The cardioprotective effect of a short-term aerobic exercise program and the mitochondrial permeability transition pore of the Rat

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The cardioprotective effect of a short-term aerobic exercise program and the mitochondrial permeability transition pore of the Rat

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Aerobic and anaerobic test performance among elite male football players in different team positions

The purpose was to determine the magnitude of aerobic and anaerobic performance factors among elite male football players in different team positions. Thirty-nine players from the highest Swedish division classified as defenders (n=18), midfield players (n=12) or attackers (n=9) participated. Their mean (± sd) age, height and body mass (bm) were 24.4 (±4.7) years, 1.80 (±5.9)m and 79 (±7.6)kg, respectively. Running economy (RE) and anaerobic threshold (AT) was determined at 10, 12, 14, and 16km/h followed by tests of maximal oxygen uptake (VO2max). Maximal strength (1RM) and average power output (AP) was performed in squat lifting. Squat jump (SJ), counter-movement jump with free arm swing (CMJa), 45m maximal sprint and the Wingate test was performed. Average VO2max for the whole population (WP) was 57.0mL O2•kg-1min-1 . The average AT occurred at about 84% of VO2max. 1RM per kg bm0.67 was 11.9±1.3kg. Average squat power in the whole population at 40% 1RM was 70±9.5W per kg bm0.67 . SJ and CMJa were 38.6±3.8cm and 48.9±4.4cm, respectively. The average sprint time (45m) was 5.78± 0.16s. The AP in the Wingate test was 10.6±0.9W•kg-1 . The average maximal oxygen uptake among players in the highest Swedish division was lower compared to international elite players but the Swedish players were better off concerning the anaerobic threshold and in the anaerobic tests. No significant differences were revealed between defenders, midfielders or attackers concerning the tested parameters presented above.

Running economy and blood lactate accumulation in elite football players with high and low maximal aerobic power

The purpose was to determine running economy and lactate threshold among a selection of male elite football players with high and low aerobic power. Forty male elite football players from the highest Swedish division (“Allsvenskan”) participated in the study. In a test of running economy (RE) and blood lactate accumulation the participants ran four minutes each at 10, 12, 14, and 16 km•h-1 at horizontal level with one minute rest in between each four minutes interval. After the last sub-maximal speed level the participants got two minutes of rest before test of maximal oxygen uptake (VO2max). Players that had a maximal oxygen uptake lower than the average for the total population of 57.0 mL O2•kg-1•minute-1 were assigned to the low aerobic power group (LAP) (n=17). The players that had a VO2max equal to or higher than 57.0 mL O2•kg-1•minute-1 were selected for the high aerobic power group (HAP) (n=23). The VO2max was significantly different between the HAP and LAP group. The average RE, measured as oxygen uptake at 12, 14 and 16km•h-1 was significantly lower but the blood lactate concentration was significantly higher at 14 and 16 km•h-1 for theLAP group compared with the HAP group.

Aerobic and anaerobic test performance among elite male football players in different team positions

The purpose was to determine the magnitude of aerobic and anaerobic performance factors among elite male football players in different team positions. Thirty-nine players from the highest Swedish division classified as defenders (n=18), midfield players (n=12) or attackers (n=9) participated. Their mean (± sd) age, height and body mass (bm) were 24.4 (±4.7) years, 1.80 (±5.9)m and 79 (±7.6)kg, respectively. Running economy (RE) and anaerobic threshold (AT) was determined at 10, 12, 14, and 16km/h followed by tests of maximal oxygen uptake (VO2max). Maximal strength (1RM) and average power output (AP) was performed in squat lifting. Squat jump (SJ), counter-movement jump with free arm swing (CMJa), 45m maximal sprint and the Wingate test was performed. Average VO2max for the whole population (WP) was 57.0mL O2•kg-1min-1. The average AT occurred at about 84% of VO2max. 1RM per kg bm0.67 was 11.9±1.3kg. Average squat power in the whole population at 40% 1RM was70±9.5W per kg bm0.67. SJ and CMJa were 38.6±3.8cm and 48.9±4.4cm,respectively. The average sprint time (45m) was 5.78± 0.16s. The AP in the Wingate test was 10.6±0.9W•kg-1. The average maximal oxygen uptake among players in the highest Swedish division was lower compared to international elite players but the Swedish players were better off concerning the anaerobic threshold and in the anaerobic tests. No significant differences were revealed between defenders, midfielders or attackers concerning the tested parameters presented above.

Effects of a 12-week aerobic exercise intervention on eating behaviour, food cravings and 7-day energy intake and energy expenditure in inactive men

This study examined effects of 12 weeks of moderate-intensity aerobic exercise on eating behaviour, food cravings and weekly energy intake and expenditure in inactive men. Eleven healthy men (mean ± SD: age, 26 ± 5 years; body mass index, 24.6 ± 3.8 kg/m2; maximum oxygen uptake, 43.1 ± 7.4 mL/kg/min) completed the 12-week supervised exercise programme. Body composition, health markers (e.g. blood pressure), eating behaviour, food cravings and weekly energy intake and expenditure were assessed before and after the exercise intervention. There were no intervention effects on weekly free-living energy intake (p=0.326, d=-0.12) and expenditure (p=0.799, d=0.04), or uncontrolled eating and emotional eating scores (p>0.05). However, there was a trend with a medium effect size (p=0.058, d=0.68) for cognitive restraint to be greater after the exercise intervention. Total food cravings (p=0.009, d=-1.19) and specific cravings of high-fat foods (p=0.023, d=-0.90), fast-food fats (p=0.009, d=-0.71) and carbohydrates/starches (p=0.009, d=-0.56) decreased from baseline to 12 weeks. Moreover, there was a trend with a large effect size for cravings of sweets (p=0.052, d=-0.86) to be lower after the exercise intervention. In summary, 12 weeks of moderate-intensity aerobic exercise reduced food cravings and increased cognitive restraint, however, these were not accompanied by changes in other eating behaviours and weekly energy intake and expenditure. The results indicate the importance of exercising for health improvements even when reductions in body mass are modest.

Cardiorespiratory fitness and aerobic performance adaptations to a 4-week sprint interval training in young healthy untrained females

Purpose The aim of this study was to test the effects of sprint interval training (SIT) on cardiorespiratory fitness and aerobic performance measures in young females. Methods Eight healthy, untrained females (age 21 ± 1 years; height 165 ± 5 cm; body mass 63 ± 6 kg) completed cycling peak oxygen uptake ( V˙O2V˙O2 peak), 10-km cycling time trial (TT) and critical power (CP) tests pre- and post-SIT. SIT protocol included 4 × 30-s “all-out” cycling efforts against 7 % body mass interspersed with 4 min of active recovery performed twice per week for 4 weeks (eight sessions in total). Results There was no significant difference in V˙O2V˙O2 peak following SIT compared to the control period (control period: 31.7 ± 3.0 ml kg−1 min−1; post-SIT: 30.9 ± 4.5 ml kg−1 min−1; p > 0.05), but SIT significantly improved time to exhaustion (TTE) (control period: 710 ± 101 s; post-SIT: 798 ± 127 s; p = 0.00), 10-km cycling TT (control period: 1055 ± 129 s; post-SIT: 997 ± 110 s; p = 0.004) and CP (control period: 1.8 ± 0.3 W kg−1; post-SIT: 2.3 ± 0.6 W kg−1; p = 0.01). Conclusions These results demonstrate that young untrained females are responsive to SIT as measured by TTE, 10-km cycling TT and CP tests. However, eight sessions of SIT over 4 weeks are not enough to provide sufficient training stimulus to increase V˙O2V˙O2 peak.

A neuroimaging investigation of the association between aerobic fitness, hippocampal volume and memory performance in preadolescent children

Because children are becoming increasingly overweight, unhealthy and unfit, understanding the neurocognitive benefits of an active lifestyle in childhood has important public health and educational implications. Animal research has indicated that aerobic exercise is related to increased cell proliferation and survival in the hippocampus as well as enhanced hippocampal-dependent learning and memory. Recent evidence extends this relationship to elderly humans by suggesting that high aerobic fitness levels in older adults are associated with increased hippocampal volume and superior memory performance. The present study aimed to further extend the link between fitness, hippocampal volume, and memory to a sample of preadolescent children. To this end, magnetic resonance imaging was employed to investigate whether high- and low-fit 9- and 10-year-old children showed differences in hippocampal volume and if the differences were related to performance on an item and relational memory task. Relational but not item memory is primarily supported by the hippocampus. Consistent with predictions, high-fit children showed greater bilateral hippocampal volumes. Furthermore, hippocampal volume was positively associated with performance on the relational but not the item memory task. The findings are the first to suggest that aerobic fitness can impact the structure and function of the developing human brain.

Aerobic performance and morphological modifications after a 4 month physical activity training program in elderly women

Research clearly shows that physical activity (PA) is an important factor to develop and maintain good health and adequate body functions in older people. In this context, the purpose of this study was to determine aerobic performance and morphological modifications after a 4 month physical activity program (PAP) in elderly. METHODS Forty subjects divided in two groups (control, n=20; and experimental, n=20) were evaluated twice, at the beginning and after a 4-month-activity program period. This program called “+ age + health” consists of 3 week sessions of one hour each, based on walking and aerobic exercises. The control group had, at its first evaluation, the followings characteristics: average body mass 68kg±15, 28±5 BMI, 37%±5 body fat, 2.2kg±0.4 bone mass, 42%±9 lean body mass and did 129 repetitions ± 46 on a 2-Minute Step Test (2MST). The assessment of anthropometric and morphological variables was measured through an electrical bioimpedance scale (TANITA - BC 545). Aerobic endurance was evaluated from a 2MST.RESULTS In the control group only the percentage of body fat changed significantly, and increased over time. In the experimental group we found a positive relationship between PAP and the majority of morphological variables. The percentage of variation changed in: body fat (-4.3%±7.6, p=0.014), bone mass (2.4%±3.1, p=0.004) and 2MST (33.6%±63.1, p=0.023). In the remaining variables there were no significant modifications. The significant modification in 2MST after the activity period means that the aerobic performance can be improved in elderly, and attenuates the negative effects of age. Moreover, the benefits of PAP can be seen by positive alterations registered in lean body mass and in the percentage of body fat.

Plasma inflammatory biomarkers response to aerobic versus resisted exercise training for chronic obstructive pulmonary disease patients.

Background: Chronic obstructive pulmonary disease (COPD) is a main risk for morbidity, associated with alterations in systemic inflammation. Recent studies proved that morbidity and mortality of COPD is related to systemic inflammation as it contributes to the pathogenesis of atherosclerosis and cardiovascular disease. However, increase of inflammatory cytokines adversely affects quality of life, alteration in ventilatory and skeletal muscles functions. Moreover, exercise training has many beneficial effects in correction of the adverse effects of COPD. Objective: This study aimed to compare the response of inflammatory cytokines of COPD to aerobic versus resisted exercises. Materials and methods: One hundred COPD diseased patients participated in this study and were randomly included in two groups; the first group received aerobic exercise, whereas the second group received resisted exercise training for 12 weeks. Results: The mean values of TNF-α, Il-2, IL-4, IL-6 and CRP were significantly decreased in both groups. Also; there was a significant difference between both groups at the end of the study with more reduction in patients who received aerobic exercise training. Conclusion: Aerobic exercise is more appropriate than resisted exercise training in modulating inflammatory cytokines level in patients with chronic obstructive pulmonary disease.

Aerobic endurance in HIV-positive young adults and HIV-negative controls in Malawi

Background Aerobic endurance is an important aspect of physical fitness that enables individuals living with HIV to endure in the work place as well as in agricultural operations in order to earn a living and improve their quality of life. However, despite high HIV prevalence rates, the aerobic endurance status of young Malawians living with HIV remains unknown. The objective of this study was to determine the difference in VO2max between HIV-negative and HIV-positive individuals in Blantyre, Malawi. Methods Fifty five participants (17 males and 38 females) who have HIV and were not taking antiretroviral medication and 78 HIV-negative participants (45 males and 33 females) performed the Rockport submaximal treadmill exercise test. Measures of body weight, post-exercise heart rate and time to walk one mile were obtained and used to predict VO2max. Comparisons between groups were adjusted for age differences using analysis of covariance (ANCOVA). Results VO2max was significantly lower in HIV-positive subjects [31.1, 28.7 - 33.5mL.kg-1.min-1(mean, 95% CI)] compared with HIV-negative subjects [56.2, 54.3 - 58.1mL.kg-1.min-1]. Conclusion Aerobic endurance was markedly reduced in HIV-positive participants compared with HIV-negative participants. Findings of the current study implicate factors associated with the HIV infection as contributors to a decreased aerobic endurance in people living with HIV.

Analysis of the aerobic-anaerobic transition in elite cyclists during incremental exercise with the use of electromyography

To investigate the validity and reliability of surface electromyography (EMG) as a new non-invasive determinant of the metabolic response to incremental exercise in elite cyclists. The relation between EMG activity and other more conventional methods for analysing the aerobic-anaerobic transition such as blood lactate measurements (lactate threshold (LT) and onset of blood lactate accumulation (OBLA)) and ventilatory parameters (ventilatory thresholds 1 and 2 (VT1 and VT2)) was studied.Twenty eight elite road cyclists (age 24 (4) years; VO2MAX 69.9 (6.4) ml/kg/min; values mean (SD)) were selected as subjects. Each of them performed a ramp protocol (starting at 0 W, with increases of 5 W every 12 seconds) on a cycle ergometer (validity study). In addition, 15 of them performed the same test twice (reliability study). During the tests, data on gas exchange and blood lactate levels were collected to determine VT1, VT2, LT, and OBLA. The root mean squares of EMG signals (rms-EMG) were recorded from both the vastus lateralis and the rectus femoris at each intensity using surface electrodes. Results - A two threshold response was detected in the rms-EMG recordings from both muscles in 90% of subjects, with two breakpoints, EMG(T1) and EMG(T2), at around 60-70% and 80-90% of VO2MAX respectively. The results of the reliability study showed no significant differences (p > 0.05) between mean values of EMG(T1) and EMG(T2) obtained in both tests. Furthermore, no significant differences (p > 0.05) existed between mean values of EMG(T1), in the vastus lateralis and rectus femoris, and VT1 and LT (62.8 (14.5) and 69.0 (6.2) and 64.6 (6.4) and 68.7 (8.2)% of VO2MAX respectively), or between mean values of EMG(T2), in the vastus lateralis and rectus femoris, and VT2 and OBLA (86.9 (9.0) and 88.0 (6.2) and 84.6 (6.5) and 87.7 (6.4)% of VO2MAX respectively). Rms-EMG may be a useful complementary non-invasive method for analysing the aerobic-anaerobic transition (ventilatory and lactate thresholds) in elite cyclists.

Aerobic power and lean mass are indicators of competitive sprint performance among elite female cross-country skiers

The purpose of this study was to establish the optimal allometric models to predict International Ski Federation’s ski-ranking points for sprint competitions (FISsprint) among elite female cross-country skiers based on maximal oxygen uptake (V̇O2max) and lean mass (LM). Ten elite female cross-country skiers (age: 24.5±2.8 years [mean ± SD]) completed a treadmill roller-skiing test to determine V̇O2max (ie, aerobic power) using the diagonal stride technique, whereas LM (ie, a surrogate indicator of anaerobic capacity) was determined by dual-emission X-ray anthropometry. The subjects’ FISsprint were used as competitive performance measures. Power function modeling was used to predict the skiers’ FISsprint based on V̇O2max, LM, and body mass. The subjects’ test and performance data were as follows: V̇O2max, 4.0±0.3 L min-1; LM, 48.9±4.4 kg; body mass, 64.0±5.2 kg; and FISsprint, 116.4±59.6 points. The following power function models were established for the prediction of FISsprint: 3.91×105 ∙ VO -6.002maxand 6.95×1010 ∙ LM-5.25; these models explained 66% (P=0.0043) and 52% (P=0.019), respectively, of the variance in the FISsprint. Body mass failed to contribute to both models; hence, the models are based on V̇O2max and LM expressed absolutely. The results demonstrate that the physiological variables that reflect aerobic power and anaerobic capacity are important indicators of competitive sprint performance among elite female skiers. To accurately indicate performance capability among elite female skiers, the presented power function models should be used. Skiers whose V̇O2max differs by 1% will differ in their FISsprint by 5.8%, whereas the corresponding 1% difference in LM is related to an FISsprint difference of 5.1%, where both differences are in favor of the skier with higher V̇O2max or LM. It is recommended that coaches use the absolute expression of these variables to monitor skiers’ performance-related training adaptations linked to changes in aerobic power and anaerobic capacity.