长期耐力训练对武警战士运动和静息状态血压的影响

 目的本研究结合武警部队战士训练大纲和训练实际,研究耐力性训练对武警战士血压的影响,为科学训练与监控提供基础资料.方法采用持续跑、间歇跑进行为期12周的耐力训练,测量训练前后运动和静息状态血压的变化.结果武警战士经过阶段性耐力训练后,静息状态下,SBP从(115.15±9.26)mmHg降为(110.82±8.84)mmHg,平均下降了4.33mmHg(P＜0.01);DBP下降了1.6 mmHg(P＞0.05).一次性耐力运动负荷的测试结果表明,实验后运动即刻SBP、DBP和实验前相比分别下降了4.44mmHg和2.18 mmHg(均为P＞0.05).恢复期5 min的比较结果为:SBP分别为(128.18±8.91)mmHg和(122.56±5.07)mmHg(P＜0.05);DBP分别为(72.18±5.41)mmHg和(71.43±4.81)mmHg(P＞0.05).结论长期耐力训练对武警战士运动和静息状态血压产生有利的影响.     

Multiple pulmonary embolisms in a male marathon athlete: Is intense endurance exercise a real thrombogenic risk?

Intense endurance exercise could be associated with multiple thrombogenic risk factors, including dehydration, hemoconcentration, inflammation, and injuries. Despite an increasing number of reported cases of deep venous thrombosis (DVT) in athletes that is raising awareness in the medical community, the prevalence is not well established and evidenced‐based guidelines for management of this clinical scenario are lacking. We present an episode of unprovoked DVT and multiple pulmonary embolisms with severe right ventricular dysfunction in a male runner. We highlight the challenge of diagnosing DVT and pulmonary embolism in athletes due to frequently atypical symptomatology and the emergent need for longitudinal studies to evaluate their thrombogenic risk and develop specific guidelines in this field.     

Caffeine has a small effect on 5-km running performance of well-trained and recreational runners

The purpose of this study was to investigate if caffeine ingestion improves 5-km time-trial performance in well-trained and recreational runners. Using a double-blind placebo-controlled design, 15 well-trained and 15 recreational runners completed two randomized 5-km time-trials, after ingestion of either 5mgkg(-1) of caffeine or a placebo. Caffeine ingestion significantly improved 5-km running performance in both the well-trained and recreational runners. In comparison to the placebo trial, the caffeine trial resulted in 1.1% (90% CI 0.4-1.6) and 1.0% (0.2-2%) faster times for the well-trained and recreational runners. Reliability testing of the recreational runners indicated a test-retest error of measurement of 1.4%. We conclude that caffeine ingestion is likely to produce small but significant gains in 5-km running performance for both well-trained and recreational runners.     

锌对小鼠在高温环境下机体耐力的影响(论著)

目的：观察锌对热应激小鼠机体耐力的影响。方法：进行３种试验，即游泳试验、耐缺氧试验和高温致死试验。作各种试验的小鼠分别再分为高锌组、中锌组和低锌组，并喂以相应的高、中、低锌饲料２１天（高温致死试验为１４天）。每日光暗节律各１２小时，自由摄食与饮水，同时观察动物活动、皮毛、摄食及体重情况。游泳试验水温为４０．０±０．２℃，记录小鼠入水游泳至沉底死亡的时间。耐缺氧试验在高温室（干球３９℃、湿球３４℃）内进行，记录小鼠在腊封瓶内的存活时间。高温致死试验在ＤＬ－３０１Ａ型调温调湿箱（干球４６℃，湿球４１℃）内进行，观察３０分钟内的各组动物死亡数。结果：①高锌组小鼠游泳时间显著长于中、低锌组；②高锌组小鼠耐缺氧时间显著长于低锌组；③高锌组小鼠的３０分钟致死率显著低于低锌组。结论：适量补锌可以增强小鼠在高温环境下的热耐受能力     

Is the gut microbiota bacterial abundance and composition associated with intestinal epithelial injury,systemic inflammatory profile,and gastrointestinal symptoms in response to exertional-heat stress?

ObjectivesThe study aimed to examine if the α-diversity and relative abundance of the gastrointestinal bacterial taxa is associated with the response magnitude of markers characteristic of exercise-induced gastrointestinal syndrome in response to exertional-heat stress.DesignCross-sectional.MethodsTwenty-two endurance-trained athletes completed 2 h running at 60% $\stackrel{.}{V}$O_2max in hot ambient conditions (35.2 °C, 25% relative humidity). Faecal samples were collected pre-exercise to determine bacterial taxonomy by 16S rRNA amplicon sequencing (Illumina MiSeq platform). Data were processed using the QIIME2 pipeline (v2019.1) establishing taxonomic classification with >95% confidence using SILVA. Pre- and post-exercise blood samples were used to determine plasma I-FABP and cortisol concentrations, and systemic inflammatory response profile. Markers of physiological and thermoregulatory strain, and gastrointestinal symptoms were measured every 10 min during exercise. Associations were determined by partial correlation controlled for body mass variables.ResultsPositive associations between Tenericutes (r₍₁₈₎ = 0.446, p = 0.049) and Verrucomicrobia (r₍₁₈₎ = 0.450, p = 0.046) phylum, Akkermansiaceae (r₍₁₈₎ = 0.486, p = 0.030) and Ruminococcaceae (r₍₁₈₎ = 0.449, p = 0.047) family and aligned genus groups with I-FABP were observed. Whilst, associations between Faecalibacterium (r₍₁₂₎ = 0.668, p = 0.009) and Ruminoclostridium-9 (r₍₁₂₎ = −0.577, p = 0.031) genus with systemic inflammatory profile were observed. Association between bacterial phyla, family, and genus groups were also observed for gastrointestinal symptoms and markers of thermoregulatory strain (r₍₁₈₎ >0.400, p < 0.05).ConclusionsThe relative abundance of several commensal bacterial groups showed modest favourable (i.e., low perturbations) or detrimental associations with the magnitude of gastrointestinal integrity perturbations and symptoms, and potentially influences body temperature change, in response to exertional-heat stress.     

Effects of carbohydrate dose and frequency on metabolism,gastrointestinal discomfort,and cross‐country skiing performance

This study investigated carbohydrate ingestion of varied doses and frequencies during a simulated cross‐country skiing time trial. Ten men and three women (age: 30 ± 7 years; : 59.6 ± 5.7 mL/kg/min) completed four, 30‐km classic technique roller skiing time trials on a treadmill. A 1:1 maltodextrin‐fructose carbohydrate solution was provided at high (2.4 g/min; HC) and moderate (1.2 g/min; MC) ingestion rates, each at high (six feeds; HF) and low (two feeds; LF) frequencies. In the LF trials, blood glucose was elevated following carbohydrate ingestion (at 4 and 19 km) but was reduced at 14 and 29 km compared with HF strategies (P ≤ 0.05). Gastrointestinal discomfort was higher in HC‐LF compared with all other trials (P ≤ 0.05). Whole‐body lipid oxidation was lower and carbohydrate oxidation was higher in LF compared with HF trials (P ≤ 0.05). While performance time was not significantly different between trials (140:11 ± 15:31, 140:43 ± 17:40, 139:12 ± 15:32 and 140:33 ± 17:46 min:s in HC‐HF, HC‐LF, MC‐HF, and MC‐LF, respectively; P > 0.05), it was improved with trial order (P < 0.001). There was no effect of order on any other variable (P > 0.05). Altering carbohydrate dose or frequency does not affect cross‐country ski performance. However, low‐frequency carbohydrate ingestion resulted in poorer maintenance of euglycemia, reduced lipid oxidation, and increased gastrointestinal discomfort.     

Glucose‐fructose likely improves gastrointestinal comfort and endurance running performance relative to glucose‐only

This study aimed to determine whether glucose‐fructose (GF) ingestion, relative to glucose‐only, would alter performance, metabolism, gastrointestinal (GI) symptoms, and psychological affect during prolonged running. On two occasions, 20 runners (14 men) completed a 120‐min submaximal run followed by a 4‐mile time trial (TT). Participants consumed glucose‐only (G) or GF (1.2:1 ratio) beverages, which supplied ～ 1.3 g/min of carbohydrate. Substrate use, blood lactate, psychological affect [Feeling Scale (FS)], and GI distress were measured. Differences between conditions were assessed using magnitude‐based inferential statistics. Participants completed the TT 1.9% (?1.9; ?4.2, 0.4) faster with GF, representing a likely benefit. FS ratings were possibly higher and GI symptoms were possibly‐to‐likely lower with GF during the submaximal period and TT. Effect sizes for GI distress and FS ratings were relatively small (Cohen's d = ～0.2 to 0.4). GF resulted in possibly higher fat oxidation during the submaximal period. No clear differences in lactate were observed. In conclusion, GF ingestion – compared with glucose‐only – likely improves TT performance after 2 h of submaximal running, and GI distress and psychological affect are likely mechanisms. These results apply to runners consuming fluid at 500–600 mL/h and carbohydrate at 1.0–1.3 g/min during running at 60–70% VO_2peak.     

The associations between training load and baseline characteristics on musculoskeletal injury and pain in endurance sport populations: A systematic review

Objectives

To determine the associations between training load, baseline characteristics (e.g. age or previous injury) and rate of musculoskeletal injury and/or pain specifically within an Endurance Sporting Population (ESP).

Optimising training adaptations and performance in military environment

Objectives

Worldwide decreases in physical fitness and increases in body fat among youth have set challenges for armed forces to recruit physically capable soldiers. Therefore, knowledge of optimizing physical adaptation and performance through physical training is vital. In addition, maintaining or improving physical performance among professional soldiers in various military environments is crucial for overall military readiness. The present review focuses on the effects of military training on physical performance by searching for optimal methods to do it.

The effect of compression socks worn during a marathon on hemostatic balance

Introduction. Marathon running evokes parallel increases in markers of coagulation and fibrinolysis (i.e. hemostatic activation) immediately following strenuous, endurance exercise such that hemostatic balance is maintained. However, other factors incident to marathon running (i.e. dehydration, travel) may disproportionately activate the coagulatory system, increasing blood clot risk after an endurance event in otherwise healthy individuals. We investigated the effect of compression socks on exercise-induced hemostatic activation and balance in endurance athletes running the 2013 Hartford Marathon. Methods. Adults (n = 20) were divided into compression sock (SOCK; n = 10) and control (CONTROL; n = 10) groups. Age, anthropometrics, vital signs, training mileage and finishing time were collected. Venous blood samples were collected 1 day before, immediately after and 1 day following the marathon for analysis of coagulatory (i.e. thrombin–antithrombin complex [TAT] and D-dimer) and fibrinolytic (i.e. tissue plasminogen activator [t-PA]) factors. Results. Plasma D-dimer, TAT and t-PA did not differ between groups at baseline (p > 0.16). There were no significant group · time interactions (all p ≥ 0.17), however, average t-PA was lower in SOCK (8.9 ± 0.7 ng/mL) than CONTROL (11.2 ± 0.7 ng/mL) (p = 0.04). Average TAT also tended to be lower in SOCK (2.8 ± 0.2 µg/L) than CONTROL (3.4 ± 0.2 µg/L) (p = 0.07). Conclusions. Our results suggest that overall hemostatic activation (both coagulation and fibrinolysis) following a marathon tended to be lower with compression socks. Thus, compression socks do not adversely influence markers of hemostasis, appear safe for overall use in runners and may reduce exercise-associated hemostatic activation in individuals at risk for deep vein thrombosis.     

Emotional intelligence and mood states impact on the stress response to a treadmill ultramarathon

ObjectivesParticipants of ultramarathon events experience a complex interaction of psychophysiological stressors. Therefore, the purpose of this study was to investigate the role of trait emotional intelligence (trait EI) on mood states and serum cortisol responses to a 80.5 km treadmill ultramarathon.DesignTwelve participants completed an 80.5 km time-trial on a motorised treadmill in the fastest possible time.MethodsParticipants’ trait EI was measured prior to the trial. A mood state questionnaire was completed prior (baseline: within two weeks of treadmill ultramarathon), immediately prior (pre: within 30 min of commencing treadmill ultramarathon), at 40.25 km (halfway: during standardised 10 min rest period to allow for venous blood sampling) and on completion of 80.5 km (post: immediately on completion of treadmill ultramarathon), along with serum cortisol concentrations measured at the same time points.ResultsCompletion time was 09:00:18 ± 01:14:07 (hh mm ss). Significant increase in serum cortisol and total mood disturbance (TMD) was observed throughout the treadmill ultramarathon (p < 0.05). Participants with higher trait EI displayed a higher post cortisol concentration (p = 0.01) with no change in TMD, compared to those with low trait EI who displayed a significant increase in TMD between pre and halfway (p = 0.02).ConclusionsThe treadmill ultramarathon elicited a significant increase in serum cortisol concentration, which was significantly greater in those with a higher trait EI. Those individuals with higher trait EI were more effective at managing their mood, with little change total mood disturbance and perceived effort compared to those with lower trait EI.     

Sodium phosphate loading improves laboratory cycling time-trial performance in trained cyclists

Sodium phosphate loading has been reported to increase maximal oxygen uptake (6–12%), however its influence on endurance performance has been ambiguous. The aim of this study was to examine the influence of sodium phosphate loading on laboratory 16.1 km cycling time-trial performance. Six trained male cyclists ( peak, 64.1 ± 2.8 ml kg⁻¹ min⁻¹; mean ± S.D.) took part in a randomised double-blind crossover study. Upon completion of a control trial (C), participants ingested either 1 g of tribasic dodecahydrate sodium phosphate (SP) or lactose placebo (P) four times daily for 6 days prior to performing a 16.1 km (10 mile) cycling time-trial under laboratory conditions. Power output and heart rate were continually recorded throughout each test, and at two points during each time-trial expired air samples and capillary blood samples were taken. There was a 14-day period between each of the supplemented time-trials. After SP loading mean power was greater than for P and C (C, 322 ± 15 W; P, 317 ± 16 W; SP, 347 ± 19 W; ANOVA, P < 0.05) and time to complete the 16.1 km was shorter than P, but not C (ANOVA, P < 0.05). During the SP trial, relative to the P, mean changes were mean power output +9.8 ± 8.0% (±95% confidence interval); time −3.0 ± 2.9%. There was a tendency towards higher after SP loading (ANOVA, P = 0.07). Heart rate, , RER and blood lactate concentration were not significantly affected by SP loading. Sodium phosphate loading significantly improved mean power output and 16.1 km time-trial performance of trained cyclists under laboratory conditions with functional increases in oxygen uptake.     

The master female triathlete

The world of triathlon has expanded to include all ages and both sexes. One of the largest growing age groups is the master female athlete. It is important for the physical therapist to understand the special needs of this population in order to adequately care for master female athletes so they can participate at a high level and injury-free. Biology of aging, injury prevention and a suggested training program are presented in this Masterclass article.