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.

Reexamination of Stewart's quantitative analysis of acid-base status.

To provide experimental verification to Stewart's quantitative approach to acid-base analysis, the effects of acute maximal treadmill exercise (VO2max test) on venous acid base status were studied in 17 male subjects aged 18-23 yr. Venous CO2 tension (PCO2) total plasma proteins ([PTOT]), [H+], and concentrations of strong ions [( Na+], [K+], [Cl-] and lactate ion concentration ([La-]) were measured before and within 1 min post-exercise. Mean post-exercise PCO2, [PTOT], [K+], and [La-] were significantly higher than the corresponding pre-exercise values (P less than 0.05), there was a strong tendency for a significant change in [Na+] (P less than 0.056), and no changes were found in [Cl-]. Changes in venous acid-base status were analyzed quantitatively by applying relevant physicochemical theory. Altered values measured in the independent variables ([PTOT], PCO2, and net strong ion difference, [SID]) were used to calculate the corresponding changes in the dependent quantities. Comparison of individual measured and calculated values for the only one of these that is normally measured, ([H+]), yielded the theoretically expected agreement. PCO2 and [SID] changes accounted for most [H+] changes. These results demonstrate the usefulness of the quantitative approach (i.e., [H+]-PCO2 diagram) in the analysis and in understanding of plasma acid base changes with exercise and in clinical situations.

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.

Effect of training load on OBLA determination.

Fifteen male long-distance runners, 35.9 +/- 8.2 years of age, participated in the study. They had 5.7 +/- 2.3 years of running experience, marathon best time of 2,58:51 +/- 0,14:45 h, 10-km personal record of 37:18 +/- 2:50 min, and maximal aerobic power of 64.6 +/- 5.8 ml.kg-1.min-1. Their 4 mM.l-1 lactate threshold (OBLA) was tested twice in a randomized order: once following a week of light, pre-race-like training, and once after a week of heavy training load. The parameters measured during the OBLA tests were: rating of perceived exertion (RPE), running economy (E), heart rate (HR), respiratory exchange ratio (R), and running velocity at OBLA. Compared with the light load treatment, RPE following the heavy training week rose by 0.8 units, HR and E remained unchanged, and R decreased slightly (0.012). Running velocity at OBLA was raised 0.42 km.h-1 by the heavy training, but a negative correlation was found between this change and the baseline (light load) OBLA velocity (r = -0.57). It is suggested that in athletes the usefulness of OBLA testing, aimed at assessing current performance capacity, could be compromised by lack of control over the immediately preceding training schedules. However, it appears that the susceptibility to the lack of such standardization may be reduced or absent in higher level runners.