Effects of different exercise testing methods on left ventricular deformation and its correlation with cardiopulmonary exercise capacity in competitive athletes – semi-recumbent ergometer vs. treadmill testing

doi:10.21203/rs.3.rs-2725090/v1

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Research Article

Effects of different exercise testing methods on left ventricular deformation and its correlation with cardiopulmonary exercise capacity in competitive athletes – semi-recumbent ergometer vs. treadmill testing

https://doi.org/10.21203/rs.3.rs-2725090/v1

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Background

Global longitudinal strain (GLS) and global myocardial work index (GWI) allow early detection of subclinical changes in left ventricular (LV) systolic function. The aim of the study was to investigate the immediate effects of maximum physical exercise by different exercise testing methods on LV deformation parameters in competitive athletes and to analyze their correlation with cardiopulmonary exercise capacity.

Methods

To reach maximum physical exercise, cardiopulmonary exercise testing (CPET) was performed by semi-recumbent ergometer in competitive handball players (n = 13) and by treadmill testing in competitive football players (n = 19). Maximum oxygen uptake (VO_2max) indexed to body weight (relative VO_2max) was measured in all athletes. Transthoracic echocardiography and blood pressure measurements were performed at rest and five minutes after CPET in all athletes. GLS, GWI and their changes before and after CPET (ΔGLS, ΔGWI) were correlated with (relative) VO_2max.

Results

In handball and football players, GLS and GWI did not differ significantly before and after CPET. There were no significant correlations between GLS and relative VO_2max, but moderate correlations were found between ΔGWI and relative VO_2max in handball (r = 0.631; P = 0.021) and football players (r = 0.592; P = 0.008). Furthermore, handball (46.7 ml/min*kg ± 4.7 ml/min*kg vs. 37.4 ml/min*kg ± 4.2; P = 0.004) and football players (58.3 ml/min*kg ± 3.7 ml/min*kg vs. 49.7 ml/min*kg ± 6.8; P = 0.002) with an increased ΔGWI after CPET showed a significant higher relative VO_2max.

Conclusion

Maximum physical exercise has an immediate effect on LV deformation, irrespective of the used testing method. The correlation of relative VO_2max with ΔGWI, identifies GWI as an echocardiographic parameter for characterizing the current individual training status of athletes.

echocardiography

athletes

cardiopulmonary exercise test

deformation

longitudinal strain

work index

In competitive athletes, transthoracic echocardiography (TTE) is a widely used noninvasive imaging modality that allows the assessment of left ventricular (LV) systolic function by LV ejection fraction (EF) and by LV deformation analysis by speckle tracking^1,2.

Global longitudinal strain (GLS) is defined as the percentage longitudinal shortening (change in length compared to baseline length) during systole. GLS allows early detection of subclinical myocardial damage, e.g., due to myocardial fibrosis^3–8. Normal GLS values range from − 16.0 to -22.0%⁹. Whereas GLS is load-dependent, global myocardial work index (GWI) is a modern echocardiographic deformation parameter that has been shown to be afterload-independent and related to myocardial deformation and contractile function^10,11. For this reason, GWI might offer advantages over GLS in athletes exposed to different afterload conditions during exercise. Normal values of GWI range from 1900 to 2100 mmHg%⁹. In contrast to LVEF, GLS and GWI have been shown to be reliable in distinguishing between physiological adaption (e.g., LV hypertrophy due to exercise) and pathological changes (e.g., hypertrophic cardiomyopathy) in the athletes’ heart^12,13.

Cardiopulmonary exercise testing (CPET) is an established method to characterize the pulmonary, vascular, musculoskeletal, and cardiac system in competitive athletes. Maximum oxygen uptake (VO_2max) is considered the international standard for determining physical capacity. CPET can be helpful to assess and optimize the athlete’s current training condition^14,15,16. Since VO_2max is highly dependent on the athlete’s body type, it is often indexed to body weight (relative VO_2max). In addition to the athlete’s body type, age, gender, and sport type also appear to have a significant impact on VO_2max. In healthy males aged 18 and 30 years, a mean relative VO_2max of 48 ml/min*kg has been reported¹⁷.

In general CPET is performed using a cycle ergometer or treadmill^18,19. The cycle ergometer is well applicable in patients with unfavorable conditions (e.g. obesity, joint issues, deconditioning) and allows convenient intra-test procedures (ECG, blood pressure, blood sampling) due to less movement artefacts. Treadmill ergometry is more susceptible to movement artefacts, yet it allows running at predefined speed and incline, activates more muscle groups and can lead to higher levels of peak oxygen uptake^19,20.

The objective of the present study was to investigate the effect of maximum physical exercise by different testing methods on LV deformation in competitive athletes and to analyze the relationship between cardiopulmonary exercise capacity and LV deformation parameters. We hypothesized that the effect of maximum physical exercise on LV deformation does not differ between the two testing methods and GWI can be used as a surrogate parameter for VO_2max.

Study population and study design

The study population (n = 32) was composed of competitive handball (n = 13) and football (n = 19) players from the first handball and football division in Germany. Handball and football players were considered separately due to their different physical constitution and the cardiovascular demands resulting from different types of exercise. All athletes provided informed consent after full explanation of the purpose and order of all procedures. The study was conducted in accordance with the Declaration of Helsinki and was approved by the ethical committee of the University of Leipzig (073/18-ek).

All athletes were enrolled in the outpatient clinic of cardiology from May until July 2020 (handball players) and in July 2021 (football players). They were tested for SARS-CoV-2 and had a negative PCR test taken at most 48 hours before the examination. All athletes were asymptomatic and completely free of cardiovascular diseases or risk factors. A physical examination including vital parameters was performed in all subjects. Further, an electrocardiogram at rest, incremental CPET, and TTE (before and 5 minutes after CPET) were performed. Blood pressure measurements were performed brachial in suspine position at rest and 5 minutes after CPET at the time when TTE examination was started.

Incremental cardiopulmonary exercise test for handball players

CPET was performed on a semi-recumbent ergometer (GE eBike, GE Healthcare GmbH, Solingen, Germany) at a constant speed of 60–70 revolutions per minute (rpm). The test started at a workload of 50W with an increase of 50W every 3 minutes until volitional exhaustion occurred. Each subject continued for an additional 5-minute recovery period at a workload of 25W. In the CPET, ergospirometry data were collected using a digital spirometer (Vyntus™ CPX, Vyaire Germany, Hoechberg, Germany). Absolut and relative oxygen consumption (VO_2max) were assessed to characterize the respiratory function of athletes. VO_2max, minute ventilation (VE), and heart rate (HR) (GE Cardiosoft, GE Healthcare GmbH, Solingen, Germany) were monitored continuously at rest, during CPET, and during recovery. In addition to VO_2max the individual fitness index for weight-independent comparisons of athletes’ cardiopulmonary exercise capacity was calculated by the following: absolute VO_2max/(weight^0,73)²¹.

Incremental cardiopulmonary exercise test for football players

Run performance diagnostics were done on a treadmill (HP Cosmos, Traunstein, Germany) to determine VO_2max (Comsed, Rome, Italy), peak performance (P_peak), maximum heart rate (HR_max), and lactate threshold (LT), as well as running economy and fractional utilization of VO_2max at LT. The testing protocol contained a 2-phase test consisting of an incremental, sub-maximal exercise test (phase 1) followed by a ramp test (phase 2) interspersed with an 8 min break (4 min active walking at 4 km/h followed by 4 min passive rest)²².

Athletes started the incremental test at 8.0 km/h at a treadmill incline of 0%. The test was completed when i) blood lactate has increased by ≥ 1 mmol/L compared to the previous stage, ii) Borg value was > 17 (on the 6–20 scale), iii) the respiratory exchange ratio was > 1.0 in two consecutive stages. Criteria ii) and iii) were introduced to prevent athletes who do not achieve a blood lactate increase of ≥ 1 mmol/L from becoming prematurely exhausted before the upcoming ramp protocol. The last stage was terminated when the result of the blood lactate level of the previous stage was displayed and was ≥ 1 mmol/L compared with the penultimate stage (generally 1 to 1.5 minutes). The start speed of the ramp test and the speed of LT determined in the incremental test (equal to the speed of the stage before the lactate increase of ≥ 1 mmol/L) were increased by 1 km/h every minute until voluntary exhaustion.

Transthoracic echocardiography

TTE was performed using a Vivid E9 or E95 ultrasound system with a 4Vc phased array probe (GE Healthcare Vingmed Ultrasound AS, Horten, Norway). Post-processing analyses were performed with the EchoPac software (Version 203, GE Healthcare Vingmed Ultrasound AS, Horten, Norway). LV morphology was characterized by LV dimensions (M-Mode) including LV length, relative wall thickness (RWT), LV mass (LVM) (by the Devereux formula), and LV mass index (LVMi) according to current recommendations²³. LV systolic function was characterized by LVEF based on LV end-diastolic (LVEDV) and end-systolic volume (LVESV) assessed by LV biplane planimetry by the modified Simpson’s rule in the apical 2- and 4-chamber view as well as by Cardiac Index (CI) (by Doppler echocardiography)²⁴. Myocardial deformation was characterized by GLS using 2D speckle tracking analysis of the apical long axis-, 2-, and 4-chamber-view according to current recommendations^3,25,26. The endocardial contour was manually adjusted, whereas only segments with accurate tracking were accepted. Tracking areas were manually adjusted to enable full myocardial tracking.

Additionally, GWI was calculated by using the longitudinal strain analysis of the apical LV long axis-, 2-, and 4-chamber-view coupled with the noninvasive blood pressure measurements to attain a pressure-strain loop of the LV²⁷. In all athletes, the change in GLS (ΔGLS) and GWI (ΔGWI) was calculated before compared with after CPET.

Diastolic function was characterized by maximum blood flow velocities (V_max) of E- and A-wave, E/A-ratio, myocardial V_max of e’ and a’ of the basal septal and lateral mitral annulus, septal and lateral E/e´-ratio (including average E’/e’-ratio (septal and lateral)) and systolic pulmonary artery pressure (sPAP) according to current recommendations²⁸.

Statistical analysis

All statistical analyses were performed using SPSS Statistics (version 24.0, IBM, Armonk, NY) and Microsoft Office Excel (version 16.53, Microsoft). Continuous variables were expressed as mean value ± standard deviation (SD). Further, percentage changes after CPET compared to resting conditions were stated. In consideration of the small sample size, we decided to forgo distribution analyses. Statistical significance was accepted for P value < 0.05. The student’s t-test was used to compare the echocardiographic results before and after CPET. Comparisons between more than two groups (subgroup analyses) were performed by one-way Analysis of Variance (ANOVA). Pearson correlation coefficient r was used to test the correlation between different echocardiographic parameters at rest, after CPET and for the percentage change of each parameter after CPET compared to resting conditions: r ≤ 0.5 (poor correlation), r = 0.5–0.7 (moderate correlation) and r ≥ 0.7 (good correlation).

Intra- and interobserver variabilities of main echocardiographic parameters (LV volumes, LVEF, GLS, CI, sPAP) were assessed in randomly selected athletes (n = 10). The second investigator used the same datasets, and both were blinded to each other’s results.

Baseline characteristics of handball and football players are shown in Table 1.

Table 1

Baseline characteristics
	Semi-recumbent ergometer			Treadmill
Mean values ± SD	at rest	after CPET	P value	at rest	after CPET	P value
Age (year)	25.2 ± 3.5	-		22.1 ± 4.7	-
Sex (% of male)	13 (100)	-		19 (100%)	-
Weight (kg)	98.4 ± 8.2	-	-	79.1 ± 10.6	-	-
Height (cm)	193.3 ± 7.5	-	-	181.5 ± 7.8	-	-
BSA (m²)	2.3 ± 0.1	-	-	1.99 ± 0.17	-	-
BMI (kg/m²)	26.3 ± 1.7	-	-	23.9 ± 2.0	-	-
BPs (mmHg)	126.0 ± 10.5	152.6 ± 14.0	< 0.001*	133.8 ± 11.1	149.0 ± 14.7	< 0.001*
BPd (mmHg)	80.8 ± 7.3	65.5 ± 9.7	< 0.001*	82.2 ± 7.7	78.0 ± 10.2	0.090
HR (bpm)	68 ± 9	91 ± 13	< 0.001*	64 ± 12	91 ± 14	< 0.001*
* statistically significant (p < 0.05). SD = standard deviation. BSA = body surface area; BMI = body mass index; BPs = systolic blood pressure; BPd = diastolic blood pressure; HR = heart rate; CPET = cardiopulmonary exercise testing

Semi-recumbent ergometer

Left ventricular volumes were significantly lower after physical exertion compared to resting conditions (Table 2). Left ventricular ejection fraction was similar before and after CPET (Table 2). E/A-ratio was significantly decreased after physical exertion, mainly due to a reduction of the A-wave (Table 3). Myocardial early (e’) diastolic tissue velocities were significantly lower, although this did not lead to a reduction of E/e’, mainly due to consistent passive diastolic filling velocities (E-wave) (Table 3). After CPET sPAP was still in normal ranges.

Table 2

Conventional echocardiographic parameters of left ventricular morphology and function
	Semi-recumbent ergometer			Treadmill
Mean values ± SD	at rest	after CPET	P value	at rest	after CPET	P value
IVSD (mm)	9.9 ± 0.9	10.5 ± 1.1	0.073	9.8 ± 1.8	10.8 ± 1.5	0.009*
PWD (mm)	9.7 ± 1.9	10.0 ± 1.0	0.301	9.4 ± 1.9	9.8 ± 2.5	0.494
LVEDD (mm)	57.5 ± 3.8	54.5 ± 3.5	0.001*	57.5 ± 4.2	53.4 ± 4.1	< 0.001*
LVESD (mm)	35.0 ± 3.3	34.1 ± 3.4	0.359	36.4 ± 4.8	34.5 ± 3.9	0.048*
LVL (mm)	92.9 ± 5.7	91.1 ± 7.5	0.404	91.3 ± 5.6	88.0 ± 5.6	0.0194*
LVM (g)	215.1 ± 39.7	215.0 ± 39.5	0.993	219.4 ± 55.9	221.0 ± 43.0	0.873
LVMI (g/m²)	62.1 ± 3.6	63.1 ± 7.4	0.349	101.4 ± 22.6	110.8 ± 20.3	0.059
RWT	0.32 ± 0.06	0.37 ± 0.04	< 0.001*	0.32 ± 0.07	0.39 ± 0.07	< 0.001*
LVEDV (ml)	162.9 ± 23.5	145.2 ± 20.9	0.010*	164.8 ± 26.8	138.6 ± 24.1	< 0.001*
LVESV (ml)	51.2 ± 11.5	48.5 ± 11.2	0.402	57.5 ± 17.7	50.0 ± 12.7	0.019*
LVSV (ml)	111.7 ± 16.3	96.7 ± 16.4	0.006*	107.3 ± 15.3	88.6 ± 15.0	< 0.001*
EF (%)	68.6 ± 4.4	66.6 ± 6.0	0.089	65.8 ± 6.9	64.3 ± 5.6	0.258
CI (l/m²)	3.1 ± 0.7	3.9 ± 0.8	< 0.001*	3.1 ± 0.6	4.1 ± 0.8	< 0.001*
GLS (%)	-18.8 ± 1.6	-18.1 ± 1.7	0.079	-18.3 ± 1.7	-17.7 ± 1.6	0.119
GWI (mmHg%)	1837.7 ± 316.0	1974.7 ± 222.6	0.197	1899.3 ± 280.7	1963.5 ± 370.0	0.461
* statistically significant (p < 0.05). SD = standard deviation. IVSD = Interventricular septum diameter; PWD = Posterior wall diameter; LVEDD = left ventricular end-diastolic diameter; LVESD = left ventricular end-systolic diameter; LVL = left ventricular length; LVM = left ventricular mass; LVMi = LVM index; RWT = relative wall thickness; LVEDV = left ventricular end-diastolic volume; LVESV = left ventricular end-systolic volume; LVSV = left ventricular stroke volume; EF = ejection fraction; CI = cardiac index; GLS = global longitudinal strain; GWI = Global myocardial work index

Table 3

Parameters of left ventricular diastolic and right ventricular function
	Semi-recumbent ergometer			Treadmill
Mean values ± SD	at rest	after CPET	P value	at rest	after CPET	P value
E-wave (m/s)	0.76 ± 0.15	0.72 ± 0.16	0.385	0.73 ± 0.16	0.71 ± 0.20	0.668
A-wave (m/s)	0.43 ± 0.08	0.64 ± 0.19	0.002*	0.41 ± 0.08	0.60 ± 0.19	< 0.001*
E/A-ratio	1.82 ± 0.50	1.19 ± 0.40	< 0.001*	1.87 ± 0.67	1.24 ± 0.35	< 0.001*
Average e‘	0.16 ± 0.04	0.14 ± 0.02	0.004*	0.15 ± 0.02	0.13 ± 0.02	< 0.001*
Average a‘	0.08 ± 0.01	0.09 ± 0.02	0.097	0.07 ± 0.01	0.09 ± 0.02	< 0.001*
Average e‘/a‘-ratio	1.90 ± 0.29	1.59 ± 0.37	0.011*	1.78 ± 0.49	1.49 ± 0.50	0.021*
Average E/e‘-ratio	4.94 ± 1.11	5.09 ± 1.01	0.602	4.94 ± 1.17	5.39 ± 1.28	0.007*
TAPSE (cm)	2.1 ± 1.3	2.0 ± 0.9	0.652	1.9 ± 0.7	2.0 ± 1.2	0.757
sPAP (mmHg)	25.0 ± 4.3	23.8 ± 3.5	0.879	23.7 ± 2.9	22.5 ± 1.8	0.309
* statistically significant (p < 0.05). SD = standard deviation.

Global longitudinal strain (-18.8 ± 1.6% vs. -18.1 ± 1.7%; P = 0.079) and GWI did not differ before and after CPET (1838 ± 316mmHg% vs. 1975 ± 223mmHg%; P = 0.197). Specifically, GWI increased in eight and decreased in five handball players after CPET (Fig. 1). Athletes with an increase in GWI after CPET showed higher relative VO_2max values (46.7 ml/min*kg ± 4.7 ml/min*kg vs. 37.4 ml/min*kg ± 4.2; P = 0.004) (Fig. 1). Athletes with a decrease in GWI after CPET had the lowest relative VO_2max values (Fig. 1). At maximum physical exercise VO_2max was 4214 ± 489 ml/min and relative VO_2max was 43.1 ± 6.4 ml/min*kg. Calculated fitness index was 149 ± 20 ml/min*kg.

No correlation with VO_2max or relative VO_2max was shown for GLS at rest, after CPET, and ΔGLS. In contrast, there was a correlation between GWI after CPET and VO_2max (r = 0.631; P = 0.021), ΔGWI and VO_2max (r = 0.762; P = 0.002), as well as ΔGWI and relative VO_2max (r = 0.671; P = 0.012; Table 4).

Table 4

Correlations between left ventricular deformation and cardiopulmonary exercise capacity
	Semi-recumbent ergometer		Treadmill
Mean values ± SD	Pearson’s R	P value	Pearson’s R	P value
VO_2max vs. GLS at rest	0.047	0.880	0.219	0.367
VO_2max vs. GLS after CPET	-0.067	0.828	-0.041	0.869
VO_2max vs. ΔGLS	-0.136	0.657	-0.325	0.175
Relative VO_2max vs. GLS at rest	-0.019	0.952	0.008	0.974
Relative VO_2max vs. GLS after CPET	0.112	0.716	0.094	0.701
Relative VO_2max vs. ΔGLS	0.159	0.605	0.093	0.706
VO_2max vs. GWI at rest	-0.428	0.144	0.031	0.901
VO_2max vs. GWI after CPET	0.631	0.021*	0.336	0.160
VO_2max vs. ΔGWI	0.762	0.002*	0.346	0.147
Relative VO_2max vs. GWI at rest	-0.415	0.159	-0.099	0.688
Relative VO_2max vs. GWI after CPET	0.502	0.080	0.459	0.048*
Relative VO_2max vs. ΔGWI	0.671	0.012*	0.592	0.008*
* statistically significant (p < 0.05). SD = standard deviation. VO_2max = maximum oxygen uptake; GLS = global longitudinal strain; GWI = global myocardial work index; CPET = cardiopulmonary exercise testing; Δ = change before and after CPET

Treadmill testing

Global longitudinal strain (-18.3 ± 1.7% vs. -17.7 ± 1.6%; P = 0.119) and GWI did not differ before and after CPET (1899 ± 281mmHg% vs. 1963 ± 370mmHg%; P = 0.461). GWI increased in 11 and decreased in eight football players after CPET (Fig. 1). Athletes with an increase in GWI after CPET showed higher relative VO_2max values (58.3 ml/min*kg ± 3.7 ml/min*kg vs. 49.7 ml/min*kg ± 6.8; P = 0.002) (Fig. 1). At maximum physical exercise VO_2max was 4306 ± 594 ml/min and relative VO_2max was 54.7 ± 6.5 ml/min*kg. Calculated fitness index was 178 ± 20 ml/min*kg.

No correlation with VO_2max or relative VO_2max was shown for GLS at rest, after CPET, and ΔGLS. However, GWI after CPET and relative VO_2max (r = 0.459; P = 0.048) as well as ΔGWI and relative VO_2max (r = 0.592; P = 0.008) showed moderate correlations (Table 4).

Intra- and interobserver variabilities

Intraobserver variabilities of GLS measurements were 2.16% at rest (P = 0.638) and 2.61% after CPET (P = 0.491). Interobserver variabilities of GLS measurements were 3.91% at rest (P = 0.337) and 4.23% after CPET (P = 0.312). Intra- and interobserver variabilities for LV volumes, LVEF, CI, and sPAP measurements were < 5% without reaching statistical significance.

The main findings of the present study are:

(1) GLS and GWI did not differ significantly before and after semi-recumbent ergometer and treadmill testing. (2) There was no significant correlation between GLS and (relative) VO_2max, but (3) there were significant correlations between ΔGWI and relative VO_2max in semi-recumbent ergometer and treadmill testing.

Baseline echocardiographic parameters

Changes of conventional echocardiographic parameters after CPET (e.g. LV volumes), were in line with the results of previous studies and have already been described²⁹. Both, low intra- and interobserver variabilities highlight the quality of data acquisition as well as the robustness of conventional but also deformation parameters, e.g. GLS⁷.

Impact of maximum exercise on global longitudinal strain

The impact of pre- and afterload conditions on LV systolic function has already been described³⁰. In general data analyzing the impact of physical stress on LV deformation are scarce and the results of previous studies are highly heterogeneous. Some previous clinical studies have proven a significant impact of pre- and afterload conditions on GLS^31,32,33,34. Nevertheless, GLS was not able to predict load-independent contractility in a porcine model³⁵. The impact of different CPET methods on global longitudinal strain in competitive athletes has not been described before.

Liang et al. assessed GLS in 15 swimming athletes before and after high-intensity exercise, where GLS was significantly lower after high-intensity exercise³⁶. The decrease of GLS was explained by negative effects on myocardial cells based on anaerobic glycolysis due to ischemia, hypoxia, and the formation of lactic acid with a reduction of myocardial contraction force and consequently, a decrease of LV myocardial contractile function³⁷. These results were in contrast to Gruca et al., where GLS was significantly increased in 69% of 111 male elite basketball players in the first minute after maximum physical exertion due to treadmill testing³⁸. The increase of GLS at peak exercise was explained by a lower baseline and peak HR, which could not be observed in our study. Neither athletes on semi-recumbent ergometer and treadmill showed significant correlations with HR or differences of mean GLS before and after CPET. Mean GLS was slightly lower after both, semi-recumbent ergometer and treadmill testing, but did not reach statistical significance. This finding can be explained by higher blood pressure after CPET and consequently higher afterload conditions which was already described in an experimental pig model of aortic banding³⁴. It needs to be considered that athletes of different sports are exposed to different forms of physical exercise, and these in turn also have different effects on the cardiovascular system especially on LV remodeling. However, the results of our study are consistent with those of Santoro et al. where GLS was assessed in 27 male water polo players and did not differ significantly before and after 6 repetitions of 100-m freestyle swimming sets³⁹.

Whereas Gianturco et al. demonstrated a very strong correlation between VO_2max and GLS in a cohort of 20 soccer referees and proposed GLS as a specific parameter to assess football referees performance⁴⁰, there was no significant correlation between VO_2max and GLS in our study. The lack of correlation between GLS and VO2_max does not allow us to draw conclusions about cardiopulmonary exercise capacity based on GLS values in male handball and football players. The discrepancy between the results of Gianturco et al. and our study could be most likely explained by different training conditions.

Impact of maximum exercise on global myocardial work index

Global myocardial work index has proven to be a reliable method for assessing LV function and is capable of detecting subtle myocardial changes. In noninvasive estimation of LV pressure, GWI based on the pressure strain loop incorporates the current afterload condition and is able to assess LV mechanical function and the myocardial oxygen consumption⁴¹.

Sengupta et al. assessed GWI in 24 recreational athletes before as well as up to a maximum of 2 and 72 hours after completing a marathon and found either a decrease in GWI or no change in GWI⁴². A decrease of GWI was attributed to differences in HR and lower LV filling volumes. According to the results of the present study, both aspects could also be observed in professional athletes immediately after CPET, because TTE was performed 5 minutes after CPET in the present study. GWI has proved to be afterload-independent permitting a more comprehensive assessment of LV systolic function¹¹, which is beneficial in athletes exposed to different physical exercise. Although systolic blood pressure as a surrogate parameter for afterload conditions was increased in all athletes after CPET. In this study, irrespective of the CPET method, mean GWI did not differ before and after CPET and an individual increase or decrease in GWI was observed in each athlete. This finding lead to the assumption that LV deformation is significantly affected by maximum exercise, whereas the method of exercise testing, semi-recumbent ergometer or treadmill, does not make a difference.

Correlation between VO_2max and GWI

Tokodi et al. described a moderate correlation between CPET-derived relative VO_2max and GWI at rest in a cohort of 20 elite swimmers⁴³, which was not observed in our study. However, there was a significant correlation between relative VO_2max and ΔGWI in both cohorts. This observation can be explained by the fact that well-trained athletes with higher fitness levels show a pronounced increase in GWI after CPET according to their relative VO_2max, whereas a decrease in GWI after CPET seems to be associated with a lower cardiopulmonary exercise capacity. It can be assumed that ΔGWI can be considered as a surrogate parameter to assess the current training condition of athletes.

Limitations

The number of subjects was limited by the size of the teams in the German handball and football Bundesliga studied at Leipzig University Hospital. However, these highly selected young and healthy competitive athletes highlight the exceptionality of the present cohort. Therefore, the results are not directly applicable to patients with cardiovascular disease. Both semi-recumbent ergometer and treadmill testing could not be performed in all athletes due to their limited time schedule for testing. The modality of incremental cardiopulmonary exercise test was predetermined by the respective medical team leader.

VO2_max is considered an important indicator of athlete's training condition and maximum performance capacity. In the present study we confirmed that maximum exercise has a significant effect on LV deformation, irrespective of the exercise method. The impact of maximum physical exercise on LV deformation did not differ between semi-recumbent ergometer and treadmill testing. Further, we were able to demonstrate a significant correlation between ΔGWI and VO2_max directly after CPET, so that the current training condition or maximum performance capacity of an athlete might also be estimated by a single modern imaging parameter instead of only VO2_max. Further studies are needed to clarify whether athletes who demonstrate a decrease in GWI and a lower VO2_max after CPET actually have a higher performance potential and thus their maximal performance capacity can be further improved. If so, GWI could be used as a modern imaging parameter to characterize the athletes’ maximum performance capacity, which would considerably enrich and simplify individual performance diagnostics.

Ethical Approval

All athletes provided informed consent to participate and publish after full explanation of the purpose and order of all procedures. The study was conducted in accordance with the Declaration of Helsinki and was approved by the ethical committee of the University of Leipzig (073/18-ek).

Competing interests

The authors have nothing to declare.

Authors' contributions

A.H., J.K. and S.F. designed the study. A.H. and S.S. performed all the echocardiographic examinations. J.K. and S.S. analysed the data. A.K. performed the statistics. J.K. and S.S. wrote the manuscript. The rest of the authors provided critical feedback and helped shape the research, analysis and manuscript.

Funding

No funding

Availability of data and materials

The authors confirm that the data supporting the findings of this study are available within the article.

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You are reading this latest preprint version

Effects of different exercise testing methods on left ventricular deformation and its correlation with cardiopulmonary exercise capacity in competitive athletes – semi-recumbent ergometer vs. treadmill testing

Status:

Version 1

Abstract

Background

Methods

Results

Conclusion

Figures

Introduction

Methods

Study population and study design

Incremental cardiopulmonary exercise test for handball players

Incremental cardiopulmonary exercise test for football players

Transthoracic echocardiography

Statistical analysis

Results

Semi-recumbent ergometer

Treadmill testing

Intra- and interobserver variabilities

Discussion

The main findings of the present study are:

Baseline echocardiographic parameters

Impact of maximum exercise on global longitudinal strain

Impact of maximum exercise on global myocardial work index

Correlation between VO_2max and GWI

Limitations

Conclusion

Declarations

References

Additional Declarations

Status:

Version 1

Effects of different exercise testing methods on left ventricular deformation and its correlation with cardiopulmonary exercise capacity in competitive athletes – semi-recumbent ergometer vs. treadmill testing

Status:

Version 1

Abstract

Background

Methods

Results

Conclusion

Figures

Introduction

Methods

Study population and study design

Incremental cardiopulmonary exercise test for handball players

Incremental cardiopulmonary exercise test for football players

Transthoracic echocardiography

Statistical analysis

Results

Semi-recumbent ergometer

Treadmill testing

Intra- and interobserver variabilities

Discussion

The main findings of the present study are:

Baseline echocardiographic parameters

Impact of maximum exercise on global longitudinal strain

Impact of maximum exercise on global myocardial work index

Correlation between VO2max and GWI

Limitations

Conclusion

Declarations

References

Additional Declarations

Status:

Version 1

Correlation between VO_2max and GWI