Simulated moderate altitude elevates serum erythropoietin but does not increase reticulocyte production in well-trained runners

The purpose of this study was to investigate whether the modest increases in serum erythropoietin (sEpo) experienced after brief sojourns at simulated altitude are sufficient to stimulate reticulocyte production. Six well-trained middle-distance runners (HIGH, mean maximum oxygen uptake, V˙O_2max = 70.2 ml · kg⁻¹ · min⁻¹) spent 8–11 h per night for 5 nights in a nitrogen house that simulated an altitude of 2650 m. Five squad members (CONTROL, mean V˙O_2max = 68.9 ml · kg⁻¹ · min⁻¹) undertook the same training, which was conducted under near-sea-level conditions (600 m altitude), and slept in dormitory-style accommodation also at 600 m altitude. For both groups, this 5-night protocol was undertaken on three occasions, with a 3-night interim between successive exposures. Venous blood samples were measured for sEpo after 1 and 5 nights of hypoxia on each occasion. The percentage of reticulocytes was measured, along with a range of reticulocyte parameters that are sensitive to changes in erythropoiesis. Mean serum erythropoietin levels increased significantly (P < 0.01) above baseline values [mean (SD) 7.9 (2.4) mU · ml⁻¹] in the HIGH group after the 1st night [11.8 (1.9) mU · ml⁻¹, 57%], and were also higher on the 5th night [10.7 (2.2) mU · ml⁻¹, 42%] compared with the CONTROL group, whose erythropoietin levels did not change. After athletes spent 3 nights at near sea level, the change in sEpo during subsequent hypoxic exposures was markedly attenuated (13% and −4% change during the second exposure; 26% and 14% change during the third exposure; 1st and 5th nights of each block, respectively). The increase in sEpo was insufficient to stimulate reticulocyte production at any time point. We conclude that when daily training loads are controlled, the modest increases in sEpo known to occur following brief exposure to a simulated altitude of 2650 m are insufficient to stimulate reticulocyte production. Accepted: 7 October 1999     

Leptin as a marker of training stress in highly trained male rowers?

The purpose of this study was to investigate the potentially important role leptin may play during training monitoring in athletes. Twelve highly trained male rowers underwent a 3-week period of maximally increased training stress followed by a 2-week tapering period. Fasting blood was sampled after a rest day. Subjects also performed a maximal 2000-m rowing ergometer test before and after 3 weeks of heavy training, and after 2 weeks of tapering. Blood samples were obtained before, immediately after and after 30 min of recovery. Leptin concentrations were measured in duplicate by radioimmunoassay. Mean training time was about 100% higher during the heavy training period (17.5 h·week^–1) compared to the tapering period (8.9 h·week^–1). The 3-week heavy training period induced a significant reduction (P<0.05) in the fasting leptin concentration [from 2.5 (0.4) to 1.5 (0.4) ng·ml^–1]. Fasting plasma leptin was significantly increased by the end of the 2-week tapering period [2.0 (0.4) ng·ml^–1] but remained significantly lower compared to the pretraining value. Leptin levels were also significantly decreased only after the 2000-m rowing ergometer test performed at the end of the heavy training period. No differences in leptin concentrations were observed after other performance tests compared to their respective baseline values. In addition, fasting leptin concentration was significantly related to the weekly training time (r=–0.45; P=0.006). In conclusion, it appears that leptin is sensitive to the rapid and pronounced changes in training volume. A greater training time is associated with a lower leptin concentration in highly trained male rowers. It is suggested that it may be possible to direct typical rowing training by monitoring leptin status.     

运动员Lisfranc损伤的诊疗策略及研究进展

BACKGROUND: Lisfranc injury is a concealed or low-energy damage in the athletic population. The optimal treatment strategies for Lisfranc injury in the athletes, especially for high-level or professional athletes, remain controversial. Improvement and development in treatment for Lisfranc injury are ongoing. OBJECTIVE: To summarize the diagnostic and therapeutic strategies and problems in surgery in Lisfranc injuries in the athletic population. METHODS: A computer-based online search was conducted in PubMed and Web of science databases from June 1909 to June 2014 to screen the relevant articles regarding the diagnostic and therapeutic strategies for Lisfranc injury using the key words “Lisfranc, injury, athletes”. The irrelevant and duplicate articles were excluded, and finally 43 articles were reviewed. RESULTS AND CONCLUSION: With the improvement and development in the therapeutic methods for Lisfranc injury, suture button fixation and bioabsorbable screw technology, as novel treatment strategies, have the potential to help restore and/or preserve stability at the tarsometatarsal joints, to avoid the potential risk for internal fixation irritation or the need for removal of hardware after fixation. However, more multi-center, prospective, randomized controlled clinical trials are required for seeking the optimal treatment for Lisfranc injury. For the athletes with Lisfranc injury, the best treatment option, removal timing of internal fixation devices, and the proper postoperative function exercise performed according the conditions of patients are vital for restoring the professional sports level. 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Variations in strength-related measures during the menstrual cycle in eumenorrheic women: A systematic review and meta-analysis

ObjectivesTo systematically review the current body of research that has investigated changes in strength-related variables during different phases of the menstrual cycle in eumenorrheic women.DesignSystematic review and meta-analysis.MethodsA literature search was conducted in Pubmed, SPORTDiscus and Web of Science using search terms related to the menstrual cycle and strength-related measures. Two reviewers reached consensus that 21 studies met the criteria for inclusion. Methodological rigour was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Random effects meta-analyses were used to compare the early-follicular, ovulatory and mid-luteal phases for maximal voluntary contraction, isokinetic peak torque, and explosive strength.ResultsThe assessment of study quality showed that a high level of bias exists in specific areas of study design. Non-significant and small or trivial effect sizes (p ≥ 0.26, Hedges g ≤ 0.35) were identified for all strength-related variables in each comparison between phases. 95% confidence intervals for each comparison suggested the uncertainty associated with each estimate extends to a small effect on strength performance with unclear direction (−0.42 ≤ g ≤ 0.48). The heterogeneity for each comparison was also small (p ≥ 0.83, I² = 0%).ConclusionsStrength-related measures appear to be minimally altered (g ≤ 0.35) by the fluctuations in ovarian sex hormones that occur during the menstrual cycle. This finding should be interpreted with caution due to the methodological shortcomings identified by the quality assessment.     

The association of low back pain, neuromuscular imbalance, and trunk extension strength in athletes

BACKGROUND CONTEXT: Imbalanced patterns of erector spinae activity and reduced trunk extension strength have been observed among patients with low back pain (LBP). The association between LBP and neuromuscular imbalance still remains unclear. PURPOSE: To examine the relationship between LBP, neuromuscular imbalance, clinical symptoms, and trunk extension strength on two independent occasions, after dynamic neuromuscular changes through a back exercise program. STUDY DESIGN/SETTING: Experimental longitudinal study of the lower back in a clinical setting. PATIENT SAMPLE: Eighty-two elite amateur tennis players with and without LBP. OUTCOME MEASURES: Clinical testing of spinal mobility and muscular flexibility of the lower back. Isometric voluntary maximum trunk extension strength. Surface electromyography (EMG) of lumbar erector spinae. METHODS: Athletes underwent a standardized clinical examination with common tests for spinal mobility and muscular flexibility, followed by an isometric trunk extension tests in a specially built apparatus with simultaneous surface EMG recording from right and left lumbar erector spinae. Imbalance quotients were calculated using integrated EMG (IEMG) measures. The relationships between LBP, neuromuscular imbalance, trunk extension strength, and clinical findings were investigated before and after a back exercise program using univariate and multivariate logistic regression models. RESULTS: A significant association between neuromuscular imbalance of erector spinae and the occurrence of LBP was observed, whereas no significant imbalances were found in subjects without LBP. The number of subjects with LBP decreased proportionally with the occurrence of neuromuscular imbalance in the lumbar region after the completion of a back exercise program. However, neuromuscular imbalances were still present during retesting among subjects whose LBP did not resolve; the relationship between neuromuscular imbalance of lumbar erector spinae and LBP was significant again. On the contrary, no significant association between LBP and maximum isometric trunk extension strength or neuromuscular imbalance and maximum isometric trunk extension strength was found before or after the exercise program. No clear relationship between LBP and clinical testing of the lumbar spine or neuromuscular imbalance and clinical testing was found on the two independent testing occasions. CONCLUSION: A direct relationship between LBP and neuromuscular imbalance was documented in athletes with LBP. Maximum isometric trunk extension strength had no relationship to the presence of LBP or the occurrence of neuromuscular imbalance of erector spinae. Common clinical testing of spinal mobility and muscular flexibility had only limited correlation to LBP and neuromuscular imbalance.     

Nutrient intake,meal timing and sleep in elite male Australian football players

ObjectivesTo investigate the relationship between dietary intake, meal timing and sleep in elite male Australian football players.DesignProspective cohort study.MethodsSleep and dietary intake were assessed in 36 elite male Australian Football League (AFL) players for 10 consecutive days in pre-season. Sleep was examined using wrist activity monitors and sleep diaries. Dietary intake was analysed using the smartphone application MealLogger and FoodWorks. Generalised linear mixed models examined the associations between diet [total daily and evening (>6 pm) energy, protein, carbohydrate, sugar and fat intake] and sleep [total sleep time (TST), sleep efficiency (SE), wake after sleep onset (WASO) and sleep onset latency (SOL)].ResultsTotal daily energy intake (MJ) was associated with a longer WASO [β = 3, 95%CI: 0.2–5; p = 0.03] and SOL [β = 5, 95%CI: 1?9; p = 0.01]. Total daily protein intake (g kg^?1) was associated with longer WASO [β = 4, 95%CI: 0.8?7; p = 0.01] and reduced SE [β = ?0.7 CI: ?1.3 to ?0.2; p = 0.006], while evening protein intake (g kg^?1) was associated with shortened SOL [β = ?2, 95%CI: ?4 to ?0.4), p = 0.02]. Evening sugar intake (g kg^?1) was associated with shorter TST [β = ?5, 95%CI: ?10 to ?0.6; p = 0.03] and WASO [β = ?1, 95%CI: ?2 to ?0.3; p = 0.005]. A longer period between the evening meal consumption and bedtime was associated with a shorter TST [β = ?8, 95%CI: ?16 to ?0.3; p = 0.04].ConclusionsEvening dietary factors, including sugar and protein intake, had the greatest association with sleep in elite male AFL players. Future research manipulating these dietary variables to determine cause and effect relationships, could guide dietary recommendations to improve sleep in athletes.     

Prevalence of urinary incontinence among elite athletes of both sexes

ObjectivesTo determine the prevalence of urinary incontinence (UI) among elite athletes and to compare prevalences between sexes and across different sports modalities.MethodsThis was a cross-sectional, observational study conducted in 754 elite athletes (455 women or girls and 299 men or boys). Participants completed a questionnaire to collect self-reported anthropometric measures, medical history and sport-related data, and the questionnaires International Consultation on Incontinence Questionnaire-UI Short-Form (ICQ-UI SF), Three Incontinence Questions (3IQ) and Incontinence Severity Index (ISI).ResultsAccording to replies to the ICQ-UI SF questionnaire, 33% of the athletes had UI at a mean age of 23.75 ± 7.74 years. Prevalences were 45.1% in female compared to 14.7% male athletes (p < 0.001) such that females were 5.45 times more likely to suffer this condition. In 59.9%, incontinence was stress UI. In 30.9%, UI was described as moderate to severe (according to ISI), and quality of life related to UI was scored 4.35 ± 2.98 out of 10 (ICQ-UI SF). 22.7% reported they had experienced urine leakage while training; in 40.5% this occurred when jumping, in 19.6% while running and in 20.2% in different situations.ConclusionsThe prevalence of UI observed in elite athletes was 33%. This prevalence was greater in females and also varied according to the sport practised.     

银质针配合药物注射治疗运动员慢性软组织损伤的研究

目的探讨银质针配合药物注射治疗运动员慢性软组织损伤的临床疗效。方法100例患者随机分为两组,治疗组52例,对照组48例。治疗组采用银质针导热疗法,对照组采用毫针丛刺法,对两组病例的疗效进行比较。结果两组患者近期治疗效果及6个月后治疗效果比较,差异有统计学意义(P0.05)。结论银质针配合药物注射治疗运动员慢性软组织损伤具有较好的远期疗效。     

Attachment and alcohol use amongst athletes: The mediating role of conscientiousness and alexithymia

Objective

The present study aims to explore the mediating effects of conscientiousness and alexithymia in the relationship between parental attachment style and alcohol use in a large sample of athletic young people.

Method

Participants included 434 French sport sciences students. Alcohol use, parental attachment style, conscientiousness and alexithymia were assessed. The hypotheses were tested by using regression and bootstrapping mediation analyses.

Results

Maternal insecure attachment style is positively associated with alcohol use. The current study highlights a multiple pathway in this relationship. The results reveal the mediating effect of low conscientiousness and alexithymia between maternal insecure attachment and alcohol use.

Conclusion

Athletes' alcohol use seems to be the result of a complex association of underlying psychological factors.