Left ventricular volumes and mass in marathon runners and their association with cardiovascular risk factors

Background To assess left ventricular volumes and mass by cardiac magnetic resonance imaging in relation to conventional cardiovascular risk factors and coronary atherosclerotic plaque burden in master marathon runners aged ≥50 years. Methods Cardiac MRI was performed in 105 clinically healthy male marathon runners (mean age 57.3 ± 5.7 years, range 50–71 years) on a 1.5 T MR system (Avanto, Siemens, Germany). Cine steady state free precession images in standard long and short axes views were acquired to assess left ventricular volumes and mass. Cardiovascular risk factors (blood pressure, HDL/LDL cholesterol, smoking, body mass index) were assessed and coronary artery calcification (CAC) was quantified by electron beam computed tomography. Results Left ventricular muscle mass (mean LVMM = 140 ± 27 g; 73 ± 13 g/m2) increased with increasing left ventricular end-diastolic volume (mean LVEDV = 137 ± 32 ml; 72 ± 15ml/m2) (r = 0.41, P < 0.0001) and with systolic (r = 0.33, P = 0.005) and diastolic (r = 0.28, P = 0.005) blood pressures. Left ventricular EDV increased up to the age of 55 years, but decreased thereafter. Runners with LVMM ≥150 g had significantly higher CAC scores than runners with LVMM <150 g (median CAC score 110 vs. 25, P = 0.04). Conclusions Increases in LVMM and LVEDV may not only represent a response to exercise but are dependent on age and blood pressure, also. In addition, a left ventricular hypertrophy without an increase in volume may be an indicator for early subclinical cardiac alterations in response to risk factor exposure.     

Erythrocyte,plasma and urinary magnesium in men before and after a marathon

Summary Erythrocyte, plasma and urinary magnesium (Mg²⁺) concentration was measured in 23 runners before and after a marathon race. Blood samples were drawn from an antecubital vein the morning before the race (baseline), at 3 p.m. (2 h before the start), upon finishing and 12 h later. Compared with the baseline values, the intra-erythrocyte and plasma Mg²⁺ were decreased (p<0.05 or less) immediately after the marathon, from 2.13±0.16 to 2.02±0.18 mmol · l^–1 cells and from 0.88±0.06 to 0.81±0.07 mmol · l^–1 respectively. The Mg²⁺ concentration returned to pre-race values 12 h after completion of the marathon. The urinary Mg²⁺ excretion rate decreased (p<0.001) from 29±13 to 5±3 mol · min^–1 during the marathon and increased (p<0.05) 12 h after the race to 38±18 mol · min^–1. It is concluded that the reduction in plasma Mg²⁺ ion concentration during the marathon cannot be attributed to erythrocyte uptake, urinary excretion or loss in sweat. It is suggested that Mg²⁺ may be released from erythrocytes into the extracellular fluids during sustained exercise and taken up from these fluids by the adipose cells.     

Marathon fatigue: the role of plasma fatty acids,muscle glycogen and blood glucose

Summary The role of carbohydrate depletion in marathon fatigue was examined in 6 marathon runs. Four of the runs were potentially fast-time marathons and culminated in fatigue. The utilization of carbohydrate, lipid and protein, and plasma concentrations of free fatty acids (FFA), glucose and lactate were measured at intervals throughout the runs. The contribution from protein to energy output was low (1–2%). The utilization of lipid was dependent upon plasma concentrations of FFA, which rose throughout the run. The utilization of carbohydrate mirrored that of FFA and thus fell throughout the run. Fatigue was characterized by a drop in running speed, a drop in carbohydrate utilization, an unchanging FFA utilization and a fall in blood glucose. The fall in blood glucose was not seen in the non-fatigued runners. These results are consistent with carbohydrate depletion being the cause of fatigue. The implications of these data are that lipid is the preferred fuel, but is rate-limiting, and that carbohydrate depletion, even though it causes fatigue, ensures an optimal-time marathon.     

马拉松运动员的血液循环基础状态分析

采用无创伤性血液一循环功能测试仪,分析62名马拉松运动员在静息状态下血液循环和流变学状态。马拉松运动员与对照组比较,SV,SI,SWI,EKT和心脏效率增高,而HR,TPR,Rη和HOI降低。可见,马拉松运动员的血液循环基础状态与一般人有明显的差别。     

Influence of prolonged physical exercise on the erythropoietin concentration in blood

Summary Erythropoietin (EPO) and red blood cells were studied in 15 well-trained men before and several times after a marathon run. Changes in red blood cells reflected changes of plasma volume. Immediately after the run, red blood cells were increased due to haemoconcentration, whereas 31 h later the values were decreased due to haemodilution. The EPO concentration was increased 3 h, and more impressive 31 h, after the run. This long-lasting increase in EPO concentration after the marathon run would seem to be responsible for the increased red blood cell mass in long distance runners.     

Comparison of serum cardiac specific troponin-I with creatine kinase,creatine kinase-MB isoenzyme,tropomyosin, myoglobin and C-reactive protein release in marathon runners: cardiac or skeletal muscle trauma?

Problems arise in distinguishing skeletal from cardiac muscle trauma on the basis of serum enzyme tests following severe muscle exercise. The contributions of cardiac and skeletal sources have been assessed in eleven marathon runners by measuring pre- and post-race serum levels of cardiac-specific myofibrillar troponin-I together with total creatine kinase, creatine kinase-MB isoenzyme, myoglobin, myofibrillar tropomyosin and C-reactive protein. Total creatine kinase, creatine kinase-MB isoenzyme, tropomyosin and myoglobin were significantly elevated above pre-race levels in all runners between 1 h and 128 h post-race. Neither mean cardiac troponin-I nor C-reactive protein was elevated post-race. Nine out of sixty-three samples fulfilled conventional positive criteria for cardiac muscle damage on the basis of combined creatine kinase and creatine kinase-MB isoenzyme levels. Six runners had one or more positive samples. No samples had levels above twice the upper normal limit for either cardiac troponin-I or C-reactive protein. Correlation analysis of levels in each sample indicated skeletal and not cardiac muscle as the source of raised serum protein.     

The acute effect of marathon running on plasma lipoproteins in female subjects

Summary The acute effect of running a 42.2 km marathon race on plasma lipoproteins was investigated in 12 female subjects (aged 21 to 41 years). During the race there was a significant increase (P<0.01) in the concentration of total plasma cholesterol. The mean post-race concentration of high density lipoprotein cholesterol (HDL-C) was 64.0±16.2 (SD) mg 100 ml^–1, compared with 52.1±14.0 mg 100 ml^–1 before the race, representing a significant increase (P<0.002). There was no significant difference in the concentration of very low density lipoprotein (VLDL) or low density lipoprotein (LDL) before and after the exercise. The mean concentration of the cholesteryl ester moiety of the HDL increased from 43.7±12.3 to 54.3±15.7 mg 100 ml^–1 (P<0.002), while there was no significant change in the concentration of the unesterified cholesterol, phospholipid, triacylglycerol or protein moieties of the HDL. The relative proportions of apolipoproteins A-I, A-II, C and E remained unchanged during the exercise. The changes in the concentration of each of the lipoprotein fractions observed during the marathon varied considerably between subjects. The individual increases in the concentration of HDL-C ranged from 4.1 to 28.4 mg 100 ml^–1, while both increases and decreases in individual concentrations of VLDL and LDL as well as of total plasma cholesterol were observed. These observations suggest that women undergo greater changes in HDL-C concentration than men during acute exercise, while considerable variation between individuals occurs.     

上海国际马拉松跑者膝关节损伤情况及其影响因素分析

目的:通过问卷调查的方式探讨马拉松跑者膝关节损伤的情况及其影响因素。为后期的马拉松跑者膝关节的损伤康复和预防提供理论依据。方法:在2016年上海国际马拉松赛中随机选取850例全马跑者进行问卷调查,问卷为自行设计,主要包括两方面内容:跑步者的基本信息;膝关节损伤的影响因素。统计方法为交叉表的单因素卡方分析以及向前逐步法二元Logistic回归分析。结果:在有效的800份问卷中,膝关节损伤总的发病率为23%。相比于其他的年龄段,膝关节的损伤在40—50岁这个年龄段最不易发生(P0.05);不同性别的跑者在膝关节处的损伤并没有显著性差异。力量不足(P0.01)、准备活动不足(P0.01)、鞋子不适(P=0.015)、疲劳(P0.01)、姿势不正确(P0.01)、旧伤病(P0.01)这些损伤因素与膝关节损伤之间具有相关性。其中旧伤病(OR=4.873)与力量不足(OR=4.074)是膝关节损伤较高的风险因素。结论:膝关节损伤是马拉松跑者中最为常见的损伤部位,其损伤与力量训练和旧伤病有着较深的联系。建议马拉松跑者平时应注重膝关节周围肌群的训练,保护好以前受过伤的部位,防止二次损伤。     

Muscle mechanical characteristics in fatigue and recovery from a marathon race in highly trained runners

The aim of the present study was to examine muscle mechanical characteristics before and after a marathon race. Eight elite runners underwent a pre-test 1 week before the marathon and post-tests 30 min, two and five-day-post-marathon. Actual marathon race performance was 2:34:40 ± 0:04:13. Energy expenditure at marathon pace (EE_Mpace) was elevated 4% post-marathon (pre: 4,465 ± 91 vs. post 4,638 ± 91 J kg bodyweight⁻¹ km⁻¹, P < 0.05), but was lowered by 6 and 9.5% two- and five-day-post-marathon compared to EE_Mpace pre-marathon. Countermovement jump (CMJ) power decreased 13% post-marathon (pre: 21.5 ± 0.9 vs. post: 18.9 ± 1.2 W kg⁻¹; P < 0.05) and remained depressed two- (18%) and five-day (12%) post-marathon. CMJ force was unaltered across all four tests occasions. Knee extensor and plantar flexor maximal voluntary contraction (MVC) decreased from 176.6 ± 9.5 to 136.7 ± 16.8 Nm and 144.9 ± 8.7 to 119.2 ± 15.1 Nm post-marathon corresponding to 22 and 17%, respectively (P < 0.05). No significant changes were detected in evoked contractile parameters, except a 25% increase in force at 5 Hz, and low frequency fatigue was not observed. In conclusion, leg muscle power decreased acutely post-marathon race and recovered very slowly. The post-marathon increase in EE_Mpace might be attributed to a reduction in stretch shortening cycle efficiency. Finally, since MVC was reduced after the marathon race without any marked changes in evoked muscle contractile properties, the strength fatigue experienced by the subjects in this study seems to be related to central rather than peripheral mechanisms.