Abstract
ground: Participation in triathlon competitions has increased in recent years. Many studies have described left or right ventricular injury in endurance athletes. The goal of this study was to examine the right and left ventricular cardiac structures and function and dynamic cardio-pulmonary performance in a large cohort of middle- and long-distance triathletes. Methods: 87 triathletes (54 male and 33 female) were examined using spiroergometry and echocardiography. The inclusion criterion was participation in at least one middle- or long distance triathlon. Results: Male triathletes showed a maximum oxygen absorption of 58.1 ± 8.6 mL/min/kg (female triathletes 52.8 ± 5.7 mL/min/kg), maximum ergometer performance of 347.8 ± 49.9 W (female triathletes 264.5 ± 26.1 W). Left ventricular ejection fraction (EF) was normal (male triathletes EF: 61.9% ± 3%, female triathletes EF: 63.0% ± 2.7%) and systolic right ventricular area change fraction (RV AFC%) showed normal values (males RV AFC%: 33.5% ± 2.2%, females 32.2% ± 2.8%). Doppler indices of diastolic function were normal in both groups. With respect to the echocardiographic readings the left ventricular mass for males and females were 217.7 ± 41.6 g and 145.9 ± 31.3 g, respectively. The relative wall thickness for males was 0.50 ± 0.07, whereas it was 0.47 ± 0.09 for females. The probability of left ventricular mass >220 g increased with higher blood pressure during exercise (OR: 1.027, CI 1.002–1.052, p = 0.034) or with higher training volume (OR: 1.23, CI 1.04–1.47, p = 0.019). Conclusions: Right or left ventricular dysfunction could not be found, although the maximal participation in triathlon competitions was
whereas it was 0.47 ± 0.09 for females. The probability of left ventricular mass >220 g increased with higher blood pressure during exercise (OR: 1.027, CI 1.002–1.052, p = 0.034) or with higher training volume (OR: 1.23, CI 1.04–1.47, p = 0.019). Conclusions: Right or left ventricular dysfunction could not be found, although the maximal participation in triathlon competitions was 29 years. A left ventricular mass OPEN ACCESS
Int. J. Environ. Res. Public Health 2014, 11 9083 >220 g is more likely to occur with higher arterial pressure during exercise and with a higher training volume. Keywords: endurance sport; cardiac injury; triathlon; marathon 1. Introduction The possibility of myocardial damage due to physical activity has been known since ancient times. According to legend, a soldier named Pheidippides (more likely Philippides) dropped dead after running to Athens from the battle at Marathon with the news of victory [1]. A soldier or courier, he is purported to have already run 240 km from Athens to Sparta and back before running a marathon distance to Athens, and the truth about his story is unknown [2]. What is clear, however, is that this death is the first recorded sport-related death. Some papers have reported on common deaths in triathlon competitions [3] and exercise-induced cardiac fatigue in triathlon competitions [4,5] and other endurance disciplines [6,7]. The problem of cardiac injury with endurance sports is a complex issue [7–9]. Figure 1 shows some factors that might influence cardiac injury in endurance athletes. Figure 1. Factors that might influence heart function during endurance sport.
Int. J. Environ. Res. Public Health 2014, 11 9084 Triathlon is an endurance sport, especially when performed in middle- and long-distance formats (e.g., middle/long distance Ironman: a 1.9/3.8 km swim, a 90/180 km bicycle ride and a 21.1/42.2 km run), mainly under aerobic conditions. It is particularly important for triathletes to perform at sub-maximal levels over a long period to avoid reaching a state of exhaustion [10,11]. Amateur athletes typically take 5 to 6.5 h for middle-distance events and 10 to 16 h for long-distance events. Such long periods of stress require that both the amateur and the top athletes be adequately trained and have sufficient aerobic capacity [10]. A number of studies with small cohorts have reported spiroergometric data [12–15]. Problems regarding the condition of athletes‘ hearts have been identified [16]. These problems are mainly known from observations of professional cyclists [17] and elite runners [18]. Regarding the literature about ―exercise-induced‖ cardiac fatigue and ―athlete‘s heart‖, the following questions have to be asked: - Are there signs of cardiac ―fatigue‖ when triathletes have trained hard over a period of years? Are there risks for right ventricular or left ventricular dysfunction for amateur athletes? - What type of athletes‘ hearts or what type of hypertrophy, concentric or eccentric, is found most often in triathletes? - Are there signs of reduced physiological performance? 2. Experimental Section 2.1. Participants Eighty-seven triathletes were examined, including 54 males and 33 females. All triathletes were examined by echocardiography (except three males) and spiroergometry. Triathletes underwent their annual medical check-up or examination for training preparation in 2011/2012, which would have been performed as part of the normal clinical routine. All examinations were performed by Dr. Roman Leischik or Dr. Norman Spelsberg. The participants were invited to participate in the study during their routine check-up or routine training preparation, and announcements in social media and triathlon clubs were also made. Dr. Roman Leischik is the medical supervisor of the Triathlon Club PV-Witten since 2007. This study was prospective in design. 2.2. Methods: Echocardiography and Spiroergometry A Vivid 7 echocardiograph, produced by General Electric (Fairfield, CT, USA) was
participate in the study during their routine check-up or routine training preparation, and announcements in social media and triathlon clubs were also made. Dr. Roman Leischik is the medical supervisor of the Triathlon Club PV-Witten since 2007. This study was prospective in design. 2.2. Methods: Echocardiography and Spiroergometry A Vivid 7 echocardiograph, produced by General Electric (Fairfield, CT, USA) was used for the examinations. The Ergobike 8I, produced by Daum (Fürth, Germany), and the Metalizer 3B, produced by Cortex (Leipzig, Germany), were used for the spiroergometric examination. To compare the data from elite triathletes with those of non-elite triathletes, both males and females were divided into two groups according to their aerobic capacity (relative VO2/min/kg at the aerobic threshold). The 20 males and 15 females with the highest values were designated as elite. All triathletes were examined in a single day using first echocardiography and then spiroergometry. All examinations were performed in 2011 and 2012 at the Sports Medicine Center, Hagen, Germany. The spiroergometry was performed in the following manner: the stress test was conducted in stages after successful gas and volume calibration at 50 W for 3 min, 100 W for an additional 3 min, after which it increased by another 30 W for 3 minutes. The test ended when the subject was exhausted.
Int. J. Environ. Res. Public Health 2014, 11 9085 The echocardiographic analysis was conducted according to general recommendations [19,20]. The formula recommended by the American Society of Echocardiography (ASE) was used to calculate the muscle mass. EDV and ESV were determined as monoplane by the modified Simpson method. The spiroergometric analyses were conducted according to the literature. VAT was determined as the first non-linear increase in the ventilatory equivalent for oxygen without a simultaneous increase of the ventilatory equivalent for CO 2 . RCP was determined as a simultaneous non-linear increase of both ventilatory equivalents according to recommendations [21,22]. VO2max was registered as the highest average value of oxygen absorption over 30 seconds. Elite triathletes were identified by their aerobic capacity. The 20 males and 15 females with the best values of relative oxygen uptake (in mL/min/kg) were classified as elite. 2.2.1. Ethics Statement All athletes gave verbal and written consent to voluntary performance testing and for use of their data in this study. All data were anonymized. Triathletes underwent their annual medical check-up or examination for training preparation in 2011/2012, which would have been performed in any case as it is clinical routine. The study was approved as a doctoral dissertation by the Dissertation Audit Committee of the University Witten/Herdecke. All examinations (echocardiography and spiroergometry) were a part of the routine clinical and diagnostic care for the triathletes. All examinations were performed by two experienced investigators (see chapter methods). This study did not introduce any pharmaceutical interventions or changes in the clinical course of the triathletes. 2.2.2. Statistical Analyses The entire statistical analysis was designed as follows. Stata/IC 11.2 for Windows was used for data preparation and statistical analysis. The Mann-Whitney U-Test was used to compare the groups. The Kaplan-Meier product limit method and the Cox proportional hazards model were used to estimate the odds ratios for analysis of the relationship between arterial pressure and the probability of a left ventricular muscle mass (LVM) >220 g. All statistical tests were two-sided, with a significance level of 0.05. 3. Results and Discussion 3.1. Participants Characteristics Anthropometric data and the general
Kaplan-Meier product limit method and the Cox proportional hazards model were used to estimate the odds ratios for analysis of the relationship between arterial pressure and the probability of a left ventricular muscle mass (LVM) >220 g. All statistical tests were two-sided, with a significance level of 0.05. 3. Results and Discussion 3.1. Participants Characteristics Anthropometric data and the general cardiac parameters of the participants are listed in Table 1. Male triathletes have significant greater weight, BMI, and BSA than female triathletes, but lower body fat (12% vs. 22.8%). Heart cavities and stroke volume are significant larger, without differences in systolic function (EF) or diastolic function (Doppler parameters).
Int. J. Environ. Res. Public Health 2014, 11 9086 Table 1. Anthropometric and structural echocardiographic characteristics of the study population. Parameters Male Female Mann-Whitney U-Test p-value n Mv Sd n Mv Sd Age (years) 54 38.1 11.8 33 34.3 8.1 0.137 Weight (kg) 54 76.8 8.9 33 61.5 7.8 0.001 Size (cm) 54 182.4 6.7 33 168.8 6.4 0.001 BMI (kg/m²) 54 23.0 1.83 33 21.6 2.28 0.001 BSA (m²) 54 1.97 0.14 33 1.70 0.13 0.001 %body fat 54 12.5 3.6 33 22.8 4.7 0.001 Ao 51 2.90 0.37 33 2.47 0.24 0.001 LA 51 2.54 0.28 33 2.35 0.25 0.002 LAV (mL) 51 29.1 7.8 33 27.4 9.3 0.254 IVS thickness diastolic (cm) 51 1.23 0.13 33 1.02 0.17 0.001 IVS thickness systolic (cm) 51 1.67 0.18 33 1.44 0.22 0.001 PWT diastolic (cm) 51 1.22 0.14 33 1.02 0.16 0.001 PWTs (cm) 51 1.70 0.17 33 1.48 0.20 0.001 Relative wall thickness 51 0.50 0.07 33 0.47 0.09 0.066 LVEDD (cm) 51 4.8 0.38 33 4.4 0.32 0.001 LVESD (cm) 51 3.3 0.29 33 2.9 0.27 0.001 LVM (g) 51 217.7 41.6 33 145.9 31.3 0.001 LVM (g/m²) 51 110.5 21.8 33 85.8 18.7 0.001 LVEDV (mL) 51 138.5 22.3 33 105.0 17.8 0.001 LVESV (mL) 51 52.7 9.9 33 38.9 7.1 0.001 SV (mL) 51 85.7 14.0 33 66.1 11.3 0.001 EF (%) 51 61.9 3.0 33 63.0 2.7 0.292 LVOT VMax (m/s) 51 0.80 0.13 32 0.86 0.13 0.047 MV EMax (m/s) 51 0.53 0.10 33 0.56 0.12 0.091 MV AMax (m/s) 51 0.36 0.06 33 0.38 0.09 0.569 MV E/A Ratio 51 1.48 0.31 33 1.54 0.34 0.407 RV parasternal 51 3.18 0.13 33 2.40 0.18 0.001 RV AFC% 51 33.5 2.2 33 32.2 2.8 0.005 n = number; Mv = mean value; Sd = standard deviation; BMI = body mass index; BSA = body surface area; Ao = aortic diameter; LA = left atrial diameter in cm; LAV = left atrial end-systolic volume; IVS = interventricular septum; PWT = diastolic posterior wall thickness; PWTs = systolic posterior wall thickness; RWT = relative wall
2.8 0.005 n = number; Mv = mean value; Sd = standard deviation; BMI = body mass index; BSA = body surface area; Ao = aortic diameter; LA = left atrial diameter in cm; LAV = left atrial end-systolic volume; IVS = interventricular septum; PWT = diastolic posterior wall thickness; PWTs = systolic posterior wall thickness; RWT = relative wall thickness (formula: 2 × PWT/LVEDD); LVEDD = left ventricular end- diastolic diameter; LVESD = left ventricular end-systolic diameter; LVM = left ventricular mass; LVM (g/m 2 ) = LVM/BSA; LVEDV = left ventricular end-diastolic volume; LVESV = left ventricular end-systolic volume; d = diastolic; s = systolic; SV = stroke volume; EF = left ventricular ejection fraction in %; LVOT VMax = left ventricular outflow tract velocity; MV EMax = early (E) mitral velocity; MV AMax = mitral A (atrial) velocity; RV parasternal = RV diameter from parasternal view in cm; RV AFC = right ventricular area fractional change in %.
Int. J. Environ. Res. Public Health 2014, 11 9087 3.1.1. Echocardiography Myocardial hypertrophy was common and was classified according to Lang et al. [19] (Tables 2 and 3). Table 2. Myocardial hypertrophy in male triathletes. Left Ventricle Normal Light Moderate Strong LVEDD 51 (100%) 0 0 0 IVSD 3 (5.9%) 39 (76.5%) 9 (17.6%) 0 PWT 4 (7.8%) 37 (72.5%) 10 (19.7%) 0 LVM (g/m²) 31 (60.8%) 11 (21.6%) 7 (13.7%) 2 (3.9%) LVEDV * 44 (86.3%) 4 (7.8%) 2 (3.9%) 1 (2.0%) * Reference values according to Lang et al. [19]; LVEDD: left ventricular end-diastolic diameter; IVSD: interventricular septum diastolic thickness; PWT: diastolic posterior wall thickness; LVM (g/m²): Left ventricular mass/BSA; LVEDV: left ventricular end-diastolic volume. Table 3. Myocardial hypertrophy in female triathletes. Left Ventricle Normal Light Moderate Strong LVEDD 33 (100%) 0 0 0 IVSD 12 (36.4%) 18 (54.5%) 3 (9.1%) 0 PWT 12 (36.4%) 18 (54.5%) 3 (9.1%) 0 LVM (g/m²) 26 (78.8%) 4 (12.1%) 1 (3.0%) 2 (6.1%) LVEDV * 18 (54.5%) 5 (15.2%) 8 (24.2%) 2 (6.1%) * Reference values according to Lang et al. [19]; LVEDD: left ventricular end-diastolic diameter; IVSD: interventricular septum-end-diastolic thickness; PWT: diastolic posterior wall thickness; LVM (g/m²): Left ventricular mass/BSA; LVEDV: left ventricular end-diastolic volume. In the study population, concentric changes of the left ventricle characterized the echocardiographic morphological picture. Concentric remodeling for males was found in 26 cases and concentric hypertrophy was observed in 21 cases. One male triathlete had eccentric hypertrophy, and three had normal myocardial anatomy. Seventeen females displayed concentric remodeling, and 6 females had concentric hypertrophy. Cardiac adaptation forms are visualized in Table 4. Table 4. Cardiac adaptation in the study collective *. RWT >0.42 cm Concentric Remodeling Concentric Hypertrophy Males: 26 Males: 21 Females: 17 Females: 6 RWT <0.42 cm Normal Eccentric Hypertrophy Males: 3 Males: 1 Females: 9 Females: 1 * Reference values and definition according to Lang et al. [19]; RWT: relative wall thickness (formula: 2 × PWT/LVEDD). The classification into types of hypertrophy followed the criteria of Lang et al. [19]. Right ventricular remodeling or other pathological findings in the right ventricle
Females: 6 RWT <0.42 cm Normal Eccentric Hypertrophy Males: 3 Males: 1 Females: 9 Females: 1 * Reference values and definition according to Lang et al. [19]; RWT: relative wall thickness (formula: 2 × PWT/LVEDD). The classification into types of hypertrophy followed the criteria of Lang et al. [19]. Right ventricular remodeling or other pathological findings in the right ventricle were not found. Left ventricular function was excellent in all triathletes, even if they trained hard and had finished middle- or long-distance triathlons.
Int. J. Environ. Res. Public Health 2014, 11 9088 3.1.2. Spiroergometry/Physiological Performance Oxygen absorption, ergometer performance and heart rate with VAT, RCP and at peak capacity are shown in Tables 5 (males) and 6 (females). Table 5. Males: heart rate, oxygen uptake and power output according to performance. Measurements Elite Males Non-Elite Males p-Value * n Mv Sd n Mv Sd AT (aerobic threshold) HR 20 160.4 9.1 34 144.9 13.0 0.000 aVO 2 20 3.85 0.46 34 3.14 0.52 0.000 rVO 2 20 53.1 5.2 34 39.8 5.5 0.000 %VO 2 20 82.4 6.6 34 73.9 11.7 0.004 Watt 20 314.5 47.0 34 259.7 44.1 0.000 RCP (respiratory compensatory point, anaerobic threshold) HR 20 170.8 7.4 34 157.7 12.2 0.000 aVO 2 20 4.37 0.61 34 3.59 0.48 0.000 rVO 2 20 60.1 6.6 34 45.4 5.1 0.000 %VO 2max 20 92.3 6.9 34 84.4 10.4 0.003 Watt 20 346.3 48.6 34 289.7 38.2 0.000 Peak capacity HR 20 180.4 7.1 34 144.9 13.0 0.000 aVO 2max 20 4.7 0.7 34 4.3 0.6 0.060 rVO 2max 20 64.7 6.7 34 54.2 7.1 0.000 Watt max 20 367.0 47.6 34 336.5 48.3 0.026 n = number; Mv = mean value; Sd = standard deviation; aVO 2 = absolute VO 2max in L/min; rVO 2 = relative VO 2 in mL/kg −1 ·min −1 ; * = of the Mann-Whitney U-Test; HR = heart rate; Watt = power output. Table 6. Females: heart rate, oxygen uptake and power output according to performance. Measurements Elite Females Non-Elite Females p-Value * n Mv Sd n Mv Sd VAT (ventilatory aerobic threshold) HR 15 160.6 14.5 18 138.6 19.9 0.002 aVO 2 15 2.76 0.35 18 1.99 0.46 0.001 rVO 2 15 45.5 5.4 18 32.7 3.8 0.001 %VO 2max 15 81.2 7.0 18 64.4 12.9 0.001 Watt 15 230.0 24.5 18 162.2 41.4 0.001 RCP (respiratory compensation point, anaerobic threshold) HR 15 169.8 12.6 18 152.3 21.0 0.016 aVO 2 15 3.06 0.28 18 2.33 0.56 0.001 rVO 2 15 46.8 14.9 18 37.4 6.3 0.001 %VO 2max 15 91.7 6.7 18 75.3
Description
The study investigates cardiac injury in recreational Ironman athletes.