Effect of different sprint training regimes on the oxygen delivery-extraction in elite sprinters.

AIM: The effects of sprint training regimes of varying distance schedules on the oxygen delivery-extraction relationship were investigated in 15 young (22+/-1 years) healthy males national-level sprinters. METHODS: During one session subjects performed four sprints, in a schedule of increasing distance order (100, 200, 300 and 400 m), and during the other session, in a schedule of decreasing distance order (400, 300, 200, and 100 m). All sprint bouts were performed on a treadmill at a speed of 22 km/h-1, which corresponds to 85% of subjects' maximal speeds. The order of the running sequences during sessions was balanced over subjects. RESULTS: During both sprint schedules, all variables except for oxygen extraction in the incremented training regime, increased significantly from rest to exercise. Training regimes were not different with regard to cardiac output and absolute oxygen uptake. However, the decreasing compared to the increasing scheme was characterized by significantly (P<0.05) higher mean values of heart rate (194.5+/-4.1 185.2+/-5.7 beats/min-1, respectively), oxygen extraction (54.3+/-3.8 and 47.1+/-3.4 mL/L-1, respectively) and lactate (10.6+/-0.5 and 9.2+/-0.7 mmol/L-1, respectively), while stroke volume was significantly (P<0.05) lower (100.4+/-4.5 and 109.7+/-4.4 mL, respectively). CONCLUSION: The present study indicates that in sprinters performing a similar distance at the same speed, but under different training regimes interplay exists between oxygen delivery and extraction, suggesting a link between the type of training scheme and physiological cardiovascular and skeletal muscle metabolic adaptations. This may explain the absence of differences between the conditions in absolute oxygen uptake and peak power output.

Effects of different sprint cycling bouts on left ventricular function in top cyclists.

AIM: The study investigated lactic acid and left ventricular function in response to two different sprint cycling schedules varying in their time schedule, in 15 healthy national level cyclists (23+/-1 years). METHODS: During one testing session subjects performed four strenuous bouts in a schedule of increasing time order: 1, 2, 3 and 4 min. In the other session, they performed a decreasing order: 4, 3, 2 and 1 min. Resting time between bouts in the increasing schedule were 2, 3, and 4 min, respectively. Resting times for the decreasing schedules were 4, 3 and 2 min, respectively. Exercise bouts were performed on an electrical cycle ergometer at 85% of each subject's maximal speed velocity. RESULTS: In both sprint cycling schemes, mean end-systolic volume and mean end-diastolic volume decreased significantly (P < 0.05) with bout's time. However, there was a significant interaction effect regarding schedule order and lactate accumulation. In the incremented scheme, lactate accumulated gradually during the session, while a high level of lactate was maintained throughout the decremented scheme (from 3.8+/-0.7 to 11.8+/-1.8 and from 9.5+/-1.5 to 10.8+/-1.9 mmol.L-1, respectively). Furthermore, analysis of cardiac function during the two schemes demonstrates different physiological responses. The decreasing scheme was characterized by a higher mean heart rate, a lower mean stroke volume and a lower mean end-diastolic volume (P < 0.05) indicating that during the two schemes, the functional mechanisms underlying cardiac response, are different. CONCLUSION: Our data suggest that in the face of high levels of lactic acid, during the decreasing scheme, venous return may be impeded, most likely due to reduced left ventricular filling time and inadequate vasodilatation of the arteries during the early phase of cycling bout. In addition, it suggests that the decreasing scheme may yield a better anaerobic and cardiovascular training method.

Weight lifting training and left ventricular function in adolescent subjects.

AIM: Training during adolescence may influence the myocardium's adaptation. Effects of exercise training on left ventricular function differ depending whether they result from pressure or volume overload. Accordingly, the present study was designed to examine, by echocardiography studies, the effects of endurance versus weight lifting training modes on left ventricular contractility in healthy adolescent boys. METHODS: Sixty healthy adolescent boys were randomly and evenly divided into 3 groups: weightlifting training, run-training, and control. Exercising groups underwent 28-week training programs, 3-4 times a week, 35 min each session. The weight lifting program for consisted of training on 6 dynamic resistive machines at resistance corresponding to 6-repetition maximum. The running program was composed of aerobic exercise training at 65% of their VO(2max). RESULTS: At rest, only in the runners end diastolic volume and end systolic pressure-volume ratio differed significantly (P<0.05) from pre- to post-testing. During post-testing session at peak exercise, runners compared to weightlifters demonstrated improvement respectively in: wall stress (245+/-42 and 290+/-35 103 dyn.cm(2)), end systolic pressure-volume ratio (7.2+/-.7 and 6.4+/-.5 ratio) and ejection fraction (82+/-5% and 76+/-5%). Maximal oxygen uptake (48.2+/-3.2 and 43.8+/-3.5 mL.kg(-1).min(-1)), also improved significantly (P<0.05). Maximal load was significantly (P<0.05) higher in the runners and weight lifters than in the control group with significantly (P<0.05) higher values for the weight lifters than runners. CONCLUSION: This study has showed that in adolescent boys the mode of exercise training leads to significant differences in left ventricular function and contractility, related to differences in volume-after-load relationship and not to fundamental differences in the properties of the myocardium.

Effects of gradient and load carried on human haemodynamic responses during treadmill walking.

This study examined the effects of different loads carried and gradients, on haemodynamic and cardiovascular responses during 45 min of treadmill walking. A group of 20 male endurance-trained athletes [mean maximal oxygen uptake 61.4 (SD 4) ml x kg(-1) x min(-1)] volunteered for this study. The subjects took part in three separate trials. The first involved a backpack weighing 25 kg, the second a 35 kg backpack, and the third trial, unladen, while walking on a treadmill at a speed of 5 km x h(-1). The subjects began walking on the treadmill with the randomized load at 0% gradient. After 15 min, the gradient was increased by 5% every 15 min for a total of 45 min. The order of the loads carried was randomized among subjects. No significant differences were noted for all the variables measured attributable to loads between 25 kg and 35 kg. However, significant (P<0.05) differences were seen for all variables each time the gradient was increased. Cardiac output increased from 11.4 (SD 0.6) 1 x min(-1) at 0% to 13.6 (SD 0.8) l x min(-1) at 5% and to 17.6 (SD 1.3) l x min(-1) at 10% carrying the 35 kg load. Similarly, lactic acid concentrations in the blood increased from 2.8 (SD 0.2) to 3.1 (SD 0.6) and to 5.3 (SD 1.3) mmol x l(-1), respectively. Similar changes were observed for all variables while carrying the 25 kg load. In addition, steady states in oxygen uptake and other physiological variables were obtained throughout the course of the tests. These data suggest that during isodynamic exercise, one of the main factors determining metabolic and haemodynamic responses will be the change in gradient and to a lesser extent, the mass of the load carried.

Left ventricular contractility and function at peak aerobic and anaerobic exercises.

PURPOSE: The present study compared and evaluated left ventricular function and contractility at peak incremental aerobic type exercise and all-out explosive anaerobic effort in young healthy trained subjects. METHODS: Twenty-two young healthy trained subjects (19 +/- 1 yr) were studied by two-dimensional direct M-mode echocardiography at peak aerobic and at peak all-out anaerobic exercises, performed on cycle ergometer. RESULTS: All subjects completed the study without any electrocardiographic abnormalities. Significant (P < 0.05) differences between the aerobic and the anaerobic efforts were noted for peak cardiac output (24 +/- 2.0 and 15.0 +/- 1.1 L x min (-1), respectively), left ventricular pressure-volume ratio (5.8 +/- 0.6 and 4.7 +/- 0.5 respectively), end systolic volume (33 +/- 4 and 42 +/- 5 mL, respectively), ejection fraction (79 +/- 7 and 66 +/- 5%, respectively), and total peripheral resistance (TPR) (367 +/- 90 and 704 +/- 90 dynes x s(-1) x cm(- 5), respectively). CONCLUSIONS: These data suggest that left ventricular at peak all out anaerobic effort differed markedly from those observed at peak aerobic exercise. These differences are presumably due to the different after-load responses between the two exercise modes. Therefore, it is suggested that anaerobic-type effort should be performed with great caution in normal young healthy subjects.

Reliability of isokinetic strength measurements of the knee in children with cerebral palsy.

This study evaluates the reliability of isokinetic testing of the knee flexors and extensors in children with cerebral palsy (CP). Twelve children (seven girls, five boys), aged 9 to 15 years, participated in this study. The children's strength was measured bilaterally, using a dynamometer. Each participant was tested twice at an interval of 1 week. During each session, the participant performed five consecutive cycles of knee extension and flexion. Testing velocity was set at 90 degrees/s, and the range of motion was 80 degrees, starting with the knee flexed at 80 degrees and ending in full extension. The measured variable was the peak torque. Reliabilities were determined using intraclass coefficient (ICC) with two-way ANOVA model. The ICCs for individual sessions range from 0.90 to 0.99. ICCs for the eight repetitions over the two sessions range from 0.95 to 0.98. The findings indicate that measuring isokinetic strength in the tested population is highly reliable and should be considered in rehabilitation protocols.

Isokinetic strength and endurance of the knee extensors and flexors in trans-tibial amputees.

Significant levels of muscular fatigue alter the co-ordination patterns and the ability to accomplish proper daily functions, especially in patients with initial low levels of strength. The purpose of this study was to evaluate the strength and endurance of the quadriceps and hamstring muscles in trans-tibial amputees. Concentric strength and endurance of the thigh muscles were measured bilaterally by an isokinetic dynamometer. The measured variables were torque and angle. For the endurance test, a fatigue index was calculated. Peak torque for extension and flexion was significantly higher in the sound limb (p<0.01). The fatigue index for extension was not significantly different in the sound limb from the amputated limb. The fatigue index for flexion is significantly higher in the sound limb (p<0.01). The finding may imply that from a metabolic point of view, the muscles of the amputated limb function properly. It is of great importance to reduce the bilateral deficit and the degree of atrophy as soon as possible in order to improve the level of performance. By choosing a correct strength and endurance training programme, one may expect to get a significant and good reaction from the muscles of the amputated limb as is expected from training the muscles of a sound limb.

Direct vs. indirect blood pressure measurement at peak anaerobic exercise.

The present study compared the direct intra-arterial method with the indirect conventional sphygmomanometer during all-out anaerobic exercise, in young healthy subjects. Systolic and diastolic blood pressures were measured by intraarterial means and by auscultation. Fourteen young healthy males (23+/-2 yrs) were measured at rest and during all-out anaerobic exercise. Comparisons were made with simultaneously determined intra-arterial catheter and auscultation measurements. The data suggest that indirect systolic pressure is highly correlated with the direct method at rest (r = 0.684), with mean of 107+/-7 and 101+/-6 mmHg, respectively, and during all-out anaerobic exercise (r = 0.87), with mean of 197+/-11 and 191+/-9 mmHg, respectively. Indirect diastolic blood pressure correlates well with intra-arterial at rest (r = 0.62), with mean of 84+/-11 and 77+/-9 mmHg, respectively. However, during all-out anaerobic exercise, the correlation coefficient between the direct and the indirect methods was low (r = 0.36), with mean of 101+/-12 and 103+/-9 mmHg, respectively. These results suggest that when utilizing an all-out anaerobic exercise, the indirect method is not valid for assessment of diastolic pressure. In addition, although the anaerobic test is a dynamic type of exercise, its blood pressure responses for both direct and indirect methods were similar to those seen during isometric exercise.

Perceptual responses to exercise: the effect of load-awareness on physiological responses during an isometric bout.

To evaluate the effect of awareness of load on cardiovascular and metabolic responses, thirty males were compared in three different loads during upright deadlift isometric exercise, at 25%, 30% and 35% of maximal voluntary contraction for 3 min. Significant differences (P < 0.05) were found from rest to 25%, 30% and 35% for all physiological variables, heart rate (66.5+/-9.0, 104.0+/-12.0, 115.0+/-9.0, and 123.0+/-11.0 beats x min(-1), respectively), and for lactic acid (2.2+/-0.4, 4.6+/-0.7, 5.7+/-1.1, and 6.3+/-1.5 mM x l(-1), respectively). However, no significant differences were revealed between the various conditions when rate-perceived exertion data were analyzed, despite increased absolute loads. These data indicate that the psychological manipulation introduced in this study did not affect physiological responses during isometric exercise, in contrast to that seen during dynamic exercise.

The effect of gender on left ventricular function immediately after the wingate test.

The effect of gender on left ventricular systolic function and exercise haemodynamics in healthy young subjects was studied during 30-s all-out sudden strenuous dynamic exercise. A group of 22 men [19.3 (SD 1) years] 20 women [19.1 (SD 1) years] volunteered to participate in this study. Two-dimensional direct M-mode and Doppler echocardiograph studies were performed with the subject in the sitting position. The Doppler examination of flow was located with continuous-wave, interrogating ascending aorta measurements. The subjects completed the study without showing any electrocardiograph abnormalities. An interaction effect with stroke volume (P < 0.05) was characterized by a decrease in the men and an increase of stroke volume in the women. Cardiac output rose significantly (P < 0.05) up to 14.5 (SD 6) 1.min-1) for the men and 12.1 (SD 4) 1.min-1 for the women compared to the rest values [5.8 (SD 0.4) and 4.7 (SD 0.5) 1.min-1, respectively]. Flow velocity integral and acceleration time differed significantly between the two groups at rest (P < 0.05). During exercise these differences showed an interaction effect (P < 0.05). These results would indicate that normal men and women respond to sudden strenuous exercise by reducing their left ventricular systolic function, with a significantly greater decrease in women (P < 0.05). The gender differences in the haemodynamic responses during the present study, may, as suggested by others, be attributable to differences in energy metabolism. In addition, changes in Doppler parameters of aortic flow, haemodynamics and blood pressure responses during sudden strenuous exercise differed markedly from those seen before with endurance exercise.

Effects of chronic overload training and aging on left ventricular systolic function.

To examine the effects of age and chronic overload training on left ventricular systolic function during static exercise, Doppler echocardiography studies were performed in 14 young (28 +/- 6 years) and 10 older (51 +/- 3 years) weight lifters and also in 14 young (29 +/- 6 years) and 10 older (52 +/- 1.1 years) normal individuals during upright dead-lift isometric exercise, at 30% of maximal voluntary contraction for 3 min. At rest, older weight lifters demonstrated impaired left ventricular systolic function as compared with the other three groups. During exercise, peak and mean velocity values increased significantly (p < 0.05) from resting values in the young groups, but remained unchanged in the older groups. Flow period and acceleration and deceleration times were significantly (p < 0.05) lower in the younger subjects than those observed for the old ones, with the highest (p < 0.05) values obtained by the old weight lifters. This study suggests that the differences between the groups are related to differences in impedance and not to fundamental changes in the properties of the myocardium.

Direct vs indirect blood pressure at rest and during isometric exercise in normal subjects.

Systolic and diastolic blood pressures were measured by intraarterial means and by auscultation. Comparisons were made with simultaneously determined intraarterial catheter and auscultation measurements. Five healthy males were measured at rest and during handgrip and deadlift isometric exercises, utilizing small and large muscle mass. The data suggest that indirect systolic blood pressure is highly correlated with the direct method at rest, during handgrip and deadlift (0.8, 0.9 and 0.91 respectively) isometric exercises. Indirect diastolic blood pressure correlates well with intraarterial at rest (0.7) and during the isometric handgrip bout which utilized small muscle mass (0.8). As for the deadlift manoeuvre, the correlation coefficients between the indirect and direct methods were low. These results suggest that when utilizing large muscle mass during isometric deadlift exercise, the indirect method is not valid for assessment of diastolic blood pressure.

Physiological characteristics of female 100 metre sprinters of different performance levels.

The purpose of this study was to compare physiological characteristics of three different levels of 100 m female sprinters. The 30 subjects in this study (20 female track athletes and 10 recreationally trained females) were assigned, according to their 100 m running time, to one of three different groups: "Fast" (11.8 +/- 0.1 sec), "Average" (12.7 +/- 0.1) and "Slow" (14.2 +/- 0.1 sec). All subjects were tested for performance in the Wingate Anaerobic Test (WAnT), strength (squat exercise), fat % (hydrostatic weighing), reaction time, flexibility (sit-and-reach test), aerobic power (peak VO2) and running skill. The data was analyzed by one-way Analysis of Variance (ANOVA) with post-hoc Tukey test, which was performed on each variable to find differences between the groups. The ANOVA indicated significant differences among all three groups for performance in the Wingate Anaerobic Test and relative strength. Significant differences in fat % and running skill were found between the fast and the slow groups and between the average and the slow groups. However, no significant difference in fat % and running skill existed between the fast and the average groups. The differences in reaction time were significant only between the fast and the average groups. No two groups were significantly different from each other for flexibility and peak VO2. Pearson correlation coefficients (r) were calculated to determine the relationships between the 100m running time and each of the variables tested. Significant and negative correlations were found between the 100m running time and skill, relative strength, and performance in the WAnT. Significant and positive correlations were found between running time and fat %. No significant correlations were found between running time and peak VO2 reaction time and flexibility. Stepwise regression analysis indicated that the combination of performance in the WAnT and strength provided the most efficient (R = 0.92) prediction of 100 m run times. This study demonstrated that the main difference among female sprinters of different performance levels lies in their ability to produce muscular power, strength and running technique. Other physiological components, such as flexibility, peak VO2, and reaction time do not differ among female sprinters of different performance levels as represented in the tested groups.

Influence of the time of day on physical performance in patients with coronary artery disease.

The exercise training workload for cardiac patients is determined from the peak heart rate achieved safely during a stress test. Circadian rhythms may play a key role in changing physiological responses to the stress test. Therefore, the purpose of this study was to evaluate the influence of the time of day on cardiopulmonary and metabolic responses in highly trained men with coronary artery disease. A group of 15 patients with coronary artery disease [53.5 (SD 6) years] performed two sessions of graded tests to exhaustion: one session was performed at 10 a.m. and the second at 5 p.m. in randomized order. Treadmill velocity was kept constant at a speed of 4.8 km h-1 starting with an elevation of 0% which was increased thereafter by 2.5% every 3 min. At rest the results revealed that only oxygen uptake was significantly lower (P < 0.05) in the morning compared to that observed in the evening [2.9 (SD 0.4) compared to 3.5 (SD 0.5) ml O2.kg-1.min-1, respectively]. During exercise, differences due to time of day were found in the variables of maximal oxygen uptake which were significantly higher (P < 0.05) in the evening than in the morning [34.2 (SD 2.6) and 40.8 (SD 2.5) ml O2.kg-1.min-1, respectively]. These data indicated that in these well-trained coronary artery disease patients there was a significant time of day effect associated with metabolic responses following stress-testing.

Aerobic capacity and anaerobic threshold of wheelchair basketball players.

This study evaluated the aerobic capacity and anaerobic threshold of national level Israeli wheelchair basketball players. Subjects were tested working on a wheelchair rolling on a motor driven treadmill and on an arm cycle ergometer. Metabolic and cardiopulmonary parameters were measured during graded maximal exercise tests. Blood lactic acid (LA) concentration was measured in the intervals between loads during the test on the wheelchair. Heart rate (HR) and % heart rate reserve (%HRR) corresponding to the anaerobic threshold (4 mM blood LA) were evaluated while working on the wheelchair rolling on a motor driven treadmill. While working on the wheelchair the following peak exercise values were obtained: VO2 = 24.7 ml.kg/min, VE = 92.09 l/min HR = 181.5 b/min and R = 1.22. Values corresponding to the anaerobic threshold were found to be, HR = 139 b/min and %HRR = 57.02. Low correlations were obtained between peak exercise VO2 and VE measured while working on the wheelchair and those measured with arm cycle ergometer (r = 0.57 p = 0.137 and r = 0.4 p = 0.233 respectively). As athletes, subjects in the present study may be classified as having a low aerobic capacity and anaerobic threshold. It is also concluded that the ergometer type may have an important influence on test results.

Left ventricular responses during prolonged treadmill walking with heavy load carriage.

This study examined with metabolic cart and echo-Doppler the influence of different load carriage during 4 h of treadmill walking on left ventricular systolic function, hemodynamics, and cardiovascular responses. Twenty-six aerobically well-trained male subjects (VO2max = 65.2 +/- 5 ml.kg-1.min-1) volunteered for this study. Subjects carried a load of 38 kg during one session and a load of 50 kg during the other session. Following the 4-h exercise in each session, significant (P < 0.05) differences were noted between the 38-kg and 50-kg workloads with regard to VO2: 14.4 +/- 2 and 19 +/- 5 ml.kg-1.min-1; heart rate: 104 +/- 14 and 125 +/- 17 beats.min-1; diastolic blood pressure: 69 +/- 4 and 79 +/- 4 mm Hg; and rate pressure product 140.4 +/- 15 and 173.8 +/- 20 index.10(-2), respectively. No significant differences were noted between the workloads in regard to systolic blood pressure, perceived exertion rating, and aortic valve Doppler indices. We concluded that during prolonged treadmill walking in well-trained young subjects, the additional load above 50% up to 66% of body weight did not change the steady state of left ventricular systolic function, hemodynamics, and cardiovascular responses throughout the course of the 240 min of effort.

Effect of body position on the afterload response during sustained exercise.

Hemodynamic and cardiovascular responses were studied in 80 males (age: 30 +/- 2 years) at rest, and during separate three minute trials of upright and supine isometric deadlift exercise at 30% of maximum voluntary contraction (MVC). MVC did not differ significantly between supine and upright deadlift exercise. In comparison to values at rest, both forms of isometric exercise resulted in significant increases (p less than 0.05) in heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, oxygen uptake, oxygen pulse and double product. In the upright exercise, the values obtained for all of the physiological variables were found to be significantly higher (p less than 0.05) than in the supine exercise. These findings indicate that the upright isometric deadlift produces a higher after-load than the supine maneuver, and that this response may be a good indicator of cardiovascular functioning.

Comparison between end-systolic pressure-volume and end-systolic wall stress in determining left ventricular contractility with increased afterload.

This study compared end-systolic pressure-volume relationship (P/V) versus wall stress index (WS) as a tool for the evaluation of ventricular contractile state during upright isometric exercise. Both indices of contractility exhibit significant (p < 0.001) increase during exercise compared to resting values. The correlation coefficients for the two indices of contractility were r = -0.45 for exercise and r = -0.70 for rest. Both were significant at the p < 0.01 level. The correlation of the difference scores between rest and exercise as computed by both indices was low (-0.20) and insignificant. These data suggest that changes in contractility from rest to exercise as measured by one index do not reflect the pattern of individual differences that are measured by means of the other index. However, from a reliability point of view, it seems appropriate to prefer the use of P/V index over the WS index in order to determine contractile state.

Physiological responses to wrist weights during endurance cycling in normal subjects.

Cardiopulmonary and metabolic responses were studied in 12 healthy males aged 45 +/- 7 yr (mean +/- SD) during 25 min of cycling exercise with (WW) and without (NW) arm swing with wrist weights at 60% and 75% of their maximal heart rate reserve (MHRR). Cycling leg work was adjusted in order to produce a constant 60% and 75% of MHRR during WW and NW sessions. The results revealed that during both exercises the cardiopulmonary and hemodynamic responses were similar. However, during the NW sessions lactic acid (LA) levels were significantly (P less than 0.01) higher than those observed during WW sessions (3.2 +/- 0.9 and 5.4 +/- 1.5 mm.l-1, vs 2.9 +/- 0.9 and 3.8 +/- 1.3 mm.-1), as were ratings of perceived exertion (RPE) (13.2 +/- 1 and 14.4 +/- 0.6, vs 12.2 +/- 1 and 13.4 +/- 1.5). These data indicated a similar pattern of hemodynamic and respiratory responses to NW and WW cycling exercises, while LA and RPE were lower in WW cycling. It is therefore suggested that arm swing with wrist weights may be a beneficial mode of exercise, distributing the workload on a larger muscle mass while maintaining the target heart rate. Thus, it enables a lower reliance on anaerobic metabolism and a lower perceived exertion.