Oxygen transport during exercise in human subjects

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    • "Other studies in the same population reported a noticeable decrease of maximum aerobic capacity after 33 years of age both for industrial workers and porters as well [8, 9]. Hermansen [24] depicted that maximal oxygen uptake increased almost rectilinearly from the age of 11 to the age of 16 years in males wherefrom it increased at a lower rate reaching a peak value at an age of approximate 25 years. Thereafter, a steady gradual decrease of it was observed. "
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    ABSTRACT: Miners fitness test was assessed in terms of determination of maximum aerobic capacity by an indirect method following a standard step test protocol before going down to mine by taking into consideration of heart rates (Telemetric recording) and oxygen consumption of the subjects (Oxylog-II) during exercise at different working rates. Maximal heart rate was derived as 220−age. Coal miners reported a maximum aerobic capacity within a range of 35–38.3 mL/kg/min. It also revealed that oldest miners (50–59 yrs) had a lowest maximal oxygen uptake (34.2 ± 3.38 mL/kg/min) compared to (42.4 ± 2.03 mL/kg/min) compared to (42.4 ± 2.03 mL/kg/min) the youngest group (20–29 yrs). It was found to be negatively correlated with age (r = −0.55 and −0.33 for younger and older groups respectively) and directly associated with the body weight of the subjects (r = 0.57 – 0.68, P ≤ 0.001). Carriers showed maximum cardio respiratory capacity compared to other miners. Indian miners VO2max was found to be lower both compared to their abroad mining counterparts and various other non-mining occupational working groups in India.
    Journal of Environmental and Public Health 09/2011; 2011:232168. DOI:10.1155/2011/232168
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    • "whole body exercise, than in running , but the difference is small. The slightly higher oxygen uptake is most likely explained by an enlarged oxygen extraction in the periphery and not by a larger stroke volume and cardiac output (Hermansen, 1973). "
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    ABSTRACT: Cross-country skiing is one of the most demanding endurance sports. It im-poses extensive physiological challenges due to the perpetual changes be-tween, and utilisation of, different skiing techniques, each involving the upper and lower body to various extents. Altogether, the uniqueness of the sport has over the years contributed to significant interest from physiologists in their ongoing ambition to understand more about the human engine. Oxygen uptake Hill and his colleagues were pioneers in the discussion of the major links in the chain for transport of oxygen in humans, discussing potential limiting factors (Hill et al., 1924). Since then, several studies have reported improvement in maximal oxygen uptake (VO2 max) after endurance training (for refs see Mitchell & Saltin, 2003). Several factors contributes to this increase; 1) an increased cardiac output, 2) an optimal distribution of the blood to the most active muscles and minimising the blood flow to the non-active tissues and organs, and 3) greater extraction of the delivered oxygen. It has been pro-posed that maximal oxygen uptake is not limited by one specific link, rather it is determined by a close integrated interaction between all the links in the oxy-gen transport chain (Di Prampero, 1985; Wagner et al., 1997). Among these, the capacity of the cardiovascular system to deliver oxygen to the skeletal muscles, i.e. cardiac output and blood flow, is considered to be the most im-portant limiting factor (Mitchell et al., 1958; Ekblom & Hermansen, 1968; Di Prampero, 1985; Saltin & Strange, 1992). Numerous studies have documented that successful cross-country skiers have exceptionally high aerobic power, both in absolute and relative values (Strømme et al., 1977; Rusko, 1992; Holmberg et al., 2007). Few male skiers have won medals in a major championship without having maximal oxygen
    Science and Skiing IV, Edited by Erich (EDT) Mueller, Stefan (EDT) Lindinger, Thomas (EDT) Stogg, 01/2009: chapter The competitive Cross-Country Skier - an impressive human engine: pages 101-109; Meyer Meyer Sport (UK) Ltd., ISBN: 9781841262550
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    • "Diversely, in TM walking, at each step, mechanical work is performed involving a large number of body segments to cyclically raise and accelerate the body's centre of mass, so that the subject's own weight becomes an important load. Moreover, a different cardiovascular response is reported for TM and CE exercise in normal weight individuals (Hermansen et al. 1970; Faulkner et al. 1971; Hermansen, 1973; Hilloskorpi et al. 1999), which means that the heart rate is higher on the CE than on the TM, for the same submaximal energy expenditure. Unfortunately, to our knowledge, no comparative study in obese individuals, concerning the energetic cost of physical activity and the cardiovascular response with these two modalities of exercise, is presently available. "
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    ABSTRACT: Physical activity is essential in obesity management, but exercise capacity is compromised in obese individuals due to the excessive body mass, impacting on body movement's energetics, and to the dysfunctions of regulatory mechanisms, affecting cardiovascular responses. This study aims to compare the energetics and cardiovascular responses of walking and cycling in obese women, and to formulate recommendations regarding the most suitable type of exercise for obesity. Fifteen obese (OB) and six normal weight (NW) women exercised on treadmill (TM) and cycle ergometer (CE). During both exercise modalities, metabolic rate was higher in OB than in NW and correlated with measures of body mass. Leg movement metabolic rate during cycling depended upon individual adiposity, and when accounted for, mechanical efficiency was similar in the two groups. When accounting for extra mass, differences in metabolic rate among groups are abolished for CE, indicating no obesity impairment of muscle efficiency, but not for TM, suggesting that differences in biomechanics may explain the higher net cost of transport of OB. In both groups, HR was higher during CE than TM at the same oxygen uptake (VO(2)), but in OB the HR increment over VO(2) was greater for CE than for TM. Therefore, due to different cardiovascular responses to TM and CE in OB, walking is more convenient, enabling OB to attain target energy expenditure at lower HR or in a shorter time.
    Arbeitsphysiologie 09/2008; 103(6):707-17. DOI:10.1007/s00421-008-0758-y · 2.19 Impact Factor
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