Cardiac profiles of national-class race walkers

Concentric myocardial hypertrophy after one year of increased training volume in experienced distance runners

OBJECTIVES

As evidence on the predominant type of cardiac hypertrophy due to endurance running training is inconsistent, the aim of this study was to investigate the effect of increased training volume on echocardiographic variables of distance runners.

METHODS

Twenty three adult, experienced, male distance runners underwent standard two dimensionally guided M mode and Doppler echocardiography before and after a one year period during which they were randomly allocated to either control (n = 11) or intervention (n = 12) groups. The intervention group increased their training volume from (mean (SD)) 8.0 (3.0) to 12.5 (3.9) hours/week without increasing the intensity, and the controls changed neither training parameter.

RESULTS

In the intervention group, training induced an increase in left ventricular (LV) mass (from 240.4 (53.8) to 279.5 (60.6) g, p<0.001) and LV mass index (from 126.7 (28.2) to 147.6 (32.3) g/m2, p<0.001) mainly due to an increase in end diastolic interventricular septum (from 10.4 (1.8) to 11.5 (1.7) mm, p<0.01) and LV posterior wall thickness (from 10.4 (1.6) to 11.5 (1.6) mm, p<0.001). No significant changes in LV internal diameter or measured indices of LV function occurred (p>0.05). The sum of the right ventricular diameter and wall thickness was greater after the increased volume training (p<0.05). None of the variables changed significantly in the control group (p>0.05).

CONCLUSIONS

In experienced, subelite distance runners, further increasing the training volume results in concentric cardiac hypertrophy.

Physiology of professional road cycling

Professional road cycling is an extreme endurance sport. Approximately 30000 to 35000 km are cycled each year in training and competition and some races, such as the Tour de France last 21 days (approximately 100 hours of competition) during which professional cyclists (PC) must cover >3500 km. In some phases of such a demanding sport, on the other hand, exercise intensity is surprisingly high, since PC must complete prolonged periods of exercise (i.e. time trials, high mountain ascents) at high percentages (approximately 90%) of maximal oxygen uptake (VO2max) [above the anaerobic threshold (AT)]. Although numerous studies have analysed the physiological responses of elite, amateur level road cyclists during the last 2 decades, their findings might not be directly extrapolated to professional cycling. Several studies have recently shown that PC exhibit some remarkable physiological responses and adaptations such as: an efficient respiratory system (i.e. lack of 'tachypnoeic shift' at high exercise intensities); a considerable reliance on fat metabolism even at high power outputs; or several neuromuscular adaptations (i.e. a great resistance to fatigue of slow motor units). This article extensively reviews the different responses and adaptations (cardiopulmonary system, metabolism, neuromuscular factors or endocrine system) to this sport. A special emphasis is placed on the evaluation of performance both in the laboratory (i.e. the controversial Conconi test, distinction between climbing and time trial ability, etc.) and during actual competitions such as the Tour de France.

Heart dimensions may influence the occurrence of the heart rate deflection point in highly trained cyclists

OBJECTIVES

To determine whether the heart rate (HR) response to exercise in 21 highly trained cyclists (mean (SD) age 25 (3) years) was related to their heart dimensions.

METHODS

Before performing an incremental exercise test involving a ramp protocol with workload increases of 25 W/min, each subject underwent echocardiographic evaluation of the following variables: left ventricular end diastolic internal diameter (LVIDd), left ventricular posterior wall thickness at end diastole (LVPWTd), interventricular septal wall thickness at end diastole (IVSTd), left ventricular mass index (LVMI), left atrial dimension (LAD), longitudinal left atrial (LLAD) and right atrial (LRAD) dimensions, and the ratio of early to late (E/A) diastolic flow velocity.

RESULTS

The HR response showed a deflection point (HRd) at about 85% VO2MAX in 66.7% of subjects (D group; n = 14) and was linear in 33.3% (NoD group; n = 7). Several echocardiographic variables (LVMI, LAD, LLAD, LRAD) indicative of heart dimensions were similar in each group. However, mean LPWTd (p<0.01) and IVSTd (p<0.05) values were significantly higher in the D group. Finally, no significant difference between groups was found with respect to the E/A.

CONCLUSIONS

The HR response is curvilinear during incremental exercise in a considerable number of highly trained endurance athletes-that is, top level cyclists. The departure of HR increase from linearity may predominantly occur in athletes with thicker heart walls.

Comparison of left ventricular function using isometric exercise Doppler echocardiography in competitive runners and weightlifters versus sedentary individuals

It is unclear whether cardiovascular responses to heavy isometric exercise are changed by intensive training. We evaluated the effects of this type of exercise on left ventricular (LV) function in athletes engaged in static and dynamic sport, compared with sedentary persons, and looked for peculiarities in static athletes' responses that might reflect adaptive mechanisms to their specific activity. The study population comprised 45 men (age 24 +/- 5 years): 29 dynamic and 16 static athletes (runners and weightlifters, respectively). The control group consisted of 20 age and gender-matched healthy sedentary persons. All performed 50% of maximal voluntary contraction on a whole-body isometric exercise device for 2 minutes. Echocardiographic calculations were determined at rest and exercise. Upon exercise, stroke volume, cardiac output, end-diastolic volume, and ejection fraction increased significantly in athletes, while end-systolic volume and systemic vascular resistance decreased. In sedentary persons, stroke volume and resistance remained unchanged, cardiac output and LV volumes increased, and ejection fraction decreased from 67 +/- 5% to 60 +/- 5% (p <0.01 compared with rest; p <0.0001 compared with athletes). Whereas peak flow velocity decreased from 103 +/- 10 to 81 +/- 6 cm/s in sedentary persons, it increased from 112 +/- 9 to 126 +/- 8 cm/s in the static group and from 120 +/-3 to 126 +/- 9 cm/s in the dynamic athletes (p <0.0001 compared with the sedentary group). Mean acceleration decreased in the sedentary group, remained unchanged among the dynamic athletes, and increased among the static athletes. We conclude that cardiovascular responses to heavy isometric exercise are modified by intensive training. Athletes, taken as a group, react differently and adapt better than sedentary individuals. Moreover, among them, those involved in static sport show an improved cardiovascular adaptation to this type of exercise.