Relationship between leg length and energy expenditure during walking

Abstract

IntroductionWalking is a major daily physical activity for almost all healthy individuals. Walking is one of the most recommended physical activity due to its simplicity, inexpensiveness, and being widely accepted by the society and can be incorporated into daily life and sustained until old age (Bird, Radermacher, Sims, Feldman, Browning & Thomas 2010). Walking is a complex functional skill that is a result of the integration of physical characteristics, skeletal, muscular and nervous systems as they interact with the environment. Any imbalances of these systems is likely to cause an increased in energy cost (Rose & Gamble 2006). American College of Sport Medicine (ACSM) has made it known to the public that at least 30 minutes od moderate intensity physical activity, five times a week is recommended to promote health and increase lifestyle activity (ACSM 2009). Physical activity need not only occurred through sports or gym-based exercises, but also through lifestyle based activities such as walking (Gilson, McKenna, Cooke & Brown 2007). Another study conducted by Mackey, Bohle, Taylor, DiBiase, McLoughlin and Purnell (2011) stated that walking has been described as a near perfect exercise, in that its energy expenditure can be one of the best approaches to monitor individual's health, based on walking efficiency. The Healthy People 2010 initiative, a recommendation originating from Tokyo, Japan and adopted by the United States public health agencies, recommended 10,000 steps per day (Macpherson, Purcell & Bulley 2009). For an adult, approximately 1,800 - 2,200 steps equals to 1.6 kilometer. Research showed that adults walk approximately 3 to 5 kilometers (4,000 to 6,000 steps) per day (Laurson, Eisenmann, Welk, Wickel, Gentile & Walsh 2008; Welk, Differding, Thompson, Blair, Dziura & Hart 2000), and people must, on the average walk an additional 4,000 steps. The duration for walking 4,000 steps at a brisk pace could be achieved in approximately 30 minutes (Weary 2007) which is equivalent to the physical activity level recommended by the Centers for Disease Control and Prevention, and the ACSM.Energy expenditure of any group in a population is determined by the structure of the group (age, gender, body mass, stature), the patterns of physical activity and the climate (Manini 2010). Therefore although most studies have found different results about differences in energy expenditure (per unit kilogram/time) with regard to physical characteristics and gait parameters, how walking gait should be adapted to minimize energy expenditure and how walking activity should be continously planned to keep energy cost as low as possible without stopping or early onset of fatigue should be researched. For the past twenty-five years, it has been generally accepted that energy expenditure of human body is an important criterion in studies of exercise physiology and diseases such as obesity, diabetes, hypertensions and in preserving lefespan (DeLany & Lovejoy 1996; Maddison 2007; Titze, Martin, Seiler, Stronegger & Marti 2001). The assessment of energy expenditure of walking in real life has become increasingly important, since it may help to identify inactive lifestyles and motivate towards more active lifestyle.Gender is a factor that influences movement patterns during walking (Chiu & Wang 2007; Chung & Wang 2010). Even though their research findings suggest that higher energy expenditure demand is displayed by males and is related to the presence of a greater muscle mass at a given speed, Kito and Yoneda (2006) indicated that small stride length increases energy expenditure. Speed is one of the significant factors that directly affect energy expenditure. While the speed formula defines speed as the multiplication of stride length and stride frequency, it is apparent that modifications of stride length and stride frequency as the speed changes affect the energy expanded during walking (Rose & Gamble 2006). …