COMPARISON OF TWO BACKPACK DESIGNS USING BIOMECHANICAL AND METABOLIC ASPECTS OF LOAD CARRIAGE

The purpose of this study was to compare the compartmentalized backpack to a control backpack using metabolic and biomechanical parameters. Thirteen apparently healthy female subjects were asked to carry a load while walking on a treadmill at 1.3 m/s for 27 minutes with both the compartmentalized backpack and a control backpack. Parameters for comparison were oxygen consumption (VO2), respiratory exchange ratio (RER), mean head and trunk angles, stride length, and stride rate. There were no significant differences in parameters between the compartmentalized pack and the control pack, but differences were found in VO2 and RER with fatigue. These results suggest that the load distribution of the compartmentalized pack was comparable to the control pack

MOTION ANALYSIS: ONE VERSUS TWO STRIDE ANALYSES

The purpose of this study was to analyze two consecutive strides and compare results of gait and posture between the first stride, second stride and mean of the two strides. Two strides were filmed and digitized for 36 children at both 100m and 900m on three separate occasions. Head and trunk f1exion, stride length, stride rate and double support time were recorded. No significant differences were found between the first, second and mean of the two strides for trunk! head flexion and stride length. Differences were recorded between the first and second stride in stride rate and double support time, although neither stride was significantly different from the mean of the two strides. It was concluded that only one stride need to be digitized for an accurate representation of posture and gait

EFFECTS OF BACKPACK DESIGN AND FATIGUE ON POSTURE IN CHILDREN

The purpose of this study was to determine which hip bell/frame sheet combination reduced postural changes associated with load carriage in children. Thirty-six 10·12 year olds walked 1000m around a track in 3 randomly assigned hip belt and frame sheet conditions. Two strides were digitized at 100 and 900m with mean head and trunk angles, as well as posture across the gait cycle recorded. Hip belt and frame sheet design did not alter head flexion separately, but interaction between the design features indicated less compromise in posture with the Back Balancer. The solid and padded frame sheet reduced counterbalance of the weight in the trunk

ANALYSIS OF GROUND REACTION FORCES PRODUCED IN BASKETBALL MANEUVERS OVER A SEASON

The purpose of this study was to determine differences in ground reaction forces of college basketball players over a season. Eleven male Division III basketball players performed eight directional basketball maneuvers in random order on an AMTI© 1000 force plate. Subjects were tested every two weeks over an eight week period. Typical ground reaction force curves for vertical, medial/lateral and anterior/posterior were obtained. Results indicated no significant changes occurred across the group, however individual changes were apparent for some subjects, predominantly in the shuffle movements. This study concluded that there were no significant differences across subjects but individual differences in ground reaction force data did occur in some subjects

CENTRAL AND PERIPHERAL FATIGUE IN WOMEN ATHLETES

The purpose of this study was to compare the EMG activity in central and peripheral fatigue protocols with the knee’s dynamic stabilizers. Twelve women in the central fatigue group completed a soccer game simulation protocol, while 13 women completed a maximal weight lifting protocol. EMG of the rectus and bicep femoris were taken in a rested and fatigued state. A repeated measures 2x2 ANOVA (α = 0.05) were used for comparison of average rectified values (ARV) and frequency data. The rectus femoris saw decreases in ARV and increases in frequency with fatigue with both central and peripheral fatigue. The bicep femoris had decreases in ARV and frequency with fatigue in central fatigue, while with peripheral fatigue both ARV and frequency increased

DIFFERENCES BETWEEN GENDERS DURING PLYOMETRIC JUMPS

The purpose of this study was to compare men’s and women’s landing kinetic and kinematic parameters during plyometric jumps. 22 females and 7 males performed jumps from three heights while being videoed in the sagittal and frontal planes of motion. Force data for the right foot were also recorded. Maximal hip, trunk, knee, ankle and valgus angles were recorded, as well as peak vertical, medial/lateral forces and total contact time. Women land in a more upright posture with significantly more valgus than men. Peak vertical forces did not differ between the sexes, but mean maximal medial/lateral forces were higher in the females. Box height was not a factor in kinematic results, but the medium box showed significantly lower medial/lateral forces in both sexes. The men spent significantly less time in contact with the ground

COMPARISON BETWEEN GROUND REACTION FORCE PATTERNS AND ANGULAR, APPROACH, AND BALL VELOCITIES FOR IN-STEP KICKING

The purpose of this study was to determine if patterns in vertical ground reaction forces resulted in differences in hip, knee and trunk angular velocity and efficiency of the open kinetic chain. 20 subjects performed a maximal in-step kick while ground reaction forces of the plant leg, as well as angular, approach and ball velocities were recorded. Although approach and ball velocity did not change between groups, the decreasing vertical force group had significantly higher initial peak vertical ground reaction forces and angular hip velocities than subjects with a double vertical peak pattern. There was a significant relationship between approach velocity and ball velocity, as well as a negative relationship between posterior lean on contact and leg angular velocity. It seems that the pattern of vertical force with the plant leg is not a key factor in ball velocity

ARM SWING IN CHILDREN CARRYING BACKPACKS

Arm swing during walking helps maintain balance and reduce twisting of the trunk. By limiting horizontal excursions of the body, arm swing aids in maintaining horizontal velocity (Hinrichs, Cavanagh, & Williams, 1987). When arm swing is restricted, it is predicted that there will be a greater degree of torque placed on the vertebra, increasing pressure on the intervertebral discs (Jackson, 1983; Li et aI., 2001). This may be exaggerated when adding weight, specifically to the trunk, such as when carrying a backpack. Arm swing not only aHects torsion on the spine, it also influences the lower limbs. Reciprocal swinging of the arms has been directly tied to stride rate. As arm swing is restricted, stride rate tends 10 increase (Eke-Okoro, Gregoric, & Larsson, 1997). Increased vertical ground reaction forces have also been tied to fixed-arm walking (Li et aI., 2001). Li et al. (1996) found differences between adults and children 9 years of age as they corresponded to centre of pressure under the foot. These differences were attributed to torques induced by the lower limbs because arm swing was restricted in children's walking patterns. The purpose of this study was to determine the amount of arm swing in children during load carriage

GENDER DIFFERENCES IN GROUND REACTION FORCES DURING RUNNING AND AGILITY-TYPE MOTIONS

Foot and gait characteristics are different between genders. The purpose of this study was to determine if gender has an effect on ground reaction force characteristics during running and agility-type motions. Twenty-two apparently healthy female (73.8±8.4kg; 1.74 ±0.06 m) and seven male (73.5 ±5.3 kg; 1.68 ±0.02 m) current or recently graduated NCAA Division III athletes voluntarily participated in this study. Subjects wore a volleyball shoe while performing four different actions: running, cutting, shuffling, and back cutting. Three 2x4 repeated measures ANOVAs (

GROUND REACTION FORCES PRODUCED IN BASKETBALL MANEUVERS WITH NEW AND STRUCTURALLY DAMAGED SHOES

The purpose of this study was to determine the difference in ground reaction forces between new shoes and shoes with obvious structural damage. Six male Division III basketball players performed eight directional basketball maneuvers in random order on an AMTI© 1000 force plate. Subjects were tested when the shoes were new and after the shoes had structural damage. Results indicated that forces were significantly higher in new shoes than damaged shoes (vertical: left forward, peak-1; left shuffle, peak-2; left back, peak-1 and ms; medial-lateral: left shuffle, peak-2; anterior-posterior: forward, peak-2; left back, peak-1; back, peak-1). No significance was found in time to peak forces or total time. This study concluded that new shoes showed significantly higher forces than shoes with obvious structural damage