Effect of load and speed on the energetic cost of human walking (original) (raw)
Related papers
Effects of Backpack Load and Trekking Poles on Energy Expenditure During Field Track Walking
Sports Medicine International Open
This study evaluates the effects of the use of backpack load and trekking poles on field track walking energy expenditure. Twenty male volunteer pole walkers (age: 22.70±2.89 years; body mass: 77.90±11.19 kg; height: 1.77±0.06 m; percentage of body fat: 14.6±6.0%) walked at a self-selected pace on a pedestrian field track over a period of more than six months. Each subject was examined at random based on four walking conditions: non-poles and non-load, with poles and non-load, non-poles and with load, with poles and with load. Heart rate, oxygen uptake and energy expenditure were continuously recorded by a portable telemetric system. Non-load walking speed was lower during walking with poles when compared with no poles (p≤0.05). Oxygen uptake, energy expenditure and heart rate varied significantly across different conditions. Our results suggest that the use of trekking poles does not influence energy expenditure when walking without an additional load, but it can have an effect dur...
In this study, we showed a way of reducing the metabolic cost of walking with a backpack using load distribution and dynamic load compensation, provided by a wearable upper body device. This device distributes the backpack load between the shoulders and the pelvis, senses the vertical motion of the pelvis, and provides gait synchronized compensatory forces to reduce the dynamic loads from a backpack. It was hypothesized that by reducing dynamic loads from a backpack during load carriage, the users gait and postural adaptation, muscular effort and metabolic cost would be reduced. This hypothesis was supported by biomechanical and physiological measurements on a group of young healthy subjects, as they walked on a treadmill under 4 different conditions: unloaded; with a backpack, loaded with 25% of their body weight, supported on the shoulders; with the same load distributed between the shoulders and the pelvis; and with dynamic load compensation in addition to load distribution. The results showed reductions in gait and postural adaptations, muscle activity, vertical and braking ground reaction forces, and metabolic cost while carrying the same backpack load with the device. We conclude that the device can potentially reduce the risk of musculoskeletal injuries and muscle fatigue associated with carrying heavy backpack loads while reducing the metabolic cost of loaded walking.
Scandinavian Journal of Medicine & Science in Sports, 2014
It has been observed that the optimal speed (OPT) of human walking is independent of load on level surfaces because of the unaltered trajectory of the center of mass and consequent conservation of the pendular mechanism. However, the role of the inverted pendulum mechanism that combines speed, load, and gradient during walking remains unknown. In the present study, 10 subjects walked on a treadmill, with and without loading (25% of the body mass), at different speeds and slopes (0%, +7%, and +15%). The three-dimensional motion and VO2 were simultaneously registered. The mechanical external and internal work and the cost of transport (C) changed with the speed and gradient, but the load only affected C. OPT decreased with increasing gradient, and the pendular mechanics (R) was modified mainly as a result of changes in speed and gradient. OPT and R were independent of the load in these gradients. Remarkably, R increased with increasing speed and decreased (to 30%) with an increasing gradient; moreover, R was independent of load. Therefore, the energy-saving strategy by the pendular mechanism persists, although at a diminished level, in loaded walking on gradients and partially explains the OPT in this condition.
Influence of muscle‐belly and tendon gearing on the energy cost of human walking
Scandinavian Journal of Medicine & Science in Sports, 2022
Walking is the most common locomotor task during daily life activities. It has been classically described by an inverted pendulum paradigm, where the potential and kinetic energies associated to the body center of mass (BCoM) are out of phase and continuously exchange (as in a pendulum-like motion), reducing the total mechanical energy oscillations over a stride. 1 In walking, the relationship between net energy cost (C net : the metabolic energy expended, above rest, to cover one unit distance) and speed can be empirically described by a quadratic
Journal of Neurophysiology
Human gait adaptation implies that the nervous system senses energetic cost, yet this signal is unknown. We tested the hypothesis that the blood gas receptors sense cost for gait optimization by controlling blood O2 and CO2 with step frequency as people walked. At the simulated energetic minimum, ventilation and perceived exertion were lowest, yet subjects preferred walking at their original frequency. This suggests that blood gas receptors are not critical for sensing cost during gait.
Humans do not generally walk at constant speed, except perhaps on a treadmill. Normal walking involves starting, stopping and changing speeds, in addition to roughly steady locomotion. Here, we measure the metabolic energy cost of walking when changing speed. Subjects (healthy adults) walked with oscillating speeds on a constant-speed treadmill, alternating between walking slower and faster than the treadmill belt, moving back and forth in the laboratory frame. The metabolic rate for oscillating-speed walking was significantly higher than that for constant-speed walking (6–20% cost increase for +0.13–0.27 m s 21 speed fluctuations). The metabolic rate increase was correlated with two models: a model based on kinetic energy fluctuations and an inverted pendulum walking model, optimized for oscillating-speed constraints. The cost of changing speeds may have behavioural implications: we predicted that the energy-optimal walking speed is lower for shorter distances. We measured preferred human walking speeds for different walking distances and found people preferred lower walking speeds for shorter distances as predicted. Further, analysing published daily walking-bout distributions, we estimate that the cost of changing speeds is 4–8% of daily walking energy budget.
From Food to Foot: The Energy and Carbon Flows of the Human Body at Walking and Cycling
Journal of energy and power technology, 2022
The carbon footprint of motorized transport modes per unit length traveled encompasses the unit share of the vehicle lifetime emissions, that of the transport infrastructure, and those of the motor energy, considered both from "well to tank" and from "tank to wheel". In the active modes of transport, i.e., walking and cycling, the counterpart of motor energy is human energy, which is associated with two kinds of carbon flows: the carbon footprint of food intake,-which we call the Food to Body component-and the carbon dioxide emissions of respiration-say the Body to Foot component. In this article, we provide a model in simple mathematical form to assess those carbon flows per unit length. It involves the modal speed in (i) the Metabolic Equivalent of the Task (MET) which gives rise to the energy and carbon flows, and (ii) the ratio of time spent to length travelled. The two influences of speed onto a modal carbon footprint combine in the net MET per unit length, with some compensation. The carbon footprint of food intake varies widely depending on the food diet of individuals. In a numerical study, the Food to Foot carbon emission of walking, cycling, e-scooter riding, and driving a car are estimated and compared to the rest of modal carbon footprint. Under conditions typical of France in the 2010s based on the average food diet and low carbon intensity of electricity, the inclusion of F2F in modal
BMJ, 2022
Objective To compare the rate of energy expenditure of low efficiency walking with high efficiency walking. Design Laboratory based experimental study. setting United States. ParticiPants 13 healthy adults (six women, seven men) with no known gait disorder, mean (±standard deviation) age 34.2±16.1 years, height 174.2±12.6 cm, weight 78.2±22.5 kg, and body mass index 25.6±6.0. interventiOn Participants performed three, five minute walking trials around an indoor 30 m course. The first trial consisted of walking at a freely chosen walking speed in the participant's usual style. The next two trials consisted of low efficiency walks in which participants were asked to duplicate the walks of Mr Teabag and Mr Putey (acted by John Cleese and Michael Palin, respectively) in the legendary Monty Python Ministry of Silly Walks (MoSW) skit that first aired in 1970. Distance covered during the five minute walks was used to calculate average speed. Ventilation and gas exchange were collected throughout to determine oxygen uptake (̇VO 2 ; mL O 2 /kg/min) and energy expenditure (EE; kcal/kg/min; 1 kcal=4.18 kJ), reported as mean±standard deviation. Main OutcOMe Measures ̇VO 2 and EE. results ̇VO 2 and EE were about 2.5 times higher (P<0.001) during the Teabag walk compared with participants' usual walk (27.9±4.8 v 11.3±1.9 mL O 2 /kg/min; 0.14±0.03 v 0.06±0.01 kcal/kg/min), but were not different during the Putey walk (12.3±1.8 mL/kg/ min; 0.06±0.01 kcal/kg/min). Each minute of Teabag walking increased EE over participants' usual walking by an average of 8.0 kcal (range 5.5-12.0) in men and by 5.2 kcal (range 3.9-6.2) in women, and qualified as vigorous intensity physical activity (>6 resting metabolic equivalents). cOnclusiOns For adults with no known gait disorder who average approximately 5000 steps/day, exchanging about 22%-34% of their daily steps with higher energy, low efficiency walking in Teabag style-requiring around 12-19 min-could increase daily EE by 100 kcal. Adults could achieve 75 minutes of vigorous intensity physical activity per week by walking inefficiently for about 11 min/day. Had an initiative to promote inefficient movement been adopted in the early 1970s, we might now be living among a healthier society. Efforts to promote higher energyand perhaps more joyful-walking should ensure inclusivity and inefficiency for all.