Search PubMed⌕ Search

Biomedical subjects

D G Jenkins

Publications and source records attributed to D G Jenkins.

At least 37 records · Page 2Linked to original sources
PubMed1998

The effect of stage duration on the calculation of peak VO2 during cycle ergometry.

This study investigated the influence of stage duration on the calculation of peak oxygen consumption (peak VO2 to determine whether both the lactate threshold (LT) and peak VO2 could be measured during the same test without compromising the peak VO2 value obtained. Eight moderately-active females (mean age +/- SD = 19.6 +/- 2.5 years) performed three peak VO2 tests on an electrically-braked cycle ergometer. Power output was increased every minute for the short peak VO2 test (S) and every three minutes for the long peak VO2 tests (L). Testing took place over two weeks with all tests separated by at least 48 hours. The first peak VO2 test was a long test (L1) and served as familiarisation. The subjects then performed a short (S) and a long (L2) peak VO2 test in random, counterbalanced order. For each subject, all three tests were performed at the same time of day in controlled environmental conditions. There was no significant difference between the two exercise protocols for peak VO2 when expressed in ml x kg(-1) x min(-1) (F[1,7]=3.47, P=0.105) or in L x min(-1) (F[1,7]=3.39. P=0.108). However, the maximum heart rate (HRmax) achieved in S was significantly less than the HRmax achieved in L2 (F[1,7]=33.4, P<0.001). The power output at exhaustion (Wpeak) was significantly greater in S than in L2 (F[1,7]=56.5, P<0.001). The data from this study therefore showed that in moderately-active females, a three-minute incremental protocol, allowing for the simultaneous calculation of the LT, could be used without compromising peak VO2, but that HRmax and Wpeak were affected.

Adolescent↗
PubMed1998

The critical power function is dependent on the duration of the predictive exercise tests chosen.

The linear relationship between work accomplished (W(lim)) and time to exhaustion (t(lim)) can be described by the equation: W(lim) = a + CP x t(lim). Critical power (CP) is the slope of this line and is thought to represent a maximum rate of ATP synthesis without exhaustion, presumably an inherent characteristic of the aerobic energy system. The present investigation determined whether the choice of predictive tests would elicit significant differences in the estimated CP. Ten female physical education students completed, in random order and on consecutive days, five all-out predictive tests at preselected constant-power outputs. Predictive tests were performed on an electrically-braked cycle ergometer and power loadings were individually chosen so as to induce fatigue within approximately 1-10 mins. CP was derived by fitting the linear W(lim)-t(lim) regression and calculated three ways: 1) using the first, third and fifth W(lim)-t(lim) coordinates (I135), 2) using coordinates from the three highest power outputs (I123; mean t(lim) = 68-193 s) and 3) using coordinates from the lowest power outputs (I345; mean t(lim) = 193-485 s). Repeated measures ANOVA revealed that CPI123 (201.0+/-37.9W) > CPI135 (176.1+/-27.6W) > CPI345 (164.0+/-22.8W) (P<0.05). When the three sets of data were used to fit the hyperbolic Power-t(lim) regression, statistically significant differences between each CP were also found (P<0.05). The shorter the predictive trials, the greater the slope of the W(lim)-t(lim) regression; possibly because of the greater influence of 'aerobic inertia' on these trials. This may explain why CP has failed to represent a maximal, sustainable work rate. The present findings suggest that if CP is to represent the highest power output that an individual can maintain "for a very long time without fatigue" then CP should be calculated over a range of predictive tests in which the influence of aerobic inertia is minimised.

Adenosine Triphosphate↗
PubMed1998

Anthropometric-based selection and sprint kayak training in children.

A 12 week kayak training programme was evaluated in children who either had or did not have the anthropometric characteristics identified as being unique to senior elite sprint kayakers. Altogether, 234 male and female school children were screened to select 10 children with and 10 children without the identified key anthropometric characteristics. Before and after training, the children completed an all-out 2 min kayak ergometer simulation test; measures of oxygen consumption, plasma lactate and total work accomplished were recorded. In addition, a 500 m time trial was performed at weeks 3 and 12. The coaches were unaware which 20 children possessed those anthropometric characteristics deemed to favour development of kayak ability. All children improved in both the 2 min ergometer simulation test and 500 m time trial. However, boys who were selected according to favourable anthropometric characteristics showed greater improvement than those without such characteristics in the 2 min ergometer test only. In summary, in a small group of children selected according to anthropometric data unique to elite adult kayakers, 12 weeks of intensive kayak training did not influence the rate of improvement of on-water sprint kayak performance.

Adult↗
PubMed1998

The relationship between plasma lactate parameters, Wpeak and 1-h cycling performance in women.

PURPOSE: The relationship between six descriptors of lactate increase, peak VO2, Wpeak, and 1-h cycling performance were compared in 24 trained, female cyclists (peak VO(2) = 48.11 +/- 6.32 mLxkg(-1)xmin(-1). METHODS: The six descriptors of lactate increase were: 1) lactate threshold (LT; the power output at which plasma lactate concentration begins to increase above the resting level during an incremental exercise test), 2) LT(1) the power output at which plasma lactate increases by 1 mM or more), 3) LT(D) (the lactate threshold calculated by the D-max method), 4) LT(MOD) (the lactate threshold calculated by a modified D-max method), 5) L4 (the power output at which plasma lactate reaches a concentration of 4 mmolxL(-1), and 6) LT(LOG) (the power output at which plasma lactate concentration begins to increase when the log ([La(-1]) is plotted against the log (power output). Subjects first completed a peak VO(2) test on a cycle ergometer. Finger-tip capillary blood was sampled within 30 s of the end of each 3-min stage for analysis of plasma lactate. Endurance performance was assessed 7 d later using a 1-h cycle test (OHT) in which subjects were directed to achieve the highest possible average power output. RESULTS: The mean power output (W) for the OHT (+/- SD) was 183.01 +/- 18.88, and for each lactate variable was:LT (138.54 +/- 46.61), LT(1) (179.17 +/- 27.25), LT(log) (143.97 +/- 45.74), L4 (198.09 +/- 33.84), LT(D) (178.79 +/- 24.07), LT(MOD)(212.28 +/- 31.75). Average power output during the OHT was more strongly correlated with all plasma lactate parameters (0.61<r<0.84) and W(peak) (r = 0.81) than with peak VO(2) (r = 0.55). The six lactate parameters were strongly correlated with each other (0.54<r<0.91) and of six lactate parameters, LT(D) correlated best with endurance performance (r = 0.84). CONCLUSIONS: It was concluded that plasma lactate parameters and W(peak) provide better indices of endurance performance than peak VO(2) and that, of the six descriptors of lactate increase measured in this study, LT(D) is most strongly related to 1-h cycling performance in trained, female cyclists.

Adult↗
PubMed1998

Muscle metabolites and performance during high-intensity, intermittent exercise.

Six men were studied during four 30-s "all-out" exercise bouts on an air-braked cycle ergometer. The first three exercise bouts were separated by 4 min of passive recovery; after the third bout, subjects rested for 4 min, exercised for 30 min at 30-35% peak O2 consumption, and rested for a further 60 min before completing the fourth exercise bout. Peak power and total work were reduced (P < 0. 05) during bout 3 [765 +/- 60 (SE) W; 15.8 +/- 1.0 kJ] compared with bout 1 (1,168 +/- 55 W, 23.8 +/- 1.2 kJ), but no difference in exercise performance was observed between bouts 1 and 4 (1,094 +/- 64 W, 23.2 +/- 1.4 kJ). Before bout 3, muscle ATP, creatine phosphate (CP), glycogen, pH, and sarcoplasmic reticulum (SR) Ca2+ uptake were reduced, while muscle lactate and inosine 5'-monophosphate were increased. Muscle ATP and glycogen before bout 4 remained lower than values before bout 1 (P < 0.05), but there were no differences in muscle inosine 5'-monophosphate, lactate, pH, and SR Ca2+ uptake. Muscle CP levels before bout 4 had increased above resting levels. Consistent with the decline in muscle ATP were increases in hypoxanthine and inosine before bouts 3 and 4. The decline in exercise performance does not appear to be related to a reduction in muscle glycogen. Instead, it may be caused by reduced CP availability, increased H+ concentration, impairment in SR function, or some other fatigue-inducing agent.

Adenosine Triphosphate↗
PubMed1997

The relationship between plasma potassium concentration and muscle torque during recovery following intense exercise.

The present study investigated the relationship between plasma potassium ion concentration ([K+]) and skeletal muscle torque during three different 15-min recovery periods after fatigue induced by four 30-s sprints. Four males and one female completed the multiple sprint exercise on three separate days; recovery was passive, i.e. no cycling exercise (PRec), active cycling at 30% peak oxygen consumption. VO2peak (30% Rec) and active cycling at 60% VO2peak (60% Rec). Plasma [K+] was measured from blood sampled from an antecubital vein of subjects at rest and at 0, 3, 5, 10 and 15 min into each recovery. Isokinetic leg strength was measured at rest and at 1, 6, 11 and 16 min during each recovery. Following the exhaustive sprints, [K+] increased significantly from an average mean (SEM) resting value of 3.81 (0.07) mmol.l-1 to 4.48 (0.19) mmol.l-1 (P < 0.01). In all recovery conditions, plasma [K+] returned to resting levels within 3 min following the fourth sprint. However, in the two active recovery conditions plasma [K+] increased over the remainder of the recovery periods to 4.36 (0.12) mmol.l-1 in the 30% Rec condition and 4.62 (0.12) mmol.l-1 in the 60% Rec condition, the latter being significantly higher than the former (P < 0.01). The maximum torque measured following the sprints decreased significantly, on average, to 61.1 (8.36)% of peak levels (P < 0.01). After 15 min of recovery, maximum torque was highest in the 30% Rec condition at 92.13 (3.06)% of peak levels (P < 0.01), compared to 85.23 (3.64)% and 85.71 (0.82)% for the PRec and 60% Rec conditions, respectively. In contrast to the significant differences in plasma [K+] across all three recovery conditions, muscle torque recovery was significantly different in only the 30% Rec condition. In summary, recovery of peak levels of muscle torque following fatiguing exercise does not appear to follow changes in plasma [K+].

Adult↗
PubMed1997

Ramp and constant power trials produce equivalent critical power estimates.

The standard critical power test protocol on the cycle ergometer prescribes a series of trials to exhaustion, each at a different but constant power setting. Recently the protocol has been modified and applied to a series of trials to exhaustion each at a different ramp incremental rate. This study was undertaken to compare critical power and anaerobic work capacity estimates in the same group of subjects when derived from the two protocols. Ten male subjects of mixed athletic ability cycled to exhaustion on eight occasions in randomized order over a 3-wk period. Four trials were performed at differing constant power settings and four trials on differing ramp incremental rates. Both critical power and anaerobic work capacity were estimated for each subject by curve fitting of the ramp model and of three versions of the constant power model. After adjusting for inter-subject variability, no significant differences were detected between critical power estimates or between anaerobic work capacity estimates from any model formulation or from the two protocols. It is concluded that both the ramp and constant power protocols produce equivalent estimates for critical power and anaerobic work capacity.

Adult↗
PubMed1996

Relationship between gear ratio and 10-s sprint cycling on an air-braked ergometer.

This investigation examined the relationship between gear ratio and peak and mean power outputs (PPO and MPO) and peak cadence (PC) during a 10-s all-out sprint on a multi-geared air-braked cycle ergometer. Ten physically active men [mean age 21.0 years (SEM 0.7)] performed in random order six 10-s sprints (15-min rest between each sprint) on two occasions (48 h apart) in six different gear ratios; flywheel revolutions per pedal crank revolution (FR/PCR) ranged between 5.22 and 11.61. The PPO, MPO, and PC were recorded from each sprint. Of the six gear ratios tested, a gear ratio eliciting 8.87 FR/PCR elicited the highest PPO for the initial test session; the PPO output of 1274 W was significantly greater (P < 0.01) than that produced in the other five gears. Analysis of data from the second test session revealed no statistically significant difference in PPO between gear ratios eliciting 8.00, 8.87, and 10.06 FR/PCR. The PPO from these three ratios were significantly greater (P < 0.05) than those produced using the ratios resulting in 6.32, 7.06, and 10.78 FR/PCR. The PC in the gear ratio maximising PPO was 120 rpm. Analysis of PC data revealed a significant decrease (P < 0.05) as the number of FR/PCR increased.

Adult↗
PubMed1996

Effects of oral creatine supplementation on multiple sprint cycle performance.

This study examined the influence of oral creatine monohydrate supplementation on repeated 10 s cycle ergometer sprint performance. Seventeen recreationally active males (mean +/- SD age, body mass, height, and peak oxygen uptake = 20.5 +/- 1.2 yr, 72.1 +/- 10.3 kg, 176.8 +/- 6.6 cm and 3.87 +/- 0.91 l.min-1, respectively) participated in the 16 day experiment. All subjects initially completed a VO2peak test and were then administered glucose (4 x 10 g per day) in a single blind fashion for four days, after which they completed the first series of multiple sprints (7 x 10 s). Following the sprints, subjects were matched on sprint performance and divided into two groups (n = 8, placebo (Pl); and n = 9, creatine (Cr)). For the following four days, diets were supplemented with either Cr (4 x 70 mg.kg-1 body mass per day mixed with 5 g glucose) or glucose (4 x 10 g per day); supplementation during this phase was double-blind. Subjects then repeated the multiple sprint and VO2peak tests. Measures of peak power output (PPO), mean power output (MPO), end-power output (EPO), and percent power decline were recorded during the sprints. Each 10 s sprint was separated by 30 s of passive recovery except for sprints five and six which were separated by five minutes. Venous blood was sampled at rest, immediately after sprint five, before sprint six, and following sprint seven for the analysis of plasma lactate and blood pH. Expired air was sampled for five minutes following sprint seven for the calculation of post-exercise VO2. Analysis of variance revealed that four days of Cr supplementation did not influence multiple sprint performance, plasma lactate, blood pH and excess post-sprint oxygen consumption. Furthermore, VO2peak was unchanged following Cr supplementation. The data suggest that either the four day period of Cr supplementation failed to significantly raise resting muscle [Cr], or that multiple sprint performance was not enhanced by increases in resting muscle [Cr].

Adult↗
PubMed1996

The influence of resistance training on the critical power function & time to fatigue at critical power.

The present study examined whether a six-week resistance training program would influence the critical power (CP) function, time to exhaustion (TE) at CP and/or peak oxygen uptake (VO2 peak). The CP function is believed to provide an index of endurance ability (CP given by the slope), and anaerobic work capacity (the y-intercept). Eight healthy, untrained males undertook lower-body resistance training (90 min/day, 3-4 times/wk) for six weeks; eight controls refrained from resistance or endurance training for the same period. Before and immediately following the training period, subjects completed three trials to determine their CP function, a test of VO2 peak, a one-repetition maximum (1-RM) leg press test and TE at their CP. Training significantly increased both 1-RM leg press (28.6%, P < 0.05) and the y-intercept (34.9%, P < 0.05) while no changes in CP, VO2 peak or TE (p > 0.05) were found. Changes in the y-intercept following resistance training were negatively correlated with changes in the CP (r = -0.94, p < 0.05, N = 8). The present data show that the y-intercept of the CP function is sensitive to, and modified by, six weeks of resistance training. Given that resistance training had no significant influence on CP, TE at CP or VO2 peak, the present study has also shown that six weeks of resistance training will not alter indices of endurance ability. The negative relationship between changes in the y-intercept and CP exposes a potential limitation of the linear CP function when evaluating changes in endurance ability following an intervention which significantly alters the y-intercept.

Adolescent↗
PubMed1995

The influence of recovery duration between periods of exercise on the critical power function.

It has been shown that when three periods of exercise at different intensities are performed to exhaustion, the linear regression of the work accomplished on the time taken defines the critical power (CP) function. The slope of this function is related to endurance ability, whereas the y-intercept is considered to represent anaerobic work capacity (AWC). The purpose of this study was to determine whether two different recovery durations (3 and 24 h), separating three periods of exercise, would elicit differences in the linear CP function. Nine healthy, untrained female students [19.5 (SD 1.6) years] completed five sessions of cycle exercise to exhaustion in random order (familiarisation). Three of these five power outputs were then used in the main part of the study in which the subjects were randomly assigned to two groups. Group one first performed the three power outputs on the same day, with 3 h of passive recovery separating each session (3 on 1). Group two first performed the three power outputs on 3 consecutive days, with approximately 24 h between sessions (3 con). Following 1 day of rest, group one repeated their three power outputs on 3 consecutive days and group two completed their three tests on the same day. Repeated-measures ANOVA revealed no significant differences between the mean values of CP or AWC calculated from the 3 on 1 or 3 con conditions. Trial two estimates of CP were, however, 3.4% (P < 0.05) higher than trial one (familiarisation) estimates. The results of this study showed that reliable measurements of both CP and AWC can be determined from three tests separated by rest periods of 3 h, provided that the subjects are first familiarised with the tests. We found one series of five exercise sessions to be sufficient familiarisation to ensure similar subsequent estimates of CP.

Adult↗
PubMed1994

The physiological and ventilatory responses to repeated 60 s sprints following sodium citrate ingestion.

This study examined the influence of sodium citrate on changes in selected blood, ventilatory and performance variables in response to intermittent sprint exercise. Eight moderately active male students completed three tests over a 6 day experimental period. The first test involved incremental exercise to determine VO2 max, while the second and third tests were identical in nature and involved five 60 s sprints cycling against 0.075 kg kg-1 body mass (BM); each of the five sprints was separated by 5 min passive seated recovery. Three days separated the VO2 max test and first interval test, while a further 3 days elapsed between the first and second interval tests. Ninety minutes prior to each interval test, the subjects consumed either a solution of sodium citrate (0.5 g kg-1 BM) or a placebo solution (1 g of calcium carbonate and 4 mg of sodium chloride). These were randomly administered in a double-blind crossover procedure so that every subject consumed each solution prior to the interval test over the 6 day period. Measures of work, VE, VO2, VCO2, post-exercise plasma lactate, and changes in both venous blood pH and venous blood bicarbonate (HCO3-) were measured during each interval test. Although analysis of variance failed to identify differences in performance between the two solutions, both exercise VCO2 and changes in venous blood HCO3- were higher in the citrate condition (P < 0.05). In addition, both peak post-exercise plasma lactate concentrations and post-exercise venous blood pH were significantly higher following citrate ingestion. Although these data are consistent with greater clearance of lactate and H+ from the active muscle cells following citrate ingestion, performance between the two trials was the same.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

The influence of dietary carbohydrate and pre-exercise glucose consumption on supramaximal intermittent exercise performance.

The present study examined whether a pre-exercise consumption of glucose by subjects having adhered to a 3-day low carbohydrate (CHO) or normal CHO diet would influence supramaximal intermittent exercise performance. Sixteen moderately active men volunteers (mean(s.d.) age 20.0(1.3) years) agreed to undertake three exercise tests over an 8-day period; in addition to completing a VO2max test, the subjects performed two identical maximal interval tests (MIT1 and MIT2). Periods of 3 days separated each of the three tests. The interval tests involved five 60-s 'all-out' cycling bouts working against a resistance of 0.075 kg kg-1 body mass; each bout was separated by 5 min of passive recovery. For 3 days preceding the first interval test (MIT1), all subjects adhered to a 'moderate' CHO diet which comprised 59.1% (approximately 4.1 g kg-1 body mass) of the daily energy intake as CHO. Following MIT1 and for 3 days before MIT2 subjects were randomly assigned to follow either a moderate CHO diet (60.8%) or a low CHO diet (14.4% or 1.1 g kg-1 body mass). All food and drink consumed during the experimental period was weighed and recorded for later dietary analysis. One hour before MIT2, eight subjects were administered (in single blind fashion) a 15% glucose solution (1 g kg-1 body mass) while the other eight subjects consumed a low-energy sweetened placebo. During both interval tests, values of work, exercise VO2, plasma glucose, plasma lactate and venous blood pH were statistically analysed. No changes in performance between MIT1 and MIT2 across conditions were found (P > 0.05). However, those subjects who consumed the glucose solution before MIT2 (irrespective of their dietary CHO intake) consumed significantly less oxygen during exercise than those who had been given the placebo solution (P<0.05). While these findings question the ergogenic potential of consuming glucose before supramaximal exercise, the VO(2) data implicate a possible shift in substrate utilization during repeated sprint exercise after pre-exercise glucose ingestion.

Adult↗
PubMed1993

The influence of dietary carbohydrate on performance of supramaximal intermittent exercise.

The present investigation examined the influence of dietary carbohydrate (CHO) on the performance of supramaximal intermittent exercise. A group of 14 moderately trained male students [mean age 21.0 (SD 1.6) years] completed a maximal oxygen consumption test and two identical 'maximal interval tests' (MIT1 and MIT2) over a 10-day experimental period. Each MIT involved five 60-s all-out periods of cycling (against 0.736 N.kg-1 body mass), with each period separated by 5 min of passive recovery. All subjects consumed a moderate CHO diet for 3 days preceding MIT1 (55.3% of energy intake as CHO) and were then randomly assigned to either a high CHO (83%), moderate CHO (58%) or low CHO (12%) diet for the 3 days separating MIT1 and MIT2. All food and drink consumed during the experimental period was weighed and recorded for later dietary analysis. Measurements of work done, exercise oxygen consumption (VO2), venous blood pH, plasma lactate and plasma glucose concentrations were compared between interval tests. Independent Student's t-tests revealed that the 5.6% increase in total work done recorded by the high CHO group and the 2.3% increase by the moderate CHO group between MIT1 and MIT2, were significantly different to the 5.4% decrease in performance recorded for the low CHO group (P < 0.001 and P < 0.01, respectively). No significant differences in performance changes was found between the high and moderate CHO groups; 10 subjects in each of these groups would have been necessary to attain significance at the 0.05 level using the same procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Decreased salivary immunoglobulins after intense interval exercise before and after training.

Endurance athletes have been shown to suffer a high incidence of upper respiratory tract infection (URTI). Previous studies have shown that concentration and flow rate of secretory immunoglobulin A (IgA), the major effector of host resistance to URTI, decrease after intense endurance exercise. The purpose of this study was to determine whether salivary IgA concentration and flow rate decrease after brief intense interval exercise, and whether the response to exercise changes with training. Twelve male subjects performed five 60-s bouts of supramaximal interval exercise at 0.075 g.kg-1 body mass on a cycle ergometer; each bout was separated by 5-min rest. Subjects then trained for 8 wk by performing the same interval exercise protocol three times per week. Timed, whole unstimulated saliva samples were obtained before and after the interval exercise protocol, before and after training. Salivary IgA, IgG, and IgM concentrations were measured by ELISA and flow rates calculated. IgA and IgM concentrations relative to total protein decreased after each exercise session; IgG concentration relative to total protein did not change after exercise. IgA, IgM, and IgG flow rates decreased 50-65% after interval exercise. There was no effect of training on any immune parameter measured, although total work performed in the five 60-s bouts increased after training. These data show that the output of salivary IgA and IgM decrease after brief supramaximal interval exercise, and that the decreased output is due, at least partially, to the decrease in saliva flow. In addition, there appears to be a specific effect of intense exercise on IgA concentration greater than that due to decreased saliva flow alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The influence of high-intensity exercise training on the Wlim-Tlim relationship.

When exercise to exhaustion is performed using at least two different intensities, work to fatigue (Wlim) can be expressed as a linear function of time to fatigue (Tlim). Whereas the slope of this function is related to endurance ability, the y-intercept is associated with the potential to perform high intensity interval exercise. The purpose of the present investigation was to determine the influence of 8-wk intermittent high-intensity exercise training on the y-intercept derived from the Wlim-Tlim relationship. Eight healthy, untrained male students (19.1 +/- 0.6 yr) completed five 60-s bouts of maximal exercise on the cycle ergometer, three times a week, for 8 wk. Seven controls avoided regular activity for the same period. Prior to and immediately following the training period, the Wlim-Tlim relationship, VO2max, and total work completed in five 60-s exercise bouts on the cycle ergometer were determined. Correlational analysis established relationships between the y-intercept and total work accomplished in the interval test pre- (r = 0.90; P < 0.01; N = 15) and post-training (r = 0.92; P < 0.01; N = 15), confirming that the y-intercept is related to the ability to perform exercise of this nature. Moreover, the "anaerobic" energy yield, calculated from total work and oxygen consumed during the interval exercise, was also related to the y-intercept (r = 0.78; P < 0.01). Interval training significantly increased both the y-intercept (P = 0.0015) and total work accomplished in the interval test (P = 0.001), while the slope of the Wlim-Tlim relationship (critical power) remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1992

Endurance training enhances critical power.

The present investigation was conducted to determine whether critical power (CP) assesses the ability to perform continuous aerobic exercise and to determine whether training-induced changes in aerobic endurance are reflected by changes in the slope, but not the y-intercept of the CP function. Twelve healthy, active, but untrained male students (mean age +/- SD = 19.1 +/- 0.8 yr) undertook 8 wk of cycle ergometer endurance training (30-40 min a day, three times a week) at an intensity corresponding to their CP. Six control subjects of similar age and initial training status refrained from regular exercise for the same period. Before and immediately following the training period, each of the 18 participants completed three cycle ergometer tests to determine their CP function, an incremental exercise task to establish their maximal oxygen uptake (VO2max), and 40 min of continuous cycle ergometry at or near their calculated CP. CP was significantly correlated with endurance time at 270 W (r = 0.65, P < 0.05) and with the mean power that could be maintained for 40 min (r = 0.87-0.95, P < 0.01), but overestimated the latter by less than 6%. In response to endurance training, CP increased from a mean of 196 +/- 40.9 W to 255 +/- 28.4 W (31%) (ANCOVA, P < 0.01), while the mean power output maintained for 40 min of exercise increased from 190 +/- 34.5 W to 242 +/- 34.9 W (28%). VO2max increased from 49.2 +/- 7.8 ml.kg-1.min-1 to 53.4 +/- 6.4 ml.kg-1.min-1 (8.5%) (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗