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Schram B, Orr R, Niederberger B, Givens A, Bernards J, Kelly KR. Cardiovascular Demand Differences Between Male and Female US Marine Recruits During Progressive Loaded Hikes. J Strength Cond Res 2024; 38:e454-e458. [PMID: 38683971 PMCID: PMC11286159 DOI: 10.1519/jsc.0000000000004816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
ABSTRACT Schram, B, Orr, R, Niederberger, B, Givens, A, Bernards, J, and Kelly, KR. Cardiovascular demand differences between male and female US Marine recruits during progressive loaded hikes. J Strength Cond Res 38(8): e454-e458, 2024-Despite having to carry the same occupational load, female soldiers tend to be lighter than male soldiers. The aim of this study was to determine the differences in cardiovascular load between female and male US Marine recruits during progressive load carriage hikes. United States Marine Corps recruits (565 male recruits; 364 female recruits) completed 6 loaded hikes over 6 weeks (1: 10 kg, 30 minutes; 2: 10 kg, 45 minutes; 3: 15 kg, 30 minutes, 4: 15 kg, 45 minutes; 5: 20 kg, 30 minutes; 6: 20 kg, 45 minutes) during which cardiovascular response was measured. Average heart rate (HRavg), HR maximum (HRmax), and pace were measured via a wrist-worn physiological monitor. Independent sample t -tests were conducted to compare between sexes, with significance set at 0.008 after adjusting for multiple comparisons. The average female recruit had significantly lower body mass (BM) compared with the average male recruit ( p < 0.001) and thus carried a significantly heavier relative load. (10 kg ∼17%, 15 kg ∼25%, 20 kg ∼33%, p < 0.001). There were no significant differences in pace in any hike, and no significant differences were found in HRavg or HRmax when comparing female and male Marines during Hike 1. For female Marines, HRavg was significantly higher compared with male Marines during Hike 2 (+6.5 b·min -1 , p < 0.001) and Hike 3 (+7.4 b·min -1 , p < 0.001), and both HRavg and HRmax were significantly higher in Hike 4 (+11.9 b·min -1 , +8.4 b·min -1 , p < 0.001), Hike 5 (+7.7 b·min -1 , +7.9 b·min -1 , p < 0.001), and Hike 6 (+6.9 b·min -1 , +7.1 b·min -1 , p < 0.001), respectively. Female Marines endured greater cardiovascular demand compared with male Marines during load carriage events when carrying loads greater than 15 kg (∼25% BM).
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Affiliation(s)
- Ben Schram
- Tactical Research Unit, Bond University, Robina, QLD, Australia
| | - Robin Orr
- Tactical Research Unit, Bond University, Robina, QLD, Australia
| | - Brenda Niederberger
- Warfighter Performance Department, Naval Health Research Center, San Diego, California; and
- Leidos, Inc., San Diego, California
| | - Andrea Givens
- Warfighter Performance Department, Naval Health Research Center, San Diego, California; and
- Leidos, Inc., San Diego, California
| | - Jake Bernards
- Warfighter Performance Department, Naval Health Research Center, San Diego, California; and
- Leidos, Inc., San Diego, California
| | - Karen R. Kelly
- Warfighter Performance Department, Naval Health Research Center, San Diego, California; and
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Slattery P, Cofré Lizama LE, Wheat J, Gastin P, Dascombe B, Middleton K. The Agreement between Wearable Sensors and Force Plates for the Analysis of Stride Time Variability. SENSORS (BASEL, SWITZERLAND) 2024; 24:3378. [PMID: 38894183 PMCID: PMC11174954 DOI: 10.3390/s24113378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/14/2024] [Accepted: 05/21/2024] [Indexed: 06/21/2024]
Abstract
The variability and regularity of stride time may help identify individuals at a greater risk of injury during military load carriage. Wearable sensors could provide a cost-effective, portable solution for recording these measures, but establishing their validity is necessary. This study aimed to determine the agreement of several measures of stride time variability across five wearable sensors (Opal APDM, Vicon Blue Trident, Axivity, Plantiga, Xsens DOT) and force plates during military load carriage. Nineteen Australian Army trainee soldiers (age: 24.8 ± 5.3 years, height: 1.77 ± 0.09 m, body mass: 79.5 ± 15.2 kg, service: 1.7 ± 1.7 years) completed three 12-min walking trials on an instrumented treadmill at 5.5 km/h, carrying 23 kg of an external load. Simultaneously, 512 stride time intervals were identified from treadmill-embedded force plates and each sensor where linear (standard deviation and coefficient of variation) and non-linear (detrended fluctuation analysis and sample entropy) measures were obtained. Sensor and force plate agreement was evaluated using Pearson's r and intraclass correlation coefficients. All sensors had at least moderate agreement (ICC > 0.5) and a strong positive correlation (r > 0.5). These results suggest wearable devices could be employed to quantify linear and non-linear measures of stride time variability during military load carriage.
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Affiliation(s)
- Patrick Slattery
- Sport, Performance and Nutrition Research Group, School of Allied Health, Human Services and Sport, La Trobe University, Melbourne, VIC 3083, Australia; (P.S.); (L.E.C.L.); (P.G.)
| | - L. Eduardo Cofré Lizama
- Sport, Performance and Nutrition Research Group, School of Allied Health, Human Services and Sport, La Trobe University, Melbourne, VIC 3083, Australia; (P.S.); (L.E.C.L.); (P.G.)
- Department of Nursing and Allied Health, School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
- Department of Medicine, The University of Melbourne, Parkville, VIC 3050, Australia
| | - Jon Wheat
- Academy of Sport and Physical Activity, Sheffield Hallam University, Sheffield S10 2DN, UK;
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK
| | - Paul Gastin
- Sport, Performance and Nutrition Research Group, School of Allied Health, Human Services and Sport, La Trobe University, Melbourne, VIC 3083, Australia; (P.S.); (L.E.C.L.); (P.G.)
| | - Ben Dascombe
- Applied Sport Science and Exercise Testing Laboratory, School of Life and Environmental Sciences, University of Newcastle, Ourimbah, NSW 2258, Australia;
- Sports and Exercise Science, School of Health Sciences, Western Sydney University, Sydney, NSW 2000, Australia
| | - Kane Middleton
- Sport, Performance and Nutrition Research Group, School of Allied Health, Human Services and Sport, La Trobe University, Melbourne, VIC 3083, Australia; (P.S.); (L.E.C.L.); (P.G.)
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Thivel D, Ennequin G, Lambert C, Siroux J, Ratel S, Boscaro A, Pelissier L, Julian V, Cardenoux C, Duclos M, Lazzer S, Pereira B, Boirie Y, Isacco L. Improved walking energy efficiency might persist in presence of simulated full weight regain after multidisciplinary weight loss in adolescents with obesity: the POWELL study. Int J Obes (Lond) 2024; 48:384-393. [PMID: 38052874 DOI: 10.1038/s41366-023-01427-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 11/03/2023] [Accepted: 11/23/2023] [Indexed: 12/07/2023]
Abstract
AIM Weight loss leads to a reduction of the energy cost of walking but the respective implications of the metabolic and mechanic changes remain unknown. The present study compares the post-weight loss energy cost of walking (Cw) with and without a total reload of the induced weight reduction in adolescents with obesity. METHODS Energy cost of walking and substrate use were evaluated during a graded walking exercise (4×6-min at 0.75, 1, 1.25, 1.5 m.s-1) before (V1) and after a 12-week intervention in 21 adolescents with obesity (11 girls; 13.8 ± 1.4 y). After weight loss, the walking exercise was randomly repeated once without weight reload (V2) and once with a loading corresponding to the total induced weight loss during the program (V2L). Body composition was assessed before and after the intervention. RESULTS Body weight and fat mass decreased in response to the 12-week intervention (p < 0.001), while FFM did not change. The absolute gross Cw (ml.m-1) was higher on V1 compared with V2 at every speed. The absolute net Cw (ml.m-1) was higher on V1 compared to V2L at 0.75 m.s-1 (p = 0.04) and 1 m.s-1 (p = 0.02) and higher on V2L compared with V2 at 1.5 m.s-1 (p = 0.03). Net Cw (ml.m-1.kg-1) on V1 being higher than V2 (p < 0.001), and V2L higher than V2 (p = 0.006). The absolute CHO oxidation (mg.min-1) did not show any condition effect (p = 0.12) while fat utilization was higher on V1 compared to V2 and V2L (p < 0.001). Relative to body weight CHO oxidation was lower on V1 compared to V2 (p = 0.04) and V2L (p = 0.004) while relative to body weight fat oxidation was higher on V1 than V2 (p = 0.002). CONCLUSION Adolescents with obesity might not show an entire rise back to pre-weight loss values of their metabolic cost of walking when weight gain is simulated. These new findings suggest metabolic and physiological adaptations to weight loss of the energy metabolism that remain to be clarified.
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Affiliation(s)
- D Thivel
- Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont Auvergne University, 63000, Clermont-Ferrand, France.
- International Research Chair Health in Motion, Clermont Auvergne University Foundation, 63000, Clermont-Ferrand, France.
| | - G Ennequin
- Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont Auvergne University, 63000, Clermont-Ferrand, France
- International Research Chair Health in Motion, Clermont Auvergne University Foundation, 63000, Clermont-Ferrand, France
| | - C Lambert
- Biostatistics Unit, DRCI, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France
| | - J Siroux
- Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont Auvergne University, 63000, Clermont-Ferrand, France
| | - S Ratel
- Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont Auvergne University, 63000, Clermont-Ferrand, France
| | - A Boscaro
- Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont Auvergne University, 63000, Clermont-Ferrand, France
| | - L Pelissier
- Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont Auvergne University, 63000, Clermont-Ferrand, France
| | - V Julian
- CHU Clermont-Ferrand, Clermont-Ferrand, France; Department of Sport Medicine and Functional and Respiratory Rehabilitation, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France
| | - C Cardenoux
- Children Medical Center, 63450, Romagnat, France
| | - M Duclos
- International Research Chair Health in Motion, Clermont Auvergne University Foundation, 63000, Clermont-Ferrand, France
- CHU Clermont-Ferrand, Clermont-Ferrand, France; Department of Sport Medicine and Functional and Respiratory Rehabilitation, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France
| | - S Lazzer
- Department of Medicine, School of Sport Sciences, University of Udine, 33058, Udine, Italy
| | - B Pereira
- Biostatistics Unit, DRCI, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France
| | - Y Boirie
- CSO-CALORIS, CHU Clermont-Ferrand, 63000 Clermont-Ferrand, France; Department of Human Nutrition, CHU Clermont-Ferrand, 63000, Clermont-Ferrand, France
| | - L Isacco
- Laboratory of the Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), Clermont Auvergne University, 63000, Clermont-Ferrand, France
- International Research Chair Health in Motion, Clermont Auvergne University Foundation, 63000, Clermont-Ferrand, France
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Wheelock CE, Stooks J, Schwob J, Hostler D. Continuous rise in oxygen consumption during prolonged military loaded march in the heat with and without fluid replacement: a pilot study. BMJ Mil Health 2024:e002573. [PMID: 38373790 DOI: 10.1136/military-2023-002573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 02/02/2024] [Indexed: 02/21/2024]
Abstract
INTRODUCTION V̇O2 drift, the rise in oxygen consumption during continuous exercise, has not been adequately reported during prolonged military marches. The purpose of this study was to analyse V̇O2 and energy expenditure (EE) during a loaded march with and without rehydration efforts. Second, the study aimed to compare EE throughout the march with predicted values using a validated model. METHODS Seven healthy men (23±2 years; V̇O2max: 50.8±5.3 mL/kg/min) completed four 60 min loaded marches (20.4 kg at 50% V̇O2max) in a warm environment (30°C and 50% relative humidity). Three were preceded by hypohydration via a 4-hour cold water immersion (18°C). The control (CON) visit was a non-immersed euhydrated march. After water immersion, subjects were rehydrated with 0% (NO), 50% (HALF) or 100% (FULL) of total body mass lost. During exercise, V̇O2 and EE were collected and core temperature change was calculated. To determine if EE could be accurately predicted, values were compared with a calculated estimate using the US Army Load Carry Decision Aid (LCDA). RESULTS At the start of exercise, there was no difference between conditions in V̇O2 (ALL: 24.3±0.3 mL/kg/min; p=0.50) or EE (ALL: 8.6±1.0 W/kg; p=0.68). V̇O2 (p=0.02) and EE (p<0.01) increased during exercise and were 12.3±10.0% and 12.8±9.5% greater, respectively, at 60 min across all trials and were not mitigated by rehydration amount. There was an effect of core temperature change on V̇O2 for each condition (CON: r=0.62; NO: r=0.47; HALF: r=0.70; FULL: r=0.55). LCDA-predicted values were different from measured EE during exercise. CONCLUSION V̇O2 drift occurred during loaded military marches and was associated with increases in EE and core temperature change. Pre-exercise hypohydration with water immersion followed by rehydration did not influence the degree of drift. LCDA prediction of EE may not agree with measured values during prolonged loaded marches where V̇O2 drift occurs.
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Affiliation(s)
| | - J Stooks
- Exercise and Nutrition Sciences, SUNY Buffalo, Buffalo, New York, USA
| | - J Schwob
- Exercise and Nutrition Sciences, SUNY Buffalo, Buffalo, New York, USA
| | - D Hostler
- Exercise and Nutrition Sciences, SUNY Buffalo, Buffalo, New York, USA
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Prado-Nóvoa O, Rodríguez J, Zorrilla-Revilla G, Vidal-Cordasco M, Mateos A. Evaluating the human capacity of carrying loads without costs: A scoping review of the Free-Ride phenomenon. Am J Hum Biol 2022; 34:e23794. [PMID: 36056617 DOI: 10.1002/ajhb.23794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 01/25/2023] Open
Abstract
OBJECTIVES Several researchers have obtained discordant results testing the human capability to transport loads without added locomotion costs. Carrying loads has an extended relevance to human ecology, thus a review of the Free-Ride phenomenon detection according to the existing literature is needed. METHOD A search was made in November 2021 in SCOPUS, Google Scholar, and Web of Science to identify studies comparing the energy expenditure of loaded and unloaded locomotion. Descriptive percentages were calculated with the data obtained from each study, and a Chi-squared (χ2 ) independency test and a contingency table were applied to observe the relationship between sample characteristics, experimental procedures, and the detection of the Free-Ride. RESULTS A total of 45 studies met the inclusion criteria. Eighty two percent do not detect the Free-Ride phenomenon. The general detection is independent of sex, experience, load position, load size, and speed (p value >.05) although the papers detecting the Free-Ride have some common characteristics. CONCLUSION The literature does not support a Free-Ride capacity, but future research testing this phenomenon should consider the load size, the load position, the level of expertise, or the speed. As the Free-Ride is not generalizable, it can be hypothesized that other mechanisms may have emerged during human evolution to buffer the energetic demands of load carrying.
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Affiliation(s)
- Olalla Prado-Nóvoa
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK
| | - Jesús Rodríguez
- National Research Center on Human Evolution (CENIEH), Burgos, Spain
| | | | - Marco Vidal-Cordasco
- EvoAdapta Research group, Department of Historical Sciences, University of Cantabria, Santander, Spain
| | - Ana Mateos
- National Research Center on Human Evolution (CENIEH), Burgos, Spain
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Nonlinear Analyses Distinguish Load Carriage Dynamics in Walking and Standing: A Systematic Review. J Appl Biomech 2022; 38:434-447. [PMID: 36170973 DOI: 10.1123/jab.2022-0062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 08/08/2022] [Accepted: 08/15/2022] [Indexed: 11/18/2022]
Abstract
Load carriage experiments are typically performed from a linear perspective that assumes that movement variability is equivalent to error or noise in the neuromuscular system. A complimentary, nonlinear perspective that treats variability as the object of study has generated important results in movement science outside load carriage settings. To date, no systematic review has yet been conducted to understand how load carriage dynamics change from a nonlinear perspective. The goal of this systematic review is to fill that need. Relevant literature was extracted and reviewed for general trends involving nonlinear perspectives on load carriage. Nonlinear analyses that were used in the reviewed studies included sample, multiscale, and approximate entropy; the Lyapunov exponent; fractal analysis; and relative phase. In general, nonlinear tools successfully distinguish between unloaded and loaded conditions in standing and walking, although not in a consistent manner. The Lyapunov exponent and entropy were the most used nonlinear methods. Two noteworthy findings are that entropy in quiet standing studies tends to decrease, whereas the Lyapunov exponent in walking studies tends to increase, both due to added load. Thus, nonlinear analyses reveal altered load carriage dynamics, demonstrating promise in applying a nonlinear perspective to load carriage while also underscoring the need for more research.
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Impact of Backpacks on Ergonomics: Biomechanical and Physiological Effects: A Narrative Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116737. [PMID: 35682317 PMCID: PMC9180465 DOI: 10.3390/ijerph19116737] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/20/2022] [Accepted: 05/25/2022] [Indexed: 11/24/2022]
Abstract
(1) Background: the effects of load carriage packs on human gait biomechanics, physiology and metabolism depend on the weight carried, the design of the pack and its interaction with the user. (2) Methods: An extensive search in the PubMed database was performed to find all the relevant articles using the following keywords: backpack, rucksack, backpack ergonomy and sports backpack; 60 articles were included. (3) Results and significance: Double pack (DP) and T-pack (TP) designs are recommended solutions for school children, compared with backpacks (BP). For soldiers and hikers, a backpack remains the best compromise. A hip belt is recommended for BPs as well as for the back of DPs. Shorter and stiffer shoulder straps combined with a higher and tighter load placement on the back provide the best combination in terms of balance, muscle activation and energy expenditure. It is, therefore, possible to determine guidelines for designing the optimal load carriage system, depending on the application. (4) Conclusions: based on the available evidence, DP and TP are advantageous in terms of posture. DP is better than conventional BPs in terms of balance and muscle activation, but has the disadvantage of limited visibility, thermal sensation and obstructed ventilation. In general, it is desirable not to exceed 40% of body mass (BM).
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James S, Damian C, Mathew B. Energy cost and knee extensor strength changes following multiple day military load carriage. APPLIED ERGONOMICS 2021; 97:103503. [PMID: 34237588 DOI: 10.1016/j.apergo.2021.103503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
Military exercises and recruit training requires soldiers, including new recruits, to undergo multiple days of substantial physical stress. The aim of this study was to evaluate the physiological impact of multiple days of military load carriage by addressing the hypothesis: A second day of load carriage increases oxygen uptake and reduces knee extensor torque compared to a single day of load carriage. A load carriage group (n = 12) (carrying 32 kg) and unloaded group (n = 14) walked on a treadmill for 2 h on two consecutive days. Knee extensor and flexor torque were assessed by dynamometry at speeds of: 0°·s-1,60°·s-1 and 180°·s-1 before and after load carriage on day one and two, and 24 h following day 2. Oxygen uptake was assessed via respiratory gas assessment at the 6th and 119th minute of load carriage on day one and two. When assessed by mixed methods ANOVA (alpha: 0.05), an interaction effect was observed for oxygen uptake (p < 0.001), with post hoc assessment highlighting second day of load carriage significantly increased oxygen uptake compared to day one post in the loaded group (28.9(3.0) vs 25.8(3.4), p = 0.048). An interaction effect was observed for all knee extensor variables (all p < 0.05). All knee extensor peak torque variables were significantly associated to oxygen uptake at 0°s-1 (r = -0.576, p < 0.05), 60°s-1 (r = -0.552, p < 0.05), and 180°s-1 (r = -0.589, p < 0.05). Two days of load carriage significantly increases oxygen uptake and reduces knee extensor and flexor torque compared to a single day of load carriage. Subsequently, physical training programmes aimed at increasing knee extensor strength may protect against increases in oxygen uptake.
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Affiliation(s)
- Scales James
- Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1QU, UK.
| | - Coleman Damian
- Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1QU, UK
| | - Brown Mathew
- Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1QU, UK
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The Added Value of Musculoskeletal Simulation for the Study of Physical Performance in Military Tasks. SENSORS 2021; 21:s21165588. [PMID: 34451033 PMCID: PMC8402289 DOI: 10.3390/s21165588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/03/2021] [Accepted: 08/16/2021] [Indexed: 11/16/2022]
Abstract
The performance of military tasks is often exacerbated by additional load carriage, leading to increased physical demand. Previous studies showed that load carriage may lead to increased risk of developing musculoskeletal injuries, a reduction in task speed and mobility, and overall performance degradation. However, these studies were limited to a non-ambulatory setting, and the underlying causes of performance degradation remain unclear. To obtain insights into the underlying mechanisms of reduced physical performance during load-carrying military activities, this study proposes a combination of IMUs and musculoskeletal modeling. Motion data of military subjects was captured using an Xsens suit during the performance of an agility run under three different load-carrying conditions (no load, 16 kg, and 31 kg). The physical performance of one subject was assessed by means of inertial motion-capture driven musculoskeletal analysis. Our results showed that increased load carriage led to an increase in metabolic power and energy, changes in muscle parameters, a significant increase in completion time and heart rate, and changes in kinematic parameters. Despite the exploratory nature of this study, the proposed approach seems promising to obtain insight into the underlying mechanisms that result in performance degradation during load-carrying military activities.
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Fumery G, Turpin NA, Claverie L, Fourcassié V, Moretto P. A biomechanical study of load carriage by two paired subjects in response to increased load mass. Sci Rep 2021; 11:4346. [PMID: 33623094 PMCID: PMC7902643 DOI: 10.1038/s41598-021-83760-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 02/02/2021] [Indexed: 01/31/2023] Open
Abstract
The biomechanics of load carriage has been studied extensively with regards to single individuals, yet not so much with regards to collective transport. We investigated the biomechanics of walking in 10 paired individuals carrying a load that represented 20%, 30%, or 40% of the aggregated body-masses. We computed the energy recovery rate at the center of mass of the system consisting of the two individuals plus the carried load in order to test to what extent the pendulum-like behavior and the economy of the gait were affected. Joint torque was also computed to investigate the intra- and inter-subject strategies occurring in response to this. The ability of the subjects to move the whole system like a pendulum appeared rendered obvious through shortened step length and lowered vertical displacements at the center of mass of the system, while energy recovery rate and total mechanical energy remained constant. In parallel, an asymmetry of joint moment vertical amplitude and coupling among individuals in all pairs suggested the emergence of a leader/follower schema. Beyond the 30% threshold of increased load mass, the constraints at the joint level were balanced among individuals leading to a degraded pendulum-like behavior.
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Affiliation(s)
- Guillaume Fumery
- grid.508721.9Centre de Recherches Sur La Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CRCA, UMR CNRS-UPS 5169, 118 Route de Narbonne, 31062 Toulouse, France ,Physical Medicine and Rehabilitation Center, MAS Marquiol, Toulouse, France
| | - Nicolas A. Turpin
- IRISSE Lab (EA 4075), UFR SHE, Sport Sciences Department (STAPS), Université de La Réunion, 117, rue du général Ailleret, 97430 le Tampon, France
| | - Laetitia Claverie
- grid.508721.9Centre de Recherches Sur La Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CRCA, UMR CNRS-UPS 5169, 118 Route de Narbonne, 31062 Toulouse, France
| | - Vincent Fourcassié
- grid.508721.9Centre de Recherches Sur La Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CRCA, UMR CNRS-UPS 5169, 118 Route de Narbonne, 31062 Toulouse, France
| | - Pierre Moretto
- grid.508721.9Centre de Recherches Sur La Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CRCA, UMR CNRS-UPS 5169, 118 Route de Narbonne, 31062 Toulouse, France
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Zwingmann L, Below T, Braun H, Wahl P, Goldmann JP. Consequences of police-related personal protective equipment and physical training status on thermoregulation and exercise energy expenditure. J Sports Med Phys Fitness 2021; 62:1137-1146. [PMID: 33619952 DOI: 10.23736/s0022-4707.21.12196-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND The aim was to examine the impact of personal protective equipment (PPE) on human thermoregulation and its alteration in groups of different training status. METHODS 45 men performed a maximum voluntary contraction test in an upright pull position to determine lower body strength and a graded treadmill test to determine maximum oxygen uptake (VO2max). Body composition was estimated via bioelectric impedance analysis. According to specific cutoff values, participants were assigned to a group of endurance-trained, strength-trained, endurance- and strength-trained, or untrained individuals. Subsequently, they completed two graded exercise tests until volitional exhaustion, once wearing sports wear (SPW) and once wearing PPE (20.9 kg). Participants were weighed before and afterward to investigate sweat loss and sweat rate. Body temperature was measured continuously from the tympanic membrane. Energy expenditure was derived from breathing gas analysis. RESULTS Sweat rate was 91% higher in PPE than in SPW but not significantly differnt between groups (p > 0.05). Body temperature was significantly higher in PPE during submaximal (+1.14 ± 0.45 °C) and maximal exercise intensity (+0.68 ± 0.57 °C) and was poorely related to VO2max and body composition. Energy expenditure significantly differed between both garments (+37% in PPE) and groups (p < 0.05). Additionally, energy expenditure significantly correlated with body weight (r = 0.84 in SPW and r = 0.68 in PPE). CONCLUSIONS Strength training alone does not seem to have any or negligible effects on thermoregulation. Endurance training and weight management might lead to rather small improvements in heat tolerance.
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Affiliation(s)
- Lukas Zwingmann
- Department of Molecular and Cellular Sport Medicine, Institute of Cardiology and Sports Medicine, German Sport University Cologne, Cologne, Germany - .,The German Research Centre of Elite Sport Cologne, German Sport University Cologne, Cologne, Germany -
| | - Tim Below
- The German Research Centre of Elite Sport Cologne, German Sport University Cologne, Cologne, Germany
| | - Hans Braun
- The German Research Centre of Elite Sport Cologne, German Sport University Cologne, Cologne, Germany.,Institute of Biochemistry German Sport University Cologne, Cologne, Germany
| | - Patrick Wahl
- Department of Molecular and Cellular Sport Medicine, Institute of Cardiology and Sports Medicine, German Sport University Cologne, Cologne, Germany.,The German Research Centre of Elite Sport Cologne, German Sport University Cologne, Cologne, Germany
| | - Jan-Peter Goldmann
- The German Research Centre of Elite Sport Cologne, German Sport University Cologne, Cologne, Germany.,Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany
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12
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Wang Z, Atakan MM, Yan X, Turnagöl HH, Duan H, Peng L. Graded exercise test with or without load carriage similarly measures maximal oxygen uptake in young males and females. PLoS One 2021; 16:e0246303. [PMID: 33524068 PMCID: PMC7850508 DOI: 10.1371/journal.pone.0246303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/18/2021] [Indexed: 11/29/2022] Open
Abstract
The aim of this was to compare the effects of the graded exercise test (GXT) with or without load carriage on maximal oxygen uptake ([Formula: see text]) heart rate (HR), and expired ventilation ([Formula: see text]) and blood lactate in young healthy males and females. The study included ten females (age:20.2±0.7 yrs) and ten males (age:19.5±0.7 yrs) who performed the modified Bruce protocol at five load conditions; unloaded, 5, 10, 15, and 20% of body weight (BW) (kg). All the tests were performed in random order, at least 48 hours apart. During the GXTs, HR, [Formula: see text], [Formula: see text], workload and test duration were recorded and blood lactate concentration was measured before and immediately after the GXTs. [Formula: see text] remained unchanged during the GXTs in load and unloaded conditions for both sexes (p>0.05). Test duration was significantly less in females during the GXT with 15% BW (15.9±0.51 min vs. 18.1±1.14 min; p = 0.014) and 20% BW load carriage (15.2±0.75 min vs. 18.1±1.14 min; p = 0.020), compared to the unloaded GXT. Males showed significant decrease in the test duration during the GXT with load 15% BW (20.5±0.53 min vs. 22.8±0.61 min; p = 0.047) and with 20% BW (19.6±0.42 min vs. 22.8±0.71 min; p = 0.004), compared to the GXT with 5% BW. [Formula: see text] statistically decreased in female subjects only at 15% BW compared to 20% BW (15% BW = 77.9 ± 10.5 L/min vs. 15% BW = 72.0 ± 10.9 L/min; p = 0.045). There was no difference observed in maximal HR and blood lactate concentration between the GXTs in load and unloaded conditions. This study indicates that no matter the load % used during the GXT, [Formula: see text], but not total exercise time, remains the same in young males and females.
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Affiliation(s)
- Zhenhuan Wang
- Key Lab of General Administration of Sport, Southwest University, Chongqing, China
- Institute for Health and Sport, Victoria University, Footscray, Melbourne, Australia
| | - Muhammed M. Atakan
- Institute for Health and Sport, Victoria University, Footscray, Melbourne, Australia
- Division of Nutrition and Metabolism in Exercise, Faculty of Sport Sciences, Hacettepe University, Ankara, Turkey
| | - Xu Yan
- Institute for Health and Sport, Victoria University, Footscray, Melbourne, Australia
- College of Health and Biomedicine, Victoria University, Melbourne, Australia
| | - Hüseyin H. Turnagöl
- Division of Nutrition and Metabolism in Exercise, Faculty of Sport Sciences, Hacettepe University, Ankara, Turkey
| | - Honglei Duan
- Key Lab of General Administration of Sport, Southwest University, Chongqing, China
| | - Li Peng
- Key Lab of General Administration of Sport, Southwest University, Chongqing, China
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13
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Pace MT, Green JM, Killen LG, Swain JC, Chander H, Simpson JD, O'Neal EK. Minimalist style boot improves running but not walking economy in trained men. ERGONOMICS 2020; 63:1329-1335. [PMID: 32588761 DOI: 10.1080/00140139.2020.1778096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
This study examined movement economy under load with 1000 g minimalist (MIN) vs. 1600 g traditional (TRD) style boots. Fourteen trained, male participants completed a VO2peak test (46.6 ± 7.3 ml/kg/min) while wearing a 16 kg external load. Treadmill speeds for the running economy (RE) trials were determined by the slowest pace in which participants completed a full stage with a running gait pattern during the VO2peak test. Walking economy (WE) pace was 1.6 km/h slower than RE pace. During the second session, participants completed 5-min exercise bouts at WE and RE pace under load wearing MIN and TRD. There were no differences for any measured variables during WE trials. In contrast, RE (MIN = 2.95 ± 0.28 vs. TRD = 3.04 ± 0.30 L/min; p = .003: Cohen's d = 0.32), respiratory exchange ratio (p < .001), and perceptual measures (p < .05) were all improved while wearing MIN. Practitioner summary: In trained men, 1000 g/pair minimalist style boots (MIN) resulted in improvements of approximately 3% and 5% for running economy and respiratory exchange ratio versus 1600 g/pair traditional boots while wearing a 16 kg kit. Perceptual responses, including comfort, also favoured MIN. These effects were not found at walking pace. Abbreviations: MIN: minimalist style boots; TRD: traditional style boots; RE: running economy; WE: walking economy; ES: effect size; RER: respiratory exchange ratio; HR: heart rate.
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Affiliation(s)
- M T Pace
- Department of Kinesiology, University of North Alabama, Florence, AL, USA
| | - J M Green
- Department of Kinesiology, University of North Alabama, Florence, AL, USA
| | - L G Killen
- Department of Kinesiology, University of North Alabama, Florence, AL, USA
| | - J C Swain
- Department of Kinesiology, University of North Alabama, Florence, AL, USA
| | - H Chander
- Department of Kinesiology, Mississippi State University, MS, USA
| | - J D Simpson
- Department of Movement Sciences and Health, University of West Florida, Pensacola, FL, USA
| | - E K O'Neal
- Department of Kinesiology, University of North Alabama, Florence, AL, USA
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14
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Fernández Menéndez A, Uva B, Favre L, Hans D, Borrani F, Malatesta D. Mass-normalized internal mechanical work in walking is not impaired in adults with class III obesity. J Appl Physiol (1985) 2020; 129:194-203. [PMID: 32584667 DOI: 10.1152/japplphysiol.00837.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been suggested that internal mechanical work (i.e., the work required to move the limbs with respect to the center of mass, Wint) may be responsible for the higher net cost of walking in obese adults, but this variable has not yet been studied in individuals with obesity. The main finding of the present study is that individuals with class III obesity exhibit a similar amount of mass-normalized Wint to that of adults with a normal body weight, suggesting that body mass-relative Wint is not affected by obesity and is not responsible for the higher energy cost and the lower efficiency of walking in this population.
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Affiliation(s)
- Aitor Fernández Menéndez
- Institute of Sport Sciences of the University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Barbara Uva
- Institute of Sport Sciences of the University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Lucie Favre
- Lausanne University Hospital (CHUV), Consultation de prévention et traitement de l’obésité, Lausanne, Switzerland
| | - Didier Hans
- Center for Bone Diseases, Lausanne University Hospital, Lausanne, Switzerland
| | - Fabio Borrani
- Institute of Sport Sciences of the University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Davide Malatesta
- Institute of Sport Sciences of the University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
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15
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Hedrick EA, Malcolm P, Wilken JM, Takahashi KZ. The effects of ankle stiffness on mechanics and energetics of walking with added loads: a prosthetic emulator study. J Neuroeng Rehabil 2019; 16:148. [PMID: 31752942 PMCID: PMC6873504 DOI: 10.1186/s12984-019-0621-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 11/07/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND The human ankle joint has an influential role in the regulation of the mechanics and energetics of gait. The human ankle can modulate its joint 'quasi-stiffness' (ratio of plantarflexion moment to dorsiflexion displacement) in response to various locomotor tasks (e.g., load carriage). However, the direct effect of ankle stiffness on metabolic energy cost during various tasks is not fully understood. The purpose of this study was to determine how net metabolic energy cost was affected by ankle stiffness while walking under different force demands (i.e., with and without additional load). METHODS Individuals simulated an amputation by using an immobilizer boot with a robotic ankle-foot prosthesis emulator. The prosthetic emulator was controlled to follow five ankle stiffness conditions, based on literature values of human ankle quasi-stiffness. Individuals walked with these five ankle stiffness settings, with and without carrying additional load of approximately 30% of body mass (i.e., ten total trials). RESULTS Within the range of stiffness we tested, the highest stiffness minimized metabolic cost for both load conditions, including a ~ 3% decrease in metabolic cost for an increase in stiffness of about 0.0480 Nm/deg/kg during normal (no load) walking. Furthermore, the highest stiffness produced the least amount of prosthetic ankle-foot positive work, with a difference of ~ 0.04 J/kg from the highest to lowest stiffness condition. Ipsilateral hip positive work did not significantly change across the no load condition but was minimized at the highest stiffness for the additional load conditions. For the additional load conditions, the hip work followed a similar trend as the metabolic cost, suggesting that reducing positive hip work can lower metabolic cost. CONCLUSION While ankle stiffness affected the metabolic cost for both load conditions, we found no significant interaction effect between stiffness and load. This may suggest that the importance of the human ankle's ability to change stiffness during different load carrying tasks may not be driven to minimize metabolic cost. A prosthetic design that can modulate ankle stiffness when transitioning from one locomotor task to another could be valuable, but its importance likely involves factors beyond optimizing metabolic cost.
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Affiliation(s)
- Erica A Hedrick
- Department of Biomechanics, University of Nebraska at Omaha, Omaha, NE, USA
| | - Philippe Malcolm
- Department of Biomechanics, University of Nebraska at Omaha, Omaha, NE, USA
| | - Jason M Wilken
- Department of Physical Therapy & Rehabilitation Science, University of Iowa, Iowa City, Iowa, USA
| | - Kota Z Takahashi
- Department of Biomechanics, University of Nebraska at Omaha, Omaha, NE, USA.
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16
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Denize KM, Akbari P, da Silva DF, Haman F, Adamo KB. Greater energy demand of exercise during pregnancy does not impact mechanical efficiency. Appl Physiol Nutr Metab 2019; 45:493-499. [PMID: 31614094 DOI: 10.1139/apnm-2019-0450] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pregnant women are recommended to engage in 150 min of moderate-intensity physical activity per week to reduce pregnancy complications. Many women struggle to remain physically active throughout pregnancy, and there is no consensus about whether women adopt a less efficient movement pattern as they progress through pregnancy and experience gestational weight gain. This study assessed the change in energy expenditure and mechanical efficiency in pregnant women (PREG; n = 10) when performing a walking treadmill task in early, mid, and late pregnancy and also compared with an age- and body mass index-matched, nonpregnant (CON; n = 10) group. On average, the PREG group gained within the Institute of Medicine's gestational weight gain guidelines (11.6 ± 3.6 kg) and were all inactive (measured using accelerometry), except for 1 participant, by the third trimester, as per the 2019 Canadian physical activity guidelines for pregnant women. Energy expended to complete the walking task increased throughout pregnancy and was higher than the controls (111.5 ± 24.6 kcal) in mid and late pregnancy (139.0 ± 22.2 kcal, p = 0.02, and 147.3 ± 24.6 kcal, p = 0.005, respectively), but not early pregnancy (129.9 ± 18.9 kcal, p = 0.08). Walking mechanical efficiency was similar within pregnant women at each time point and compared to nonpregnant controls. Our findings add to the growing body of evidence demonstrating that pregnant women can safely perform physical activity by showing that walking mechanical efficiency is unchanged at low to moderate intensities. Novelty Energy demand during exercise increases proportionally to weight gain across pregnancy trimesters. However, mechanical efficiency remains unchanged during low- to moderate-intensity walking.
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Affiliation(s)
- Kathryn M Denize
- Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Pegah Akbari
- Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Danilo Fernandes da Silva
- Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Francois Haman
- Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Kristi B Adamo
- Department of Human Kinetics, Faculty of Health Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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17
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Bode VG, Croce RV, Quinn TJ, Laroche DP. Influence of excess weight on lower-extremity vertical stiffness and metabolic cost of walking. Eur J Sport Sci 2019; 20:477-485. [PMID: 31405356 DOI: 10.1080/17461391.2019.1652350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The purpose was to test whether lower-extremity vertical stiffness and gait mechanics explain differences in energy cost of walking (Cw) between individuals with normal weight (NW) and obesity (OB). Ten OB (33.1 ± 2.0 kg m-2) and 10 NW (24.2 ± 1.3 kg m-2) walked for six minutes on an instrumented treadmill at 1.25 m s-1 while Cw, lower-extremity kinematics, and vertical stiffness (K vert) were measured. NW completed another trial with a loaded vest (NWL) to simulate the BMI of the obese group. Cw was 24% greater in OB (277.5 ± 45.3 J m-1) and 23% greater in NWL (272.7 ± 35.7 J m-1) than NW (211.0 ± 27.0 J m-1, P < 0.005). Mass-specific Cw (Cwkg) wasn't different between conditions (P = 0.085). Lower-extremity K vert was 40% higher in OB (32.7 ± 5.2 kN m-1) than NW (23.3 ± 4.7 kN m-1, P < 0.001), but neither was different from NWL (27.5 ± 3.4 kN m-1, P > 0.05). Mass-specific K vert (P = 0.081) was similar across conditions. K vert was related to Cw (r = 0.55, P = 0.001). Cwkg wasn't different between NW or OB, but there was a negative correlation between BMI and Cwkg driven by lower Cwkg in NWL. Cw and K vert covaried in proportion to body mass, but mass-specific K vert was unrelated to Cwkg. Mass-specific K vert was lower in NWL than OB due to NWL's greater angle of attack, center of mass displacement, and joint range of motion.
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Affiliation(s)
- Victoria G Bode
- Department of Kinesiology, University of New Hampshire, Durham, NH, USA
| | - Ronald V Croce
- Department of Kinesiology, University of New Hampshire, Durham, NH, USA
| | - Timothy J Quinn
- Department of Kinesiology, University of New Hampshire, Durham, NH, USA
| | - Dain P Laroche
- Department of Kinesiology, University of New Hampshire, Durham, NH, USA
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18
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Lenton GK, Doyle TLA, Lloyd DG, Higgs J, Billing D, Saxby DJ. Lower-limb joint work and power are modulated during load carriage based on load configuration and walking speed. J Biomech 2018; 83:174-180. [PMID: 30527387 DOI: 10.1016/j.jbiomech.2018.11.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 09/26/2018] [Accepted: 11/23/2018] [Indexed: 11/30/2022]
Abstract
Soldiers regularly transport loads weighing >20 kg at slow speeds for long durations. These tasks elicit high energetic costs through increased positive work generated by knee and ankle muscles, which may increase risk of muscular fatigue and decrease combat readiness. This study aimed to determine how modifying where load is borne changes lower-limb joint mechanical work production, and if load magnitude and/or walking speed also affect work production. Twenty Australian soldiers participated, donning a total of 12 body armor variations: six different body armor systems (one standard-issue, two commercially available [cARM1-2], and three prototypes [pARM1-3]), each worn with two different load magnitudes (15 and 30 kg). For each armor variation, participants completed treadmill walking at two speeds (1.51 and 1.83 m/s). Three-dimensional motion capture and force plate data were acquired and used to estimate joint angles and moments from inverse kinematics and dynamics, respectively. Subsequently, hip, knee, and ankle joint work and power were computed and compared between armor types and walking speeds. Positive joint work over the stance phase significantly increased with walking speed and carried load, accompanied by 2.3-2.6% shifts in total positive work production from the ankle to the hip (p < 0.05). Compared to using cARM1 with 15 kg carried load, carrying 30 kg resulted in significantly greater hip contribution to total lower-limb positive work, while knee and ankle work decreased. Substantial increases in hip joint contributions to total lower-limb positive work that occur with increases in walking speed and load magnitude highlight the importance of hip musculature to load carriage walking.
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Affiliation(s)
- Gavin K Lenton
- Gold Coast Orthopaedics Research, Engineering and Education Alliance, Menzies Health Institute Queensland, School of Allied Health Sciences, Griffith University, 58 Parklands Drive, Southport, Queensland 4215, Australia.
| | - Tim L A Doyle
- Department of Health Professions, Faculty of Medicine and Health Sciences, Macquarie University, Balaclava Road, North Ryde, New South Wales 2109, Australia.
| | - David G Lloyd
- Gold Coast Orthopaedics Research, Engineering and Education Alliance, Menzies Health Institute Queensland, School of Allied Health Sciences, Griffith University, 58 Parklands Drive, Southport, Queensland 4215, Australia.
| | - Jeremy Higgs
- Gold Coast Orthopaedics Research, Engineering and Education Alliance, Menzies Health Institute Queensland, School of Allied Health Sciences, Griffith University, 58 Parklands Drive, Southport, Queensland 4215, Australia.
| | - Daniel Billing
- Land Division, Defence Science and Technology Group, 506 Lorimer Street, Fishermans Bend, VIC 3207, Australia.
| | - David J Saxby
- Gold Coast Orthopaedics Research, Engineering and Education Alliance, Menzies Health Institute Queensland, School of Allied Health Sciences, Griffith University, 58 Parklands Drive, Southport, Queensland 4215, Australia.
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19
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Comparing the Effects of Different Body Armor Systems on the Occupational Performance of Police Officers. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15050893. [PMID: 29723995 PMCID: PMC5981932 DOI: 10.3390/ijerph15050893] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 04/27/2018] [Accepted: 04/28/2018] [Indexed: 11/16/2022]
Abstract
Policing duties may inherently be dangerous due to stab, blunt trauma and ballistic threats. The addition of individual light armor vests (ILAVs) has been suggested as a means to protect officers. However, the addition of the extra load of the ILAV may affect officer ability to conduct occupational tasks. The purpose of this study was to determine if wearing any of three different ILAVs made by different companies with their preferred materials and designs (ILAV A, 4.68 percent body weight, ILAV B, 4.05 percent body weight, & ILAV C, 3.71 percent body weight) affected occupational task performance when compared to that in normal station wear. A prospective, within-subjects repeated measures design was employed, using a counterbalanced randomization in which each ILAV was worn for an entire day while officers completed a variety of occupationally relevant tasks. These tasks included a victim drag, car exit and 5-meter sprint, step down and marksmanship task. To compare the effects of the ILAVs on these tasks, a multivariate repeated measures analysis of variance (ANOVA) was conducted, with post hoc pairwise comparisons using a Bonferroni adjustment. Results showed that performance in each task did not vary between any of the ILAV or normal station wear conditions. There was less variability in the marksmanship task with ILAV B, however. The results suggest that none of the ILAVs used in this study were heavy enough to significantly affect task performance in the assessed tasks when compared to wearing normal station wear.
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20
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The role of military footwear and workload on ground reaction forces during a simulated lateral ankle sprain mechanism. Foot (Edinb) 2018; 34:53-57. [PMID: 29288908 DOI: 10.1016/j.foot.2017.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/10/2017] [Accepted: 11/19/2017] [Indexed: 02/04/2023]
Abstract
BACKGROUND Ankle sprains are a common orthopedic injury in military populations, which may be attributed to occupational demands and footwear. Minimalist military boots have become popular, but their influence on ground reaction force (GRF) attenuation capabilities during an ankle inversion perturbation are unknown. Therefore, the purpose of this study was to examine potential differences in GRFs during an ankle inversion perturbation in a standard issue (STN) and minimalist military boot (MIN) before and after a simulated military workload. METHODS Twenty-one healthy adult males completed an ankle inversion perturbation protocol in each footwear condition before and after an incremental treadmill exercise protocol to volitional exhaustion while wearing a 16kg rucksack. The ankle inversion perturbation protocol consisted of stepping down from a 27cm box onto a force platform with a fulcrum (FUL), which created 25° of inversion upon landing, or flat (FLT) outer sole attached to the plantar aspect of the participants' footwear in random order. Peak vertical, anterior/posterior, and medial/lateral components of the GRF during FUL and FLT conditions were assessed, normalized to multiples of body weight in each footwear. Dependent variables were then analyzed using separate 2 (footwear)×2 (time) repeated measures ANOVA (p<0.05). RESULTS The MIN footwear demonstrated significantly greater vertical GRF and significantly less medial GRF during the FUL condition. CONCLUSIONS These results indicate that various mechanical and design characteristics of military footwear may influence GRF attenuation capabilities and ankle joint loading when the foot/ankle complex is forced into inversion.
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21
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Respiratory Effects of Thoracic Load Carriage Exercise and Inspiratory Muscle Training as a Strategy to Optimize Respiratory Muscle Performance with Load Carriage. ACTA ACUST UNITED AC 2017; 5:49-64. [PMID: 29630067 DOI: 10.1007/s40362-017-0046-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Many occupational and recreational settings require the use of protective and/or load-bearing apparatuses worn over the thoracic cavity, known as thoracic load carriage (LC). Compared to normal, unloaded exercise, thoracic LC exercise places an additional demand on the respiratory and limb locomotor systems by altering ventilatory mechanics as well as circulatory responses to exercise, thus accelerating the development of fatigue in the diaphragm and accessory respiratory muscles compared to unloaded exercise. This may be a consequence of the unique demands of thoracic LC, which places an additional mass load on the thoracic cavity and can restrict chest wall expansion. Therefore it is important to find effective strategies to ameliorate the detrimental effects of thoracic LC. Inspiratory muscle training is an intervention that aims to increase the strength and endurance of the diaphragm and accessory inspiratory muscle and may therefore be a useful strategy to optimize performance with thoracic LC.
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22
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Ludlow LW, Weyand PG. Walking economy is predictably determined by speed, grade, and gravitational load. J Appl Physiol (1985) 2017; 123:1288-1302. [DOI: 10.1152/japplphysiol.00504.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 11/22/2022] Open
Abstract
The metabolic energy that human walking requires can vary by more than 10-fold, depending on the speed, surface gradient, and load carried. Although the mechanical factors determining economy are generally considered to be numerous and complex, we tested a minimum mechanics hypothesis that only three variables are needed for broad, accurate prediction: speed, surface grade, and total gravitational load. We first measured steady-state rates of oxygen uptake in 20 healthy adult subjects during unloaded treadmill trials from 0.4 to 1.6 m/s on six gradients: −6, −3, 0, 3, 6, and 9°. Next, we tested a second set of 20 subjects under three torso-loading conditions (no-load, +18, and +31% body weight) at speeds from 0.6 to 1.4 m/s on the same six gradients. Metabolic rates spanned a 14-fold range from supine rest to the greatest single-trial walking mean (3.1 ± 0.1 to 43.3 ± 0.5 ml O2·kg-body−1·min−1, respectively). As theorized, the walking portion (V̇o2-walk = V̇o2-gross – V̇o2-supine-rest) of the body’s gross metabolic rate increased in direct proportion to load and largely in accordance with support force requirements across both speed and grade. Consequently, a single minimum-mechanics equation was derived from the data of 10 unloaded-condition subjects to predict the pooled mass-specific economy (V̇o2-gross, ml O2·kg-body + load−1·min−1) of all the remaining loaded and unloaded trials combined ( n = 1,412 trials from 90 speed/grade/load conditions). The accuracy of prediction achieved ( r2 = 0.99, SEE = 1.06 ml O2·kg−1·min−1) leads us to conclude that human walking economy is predictably determined by the minimum mechanical requirements present across a broad range of conditions. NEW & NOTEWORTHY Introduced is a “minimum mechanics” model that predicts human walking economy across a broad range of conditions from only three variables: speed, surface grade, and body-plus-load mass. The derivation/validation data set includes steady-state loaded and unloaded walking trials ( n = 3,414) that span a fourfold range of walking speeds on each of six different surface gradients (−6 to +9°). The accuracy of our minimum mechanics model ( r2 = 0.99; SEE = 1.06 ml O2·kg−1·min−1) appreciably exceeds that of currently used standards.
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Affiliation(s)
- Lindsay W. Ludlow
- Locomotor Performance Laboratory, Department of Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas
| | - Peter G. Weyand
- Locomotor Performance Laboratory, Department of Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas
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23
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Ketko I, Plotnik M, Yanovich R, Gefen A, Heled Y. Wheeled assistive device for load carriage - the effects on human gait and biomechanics. ERGONOMICS 2017; 60:1415-1424. [PMID: 28393680 DOI: 10.1080/00140139.2017.1308561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Soldiers are often required to carry loads which impose biomechanical strain on the human body. This can adversely affect physical performances. Recently, wheel-based devices (WBD) were designed to reduce the load on the soldier. In the present study, a prototype of this newly developed WBD was evaluated. Thirteen volunteers performed three exercise protocols on a treadmill as follows: (1) no load; (2) carrying 40% of their bodyweight with a backpack or; (3) with the WBD. Data acquisition included: gait parameters, vertical ground reaction forces (VGRF) and contact pressure acting on the shoulder. Biomechanical analysis showed that the WBD decreased the contact pressure on the shoulder and the VGRF. However, greater gait variability, in terms of cycle-to-cycle gait line generation, was observed, which might point to a difficulty in maintaining stability while walking. The study suggests that WBD has a potential to reduce the biomechanical strain on the soldier while carrying heavy loads. Future potential adjustments for the development of a better WBD-based solution are suggested. Practitioner Summary: The present research observed the potential biomechanical advantages of using a wheel-based device designed to reduce the load on the soldier. It contributed to a lower mechanical force on the soldier's body, yet causing modulations in gait control. Future design adjustments should be made to optimise the platform.
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Affiliation(s)
- Itay Ketko
- a The Warrior Health Research Institute, Israel Defense Forces, Medical Corps , Ramat Gan , Israel
- b Heller Institute of Medical Research, Sheba Medical Center , Tel Hashomer , Israel
- c Faculty of Engineering, Department of Biomedical Engineering , Tel Aviv University , Israel
| | - Meir Plotnik
- d The Center of Advanced Technologies in Rehabilitation, Sheba Medical Center , Tel Hashomer , Israel
- e Sackler Faculty of Medicine, Department of Physiology and Pharmacology , Tel Aviv University , Tel Aviv , Israel
- f Gonda Brain Research Center, Bar Ilan University , Ramat Gan , Israel
- g Sagol School of Neuroscience, Tel Aviv University , Tel Aviv , Israel
| | - Ran Yanovich
- a The Warrior Health Research Institute, Israel Defense Forces, Medical Corps , Ramat Gan , Israel
- b Heller Institute of Medical Research, Sheba Medical Center , Tel Hashomer , Israel
| | - Amit Gefen
- c Faculty of Engineering, Department of Biomedical Engineering , Tel Aviv University , Israel
| | - Yuval Heled
- b Heller Institute of Medical Research, Sheba Medical Center , Tel Hashomer , Israel
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24
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Physiological and Biomechanical Responses to Prolonged Heavy Load Carriage During Level Treadmill Walking in Females. J Appl Biomech 2017; 33:248-255. [DOI: 10.1123/jab.2016-0185] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Heavy load carriage has been identified as a main contributing factor to the high incidence of overuse injuries in soldiers. Peak vertical ground reaction force (VGRFMAX) and maximal vertical loading rates (VLRMAX) may increase during heavy prolonged load carriage with the development of muscular fatigue and reduced shock attenuation capabilities. The objectives of the current study were (1) to examine physiological and biomechanical changes that occur during a prolonged heavy load carriage task, and (2) to examine if this task induces neuromuscular fatigue and changes in muscle architecture. Eight inexperienced female participants walked on an instrumented treadmill carrying operational loads for 60 minutes at 5.4 km·h–1. Oxygen consumption (), heart rate, rating of perceived exertion (RPE), trunk lean angle, and ground reaction forces were recorded continuously during task. Maximal force and in-vivo muscle architecture were assessed pre- and posttask. Significant increases were observed for VGRFMAX, VLRMAX, trunk lean angle,, heart rate, and RPE during the task. Increased vastus lateralis fascicle length and decreased maximal force production were also observed posttask. Prolonged heavy load carriage, in an inexperienced population carrying operational loads, results in progressive increases in ground reaction force parameters that have been associated with overuse injury.
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Hinde K, Lloyd R, Low C, Cooke C. The effect of temperature, gradient, and load carriage on oxygen consumption, posture, and gait characteristics. Eur J Appl Physiol 2017; 117:417-430. [PMID: 28154976 PMCID: PMC5346415 DOI: 10.1007/s00421-016-3531-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 12/29/2016] [Indexed: 11/03/2022]
Abstract
PURPOSE The purpose of this experiment was to evaluate the effect of load carriage in a range of temperatures to establish the interaction between cold exposure, the magnitude of change from unloaded to loaded walking and gradient. METHODS Eleven participants (19-27 years) provided written informed consent before performing six randomly ordered walking trials in six temperatures (20, 10, 5, 0, -5, and -10 °C). Trials involved two unloaded walking bouts before and after loaded walking (18.2 kg) at 4 km · h-1, on 0 and 10% gradients in 4 min bouts. RESULTS The change in absolute oxygen consumption (V̇O2) from the first unloaded bout to loaded walking was similar across all six temperatures. When repeating the second unloaded bout, V̇O2 at both -5 and -10 °C was greater compared to the first. At -10 °C, V̇O2 was increased from 1.60 ± 0.30 to 1.89 ± 0.51 L · min-1. Regardless of temperature, gradient had a greater effect on V̇O2 and heart rate (HR) than backpack load. HR was unaffected by temperature. Stride length (SL) decreased with decreasing temperature, but trunk forward lean was greater during cold exposure. CONCLUSION Decreased ambient temperature did not influence the magnitude of change in V̇O2 from unloaded to loaded walking. However, in cold temperatures, V̇O2 was significantly higher than in warm conditions. The increased V̇O2 in colder temperatures at the same exercise intensity is predicted to ultimately lead to earlier onset of fatigue and cessation of exercise. These results highlight the need to consider both appropriate clothing and fitness during cold exposure.
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Affiliation(s)
- Katrina Hinde
- Leeds Beckett University, Headingley Campus, Leeds, West Yorkshire, LS6 3QS, UK.
| | - Ray Lloyd
- Leeds Trinity University, Brownberrie Lane, Horsforth, Leeds, LS18 5HD, UK
| | - Chris Low
- Leeds Beckett University, Headingley Campus, Leeds, West Yorkshire, LS6 3QS, UK
| | - Carlton Cooke
- Leeds Trinity University, Brownberrie Lane, Horsforth, Leeds, LS18 5HD, UK
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26
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Pasiakos SM, McClung HL, Margolis LM, Murphy NE, Lin GG, Hydren JR, Young AJ. Human Muscle Protein Synthetic Responses during Weight-Bearing and Non-Weight-Bearing Exercise: A Comparative Study of Exercise Modes and Recovery Nutrition. PLoS One 2015; 10:e0140863. [PMID: 26474292 PMCID: PMC4608805 DOI: 10.1371/journal.pone.0140863] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 10/01/2015] [Indexed: 12/05/2022] Open
Abstract
Effects of conventional endurance (CE) exercise and essential amino acid (EAA) supplementation on protein turnover are well described. Protein turnover responses to weighted endurance exercise (i.e., load carriage, LC) and EAA may differ from CE, because the mechanical forces and contractile properties of LC and CE likely differ. This study examined muscle protein synthesis (MPS) and whole-body protein turnover in response to LC and CE, with and without EAA supplementation, using stable isotope amino acid tracer infusions. Forty adults (mean ± SD, 22 ± 4 y, 80 ± 10 kg, VO2peak 4.0 ± 0.5 L∙min-1) were randomly assigned to perform 90 min, absolute intensity-matched (2.2 ± 0.1 VO2 L∙m-1) LC (performed on a treadmill wearing a vest equal to 30% of individual body mass, mean ± SD load carried 24 ± 3 kg) or CE (cycle ergometry performed at the same absolute VO2 as LC) exercise, during which EAA (10 g EAA, 3.6 g leucine) or control (CON, non-nutritive) drinks were consumed. Mixed-muscle and myofibrillar MPS were higher during exercise for LC than CE (mode main effect, P < 0.05), independent of dietary treatment. EAA enhanced mixed-muscle and sarcoplasmic MPS during exercise, regardless of mode (drink main effect, P < 0.05). Mixed-muscle and sarcoplasmic MPS were higher in recovery for LC than CE (mode main effect, P < 0.05). No other differences or interactions (mode x drink) were observed. However, EAA attenuated whole-body protein breakdown, increased amino acid oxidation, and enhanced net protein balance in recovery compared to CON, regardless of exercise mode (P < 0.05). These data show that, although whole-body protein turnover responses to absolute VO2-matched LC and CE are the same, LC elicited a greater muscle protein synthetic response than CE.
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Affiliation(s)
- Stefan M. Pasiakos
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
- * E-mail:
| | - Holly L. McClung
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Lee M. Margolis
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Nancy E. Murphy
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Gregory G. Lin
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Jay R. Hydren
- Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Andrew J. Young
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
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27
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Walker RE, Swain DP, Ringleb SI, Colberg SR. Effect of Added Mass on Treadmill Performance and Pulmonary Function. J Strength Cond Res 2015; 29:882-8. [DOI: 10.1519/jsc.0000000000000408] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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28
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Seay JF. Biomechanics of Load Carriage. STUDIES IN MECHANOBIOLOGY, TISSUE ENGINEERING AND BIOMATERIALS 2015. [DOI: 10.1007/8415_2015_185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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29
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Ward J, Coats J, Pourmoghaddam A. Spine buddy® supportive pad impact on single-leg static balance and a jogging gait of individuals wearing a military backpack. J Hum Kinet 2014; 44:53-66. [PMID: 25713665 PMCID: PMC4327380 DOI: 10.2478/hukin-2014-0110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The Spine Buddy® supportive pad was developed to be inserted underneath military backpacks to help disperse the heavy load of the backpack. The purpose of this study was to determine the impact the additional supportive pad had on static balance and a running gait while wearing a military backpack. Forty healthy subjects (age= 27.5 + 5.6 yrs, body height= 1.78 + 0.06 m, body mass= 86.5 + 14.0 kg: mean + SD) participated in a static single-leg balance test on a force plate with each lower limb while wearing a 15.9 kg military backpack for 30 s. Following this, participants were randomized to one of two interventions: 1) Intervention, which wore the Spine Buddy® supportive pad underneath their backpack or 2) Control, with no additional supportive pad. Post-intervention measurements of static single-leg balance were then recorded. Afterwards, a similar pre vs post testing schedule and randomization scheme was used to test the impact of the supportive pad on a 5 mph jogging gait using Vicon® cameras. Within-group data were analyzed with a 2-way repeated measures ANOVA. Statistically significant differences were not seen between the control and experimental group for balance and gait variables. Preliminarily, this suggests that the Spine Buddy® supportive pad causes no deleterious effect on static balance and a jogging gait in 18-45 year-old asymptomatic individuals.
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Affiliation(s)
- John Ward
- Department of Physiology and Chemistry, Texas Chiropractic College
| | - Jesse Coats
- Department of Clinical Specialties, Texas Chiropractic College
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30
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Huang TWP, Kuo AD. Mechanics and energetics of load carriage during human walking. J Exp Biol 2014; 217:605-13. [PMID: 24198268 PMCID: PMC3922835 DOI: 10.1242/jeb.091587] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 10/16/2013] [Indexed: 11/20/2022]
Abstract
Although humans clearly expend more energy to walk with an extra load, it is unclear what biomechanical mechanisms contribute to that increase. One possible contribution is the mechanical work performed on the body center of mass (COM), which simple models predict should increase linearly with added mass. The work should be performed primarily by the lower extremity joints, although in unknown distribution, and cost a proportionate amount of metabolic energy. We therefore tested normal adults (N=8) walking at constant speed (1.25 m s(-1)) with varying backpack loads up to 40% of body weight. We measured mechanical work (both performed on the COM and joint work from inverse dynamics), as well as metabolic energy expenditure through respirometry. Both measures of work were found to increase approximately linearly with carried load, with COM work rate increasing by approximately 1.40 W for each 1 kg of additional load. The joints all contributed work, but the greatest increase in positive work was attributable to the ankle during push-off (45-60% of stride time) and the knee in the rebound after collision (12-30% stride). The hip performed increasing amounts of negative work, near the end of stance. Rate of metabolic energy expenditure also increased approximately linearly with load, by approximately 7.6 W for each 1 kg of additional load. The ratio of the increases in work and metabolic cost yielded a relatively constant efficiency of approximately 16%. The metabolic cost not explained by work appeared to be relatively constant with load and did not exhibit a particular trend. Most of the increasing cost for carrying a load appears to be explained by positive mechanical work, especially about the ankle and knee, with both work and metabolic cost increasing nearly linearly with added mass.
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Affiliation(s)
- Tzu-wei P. Huang
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Arthur D. Kuo
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
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31
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Pasiakos SM, Montain SJ, Young AJ. Protein supplementation in U.S. military personnel. J Nutr 2013; 143:1815S-1819S. [PMID: 24027181 DOI: 10.3945/jn.113.175968] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Protein supplements (PSs) are, after multivitamins, the most frequently consumed dietary supplement by U.S. military personnel. Warfighters believe that PSs will improve health, promote muscle strength, and enhance physical performance. The estimated prevalence of regular PS use by military personnel is nearly 20% or more in active-duty personnel, which is comparable to collegiate athletes and recreationally active adults, but higher than that for average U.S. civilians. Although the acute metabolic effects of PS ingestion are well described, little is known regarding the benefits of PS use by warfighters in response to the metabolic demands of military operations. When dietary protein intake approaches 1.5 g · kg(-1) · d(-1), and energy intake matches energy expenditure, the use of PSs by most physically active military personnel may not be necessary. However, dismounted infantry often perform operations consisting of long periods of strenuous physical activity coupled with inadequate dietary energy and protein intake. In these situations, the use of PSs may have efficacy for preserving fat-free mass. This article reviews the available literature regarding the prevalence of PS use among military personnel. Furthermore, it highlights the unique metabolic stressors affecting U.S. military personnel and discusses potential conditions during which protein supplementation might be beneficial.
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Affiliation(s)
- Stefan M Pasiakos
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA
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32
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Browning RC, Reynolds MM, Board WJ, Walters KA, Reiser RF. Obesity does not impair walking economy across a range of speeds and grades. J Appl Physiol (1985) 2013; 114:1125-31. [PMID: 23412900 DOI: 10.1152/japplphysiol.00765.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Despite the popularity of walking as a form of physical activity for obese individuals, relatively little is known about how obesity affects the metabolic rate, economy, and underlying mechanical energetics of walking across a range of speeds and grades. The purpose of this study was to quantify metabolic rate, stride kinematics, and external mechanical work during level and gradient walking in obese and nonobese adults. Thirty-two obese [18 women, mass = 102.1 (15.6) kg, BMI = 33.9 (3.6) kg/m(2); mean (SD)] and 19 nonobese [10 women, mass = 64.4 (10.6) kg, BMI = 21.6 (2.0) kg/m(2)] volunteers participated in this study. We measured oxygen consumption, ground reaction forces, and lower extremity kinematics while subjects walked on a dual-belt force-measuring treadmill at 11 speeds/grades (0.50-1.75 m/s, -3° to +9°). We calculated metabolic rate, stride kinematics, and external work. Net metabolic rate (Ė net/kg, W/kg) increased with speed or grade across all individuals. Surprisingly and in contrast with previous studies, Ė net/kg was 0-6% less in obese compared with nonobese adults (P = 0.013). External work, although a primary determinant of Ė net/kg, was not affected by obesity across the range of speeds/grades used in this study. We also developed new prediction equations to estimate oxygen consumption and Ė net/kg and found that Ė net/kg was positively related to relative leg mass and step width and negatively related to double support duration. These results suggest that obesity does not impair walking economy across a range of walking speeds and grades.
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Affiliation(s)
- Raymond C Browning
- Department of Health and Exercise Science, Colorado State University, Ft. Collins, Colorado 80523-1582, USA.
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Effects of extreme-duration heavy load carriage on neuromuscular function and locomotion: a military-based study. PLoS One 2012; 7:e43586. [PMID: 22927995 PMCID: PMC3425486 DOI: 10.1371/journal.pone.0043586] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 07/23/2012] [Indexed: 11/29/2022] Open
Abstract
Trekking and military missions generally consist of carrying heavy loads for extreme durations. These factors have been separately shown to be sources of neuromuscular (NM) fatigue and locomotor alterations. However, the question of their combined effects remains unresolved, and addressing this issue required a representative context.
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