Oxygen Uptake, Heart Rate, and Lactate Responses for Continuous Forward Running and Stop-and-Go Running With and Without Directional Changes.

Bekraoui, N, Boussaidi, L, Cazorla, G, and Léger, L. Oxygen uptake, heart rate, and lactate responses for continuous forward running and stop-and-go running with and without directional changes. J Strength Cond Res 34(3): 699-707, 2020-The purpose of this study is to measure and quantify the differences for the gross oxygen uptake (V[Combining Dot Above]O2), heart rate (HR), and blood lactate ([LA]) responses to various modes of in-line running. Twelve healthy participants did an indirect continuous multistage field test to determine the maximal aerobic speed (MAS) before randomly performing in separate sessions 1 of the 3 running protocols at 3 intensities (60, 70, and 80% MAS) (a) in-line continuous running (IR), (b) fractioned running (FR) with stop and go every 20 m, and (c) 20-m shuttle run (SR). V[Combining Dot Above]O2 varied between 34.2 ± 2.5 and 54.6 ± 5.4 ml·kg·min, HR between 141 ± 14 and 184 ± 9 b·min, and [LA] between 4.2 ± 0.8 and 6.6 ± 0.9 mmol·L. In-line continuous running V[Combining Dot Above]O2 was lower than those of SR and FR at all intensities (p < 0.05). However, SR V[Combining Dot Above]O2 were higher than those of FR at 80% MAS only. Heart rate was similar in SR and FR but lower in IR at all intensities (p < 0.05). No significant differences were recorded in [LA]. Because only V[Combining Dot Above]O2 was affected by the introduction of a 180° angle directional change (SR vs. FR) at 80% MAS, the use of HR to assess such activities at such intensities will result in underestimating workloads. This study offers new insights into V[Combining Dot Above]O2, HR, and [LA] associated with accelerations while running with and without directional changes at submaximal speeds.

Validation for quantification of immunoglobulins by Fourier transform infrared spectrometry.

BACKGROUND: The objective of this study was to develop a robust quantification method for simultaneously analyzing molecules in human plasma using the Fourier transform infrared (FT-IR) system with a partial least square (PLS) regression. METHODS: Plasma spectra were analyzed from 4000 to 500 cm(-1) (with 2.0 cm(-1) of resolution and 32 scans), and the molecule concentrations (IgA, IgG, IgM) were measured blindly by using a cross-validation model prepared by PLS analysis of data from 135 samples. RESULTS: There was a significant correlation between the FT-IR predicted concentration and the concentration obtained with the clinical reference method: R(2)=0.98 (IgA), R(2)=0.98 (IgG), and R(2)=0.97 (IgM). The root mean square error of prediction (RMSEP) was 0.05 g.L(-1) (IgA), 0.4 g.L(-1) (IgG), and 0.03 g.L(-1) (IgM). Variability of inter-experimenter reproducibility was less than 2%. The interchangeability of the two methods was studied by using the Bland-Altman method. CONCLUSIONS: Together with PLS analysis, FT-IR spectrometry appears to be an easy-to-use and accurate method to determine multianalyte concentrations in dried human plasma. It could be an alternative tool for rapidly quantifying many molecules after developing a specific predictive model.

Worldwide variation in the performance of children and adolescents: an analysis of 109 studies of the 20-m shuttle run test in 37 countries.

This study is a meta-analysis of 109 reports of the performance of children and adolescents on the 20-m shuttle run test (20-mSRT). The studies were performed in 37 countries and included data on 418,026 children, tested between 1981 and 2003. Results were expressed as running speed (km x h(-1)) at the final completed stage of the 20-mSRT. Raw data were combined with pseudodata using Monte Carlo simulation. The 20-mSRT performances were expressed as z-scores relative to all children of the same age and sex from all countries. An overall "performance index" was derived for each country as the average of the age- and sex-specific z-scores for all children from that country. Factorial analysis of variance was used to compare scores among countries and regions, and between boys and girls of the same age. There was wide and significant (P < 0.0001) global variability in the performance of children. The best performing children were from the Northern European countries Estonia, Iceland, Lithuania, and Finland (0.6 - 0.9 standard deviations above the global average). The worst performing children were from Singapore, Brazil, USA, Italy, Portugal, and Greece (0.4 - 0.9 standard deviations below the global average). There is evidence that performance was negatively related to being overweight, as well as to a country's average temperature.

Secular trends in the performance of children and adolescents (1980-2000): an analysis of 55 studies of the 20m shuttle run test in 11 countries.

It is widely believed that the performance of children and adolescents on aerobic fitness tests is declining. To test this hypothesis, this meta-analysis compared the results of 55 reports of the performance of children and adolescents aged 6-19 years who have used the 20m shuttle run test (20mSRT). All data were collected in the period 1981-2000. Following corrections for methodological variation, the results of all studies were expressed using the common metric of running speed (km/h) at the last completed stage. Raw data were combined with pseudodata generated from reported means and standard deviations using Monte Carlo simulation. Where data were available on children and adolescents from the same country of the same age and sex, but tested at different times, linear regression was used to calculate rates of change. This was possible for 11 (mainly developed) countries, representing a total of 129,882 children and adolescents in 151 age x sex x country slices. There has been a significant decline in performance in the 11 countries where data were available, and in most age x sex groups, with a sample-weighted mean decline of 0.43% of mean values per year. The decline was most marked in older age groups and the rate of decline was similar for boys and girls. There has been a very rapid secular decline in the 20mSRT performance of children and adolescents over the last 20 years, at least in developed countries. The rate of decline is not related to the change in the country's relative wealth, as quantified by per capita gross domestic product (GDP).

Biochemical aspects of overtraining in endurance sports : the metabolism alteration process syndrome.

Recent studies have shown that endurance overtraining could result from successive and cumulative alterations in metabolism, which become chronic during training. The onset of this process is a biochemical alteration in carbohydrate (saccharide) metabolism. During endurance exercises, the amount of saccharide chains from two blood glycoproteins (alpha(2)-macroglobulin and alpha(1)-acid glycoprotein) was found to have decreased, i.e. concentrations of these proteins remained unchanged but their quality changed. These saccharide chains were probably used for burning liver glycogen stores during exercise. This step was followed by alterations in lipid metabolism. The most relevant aspect of this step was that the mean chain length of blood fatty acids decreased, i.e. the same amount of fatty acids were found within the blood, but overtrained individuals presented shorter fatty acids than well-trained individuals. This suggests that alterations appeared in the liver synthesis of long-chain fatty acids or that higher peroxidation of blood lipoparticles occurred. For the final step of this overtraining process, it was found that these dysfunctions in carbohydrate/lipid metabolism led to the higher use of amino acids, which probably resulted from protein catabolism. The evolution of three protein concentrations (alpha(1)-acid glycoprotein, alpha(2)-macroglobulin and IgG(3)) correlated with this amino acid concentration increase, suggesting a specific catabolism of these proteins. At this time only, overtraining was clinically diagnosed through conventional symptoms. Therefore, this process described successive alterations in exercise metabolism that shifted from the main energetic stores of exercise (carbohydrates and lipids) towards molecular pools (proteins) normally not substantially used for the energetic supply of skeletal muscles. Now, a general biochemical model of the overtraining process may be proposed which includes most of the previously identified metabolic hypotheses.

Biochemical aspects of overtraining in endurance sports: a review.

Top-level performances in endurance sports require several years of hard training loads. A major objective of this endurance training is to reach the most elevated metabolic adaptations the athlete will be able to support. As a consequence, overtraining is a recurrent problem that highly-trained athletes may experience during their career. Many studies have revealed that overtraining could be highlighted by various biochemical markers but a principal discrepancy in the diagnosis of overtraining stems from the fact that none of these markers may be considered as universal. In endurance sports, the metabolic aspects of training fatigue appear to be the most relevant parameters that may characterise overtraining when recovery is not sufficient, or when dietary habits do not allow an optimal replenishment of substrate stores. From the skeletal muscle functions to the overall energetic substrate availability during exercise, six metabolic schemes have been studied in relation to overtraining, each one related to a central parameter, i.e. carbohydrates, branched-chain amino acids, glutamine, polyunsaturated fatty acids, leptin, and proteins. We summarise the current knowledge on these metabolic hypotheses regarding the occurrence of overtraining in endurance sports.