Added mass provided irregular interference towards human movement and shifted the force generated by lower limb muscles.However,the association between mass and muscle activities is not well recognized.Our study aims ...Added mass provided irregular interference towards human movement and shifted the force generated by lower limb muscles.However,the association between mass and muscle activities is not well recognized.Our study aims at investigating the influence of added mass on lower limbs.In our study,five young,healthy walkers performed walking trials under three load conditions(unload;C1:0.25 pounds on feet,1 pound on calves,and 2 pounds on thighs;C2:1 pound on feet,2 pounds on calves,and 4 pounds on thighs).During walking,three-dimensional kinematics,sEMG signals,and oxygen consumption were collected which allowed us to understand the effects of added mass on muscles.We also generated OpenSim simulation,designed to comprehend the relationship between added mass and muscles.With the increase of added mass,maximum sEMG signal and peak joint torque increased;whereas,the horizontal stride time reduced(unload:1.697±0.02 s,C1:1.651±0.02 s,C2:1.622±0.02 s).Energy expenditure raised correspondingly(C1:6.53%,C2:24.85%).Moreover,joint moment increased,while same change occurred in muscle force.Overall,our results show that participants responded positively to additional mass by adjusting muscle activities,joint movement,and stride frequency,which demonstrates the relationship between energy consumption and added mass.展开更多
Background: The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. The degree of maximum oxygen c...Background: The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. The degree of maximum oxygen consumption changes at high altitudes was also examined.Methods: Twelve Indian Army soldiers were acclimatized at altitudes of 3,505 m and 4,300 m. They walked for 10 minutes on a motorized treadmill at 2.5km/h and 3.5km/h speeds during carrying no loads and three magnitudes of load(10.7kg, 21.4kg, 30kg) at both altitudes. Physiological parameters such as oxygen consumption, energy expenditure, heart rate, and ventilation were recorded for each breath using a gas analyzer. The rating of perceived exertion was also noted after each load carriage session. Maximal oxygen consumption(VO2max) was measured at sea level and the two high altitudes, and respective relative workloads(% of VO2max) were calculated from oxygen consumption. Repeated measure ANOVA was applied to reveal the significant effects of the independent variables.Results: The participants had significant reductions in VO2 max with rising altitude. Marked increases in almost all physiological parameters were observed with increasing load, altitude, and speed. The soldiers expressed heavy perceived exertion levels with higher loads at 3.5km/h at the two high altitudes.Conclusions: Considering the physiological responses, expressions of perceived exertion and changes in relative work load at both of the high altitudes. Indian soldiers are advised to walk slowly with adequate rest in between their schedules and to carry not more than 32% of their body weight.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.51205182)Key research&Development plan of Jiangsu Province(Grant No.BE2019724).
文摘Added mass provided irregular interference towards human movement and shifted the force generated by lower limb muscles.However,the association between mass and muscle activities is not well recognized.Our study aims at investigating the influence of added mass on lower limbs.In our study,five young,healthy walkers performed walking trials under three load conditions(unload;C1:0.25 pounds on feet,1 pound on calves,and 2 pounds on thighs;C2:1 pound on feet,2 pounds on calves,and 4 pounds on thighs).During walking,three-dimensional kinematics,sEMG signals,and oxygen consumption were collected which allowed us to understand the effects of added mass on muscles.We also generated OpenSim simulation,designed to comprehend the relationship between added mass and muscles.With the increase of added mass,maximum sEMG signal and peak joint torque increased;whereas,the horizontal stride time reduced(unload:1.697±0.02 s,C1:1.651±0.02 s,C2:1.622±0.02 s).Energy expenditure raised correspondingly(C1:6.53%,C2:24.85%).Moreover,joint moment increased,while same change occurred in muscle force.Overall,our results show that participants responded positively to additional mass by adjusting muscle activities,joint movement,and stride frequency,which demonstrates the relationship between energy consumption and added mass.
基金funded through Project No.S&T-09/DIP-251,C3.0 from the Defence Research and Development Organization(DRDO),Ministry of Defence,Government of India
文摘Background: The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. The degree of maximum oxygen consumption changes at high altitudes was also examined.Methods: Twelve Indian Army soldiers were acclimatized at altitudes of 3,505 m and 4,300 m. They walked for 10 minutes on a motorized treadmill at 2.5km/h and 3.5km/h speeds during carrying no loads and three magnitudes of load(10.7kg, 21.4kg, 30kg) at both altitudes. Physiological parameters such as oxygen consumption, energy expenditure, heart rate, and ventilation were recorded for each breath using a gas analyzer. The rating of perceived exertion was also noted after each load carriage session. Maximal oxygen consumption(VO2max) was measured at sea level and the two high altitudes, and respective relative workloads(% of VO2max) were calculated from oxygen consumption. Repeated measure ANOVA was applied to reveal the significant effects of the independent variables.Results: The participants had significant reductions in VO2 max with rising altitude. Marked increases in almost all physiological parameters were observed with increasing load, altitude, and speed. The soldiers expressed heavy perceived exertion levels with higher loads at 3.5km/h at the two high altitudes.Conclusions: Considering the physiological responses, expressions of perceived exertion and changes in relative work load at both of the high altitudes. Indian soldiers are advised to walk slowly with adequate rest in between their schedules and to carry not more than 32% of their body weight.
