The energy cost of women walking and running in shoes and boots∗

The purpose of this study was to determine the difference in energy cost for women walking and running in shoes versus heavier boots. Seven subjects wore athletic shoes (mean weight = 514 ± 50g) and leather military boots (mean weight = 1371 ± 104g) at three walking speeds (4·0, 5·6 and 7·3km/hour) and two running speeds (8middot;9 and 10·5 km/hour). During each walking and running trial oxygen uptake ([Vdot]O₂ ml kg^?1 min^?1) was measured. The [Vdot]O₂ for women wearing boots were significantly higher (P < 0·05) than for shoes for both walking and running, with the exception of the slowest walking speed. The average increment in energy cost was 1·0% per 100-g increase in weight per pair of footwear. These results are similar to those reported for men from other studies which found increments in energy cost of 0·7 to 0·9% per 100-g increase in weight of footwear.     

The energy cost and heart-rate response of trained and untrained subjects walking and running in shoes and boots

Abstract

To determine the difference in the energy cost of walking and running in a lightweight athletic shoe and a heavier boot, fourteen male subjects (six trained and eight untrained) has their oxygen uptake ([Vdot]O₂) measured while walking and running on a treadmill. They wore each type of footwear, athletic shoes of the subjects' choice (average weight per pair = 616 g) and leather military boots (average weight per pair = 1776g), at three walking speeds (4·0, 5·6 and 7·3 km hour^?1) and three running speeds (8·9, 10·5 and 12·1 km hour^?1). The trials for running were repeated at the same three speeds with the subjects wearing shoes and these shoes plus lead weights. The weight of the shoes plus the lead weights was equal to the weight of the subjects' boots. The [Vdot]O₂values with boots were significantly (p < 0·05) higher (5·9?10·2%) at all speeds, except the slowest walk, 4·0 km hour^?1Also, [Vdot]O₂with shoes plus lead weights were significantly (p<0·05) higher than shoes alone. Weight alone appeared to account for 48-70% of the added energy cost of wearing boots. The relative energy cost ([Vdot]O₂, ml kg^?1?) of trained and untrained subjects were the same at all speeds. These data indicate that energy expenditure is increased by wearing boots. A large portion of this increase may be attributed to weight of footwear. In addition, the increased energy cost of locomotion with boots appears to place a limiting stress on untrained subjects.     

Effects of dynamic,static and combined work on heart rate and oxygen consumption

The effects upon heart rate and oxygen consumption of muscular exercises including simultaneous dynamic and static contractions were studied in three male subjects. Dynamic work consisted of walking at four speeds (0·56, 0·83, 1·11, 1·39 m s^?) on a horizontal treadmill; static work consisted of pushing against, pulling and holding 6, 9, 12, 18 and 24?kg; combined work associated walking with each one of the forms of static work. Physiological load is expressed in terms of cardiac cost (ΔHR) and oxygen cost (Δ[Vdot]_o2). The physiological cost of combined work increases with both the walking speed and the static load. For each parameter (HR and [Vdot]_o2) the extra-cost of combined work has been determined by computing the difference between the cost of combined work and the sum of the costs observed during static and dynamic exercises separately performed. The paired t-test shows significant differences for all of the walking-pushing tests, but only for 8 pulling tests and 2 holding tests. Linear relationships are observed between the oxygen extra-cost and load when walking at 0·56 or 0·83 ms^?1, with correlation coefficients statistically significant for pushing and pulling (p < 0·01) but not significant for holding tests. The present results show that, when the static work is combined with walking, the physiological response varies with the type of static work considered.     

The influence of flywheel weight and pedalling frequency on the biomechanics and physiological responses to bicycle exercise†

The physiological, subjective and biomechanical effects of altering flywheel weight and pedalling rate on a Quinton Model 870 bicycle ergometer were studied. Steel plates were added to the flywheel to increase its weight to 35·9 kg with a moment of inertia of 1·65 kg m². A 1·5 kg spoked wheel with a moment of inertia of 0·1 kg m² was used as the light flywheel. Eight subjects pedalled on two separate occasions for 6 min at 40, 50, 60, 70, 80 and 90 r.p.m. with workload levels representing 30 and 60% of their [Vdot]O₂max with each flywheel. Force plate pedals were used to measure the total resultant force on the pedals (F_R ) and the component perpendicular to the crank arm (F_T). A force effectiveness index (FEI) was denned as the average of F_T/F_R over a crank cycle. The result showed no statistically significant change (p<0·05) in [Vdot]O₂, heart rate and rating of perceived exertion of the FEI as a function of flywheel weight except for the [Vdot]O₂ at 50 r.p.m. for the light workload. As the r.p.m. increased from 40 to 90 r.p.m., the FEI decreased from 0·5 to 0·35 with the heavy load and from 0·36 to 0·22 with the light load. Measured physiological, subjective and biomechanical indices did not change significantly with flywheel weight. Increasing the pedalling rate caused a significantly less effective application of forces to the crank arm with only a small change in [Vdot]O₂.     

Effects of load carriage on heart rate,blood pressure and energy expenditure in children

Fifteen male primary school children, aged 10 years, were selected to carry school bags of 10, 15 and 20% of their own body weights, where 0% body weight was used as a control. Maximum oxygen uptake ([Vdot]O₂max) tests were conducted on a motorized treadmill using a continuous incremental protocol. During the load carrying test, subjects walked on a treadmill at 1.1 m s^?1 for 20 min at each load condition. Blood pressures were measured before, immediately following, and at 3 and 5 min after every trial. Heart rate and expired [Vdot]O₂ were recorded before, during and 5 min after walking using a cardiopulmonary function system. The results showed a significant difference in oxygen uptake, energy expenditure and the recovery of blood pressure rise for between 10 and 20% body weight load conditions. The carrying weight of a school bag for children could be recommended as 10% of body weight because it was not significantly different from 0% load in the metabolic cost.     

The metabolic cost of backpack and shoulder load carriage.

Eleven healthy male volunteer soldiers (mean [SD] age 24.0 [2.8] years, stature 174.1 [5.2] cm, body weight 73.2 [10.8] kg, body fat 14.2 [5.0]% and maximal oxygen uptake 4.1 [0.4] 1 min-1) walked at 4.8 km h-1 on a motor driven treadmill for 5 min at each of three gradients (0, 2.5 and 5%) whilst carrying a two-part 26 kg load either on each shoulder or strapped to a backpack frame. The load was made up of two cylinders, one weighing 18.4 kg and the other weighing 7.6 kg. For all treadmill gradients the mean (SD) backpacking heart rates and oxygen uptakes (0% gradient, 122 [10] beats min-1, 1.51 [0.11] 1 min-1; 2.5% gradient, 135 [10] beats min-1, 1.81 [0.13] 1 min-1; 5% gradient, 155 [7] beats min-1, 2.21 [0.11] 1 min-1) were significantly (p less than 0.001) lower than for shoulder load carriage (0% gradient, 130 [9] beats min-1, 1.70 [0.12] 1 min-1, 2.5% gradient, 147 [8] beats min-1; 2.01 [0.10] 1 min-1; 5% gradient 164 [9] beats min-1, 2.39 [0.11] 1 min-1). The relative oxygen cost of backpacking was 4.3-4.7% VO2 max lower than for shoulder load carriage. It is concluded that the metabolic cost of backpacking an asymmetric two part 26 kg load was significantly less than for shoulder load carriage when walking at 4.8 km h-1 on a treadmill over gradients of 0-5%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Energy expenditure and clearing snow: a comparison of shovel and snow pusher

In order to assess the energy demands of manual clearing of snow, nine men did snow clearing work for 15 min with a shovel and a snow pusher. The depth of the snowcover was 400–600 mm representing a very heavy snowfall. Heart rate (HR), oxygen consumption ([Vdot]O₂), pulmonary ventilation ( [Vdot]O_E), respiratory exchange ratio (R), and rating of perceived exertion (RPE) were determined during the work tasks. HR, [Vdot]O_E, R, and RPE were not significantly different between the shovel and snow pusher. HR averaged (± SD) 141 ± 20bmin_-1 with the shovel, and 142 ± 19 beats-min_-1 with the snow pusher. [Vdot]O₂was 2·1 ± 0·41 min_-1 (63 ± 12% [Vdot]O₂max) in shovelling and 2·6 ± 0·51 min_-1 (75 ± 14% [Vdot]O₂max) in snow pushing (p< 0·001). In conclusion manual clearing of snow in conditions representing heavy snowfalls was found to be strenuous physical work, not suitable for persons with cardiac risk factors, but which may serve as a mode of physical training in healthy adults.     

Metabolic and perceptual responses while carrying external loads on the head and by yoke

Abstract

The purpose of this study was to determine the metabolic efficiency and perceptual acceptability of transporting external loads on the head and by yoke. Ten young males (24·2 ±3·9 years) of average physical fitness ([Vdot]O_2max=49·8 ± 6·5ml kg^-1 min^-1) walked for 6min on a level motor-driven treadmill at 53·6, 73·8 and 93·9m min^-1. Subsequently, all subjects carried external loads (11·6, 16·1 and 20·6 kg) at the same speeds using the headpack (HP), transverse yoke (TY) and frontal yoke (FY) modes of load carriage. Measurements were obtained for oxygen uptake ([Vdot]O₂ l min^-1), local ratings of perceived exertion (RPE-L) and the overall perceived exertion (RPE-O). The [Vdot]O₂ was used in the computation of the metabolic efficiency ([Vdot]O₂ ml kg total weight^-1 min^-1).

Significant main effects (mode, load and speed) and three interaction effects (mode × load, mode × speed and load × speed) were obtained for metabolic efficiency. Scheffé post hoc analysis revealed that the metabolic efficiency for the TY and HP were greater than the FY while transporting the 16·1 and 20·6kg loads at all walking speeds (p <0·05). No significant loss in metabolic efficiency was found while carrying the 20·6kg load at 53·6 m min^-1. At 93·9 m min^-1, all external loads transported were associated with a loss in metabolic efficiency. The RPE-L for the HP was lower than the FY (p < 0·05). Both the RPE-0 and RPE-L increased as the walking speeds and external loads were increased. The findings suggest that load transportation using the FY system is both physiologically and perceptually unacceptable.     

Aerobic capacity of urban women homemakers in Bombay

Twenty-six healthy women homemakers residing in the metropolitan city of Bombay were studied on a treadmill and a cycle ergometer to determine their aerobic capacity ([Vdot]O₂ max) with a view to evaluating their cardio-respiratory fitness and ascertaining the job-demand-fitness-compatibility in household activities. The [Vdot]O₂ max was found to be significantly higher in treadmill experiments, i.e. 15% in absolute value and 18% in relative value, as compared with that obtained by cycle ergometry (p < 0·001). A much higher difference was observed in values derived from the two methods on the same subjects (i.e. 28% in absolute value and 31% in relative value). Thus, the [Vdot]O₂max obtained from treadmill experiments may be regarded as the maximal aerobic power or the highest oxygen uptake that an individual can attain during exercise, which in the sample of the present study was recorded as 1·901 min ^?1 (33·9 ml kg ^?1 min ^?1). The findings also revealed that age and body weight have a direct influence on [Vdot]O₂max, which was found to be significantly correlated, positively with the latter and negatively with the former (p<0·01 in both cases). The physiological job-demand of household activities seems to be compatible in relation to the [Vdot]O₂max of the homemakers.     

The Aerobic and Anaerobic Components of Work during Submaximal Exercise on a Bicycle Ergometer

Abstract

Inter-subject variability of oxygen intake ([Vdot]O₂)n relation to the anaerobic component of work has been investigated intensely on two healthy subjects and extensively on two groups of young and older men during work on an upright, stationary bicycle ergometer.

Significant differences (p<0·001) in [Vdot]O₂ were shown to exist between the two groups of subjects and the healthy men at the higher work-loads which could not be eliminated entirely by correction for body weight. The residual variation of [Vdot]O₂ on work-load was shown to be a consequence of the variation of anaerobic component of exercise. During work on a bicycle ergometer at exercise above about 50% [Vdot] O₂ max this should be taken into account if a valid assessment of energy expenditure is to be made.     

Physiological factors affecting upper body aerobic exercise

This study examined the influence selected physiological measurements have upon peak oxygen uptake (peak [Vdot]O₂) elicited by upper body (arm crank) exercise employing crank rates of 30 and 70 r.p.m. Nine male volunteers completed: two maximal effort arm crank tests, one cycle exercise maximal aerobic power (AP) test, measurements of isokinetic elbow extension strength (ES), isometric grip strength (GS) and arm volume (AV). Partial correlation coefficients (R) were obtained from a multiple regression analysis. For the 30 r.p.m. protocol, peak [Vdot]O₂ was strongly related to AP (r=0·80; R = 0·51) and moderately related to ES (r=?0·41; R =?0·41) and GS (r=0·40; R = 0·30). For the 70 r.p.m. protocol, peak [Vdot]O₂ was found to be strongly related to AP (r=0·94; R=0·88). AV values were not found to have a marked influence on upper body peak [Vdot]O₂ at either crank rate. These data indicate that aerobic power for cycle exercise is the most important determinant of upper body aerobic exercise performance.     

ERGONOMICS RESEARCH SOCIETY THE SOCIETY'S LECTURE, 1964.

Eight male volnntours, aged 20 to 43 yr, participated in a 1 min run to exhaustion. Six of the subjects had experienced work on the treadmill and ran regularly during the year. By means of a preliminary rim a work load was selected for each subject which would produce exhaustion in 60 sec. The speed of the treadmill was 12.8 kph for all runs except one (14.5 kph) and grade varied from 10 to 20%. The warm up consisted of walking 5.6 kph at a 10% grade for min and preceded the rim by 3 or 5 min. Oxygen consumption ([Vdot]o₂), heart rate (HR), and respiration rate (f) were recorded every 15 sec during the run and during the first 30 sec of recovery. Thereafter, recovory measurements were made during progressively longer intervals for a total of 30 min. [Vdot]0₃, during the run with warm up (2.69± 0.39 L) was significantly greater (p<0.05) than without warm up (2.50±0.41 L). Recovory [Vdot]o₃ and total [Vdot]o₂ (run plus recovory) were not significantly different between the warm up and without warm up runs. The results were not different when net [Vdot]o₂ ([Vdot]o₂minus rest [Vdot]o₃) was compared. A significant increase in heart rate was achieved during rutis with warm up compared to no warm up. Respiration rates were also increased with warm up but not significantly. The conclusion was that under the conditions of this study, warm up is of energetic benefit in preparing for a short exhaustive run.     

Permissible loads based on energy expenditure measurements

The literature is reviewed and, based on this, it is suggested that the upper general tolerance limit over an 8-hour work day, consisting of mixed physical work, including handling operations, is approximately 30–35% [Vdot]O₂ max (on bicycle legwork or treadmill). Therefore, the individual tasks must be adjusted to a metabolic level not exceeding 30–35% [Vdot]O₂ max in the majority of the labour force or may be more realistic in specific groups within the labour force (young/ old, male/female). The following metabolic values are suggested (1 [Vdot]O₂ ): males <40 years: 0·7males>40 years: 0·6; females < 40 years: 0·6; females >40 years: 0·5. It is important to notice that even with a metabolic rate below 30–35% [Vdot]O₂ max it is possible that local overstrain and/ or fatigue in the back muscles during, for example, manual handling operations of long duration can occur     

Interrelationships of respiratory variables of coal miners during work

Abstract

The respiratory responses of expiratory volume ([Vdot] _E), respiratory frequency (f _R), oxygen consumption ([Vdot] O₂), and carbon dioxide elimination ( [Vdot]CO₂) were measured for coal miners while they were performing a variety of work tasks (walking, carrying, shovelling, cranking and running). Because of the difficulties in relating the respiratory variables to external work rate and a close dependence of the respiratory responses on metabolic activity, oxygen consumption was chosen as an independent variable in the predictors for pulmonary ventilation, respiration frequency, and carbon dioxide elimination. It was necessary to use nonlinear equations for [Vdot] _E and [Vdot]Co₂ owing to exercise hyperpnoea above the anaerobic threshold.f _R did not correlate well with [Vdot]O₂ or any of the other respiratory variables. The relationship between [Vdot]_E and [Vdot]CO₂ was linear.     

Aerobic Capacity of Steel Workers in India

Abstract

Seventy-six workers, aged 21–43 y. drawn from three major steel plants—two located in the eastern and one in the central region of India (referred to as Group A, Group B and Group C respectively)—were studied on the bicycle ergometer to determine their aerobic capacity ([Vdot]_O2max), Both the direct and indirect methods were employed, the direct one being used only in the case of the workers in Group C. The mean [Vdot]_O2max of these workers was found to be 42·6 cm³ kg^?1 with a standard error of ± 0·71 cm³ kg^?1 min^?1. The highest values were observed among the workers in Group B (mean 47·0± 1·35 (S.E.)cm³kg^?1 min^?1) who are ethnically distinct and have a high level of customary activity, and the lowest among workers in Group C (mean: 39·0±0·74(S.E.) cm³kg^?1 min^?1).

As expected, the [Vdot]_O2max was found to be correlated positively with body weight, and negatively with age in a multiple regression analysis. Furthermore, the active Group B has values for [Vdot]_O2max that are significantly higher than those for the other Groups, a difference that is not attributable to weight or age.     

Metabolic,cardiovascular and spinal strain of a representative fuel replenishment task

The metabolic, cardiovascular and spinal strain of a representative fuel replenishment task for a tank crew were assessed using nine military subjects wearing coveralls in a comfortable ambient climate. The task involved lifting 5 gal jerry cans (weighing 23·4?kg) from the ground to a height representing a tank deck (1·676 m) at a rate of two lifts per minute for 15 min. Oxygen uptake ([Vdot]O₂), minute ventilation ([Vdot]E), heart rate (HR) and intra-abdominal pressure (IAP) were monitored continuously. After 15 min of lifting the mean [Vdot]O₂ was 0·821 min^?1 (S.D. 0·18). This was 27% of the predicted [Vdot]O₂ max. The mean [Vdot]E was 21·81 min^?1 (S.D.4·1) and the HR was 111·3 beats min^?1 (S.D. 17·8). The mean peak IAP was 105·6?mmHg, with 56% of the peak IAPs exceeding 90?Hg. The mean intrasubject coefficient of variation was 10·7% (range 7·2–24·2). In a separate series of 20 consecutive bimanual straight arm vertical lifts of 10?kg at 15 s intervals, the mean intrasubject COV% was 7·2% (range 3·2–11·2%). The replenishment task was considered acceptable in terms of the metabolic and cardiovascular strain. In terms of spinal strain, there may be an unacceptable risk of back injury if the task was normally undertaken as part of a soldier's full-time occupation over many years     

The effect of aerodynamic handlebars on oxygen consumption while cycling at a constant speed

Abstract

In this study, the oxygen consumption ([Vdot]O₂) of bicycling was measured at a fixed speed (40 km·h^?1on level terrain, with normal and aerodynamic handlebars using a Douglas bag collection system. Eleven elite (USCF category I or 2) men cyclists age 24 to 40 years (X¯=28·5, SD±4·6) performed four consecutive (two with each bar in alternating order) steady state rides at 40 km· h^?1over a 4 km flat course (same direction each trial). Expired gases were collected in a 1501 Douglas bag attached to a following vehicle during the last 45 s (approx. 0·5 km) of each trial. A repeated measures analysis of variance revealed a significant (p<0·02) handlebar effect. Specifically, [Vdot]O₂was 2% lower under the aerodynamic handlebar treatment (X¯=4·26, SD±0·36 1 min^?1when compared with that of the normal handlebar treatment (X¯=4·34, SD±0·35 1 min^?1The results of this study demonstrate that the reported aerodynamic advantage of the aerodynamic handlebars produces a small but significant reduction in the [Vdot]O₂of bicycling at 40 km·h^?1     

Estimated aerobic performance and energy cost of severe exercise of 24 h duration

Abstract

The maximal aerobic performance ([Vdot]O₂max) and energy cost of running at various speeds of two ultra-distance athletes were measured in the laboratory on a motor driven treadmill and the results related to observations made during a 24 h race. The athletes finished 1st and 2nd in the event and covered distances of 251·46 km and 234·56 km respectively during the 24 h period. From the measurements in the laboratory it was calculated that the average speeds sustained by the athletes during the competition were equivalent to an O₂ cost of 36·4 ml kg^?1 min^?1 and 35·3 ml kg^?1 min^?1 which represented approximately 50% of their [Vdot]O₂max. During the race the winner expended an estimated 77,829 kJ (18.595 kcal) which is three times the highest recorded value in the most severe industrial work. By the nature of the activity this figure must be regarded as at or near the upper limit of sustainable energy expenditure by man during a complete uninterrupted 24 h circadian cycle.     

A new kayak ergometer based on wind resistance

Abstract

An ergometer for kayak paddlers has been developed and used for winter training, measurements of work capacity and maximal oxygen uptake ([Vdot]O₂ max). Force is transmitted from the paddle by means of a wire connected to a flywheel mounted with six 9 × 9cm blades. Resistance, therefore, is based on wind turbulence generated by the flywheel. The mechanical efficiency of the ergometer at 63% (range 48-77) of [Vdot]O₂ max was 17% (range 16-18) (n= 13). The [Vdot]O₂ max was similar during bicycling (median 4·9; range 4·4-5·4l/min), arm cranking (median 4·8; range 4·3-5·11/min), on-water rowing in a kayak (median 4·7; range 4·0-4·91/min) and during rowing the kayak ergometer (median 4·8; range 4·3-5·21/min), (n = 6, p> 0·05). Work capacity during a 5 min ‘all-out’ test was 272 W (range 253–304 W) on the kayak ergometer (n = 17). The use of the ergometer for training helped to increase the aerobic power during arm exercise of Danish paddlers. Before introduction of the ergometer (February 1986), their VO₂ max was 4·6 (range 3·8-5·2) 1/min while 12 months later, it was 50 (range 4·2–5·7) 1/min (n = 14, p < 0·01). The ergometer has thus been found.useful for training and evaluation of work capacity in kayak paddlers.     

Scheduling rest for consecutive light and heavy work loads under hot ambient conditions

Three male and three female heat-acclimated subjects participated in a series of five testing sessions aimed at validating a resting period which was assigned to follow work under warm-humid (T_db 36°C, T_wb 31°C) and hot-dry (T_db 50°C, T_wb 25°C) ambient conditions. Each working period consisted of 25 min of walking at 30% [Vdot]_o2max followed by five minutes of carrying a load uphill at 75% [Vdot]_o2max. The working period was based on the expected HR as it could be derived from: (1) the work-specific HR as determined from the linear relationship between % [Vdot]_o2max and HR; (2) the heat-induced increments in HR; and (3) the endurance limits imposed by the age-dependent HR_max. Each 30 min of work was followed by 30 min of rest either under the same ambient conditions as for the working period, or under neutral ambient conditions. Judged by the levelling off of HR and by setting the limits of the T_re rise to 38°C during the consecutive walking periods, only the resting under the neutral conditions proved adequate. The level of blood lactic acid was the same under all ambient conditions for each sex, but was higher for the males, who carried a load of 12 kg, as compared to 10 kg for the females.