Long-term ultra-marathon running and arterial compliance.

UNLABELLED: Recent reports that habitual marathon runners demonstrate higher levels of stiffness and cardiovascular risk factors have been of great interest to the medical and scientific community. Ultra-marathon running, that is any distance >42.2 km, is increasing in popularity; however, little is known regarding the physiological effects of the sport's unique training and racing practices on vascular health. OBJECTIVES: To characterize and compare the arterial compliance of male long-term (>5 years) ultra-marathoners with recreationally active controls, and examine the associations of training related practices with systemic arterial compliance. DESIGN: We employed a case-control comparison design using long-term habitual ultra-marathon runners (n=18) and an age matched cohort of normative recreationally active males. METHODS: Arterial compliance was measured at rest using radial applanation tonometry (CR-2000, HDI) for diastolic pulse contour analysis. Compliance was compared with normative data, participant characteristics, and associated exercise parameters. RESULTS: In representative ultra-endurance runners, large artery compliance of long-term participants was reduced compared with physically active age-matched controls (p=0.03) and is related to select training variables. Specifically, in a representative subset for whom we obtained detailed training data, decreased compliance was related to longer typical running distance per training session (r=-0.72, p=0.03); however, more broad definitions of frequency, intensity, and duration revealed no association for the runners as a whole. CONCLUSIONS: Given the known associations of arterial stiffness with future cardiovascular events, ultra-endurance runners may be at an increased risk of a cardiovascular event compared with their normally active counterparts.

Aortic distensibility is reduced during intense lower body negative pressure and is related to low frequency power of systolic blood pressure.

As sympathetic activity approximately doubles during intense lower body negative pressure (LBNP) of -60 mmHg or greater, we examined the relationship between surrogate markers of sympathetic activation and central arterial distensibility during severe LBNP. Eight participants were exposed to progressive 8-min stages of LBNP of increasing intensity (-20, -40, -60, and -80 mmHg), while recording carotid-femoral pulse wave velocity (cPWV), stroke volume (SV), heart rate, and beat-by-beat blood pressure. The spectral power of low frequency oscillations in SBP (SBP(LF)) was used as a surrogate indicator of sympathetically modulated vasomotor modulation. Total arterial compliance (C) was calculated as C = SV/pulse pressure. Both cPWV and C were compared between baseline, 50 % of the maximally tolerated LBNP stage (LBNP(50)), and the maximum fully tolerated stage of LBNP (LBNP(max)). No change in mean arterial pressure (MAP) occurred over LBNP. An increase in cPWV (6.5 ± 2.2; 7.2 ± 1.4; 9.0 ± 2.5 m/s; P = 0.004) occurred during LBNP(max). Over progressive LBNP, SBP(LF) increased (8.5 ± 4.6; 9.3 ± 5.8; 16.1 ± 12.9 mmHg(2); P = 0.04) and C decreased significantly (18.3 ± 6.8; 14.3 ± 4.1; 11.6 ± 4.8 ml/mmHg × 10; P = 0.03). The mean correlation (r) between cPWV and SBP(LF) was 0.9 ± 0.03 (95 % CI 0.79-0.99). Severe LBNP increased central stiffness and reduced total arterial compliance. It appears that increased sympathetic vasomotor tone during LBNP is associated with reduced aortic distensibility in the absence of changes in MAP.

Physiological demands of downhill mountain biking.

Mountain biking is a popular recreational pursuit and the physiological demands of cross-country style riding have been well documented. However, little is known regarding the growing discipline of gravity-assisted downhill cycling. We characterised the physiological demands of downhill mountain biking under typical riding conditions. Riding oxygen consumption (VO(2)) and heart rate (HR) were measured on 11 male and eight female experienced downhill cyclists and compared with data during a standardised incremental to maximum (VO(2max)) exercise test. The mean VO(2) while riding was 23.1 ± 6.9 ml · kg(-1) · min(-1) or 52 ± 14% of VO(2max) with corresponding heart rates of 146 ± 11 bpm (80 ± 6% HRmax). Over 65% of the ride was in a zone at or above an intensity level associated with improvements in health-related fitness. However, the participants' heart rates and ratings of perceived exertion were artificially inflated in comparison with the actual metabolic demands of the downhill ride. Substantial muscular fatigue was evident in grip strength, which decreased 5.4 ± 9.4 kg (5.5 ± 11.2%, P = 0.03) post-ride. Participation in downhill mountain biking is associated with significant physiological demands, which are in a range associated with beneficial effects on health-related fitness.

A segmental evaluation of arterial stiffness before and after prolonged strenuous exercise.

We aimed to investigate the effects of a single session of prolonged strenuous exercise (PSE) on arterial stiffness by measuring pulse wave velocity (PWV) before and after competition in an ultramarathon. A total of 20 routine ultramarathon competitors (UM) completed baseline and postrace evaluation of central PWV (cPWV), upper-limb PWV (uPWV), and lower-limb PWV (lPWV) using carotid artery - femoral artery, carotid artery - finger, and femoral artery - toe segments, respectively. Fourteen additional age- and gender-matched normally active participants (NA) took part in the identical baseline evaluation but did not participate in the race. Average ultramarathon completion time was 30 h 47 min. Mean arterial blood pressure was reduced after exercise (before exercise (pre), 92 ± 7 mm Hg; after exercise (post), 84 ± 7 mm Hg; P < 0.001), whereas heart rate was increased (pre, 57 ± 10 beats·min(-1); post, 73 ± 12 beats·min(-1); P < 0.001). Also, lPWV (pre, 11.8 ± 3.6 m·s(-1); post, 9.6 ± 2.6 m·s(-1); P < 0.05) and uPWV (pre, 5.0 ± 0.53 m·s(-1); post, 4.4 ± 0.8 m·s(-1); P < 0.01) were reduced after exercise. No change in cPWV occurred (pre, 4.1 ± 0.8 m·s(-1); post, 3.9 ± 1.3 m·s(-1); P = 0.55). At baseline, the NA group had significantly increased cPWV in comparison with the UM group (UM, 4.1 ± 0.8 m·s(-1); NA, 7.4 ± 1.3 m·s(-1); P < 0.001). Acute participation in PSE influenced peripheral but not central arterial stiffness. Those who routinely participate in PSE have reduced central arterial stiffness as compared with normally active, age- and gender-matched controls.

Left ventricular twisting mechanics and exercise in healthy individuals: a systematic review.

The aim of this study was to review systematically the effects of exercise on left ventricular (LV) twisting mechanics in healthy individuals. Literature searches were conducted in electronic databases for articles reporting measures of LV twisting mechanics in healthy individuals before and during/after exercise. Upon review, 18 articles were analyzed. Studies were separated by exercise type into the following four categories to allow for detailed comparisons: submaximal, prolonged endurance, maximal, and chronic endurance. Despite an overall methodological quality of low to moderate and within-group variations in exercise intensity, duration, and subject characteristics, important trends in the literature emerged. Most important, the coupling of LV systolic twisting and diastolic untwisting was present in all exercise types, as both were either improved or impaired concomitantly, highlighting the linkage between systole and diastole provided through LV twist. In addition, trends regarding the effects of age, training status, and cardiac loading also became apparent within different exercise types. Furthermore, a potential dose-response relationship between exercise duration and the degree of impairment to LV twisting mechanics was found. Although some disagreement existed in results, the observed trends provide important directions for future research. Future investigations should be of higher methodological quality and should include consistent exercise protocols and subject populations in order to minimize the variability between investigations.