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Biomedical subjects

S J Legg

Publications and source records attributed to S J Legg.

18 recordsLinked to original sources
PubMed1992

The metabolic cost of backpack and shoulder load carriage.

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

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PubMed1988

Maximal aerobic capacity for repetitive lifting: comparison with three standard exercise testing modes.

A multi-stage, repetitive lifting maximal oxygen uptake (VO2max) test was developed to be used as an occupational research tool which would parallel standard ergometric VO2max testing procedures. The repetitive lifting VO2max test was administered to 18 men using an automatic repetitive lifting device. An intraclass reliability coefficient of 0.91 was obtained with data from repeated tests on seven subjects. Repetitive lifting VO2max test responses were compared to those for treadmill, cycle ergometer and arm crank ergometer. The mean +/- SD repetitive lifting VO2max of 3.20 +/- 0.42 l.min-1 was significantly (p less than 0.01) less than treadmill VO2max (delta = 0.92 l.min-1) and cycle ergometer VO2max (delta = 0.43 l.min-1) and significantly greater than arm crank ergometer VO2max (delta = 0.63 l.min-1). The correlation between repetitive lifting oxygen uptake and power output was r = 0.65. VO2max correlated highly among exercise modes, but maximum power output did not. The efficiency of repetitive lifting exercise was significantly greater than that for arm cranking and less than that for leg cycling. The repetitive lifting VO2max test has an important advantage over treadmill or cycle ergometer tests in the determination of relative repetitive lifting intensities. The individual curves of VO2 vs. power output established during the multi-stage lifting VO2max test can be used to accurately select work loads required to elicit given percentages of maximal oxygen uptake.

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PubMed1988

Effects of psychophysical lifting training on maximal repetitive lifting capacity.

The purpose of this investigation was to determine the effectiveness of psychophysical lifting training on maximal repetitive lifting capacity. Maximal repetitive lifting capacity was defined as the maximum box mass that could be lifted for 1 hr to a height of 132 cm at a rate of 6 lifts/min. Eight male subjects participated in five psychophysical lifting training sessions each week for 4 weeks. During each session subjects were presented with one empty and one heavily loaded box and asked to adjust the box mass to the maximum load they felt capable of lifting for 1 hr. This load was lifted at a rate of 6 lifts/min to a height of 132 cm for two 15-min periods each session. Heart rate was recorded, and subjects were asked to provide a rating of their perceived exertion. At the end of 4 weeks of training, subjects did not select a heavier training load, exhibit a decreased training heart rate, or report a decreased rating of perceived exertion. The training program did produce a significant increase in 1-hr maximal repetitive lifting capacity, as indicated by a greater box mass selected, but there was no concomitant change in VO2, heart rate, or rating of perceived exertion. It can be concluded that 4 weeks of psychophysical training of inexperienced lifters can produce a substantial increase in work output for a given energy expenditure. These increases are attributed to neural factors (skill, neuromuscular coordination) and to possible increases in the muscular endurance of specific muscle groups occurring with practice.

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PubMed1988

Prediction of the metabolic cost of exercise from measurements during recovery.

This study was designed to determine if post exercise recovery measurements could be used to predict oxygen uptake (VO2), minute ventilation (VE) and heart rates (HR) during exercise. VO2, VE and HR were measured in 11 healthy males during the last minute of treadmill running and during standing recovery. Since it is often impractical to collect data during the first 15 s of recovery in the field, the equations which best predicted the observed last-minute exercise values were obtained from enhanced linear least squares regressions of data collected between 15 and 60 s after cessation of exercise. In a separate validation experiment the mean (S.E.) difference between predicted and observed values for VO2, VE, and HR were 0.08 (0.06) L.min-1, 1.0 (5.1) L.min-1, and 2.2 (1.4) beats.min-1, respectively. We conclude that the equations described in this study may be used to estimate the metabolic cost of exercise in situations where it is impossible to make direct measurements.

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PubMed1987

Effects of sustained manual work and partial sleep deprivation on muscular strength and endurance.

In a military field artillery trial, the effects of 8 days of sustained manual work and partial sleep loss on isometric right hand grip strength and upper and lower body anaerobic power (using the Wingate test) was investigated in 25 healthy young male soldiers. During the trial, the physical activity of each subject was essentially identical except that an experimental group (n = 18) manually handled a large quantity of artillery shells (weighing 45 kg) and charges (13 kg), whilst a control group (n = 7) merely simulated manual handling activities and did no lifting or loading of shells. The daily amount of sleep obtained by each group was similar (3 to 4 hours), as were their activity patterns and food and fluid intake. Isometric right hand grip strength for both groups fell progressively during the trial and did not return to pre-trial levels during 3 days of recovery. At the end of the 8 day trial, there were statistically significant reductions in the body weight (1.9%, p less than 0.001), % body fat (7.1%, p less than 0.001) and upper body mean power (7.3%, p less than 0.01) of the experimental group but not in the controls. Lower body peak and mean power were significantly increased at the end of the trial in both the experimental (14.7%, p less than 0.001 and 17.0%, p less than 0.001 respectively) and control (14.3%, p less than 0.01 and 15.0%, p less than 0.05 respectively) groups. Lower body power decrease was significantly increased (18.1%, p less than 0.05) in the experimental group but not in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1987

Physiological ergonomics in nursing.

The majority of physiological ergonomic studies of nursing are concerned with shift- and night-work and associated circadian rhythm adjustments and influences on job performance. The aerobic demand of medical nursing has not been extensively studied. The aerobic capacity of nurses has not been assessed systematically. Studies of this type are clearly required within an ergonomic framework with particular emphasis on the flexibility and (upper body) strength components of nurses functional capacities in relation to the physical demands of nursing tasks. As health educators, the nursing profession should seriously consider taking a practical lead in espousing the ergonomic process and advocating the health benefits of exercise (together with good diet and smoking cessation.)

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PubMed1985

A comparison of the effects of mixed static and dynamic work with mainly dynamic work in hot conditions.

Current physiological criteria for limiting work in hot conditions are frequently based on responses to mainly dynamic work (eg treadmill walking). Their applicability to industrial situations containing mixed static and dynamic work is questioned, since the physiological responses to static work are different from those of dynamic work. Each of eight subjects attempted a one hour uphill treadmill walk (mainly dynamic work), and an uphill treadmill walk whilst intermittently carrying a 20 kg weight in the arms (mixed static and dynamic work). The external work rates in the two conditions were equal, effected by lowering the treadmill gradient in the loaded condition. Experiments were conducted in a hot climate (33 degrees C dry bulb, 25 degrees C wet bulb). Oxygen consumption, minute ventilation, sweat rate and rated perceived exertion were all significantly higher (p less than 0.001) for the mixed static and dynamic work than for the dynamic work. This was also the case for heart rate and forearm skin temperature (p less than 0.01), and for auditory canal temperature (p less than 0.05). There was no significant difference between the two types of work for mean skin temperature, calf skin temperature and chest skin temperature. These results show that for the same external work, physiological strain and perceived exertion are greater for mixed static and dynamic work (carrying a load in the arms) than for mainly dynamic work (walking on a treadmill). They suggest that it is not appropriate to make direct comparisons of laboratory studies based on dynamic work, with practical situations containing mixed static and dynamic work in the heat.

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