Effects of walking in high heeled shoes on oxygen consumption and energy expenditure in young women.
Walking is a common but complex interplay of the brain, spinal cord, muscles, foot, hips, and pelvis (5, 6). Walking while wearing high heeled shoes has become fashionable among women, which often alters the gait cycle affecting stride parameters, kinematics, muscle activity, energy consumption, and plantar foot pressure (5, 6). High heeled shoes have been reported by Stefanyshyn et al. (14) to lead to reduced stride length, walking velocity, increased stance time percentages, and decreased range of motion. The body compensates for the altered gait by increasing the activity of the gastrocnemius, soleus, and rectus femoris muscles (14). Women who wear high heels on a daily basis not only increase the risk of developing foot deformities and arthritis, but may adversely affect their posture and musculoskeletal system (10).
The appearance of women's high heeled shoes is precisely what makes the shoes uncomfortable and potentially hazardous. However, most corporate women, particularly those in managerial positions, will sacrifice comfort at the altar of high fashion, donning spikes while suffering pain and discomfort. Walking in high-heeled shoes forces the back to arch and the chest to thrust forward, causing the back and neck to hyperextend. High-heeled shoes have been found to lead to a shift in the center of gravity of the body thus altering the state of equilibrium of the body (13). This affects the body's normal posture such that the pelvis is elevated, the trunk is tilted forward and strain is put on the back muscles. In order to maintain balance, the body compensates by flexing the hip and spine causing the calf, hip, and back muscles to become tense, leading to increased muscle fatigue (13). The use of high-heeled shoes increases the risk of developing back pain, neck pain, and foot deformities (8). It has been shown that the higher the height of the heel the worse the musculoskeletal problems (8, 13). The need to generate larger muscular forces during walking increases the metabolic demand, thus oxygen consumption (V[O.sub.2]) is increased when wearing high-heels (8).
Oxygen consumption and energy expenditure have been studied in different environmental conditions and in young adults (3, 12). Banerjee and Mahindra (1) examined the energy intake and expenditure in 11 female students at a medical college, and found that ascending and descending stairs entailed more energy than cycling. Jaja et al. (9) investigated the effect of load bearing either on the back or on the chest on oxygen consumption and energy expenditure in healthy female medical students. Their results showed that carrying load on the chest may be more energy demanding than carrying the same load strapped to the back. However, studies involving the determination of oxygen consumption and energy expenditure during walking in shoes of different heel heights have not been fully studied. Therefore, this study was designed to determine and compare the effects of walking barefooted and in high heeled shoes of different heel heights on oxygen consumption and energy expenditure in young healthy women.
Twenty apparently healthy female students between the ages of 22 to 26 yrs, from the College of Medicine of the University of Lagos, South-West Nigeria, volunteered to participate in the study. None of the subjects had any musculoskeletal or neuromuscular abnormality that might make the wearing of high heeled shoes painful. The participants were experienced in wearing high heeled shoes as evidenced by self-reported wearing usage of at least twice per week. The purpose of the study was explained to each subject, which was also contained in the informed consent form. Only those who consented were included in the study. Ethical approval for this study was granted by the Research and Ethics Committee of the Lagos University Teaching Hospital, Lagos, Nigeria.
The study was conducted in the Research Laboratory of the Department of Physiology, Faculty of Basic Medical Sciences; College of Medicine of the University of Lagos.
Walking 76.5 Meters Barefooted
Upon entering the laboratory, the subjects' age, weight, and height were measured and recorded. Then, the subjects rested in the supine lying position for 30 min. Resting arterial blood pressure (ABP) and heart rate (HR) were measured and recorded using a digital sphygmomanometer (Omron, England). Oxygen consumption (V[O.sub.2]), heat production (HP) and energy expenditure (EE) were measured and recorded using the protocol of McArdle et al. (11) and Jaja et al. (9). With the subjects in the supine position, the nose was clipped and then connected to a 9-liter spirometer (SRI multipurpose spirometer) filled with 100% oxygen and with the soda-lime canister in place. The subjects breathed through one of the channels (precisely the one connected to the atmospheric air). After acclimatizing to the equipment the subjects were then switched from atmospheric air to 100% oxygen in the equipment. The subjects respired quietly for 5 min at a drum speed of 25 mm/min and thereafter disengaged from the spirometer after obtaining the required graphical representation (i.e., the expiratory points). The subjects then walked barefooted a distance of 76.5 meters in 2 min. Following the barefooted walk, the subjects assumed the supine position again to measure the cardiovascular and metabolic parameters (i.e., ABP, HR, V[O.sub.2], HP, and EE).
Walking 76.5 Meters in Different Heel Heights
The procedure described in Experiment 1 was repeated with the subjects wearing 2, 4, and 6 inch high heeled shoes. Mean arterial pressure (MAP), HR, rate pressure product (RPP), V[O.sub.2], EE were measured immediately after walking a distance of 76.5 meters in high heeled shoes of three different heel heights. The subjects were required to rest for 30 min after walking in these different heel heights. Three different shoes with average heel heights of 2, 4, and 6 inches were used in this study (Figure 1). The shoes were commercially available at the time of the study. Each shoe was chosen primarily because of the similarity of construction at the fore-foot (peep-toe) and the pointed heel. Thus, the main difference between the three shoes was the height.
[FIGURE 1 OMITTED]
Calculation of V[O.sub.2] and EE
A straight line was drawn through the tips of the graph (i.e., the expiratory points) produced as a result of the movement of the drum when the subjects were breathing through the spirometer, emphasizing the portion where the subjects were most relaxed. The slope of the line defined the subject's V[O.sub.2] (mL?[min.sup.-1]), which was corrected to standard temperature and pressure (STP). Heat production (cal?[hr.sup.-1]) was obtained by multiplying V[O.sub.2] by 0.893 (correction factor) and 4.8 (calorific value of oxygen). The EE (metabolic rate) was obtained by dividing the heat production by the body surface area ([m.sup.2]) (9, 11). Rate pressure product was obtained by multiplying SVP times HR. Mean arterial pressure was calculated by adding diastolic blood pressure to one third of pulse pressure (i.e., systolic blood pressure minus diastolic blood pressure) (2).
The data were analyzed using descriptive statistic of mean, standard deviation, and percentage. Student t-test and one-way analysis of variance (ANOVA) were used to determine significant difference. The level of significance was set at 0.05.
The age of the subjects ranged from 22.0 to 26.0 years (mean 23.8 [+ or -] 0.3 years). Height ranged from 1.5 to 1.8 meters (mean 1.6 [+ or -] 0.01 meters). The subjects' mean weight and body mass index were 61.3 [+ or -] 2.1 kg (range 49.0 to 76.0 kg) and 23.0 [+ or -] 0.9 kg/[m.sup.2] (range 17.6 to 33.2 kg/[m.sup.2]), respectively.
At Rest and After Walking 76.5 Meters Barefooted
The resting mean values for MAP, HR, RPP, V[O.sub.2], and EE are presented in Table 1. Walking a distance of 76.5 meters barefooted versus the resting condition did not have a significant effect on HR, RPP, V[O.sub.2] max, and EE. However, MAP was significantly increased (although a small difference of essentially 4 mm Hg) during barefooted walking versus resting.
Cardiovascular/Metabolic Responses Walking 76.5 Meters in 2, 4, and 6-Inch Heel Heights
Table 2 shows the cardiovascular responses of the subjects while walking 76.5 meters barefooted and in high heeled shoes of 2, 4 and 6-inch heel heights. Student t-test showed that the responses in different heel heights were significantly higher than when walking barefooted (P < 0.05). However, there was no significant difference in the cardiovascular parameters after walking a distance of 76.5 meters in high heeled shoes of 2, 4, and 6-inch heel heights.
Table 3 shows the metabolic (V[O.sub.2] and EE) responses of the subjects to walking 76.5 meters barefooted and in high heeled shoes of different heel heights (2, 4, and 6 inches). Student t-test showed that the V[O.sub.2] and EE after walking a distance of 76.5 meters in high heeled shoes of 2, 4 and 6 inches heel heights was significantly higher after walking a distance of 76.5 meters barefooted (P < 0.05) in each case. However, there was no significant difference in the metabolic (oxygen consumption and energy expenditure) responses of the subjects to walking 76.5 meters in high heel shoes of 2, 4 and 6 inches heel heights.
This study investigated changes in MAP, HR, V[O.sub.2], and EE in healthy young women (aged between 22 to 26 yrs) at rest and while walking a distance of 76.5 meters within 2 min on a horizontal plane barefooted and while wearing shoes of different heel heights.
Cardiovascular/Metabolic Responses at Rest and after Walking 76.5 Meters Barefooted
The results from the present study indicate that walking a distance of 76.5 meters barefooted resulted in a significant increase only in MAP. However, the magnitude of the increase is questionable as to having any practical significance. Walking barefooted versus resting did not change the subjects' HR, RPP, V[O.sub.2] max, and EE. Thus, the transition from rest to even light physical activity such as walking was not associated with an increase in metabolism. This finding is in agreement with the physiological expectation of an activity (such as barefooted walking) that would expect to have little to no influence on the subjects' perception of effort and/or EE given the minimal generation of muscular force during walking (3, 4, 7, 11).
Cardiovascular/Metabolic Responses after Walking 76.5 meters in Shoes of 2, 4, and 6- inch Heeled Heights
There was a significant difference in V[O.sub.2] and EE between walking barefooted and walking in high heeled shoes of 2, 4 and 6-inches heel heights. This may imply that walking in heel heights create a further cardiovascular and metabolic demands in the subjects.
The study also showed that there was no significant difference in the energy spent during locomotion using high heeled shoes of various heel heights. This may suggest that walking in high heeled shoes generally places an unnecessary demand on the cardiovascular and metabolic system of the body thereby resulting in increase in oxygen consumption and energy required in locomotion when using high-heeled shoes of various heel heights. Also the fact that there was a significant difference in the changes in the cardiovascular responses, oxygen consumption and energy expenditure of the subjects during walking in the three different heel heights (i.e., 2-inch, 4-inch, and 6-inch) may imply that walking in high heeled shoes causes unnecessary increase in MAP, HR, RPP, V[O.sub.2] max, and EE, and that the physiological burden increases with an increase in the heel heights. This finding agrees with the reports of Snyder (13), and Henry and Anastasia (8) who in their separate study exploring the effects of walking in high heeled shoes reported that the higher the heel heights, the worse the precipitating musculoskeletal problems resulting from the use of high heeled shoes. The finding of this study further suggests that walking in heel heights imposes more work on the activity of the respiratory muscles when compared with walking barefooted.
According to Stefanyshyn et al. (14), walking in heeled shoes can lead to reduced stride length and walking velocity, increased stance time percentages, and decreased range of motion. The body compensate for the altered gait by increasing the activity of the primary plantar flexor muscles (gastrocnemius and soleus), including increased activity of the rectus femoris (14). Hence, the increased metabolic activity of these muscles may contribute to the increase in V[O.sub.2] and EE. The increase in the cardiovascular and metabolic responses of the participants during locomotion in high heeled shoes of different heel heights may also be connected with an increase in greater vertical Ground Reaction Force (GRF) created by the heel heights. In fact, according to Farley and McMahon (6), vertical GRF (as opposed to horizontal GRF) is a major determinant of the metabolic cost for steady-speed level running/walking. It has also been shown that generating horizontal propulsive forces constitutes nearly half of the metabolic cost of normal walking (7).
Walking barefooted required lesser effort than walking in high heeled shoes of different heel heights, and it appears that the higher the heel heights the greater the effort required during locomotion. Walking in high heeled shoes of different heel heights also imposes more work on the activity of the respiratory muscles when compared with walking barefooted. Effort should therefore be made to encourage women, especially those who work in managerial and/or administrative careers, to reconsider the habitual use of high heeled shoes. Walking in shoes with low heel heights (not more than 2 inches) is recommended to avoid future negative effects on the musculoskeletal system.
The authors thank the female students of the College of Medicine, University of Lagos (CMUL) that participated in this study and Mr. Samuel A. Adeshina, department of physiology CMUL, for his technical assistance.
Address for correspondence: Odebiyi DO, Department of Physiotherapy, PhD, University of Lagos, City, Lagos State, Nigeria; zip-code 101014; Phone (23480 2471 7968); FAX: (234-1- 5851432); Email. firstname.lastname@example.org, email@example.com,
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Daniel O. Odebiyi , Eyitola O. Ajiboye , Smith I. Jaja 
 Department of Physiotherapy, Faculty of Clinical Sciences, College of Medicine of the University of Lagos;  Department of Physiology, Faculty of Basic Medical Sciences, College of Medicine of the University of Lagos
Table 1. Cardiovascular and metabolic responses at rest and after walking a distance of 76.5 meters barefooted. Resting Values Mean [+ or -] SEM MAP 66.59 [+ or -] 5.34 HR 74.15 [+ or -] 9.73 RPP 6872.75 [+ or -] 1084.58 V[O.sub.2] (L?[min.sup.-1]) 0.82 [+ or -] 0.23 EE (cal/hr/[m.sup.2]) 2.12 [+ or -] 0.30 Walking Barefooted Mean [+ or -] SEM MAP 70.83 [+ or -] 6.11 HR 77.75 [+ or -] 1.80 RPP 7499.42 [+ or -] 1153.30 V[O.sub.2] (L?[min.sup.-1]) 0.84 [+ or -] 0.21 EE (cal/hr/[m.sup.2]) 2.14 [+ or -] 0.52 t P-Values % Change MAP -2.34 0.02 * 6.37 HR -1.11 0.28 4.86 RPP -1.75 0.08 9.12 V[O.sub.2] (L?[min.sup.-1]) 0.09 0.94 2.44 EE (cal/hr/[m.sup.2]) 0.08 0.75 0.94 MAP--Mean arterial pressure, HR--Heart rate, RPP--Rate pressure product, V[O.sub.2]--Oxygen consumption, EE--Energy expenditure, * Significant at P = 0.05. Table 2. Cardiovascular responses after walking a distance of 76.5 meters barefooted and in shoes of different heel heights. Mean [+ or -] SD t P-value Percentage change (%) MAP (mm Hg) Barefooted 70.70 [+ or -] 6.22 2-inch heels 72.85 [+ or -] 6.07 7.49 0.001 3.04 4-inch heels 74.84 [+ or -] 5.77 7.99 0.001 5.86 HR (mm Hg) Barefooted 70.70 [+ or -] 6.22 2-inch heels 72.85 [+ or -] 6.07 7.49 0.001 3.04 4-inch heels 74.84 [+ or -] 5.77 7.99 0.001 5.86 6-inch heels 77.07 [+ or -] 6.89 9.60 0.001 9.01 RPP (mm Hg) Barefooted 7489.55 [+ or -] 1123.45 6.12 0.001 7.39 2-inch heels 8043.30 [+ or -] 1245.19 10.25 0.001 10.77 4-inch heels 8295.80 [+ or -] 1161.63 10.27 0.001 13.42 6-inch heels 8494.50 [+ or -] 1278.85 MAP--Mean arterial pressure, HR--Heart rate, RPP--Rate pressure product. (MAP: F = 0.60, P-value = 0.55; HR: F = 0.55, P-value = 0.40; RPP: F = 0.45, P-value = 0.33) Table 3. Metabolic parameters responses after walking a distance of 76.5 meters barefooted and in shoes of different heel heights. Mean [+ or -] SD VO2 max (L x [min.sup.-1]) Barefooted 0.82 [+ or -] 0.21 2 inch heels 0.98 [+ or -] 0.34 4 inch heels 0.91 [+ or -] 0.31 6 inch heels 1.11 [+ or -] 0.36 F 1.33 P-value 0.67 EE (cal/hr/[m.sup.2]) Barefooted 2.14 [+ or -] 0.53 2 inch heels 2.33 [+ or -] 0.90 4 inch heels 2.52 [+ or -] 0.83 6 inch heels 2.82 [+ or -] 1.02 F 0.56 P-value 0.33 t P-value Percentage change (%) VO2 max (L x [min.sup.-1]) Barefooted 2 inch heels 2.72 0.001 19.51 4 inch heels 3.18 0.001 10.98 6 inch heels 2.58 0.001 35.37 F P-value EE (cal/hr/[m.sup.2]) Barefooted 2 inch heels 4.80 0.001 8.88 4 inch heels 4.18 0.001 17.76 6 inch heels 3.47 0.001 31.78 F P-value Abbreviations: V[O.sub.2] max--Maximum oxygen consumption, EE--Energy expenditure
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|Author:||Odebiyi, Daniel O.; Ajiboye, Eyitola O.; Jaja, Smith I.|
|Publication:||Journal of Exercise Physiology Online|
|Date:||Dec 1, 2011|
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