Biomedical subjects

T Busso

Publications and source records attributed to T Busso.

26 records · Page 2Linked to original sources

PubMed1995

Influence of hypoxic ventilatory response on arterial O2 saturation during maximal exercise in acute hypoxia.

The aim of this study was to evaluate the influence of peripheral chemosensitivity estimated by hypoxic ventilatory response (HVR) on arterial oxygen saturation (SaO2) during maximal exercise in acute hypoxia. A group of 16 healthy men performed maximal exercise in two conditions of partial pressure of inspired oxygen (PIO2/149 and 70 mm Hg, 19.8 and 9.3 kPa). Measurements of maximal oxygen uptake (VO2max) and SaO2 using an ear-oximeter were carried out in both conditions of PIO2. The HVR was measured at rest by progressive isocapnic hypoxia and evaluated by the slope of the linear regression between the ventilatory flow (VE) and the SaO2 (delta VE/delta SaO2). The absolute value of HVR (in litres per minute per percentage saturation per kilogram) was correlated to maximal expired VE (r = 0.85, P < 0.001), ventilatory equivalent for CO2 (r = 0.83, P < 0.001) and SaO2 (r = 0.60, P < 0.05) determined during maximal exercise in hypoxia: a significant decrease in VO2max (37%) and SaO2 (32%) for PIO2 of 70 mm Hg (9.3 Pa) was observed (P < 0.001). The correlation between the decline of VO2max and arterial oxygen desaturation failed to reach statistical significance (r = 0.47, P = 0.1). The present findings indicated that the peripheral ventilatory chemosensitivity contributed to the interindividual variability of VE and SaO2 during maximal exercise in acute hypoxia.

Adult↗

PubMed1995

Effects of training on performance in competitive swimming.

The relationships between the mean intensity of a training season, training volume and frequency, and the variations in performance were studied in a group of 18 elite swimmers. Additionally, differences between the swimmers who improved their personal record of the previous year during the follow-up training season (GIR, n = 8) and those who did not (GNI, n = 10) were investigated. The improvement in performance during the follow-up season was significantly correlated with the mean intensity of the training season (r = 0.69, p < 0.01), but not with training volume or frequency. The performance improvement during the follow-up season was negatively related to the initial performance level (r = 0.90, p < 0.01). The decline in performance during detraining from the previous year was less for the GIR than for the GNI (6.21 +/- 2.30% vs. 9.79 +/- 2.18%, p < 0.01). The present findings suggest that training intensity is the key factor in performance improvement in a group of elite swimmers. Factors such as previous detraining and initial performance level could jeopardize success in spite of a good adaptation to training.

Adaptation, Physiological↗

PubMed1995

Relationship between mean habitual daily energy expenditure and maximal oxygen uptake.

A population of 120 healthy voluntary subjects of both genders aged 16-88 was studied using the QAPSE (Saint-Etienne Physical Activity Questionnaire) with the purpose of investigating the factors influencing the relation between MHDEE (mean habitual daily energy expenditure) and VO2max (maximal oxygen uptake) to elucidate the factors accounting for individual variation. The mean of MHDEE obtained was 12,181.9 +/- 4041.9 kJ.d-1. The mean VO2max obtained was 39.9 +/- 13.8 ml.kg-1.min-1. A strong relationship between MHDEE and VO2max (r = 0.916; N = 120; P < 0.0001) was found. Further, MHDEE seemed to be the greater determinant in the variation of VO2max (89.35%). Other variables were found to be involved in the relation between MHDEE and VO2max for a smaller, but still substantial part: age (6.92%), PAST (exathletes who had considerably reduced or stopped their training) (2.45%), body mass (0.85%), and gender (0.43%). Two variables regarding maximal intensity of activity were not included in the multiple-linear regression analysis. These results suggested that the most important factor in the variation of VO2max is the total quantity of energy expenditure and not only the maximal intensity that could reach the subject.

Activities of Daily Living↗

PubMed1994

Fatigue and fitness modelled from the effects of training on performance.

The purpose of this study was to compare two ways of estimating both fatigue and fitness indicators from a systems model of the effects of training on performance. The model was applied to data concerning the training of a hammer thrower. The variations in performance were mathematically related to the successive amounts of training. The model equation was composed of negative (NF) and positive (PF) functions. The NF and PF were associated with the fatigue and fitness estimated in previous studies. Using another method, fatigue and fitness indicators were estimated from a combination of NF and PF. The influence of training on performance was negatively associated with fatigue (NI), and positively to fitness (PI). The changes in performance were well described by the model in the present study (r = 0.96, N = 19, P < 0.001). Significant correlations were observed between PF and PI (r = 0.90, P < 0.001) on the other. The absolute values and the time variations of PI and NI were closer to the change in performance than NF and PF. The NF and PF were accounted for mainly by the accumulation of amounts of training. On the other hand, NI and PI were accounted for rather by the impact of these amounts of training on performance.

Adaptation, Physiological↗

PubMed1992

Hormonal adaptations and modelled responses in elite weightlifters during 6 weeks of training.

The concentrations of serum testosterone, sex-hormone-binding-globulin (SHBG) and luteinizing hormone (LH) were examined throughout 1-year of training in six elite weightlifters. A systems model, providing an estimation of fatigue and fitness, was applied to records of training volume and performance levels in clean and jerk. The analysis focused on a 6-week training period during which blood samples were taken at 2-week intervals. A 4-week period of intensive training (period I) could be distinguished from the following 2-week period of reduced training (period II). During period I, decreases in serum testosterone (P less than 0.05) and increases in serum LH concentrations (P less than 0.01) were observed; a significant correlation (r = 0.90, P less than 0.05) was also observed between the changes in serum LH concentration and in estimated fitness. The magnitude of LH response was not related to the change in serum androgens. On the other hand, the change in testosterone:SHBG ratio during period II was significantly correlated (r = 0.97, P less than 0.01) to the LH variations during period I. These finding suggested that the LH response indicated that the decrease in testosterone concentration was not primarily due to a dysfunction of the hypothalamic-pituitary system control, and that the fatigue/fitness status of an athlete could have influenced the LH response to the decreased testosterone concentration. The negative effect of training on hormonal balance could have been amplified by its influence on the hypothalamic-pituitary axis. A decrease in physiological stress would thus have been necessary for the completion of the effect of LH release on androgenic activity.

Humans↗

PubMed1992

Effects of training on iron status in cross-country skiers.

Haematological changes were studied in cross-country skiers during a 33-week training season (7 h a week). The daily amounts of training were calculated from the duration and the intensity of the exercise and then used to estimate training responses associated with a first order transfer function. The profile of system training responses (STR) was determined by convolution between the amounts of training and a first-order transfer function. Linear regressions were used to determine correlation coefficients between STR and iron status indices. Among the values for the time constants of decay, the one giving the best fit between STR and iron status indices was chosen. A relationship was noted between on the one hand STR and changes in serum ferritin concentration ([FERR]) and on the other hand STR and change in mean cell volume (MCV). The [FERR] was decreased and MCV was increased by training. It is suggested that a decrease in [FERR] could have been related to a decrease in total body iron stores. However, large and rapid changes in [FERR] could not have been a reflection of changes in total body iron stores. Equilibrium between [FERR] and total body iron stores could have been temporarily altered by the effects of training. Moreover, iron stores did not seem to have been sufficiently depleted to restrict erythropoiesis. The MCV increased slightly in response to intense training suggesting that training enhances the proportion of young erythrocytes.

Adolescent↗

PubMed1991

Adequacy of a systems structure in the modeling of training effects on performance.

A systems model of training effects on performance was applied to eight initially untrained subjects who were volunteers for an endurance training program for the purpose of verifying the statistical adequacy of the systems structure. In the model initially proposed by T. W. Calvert, E. W. Banister, M. V. Savage, and T. Bach (IEEE Trans. Syst. Man Cybern. 6: 94-102, 1976), the performance changes were related to the successive training loads by three first-order transfer functions. In the present study, the number of first-order components was statistically tested. A model including only one component, which had a positive effect on the performance, provided a significant fit with the performances in every subject. A second component significantly improved the fit in only two subjects. This further component, which had a negative effect on performance, was identified as fatigue. Nevertheless, a two-antagonistic component model is proposed to provide a good representation of the training responses. However, the low level of exercise demands and the inaccuracy of the fit could have impaired the evidencing of a fatiguing effect during the presently studied training protocol.

Adult↗

PubMed1990

A systems model of training responses and its relationship to hormonal responses in elite weight-lifters.

A systems model, providing an estimation of fatigue and fitness levels was applied to a 1-year training period of six elite weight-lifters. The model parameters were individually determined by fitting the predicted performance (calculated as the difference between fitness and fatigue) to the actual one. The purpose of this study was to validate the systems model by comparing the estimated levels of fatigue and fitness with biological parameters external to the model calculation. The predicted and the actual performances were significantly correlated in each subject. The calculated fitness and fatigue levels were related to serum testosterone concentration, testosterone: cortisol and testosterone: sex hormone binding globulin ratios. The best results were obtained by the comparison between fitness and testosterone levels, which varied in parallel in each subject. In two subjects this correlation was significant (r = 0.91, P less than 0.05, and r = 0.92, P less than 0.01). The fitness changes calculated in each subject between the 15th and the 51st weeks of training were significantly correlated with the changes in serum testosterone concentration measured in the same period (r = 0.99, P less than 0.001). For the whole group testosterone and fitness variations were also significantly intercorrelated (r = 0.73, P less than 0.001). Correlations, less homogeneous and less significant, were calculated also for other hormones and ratios. These results suggest that (1) the relationships between training and performance can be described by the systems model, (2) the estimated index of fitness has a physiological meaning. The fatigue index remains to be clarified.

Adult↗