Home About us Contact
|
Home About us Contact | ||
|
|
||
Maximal Oxygen Consumption (maximal + oxygen_consumption)
Selected AbstractsRelationship between Relative Aerobic Power and Echocardiographic Characteristics in Male AthletesECHOCARDIOGRAPHY, Issue 9 2007Zsuzsanna Kneffel M.Ed. The relationship between relative aerobic power (rel.VO2max) as a generally accepted indicator of endurance capacity and certain characteristics of the athlete's heart, such as body-size related (relative) left ventricular (LV) diastolic wall thickness (WTd), internal diameter (LVIDd), muscle mass (MM), WTd/IDd, heart rate (HR), fractional shortening (FS) and E/A ratio, were investigated in 346 young males (18,35 years, 291 athletes of various events and 55 nonathletic control subjects). Rel.VO2max was measured by spiroergometry; cardiac characteristics were determined by two-dimensionally guided M-mode and Doppler-echocardiography. When the groups were pooled, correlation of rel.VO2max with the cardiac parameters was significant: LVMM·BSA,1.5= 0.413, LVWTd·BSA,0.5= 0.327, LVIDd·BSA,0.5= 0.292, HR =,0.434, E/A = 0.272 (P < 0.001), but no significant relationship was seen with FS and WTd/IDd. In the endurance trained group, rel. VO2max correlated significantly with LVMM·BSA,1.5, LVWT·BSA,0.5, HR, and E/A, in the ballgame players with LVMM·BSA,1.5, LVWT·BSA,0.5, and E/A, in the power-and-sprint event athletes with HR and E/A. In the control group, no significant relationship was observed. Results indicate that in athletes having higher endurance capacity maximal oxygen consumption depends largely on cardiac condition, while in athletes with a lower endurance capacity it can be limited by peripheral conditions. [source] Pharmacokinetics of detomidine administered to horses at rest and after maximal exerciseEQUINE VETERINARY JOURNAL, Issue 5 2009J. A. E. HUBBELL Summary Reason for performing study: Increased doses of detomidine are required to produce sedation in horses after maximal exercise compared to calm or resting horses. Objectives: To determine if the pharmacokinetics of detomidine in Thoroughbred horses are different when the drug is given during recuperation from a brief period of maximal exercise compared to administration at rest. Methods: Six Thoroughbred horses were preconditioned by exercising them on a treadmill. Each horse ran a simulated race at a treadmill speed that caused it to exercise at 120% of its maximal oxygen consumption. One minute after the end of exercise, horses were treated with detomidine. Each horse was treated with the same dose of detomidine on a second occasion a minimum of 14 days later while standing in a stocks. Samples of heparinised blood were obtained at various time points on both occasions. Plasma detomidine concentrations were determined by liquid chromatographymass spectrometry. The plasma concentration vs. time data were analysed by nonlinear regression analysis. Results: Median back-extrapolated time zero plasma concentration was significantly lower and median plasma half-life and median mean residence time were significantly longer when detomidine was administered after exercise compared to administration at rest. Median volume of distribution was significantly higher after exercise but median plasma clearance was not different between the 2 administrations. Conclusions and potential relevance: Detomidine i.v. is more widely distributed when administered to horses immediately after exercise compared to administration at rest resulting in lower peak plasma concentrations and a slower rate of elimination. The dose requirement to produce an equivalent effect may be higher in horses after exercise than in resting horses and less frequent subsequent doses may be required to produce a sustained effect. [source] Exercise training in late middle-aged male Fischer 344 × Brown Norway F1-hybrid rats improves skeletal muscle aerobic functionEXPERIMENTAL PHYSIOLOGY, Issue 7 2008Andrew C. Betik The Fischer 344 × Brown Norway F1-hybrid (F344BN) rat has become an increasingly popular and useful strain for studying age-related declines in skeletal muscle function because this strain lives long enough to experience significant declines in muscle mass. Since exercise is often considered a mechanism to combat age-related declines in muscle function, determining the utility of this strain of rat for studying the effects of exercise on the ageing process is necessary. The purpose of this study was to evaluate the plasticity of skeletal muscle aerobic function in late middle-aged male rats following 7 weeks of treadmill exercise training. Training consisted of 60 min per day, 5 days per week with velocity gradually increasing over the training period according to the capabilities of individual rats. The final 3 weeks involved 2 min high-intensity intervals to increase the training stimulus. We used in situ skeletal muscle aerobic metabolic responses and in vitro assessment of muscle mitochondrial oxidative capacity to describe the adaptations of aerobic function from the training. Training increased running endurance from 11.3 ± 0.6 to 15.5 ± 0.8 min, an improvement of ,60%. Similarly, distal hindlimb muscles from trained rats exhibited a higher maximal oxygen consumption in situ (23.2 ± 1.3 versus 19.7 ± 0.8 ,mol min,1 for trained versus sedentary rats, respectively) and greater citrate synthase and complex IV enzyme activities in gastrocnemius (29 and 19%, respectively) and plantaris muscles (24 and 28%, respectively) compared with age-matched sedentary control animals. Our results demonstrate that skeletal muscles from late middle-aged rats adapt to treadmill exercise by improving skeletal muscle aerobic function and mitochondrial enzyme activities. This rat strain seems suitable for further investigations using exercise as an intervention to combat ageing-related declines of skeletal muscle aerobic function. [source] Endurance exercise performance: the physiology of championsTHE JOURNAL OF PHYSIOLOGY, Issue 1 2008Michael J. Joyner Efforts to understand human physiology through the study of champion athletes and record performances have been ongoing for about a century. For endurance sports three main factors , maximal oxygen consumption , the so-called ,lactate threshold' and efficiency (i.e. the oxygen cost to generate a give running speed or cycling power output) , appear to play key roles in endurance performance. and lactate threshold interact to determine the ,performance , which is the oxygen consumption that can be sustained for a given period of time. Efficiency interacts with the performance to establish the speed or power that can be generated at this oxygen consumption. This review focuses on what is currently known about how these factors interact, their utility as predictors of elite performance, and areas where there is relatively less information to guide current thinking. In this context, definitive ideas about the physiological determinants of running and cycling efficiency is relatively lacking in comparison with and the lactate threshold, and there is surprisingly limited and clear information about the genetic factors that might pre-dispose for elite performance. It should also be cautioned that complex motivational and sociological factors also play important roles in who does or does not become a champion and these factors go far beyond simple physiological explanations. Therefore, the performance of elite athletes is likely to defy the types of easy explanations sought by scientific reductionism and remain an important puzzle for those interested in physiological integration well into the future. [source] Metabolic and cardiopulmonary effects of detraining after a structured exercise training programme in young PCOS womenCLINICAL ENDOCRINOLOGY, Issue 6 2008Francesco Orio Summary Objective The aim of the present study was to determine if the favourable cardiopulmonary and metabolic benefits induced by exercise training (ET) programme are maintained after its cessation. Patients Thirty-two young overweight polycystic ovary syndrome (PCOS) women matched for age and body mass index (BMI) with other 32 PCOS patients was enrolled. The first group [PCOS-T (trained)] underwent 24-week ET programme, whereas the second [PCOS-DT (detrained)] underwent 12-week ET programme followed by 12-week detraining period. Methods At baseline, after 12- and 24-week follow-up, all PCOS women were studied for their hormonal (ovarian and adrenal androgens), metabolic (glucose and insulin) and lipid profile, and underwent cardiopulmonary exercise test. Results After the initial 12-week ET programme, both PCOS-T and PCOS-DT groups, without differences between groups, showed a similar significant (P < 0·05) improvement in BMI, fasting insulin, areas under curve insulin (AUCINS), glucose and insulin AUC (AUCGLU/INS), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) and maximal oxygen consumption at cardiopulmonary exercise test (VO2max). At 24-week follow-up, PCOS-T group showed a significant (P < 0·05) improvement in BMI, fasting insulin, AUCINS, AUCGLU/INS, LDL-C, HDL-C and VO2max, in comparison to baseline and 12-week follow-up. At same follow-up visit, the all parameters resulted significantly (P < 0·05) worsened in PCOS-DT group in comparison to 12-week follow-up and PCOS-T group. In PCOS-DT group, no parameter assessed at 24-week follow-up was significantly different in comparison with baseline. Conclusion In young PCOS women, 12-week detraining resulted in a complete loss of the favourable adaptations obtained after ET. [source] | |||||||||||||