Hassane Zouhal

Catecholamines and the Effects of Exercise, Training and Gender

Stress hormones, adrenaline (epinephrine) and noradrenaline (norepinephrine), are responsible for many adaptations both at rest and during exercise. Since their discovery, thousands of studies have focused on these two catecholamines and their importance in many adaptive processes to different stressors such as exercise, hypoglycaemia, hypoxia and heat exposure, and these studies are now well acknowledged. In fact, since adrenaline and noradrenaline are the main hormones whose concentrations increase markedly during exercise, many researchers have worked on the effect of exercise on these amines and reported 1.5 to >20 times basal concentrations depending on exercise characteristics (e.g. duration and intensity). Similarly, several studies have shown that adrenaline and noradrenaline are involved in cardiovascular and respiratory adjustments and in substrate mobilization and utilization. Thus, many studies have focused on physical training and gender effects on catecholamine response to exercise in an effort to verify if significant differences in catecholamine responses to exercise could be partly responsible for the different performances observed between trained and untrained subjects and/or men and women. In fact, previous studies conducted in men have used different types of exercise to compare trained and untrained subjects in response to exercise at the same absolute or relative intensity. Their results were conflicting for a while.As research progressed, parameters such as age, nutritional and emotional state have been found to influence catecholamine concentrations. As a result, most of the recent studies have taken into account all these parameters. Those studies also used very well trained subjects and/or more intense exercise, which is known to have a greater effect on catecholamine response so that differences between trained and untrained subjects are more likely to appear. Most findings then reported a higher adrenaline response to exercise in endurance-trained compared with untrained subjects in response to intense exercise at the same relative intensity as all-out exercise. This phenomenon is referred to as the ‘sports adrenal medulla’. This higher capacity to secrete adrenaline was observed both in response to physical exercise and to other stimuli such as hypoglycaemia and hypoxia. For some authors, this phenomenon can partly explain the higher physical performance observed in trained compared with untrained subjects. More recently, these findings have also been reported in anaerobic-trained subjects in response to supramaximal exercise. In women, studies remain scarce; the results are more conflicting than in men and the physical training type (aerobic or anaerobic) effects on catecholamine response remain to be specified. Conversely, the works undertaken in animals are more unanimous and suggest that physical training can increase the capacity to secrete adrenaline via an increase of the adrenal gland volume and adrenaline content.

Inverse relationship between percentage body weight change and finishing time in 643 forty-two-kilometre marathon runners

Objective The purpose of this study was to determine the relationship between athletic performance and the change in body weight (BW) during a 42 km marathon in a large cohort of runners. Methods The study took place during the 2009 Mont Saint-Michel Marathon (France). 643 marathon finishers (560 males and 83 females) were studied. The change in BW during the race was calculated from measurements of each runners BW immediately before and after the race. Results BW loss was 2.3±2.2% (mean±SEM) (p<0.01). BW loss was −3.1±1.9% for runners finishing the marathon in less than 3 h; −2.5±2.1% for runners finishing between 3 and 4 h; and −1.8±2.4% for runners who required more than 4 h to complete the marathon. The degree of BW loss was linearly related to 42 km race finishing time (p<0.0000001). Neither age nor gender influenced BW loss during the race. Conclusions BW loss during the marathon was inversely related to race finishing time in 643 marathon runners and was >3% in runners completing the race in less than 3 h. These data are not compatible with laboratory-derived data suggesting that BW loss greater than 2% during exercise impairs athletic performance. They match an extensive body of evidence showing that the most successful athletes in marathon and ultra-marathon running and triathlon events are frequently those who lose substantially more than 3–4% BW during competition.

Exercise improves the ApoB/ApoA-I ratio, a marker of the metabolic syndrome in obese children.

Aim:  This study was designed to examine the effect of training on components of the metabolic syndrome and ApoB/ApoA‐I ratio in obese children.

Extreme running competition decreases blood antioxidant defense capacity.

Objective: We tested whether an extreme running competition (“Marathon of Sands”) might alter the blood’s enzymatic and non-enzymatic antioxidant status in 6 well-trained athletes. Methods: The Marathon of Sands is a competition consisting of six long duration races in the desert in which the athletes carry their own food. Blood samples were collected from an antecubital vein while the athletes were at rest before the competition and then again 72 hours after. Erythrocyte antioxidant enzyme activity (glutathione peroxidase, superoxide dismutase), erythrocyte glutathione level, plasma non-enzymatic status (vitamin C, alpha-tocopherol, retinol, β-carotene and carotenoids) and plasma lipid peroxidation marker (TBARS) were measured. Results: The Marathon of Sands induced a significant alteration of the blood antioxidant defense capacity. Indeed, 72 hours after the race, significant decreases were recorded in erythrocyte superoxide dismutase activity and in plasma concentrations of retinol, β-carotene and other carotenoids. These changes were associated with a concomitant increase in erythrocyte glutathione and in plasma TBARS levels. Conclusion: This study indicated that such extreme competition induced an imbalance between oxidant and antioxidant protection.

Effect of Individualized Exercise Training combined with Diet Restriction on Inflammatory Markers and IGF-1/IGFBP-3 in Obese Children

Aims: The present study was designed to examine the possible changes in body composition, insulin-like growth factor 1 (IGF-1), insulin-like growth factor-binding protein-3 (IGFBP-3) and inflammatory markers of obese children in response to a 2-month program of exercise training combined with dietary restriction. Methods: Twenty-eight obese children (age 13.2 ± 0.7 years, body mass index 30.9 ± 1.3) were randomly assigned to a diet/training group or a control group and were tested two times: once before and once at the end of the experimental period. They performed a progressive cycle ergometer test at each visit. Substrate oxidation was evaluated by indirect calorimetry. Training was individualized at the point when fat oxidation was maximal (Lipoxmax). Results: Diet/training induced a significant decrease in body weight and body fat (after vs. before, p < 0.01). Plasma concentrations of IGF-1, IGFBP-3 and inflammatory markers were significantly decreased after the completion of the program. The diet/training program resulted in an increase in VO2maxACSM (24.6 ± 2.5 to 33.1 ± 3.1 ml/min/kg, p < 0.001) at the end of the intervention period. Conclu- sion: These data suggest that in the presence of weight loss, exercise training improves inflammatory markers and IGF-1 and IGFBP-3 levels in obese children.

Effects of Playing Surface (hard and Clay Courts) on Heart Rate and Blood Lactate During Tennis Matches Played by High-level Players

Martin, C, Thevenet, D, Zouhal, H, Mornet, Y, Delès, R, Crestel, T, Ben Abderrahman, A, and Prioux, J. Effects of playing surface (hard and clay courts) on heart rate and blood lactate during tennis matches played by high level players. J Strength Cond Res 25(1): 163-170, 2011-The aim of this study was to compare tennis matches played on clay (CL) and resin (R) courts. Six matches were played (3 on CL courts and 3 on R courts) by 6 high-level players. Heart rate (HR) was monitored continuously while running time (4.66 m), and blood lactate concentration ([La]) were measured every 4 games. Mean duration of points and effective playing time (EPT) were measured for each match. Mean HR (154 ± 12 vs. 141 ± 9 b·min−1) and [La] values (5.7 ± 1.8 vs. 3.6 ± 1.2 mmol·L−1) were significantly higher on CL (p < 0.05). The [La] increased significantly during the match on CL court. Mean duration of rallies (8.5 ± 0.2 vs. 5.9 ± 0.5 seconds) and EPT (26.2 ± 1.9 vs. 19.5 ± 2.0%) were significantly longer (p < 0.05) on CL. Running time values in speed tests were not significantly different between CL and R. Running time performance was not significantly decreased during the match, whatever the playing surface. This study shows that the court surface influences the characteristics of the match and the players physiological responses. The court surface should be a key factor for consideration when coaches determine specific training programs for high-level tennis players.

Intense exercise training induces adaptation in expression and responsiveness of cardiac β-adrenoceptors in diabetic rats

BackgroundInformations about the effects of intense exercise training on diabetes-induced myocardial dysfunctions are lacking. We have examined the effects of intense exercise training on the cardiac function of diabetic rats, especially focusing on the Langendorff β-adrenergic responsiveness and on the β-adrenoceptors protein expression.MethodsControl or Streptozotocin induced-diabetic male Wistar rats were randomly assigned to sedentary or trained groups. The training program consisted of 8 weeks running on a treadmill (10° incline, up to 25 m/min, 60 min/day) and was considered to be intense for diabetic rats.ResultsThis intense exercise training amplified the in vivo diabetes-induced bradycardia. It had no effect on Langendorff basal cardiac contraction and relaxation performances in control and diabetic rats. In diabetic rats, it accentuated the Langendorff reduced responsiveness to β-adrenergic stimulation. It did not blunt the diabetes-induced decrease of β1-adrenoceptors protein expression, displayed a significant decrease in the β2-adrenoceptors protein expression and normalized the β3-adrenoceptors protein expression.ConclusionsIntense exercise training accentuated the decrease in the myocardial responsiveness to β-adrenergic stimulation induced by diabetes. This defect stems principally from the β2-adrenoceptors protein expression reduction. Thus, these results demonstrate that intense exercise training induces specific effects on the β-adrenergic system in diabetes.

Nutritional and Plasmatic Antioxidant Vitamins Status of Ultra Endurance Athletes

Objective: The “Marathon des Sables” (MDS) is a competition known to induce oxidative stress. Antioxidant vitamins prevent exercise-induced oxidative damages. The purpose of this study was to evaluate daily intake and plasma level of the main antioxidant vitamins (α-tocopherol, vitamin C, β-carotene and retinol) in 19 male athletes who participated in this competition. Methods: Data collected before the beginning of the competition included daily dietary intake using a 7-day food record and plasma biochemical measurements (α-tocopherol, vitamin C, β-carotene and retinol). Results: First, total energy intake was obviously lower than the energetic intake usually observed in well-trained endurance athletes. Second, antioxidant vitamins intake was also insufficient. Indeed, the intake was lower than the French Dietary Reference Intakes (DRI) for this population in 18 subjects for vitamin E and 6 subjects for vitamin C, β-carotene and Retinol Equivalent. As a significant relationship was found between total energy intake and the intake of vitamin E (r = 0.73; p < 0.001) and vitamin C (r = 0.78; p < 0.001), the low total energy intake contributed partially to the insufficient antioxidant vitamins intake. The dietary questionnaire analysis also revealed a low intake of vegetable oils, fruits and vegetables. However, plasma concentrations of these antioxidant vitamins were similar to the literature data observed in athletes. Conclusion: This study evidenced obvious insufficient energy intake in ultra endurance athletes associated with a low antioxidant vitamin intake.

Multivitamin-Mineral Supplementation Prevents Lipid Peroxidation during “The Marathon des Sables”

Objective: We investigated the effect of a moderate mutivitamin and mineral supplementation containing mainly vitamin C (150.0 mg.day−1), vitamin E (24.0 mg.day−1) and β-carotene (4.8 mg.day−1) prior to and during an extreme running competition -the Marathon des Sables (MDS)- that consisted of six long races in the desert. Methods: Seventeen athletes participated in our double blind, placebo-controlled study. Blood samples were collected prior to the supplementation i.e. three weeks before the competition (D-21), two days prior to the MDS (D-2), after the third race (D3) and at the end of the competition (D7). Erythrocyte antioxidant enzyme activity (glutathione peroxidase (GPx), superoxide dismutase (SOD)), erythrocyte glutathione level (GSH), plasma non-enzymatic antioxidant status (uric acid, vitamin C, α-tocopherol, retinol, β-carotene), markers of plasma lipid peroxidation (thiobarbituric reactive substances (TBARS)), reactive carbonyl derivatives (RCD) and membrane damage (creatine kinase and lactate dehydrogenase activities) were measured. Results: In both groups, GSH levels, uric acid levels and membrane damage significantly increased during the competition while SOD activity significantly decreased. In Supplemented group, plasma α-tocopherol, β-carotene and retinol levels significantly increased after three weeks of supplementing. In contrast to Placebo group, α-tocopherol, vitamin C and retinol levels were significantly affected by the competition in Supplemented group. Moreover, no increase in TBARS was observed in Supplemented group during the competition, whereas TBARS significantly increased at D3 in the placebo group. Conclusion: The moderate multivitamin-mineral supplementation prevented the transient increase in TBARS levels during this extreme competition.

Two-month effects of individualized exercise training with or without caloric restriction on plasma adipocytokine levels in obese female adolescents

OBJECTIVES To examine if, in young obese patients, an individualized training programme in association with a caloric restriction programme which had an effect on whole-body lipid oxidation, was able to induce changes on plasma adipocytokine concentrations. MATERIALS AND METHODS Twenty-seven obese female adolescents participated in the study. Whole-body lipid oxidation during exercise was assessed by indirect calorimetry during a graded cycle ergometer test. Body mass (BM), body mass index (BMI), percentage of body fat (%BF), insulin homeostasis model assessment (HOMA-IR) and fasting levels of circulating adipocytokines were assessed prior and after a two-month diet programme, individualized training programme targeted at Lipox(max) corresponded to the power at which the highest rate of lipids was oxidized and combined diet/training programme. RESULTS The diet/training programme induced both a shift to a higher-power intensity of Lipox(max) (+27.8 + or - 5.1 W; p<0.01) and an increase of lipid oxidation at Lipox(max) (+96.8 + or - 16.2mg/min; p<0.01). The enhancement in lipid oxidation was significantly (p<0.01) correlated with the diet/training-induced improvement in %BF (r = -0.47), HOMA-IR (r = -0.66), leptin (r = -0.41), TNF-alpha (r = -0.48), IL-6 (r = -0.38), adiponectin (r = 0.43) and resistin (r = 0.51). CONCLUSION This study showed that in obese female adolescents a moderate training protocol targeted at Lipox(max) and combined with a diet programme improved their ability to oxidize lipids during exercise, and that this improvement was associated with changes in plasma adipocytokine concentrations.