Significant Increase In VO2max Research Articles

Continuous assistive-passive exercise and cycle ergometer training in sedentary women

Continuous assistive-passive exercise (CAPE) is a new exercise modality that has become popular with older females. To evaluate the efficacy of CAPE, 43 sedentary, postmenopausal women (PMW) were randomly divided into three groups: CAPE training (N = 15), cycle ergometer training (N = 14), and control (N = 14). The CAPE training consisted of 10 min bouts on six CAPE tables, twice per week. The cycle ergometer group trained twice per week for 30 min per session, at 70-85% of maximal heart rate. The cycle ergometer and CAPE groups trained for 12 wk, while the control group remained sedentary for the duration of the study. Groups were similar with respect to age, height, weight, girths, skinfolds, and aerobic power (VO2max) upon entering the study (P greater than 0.05). The groups were tested pre- and post-training on the sum of seven body girths (sigma 7G), sum of four skinfolds (sigma 4SF), weight, and VO2max. A 3 d dietary recall was recorded pre and post and analyzed for total caloric intake. Following training, changes in caloric intake, sigma 7G, and sigma 4SF were not significantly different among groups. The cycle group lost 1.1 kg (P less than 0.05) and increased VO2max (l.min-1) by 9.2% (P less than 0.05), while the CAPE group significantly decreased VO2max (P = 0.04). Our results indicate that CAPE does not alter sigma 7G or sigma 4SF in sedentary PMW and that two 30 min sessions of cycle training per week at 70-85% of maximal heart rate can result in moderate but significant increases in VO2max in sedentary PMW.

Dynamics of changes in the cardiovascular response to submaximal exercise during low-intensity endurance training with particular reference to the systolic time intervals.

Eighteen male volunteers (aged 20-23 years), not involved in any sporting activities, were submitted to 13 weeks of training consisting of 30 min exercise [at 50%-75% maximal oxygen intake (VO2max)] on a cycle ergometer, performed 3 times a week. Every 4 weeks cardiac function was evaluated by measuring the systolic time intervals at rest and during submaximal cycle exercise. Stroke volume (SV), heart rate (HR) and blood pressure (BP) responses to submaximal exercise, VO2max and anaerobic threshold (AT) were also determined. Significant increases in VO2max, increases in AT and SV at the submaximal exercise intensities, as well as decreases in HR and BP were found after 4 weeks of training. Resting systolic time intervals were not affected by training, but during the submaximal cycle exercise the values of the pre-ejection period (PEP) and isovolumic contraction time (ICT) corresponding to HR of 100 beats.min-1 were significantly lowered after 13 weeks of training, whereas PEP, ICT and total electromechanical systole corresponding to HR of 130 beats.min-1 were significantly shortened by the 4th week. The ratios of PEP:LVET (left ventricular ejection time) and ICT:LVET during submaximal exercise were significantly lowered by training starting from the 8th week. These changes might be interpreted as evidence of the training-induced enhancement of the "contractility reserve", i.e. the ability to increase heart muscle contractility with increasing exercise intensity.

Longitudinal assessment of responses by triathletes to swimming, cycling, and running

Fourteen triathletes (eight male, six female) were tested four times (in February, May, August, and October) to monitor adaptations to training for a triathlon (1.9-km swim, 90.3-km bike, 21.1-km run). VO2max was measured during treadmill running (TR), cycle ergometry (CE), and tethered swimming (TS). Lactate threshold (LT), defined as the VO2 at a lactate concentration of 4 mM, was determined during TR and CE. In all sessions, TS VO2max was less than TR and CE (P less than 0.05), and CE was less than TR (P less than 0.05). Means for Session I were 57.4, 53.4, and 48.3 ml.min-1.kg-1 for TR, CE, and TS, respectively. Corresponding values for Session IV were 58.4, 56.0, and 47.8 ml.min-1.kg-1. The only significant increase in VO2max was for CE (5%). VO2 at the LT increased from Session I to IV for both TR (6%) and CE (10%); the LT for TR was at a higher VO2 than for CE in all sessions. The percent VO2max at LT for TR in Sessions I and IV was 80 and 85%, respectively. Analogous values for CE were 72 and 76%. The minimal increases in VO2max suggest that subjects had reached their potential in this parameter. Improvements in race performance were probably attained through peripheral adaptations, as suggested by increases in the VO2 at LT. The occurrence of the LT at a lower percent VO2max in cycling than in running suggests that the triathletes had greater potential for improvement in cycling.

Effect of 6 d of exercise training on responses to maximal and sub-maximal exercise in middle-aged men.

Nine sedentary men (53 +/- 3 yr) were studied before and after 6 d of endurance exercise training to determine the effects on maximal oxygen uptake (VO2max), and on the heart rate, blood pressure, and metabolic responses to a standard bout of steady-state sub-maximal exercise. The subjects exercised approximately 1 h.d-1 at about 68% of VO2max. The 6-d protocol elicited no improvement in VO2max (2.50 +/- 0.14 before vs 2.58 +/- 0.15 l.min-1 after training). Heart rates were significantly lower by 5 to 8 b.min-1, systolic blood pressures were reduced by 16 to 19 mm Hg, and blood lactate concentrations were 25 to 35% less at the same exercise intensities (60, 70, and 80% of VO2max) after 6 d of exercise. Rate pressure product was about 15% lower at the same exercise intensity after 6 d of training (P less than 0.05). The respiratory exchange ratio during submaximal exercise was 0.02 to 0.04 units lower (P less than 0.05; P less than 0.01) after 6 d of exercise, indicating a shift in substrate utilization favoring fat oxidation. These findings suggest that short-term endurance training can induce heart rate, blood pressure, and metabolic adaptations to sub-maximal exercise before there is a significant increase in VO2max in sedentary, middle-aged men who are capable of vigorous exercise.

Interaction of test protocol and horizontal run training on maximal oxygen uptake

Twenty-seven untrained college-age males (mean age = 23.1 yr) volunteered for this 12-wk training study, which investigated potential interactions between training specificity and treadmill protocol specificity. The study was designed to analyze the interaction between a subject's maximal oxygen uptake (VO2max) on an inclined protocol (IP) vs a horizontal protocol (HP) before and after training exclusively on flat terrain. Experimental subjects (E, N = 17) trained by running on flat terrain for 12 wk, 4 d/wk, 37 min/d at an intensity equal to 65 to 85% of their heart rate reserve while control subjects (C, N = 10) remained sedentary. All subjects underwent a minimum of four maximal treadmill tests (two with an IP and two with a HP) prior to training and two maximal treadmill tests (one IP and one HP) post-training. Multivariate analysis of variance and post-hoc t-tests using a pooled variance-covariance matrix were used to analyze the data. Alterations in E, consequent to training, included significant increases in VO2max [mean IP = 53.6 to 58.4 (+8.9%) and mean HP = 51.7 to 56.2 ml. kg-1 . min-1 (+8.7%)]. C showed a significant pre- to post-training decrease on the HP for VO2max [mean HP = 52.4 to 50.7 ml . kg-1 . min-1 (-3.2%)], but showed no significant change on the IP. There was no significant pre- to post-training interaction between protocols for VO2max. It was concluded that the post-training results do not support the concept of protocol specificity when evaluating VO2max in subjects trained exclusively on flat terrain.

The effect of training on exercise-induced R-wave amplitude changes in young females

The effects of an exercise training program on R-wave amplitude (Ramp) changes during graded exercise were investigated in 14 adolescent females. The experimental group (EG) (N = 6) underwent a 20-wk aerobic exercise program. Eight subjects served as controls (CG). Oxygen uptake (VO2), heart rate (HR), and Ramp were determined during incremental exercise to exhaustion, pre- and post-program. The Ramp was calculated by using the average of 10 electrocardiographic complexes to provide a stable criterion. Pre-training, EG and CG were not significantly different for VO2max and HRmax; Ramp decreased significantly between rest and 5 min prior to exhaustion for both groups (P less than 0.05). Ramp changes were significant between the first min of exercise and 2 min prior to exhaustion for EG (P less than 0.05) and between the first min of exercise and 1 min prior to exhaustion for CG (P less than 0.05). These changes occurred at 87% of VO2max and 95% of HRmax for EG and at 93% of VO2max and 97% of HRmax for CG. CG showed no change in these variables post-program except for Ramp exhibiting a significant change between rest and the first min of exercise (P less than 0.05). EG showed a significant increase in VO2max (P less than 0.05), and Ramp changes during exercise were delayed. The first significant change occurred between rest and 3 min prior to exhaustion (P less than 0.05), and the second change occurred between the first min of exercise and exhaustion (P less than 0.05). Thus the latter Ramp change was delayed to 100% of VO2max and HRmax post-training.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic exercise training in foxhounds. I. Oxygen consumption and hemodynamic responses.

Ten foxhounds were studied during maximal and submaximal exercise on a motor-driven treadmill before and after 8-12 wk of training. Training consisted of working at 80% of maximal heart rate 1 h/day, 5 days/wk. Maximal O2 consumption (VO2max) increased 28% from 113.7 +/- 5.5 to 146.1 +/- 5.4 ml O2 X min-1 X kg-1, pre- to posttraining. This increase in VO2max was due primarily to a 27% increase in maximal cardiac output, since maximal arteriovenous O2 difference increased only 4% above pretraining values. Mean arterial pressure during maximal exercise did not change from pre- to posttraining, with the result that calculated systemic vascular resistance (SVR) decreased 20%. There were no training-induced changes in O2 consumption, cardiac output, arteriovenous O2 difference, mean arterial pressure, or SVR at any level of submaximal exercise. However, if post- and pretraining values are compared, heart rate was lower and stroke volume was greater at any level of submaximal exercise. Venous lactate concentrations during a given level of submaximal exercise were significantly lower during posttraining compared with pretraining, but venous lactate concentrations during maximal exercise did not change as a result of exercise training. These results indicate that a program of endurance training will produce a significant increase in VO2max in the foxhound. This increase in VO2max is similar to that reported previously for humans and rats but is derived primarily from central (stroke volume) changes rather than a combination of central and peripheral (O2 extraction) changes.

Skeletal muscle adaptation in adolescent boys: sprint and endurance training and detraining.

The purpose of the present study was to investigate the effects of 3-month sprint and endurance training programs on the vastus lateralis muscle fiber area and the activities of glycolytic (phosphofructokinase; PFK) and oxidative (succinate dehydrogenase; SDH) enzymes of adolescent boys. Enzyme activities were also determined after a subsequent 6-month detraining period. Endurance training resulted in significant increases in VO2max (58.4 to 64.3 ml . min-1 . kg-1), in ST and FTa fiber area (6.0 to 7.3 and 8.0 to 10.4 microns 2 x 10(3), respectively), and in SDH activity (6.4 to 9.1 IU). After detraining VO2max and SDH activity returned to pretraining levels. Sprint training resulted in a significant increase only in PFK activity (28.1 to 33.9 IU), which was also abolished in the detraining period. These data demonstrate that in adolescent boys skeletal muscle enzyme changes are specific to the mode of training and that they are similar in direction but different in magnitude to those found in adults.

Physiological and muscle enzyme adaptations to two different intensities of swim training.

To test the hypothesis that a smaller quantity of high intensity (HI) as opposed to a larger quantity of moderate intensity (MI) swim training would result in adaptations more specific to the short performance times of swimming competitions, two groups of elite university swimmers were tested before and after 6.5 weeks of specific HI or MI intermittent swim training. In training, swimming times were faster and blood lactate concentrations were higher (10.2 vs. 7.5 mM) during HI compared to MI training. No significant differences were observed between the two groups for any of the variables measured, before or after training. However, significant increases with training were observed for the activities of hexokinase, phosphorylase, phosphofructokinase, succinate dehydrogenase, and 3-hydroxyacyl CoA dehydrogenase in the deltoid, but not the gastrocnemius muscles. Training resulted in significant increases in VO2 max during treadmill running, but not during tethered swimming. It is concluded that a larger quantity of MI swim training results in physiological adaptations that are similar to those obtained with a smaller quantity of HI training, at least over a relatively short training period.

Increase in sweating sensitivity by endurance conditioning in man.

Sweating sensitivity has been evaluated at rest in 10 competitive athletes (cross-country skiers and swimmers). Three sedentary men underwent a 3-mo period of endurance training in a temperate climate, (dry bulb temperature (Tdb): 18 degrees C) and had their sweating sensitivity measured before and after the training period. Mean maximum oxygen uptake (Vo2max, ml.min(-1).kg(-1)) was: skiers: 66.5; swimmers 65.8; sedentary men, pretraining 40.9; posttraining: 48.3 (+18%). Sweat output of athletes under a given stress (passive heating) was markedly higher than that of sedentary men. Skiers exhibited a high level of heat tolerance and were better acclimatized than swimmers, although they had never experienced exposure to heat. The increase in Vo2max of sedentary men was accompanied by 1) an increase in sweating sensitivity with a decrease of body heat storage at steady state (pretraining: 5.4 kJ.kg(-1); posttraining: 3.5 kJ.kg(-1); P less than 0.05); 2) significant shift down the temperature scale with reduced rectal temperature (Tre) for sweat onset; 3) an increase of gain constants of sweating (W.m-2 degrees C(-1) (pretraining: 168; posttraining: 269; gain constant of swimmers: 222). It was suggested that endurance training in cold or temperate conditions with significant increase of Vo2max could act on the thermoregulatory function in a way similar to body heating procedures, such as work in heat, and could contribute to heat acclimatization.

Cardiorespiratory responses of sedentary college women as a function of training intensity

Twenty-seven sedentary college women trained on a treadmill 3 times weekly over a 9-wk experimental period. Subjects exercised at a heart rate (HR) of either 50 or 65% of the HR reserve added to the resting HR with the duration of each session limited to the time required to elicit 1,000 beats above the resting value. Treadmill speed was adjusted automatically to maintain the prescribed exercise heart rate (EHR) within +/- 5 beats-min(-1). A comparison of the pretraining and posttraining results revealed that both training intensities caused significant increases in VO2max (1-min(-1) and ml-kg(-1)-min(-1)), V at VO2max, and O2 pulse at VO2max, and a significant decrease in VEO2 at VO2max. There was no alteration in EHR at VO2max for either intensity. For every dependent variable in which training effects were noted, the absolute gain made by the subjects training at the 65% intensity was greater than for those exercising at 50%. In no instance, however, was the difference between groups statistically significant. It was concluded that training at an EHR of either 50 or 65% of the HR reserve plus resting HR is sufficient to elicit a training response.