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Biomedical subjects

M G Maksud

Publications and source records attributed to M G Maksud.

At least 37 records · Page 2Linked to original sources
PubMed1977

Energy expenditure, productivity, and physical work capacity of sugarcane loaders.

VO2, E and heart rates (fH) were measured in 28 Colombian sugarcane loaders while loading cane and in the laboratory during a VO2max test. Productivity (metric tons-day-1) of the workers was also obtained. During work, VO2 was 1.251-min-1, VE 38.81 min-1, and fH 120 beats-min-1. The subjects worked at 42% of VO2max (6.3 +/- 1.0 kcal-min-1) during the field measurement periods. Energy expenditure was estimated to average 3,281 kcal-24 hr-1. Productivity was higher in men with lower fat content, resting fH and fH at VO2 = 1.25 1-min-1, indicating a positive relationship between productivity and physical fitness. Productivity was not related to age but, since VO2max decreased with age, the relative effort required to maintain productivity increased in the older workers. Efficiency (kg cane loaded-1 VO2-1) and estimated sustained effort (percent VO2max) were not significantly correlated with productivity in this type of discontinuous, moderate work.

Age Factors↗
PubMed1977

Productivity and maximal oxygen consumption in sugar cane cutters.

Vo2max and daily productivity (metric tons/day) have been measured in 46 sugar cane cutters 18 to 34 years of age. A multiple regression analysis demonstrated that productivity was simultaneously related to VO2max, height and body fat (r=0.685;P less than 0.001). The multiple regression equation was: productivity (tons/day)=0.81 VO2max-0.14 percent fat +0.03 height -1.96. The data indicate that productivity is affected indirectly by nutritional status through the influence of the latter on height, fat content and VO2max. The decrease in VO2max that occurs with age was similar to that reported in the literature. Evidence is presented that, as the worker ages, a higher percent VO2max has to be utilized to maintain productivity.

Adolescent↗
PubMed1977

Effect of dietary protein restriction or food restriction on oxygen consumption and mitochondrial distribution in cardiac and red and white skeletal muscle of rats.

The effects of food restriction and dietary protein restriction on the oxygen consumption of three types of muscle in the rat were compared. Control rats were fed a diet containing 27% casein. Two groups of protein-restricted rats were fed isoenergy diets containing 15% or 8% casein. Two groups of food-restricted rats were fed either the 27% or 15% casein diets in amounts equivalent to 35% of the intake of energy. Oxygen consumption was measured in papillary muscle and in fibers from the red (high oxidative) and white (low oxidative) portions of the quadriceps with pyruvate and malate as substrates. Control values (micronlO2/g dry wt/min) were 35.2 + 1.5 (papillary), 20.7+/-1.9 (red), and 7.8+/-0.7 (white). Restriction of dietary protein content failed to alter the oxygen consumption of any of the muscle types. In contrast, involuntary food restriction,combined with a reduction in protein content, caused a reduction in the oxygen consumption of papilary and white skeletal muscle, but the metabolism of red skeletal muscle was not affected. No differences were found in the appearance and distribution of mitochondria in cardiac or red skeletal muscle after examination by electron microscopy, but a depletion of subsarcolemmal mitochondria was evident in white muscle from the food-restricted rats.

Animals↗
PubMed1977

Efficiency and daily work effort in sugar cane cutters.

Productivity (metric tons (tonnes)/day), efficiency (kg cane cut/litre Vo2), and effort (percent Vo2 max sustained during an 8-hour workday) have been measured in 54 Colombian sugar cane cutters. In workers who sustained less than 40% Vo2 max during the workday, the effort expended was related to productivity (4 = 0-71) but efficiency and productivity were not significantly correlated. In 16 workers sustaining a greater than 40% Vo2 max during the workday, productivity and effort were not related and efficiency was significantly reduced. Subjects using less than 40% Vo2 max were divided into good, average and poor producers and compared with the men with low efficiencies. In general, these inefficient men had the anthropometric and physical fitness characteristics of low productivity workers (smaller stature, weight and Vo2 max). However, the frequency of good, average, and poor cutters in the inefficient group did not differ from that of the men expending less than 40% of their maximum effort nor was their average productivity different. No obvious reasons for the differences in efficiency and effort of these men were found.

Adult↗
PubMed1977

Influence of chronic undernutrition on oxygen consumption of rats during exercise.

Endurance swimming times and oxygen comsumption during strenuous exercise were measured in age-paired undernourished rats. The animals received restricted or unrestricted amounts of 27, 15 or 8% casein diets for 10 weeks. Endurance times of energy-restricted animals were similar to that of controls, despite a two-fold weight difference. Endurance time of the protein-restricted group (8% casein) was longer than that of any other group, including energy-restricted groups identical in weight. Oxygen consumption of the protein-restricted group during a non-endurance swim was significantly greater than any of the other groups, but was the same as that of the other undernourished groups during the endurance swin. Oxygen consumption by all undernourished groups was higher than that of controls during the endurance swim. Results of the endurance swimming tests show that restriction of protein or energy intake may influence exercise performance differently and that differences in work performance cannot be explained by differences in body weight. Measurements of oxygen consumption during swimming suggests that the differences in performance are related to altered metabolic requirements resulting from the dietary restrictions.

Animals↗
PubMed1976

The aerobic power of several groups of laborers in Colombia and the United States.

Physiological responses to exercise and anthropometry were measured in several groups of physical laborers. The groups included Colombian sugar cane cutters, sugar cane loaders and general farm laborers. In addition, migrant workers and civil service laborers from the United States were studied. The Colombian populations were generally shorter, weighed less and had less body fat than the United States group. The nutritional state of the Colombian groups, as measured by the hematocrit, hemoglobin, serum albumin and total blood protein, appeared normal. The aerobic power of the Colombia populations was significantly larger than the United States groups. The larger aerobic power of the Colombian groups is probably related to greater physical fitness associated with the physical demands of their occupations.

Adult↗
PubMed1976

Metabolic changes in exercise-induced and methacholine-induced bronchoconstriction.

Metabolic and physiological responses to graded exercise and methacholine challenge were investigated in asthmatics with or without exercise-induced bronchoconstriction. The results showed that after methacholine challenge, free fatty acid levels increased only in patients with exercise-induced asthma, while they increased in both groups of asthmatics after treadmill exercise. No significant changes were noted in plasma lactic acid levels, ventilation, or oxygen consumption among the groups studied. These data suggest that asthmatics with exercise-induced bronchoconstriction may differ from other asthmatics in some of their metabolic responses.

Adolescent↗
PubMed1975

Energy expenditure cutting supercane.

VO2 VE, and heart rates (fH) were measured in 61 Colombian sugarcane cutters while harvesting cane in the AM and PM and in the laboratory during a VO2max test. Productivity and sweat rates were also measured in the field. The subjects had an estimated dietary intake of 2,970 kcal/day, which was lower than calculated daily energy expenditure. During the work measurements the VO2 was 1.5 1/min, VE 48 1/min, and fH 135 beats/min; there were no differences between AM and PM values. The subjects sustained about 35% of VO2max during the 8 h workday, but worked at 57% of VO2max during the tests. Measured energy cost was 7.4 +/- 1.5 kcal/min during the workday. Sweat rates were higher PM than AM (5 KG/8 h day). Grouping of the men according to productivity demonstrated that taller, heavier men were better producers and had lower calculated heart rates at VO2 1.51/min. Efficiency of cane cutting was higher (9%) PM.

Adult↗