Modification de la lipolyse du tissu adipeux après un entraînement en endurance chez des sujets obèses

This study investigates the effect of a 3 month endurance training on in vitro adipose tissue lipolysis in 13 obese men (body mass index: 36.9 ± 1.3 kg/m²). Training decreased body fat mass percentage (P < 0.05), without body weight change. Lipolytic effects of epinephrine, isoproterenol (β-adrenoceptor agonist) and dobutamine (β₁-adrenoceptor agonist) were significantly increased (P< 0.05). Antilipolytic effects of α₂-adrenoceptor and insulin were significantly decreased (P < 0.05). Endurance training in obese men enhances adipose tissue lipolysis through β-adrenergic pathway, and decreases antilipolytic activity.     

Activité physique adaptée et qualité de vie liée à la santé lors d’un séjour hospitalier chez des enfants atteints d’un cancer : APOP, un essai randomisé en cross-over

Introduction

The objective was to assess the efficacy of adapted physical activity on quality of life of hospitalized children and adolescents with cancer.

Facts

Thirty children were included in the APOP study (mean age 13.6 ± 2.9 years; 18 males). Cross-over analysis revealed no effect of period or interaction between physical activity and period. Quality of life was higher when children practiced than when they did not practice physical activity during their hospitalization, as reported by both children and parents, for the dimensions of physical functioning (P < 0.0001), role/social-physical limitations (P = 0.001), self-esteem (P < 0.0001) and mental health (P < 0.0001). Physical activity had a significant effect on the general behavior dimension (P = 0.01), as reported by children, and on the bodily pain dimension (P = 0.0004), as reported by parents.

Conclusion

Physical activity practiced during hospitalization for children with cancer was associated with better health-related quality of life.     

Exploration détaillée des composantes de la glycorégulation chez des sportifs sujets aux hypoglycémies d’effort. Intérêt de l’oral minimal model

Context

Exercise hypoglycaemia (EH) is a very common yet little studied condition. It occurs in subjects with high values of insulin sensitivity (S_I) and glucose effectiveness (S_G), and is mainly triggered by dietary errors, over-training, or special circumstances (exposure to unusual temperatures, altitude, disruption of circadian rhythms).

Methods and results

We showed that S_I and S_G can be calculated from test meals by mathematical modelling (oral minimal model), whereas in athletes “surrogates” of S_I (HOMA, QUICKI, etc.) are misleading (not applicable in this area of high insulin sensitivity). These meals can also provide a comprehensive picture of the components of insulin secretion, which makes this exploration more informative. We studied the results obtained by this method in 19 athletes complaining of EH compared to 58 matched athletes not complaining from this problem. We observed higher values of S_I (P < 0.05) and S_G (P < 0.03), but overall, insulin secretion Φ_oral was similar. However, one of the components of insulin secretion, β-cell glucose sensitivity, is higher on the average (P < 0.04) because in 30% of cases it remains above the normal range for athletes, while remaining in the range for a normal population. Therefore, overall tolerance to carbohydrates (product Φ_oral × S_I) is higher (+58% P < 0.04).

Conclusion

Thus, these subjects have a powerful carbohydrate disposal, which is incompletely compensated by the expected homeostatic decrease in insulin secretion, especially with regard to β-cell glucose sensitivity.     

Suivi de l’entraînement de nageurs de haut niveau par questionnaire de fatigue, dosages hormonaux et variabilité de la fréquence cardiaqueTraining follow up by questionnaire fatigue, hormones and heart rate variability measurements

Introduction. – A short questionnaire of fatigue, urinary cortisol/cortisone ratio and heart rate variability were measured in 14 elite swimmers during heavy, light and moderate training periods.Results. – The questionnaire was strongly related to the variations of training and performance (r > 0.70). Correlations were lower with the hormonal ratio and insignificant with the heart rate variability.Conclusion. – The questionnaire and the hormonal ratio were good markers of the variations of training and performance contrary to the heart rate variability.     

Specific muscle adaptations in type II fibers after high‐intensity interval training of well‐trained runners

High‐intensity interval training (HIIT) forms an important component of endurance athletes' training, but little is known on intramuscular metabolic and fiber type adaptations. This study investigated physiological and skeletal muscle adaptations in endurance runners subjected to 6 weeks HIIT. Eighteen well‐trained endurance athletes were subjected to 6 weeks HIIT. Maximal and submaximal exercise tests and muscle biopsies were performed before and after training. Results indicated that peak treadmill speed (PTS) increased (21.0 ± 0.8 vs 22.1 ± 1.2 km/h, P<0.001) and plasma lactate decreased at 64% and 80% PTS (P<0.05) after HIIT. Cross‐sectional area of type II fibers tended to have decreased (P=0.06). No changes were observed in maximal oxygen consumption, muscle fiber type, capillary supply, citrate synthase and 3‐hydroxyacetyl CoA dehydrogenase activities. Lactate dehydrogenase (LDH) activity increased in homogenate (P<0.05) and type IIa fiber pools (9.3%, P<0.05). The change in the latter correlated with an absolute interval training speed (r=0.65; P<0.05). In conclusion, HIIT in trained endurance runners causes no adaptations in muscle oxidative capacity but increased LDH activity, especially in type IIa fibers and in relation to absolute HIIT speed.     

Effets de la reprise d’une activité physique régulière sur les capacités physiques et la qualité de vie d’hommes atteints du syndrome métabolique

Objective

To assess the effects of aerobic training on physical capacities and quality of life in men with metabolic syndrome (Mets), using field evaluation tools.

Synthesis

The physical capacities and the quality of life of eight men with Mets (59.5 ± 4.8 years old) was assessed before and after 8 weeks of aerobic exercise training by the 6 minutes walking test and the quality of life, obesity and dietetics scale.

Conclusion

Aerobic exercise training of 8 weeks improves physical capacities and the psychosocial impact dimension of quality of life in men with Mets, without generating anthropometric modification.     

Adding strength to endurance training does not enhance aerobic capacity in cyclists

The molecular signaling of mitochondrial biogenesis is enhanced when resistance exercise is added to a bout of endurance exercise. The purpose of the present study was to examine if this mode of concurrent training translates into increased mitochondrial content and improved endurance performance. Moderately trained cyclists performed 8 weeks (two sessions per week) of endurance training only (E, n = 10; 60‐min cycling) or endurance training followed by strength training (ES, n = 9; 60‐min cycling + leg press). Muscle biopsies were obtained before and after the training period and analyzed for enzyme activities and protein content. Only the ES group increased in leg strength (+19%, P < 0.01), sprint peak power (+5%, P < 0.05), and short‐term endurance (+9%, P < 0.01). In contrast, only the E group increased in muscle citrate synthase activity (+11%, P = 0.06), lactate threshold intensity (+3%, P < 0.05), and long‐term endurance performance (+4%, P < 0.05). Content of mitochondrial proteins and cycling economy was not affected by training. Contrary to our hypothesis, the results demonstrate that concurrent training does not enhance muscle aerobic capacity and endurance performance in cyclists.     

Effect of exercise intervention on thigh muscle volume and anatomical cross‐sectional areas—Quantitative assessment using MRI

The objective of this study was to evaluate the location‐specific magnitudes of an exercise intervention on thigh muscle volume and anatomical cross‐sectional area, using MRI. Forty one untrained women participated in strength, endurance, or autogenic training for 12 weeks. Axial MR images of the thigh were acquired before and after the intervention, using a T1‐weighted turbo‐spin‐echo sequence (10 mm sections, 0.78 mm in‐plane resolution). The extensor, flexor, adductor, and sartorius muscles were segmented between the femoral neck and the rectus femoris tendon. Muscle volumes were determined, and anatomical cross‐sectional areas were derived from 3D reconstructions at 10% (proximal‐to‐distal) intervals. With strength training, the volume of the extensors (+3.1%), flexors (+3.5%), and adductors (+3.9%) increased significantly (P < 0.05) between baseline and follow‐up, and with endurance training, the volume of the extensor (+3.7%) and sartorius (+5.1%) increased significantly (P < 0.05). No relevant or statistically significant change was observed with autogenic training. The greatest standardized response means were observed for the anatomical cross‐sectional area in the proximal aspect (10–30%) of the thigh and generally exceeded those for muscle volumes. The study shows that MRI can be used to monitor location‐specific effects of exercise intervention on muscle cross‐sectional areas, with the proximal aspect of the thigh muscles being most responsive. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Strength training improves 5‐min all‐out performance following 185 min of cycling

To investigate the effects of heavy strength training on the mean power output in a 5‐min all‐out trial following 185 min of submaximal cycling at 44% of maximal aerobic power output in well‐trained cyclists. Twenty well‐trained cyclists were assigned to either usual endurance training combined with heavy strength training [E+S; n=11 (♂=11)] or to usual endurance training only [E; n=9 (♂=7, ♀=2)]. The strength training performed by E+S consisted of four lower body exercises [3 × 4–10 repetition maximum (RM)], which were performed twice a week for 12 weeks. E+S increased 1 RM in half‐squat (P≤0.001), while no change occurred in E. E+S led to greater reductions than E in oxygen consumption, heart rate, blood lactate concentration, and rate of perceived exertion (P<0.05) during the last hour of the prolonged cycling. Further, E+S increased the mean power output during the 5‐min all‐out trial (from 371 ± 9 to 400 ± 13 W, P<0.05), while no change occurred in E. In conclusion, adding strength training to usual endurance training improves leg strength and 5‐min all‐out performance following 185 min of cycling in well‐trained cyclists.     

Serum and plasma hormonal concentrations are sensitive to periods of intensity and volume of soccer training

Objectives

To investigate the effects of a 12-week training program on the hormonal concentrations and physiological performances of soccer players.

Equipment and methods

Eighteen subjects were evaluated at the beginning (T1), in the middle (T2) and at the end (T3) of the season. They had their blood collected for the analysis of cortisol, testosterone, testosterone/cortisol ratio, epinephrine and norepinephrine. The lactic and alactic anaerobic parameters and the anaerobic threshold were used as measures of physiological performance.

Results

While cortisol levels were higher in T2 and T3 compared to T1 (P ≤ 0.05), the testosterone values and the testosterone/cortisol ratios were significantly lower in T2 and T3 compared to T1 (P ≤ 0.05). Norepinephrine concentrations increased from T1 to T2 and T3 (P ≤ 0.05). In addition, while the alactic anaerobic performance parameters decreased significantly in T2 and T3 compared to T1 (P ≤ 0.05), the anaerobic threshold increased in T2 and T3 in comparison with T1 (P ≤ 0.05). In summary, we verified that NE levels might be used as sensitive markers for variations of volume and intensity of training. In addition, the changes in the levels of the selected hormones measured in the current study were not associated to negative responses of the physiological performances.     

Influence de l''hydratation sur la sécrétion d''hormone de croissance induite par l''exerciceHydration influence on exercise-induced growth hormone secretion

Aim – Study was then to investigate hydration influence on exercise-induced GHh secretion.Methods and results – Seven healthy men underwent a submaximal rectangular cycling exercise for 30 minutes to 150 watts during two sessions. A first one without any water intake and a second one with ingestion of spring water corresponding to the volume of water lost during the first session. Plasma volume decrease was significantly higher during the first session (p < 0.05). Total GH secretion was significantly lower during this session (p < 0.05).Conclusion – A moderate dehydration decreases exercise-induced GH response. Thus, hypovolemia may exert a negative feed back on GH secretion, during exercise.     

Effet d'un entraînement en endurance sur les concentrations de l'IGF-1 plasmatique chez le rat

Introduction

The aim of this study was to determine the effects of endurance training on IGF-1, corticosterone and insulin levels in male sedentary and trained rats.

Facts

IGF-1 concentrations decrease after training (p < 0.05), those of corticosterone increase (p < 0.01) whereas insulin levels remain stable.

Conclusion

A short period of endurance training leads to catabolic state with a decrease in IGF-1 concentrations and increase in corticosterone levels.     

Heart rate variability in prediction of individual adaptation to endurance training in recreational endurance runners

The aim of this study was to investigate whether nocturnal heart rate variability (HRV) can be used to predict changes in endurance performance during 28 weeks of endurance training. The training was divided into 14 weeks of basic training (BTP) and 14 weeks of intensive training periods (ITP). Endurance performance characteristics, nocturnal HRV, and serum hormone concentrations were measured before and after both training periods in 28 recreational endurance runners. During the study peak treadmill running speed (V_peak) improved by 7.5±4.5%. No changes were observed in HRV indices after BTP, but after ITP, these indices increased significantly (HFP: 1.9%, P=0.026; TP: 1.7%, P=0.007). Significant correlations were observed between the change of V_peak and HRV indices (TP: r=0.75, P<0.001; HFP: r=0.71, P<0.001; LFP: r=0.69, P=0.01) at baseline during ITP. In order to lead to significant changes in HRV among recreational endurance runners, it seems that moderate‐ and high‐intensity training are needed. This study showed that recreational endurance runners with a high HRV at baseline improved their endurance running performance after ITP more than runners with low baseline HRV.     

Influence of training load on upper respiratory tract infection incidence and antigen‐stimulated cytokine production

This study examined the effect of training load on upper respiratory tract infection (URTI) incidence in men and women engaged in endurance‐based physical activity during winter and sought to establish if there are training‐associated differences in immune function related to patterns of illness. Seventy‐five individuals provided resting blood and saliva samples for determination of markers of systemic immunity. Weekly training and illness logs were kept for the following 4 months. Comparisons were made between subjects (n = 25) who reported that they exercised 3–6 h/week (LOW), 7–10 h/week (MED) or ≥ 11 h/week (HIGH). The HIGH and MED groups had more URTI episodes than the LOW group (2.4 ± 2.8 and 2.6 ± 2.2 vs 1.0 ± 1.6, respectively: P < 0.05). The HIGH group had approximately threefold higher interleukin (IL)‐2, IL‐4 and IL‐10 production (all P < 0.05) by antigen‐stimulated whole blood culture than the LOW group and the MED group had twofold higher IL‐10 production than the LOW group (P < 0.05). Other immune variables were not influenced by training load. It is concluded that high levels of physical activity are associated with increased risk of URTI and this may be related to an elevated anti‐inflammatory cytokine response to antigen challenge.     

Intérêt du questionnaire de surentraînement de la Société française de médecine du sport lors d’un suivi de sportifsOvertraining questionnaire of Société française de médecine du sport for a continuous observation in a sport population

Aim. – Verify the sensibility of a standardised overtraining questionnaire during a weekly observation in a sport population.Methods and results. – The experiment was carried out in 12 athletes, 20–23 years old, students at the University in Licence STAPS, with a standardised overtraining questionnaire given every week during 8 weeks. Results were analysed individually and for the total population. Those showed that overtraining questionnaire could allow individualised training programs, and could provide some pertinent information on sleep quality and physical condition for each athlete. For the coach, the overtraining questionnaire permits to identify some fatigue state, consecutively to training variations. On the total population, the analysis of overtraining questionnaire showed some items more reliable than other.Conclusion. – This questionnaire was very interesting for coaches, allowing a good individualisation of the training program. Nevertheless, this questionnaire presents intricate statistical analysis when given at high frequency.     

A new model of short acceleration‐based training improves exercise performance in old mice

In order to identify a more appealing exercise strategy for the elderly, we studied a mouse model to determine whether a less time‐consuming training program would improve exercise performance, enzyme activities, mitochondrial respiration, and metabolomic parameters. We compared the effects of short‐session (acceleration‐based) training with those of long‐session endurance training in 23‐month‐old mice. The short‐session training consisted of five acceleration‐based treadmill running sessions over 2 weeks (the acceleration group), whereas the endurance training consisted of five‐one‐hour treadmill sessions per week for 4 weeks (the endurance group). A control group of mice was also studied. In the acceleration group, the post‐training maximum running speed and time to exhaustion were significantly improved, relative to pretraining values (+8% for speed, P<.05; +10% for time to exhaustion, P<.01). The post‐training maximum running speed was higher in the acceleration group than in the endurance group (by 23%; P<.001) and in the control group (by 15%; P<.05). In skeletal muscle samples, the enzymatic activities of citrate synthase, lactate dehydrogenase, and creatine kinase were significantly higher in the acceleration group than in the endurance group. Furthermore, mitochondrial respiratory activity in the gastrocnemius was higher in the acceleration group than in the control group. A metabolomic urine analysis revealed a higher mean taurine concentration and a lower mean branched amino acid concentration in the acceleration group. In old mice, acceleration‐based training appears to be an efficient way of increasing performance by improving both aerobic and anaerobic metabolism, and possibly by enhancing antioxidant defenses and maintaining muscle protein balance.     

Progenitor cell mobilization after exercise is related to systemic levels of G‐CSF and muscle damage

Different types of exercise are characterized by the ability to induce specific physiological stimuli that might be able to induce the mobilization of progenitor cells. The aim of the current study was to investigate the mobilization of hematopoietic progenitor cells (HPCs) and endothelial progenitor cells (EPCs) in response to endurance, resistance, and eccentric endurance exercise and their relation to markers of muscle damage and inflammation. Healthy male subjects performed acute bouts of either endurance exercise, resistance exercise, or eccentric endurance exercise. Numbers of progenitor cells and several markers of muscle damage and inflammation were determined. Although the endurance exercise was followed by an immediate and short increase of both HPCs and EPCs, the eccentric exercise evoked a long lasting increase up to 24 h for HPCs and 48 h for EPCs (P < 0.05). After resistance exercise, an increase of HPCs was only found 3 h after exercise (P < 0.05). A correlation was found between mobilized progenitor cells and systemic levels of granulocyte colony‐stimulating factor (G‐CSF) levels (r = 0.54 and r = 0.51, P < 0.05) as well as for HPCs and creatine kinase levels (r = 0.57, P < 0.05). These results suggest that mobilization of progenitor cells is related to the type of exercise and possibly mediated by G‐CSF and muscle damage.     

Neuromuscular and inflammatory responses to handball small‐sided games: the effects of physical contact

The aim of this study was to investigate the influence of physical contact on neuromuscular impairments and inflammatory response during handball small‐sided games. Using a counterbalanced design, 12 elite male junior handball players were divided into two groups: contact (C‐SSG) and no‐contact (NC‐SSG), performing both contact and no‐contact small‐sided games, in reverse order on two training sessions separated by 5 days. The methodology and rules were identical for the two SSG regimens, with the only difference being the inclusion or prohibition of upper body use for physical contacts. Upper and lower body neuromuscular performances and blood concentrations of inflammatory cytokine IL‐6 were assessed before and immediately after the games. During small‐sided games, video analysis was used to establish the physical contact counts. Significant differences were found in most upper and lower limbs muscles kinetic variables and in the physical contact events (all P < 0.001) following the two training regimens. There was an increase in IL‐6 after C‐SSG and no changes following NC‐SSG (P < 0.05 and P = 0.12, respectively). Moreover, a strong correlation was found between the number of physical contacts and IL‐6 responses (r = 0.971, P < 0.001) in C‐SSG. This study indicates that an inflammatory response and large upper and lower body neuromuscular impairments result from physical contact in elite handball players. These outcomes outline the specific physiological profile of C‐SSG that, in turn, might be used by practitioners and coaches as a practical approach to strategically select exercises in athlete's overall training program.     

Muscular adaptations after two different volumes of blood flow‐restricted training

This study aimed to gain an insight into the adaptations of muscle strength and skeletal muscle thickness after two different volumes of blood flow restriction training (BFRT), and compare them with high‐intensity training. The sample was divided into four groups: low‐volume, low‐intensity BFRT (BFRT LV); high‐volume, low‐intensity BFRT (BFRT HV); traditional high‐intensity resistance training (HIT); and a control group, which maintained their routine activities (CON). Leg extension one repetition maximum (1RM), isokinetic peak knee extension, and flexion torques at 60°/s and 180°/s as well as muscle thickness of the rectus femoris (RF) and vastus lateralis (VL) were assessed at baseline and after 5 weeks of training BFRT LV (7.03%, P < 0.05), BFRT HV (6.24%, P < 0.05) and HIT (18.86%, P < 0.001) groups increased 1RM performance, while no changes were observed in the CON group. Muscle thickness of the RF and VL was increased irrespective of the training group (7.5%, P < 0.001; and 9.9%, P < 0.001, respectively). We conclude that doubling the exercise volume with BFRT causes no further benefit with muscular size or strength. Although similar increases in muscle thickness were observed between training groups, HIT increased 1RM performance to a greater extent compared to either volume of BFRT.     

Block periodization of strength and endurance training is superior to traditional periodization in ice hockey players

Team sports like ice hockey require high levels of performance in numerous physical characteristics such as strength, power, and endurance. As such, training is associated with a potential interference effect. The present study randomized well‐trained ice hockey players into a block periodization group (BP; n = 8), focusing on the development of either strength and power or endurance on a weekly, undulating basis, and a traditional group (TRAD; n = 8), performing a mixed training model, with simultaneous focus of strength, power, and endurance training every week. During the 6‐week intervention, the two groups performed equal volumes and intensities of both strength, power, and endurance training. BP led to larger improvements than TRAD in knee extension peak torque at 180° s^?1 (6.6 ± 8.7 vs ?4.2% ± 6.3%, respectively; P < 0.05) and maximal oxygen uptake (5.1 ± 3.3 vs 1.1% ± 3.5%, respectively; P < 0.05). There was also a trend toward larger improvements in BP than TRAD in peak torque in knee extension at 60° s^?1 (2.1 ± 2.5 vs ?0.1% ± 2.5%, respectively; P < 0.1, effect size = 0.83) and mean power output during a 30‐s cycling sprint (4.1 ± 2.5 vs ?0.3% ± 5.9%, respectively; P < 0.1, effect size = 0.89). Overall, BP exhibited a moderate to large effect size for all these variables compared to TRAD. The present study suggests that block periodization of strength and endurance training induces superior adaptations in both strength and endurance capacities in well‐trained ice hockey players compared to traditional mixed organization, despite similar training volume and intensity.