An investigation of perceived exertion via whole body exertion and direct muscle force indicators during the determination of the maximum acceptable weight of lift

Ergonomics ◽  
2000 ◽  
Vol 43 (2) ◽  
pp. 143-159 ◽  
Author(s):  
Kermit G. Davis ◽  
Michael J. Jorgensen ◽  
William S. Marras
Author(s):  
Brian D. Lowe

Psychophysical approaches to quantifying perceived effort have been used to evaluate the physical demand of many industrial work activities. An experiment was conducted to examine the relationship between ratings of whole-body perceived exertion and differentiated, regional ratings of exertion. The Borg, CR-10 scale was used by 16 subjects performing a simulated repetitive lifting task. Ratings of perceived exertion were obtained for the arms, legs, torso, and central (cardiorespiratory) effort sensations as well as a rating of overall, whole-body exertion. A multiple linear regression analysis was used to predict the whole-body rating of exertion from the differentiated ratings in lifting tasks using both a squat and stoop posture. In the stoop posture condition the coefficient of determination between whole-body perceived exertion and the model including arm, torso, and central ratings was R2=0.81. In the squat posture condition, the final regression model predicting whole-body exertion contained only the rating from the legs (R2 = 0.62). Differentiated ratings explained the majority of the variance in whole-body perceived exertion for squat and stoop lifting tasks.


Author(s):  
Cécile Bétry ◽  
Aline V. Nixon ◽  
Paul L. Greenhaff ◽  
Elizabeth J. Simpson

Abstract Introduction Skeletal muscle is a major site for whole-body glucose disposal, and determination of skeletal muscle glucose uptake is an important metabolic measurement, particularly in research focussed on interventions that impact muscle insulin sensitivity. Calculating arterial-venous difference in blood glucose can be used as an indirect measure for assessing glucose uptake. However, the possibility of multiple tissues contributing to the composition of venous blood, and the differential in glucose uptake kinetics between tissue types, suggests that sampling from different vein sites could influence the estimation of glucose uptake. This study aimed to determine the impact of venous cannula position on calculated forearm glucose uptake following an oral glucose challenge in resting and post-exercise states. Materials and Methods In 9 young, lean, males, the impact of sampling blood from two antecubital vein positions; the perforating vein (‘perforating’ visit) and, at the bifurcation of superficial and perforating veins (‘bifurcation’ visit), was assessed. Brachial artery blood flow and arterialised-venous and venous blood glucose concentrations were measured in 3 physiological states; resting-fasted, resting-fed, and fed following intermittent forearm muscle contraction (fed-exercise). Results Following glucose ingestion, forearm glucose uptake area under the curve was greater for the ‘perforating’ than for the ‘bifurcation’ visit in the resting-fed (5.92±1.56 vs. 3.69±1.35 mmol/60 min, P<0.01) and fed-exercise (17.38±7.73 vs. 11.40±7.31 mmol/75 min, P<0.05) states. Discussion Antecubital vein cannula position impacts calculated postprandial forearm glucose uptake. These findings have implications for longitudinal intervention studies where serial determination of forearm glucose uptake is required.


2012 ◽  
Vol 7 (4) ◽  
pp. 332-339 ◽  
Author(s):  
Jordan P.R. McIntyre ◽  
Grant A. Mawston ◽  
Simeon P. Cairns

Purpose:To quantify how whole-body power, muscle-function, and jump-performance measures change during prolonged cycling and recovery and determine whether there are relationships between the different fatigue measures.Methods:Ten competitive or recreationally active male cyclists underwent repeated 20-min stages of prolonged cycling at 70% VO2peak until exhaustion. Whole-body peak power output (PPO) was assessed using an all-out 30-s sprint 17 min into each cycle stage. Ratings of perceived exertion (RPE) were recorded throughout. Isometric and isokinetic muscle-function tests were made between cycle stages, over ~6 min, and during 30-min recovery. Drop-jump measures were tested at exhaustion and during recovery.Results:PPO initially increased or was maintained in some subjects but fell to 81% of maximum at exhaustion. RPE was near maximal (18.7) at exhaustion, with the time to exhaustion related to the rate of rise of RPE. PPO first started to decline only when RPE exceeded 16 (ie, hard). Peak isometric and concentric isokinetic torque (180°/s) for the quadriceps fell to 86% and 83% of pretest at exhaustion, respectively. In contrast, the peak concentric isokinetic torque (180°/s) of the hamstrings increased by 10% before declining to 93% of maximum. Jump height fell to 92% of pretest at exhaustion and was correlated with the decline in PPO (r = .79). Muscle-function and jump-performance measures did not recover over the 30-min postexercise rest period.Conclusions:At exhaustion, whole-body power, muscle-function, and jump-performance measures had all fallen by 7–19%. PPO and drop-jump decrements were linearly correlated and are appropriate measures of maximal performance.


Author(s):  
Paola Gaeta ◽  
Jorge E. Viñuales ◽  
Salvatore Zappalà

This chapter discusses the fundamental principles governing international relations. The principles represent the fundamental set of standards on which States are united and which allow a degree of relatively smooth international dealings. They make up the apex of the whole body of international legislation. They constitute overriding legal standards that may be regarded as the constitutional principles of the international community. These principles are: the sovereign equality of States; the principle of non-intervention in internal affairs; the prohibition of the threat or use of force; peaceful settlement of international disputes; the duty to co-operate; the principle of good faith; self-determination of peoples; respect for human rights; and the prevention of significant environmental harm. The discussions then turn to the distinguishing traits of the fundamental principles and the close link between the principles and the need for their co-ordination.


2004 ◽  
Vol 132 (11-12) ◽  
pp. 409-413 ◽  
Author(s):  
Stanimir Stojiljkovic ◽  
Dejan Nesic ◽  
Sanja Mazic ◽  
Dejana Popovic ◽  
Dusan Mitrovic ◽  
...  

The objective of the study was to test the possibility of using the fixed value (12-13) of the Rating of Perceived scale (RPE scale), as a valid method for determination of ventilatory threshold (VT). The sample of the subjects included 32 physically active males (age: 22.3; TV: 180.5; TM: 75.5 kg; V02max: 57.1 mL/kg/min). During the continuous test of progressively increasing load on a treadmill, cardiorespiratory and other parameters were monitored using ECG and gas analyzer. Following the test, VT and V02max were determined. During the test, at each level, at the scale from 6 to 20, the subjects pointed the number that suited best their currently feeling of strain. The RPE threshold was defined as constant value of 12-13. Average values of ventilatory and RPE threshold were expressed by parameters that were monitored and then compared by using t-test for dependent samples. No significant difference was found between mean values of VT and RPE threshold, when they were expressed by relevant parameters: speed, load, heart rate, absolute and relative oxygen consumption. Fixed value (12-13) of RPE scale may be used to detect the exercise intensity that corresponds to ventilatory threshold.


1992 ◽  
Vol 36 (10) ◽  
pp. 712-716 ◽  
Author(s):  
Joseph M. Deeb ◽  
Colin G. Drury

This research was concerned with studying the development and growth of perceived effort of long-term isometric contractions as a function of muscle group (biceps vs quadriceps), of subjects with different age groups (20–29 vs. 50–59 years old) on long-term muscular isometric contractions (5 minutes) at different levels of %MVC (20, 40, 60, 80 and 100 %MVC). An experiment testing 20 subjects each performing 10 conditions (two muscle groups × five levels of %MVC) showed that the older age group reported Significantly higher perceived exertion at higher levels of %MVC and across time. Furthermore, subjects experienced a higher and faster increase in their perceived exertion when the level of %MVC and time increased.


1970 ◽  
Vol 09 (03) ◽  
pp. 259-267
Author(s):  
Akira Hasegawa ◽  
Goro Urakubo ◽  
Akira Tanaka

SummaryThe rapid synthesis of 203Hg-chlormerodrin by an isotopic exchange reaction in organic solvents was investigated using a mixture of inactive chlormerodrin and 203Hg-mercuric chloride. This reaction is promising as a practical method since 203Hg-CM can be so prepared in a short time. In methanol, 3-acetoxy-mercuri-2 methoxypropylurea exchanged at room temperature with 203Hg-mercuric acetate to a relatively high yield. The most suitable solvent for paper chromatography of CM was found to be a mixture of dimethylformamide, water and methanol (5 : 1 : 14 v/v). The fate and distribution of 203Hg-CM in rats were studied after a single oral dose and the maximum of activity was observed in the kidneys during the first 6 hours. A preferential binding of Hg by renal tissue was found. The biological half-life in the whole body was about 18.5 days. This compound was excreted mainly via the faeces but small amounts were excreted in the urine.


1989 ◽  
Vol 66 (1) ◽  
pp. 370-376 ◽  
Author(s):  
K. J. Motil ◽  
C. M. Montandon ◽  
D. L. Hachey ◽  
T. W. Boutton ◽  
P. D. Klein ◽  
...  

The adaptive responses of body protein metabolism to lactation were characterized in women at 1, 5, and 12 mo postpartum and in nulliparous controls during a controlled diet of measured protein and energy intakes by nitrogen balance, a constant infusion of [13C]bicarbonate, and a primed constant infusion of [1–13C]leucine and [alpha-15N]-lysine. Dietary energy intakes in the lactating women were 27% greater than those in the nulliparous controls. Despite these differences, lactating women had significantly lower nitrogen balances compared with the nonlactating women (-4.0 +/- 37.8 vs. +44.7 +/- 30.8 mg.kg-1.day-1). No significant differences in amino acid flux, oxidation, or incorporation into protein were detected during fasting conditions in the two groups of women. However, significantly positive associations were noted between dietary intakes and the variables of protein metabolism in the lactating women. A more complete understanding of the mechanisms that regulate the disposition of dietary nutrients into maternal body stores or milk production will enhance the determination of nutrient requirements in lactating women.


2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Chaofei Zhang ◽  
Wenjun Wang ◽  
Dennis Anderson ◽  
Sishu Guan ◽  
Guofa Li ◽  
...  

Stretch reflex is an important factor that influences the biomechanical response of the human body under whole-body vibration. However, there is a lack of quantitative evaluation at lower frequencies. Thus, the aim of this study was to investigate the effects of vibration on the stretch reflex and, in particular, to explore the quantitative relationship between dynamic muscle responses and low-frequency vibrations. The gastrocnemius muscle of 45 Sprague-Dawley rats was dissected. Sinusoidal vibrations of five discrete frequencies (2~16 Hz) with peak-to-peak amplitudes of 1 mm were applied to the gastrocnemius muscles with 2 mm or 3 mm prelengthening. Variables including dynamic muscle force, vibration acceleration, and displacement were recorded in two conditions, with and without the stretch reflex. Results showed that the dynamic muscle forces decreased by 20% on average for the 2 mm prelengthening group after the stretch reflex was blocked and by 24% for the 3 mm prelengthening group. Statistical analysis indicated that the amplitude of dynamic muscle force in the “with stretch reflex” condition was significantly larger than that in the “without stretch reflex” condition (p<0.001). The tension-length curve was found to be a nonlinear hysteresis loop that changed with frequency. The phase difference between the dynamic muscle force and the length change was affected significantly by vibration frequency (p<0.01), and the minimum frequency was 4–8 Hz. Experimental results of this study could benefit musculoskeletal model by providing a theoretical support to build a stretch reflex model for low-frequency vibration.


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