The traditional maximal lactate steady state test versus the 5 × 2000 m test.

Here, we compared the maximal lactate steady state velocity (vMLSS) estimated from a single-visit protocol (v5×2000) to the traditional multi-day protocol (vMLSS). Furthermore, we determined whether there was a lactate steady state during the time limits (Tlim) at vMLSS or v5×2000. Eight runners completed a half marathon (HM), the traditional protocol to determine the vMLSS and the 5×2000 m test in a randomised order, and a Tlim at vMLSS and at v5×2000 in a randomised order. The vMLSS (13.56±0.90 km·h - 1) was higher than the v5×2000 (12.93±0.90 km·h - 1, p=0.001) and comparable to the vHM (13.34±0.75 km·h - 1). The vMLSS (r=0.83) and the v5×2000 (r=0.91) were associated with the vHM but were not indicative of the competition pace. The Tlim at vMLSS (64±15 min) was lower than the Tlim at v5×2000 (94±21 min) and the HM time (95±5 min). In both Tlim, lactate was lower at 45 min than upon finishing the effort and was predictive of its duration (p<0.05). Our results indicate that the 5×2000 m test can be equally useful to assess runners as the traditional MLSS protocol and that there is no lactate steady state during the Tlim at vMLSS or at v5×2000.

Cardiac biomarker response to intermittent exercise bouts.

The impact of intermittent exercise on cardiac biomarker release has not been clearly established. In experienced athletes, we examined the acute effect of a heavy resistance training session (n=18 males) and an indoor soccer match (n=21, 11 males, 10 females) on the release of cTnI, cTnT, and NT-proBNP. Biomarkers were assayed from blood samples collected at rest, immediately post- and at 1, 3, 6, 12, and 24 h post-exercise. The heavy resistance training session resulted in an increase in NT-proBNP (pre: 15 ± 17, peak post: 41 ± 56 ng L (-1); p=0.001) but not in cTnI (pre: 0.024 ± 0.009, peak post: 0.025 ± 0.011 µg L (-1), p=0.809) or cTnT (undetectable in all samples). The indoor soccer match led to an increase in the release of NT-proBNP (pre: 28 ± 32, peak post: 66 ± 56 ng L (-1); p=0.000) and cTnI (pre: 0.026 ± 0.047, peak post: 0.033 ± 0.051 µg L (-1); p=0.008) in both males and females but not cTnT (detectable in only one subject). The current data suggest that intermittent bouts of exercise result in only modest perturbations of cardiac biomarkers with very limited evidence of myocyte injury/insult.

The impact of exercise duration and intensity on the release of cardiac biomarkers.

Numerous studies have observed cardiac biomarker release with prolonged exercise. Despite this, we are unsure as to the constituent aspects of any given exercise bout that may be important in promoting cardiac biomarker release. This study examined the influence of exercise duration and intensity on the appearance of cardiac biomarkers. Twenty-one subjects ran for 45, 90 and 180 min at 85% and 95% of their individual anaerobic threshold on six different days randomized. Cardiac troponin I (cTnI) and N-terminal pro-brain natiuretic peptide (NT-proBNP) were assayed from blood samples collected before, 30 min and 3 h post-exercise. NT-proBNP was elevated after all exercise trials (range before: 21-32; range post: 38-67 ng/L). Peak post-exercise concentrations of NT-proBNP were associated with exercise duration (P=0.049), but not exercise intensity (P=0.451). cTnI was elevated after all exercise trials (range before: 0.007-0.011; range post: 0.008-0.021 µg/L). Peak post-exercise concentrations of cTnI were associated with exercise duration (P=0.003) and intensity (P=0.037). Data suggest that while both cTnI and NT-proBNP increased after all exercise trials, the mediating effect of duration influenced both NT-proBNP and cTnI while intensity influenced only cTnI.

The changes in running performance and maximal oxygen uptake after long-term training in elite athletes.

AIM: The relationship between VO2max (mL x kg(-1) x min(-1)) and running performance has been assessed in cross-sectional studies. Follow-up studies of the long-term effects of running training on the changes in performance and VO2max have not been undertaken. METHODS: Twenty-five male endurance-trained (MET) and 8 female endurance-trained (FET) athletes were tracked over 4 years. In each event the athletes were divided into Class A, including half the number of athletes with the best performances, and Class B. VO2max, examined at the end of the competitive season, and the best performance was chosen each year. RESULTS: After 3 years of training, in MET and FET athletes the performance improved by 1.77% and 0.69% (P<0.01 and P=0.579), respectively. In Class A runners, training resulted in non-significant increase in performance (-0.04%) (P=0.982) and in Class B runners, performance increased by 3.16% (P=0.001). In all groups VO(2max) remained essentially unchanged. Longitudinal changes in the VO2max were not related with the changes in running performance in any group. CONCLUSIONS: This study show than in older runners with more years of training, heavy training does not produce improvements in running performance neither changes in the VO2max. It is possible that these elite athletes have reached the plateau in their performance; although unlikely, some improvement in training techniques may happen and break the present limit. In younger runners with less years of training, heavy training produce improvements in running performance without changes in the VO2max. These athletes that had not attained his biological limits at the beginning of study improved the performance in competition and it is quite probable that this improvement be due to training. The changes in performance were not related to changes in VO2max. Consequently, another physiological or psychological variables must be studied by longitudinal form to explain the variability of performance in competition.

Differences in skinfold thicknesses and fat distribution among top-class runners.

AIM: The purpose of this research was to determine skinfolds values in male and female top-class runners who competed in different distances in order to identify the association of sex and event with fatness and distribution of subcutaneous fat. METHODS: Eight skinfolds were measured on male (n=130) and female (n=56) top-class runners. Sum of 6 skinfolds and extremity/trunk fat ratio was calculated. Runners were distributed into groups according to the event in which they obtained their best performance. RESULTS: The skinfolds values found in our athletes were very low. Female runners obtained higher values in extremity skinfolds than male runners; the differences in chest, biceps and abdominal skinfolds are only significant in short duration events; no differences were found in suprailiac and subscapular skinfolds. In both sexes, all skinfolds showed significantly lower values among marathon runners; no differences were found in skinfolds values among runners competing in distances ranging from 100 m to 10,000 m. Extremity/trunk fat ratio was not related to event. CONCLUSIONS: The lower skinfold values found in all groups of runners may be due to a high performance; this analysis shows that a slight excess of fat is not beneficial in order to obtain a high performance in any distance. Fatness is only associated to marathon events, probably due to the fact that these runners are engaged in higher training volume and that only in this event fat metabolism prevails in training and competition. Distribution of subcutaneous fat may be more dependent on biological or environmental factors unrelated to type of training.