Hugues Portier

Intense endurance training on heart rate and blood pressure variability in runners.

UNLABELLED Physical training with incomplete recovery times can produce significant fatigue. A study of cardiovascular responses showed that there is a sympathetic and a parasympathetic form of fatigue. PURPOSE The purpose of this experimentation was to measure the effects of intense endurance training on autonomic balance through a spectral analysis study of the heart rate (HR) and systolic blood pressure (SBP). METHODS Eight elite runners were tested twice: after a relative rest period (RRP) of 3 wk and after an 12-wk intense training period (ITP) for endurance. At the end of each phase, the subjects were tested by means of a VO2max test and a tilt-table test. RESULTS The resting heart rate (HR) variability was lower (P < 0.001) in the intensive training phase. Likewise, there were differences in the low-frequency (0.04-0.150 Hz; LF) and high-frequency (0.150-0.500 Hz; HF) components and the LF/HF ratio of the HR spectral analysis. The LF spectral power was significantly lower in the supine position (P < 0.05) during ITP. Upright tilting was accompanied by a 22.6% reduction in HF values during the rest period, whereas in ITP the HF spectral power rose by 31.2% (P < 0.01) during tilt, characterizing a greater parasympathetic system control. Sympathetic control represented by the LF/HF ratio regressed markedly (P < 0.01) in response to the tilt test in ITP. CONCLUSIONS The spectral analysis of SBP in the high frequencies shows that the changes in cardiac parameters are coupled with a decrease in sympathetic vasomotor control (-18%) and a reduction in diastolic pressure (-3.2%) in the response to the tilt test at the end of ITP. Spectral analysis could be a means of demonstrating impairment of autonomic balance for the purpose of detecting a state of fatigue that could result in overtraining.

Effects of acute salbutamol intake during supramaximal exercise in women.

Objective: To study the effects of an acute therapeutic oral intake of β2 agonist on performance and substrate response during supramaximal exercise in women. Methods: 12 healthy moderately trained female volunteers performed a Wingate test after ingestion of placebo (Pla) and salbutamol (Sal; 4 mg) according to a double-blind randomised crossover study. Blood samples were collected at rest, at the end of exercise and after 5 (r5), 10 (r10) and 15 (r15) min of passive recovery for adrenocorticotropic hormone (ACTH), growth hormone (GH), insulin, blood glucose and lactate measurements. Results: Peak power (PP) and mean power (MP) significantly increased whereas time to peak power was significantly shorter with Sal than with Pla (p<0.05). No change was observed in the fatigue index. ACTH was not significantly modified but r15 growth hormone significantly decreased (p<0.05) after the intake of Sal. Both blood INS and blood glucose were significantly increased by the intake of Sal during all the experiments (p<0.01). Blood lactate was significantly increased by the intake of Sal compared with that of Pla (p<0.05) after 10 and 15 min of passive recovery. Conclusion: From these data, acute therapeutic oral intake of Sal seems to induce, irrespective of the subjects’ gender, an improvement in performance during a supramaximal exercise—that is, increase in PP and MP. Further studies are necessary to clarify whether the mechanisms involved in the response to intake of Sal are linked to central and/or peripheral pathways.

Short-term glucocorticoid intake combined with intense training on performance and hormonal responses

Objective: To investigate the effects of short-term prednisolone ingestion combined with intense training on exercise performance, hormonal (adrenocorticotrophic hormone (ACTH), prolactin, luteinising hormone (LH), growth hormone (GH), thyroid-stimulating hormone (TSH), dehydroepiandrosterone (DHEA), testosterone, insulin) and metabolic parameters (blood glucose, lactate, bicarbonate, pH). Methods: Eight male recreational athletes completed four cycling trials at 70–75% peak O2 consumption until exhaustion just before (1) and after (2) either oral placebo or prednisolone (60 mg/day for 1 week) treatment coupled with standardised physical training (2 hours/day), according to a double-blind and randomised protocol. Blood samples were collected at rest, during exercise and passive recovery for the hormonal and metabolic determinations. Results: Time of cycling was not significantly changed after placebo but significantly increased (p<0.05) after prednisolone administration (50.4 (6.2) min for placebo 1, 64.0 (9.1) min for placebo 2, 56.1 (9.1) min for prednisolone 1 and 107.0 (20.7) min for prednisolone 2). There was no significant difference in any measured parameters after the week of training with placebo but a decrease in ACTH, DHEA, PRL, GH, TSH and testosterone was seen with prednisolone treatment during the experiment (p<0.05). No significant change in basal, exercise or recovery LH, insulin, lactate, pH or bicarbonate was found between the two treatment, but blood glucose was significantly higher under prednisolone (p<0.05) at all time points. Conclusion: Short-term glucocorticoid administration induced a marked improvement in endurance performance. Further studies are needed to determine whether these results obtained in recreational male athletes maintaining a rigorous training schedule are gender-dependent and applicable to elite athletes.

Short-term salbutamol ingestion and supramaximal exercise in healthy women

Objective: To test the hypothesis that chronic salbutamol intake improves performance during supramaximal exercise and to estimate the effects of this treatment on body composition, bone mass, and metabolic indices in healthy women. Methods: Fourteen female volunteers (seven sedentary and seven recreationally trained) performed a 30 second Wingate test with and without salbutamol ingestion (12 mg/day for four weeks) in a random, double blind, crossover design. Blood samples were collected at rest, at the end of the test, and during passive recovery for lactate measurement. Body composition and bone mass were determined by dual energy x ray absorptiometry. Results: Peak power appeared significantly earlier and was significantly (p<0.05) increased after salbutamol intake in all subjects. There was no difference in total work performed and fatigue indices with salbutamol compared with placebo. No significant alterations in lean or fat body mass and bone variables were observed with salbutamol treatment in either trained or untrained subjects during the trial. In contrast, blood lactate was significantly (p<0.05) increased during the recovery period after salbutamol ingestion compared with placebo. Conclusion: As in men, chronic administration of therapeutic concentrations of salbutamol did not induce an anabolic effect in women but increased maximal anaerobic power. Further studies are necessary to clarify the mechanisms involved.

Effects of acute prednisolone administration on exercise endurance and metabolism

Objective: To examine whether acute glucocorticoid (GC) intake alters performance and selected hormonal and metabolic variables during submaximal exercise. Methods: In total, 14 recreational male athletes completed two cycling trials at 70–75% maximum O2 uptake starting 3 h after an ingestion of either a lactose placebo or oral GC (20 mg of prednisolone) and continuing until exhaustion, according to a double-blind randomised protocol. Blood samples were collected at rest, after 10, 20, 30 minutes, and at exhaustion and recovery for measurement of growth hormone (GH), adrenocorticotropic hormone (ACTH), dehydroepiandrosterone (DHEA), prolactin, insulin, blood glucose, lactate and interleukin (IL)-6 determination. Results: Cycling duration was not significantly changed after GC or placebo administration (55.9 (5.2) v 48.8 (2.9) minutes, respectively). A decrease in ACTH and DHEA (p<0.01) was observed with GC during all of the experiments and in IL-6 after exhaustion (p<0.05). No change in basal, exercise or recovery GH, prolactin, insulin or lactate was found between the two treatments but blood glucose was significantly higher with GC (p<0.05) at any time point. Conclusion: From these data, acute systemic GC administration does seem to alter some metabolic markers but did not influence performance during submaximal exercise.

Effect of the alcohol consumption on osteocyte cell processes: a molecular imaging study

We have previously shown microarchitectural tissue changes with cellular modifications in osteocytes following high chronic alcohol dose. The aim of this study was to assess the dose effect of alcohol consumption on the cytoskeleton activity, the cellular lipid content and modulation of differentiation and apoptosis in osteocyte. Male Wistar rats were divided into three groups: Control (C), Alcohol 25% v/v (A25) or Alcohol 35% v/v (A35) for 17 weeks. Bone mineral density (BMD) was assessed by DXA, osteocyte empty lacunae, lacunae surface, bone marrow fat with bright field microscopy. Osteocyte lipid content was analysed with transmission electron microscopy (TEM) and epifluorescence microscopy. Osteocyte apoptosis was analysed with immunolabelling and TEM. Osteocyte differentiation and cytoskeleton activity were analysed with immunolabelling and real time quantitative PCR. At the end of the protocol, BMD was lower in A25 and A35 compared with C, while the bone marrow lipid content was increased in these groups. More empty osteocyte lacunae and osteocyte containing lipid droplets in A35 were found compared with C and A25. Cleaved caspase‐3 staining and chromatin condensation were increased in A25 and A35 versus C. Cleaved caspase‐3 was increased in A35 versus A25. CD44 and phosphopaxillin stainings were higher in A35 compared with C and A25. Paxillin mRNA expression was higher in A35 versus A25 and C and sclerostin mRNA expression was higher in A35 versus C. We only observed a dose effect of alcohol consumption on cleaved caspase‐3 osteocyte immunostaining levels and on the number of lipid droplets in the bone marrow.

Does running strengthen bone

Bone is a living tissue needing mechanical stress to maintain strength. Traditional endurance exercises offer only modest effects on bone. Walking and running produce low impact but lead to bone fatigue. This article is specifically addressed to therapists and explains the mechanisms involved for the effects of exercise on bone. Intermittent exercise limits bone fatigue, and downhill exercises increase ground impact forces and involve eccentric muscle contractions, which are particularly osteogenic.

Quick benefits of interval training versus continuous training on bone: a dual-energy X-ray absorptiometry comparative study

To delay age‐related bone loss, physical activity is recommended during growth. However, it is unknown whether interval training is more efficient than continuous training to increase bone mass both quickly and to a greater extent. The aim of this study was to compare the effects of a 10‐week interval training regime with a 14‐week continuous training regime on bone mineral density (BMD). Forty‐four male Wistar rats (8 weeks old) were separated into four groups: control for 10 weeks (C10), control for 14 weeks (C14), moderate interval training for 10 weeks (IT) and moderate continuous training for 14 weeks (CT). Rats were exercised 1 h/day, 5 day/week. Body composition and BMD of the whole body and femur respectively were assessed by dual‐energy X‐ray absorptiometry at baseline and after training to determine raw gain and weight‐normalized BMD gain. Both trained groups had lower weight and fat mass gain when compared to controls. Both trained groups gained more BMD compared to controls when normalized to body weight. Using a 30% shorter training period, the IT group showed more than 20% higher whole body and femur BMD gains compared to the CT. Our data suggest that moderate IT was able to produce faster bone adaptations than moderate CT.