A laboratory running test: metabolic responses of sprint and endurance trained athletes.

A laboratory-based sprint running test has been devised to examine the performance characteristics and metabolic responses of an individual to 30 seconds of maximal exercise. A non-motorised treadmill was used so that the individual was able to sprint at his own chosen speed and also to vary his speed as fatigue occurred. The treadmill was instrumented so that the chosen speeds as well as the equivalent distance travelled could be monitored by micro-computer throughout the test. The test-retest reliability of the procedure was investigated with 14 recreational runners who performed the test on different days. A good correlation (r = 0.93) was found between the values obtained for peak running speeds on the two occasions. In an attempt to establish whether or not this test could be used to identify the differences in the performance characteristics of highly trained individuals, the responses to the test of eleven sprint trained and eleven endurance trained athletes were examined. The sprint trained athletes covered a greater distance (162.2 +/- 5.95 m vis 153.51 +/- 12.32 m; p less than 0.01) and had higher blood lactate concentrations (16.52 +/- 1.23 mM vis 12.98 +/- 1.77 mM; p less than 0.01) than the endurance trained athletes. Therefore this laboratory sprint running test offers an additional way of investigating human responses to brief periods of high intensity exercise.     

Acute antioxidant supplementation improves endurance performance in trained athletes

This study examined the acute effects of a single dose of an antioxidant (AO; Lactaway? containing pycnogenol) on time to fatigue (TTF). Nine trained cyclists [mean ± SD age 35 ± 10 yrs; body mass 71.6 ± 10.2 kg; VO2 peak 63 ± 11 ml/kg/min] performed on two separate occasions a continuous protocol of 5 min at 50% of peak power output (PPO), 8 min at 70% of PPO, and then cycled to fatigue at 95% PPO. Four hours prior to the exercise protocol, the subjects consumed the supplement or a placebo (counterbalanced, double blind protocol). Cyclists, on average, rode for 80 s more in the Lactaway trial than they did in the placebo trial. There was considerable evidence (chances ≥94.5%) for substantial positive treatment effects for TTF and the other performance-related variables (excluding [BLa] at 95% PPO). Other studies are necessary to confirm these results and identify the mechanisms underlying the observed effects.     

Performance trends in Paralympic athletes in sprint,middle-distance and endurance events

Sport Sciences for Health - In recent decades the participation in Paralympic sports has grown exponentially, with an increasing number of countries and athletes attending to these events. However,...     

Bone mineral content of cyclically menstruating female resistance and endurance trained athletes

The bone mineral content (BMC) at four sites on the axial and appendicular skeleton was compared among four groups of young adult (age = 17-38 yr) cyclically menstruating athletes (N = 40) who regularly performed either weightlifting resistance exercise (body builders) or nonresistance endurance exercise (runners, swimmers) and an inactive group of females (N = 18) of about equal age. Forearm BMC was measured using single photon absorptiometry at proximal (shaft) and distal sites on the radius. Dual photon absorptiometry was used to measure BMC at the lumbar vertebrae (L2-4) and femur at the femoral neck, Ward's triangle, and greater trochanter. Fat-free body mass (FFBM) was estimated from densitometry. Body builders had greater BMC than swimmers, collegiate runners, recreational runners, and controls. Mean differences in BMC among runners, swimmers, and controls were not significant (P less than or equal to 0.05). FFBM was correlated significantly with BMC (r = 0.35-0.56) at each site in the combined group of athletes (N = 39), whereas total body weight and BMC were correlated significantly at the distal radius site (r = 0.38) only. The results suggest that weight training may provide a better stimulus for increasing BMC than run and swim training.     

Specificity of endurance, sprint and strength training on physical performance capacity in young athletes

Three prebubescent athlete groups of endurance runners (E; n = 4), sprinters (S; n = 4) and weightlifters (WL; n = 4) and one control group (C; n = 6) as well as one junior but postpubescent weightlifter group (JWL; n = 6) volunteered as subjects in order to investigate specific effects of endurance, sprint and strength training on physical performance capacity during a 1 year follow-up period. The prepubescent E-group had higher (p less than 0.05) VO2 max (66.5 +/- 2.9 ml x kg1 x min-1) already at the beginning of the study than the other three groups. The prepubescent WL-group demonstrated greater (p less than 0.05) maximal muscular strength than the E-group and the WL-group increased its strength greatly by 21.4% (p less than 0.05) during the follow-up. No significant differences were observed in physical performance capacity between the prepubescent WL- and S-groups. Both groups demonstrated a slightly (ns.) better force-time curve recorded from the leg extensor muscles than the E-group and significant (p less than 0.05) increases occurred in these two groups in dynamic explosive performance during the follow-up. The postpubescent JWL-group demonstrated much greater (p less than 0.001) muscular mass and maximal strength than the prepubescent groups. No significant changes occurred in explosive types of performances in these athletes but significant (p less than 0.05) increase took place in the maximal neural activation and strength of the leg extensor muscles during the 1 year.(ABSTRACT TRUNCATED AT 250 WORDS)     

The response of trained athletes to six weeks of endurance training in hypoxia or normoxia

This study was performed to investigate the effect of training under simulated hypoxic conditions. Hypoxia training was integrated into the normal training schedule of 12 endurance trained cyclists. Athletes were randomly assigned to two groups and performed three additional training bouts per week for six weeks on a bicycle ergometer. One group (HG) trained at the anaerobic threshold under hypoxic conditions (corresponding to an altitude of 3200 m) while the control group (NG) trained at the same relative intensity at 560 m. Preceding and following the six training weeks, performance tests were performed under normoxic and hypoxic conditions. Normoxic and hypoxic .VO2max, maximal power output as well as hypoxic work-capacity were not improved after the training period. Testing under hypoxic conditions revealed a significant increase in oxygen saturation (SpO 2, from 67.1 +/- 2.3 % to 70.0 +/- 1.7 %) and in maximal blood lactate concentration (from 7.0 to 9.1 mM) in HG only. Ferritin levels were decreased from 67.4 +/- 16.3 to 42.2 +/- 9.5 microg/l (p < 0.05) in the HG and from 54.3 +/- 6.9 to 31.4+/- 8.0 microg/l (p = 0.17) in the NG. Reticulocytes were significantly increased in both groups by a factor of two. In conclusion, the integration of six weeks of high intensity endurance training did not lead to improved performance in endurance trained athletes whether this training was carried out in hypoxic or normoxic conditions.     

Adaptation to a ketogenic diet modulates adaptive and mucosal immune markers in trained male endurance athletes

This study examined the effect of short‐term adaptation to a ketogenic diet (KD) on resting and post‐exercise immune markers. Using a randomized, repeated‐measures, crossover design, eight trained, male, endurance athletes ingested a 31‐day low carbohydrate (CHO), KD (energy intake: 4% CHO; 78% fat) or their habitual diet (HD) (energy intake: 43% CHO; 38% fat). On days 0 and 31, participants ran to exhaustion at 70% VO_2max. A high‐CHO (2 g·kg^?1) meal was ingested prior to the pre‐HD, post‐HD, and pre‐KD trials, with CHO (~55 g·h^?1) ingested during exercise, whereas a low‐CHO (<10 g) meal was ingested prior to the post‐KD trial, with fat ingested during exercise. Blood and saliva samples were collected at pre‐exercise, exhaustion, and 1 hour post‐exhaustion. T‐cell‐related cytokine gene expression within peripheral blood mononuclear cells (PBMCs) and whole‐blood inflammatory cytokine production were determined using 24‐hour multi‐antigen‐stimulated whole‐blood cultures. Multi‐antigen‐stimulated PBMC IFN‐γ mRNA expression and the IFN‐γ/IL‐4 mRNA expression ratio were higher at exhaustion in the post‐KD compared with pre‐KD trial (P = 0.003 and P = 0.004); however, IL‐4 and IL‐10 mRNA expression were unaltered (P > 0.05). Multi‐antigen‐stimulated whole‐blood IL‐10 production was higher in the post‐KD compared with pre‐KD trial (P = 0.028), whereas IL‐1β, IL‐2, IL‐8, and IFN‐γ production was lower in the post‐HD compared with pre‐HD trial (P < 0.01). Salivary immunoglobulin A (SIgA) secretion rate was higher in the post‐KD compared with pre‐KD trial (P < 0.001). In conclusion, short‐term adaptation to a KD in endurance athletes may alter the pro‐ and anti‐inflammatory immune cell cytokine response to a multi‐antigen in vitro and SIgA secretion rate.     

Montelukast does not affect exercise performance at subfreezing temperature in highly trained non-asthmatic endurance athletes

Anti-leukotriene therapy represents a new principle in asthma treatment. As elite athletes can have asthma, this double-blind, placebo-controlled, randomised cross-over study investigated the effect of 10 mg oral montelukast, a specific and potent cysteinyl leukotriene receptor antagonist, on physiological responses to submaximal and maximal aerobic exercise at -15 degrees C in 14 non-asthmatic highly trained endurance male athletes (maximal oxygen uptake [VO2 max] > 70 ml x kg(-1) x min(-1)). Heart rate, capillary blood lactate, minute ventilation with tidal volume and breathing frequency, respiratory exchange ratio and oxygen uptake were measured during the warm-up run of 10 min at 50%, runs of 10 min at 90% and 5 min at 80% VO2max, and a timed run to exhaustion. Spirometry was performed at baseline, at four hours after tablet ingestion, after warm-up and exercise at 80% VO2max, and in the post exercise period. Compared to placebo, montelukast did not increase baseline FEV1, have a beneficial effect on physiological performance variables, or increase the mean (SD) running time to exhaustion (montelukast: 332.3 [45.8] s, placebo: 340.1 [53.3] s, P = 0.22). These findings do not suggest the need for disallowing the use of this drug by asthmatic athletes.     

Pregnancy in endurance athletes

The purpose of the present study was to examine pregnancy and delivery among Finnish endurance athletes at the national top level. A questionnaire concerning first. pregnancy was sent to 30 Finnish endurance athletes who had been at national top level in cross-country skiing, running, speed-skating or orienteering. Data on labour were collected retrospectively through a questionnaire and from the diaries in the hospital concerned. The next primipara in the diaries formed a member of the control group. Twenty-three athletes (77%) had regular menstrual cycles, seven (23%) had irregularities, and four of them had received hormonal treatment for this. Seven athletes (23%) had experienced spontaneous abortion during the first trimester in previous pregnancy. Sixteen (53%) did not notice any change in their exercise performance, three (10%) subjectively felt themselves to be in a better physical condition, and seven (23%) felt themselves to be in a worse condition than before the pregnancy. Four did not respond on the question. After delivery, 18 athletes continued to compete, the median interval being 8.2 months (range 2–24 months). Two of them (11%) achieved a better condition than before the pregnancy, 11 (61%) reached the same level and five (28%) did not achieve the same performance level. There were no significant differences in labour parameters between the athletes and controls. Endurance training had no harmful side-effects on the pregnancies or deliveries of the athletes. The effect of pregnancy on exercise performance is individual.     

Sperm characteristics of endurance trained cyclists

The purpose of this study was to investigate the influence of cycling on sperm characteristics. Twenty subjects volunteered for the study, comprising 10 long distance competitive cyclists (median 25.5 y) and 10 sedentary controls (median 24.5 y). A questionnaire was used to obtain a history of training, health, nutrition and life style. Semen analysis consisted of a detailed evaluation of sperm characteristics that included semen volume, sperm count, viability, motility and morphology. Compared to controls, the cyclists had a significantly lower proportion of spermatozoa with normal morphology (medians: 41.5 % versus 19.5 %; p < 0.01) and a significantly higher proportion of morphologically abnormal tapered forms (medians: 4.5 % versus 22.5 %; p < 0.01). No significant difference in semen volume and sperm motility, viability and count was observed between the two groups. We concluded that endurance cycling appears to be associated with a significant alteration in sperm morphology.     

Physiological characteristics of sprint and endurance Masters runners.

Data were obtained from 13 sprint (age range 41-58) and 13 distance (age range 4-78) Masters track athletes. The mean VO2max value for the distance runners was 54.4 +/- 3 ml kg min compared with 47.2 +/- 2 ml kg min for the sprinters. The highest VO2max (71.0 ml kg min) was obtained on a 45-year-old distance runner while the lowest (27.3 ml kg min) was obtained on the oldest (78 years) distance runner. VO2max decreased by 34.5% from age 40 to 70 in the distance runner in spite of continued training that ranged from 40 to 120 miles/week. Maximum ventilation rates were 122.5 +/- 6.8 and 116.8 +/- 7.0 1 min for the sprint and distance runners, respectively. Percentage of body fat was 16.5 +/- 0.5 for the sprinters and 18.0 +/- 1.1 for the distance runners. Serum cholesterol values were 218.7 +/- 8.7 and 203.0 +/- 13.8 ml/dl, while triglyceride values were 101.5 +/- 8.2 and 84.1 +/- 9.3 mg/dl for the sprint and distance groups, respectively. These data indicate that, VO2max decreases significantly with aging despite the continuation of long distance training. Percent body fat and serum lipid levels were significantly lower in these athletes compared to those for sedentary adults, suggesting a protective effect against coronary heart disease. Only one subject had S-T segment depression during the exercise test.     

MRI及31P-MRS在脂质沉积性肌病中的诊断

目的:应用磁共振成像(MRI)及磷频谱(31P-MRS)评价脂质沉积性肌病(LSM)的影像表现,探讨其临床应用价值.方法:对经病理证实的6例LSM和17例健康对照者进行MRI及31P-MRS检查.结果:6例LSM患者大腿后组肌群和内侧肌群T1 WI及T2 WI上均表现为多发小斑点状高信号,T2 WI抑脂后信号减低;LSM组PCr(磷酸肌酸)、PCr/ATP(三磷酸腺苷)和磷酸化能力(PP)较对照组明显降低(P＜0.05),二磷酸腺苷(ADP)、Pi(无机磷)、Pi/ATP、Pi/PCr较对照组明显增高(P＜0.05),PH与对照组无明显差别(P=0.6395).结论:MRI联合31P-MRS检查有利于LSM的诊断、鉴别诊断.     

Evidence for an inadequate hyperventilation inducing arterial hypoxemia at submaximal exercise in all highly trained endurance athletes

PURPOSE: The majority of highly trained endurance athletes with a maximal oxygen uptake greater than 60 mL x min(-1) x kg(-1) develop exercise-induced hypoxemia (EIH). Yet some of them apparently do not. The pathophysiology of EIH seems to be multifactorial, and one explanatory hypothesis is a relative hypoventilation. Nevertheless, conflicting results have been reported concerning its contribution to EIH. The aim of this study was to compare the cardiorespiratory responses to maximal exercise of highly trained endurance athletes demonstrating the same aerobic capacity without EIH (N athletes) and with EIH (H athletes). METHODS: Ten N athletes and twelve H athletes performed an incremental exercise test. Measurements of arterial blood gases and cardiorespiratory parameters were performed at rest and during exercise. RESULTS: All athletes presented a significant decrease in PaO2 (P < 0.05) from rest up to 80% VO2max associated with an increase in PaCO2, both findings consistent with a relative hypoventilation. Then the H athletes, who had a greater training volume per week and a higher second ventilatory threshold than the N athletes (respectively, 17 +/- 1.1 vs 13.1 +/- 0.7 h x wk(-1); 91.8 +/- 1.7 vs 86.1 +/- 1.8% VO2max), presented a continuous PaO2 decrease up to VO2max. This was associated with a widening (Ai-a)DO2. CONCLUSION: This study showed that a relative hypoventilation, probably induced by a high level of endurance training, induced hypoxemia in all athletes. However, a nonventilatory mechanism, perhaps related to the volume of training, seemed to affect gas exchanges beyond the second ventilatory threshold in the H athletes, thereby enhancing EIH.     

Asymptomatic bradycardia amongst endurance athletes

It is established that an intensive training results in a lower average resting heart rate. Management of bradycardia in an athlete can be difficult given the underlying mechanisms are not clearly understood. The authors reviewed the different mechanisms described in the literature, including recent advances in physiology regarding remodeling of ion channels, which may partially explain bradycardia in athletes. Sinus bradycardia amongst athletes, especially endurance focused athletes, is common but difficult to apprehend. The underlying mechanisms are observably of multifactorial origin and likely incompletely elucidated by the current body of knowledge.     

Sodium bicarbonate improves sprint performance in endurance cycling

ObjectivesOral sodium bicarbonate intake (NaHCO₃) may improve performance in short maximal exercise by inducing metabolic alkalosis. However, it remains unknown whether NaHCO₃ also enhances all-out performance at the end of an endurance competition. Therefore, the present study investigated the effect of stacked NaHCO₃ loading on sprint performance following a 3-h simulated cycling race.DesignDouble-blind randomized placebo-controlled cross-over study.MethodsEleven trained male cyclists (22.3 (18.3–25.3) year; 73.0 (61.5–88) kg; VO₂max: 63.7 (57–72) ml kg^?1 min^?1) ingested either 300 mg kg^?1 body weight NaHCO₃ (BIC) or NaCl (PL). NaHCO₃ or NaCl was supplemented prior to (150 mg kg^?1) and during (150 mg kg^?1) a 3-h simulated cycling race with a 90-s all-out sprint (90S) at the end. Capillary blood samples were collected for determination of blood pH, lactate and HCO₃^? concentrations. Analysis of variance (lactate, pH, HCO₃^?) and paired t-test (power) were applied to compare variables across condition (and time).ResultsNaHCO₃ intake improved mean power during 90S by ～3% (541 ± 59 W vs. 524 ± 57 W in PL, p = 0.047, Cohen’s D = 0.28, medium). Peak blood lactate concentration and heart rate at the end of 90S were higher (p < 0.05) in BIC (16.2 ± 4.1 mmol l ¹, 184 ± 7 bpm) than in PL (12.4 ± 4.2 mmol l^?1, 181 ± 5 bpm). NaHCO₃ ingestion increased blood [HCO₃^?] (31.5 ± 1.3 vs. 24.4 ± 1.5 mmol l^?1 in PL, p < 0.001) and blood pH (7.50 ± 0.01 vs. 7.41 ± 0.03 in PL, p < 0.05) prior to 90S.ConclusionsNaHCO₃ supplementation prior and during endurance exercise improves short all-out exercise performance at the end of the event. Therefore, sodium bicarbonate intake can be applied as a strategy to increase success rate in endurance competitions.     

Exercise-induced hypoxaemia in highly trained athletes

Traditionally, the pulmonary system has not been considered the limiting factor in determining maximal oxygen uptake (VO2max) in healthy individuals since arterial oxygen-haemoglobin saturation is thought to remain high during intense exercise. However, there appears to be a major exception to this rule. Recent evidence suggests that arterial hypoxaemia results during heavy exercise in well trained individuals with a high VO2max. Further, the degree of arterial desaturation is inversely related to VO2max. This exercise-induced hypoxaemia does not appear to be due to hypoventilation although athletes who have limited hyperventilation seem to exhibit the lowest arterial oxygen-haemoglobin saturation. A significant venoarterial shunt has been ruled out as a primary cause of the hypoxaemia based on both experimental and theoretical considerations. Therefore, it appears that the exercise-induced hypoxaemia seen in highly trained athletes during heavy exercise is primarily due to diffusion limitations and ventillation-perfusion inequality. It is postulated that incomplete diffusion in the healthy lung may be due to a rapid red blood cell transit time through the pulmonary capillary. In summary, recent findings suggest that the limits of the human pulmonary system may be reached or even exceeded during intense exercise in some individuals. In light of these findings the role of the pulmonary system as a limiting factor during maximal exercise in the highly trained endurance athlete warrants further investigation.     

31P-MRS在正常骨骼肌运动中的研究现状及应用前景

1 MRS 基本原理 磁共振波谱(magnetic resonance spectroscopy,MRS)是利用核磁共振现象及其化学位移或自旋耦合作用,来测定特定原子核及其化合物的分子成分和含量的一种检测技术,亦是目前惟一对活体的组织代谢、生化环境等进行定量分析的方法,具有无创性[1]、可重复性以及发现代谢异常的敏感性等特点,能有机结合磁共振成像提供的多个体素的频谱信息和代谢物空间分布图像信息,将影像学研究深入到生物化学甚至基因水平,分单体素波谱和多体素波谱.     

The scientific basis for high-intensity interval training: optimising training programmes and maximising performance in highly trained endurance athletes.

While the physiological adaptations that occur following endurance training in previously sedentary and recreationally active individuals are relatively well understood, the adaptations to training in already highly trained endurance athletes remain unclear. While significant improvements in endurance performance and corresponding physiological markers are evident following submaximal endurance training in sedentary and recreationally active groups, an additional increase in submaximal training (i.e. volume) in highly trained individuals does not appear to further enhance either endurance performance or associated physiological variables [e.g. peak oxygen uptake (VO2peak), oxidative enzyme activity]. It seems that, for athletes who are already trained, improvements in endurance performance can be achieved only through high-intensity interval training (HIT). The limited research which has examined changes in muscle enzyme activity in highly trained athletes, following HIT, has revealed no change in oxidative or glycolytic enzyme activity, despite significant improvements in endurance performance (p < 0.05). Instead, an increase in skeletal muscle buffering capacity may be one mechanism responsible for an improvement in endurance performance. Changes in plasma volume, stroke volume, as well as muscle cation pumps, myoglobin, capillary density and fibre type characteristics have yet to be investigated in response to HIT with the highly trained athlete. Information relating to HIT programme optimisation in endurance athletes is also very sparse. Preliminary work using the velocity at which VO2max is achieved (V(max)) as the interval intensity, and fractions (50 to 75%) of the time to exhaustion at V(max) (T(max)) as the interval duration has been successful in eliciting improvements in performance in long-distance runners. However, V(max) and T(max) have not been used with cyclists. Instead, HIT programme optimisation research in cyclists has revealed that repeated supramaximal sprinting may be equally effective as more traditional HIT programmes for eliciting improvements in endurance performance. Further examination of the biochemical and physiological adaptations which accompany different HIT programmes, as well as investigation into the optimal HIT programme for eliciting performance enhancements in highly trained athletes is required.     

Between 21 and 34 years of age, aging alters the catecholamine responses to supramaximal exercise in endurance trained athletes.

The purpose of this study was to determine the effect of aging and training on the adrenaline (A) and noradrenaline (NA) responses during the Wingate-test in three age groups of subjects: 21 year old untrained subjects (21U), 21 year old endurance trained (21T) (national elite runners), 34 year old endurance trained (34T) (national elite runners). Performances during the test were judged using the usual parameters of peak power (Wmax) and mean power (W) expressed in absolute or relative values. A and NA responses were measured at rest (A0 and NA0) immediately at the end of the exercise (Amax and NAmax) and after 5 minutes recovery (A5 and NA5). Plasma maximal lactate (La(max)) was determined 3 minutes after the end of the exercise. Wmax, W and La(max) were always significantly lower in 34T compared to 21T and 21U. The catecholamine responses were similar in 21T and 21U. Inversely, a significantly lower value of Amax was observed in 34T (2.01 +/- 0.5 nmol x l(-1)) compared to 21U (3.62 +/- 0.3 nmol x l(-1)) associated with a significantly higher value of NA(max) in 34T versus 21T and 21U. Thus, the Amax/NA(max) ratio was found to be significantly lower in the older subjects versus both 21T and 21U. All these findings indicated that endurance training did not affect the sympathoadrenergic responses to a supramaximal exercise and suggested that only one decade may reduce the capacity of the medulla to secrete adrenaline and therefore the adrenal medulla responsiveness to the sympathetic nervous activity.