1. Gender Influences on Gait when Walking Normally versus Carrying Weight Andrea L. Homan, 1 Chelsea L. Smith, 2 Emily E. Heffernen, 2 Elena E. Leon, 3 David S. Senchina 3 1 Pharmacy & Health Sciences Program, 2 Biochemistry, Cell, and Molecular Biology Program, 3 Biology Department, Drake University, Des Moines, IA 50311 ABSTRACT: Anatomically, males and females have many differences. Females tend to have a wider pelvis than males. Traditionally, males have longer limbs as well as larger muscle mass. Based on these facts, we hypothesized that females will have a larger step width and males will have a larger step length. Also, we hypothesized that the addition of carrying15% body weight would affect the males’ gait less. This study was conducted to investigate gender differences in gait. The subject was asked to walk normally across three strips of paper, and then walk across the paper again while carrying a box, which weighed 15% of their body weight. Step width and step length measurements were then taken from the ink marks on the Kraft paper. The average step length in normal walking for males was 74.8 cm and in females was 78.7 cm. When 15% of the subject’s body weight was added the average step length for males was 74.5 cm and females was 76.3 cm. In normal walking, the males averaged 7.712 cm and the females averaged 7.94 cm for step width. In walking with 15% of body weight, males averaged 8.9 cm and females averaged 8.85 cm for step width. It’s hard to make conclusions about gender differences in gait for this study because we had a limited number of subjects. But, we can conclude when a person is carrying a box full of weights versus walking normally, step length decreases and step width increases to increase one’s balance. INTRODUCTION & HYPOTHESIS: This study was conducted to investigate gender differences in gait. Gait is human foot-powered locomotion. The gait cycle contains two repeating phases: stance and swing. Stance phase is the period when the foot is in contact with the ground and swing phase is the period when the limb is elevated off the ground. Gait can describe walking, running, or jogging but in this study we will focus on walking. Anatomically, males and females have many differences. Females tend to have a wider pelvis than males. This feature accommodates the child-birthing process. In addition, this difference in pelvic width leads to an increased Q-angle in females. Q-angle is the angle at which the femur meets the tibia. Traditionally, males have thicker, longer limbs and digits. Similarly, males have a larger muscle mass than females. Based on these facts, we hypothesized that females will have a larger step width and males will have a larger step length. Step width can be defined as the distance from the ball of one foot contact to the ball of the contralateral foot contact if forward motion is ignored. Step length is defined as the distance from the ball of one foot contact to the ball of the contralateral foot contact if sideways motion is ignored. Also, we hypothesized that the addition of 15% body weight would affect the males’ gait less than the females. MATERIALS & METHODS: This study consisted of nine human subjects; four females and five males. Approval was granted before the study commenced (Drake IRB ID 09-10003). First, basic anthropometrics (age, height, weight, pelvis width [from right anterior superior iliac spine {ASIS} to left ASIS], leg length [from ASIS to ankle malleolus) were taken. Measurements were taken using standard techniques. The subject was seated and a moleskin pad was placed on the bottom of each shoe corresponding to the position immediately below the ball of the foot. Ink was then used to saturate the moleskin using a different color for each foot. Then the subject was asked to walk normally across three 7 meter-long strips of paper lined end to end with a meter of space in between to collect themselves and apply more ink to the moleskin. The subject then repeated the previous procedure carrying a box, which contained weights equivalent to 15% of their body weight. Step width and step length measurements were then taken from the ink marks on the craft paper. This procedure was then replicated for each of the other eight subjects. DISCUSSION & CONCLUSIONS: When walking normally and with the box full of weights, the females in this study had a longer average step length than the males. We predicted males would actually have a longer step length because generally males tend to have longer legs. We did, however, see a decrease in step length for both the males and females when they walked while carrying a box weighing 15% of their body weight. This makes sense because when a person has a shorter step length during gait, he or she will spend less time in single support, which is the period when only one foot is in contact with the ground. Less time on one foot means the person will have better balance. We also predicted the males would be affected less by the box of weights because they tend to have a higher muscle mass, and when looking at the decreases in step length between males and females, they were affected less. When walking normally and with a box full of weights, the females and the males both had very similar step widths. They varied less than a centimeter in both instances. We figured the females would have the greater step width because women tend to have wider hips, but it is very hard to see a significant difference. One possible reason for this lack of difference is the site where we took our measurements—the anterior iliac spine is at a spot on the pelvis opposite from the birthing canal (where we would expect to see the most pronounced gender differences in width); also, females tend to have a larger Q-angle, which counters having wider hips. But, both the males and females had an increase in step width when the weight was added. Once again this meets our expectations because by increasing the width, the person will have a stronger base and be more stable. Its hard to make conclusions about gender differences in gait for this study because we had a limited number of subjects (only 5 males and 4 females). But, we can conclude when a person is carry a box full of weights versus walking normally, step length decreases and step width increases to increase one’s balance. ACKNOWLEDGMENTS: We thank all the participants who made this study possible. RESULTS: Table: Anthropometrics by Gender Males in our study were significantly taller (p=0.007) and heavier (p=0.009) than females. As an internal control for biomechanical deviations in walking per leg, we found no differences in right vs. left leg length (p=0.86). Pelvic width, ratio of pelvic width to height, and ratio of pelvic width to leg length were not different between the genders (all p  0.1). There was no difference in the time taken to complete the 2 walking trials (p=0.96); similarly, there were no differences in the time to completion between genders within each of the 2 trials (p  0.22) Figure 1: Gender Differences in Step Length The average step length in normal walking for males was 74.8 cm and in females was 78.7 cm. When 15% of the subjects body weight was added, the average step length for males was 74.5 cm and females was 76.3 cm. The difference between genders was not significant in either condition (both p  0.48). Similarly, no differences were seen in stride length between genders for either condition (both p  0.8; data not shown). Importantly, the male step length decreased by 0.3 cm when weight was added; a decrease of.4% from their normal step length. The females step length decreased 2.4 cm when weight was added; a decrease of 3.14% from their normal step length. This assessment shows that the females decreased more than the males in both length and percentage when comparing walking normally and walking with 15% weight. Figure 2: Gender Differences in Step Width In normal walking, the males averaged 7.712 cm, and the females averaged 7.94 cm. In walking while carrying 15% of body weight, males averaged 8.9 cm and females averaged 8.85 cm. The difference between genders was not significant in either condition (both p  0.8). The males had a smaller step width than females in normal walking by 0.228 cm or 2.8%. Although, the females had a smaller step width when 15% body weight was added, 0.05cm or 0.5%. Both males and females increased their step width from walking normally to walking with weight. The females increased by 0.91 cm or 11.4%, and the males increased by 18.8 cm or 15.4%. In this comparison, the males increased more than the females in both width and percentage when comparing walking normally and with weight. Figure1: (Topmost) Shows comparison of average step lengths when walking normally and with weight for both males and females Figure 2: (Middle) Shows comparison of average step widths when walking normally and with weight for both males and females Picture: (Left) Shows a subject walking across the Kraft paper while carrying a box weighing 15% of her body weight. GenderAge (yrs)Height (cm) Weight (kg) Pelvis Width (cm) Left Leg Length (cm) Right Leg Length (cm) Shoe Weight (g) Female 21.8  3.0173.2  4.362.7  8.227.4  4.092.4  5.891.9  6.1301.6  22.4 Male 19.4  0.9182.7  3.580.8  7.132.3  3.795.9  4.395.5  5.0 416.5  154.5 (weight)