Karen M. Birch

Changes in maximal voluntary force of human adductor pollicis muscle during the menstrual cycle.

1. Muscle strength of the adductor pollicis (AP) was studied throughout the menstrual cycle to determine whether any variation in force is similar to the known cyclical changes in ovarian hormones. Three groups of young women were studied: trained regularly menstruating athletes (trained), untrained regularly menstruating (untrained) and trained oral contraceptive pill users (OCU). In addition a group of untrained young men was studied as controls. 2. Maximum voluntary force (MVF) of AP was measured over a maximum period of 6 months. Ovulation was detected by luteinizing hormone measurements or change in basal body temperature. There was a significant increase in MVF (about 10%) during the follicular phase of the menstrual cycle when oestrogen levels are rising, in both the trained and untrained groups. This was followed by a similar in MVF around the time of ovulation. Neither the OCU nor the male subjects showed cyclical changes in MVF.

Dilatation and Dysfunction of the Right Ventricle Immediately After Ultraendurance Exercise Exploratory Insights From Conventional Two-Dimensional and Speckle Tracking Echocardiography

Background— Running an ultramarathon has been shown to have a transient negative effect on right ventricular (RV) and left ventricular (LV) function. Additionally, recent findings suggested that ultraendurance athletes may be more at risk of developing a RV cardiomyopathy. The standard echocardiographic assessment of RV function is problematic; however, the introduction of ultrasonic speckle tracking technology has the potential to yield a comprehensive evaluation of RV longitudinal function, providing new insights into this phenomenon. Thus, the primary aim of this exploratory study was to evaluate comprehensively RV structure and function after a 161-km ultramarathon and establish whether changes in the RV are associated with alterations in LV function. Methods and Results— Myocardial speckle tracking echocardiograms of the RV and LV were obtained before and immediately after a 161-km ultramarathon in 16 healthy adults. Standard echocardiography was used to determine RV size and function and LV eccentricity index. Speckle tracking was used to determine the temporal evaluation of indices of RV and LV function. RV size was significantly increased postrace (RV outflow, 32 to 35 mm, P =0.002; RV inflow, 42 to 45 mm, P =0.027) with an increase in LV eccentricity index (1.03 to 1.13, P =0.006). RV strain (e) was significantly reduced postrace (−27% to −24%, P =0.004), but there was no change in the rates of e. Peak e in all planes of LV motion were reduced postrace (longitudinal, −18.3 to −16.3%, P =0.012; circumferential, −20.2% to −15.7%, P =0.001; radial, 53.4% to 40.3%, P =0.009). Changes in RV size and function correlated with diastolic strain rates in the LV. Conclusions— This exploratory study demonstrates RV dilatation and reduction in function after an ultramarathon. Further research is warranted to elucidate the mechanisms responsible for these findings. It is not clear what clinical impact might result from consecutive bouts of postexercise RV dysfunction.Background— Running an ultramarathon has been shown to have a transient negative effect on right ventricular (RV) and left ventricular (LV) function. Additionally, recent findings suggested that ultraendurance athletes may be more at risk of developing a RV cardiomyopathy. The standard echocardiographic assessment of RV function is problematic; however, the introduction of ultrasonic speckle tracking technology has the potential to yield a comprehensive evaluation of RV longitudinal function, providing new insights into this phenomenon. Thus, the primary aim of this exploratory study was to evaluate comprehensively RV structure and function after a 161-km ultramarathon and establish whether changes in the RV are associated with alterations in LV function. Methods and Results— Myocardial speckle tracking echocardiograms of the RV and LV were obtained before and immediately after a 161-km ultramarathon in 16 healthy adults. Standard echocardiography was used to determine RV size and function and LV eccentricity index. Speckle tracking was used to determine the temporal evaluation of indices of RV and LV function. RV size was significantly increased postrace (RV outflow, 32 to 35 mm, P=0.002; RV inflow, 42 to 45 mm, P=0.027) with an increase in LV eccentricity index (1.03 to 1.13, P=0.006). RV strain (&egr;) was significantly reduced postrace (−27% to −24%, P=0.004), but there was no change in the rates of &egr;. Peak &egr; in all planes of LV motion were reduced postrace (longitudinal, −18.3 to −16.3%, P=0.012; circumferential, −20.2% to −15.7%, P=0.001; radial, 53.4% to 40.3%, P=0.009). Changes in RV size and function correlated with diastolic strain rates in the LV. Conclusions— This exploratory study demonstrates RV dilatation and reduction in function after an ultramarathon. Further research is warranted to elucidate the mechanisms responsible for these findings. It is not clear what clinical impact might result from consecutive bouts of postexercise RV dysfunction.

Female athlete triad

The “female athlete triad” has long been recognised as a syndrome that has the potential to affect female athletes and consists of three inter-related disorders: The potential impact of each of, and the combination of, these disorders is detrimental to performance and to health. Certainly, the increased risk of infertility, stress fractures, eating disorders, and osteoporosis in later life is a high price to pay for involvement in an essentially healthy activity. This is especially true, as many of these factors can be prevented with careful management. ![][1] The female athlete triad can affect performance and health but can be prevented with good management The three corners of the triad are inter-related through psychological and physiological mechanisms. The psychological pressures to perform to an optimal standard, and thus often a perceived requirement to maintain a low body mass, result in a high volume of training. The high volume of training and low energy intake, in addition to stress hormones produced by psychological stress, may lead to a physiological alteration in the endocrinological control of the menstrual cycle, which may ultimately lead to the athlete becoming amenorrhoeic (loss of cycle after menarche). The consequence of being amenorrhoeic through dysfunction of the hypothalamus and pituitary is a decreased production of oestrogen. This hormone has a huge role in maintaining adequate bone mineral density, and a hypo-oestrogenic state (low oestrogen) thus is associated with low bone mineral density and an increased risk of osteoporosis. The normal regular, healthy menstrual cycle (eumenorrhoea) is about 26-35 days, is controlled by the hypothalamus and pituitary glands, and is divided simplistically into two phases by the occurrence mid-cycle of ovulation. The first half of the cycle is the follicular phase and the second half the luteal phase. The follicular phase is characterised by … [1]: /embed/graphic-1.gif

Exercise-Induced Cardiac Fatigue—A Review of the Echocardiographic Literature

There is growing evidence to support the suggestion that prolonged strenuous exercise has a negative impact on left and right ventricular function during recovery. The main body of evidence covers a 20‐year time window with many studies using transthoracic echocardiography to quantify cardiac function. Although studies have addressed different exercise modes and durations most work has been “field” based. During this time period echocardiographic instrumentation and techniques have evolved significantly and their application in the assessment of prolonged exercise has developed in tandem. The primary objective of this article is to provide reflective insight into the phenomenon of “exercise induced cardiac fatigue” by critically evaluating available literature in different competitive field studies or lab‐based settings. We achieve this objective by introducing the empirical evidence in relation to echocardiographic modalities employed in developmental order including standard 2D, Doppler, tissue Doppler derived myocardial velocity and strain and myocardial speckle tracking echocardiography and by looking at different modes and duration of exercise. The insights provided by data based on each technique are critically reviewed, contradictory findings are explored and the potential for further work is identified. Furthermore the clinical implications and proposed mechanisms of “exercise‐induced cardiac fatigue” are also explored. (Echocardiography 2010;27:1130‐1140)

Intraobserver Reliability of Two-Dimensional Ultrasound Derived Strain Imaging in the Assessment of the Left Ventricle, Right Ventricle, and Left Atrium of Healthy Human Hearts

Aims: To determine the intraobserver reproducibility of peak and temporal values for myocardial strain (ɛ) and strain rate (SR) using a speckle tracking technique in the left ventricle (LV), right ventricle (RV), and left atrium (LA). Methods and Results: Myocardial speckle tracking echocardiograms of the LV, RV, and LA were obtained on 20 healthy adults to provide indices of longitudinal, radial, circumferential ɛ, and SR as well as LV rotation and twist. Each participant had two separate acquisitions approximately 30 minutes apart. No systematic bias was present in ɛ data. LV ɛ across all planes provided “good” to “very good” intraclass correlation coefficient (ICC) values (0.714–0.807), however radial ɛ was inferior in terms of coefficients of variation (CoV) (19%). SR data were more variable than ɛ with LV radial SR performing least favorably. RV and LA ɛ demonstrated excellent reproducibility (ICCs of 0.834, 0.959, and CoVs of 7% and 6%, respectively). RV and LA SR were again more variable but generally acceptable ICC > 0.6 and CoV < 15%. Peak basal and apical rotation demonstrated quite high variability while derived torsion had low variability and excellent agreement (ICC = 0.940, CoV = 10%). Time‐to‐peak values demonstrated acceptable agreement with the exception of systolic SR from all chambers. Conclusion: Good reproducibility was obtained for peak ɛ indices although radial ɛ performs less favorably. Intraobserver variation of peak ɛ appears superior to values obtained for peak SR. Time‐to‐peak values demonstrate very good intraobserver reproducibility across all planes of contraction with exception of (time‐to‐peak) systolic strain rate (SRS).

Human Exercise-Induced Circulating Progenitor Cell Mobilization Is Nitric Oxide-Dependent and Is Blunted in South Asian Men

Objective—Circulating progenitor cells (CPC) have emerged as potential mediators of vascular repair. In experimental models, CPC mobilization is critically dependent on nitric oxide (NO). South Asian ethnicity is associated with reduced CPC. We assessed CPC mobilization in response to exercise in Asian men and examined the role of NO in CPC mobilization per se. Methods and Results—In 15 healthy, white European men and 15 matched South Asian men, CPC mobilization was assessed during moderate-intensity exercise. Brachial artery flow-mediated vasodilatation was used to assess NO bioavailability. To determine the role of NO in CPC mobilization, identical exercise studies were performed during intravenous separate infusions of saline, the NO synthase inhibitor l-NMMA, and norepinephrine. Flow-mediated vasodilatation (5.8%±0.4% vs 7.9%±0.5%; P=0.002) and CPC mobilization (CD34+/KDR+ 53.2% vs 85.4%; P=0.001; CD133+/CD34+/KDR+ 48.4% vs 73.9%; P=0.05; and CD34+/CD45− 49.3% vs 78.4; P=0.006) was blunted in the South Asian group. CPC mobilization correlated with flow-mediated vasodilatation and l-NMMA significantly reduced exercise-induced CPC mobilization (CD34+/KDR+ −3.3% vs 68.4%; CD133+/CD34+/KDR+ 0.7% vs 71.4%; and CD34+/CD45− −30.5% vs 77.8%; all P<0.001). Conclusion—In humans, NO is critical for CPC mobilization in response to exercise. Reduced NO bioavailability may contribute to imbalance between vascular damage and repair mechanisms in South Asian men.

Heavy and moderate interval exercise training alters low-flow-mediated constriction but does not increase circulating progenitor cells in healthy humans

Moderate‐intensity endurance exercise training improves vascular endothelial vasomotor function; however, the impact of high‐intensity exercise training has been equivocal. Thus, the effect of the physiological stress of the exercise remains poorly understood. Furthermore, enhanced vascular repair mediated by circulating progenitor cells may also be improved. To address whether the physiological stress of exercise training is an important factor contributing to these adaptations, 20 healthy participants trained for 6 weeks. Training involved either moderate (MSIT; n= 9) or heavy metabolic stress (HSIT; n= 11) interval exercise training programmes matched for total work and duration of exercise. Before and after training, flow‐mediated dilatation, low‐flow‐mediated constriction and total vessel reactivity were measured at the brachial artery using Doppler ultrasound. Circulating progenitor cells (CD34+, CD133+ and CD309/KDR+) were measured by flow cytometry (means ± SD). Relative (MSIT pre‐ 5.5 ± 3.4 versus post‐training 6.6 ± 2.5%; HSIT pre‐ 6.6 ± 4.1 versus post‐training 7.0 ± 3.4%, P= 0.33) and normalized (P= 0.16) flow‐mediated dilatation did not increase with either training programme. However, low‐flow‐mediated constriction was greater after training in both groups (MSIT pre‐ −0.5 ± 3.2 versus post‐training −1.9 ± 3.1%; HSIT pre‐ −1.0 ± 1.7 versus post‐training −2.9 ± 3.0%, P= 0.04) and contributed to greater total vessel reactivity (MSIT pre‐ 7.4 ± 3.3 versus post‐training 10.1 ± 3.7%; HSIT pre‐ 10.9 ± 5.9 versus post‐training 12.7 ± 6.2%, P= 0.01). Peak reactive hyperaemia and the area under the shear rate curve were not different between groups, either before or after training. Although circulating progenitor cell numbers increased following heavy‐intensity interval exercise training, variability was great amongst participants [MSIT pre‐ 16 ± 18 versus post‐training 14 ± 12 cells (ml whole blood)−1; HSIT pre‐ 8 ± 6 versus post‐training 19 ± 23 cells (ml whole blood)−1, P= 0.50]. Overall, vasoconstrictor function may be augmented by moderate‐ and heavy‐intensity interval exercise training in young adults. However, circulating progenitor cell numbers were not increased, suggesting that these cells are not likely to be upregulated as a result of training.

Interpretation of two-dimensional and tissue Doppler-derived strain ( ε ) and strain rate data: is there a need to normalize for individual variability in left ventricular morphology?

AIMS This study examined the relationships between myocardial strain (epsilon) and strain rate (SR) data, derived from both two-dimensional (2D) speckle tracking and tissue Doppler imaging (TDI), and indices of left ventricular (LV) morphology to assess size-(in)dependence of these functional parameters. METHODS AND RESULTS 2D speckle tracking and TDI echocardiograms were performed in 79 healthy adult male volunteers (age range: 22-76 years). 2D speckle tracking allowed the determination of myocardial epsilon and peak systolic and early diastolic SR in radial, circumferential, and longitudinal planes, whereas TDI provided longitudinal epsilon only. Mean circumferential and radial epsilon and SR were calculated from data collected at six basal myocardial regions, whereas mean longitudinal epsilon and SR derived from both 2D speckle tracking and TDI were calculated from the basal septum and basal lateral walls. Standard 2D echocardiography allowed the assessment of LV morphology including LV length, LV end-diastolic volume, LV end-diastolic diameter, mean wall thickness, and LV mass. The association of myocardial epsilon and SR data with relevant LV morphology indices was determined by adoption of the general, non-linear allometric model (y= ax(b)). The b exponent +/- 95% confidence intervals were reported. The relationships between the measures of LV morphology and myocardial epsilon and SR were highly variable and generally weak. Only two relationships displayed at least a moderate effect size (r > or = 0.30): (i) 2D circumferential peak systolic SR and LV end-diastolic dimension (b = -0.92; -1.35 to 0.5, r = 0.44) and (ii) TDI longitudinal peak systolic SR and LV length (b = -1.39; -2.11 to -0.66, r = 0.41). CONCLUSION The empirical relationships derived in this cohort do not support the need to scale myocardial epsilon and SR derived from 2D speckle or TDI for any index of LV morphology.

Repeatability of measurement in determining stature in sitting and standing postures

The aim of this study was to determine the effect of sitting and standing postures on the repeatability of a stadiometer designed to detect small variations in spinal length. Two groups of ten healthy subjects, with no previous or known history of back problems, participated in this study. One group was measured in the standing posture, while the other group was measured in a sitting posture. All subjects gave informed consent to participate in this study. Subjects had a set of landmarks defining the spinal contour marked on their backs and then stood in the stadiometer for three series of ten measurements to be performed. At the end of each measurement, the subjects were requested to move away from and then be repositioned in the stadiometer. Subjects improved the repeatability across the measurement series. At the end of the second measurement series, all subjects presented mean standard deviations of 0.43±0.08 mm (range 0.300.50 mm) in the standing posture. In the sitting posture, deviations of less than 0.05 mm were obtained only at the end of the third measurement series (0.48±0.08 mm; range 0.340.62 mm), suggesting that this posture required three measurement series before repeatable measurements could be assured rather than two in the standing posture.

Left ventricular morphology and function in endurance-trained female athletes.

In this study, we investigated resting left ventricular dimensions and function in trained female rowers, canoeists and cyclists. In male populations, such athletes have demonstrated the largest left ventricular wall thicknesses and cavity dimensions. Echocardiograms were analysed from 24 athletes (rowers and canoeists, n = 12; cyclists, n = 12) and 21 age-matched controls to measure left ventricular end-diastolic dimension and volume, and septal (ST) and posterior wall (PWT) thicknesses. Left ventricular mass was calculated from M-mode data. Systolic and diastolic function were calculated from M-mode and Doppler echocardiography, respectively. Height, body mass, body surface area and fat-free mass were determined anthropometrically. The athletes were well matched with the controls for all anthropometric variables except fat-free mass (rowers and canoeists 49.7+/-3.6 kg, cyclists 48.0+/-3.8 kg, controls 45.0+/-5.4 kg; P < 0.05). The left ventricular end-diastolic dimension, mass and volume, and septal and posterior wall thicknesses, were all significantly greater in the athletes than the controls (P < 0.05). These differences persisted (except for left ventricular end-diastolic dimension) even after allometric adjustment for group differences in fat-free mass. Stroke volume was larger (rowers and canoeists 102+/-13 ml, cyclists 103+/-16 ml, controls 80+/-15 ml; P < 0.05) in both groups of athletes but all other functional data were similar between groups. As in male athletes, female rowers, canoeists and cyclists displayed significantly larger left ventricular cavity dimensions and wall thicknesses than controls.