. Radial Area