Analysis of Push-Up and Pull-Up Variants to Develop an Upper Extremity Model

Musculoskeletal Injuries are the most common cause of severe long-term pain and physical disability. Push-Ups and Pull-Ups are effective dynamic exercises that mimic high level function activities, such as those used in the military. The model developed allows for researchers to analyze the forces and moments associated with the shoulder, elbow and wrist, to further assess function in military personnel, athletes and the active population. The model also follows the guidelines set forth by the International Society of Biomechanics (ISB)

MUSCLE SYNERGY DURING A SINGLE LEG STANDING TEST IN AMBULATORY CHILDREN WITH CEREBRAL PALSY

INTRODUCTION: Cerebral Palsy (CP) is a sensorimotor disorder characterized by dysfunctional motor coordination, balance problems, and loss of selective motor control. Motor coordination exhibited as co-contraction, has been subjectively quantified using gait analysis, but recent studies have begun to objectively analyze the amount of co-contraction by collecting electromyography (EMG) data. Center of pressure excursion (COPE) measurements collected during a single leg standing test (SLST) have shown to be more valid measurements of balance in populations with motor disabilities than a SLST alone. A recent study has correlated increased COPE velocity with a lower fall risk as determined by reported fall frequency, suggesting a more objective measure of fall risk. The current study aimed to determine if the fall risk calculated by COPE velocity in children with CP is correlated with co-contraction index value in various muscle synergy groups. It was hypothesized that i) co-contraction index values will differ between high and low fall risk groups, ii) there will be preferential activation of different synergy groups within the high and low fall risk groups, and iii) there will be a negative and direct correlation between COPE velocity and co-contraction index values for all synergy groups. METHODS: Fall risk grouping was determined by average COPE velocity values calculated from previously reported fall frequency groups. Balance ability was determined by COPE measurements during a SLST on a force plate. Muscle synergy groups were determined by common muscle pairings at the hip, knee and ankle. Co-contraction indices were determined from linear envelopes plotted from muscle group EMG data. An independent t-test was run on muscle synergy groups between high and low fall risk groups. Nonparametric Analysis of Variance (ANOVA) and Tukey post-hoc tests were run on the high and low fall risk groups separately to determine differences in co-contraction index value within high and low fall risk groups. A Pearson correlation analyzed COPE velocity and co-contraction index value. RESULTS: No significant differences in muscle synergy between the high and low fall risk groups were found (p = 0.476, 0.076, 0.064, 0.364). The ANOVA and Tukey post-hoc tests for high fall risk group found significant differences in co-activation index value between the sagittal hip and frontal hip groups (p = 0.022) and sagittal hip and ankle groups (p = 0.016). Low fall risk group was found to have significant differences between the sagittal hip and frontal hip groups (p = 0.038) and frontal hip and knee groups (p = 0.012). Weak and negative correlations were found between COPE velocity and both knee and ankle groups (r = -0.309, -0.323, p = 0.059, 0.050). Negligible and insignificant correlations were found between frontal hip and sagittal hip synergies and COPE velocity ((r = 0.013, -0.068, p = 0.475, 0.367). CONCLUSION: There is insufficient evidence to claim that muscle group activations are different depending on fall risk grouped by COPE velocity. It is not currently possible to correlate COPE velocity to a specific synergy group recruitment. However, data do suggest that sagittal hip and knee strategies are recruited more than ankle and frontal hip strategies during SLST

Utjecaj policijskog treninga na razinu doživljenog stresa policijskih službenika

Utjecaj policijskog treninga na razinu doživljenog stresa policijskih službenik

QUANTIFICATION OF IN-PLAY COMPETITION DEMANDS OF COLLEGIATE AMERICAN FOOTBALL PLAYERS USING GLOBAL POSITIONING SYSTEMS

There is limited information describing the competition demands of American football. A greater understanding of competition demands will allow strength and conditioning practitioners to create appropriate training programs to enhance athlete readiness and performance. Therefore, the purpose of this study was to analyze the competition demands of collegiate American football players using global positioning systems (GPS), specifically comparing the in-play GPS versus out-of-play GPS outcomes. Twenty-two American football athletes (Age: 20.8 ± 0.9 yr, Height: 190.2 ± 4.7 cm, Body mass: 113.4 ± 22.3 kg) were monitored during 12 regular season competitions over 13 weeks. Athletes were divided into specific offensive and defensive position groups. The study utilized relative velocity zones to determine the distance traveled by athletes in different velocity zones. In-play GPS variables were stratified from out-of-play GPS variables using velocity tracings from Openfield software and competition video. Paired samples T-tests were used to identify differences between in-play and out-of-play variables. The findings indicate that total duration, total distance, standing distance, walking distance, and jogging distance were significantly lesser for in-play versus out-of-play (p \u3c 0.001), and extensive tempo distance, intensive tempo distance, sprint distance, and intensity were significantly greater for in-play versus out-of-play (p \u3c 0.001). The results of the present study provides novel insights regarding the in-play competition demands of collegiate American football and provides a different method of analyzing American football

CENTER OF PRESSURE EXCURSION DURING A SINGLE LEG STANDING TEST IN AMBULATORY CHILDREN WITH CEREBRAL PALSY

INTRODUCTION: Cerebral Palsy (CP) is the most common disabling motor disorder found during childhood, occurring in 2.1-3.2 of every 1,000 births. Motor functionality of children with CP is commonly compromised and is classified with a gross motor function classification score (GMFCS) and with the gross motor function measure (GMFM). Balance ability has typically been assessed using single leg stance test (SLST) time but more recently, center of pressure excursion (COPE) has shown to be a more valid measurement in populations with altered motor abilities. However, COPE has not been used to test balance in the CP population, yet. This study aimed to determine if relationships were present between COPE measurements, functionality measurement scores (GMCS and GMFM) and reported fall frequency. It was hypothesized that i) larger COPE measurements would be associated with a higher GMFCS level and lower GMFM score, and that ii) COPE measurements would be significantly higher in children with a high reported incidence of fall frequency. METHODS: Gross functionality was measured using a GMFM score and GMFCS level. Balance ability was assessed using COPE measurements on a force plate and SLST time. Fall frequency was determined by a short questionnaire. A Pearson correlation analyzed COPE measurements vs. mean GMFM score. A one-way ANOVA was used to compare COPE measures between GMFMCS levels, with a Bonferroni post-hoc test. Lastly, an independent sample t-test analyzed differences in COPE measurements and SLST time between fall frequency groups. RESULTS: Significantly larger COPE velocities were demonstrated in children who reported a greater number of falls in the past month and were considered high risk for falling (p = 0.02). No relationships were demonstrated between COPE measurements and GMFM score. GMFCS level III participants demonstrated statistically significant lower COPE velocity compared to GMFCS level II participants (p = 0.05). There were no significant differences in SLST between high and low risk fall groups (p = 0.07). DISCUSSION: Children with higher reported fall frequencies demonstrated a 60% increase in COPE velocity, compared to those with little to no falls. Clinical GMFM scores did not demonstrate significant correlations to COPE measurements and may not be an appropriate identifier for falling in children diagnosed with CP. This is the first trial to evaluate COPE measurements and reported fall frequencies in children diagnosed with CP. The use of a force plate to determine COPE velocity during a SLST is useful in identifying children with CP who may be at an elevated risk for experiencing a fall. COPE velocity was able to provide intricate quantitative data regarding fall risk that could not be obtained during a normal SLST

INTRA- AND INTER-RATER RELIABILITY OF MAXIMUM TORQUE APPLIED DURING PASSIVE ELBOW RANGE OF MOTION TESTING POST-CASTING OF SUPRACONDYLAR AND LATERAL CONDYLAR FRACTURES IN CHILDREN

Elbow fractures account for a significant number of pediatric orthopedic injuries. The most common of these are the supracondylar and lateral condylar humeral fractures. When surgical repair is necessary casting and pinning of the elbow can affect the elbow’s range of motion (ROM), so recovery is monitored. Practices for measuring recovery are not standardized so measures may not be consistent. A possible novel measure to help account for different clinicians participating in the same study is maximum torque applied during elbow end ROM testing. This study uses several comparisons of maximum torque applied by three different clinicians during end ROM testing on a sample of twenty-seven pediatric patients. Multiple mixed ANCOVAs and pairwise comparison models of maximum torque applied to assess the reliability of applied torque. Significant differences were only detected during six-month follow up appointments, and the twelve-month post-cast removal follow-up appointment. Significant differences in torque applied during tests of both flexion and extension end ROM of both the involved and uninvolved limb were seen mostly attributed to one participating rater. A paired t-test was conducted between the maximum torque measures taken during tests of both the involved and uninvolved limb. No significant difference was found in maximum applied torque. In addition, a two-sample t-test comparing the mean differences in maximum torque applied during the end ROM tests by the same or by different clinicians found no significant difference. While differences were noted in the pairwise comparisons between rater one and the other two during later appointments this could be because of the experience of this one rater with the test and their level of comfort performing it when further removed from incident of injury. If future studies on maximum torque in passive elbow ROM testing are carried out a larger group of patients will be needed to make comparisons between raters and visits. Other studies could also use multiple raters at one visit allowing for a direct comparison of maximum torque

Susceptibility to Ankle Sprain Injury between Dominant and Non-Dominant Leg During Jump Landings

Ankle sprains are one of the most common injuries within athletics in the United States with approximately one-million student athletes experiencing ankle sprains each year. Studies argue excessive or rapid ankle inversion occurring from jump landings may cause ankle sprains. Also, the effect of limb dominance on risk of ankle sprain is not well documented. The aim of this study was to determine if there is an affect of leg dominance on landing mechanism of the ankle joint that predisposes either ankle joint to greater risk of ankle sprain. Twelve recreationally active subjects were recruited and completed four maximal vertical jumps. Ground reaction force, marker position data and maximal vertical jump height were collected using two Bertec Force plates, a 10-camera motion capture system, and a Vertec Vertical Jump Trainer, respectively. Cortex and Visual3D software programs were used to process the motion capture data and to calculate peak vertical ground reaction forces(vGRF), loading rate, and ankle joint moments. There were no statistically significant differences in ankle joint moment or loading rate between limbs, but peak vGRF were significantly higher (p \u3c 0.05) in the non-dominant ankle. The results suggest the non-dominant ankle displays higher injury potential, as the non-dominant leg accumulates a larger peak landing force

Static Stretching and Preconditioning Exercise Augments Power Output in Recreational Athletes

The purpose of this study was to determine the independent and combined effects of performing a preconditioning exercise and antagonist stretching on vertical jump (VJ) performance. Twenty club rugby players performed a VJ in four conditions: control condition, following static stretching, following a preconditioning exercise, and following the combined treatment of static stretching and a preconditioning exercise. Electromyographic (EMG) activity was measured in the gluteus maximus, vastus lateralis, gastrocnemius medialis, and tibialis anterior during the VJ trials. Repeated measures ANOVA were used to compare VJ and EMG outcomes across conditions. A Bonferroni correction was used to account for multiple post-hoc comparisons (significance set at p \u3c 0.0083). Despite a strong trend, there were no independent effects of performing the preconditioning exercise (p = 0.012 / Effect size = 0.29) and static stretching (p = 0.050; Effect size = 0.19) on VJ height compared to the control condition. However, the combined treatment increased VJ height 1.59 ± 1.42 cm compared to the control condition (p \u3c 0.001, Effect size = 0.57). There were no significant differences in EMG outcomes between conditions. These findings indicate that performing a preconditioning exercise and statically stretching the antagonist muscles acutely augments lower body power output

RELATIONSHIP BETWEEN PHYSICAL FITNESS MEASURES AND OCCUPATIONAL PHYSICAL ABILITY IN UNIVERSITY LAW ENFORCEMENT OFFICERS

Law enforcement on academic campuses can be a physically demanding profession. Law enforcement officers (LEOs) may be required to perform a variety of physical tasks. Identifying which physical fitness characteristics are associated with these tasks will guide the development of appropriate and effective exercise programs. Therefore the purpose of this study was to identify physical fitness and demographic characteristics associated with the occupational physical ability of university LEOs. Sixteen male LEOs (age: 33.1±8.7 yr.; body mass: 87.2±11.2 kg; height: 178.9±7.9 cm) performed an officer physical ability test (OPAT) that simulated a foot chase of a suspect. In addition, the officers completed a battery of physical fitness tests that assessed aerobic and anaerobic capacity, muscular endurance, strength, power, flexibility, agility, and body composition. The OPAT was correlated with agility, upper body muscular endurance and strength, torso endurance, lower body power, aerobic endurance, and relative body composition (p\u3c0.05). In addition, the OPAT was correlated with the following demographic and anthropometric variables: age, work experience, and waist and abdominal circumferences (p\u3c0.05). In conclusion, tactical strength and conditioning professionals must design exercise programs for university LEOs to improve multiple components of physical fitness and focus on weight management

THE EFFECTS OF GOLF STANCE ON THE PEAK KNEE ADDUCTION MOMENT DURING THE GOLF SWING

INTRODUCTION: The knee joint is one of the most frequently injured structures in the game of golf. The loads experienced by the knee during the golf swing are typically greater than those experienced during walking. In particular, a heightened lead limb peak external knee adduction moment has been linked to the progression of medial compartment knee osteoarthritis (OA). Altering movement patterns is a common strategy that can be used to reduce loading on the knee joint but has received little attention during the golf swing. Also, while such manipulations may be beneficial from an injury prevention perspective, they may have implications on golf performance. The purpose of this study was to analyze the effects altering stance has on the peak knee adduction moment and swing speed during the golf swing. METHODS: Twenty healthy subjects were recruited for a 3-dimensional biomechanical analysis wherein participants hit three golf shots using different stance positions in which either foot angle or stance width was altered. The following stance conditions were used: self-selected, 0º foot angle (perpendicular to target line), 30º foot angle (externally rotated), wide stance width, and narrow stance width RESULTS: Both the 30º foot angle and the wide stance width significantly decreased (p \u3c 0.001) the lead limb peak external knee adduction moment compared to the self-selected golf stance. In contrast, the narrow stance width significantly increased (p = 0.023) the peak knee adduction moment when compared to the self-selected stance. No significant differences were found in the peak knee adduction moment between the 0º foot angle and self-selected stance. Lastly, no significant differences (p = 0.109) were found in swing speed between any of the stance conditions. CONCLUSION: The externally rotated foot position and wider stance width decreased the lead limb peak knee adduction moment without hindering performance. Considering the prevalence of injury to the lead limb knee joint, modifying a golfer’s stance could potentially be used to increase the longevity of their playing career