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Background Menopause represents a turning point where vascular damage begins to outweigh reparative processes, leading to increased cardiovascular disease (CVD) risk. Exercise training reduces CVD risk in postmenopausal females via improvements in traditional risk factors and direct changes to the vasculature. We assessed the effect of moderate (MODERATE-IT) versus heavy (HEAVY-IT) intensity interval exercise training upon markers of cardiovascular health and vascular repair in postmenopausal females. Methods Twenty-seven healthy postmenopausal females (56 ± 4 yr) were assigned to 12 weeks of either MODERATE-IT or HEAVY-IT, twice per week. MODERATE-IT consisted of 10s work, and 10s active recovery repeated for 30 min. HEAVY-IT comprised 30s work, and 30s active recovery repeated for 21 ± 2 min. Endothelial function (flow-mediated dilation), arterial stiffness (pulse wave velocity), and V̇O2peak were assessed pre-training and post-training. Blood samples were obtained pre-training and post-training for enumeration of circulating angiogenic cells (CACs), culture of CACs, and lipoprotein profile. Results V̇O2peak increased 2.4 ± 2.8 ml/kg/min following HEAVY-IT only (p 0.05). Peripheral pulse wave velocity reduced 8% with exercise training, irrespective of intensity (p 0.05). CAC adhesion to vascular smooth muscle cells (VSMC) increased 30 min post plating following MODERATE-IT only (p

Fatiguing expiratory muscle work in otherwise resting humans elicits an increase in sympathetic motor outflow; whether limb blood flow ([Formula: see text]) and leg vascular resistance (LVR) are affected remains unknown. We found that fatiguing expiratory resistive loaded breathing (ERL) did not affect group mean [Formula: see text] or LVR. However, within-breath oscillations in [Formula: see text] may reflect a sympathetically mediated vasoconstriction that was counteracted by transient increases in [Formula: see text] due to the mechanical effects of high intra-abdominal pressure during ERL.

Background Epidemiological studies have indicated an inverse association between citrus fruit consumption and cardiovascular disease (CVD) risk. There is, however, a paucity of data concerning effects of blood orange juice (BOJ) intake on endothelial function and cardiovascular risk biomarkers. Objectives We examined short-term effects of BOJ on endothelial function, blood pressure, lipid profile, and inflammatory markers in healthy participants of European origin who were overweight or obese. Methods In a randomized, controlled, single-blind, crossover trial, 15 men and women (age: 28.7 ± 6.5 y; BMI: 28.3 ± 3.1 kg/m2) consumed BOJ or a sugar-matched control drink (CD) (200 mL twice daily) for 2 wk with a washout period of 1 wk. Endothelial function, measured as flow-mediated dilation (FMD) (primary outcome), and the secondary outcomes blood pressure, anthropometric measures, lipid profile, inflammatory markers, markers of vasodilation and vasoconstriction, and urinary flavanone metabolites were evaluated prior to and at the end of each treatment period following an overnight fast. Changes between treatments over time were assessed using repeated-measures ANOVA. Results The results demonstrate a significant increase in FMD following BOJ consumption (pre: 8.15% ± 2.92%; post: 10.2% ± 3.31%; P = 0.002) compared with CD (pre: 8.11% ± 2.52%; post: 7.77% ± 2.43%; time × treatment interaction: P = 0.001). Concurrent significant increases in urinary hesperetin-3'-glucuronide and hesperetin-7-glucuronide were observed following BOJ supplementation only (time × treatment interaction: P ≤ 0.01). Baseline blood pressure, lipid profile, high-sensitivity C-reactive protein, and endothelin-1 were generally within healthy ranges and unaffected by the intervention. Conclusions A 2-wk consumption of BOJ exerted favorable effects on endothelial function in healthy women and men who were overweight or obese, which is likely mediated by the combined actions of anthocyanin and flavanone metabolites on mechanisms that contribute to enhancing NO bioavailability. This trial was registered at clinicaltrials.gov as NCT03611114.

The mechanism(s) of exercise intolerance at V˙O2max remain poorly understood. In health, standard ramp-incremental (RI) exercise is limited by fatigue-induced reductions in maximum voluntary cycling power. Whether neuromuscular fatigue also limits exercise when the RI rate is slow and RI peak power at intolerance is lower than standard RI exercise, is unknown.In twelve healthy participants, maximal voluntary cycling power was measured during a short (~6 s) isokinetic effort at 80 rpm (Piso) at baseline and, using an instantaneous switch from cadence-independent to isokinetic cycling, immediately at the limit of RI exercise with RI rates of 50, 25, and 10 W·min-1 (RI-50, RI-25, and RI-10). Breath-by-breath pulmonary gas exchange was measured throughout.Baseline Piso was not different among RI rates (analysis of variance; P0.05). Tolerable duration increased with decreasing RI rate (RI-50, 411 ± 58 s vs RI-25, 732 ± 93 s vs RI-10, 1531 ± 288 s; P0.05). At intolerance, V˙O2peak was not different among RI rates (analysis of variance; P0.05), but RI peak power decreased with RI rate (RI-50, 361 ± 48 W vs RI-25, 323 ± 39 W vs RI-10, 275 ± 38 W; P0.05). Piso at intolerance was 346 ± 43 W, 353 ± 45 W, and 392 ± 69 W for RI-50, RI-25, and RI-10, respectively (P0.05 for RI-10 vs RI-50 and RI-25). At intolerance, in RI-50 and RI-25, Piso was not different from RI peak power (P0.05), thus there was no "power reserve." In RI-10, Piso was greater than RI peak power at intolerance (P0.001), that is, there was a "power reserve."In RI-50 and RI-25, the absence of a power reserve suggests the neuromuscular fatigue-induced reduction in Piso coincided with V˙O2max and limited the exercise. In RI-10, the power reserve suggests neuromuscular fatigue was insufficient to limit the exercise, and additional mechanisms contributed to intolerance at V˙O2max.

ObjectivesThis study aimed to characterise the exercise performed in UK cardiac rehabilitation (CR) and explore relationships between exercise dose and changes in physiological variables.DesignObservational cohort study.SettingOutpatient community-based CR in Leeds, UK. Rehabilitation sessions were provided twice per week for 6 weeks.ParticipantsSixty patients (45 male/15 female 33–86 years) were recruited following referral to local outpatient CR.Outcome measuresThe primary outcome was heart rate achieved during exercise sessions. Secondary outcomes were measured before and after CR and included incremental shuttle walk test (ISWT) distance and speed, blood pressure, brachial artery flow-mediated dilatation, carotid arterial stiffness and accelerometer-derived habitual physical activity behaviours.ResultsThe mean % of heart rate reserve patients exercised at was low and variable at the start of CR (42%±16 %) and did not progress by the middle (48%±17 %) or end (48%±16 %) of the programme. ISWT performance increased following CR (440±150 m vs 633±217 m, p0.05).ConclusionPatients in a UK CR cohort exercise at intensities that are variable but generally low. The exercise dose achieved using this CR format appears inadequate to impact markers of health. Attending CR had no effect on physical activity behaviours. Strategies to increase the dose of exercise patients achieve during CR and influence habitual physical activity behaviours may enhance the effectiveness of UK CR.

Background The role of omega-3 polyunsaturated fatty acids (n-3PUFA), and the potential impact of n-3PUFA supplementation, in the treatment and management of type 1 diabetes (T1D) remains unclear and controversial. Therefore, this study aimed to examine the efficacy of daily high-dose-bolus n-3PUFA supplementation on vascular health, glycaemic control, and metabolic parameters in subjects with T1D. Methods Twenty-seven adults with T1D were recruited to a 6-month randomised, double-blind, placebo-controlled trial. Subjects received either 3.3 g/day of encapsulated n-3PUFA or encapsulated 3.0 g/day corn oil placebo (PLA) for 6-months, with follow-up at 9-months after 3-month washout. Erythrocyte fatty acid composition was determined via gas chromatography. Endpoints included inflammation-associated endothelial biomarkers (vascular cell adhesion molecule-1 [VCAM-1], intercellular adhesion molecule-1 [ICAM-1], E-selectin, P-selectin, pentraxin-3, vascular endothelial growth factor [VEGF]), and their mediator tumor necrosis factor alpha [TNFα] analysed via immunoassay, vascular structure (carotid intima-media thickness [CIMT]) and function (brachial artery flow mediated dilation [FMD]) determined via ultrasound technique, blood pressure, glycosylated haemoglobin (HbA1c), fasting plasma glucose (FPG), and postprandial metabolism. Results Twenty subjects completed the trial in full. In the n-3PUFA group, the mean ± SD baseline n-3PUFA index of 4.93 ± 0.94% increased to 7.67 ± 1.86% (P P P P > 0.05). Conclusions This study indicates that daily high-dose-bolus of n-3PUFA supplementation for 6-months does not improve vascular health, glucose homeostasis, or metabolic parameters in subjects with T1D. The findings from this preliminary RCT do not support the use of therapeutic n-3PUFA supplementation in the treatment and management of T1D and its associated complications. Trial Registration ISRCTN, ISRCTN40811115. Registered 27 June 2017, http://www.isrctn.com/ISRCTN40811115.

Over the last 10 years, evidence has emerged that too much sedentary time (e.g. time spent sitting down) has adverse effects on health, including an increased risk of cardiovascular disease incidence and mortality. A considerable amount of media attention has been given to the topic. The current UK activity guidelines recommend that all adults should minimize the amount of time spent being sedentary for extended periods. How best to minimize sedentary behavior is a focus of ongoing research. Understanding the impact of sedentary behaviors on the health of people with stroke is vital as they are some of the most sedentary individuals in society. Implementing strategies to encourage regular, short breaks in sedentary behaviors has potential to improve health outcomes after stroke. Intervention work already conducted with adults and older adults suggests that sedentary behaviors can be changed. A research priority is to explore the determinants of sedentary behavior in people with stroke and to develop tailored interventions.

Endothelial cell phenotype and endothelial function are regulated by hemodynamic forces, particularly wall shear stress (WSS). During a single bout of exercise, the specific exercise protocol can affect in-exercise WSS patterns and, consequently, endothelial function. MicroRNAs might provide a biomarker of in-exercise WSS pattern to indicate whether a specific exercise bout will have a positive effect on endothelial function. We evaluated the effect of acute interval (IT) and continuous (CON) in-exercise WSS patterns upon postexercise endothelial function and circulating microRNA (miR)-21 expression. Methods and results: 13 participants performed CON and 3 different IT exercise protocols matched for duration and intensity on separate days. Oxygen uptake, heart rate, and brachial artery blood flow were recorded throughout the exercise. Brachial artery flow-mediated dilation (FMD) was performed pre-exercise and 15 min postexercise. Plasma samples were acquired pre-exercise and 6 h postexercise to determine miR-21 expression. In-exercise shear rate (SR) patterns (a surrogate of WSS) differed according to the CON or IT work-rate profile. In-exercise anterograde SR was greater in CON than IT exercise ( P < 0.05), but retrograde SR was equivalent between exercise protocols ( P > 0.05). Oscillatory shear index was higher during IT versus CON exercise ( P < 0.05). Postexercise FMD increased (pre: 7.08% ± 2.95%, post: 10.54% ± 4.24%, P < 0.05), whereas miR-21 expression was unchanged (pre: 12.0% ± 20.7% cel-miR-39, post: 11.1 ± 19.3% cel-miR-39, P > 0.05) with no effect of exercise protocol ( P > 0.05). Conclusions: CON and IT exercise induced different SR patterns but equivalent improvements in acute endothelial function. The absence of change in miR-21 expression suggests that miR-21 is not a suitable biomarker of exercise-induced SR. NEW & NOTEWORTHY Interval exercise has the potential to negatively impact vascular adaptations because of repeated oscillations in vascular shear. To our knowledge, we are the first to continuously assess exercise-induced shear throughout different acute exercise protocols and examine its relationship with acute endothelial function and a circulating biomarker of shear (miR-21). These experiments provide clear data indicating enhancement of the acute vascular response from differing interval exercise protocols, with the study also providing detailed vascular and shear responses for future reference.

Background Randomized controlled trials (RCTs) suggest that supplementation with omega-3 polyunsaturated fatty acids (n-3PUFAs) may favourably modify cardiometabolic biomarkers in type 2 diabetes (T2DM). Previous meta-analyses are limited by insufficient sample sizes and omission of meta-regression techniques, and a large number of RCTs have subsequently been published since the last comprehensive meta-analysis. Updated information regarding the impact of dosage, duration or an interaction between these two factors is therefore warranted. The objective was to comprehensively assess the effect of n-3PUFAs supplementation on cardiometabolic biomarkers including lipid profiles, inflammatory parameters, blood pressure, and indices of glycaemic control, in people with T2DM, and identify whether treatment dosage, duration or an interaction thereof modify these effects. Methods Databases including PubMed and MEDLINE were searched until 13th July 2017 for RCTs investigating the effect of n-3PUFAs supplementation on lipid profiles, inflammatory parameters, blood pressure, and indices of glycaemic control. Data were pooled using random-effects meta-analysis and presented as standardised mean difference (Hedges g) with 95% confidence intervals (95% CI). Meta-regression analysis was performed to investigate the effects of duration of supplementation and total dosage of n-3PUFAs as moderator variables where appropriate. Results A total of 45 RCTs were identified, involving 2674 people with T2DM. n-3PUFAs supplementation was associated with significant reductions in LDL [ES: − 0.10, (95% CI − 0.17, − 0.03); p = 0.007], VLDL (ES: − 0.26 (− 0.51, − 0.01); p = 0.044], triglycerides (ES: − 0.39 (− 0.55, − 0.24; p ≤ 0.001] and HbA1c (ES: − 0.27 (− 0.48, − 0.06); p = 0.010]. Moreover, n-3PUFAs supplementation was associated with reduction in plasma levels of TNF-α [ES: − 0.59 (− 1.17, − 0.01); p = 0.045] and IL-6 (ES: − 1.67 (− 3.14, − 0.20); p = 0.026]. All other lipid markers, indices of glycaemic control, inflammatory parameters, and blood pressure remained unchanged (p > 0.05). Conclusions n-3PUFAs supplementation produces favourable hypolipidemic effects, a reduction in pro-inflammatory cytokine levels and improvement in glycaemia. Neither duration nor dosage appear to explain the observed heterogeneity in response to n-3PUFAs. Trial registration This trial was registered at http://www.crd.york.ac.uk as CRD42016050802

Background:Physical activity is important for maintaining independence and quality of life in older people living in care homes. Little is known about patterns of physical activity or sedentary behavior in this population.Methods:Thirty-three care home residents (82.6 ± 9.2 years) wore an ActiGraph GTX3 accelerometer for seven days, which provided minutes of sedentary behavior and low, light, and moderate-to-vigorous physical activity. Participants undertook the Mini-Mental State Examination and care staff reported activities of daily living (Barthel index) and functional ambulation classification (FAC) for each participant.Results:Participants spent on average 79% of their day sedentary, 14% in low, 6% in light, and 1% in moderate-to-vigorous physical activity. Activity levels did not significantly differ between days or hours of the day (P > .05).Conclusion:Levels of physical activity were very low and time being sedentary was high. This study can inform physical activity and sedentary behavior interventions for care homes’ residents.

Scaling left ventricular (LV) mass and other cardiac dimensions to account for individual body size is important. The traditional method of simple ratio scaling using, for example, body surface area (BSA) assumes a linear and proportional relationship and accurate measurement of both LV mass and BSA. These assumptions can be questioned; hence, we examined the appropriateness of methods and different indices using highly accurate magnetic resonance imaging scans. Cardiac and whole-body scans were performed in 172 young, healthy, male subjects (age range, 17-28 years) to assess LV mass, volume, linear dimensions, lean body mass and fat mass. Height, body mass and BSA were determined anthropometrically. Relationships were examined for linearity and closeness of fit using log-log least-squares linear regression to determine the slope exponent b (where 1.0 indicates linearity). The relationship between LV mass and lean body mass (b=.90+/-.15; r(2)=.66) was linear and geometrically consistent. This was also the case for LV end-diastolic volume (b=.70), although the confidence intervals were broader (+/-0.32) and the r(2) (.31) smaller. The relationships between LV mass, volume and other variables were generally not linear or geometrically consistent. LV linear dimensions did not demonstrate any linear relationships, and in particular, those with BSA were extremely poor (r(2)=.02-.09). In summary, the traditional scaling of LV measurements to BSA does not remove the influence of body size and other techniques should be considered. Lean body mass was the most appropriate variable for simple indexing of LV mass. No body size variable had a linear and proportional relationship with LV linear dimensions, and the use of simple ratio scaling for these is seriously questioned.

The World Health Organization and a number of national bodies recommend adults undertake at least 150 min/week of moderate intensity physical activity, or 75 min/week of vigorous intensity physical activity. However, a large proportion of the population do not achieve these targets. Lack of time is often cited as a primary barrier,1 and many researchers have suggested that high-intensity interval training (HIIT), with interval durations from 10 s to 4 min and intensities ranging from 85% maximal heart rate (HRmax) to ‘all out’ efforts, may provide a time-efficient solution to improve public health.2 A wealth of evidence has demonstrated that HIIT can elicit a range of health benefits such as improved cardiorespiratory fitness, insulin sensitivity and vascular function, with these benefits being of at least a similar magnitude to those seen with standard moderate intensity physical activity interventions.3 ,4 These data are clear and convincing. However, they largely emanate from …

Traditional continuous aerobic exercise training attenuates age-related increases of arterial stiffness, however, training studies have not determined whether metabolic stress impacts these favourable effects. Twenty untrained healthy participants (n = 11 heavy metabolic stress interval training, n = 9 moderate metabolic stress interval training) completed 6 weeks of moderate or heavy intensity interval training matched for total work and exercise duration. Carotid artery stiffness, blood pressure contour analysis, and linear and non-linear heart rate variability were assessed before and following training. Overall, carotid arterial stiffness was reduced (p 0.05). This study demonstrates the effectiveness of interval training at improving arterial stiffness and autonomic function, however, the metabolic stress was not a mediator of this effect. In addition, these changes were also independent of improvements in aerobic capacity, which were only induced by training that involved a high metabolic stress.

Introduction It is well established that endurance exercise results in cardiac adaptation including eccentric hypertrophy of the left ventricle which can complicate the differential diagnosis of the athletic heart from some cardiac pathologies that may pre-dispose to sudden cardiac death. The impact of physiological conditioning on RV structure and function, and a similar diagnostic challenge with arrhythmogenic right ventricular cardiomyopathy (ARVC), has received less attention. A recent guideline paper from the American Society of Echocardiography (ASE) has provided a range for normal RV dimensions and functional deformation. These guidelines suggest the RV inflow (RVI) should be 36 mm or 21 mm/m 2 is a major criterion for the diagnosis of ARVC and furthermore longitudinal RV deformation has been shown to be impaired in these patients. In view of this, the aims of this study are twofold: To provide a range of absolute values for RV dimensions in 102 endurance athletes as well as providing a range of data indexed for body surface area (BSA). To provide normal athlete data for indices of RV strain (ɛ) and strain rate (SR). Methods and Results One hundred and two (102) endurance athletes (86 males and 16 females) with a broad age range (mean ± SD age (range)=36 ± 11 (21–71) years) volunteered and were consecutively enrolled in the study. All subjects were either endurance runners or cyclists and were scanned at peak condition. Echocardiography provided measurements of RVI, RV length, RVOT and RV diastolic area (RVDarea). A 2D strain technique was utilised to provide indices of RVɛ and systolic and diastolic SR. The values for RVI ranged from 30 to 55 mm with 57% of the population having values greater than the normal range. Proximal RVOT ranged from 26 to 49 mm with 40% of the population above the normal range. 28% of the population had RVOT values greater than the proposed “major criteria” for ARVC. RV length ranged from 70 to 110 mm and RVDarea from 13 to 38 cm 2 with values falling above ASE cut-offs in 69% and 59% of the population, respectively. When indexed (ratio scaling) for BSA proximal RVOT ranged from 13 to 25 mm/m 2 with 6% of the population meeting the major criteria for ARVC. Peak RVɛ ranged from −18 to −41% and peak RV SRS′ from −0.75 to −2.65 l/s, consistent with normal ranges proposed by the ASE. RV diastolic deformation indices displayed marked individual variability with a dominant SRE′ (mean ± SD=2.0±0.61 l/s) and smaller SRA′ (1.25±0.56 l/s). Conclusion RV dimensions in endurance athletes are higher than those proposed as “normal” and likewise may be consistent with the criteria for ARVC. Despite this enlargement, RV function in endurance athletes is preserved and therefore the role of RV strain imaging may provide additional diagnostic value in differentiating physiological from pathological adaptation.

The mechanism for slow pulmonary O2uptake (V̇o2) kinetics in patients with chronic heart failure (CHF) is unclear but may be due to limitations in the intramuscular control of O2utilization or O2delivery. Recent evidence of a transient overshoot in microvascular deoxygenation supports the latter. Prior (or warm-up) exercise can increase O2delivery in healthy individuals. We therefore aimed to determine whether prior exercise could increase muscle oxygenation and speed V̇o2kinetics during exercise in CHF. Fifteen men with CHF (New York Heart Association I–III) due to left ventricular systolic dysfunction performed two 6-min moderate-intensity exercise transitions ( bouts 1 and 2, separated by 6 min of rest) from rest to 90% of lactate threshold on a cycle ergometer. V̇o2was measured using a turbine and a mass spectrometer, and muscle tissue oxygenation index (TOI) was determined by near-infrared spectroscopy. Prior exercise increased resting TOI by 5.3 ± 2.4% ( P = 0.001), attenuated the deoxygenation overshoot (−3.9 ± 3.6 vs. −2.0 ± 1.4%, P = 0.011), and speeded the V̇o2time constant (τV̇o2; 49 ± 19 vs. 41 ± 16 s, P = 0.003). Resting TOI was correlated to τV̇o2before ( R2= 0.51, P = 0.014) and after ( R2= 0.36, P = 0.051) warm-up exercise. However, the mean response time of TOI was speeded between bouts in half of the patients (26 ± 8 vs. 20 ± 8 s) and slowed in the remainder (32 ± 11 vs. 44 ± 16 s), the latter group having worse New York Heart Association scores ( P = 0.042) and slower V̇o2kinetics ( P = 0.001). These data indicate that prior moderate-intensity exercise improves muscle oxygenation and speeds V̇o2kinetics in CHF. The most severely limited patients, however, appear to have an intramuscular pathology that limits V̇o2kinetics during moderate exercise.

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 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.

This study investigated the contribution of muscle architecture to the differences in the torque-velocity and power-velocity relationships between older (OM n = 9, aged 69-82 years) and younger men (YM n = 15, aged 19-35 years). Plantarflexors' (PF) maximal isometric and concentric torques were recorded at 0.87, 1.75, 2.62, 3.49 and 4.36 rad s(-1). Physiological cross-sectional area (PCSA) was calculated as the ratio of muscle volume (determined by magnetic resonance imaging) to muscle fascicle length (Lf, measured by ultrasonography). GM PCSA and Lf of the OM were, respectively, 14.3% (P < 0.05) and 19.3% (P < 0.05) smaller than of the YM. In the OM, GM maximum isometric torque and maximum contraction velocity (Vmax), estimated from Hill's equation were, respectively, 48.5 and 38.2% lower (P < 0.001) than in the YM. At all contraction velocities, the OM produced less torque than the YM (46.3% of YM at 0.87 rad s(-1) to 14.7% at 4.36 rad s(-1), P < 0.001). Peak power (PP) of the OM was 80% lower than that of the YM and normalisation of PP to muscle volume only reduced this difference by 10%. Normalisation of torque to PCSA reduced, but did not eliminate, differences in torque between YM and OM (9.6%) and differences in torque/PCSA increased with contraction velocity (P < 0.05). After normalisation of velocity to Lf, the difference in Vmax between the OM and the YM was reduced to 15.9%. Thus, although muscle architecture contributes significantly to the differences in the torque- and power-velocity properties of OM and YM, other contractile factors, intrinsic to the muscle, seem to play a role. It is noteworthy that the deficit in PP between OM and YM is far greater than that of muscle torque, even after normalisation of PP to muscle volume. This finding likely plays an important role in the loss of mobility in old age.

Sarcopenia and muscle weakness are well-known consequences of aging. The aim of the present study was to ascertain whether a decrease in fascicle force (Ff) could be accounted for entirely by muscle atrophy. In vivo physiological cross-sectional area (PCSA) and specific force (Ff/PCSA) of the lateral head of the gastrocnemius (GL) muscle were assessed in a group of elderly men [EM, aged 73.8 yr (SD 3.5), height 173.4 cm (SD 4.4), weight 78.4 kg (SD 8.3); means (SD)] and for comparison in a group of young men [YM, aged 25.3 yr (SD 4.4), height 176.4 cm (SD 7.7), weight 79.1 kg (SD 11.9)]. GL muscle volume (Vol) and Achilles tendon moment arm length were evaluated using magnetic resonance imaging. Pennation angle and fiber fascicle length (Lf) were measured using B-mode ultrasonography during isometric maximum voluntary contraction of the plantar flexors. PCSA was estimated as Vol/Lf. GL Ff was calculated by dividing Achilles tendon force by the cosine of θ, during the interpolation of a supramaximal doublet, and accounting for antagonist activation level (assessed using EMG), Achilles tendon moment arm length, and the relative PCSA of the GL within the plantar flexor group. Voluntary activation of the plantar flexors was lower in the EM than in the YM (86 vs. 98%, respectively, P < 0.05). Compared with the YM, plantar flexor maximal voluntary contraction torque and Ff of the EM were lower by 47 and 40%, respectively ( P < 0.01). Both Vol and PCSA were smaller in the EM by 28% ( P < 0.01) and 16% ( P < 0.05), respectively. Also, pennation angle was 12% smaller in the EM, whereas there was no significant difference in Lf between the YM and EM. After accounting for differences in agonists and antagonists activation, the Ff/PCSA of the EM was 30% lower than that of the YM ( P < 0.01). These findings demonstrate that the loss of muscle strength with aging may be explained not only by a reduction in voluntary drive to the muscle, but mostly by a decrease in intrinsic muscle force. This phenomenon may possibly be due to a reduction in single-fiber specific tension.

The aim of the present study was to examine the pattern of cardiovascular recovery from exercise in 15 women (age, 20.3 +/- 1.4 years; body mass, 61.5 +/- 4.3 kg) across two phases of oral contraceptive (OC) use: 21 days of consumption and 7 days of withdrawal. Cardiovascular recovery was measured in the supine position for 60 min following 30 min of exercise at 60% maximal rate of oxygen consumption (VO2,max). Central and peripheral haemodynamics were assessed during consumption and withdrawal of the OC pill using occlusion plethysmography, Doppler flowmetry and echocardiography. Significant hypotension occurred following exercise (P0.05), returning to baseline values after 60 min. The peak hypotension occurred 5 min into recovery. Cardiac output and heart rate were elevated for 60 min following exercise (P0.05), whilst stroke volume remained at baseline values. Heart rate was greater throughout recovery during consumption compared to withdrawal (P0.05); however, although there was a trend for greater responses during consumption, phase of OC use did not affect the other central cardiovascular variables (P0.05). Post-exercise blood flow parameters were not significantly affected by exercise or OC phase; however, calf blood flow was greater, and resistance to flow lower during consumption (P0.05). The pattern of post-exercise fluctuations in cardiovascular parameters may differ from those seen in men, whilst oestrogen variation may influence research findings.

Introduction: The improvement of vascular health in the exercising limb can be attained by sprint interval training (SIT). However, the effects on systemic vascular function and on circulating angiogenic cells (CACs) which may contribute to endothelial repair have not been investigated. Additionally, a comparison between SIT and sprint continuous training (SCT) which is less time committing has not been made. Methods: 12 women (22±2 yrs) completed 12 sessions of either SIT (n = 6) or work-matched SCT (n = 6) on 3 days/week. Pre and post-training assessments included brachial artery endothelial function and peripheral blood analysis for CAC number (CD34+/CD34+CD45dim). CAC function was measured by migration and adhesion assays. Cardio-respiratory fitness, carotid arterial stiffness and carotid-radial and brachial-foot pulse wave velocity (PWV) were also evaluated. Results: CD34+ CACs increased following training in both groups but CD34+CD45dim did not (Pre CD34+: 40±21/105 leukocytes, Post CD34+: 56±24/105 leukocytes, main time effect p0.05). Discussion: SCT involving little time commitment is comparable to SIT in increasing CD34+ cell number and [Formula: see text]. An increased mobilisation of CD34+ CACs suggests that sprint training may be an effective method to enhance vascular repair.

Cyclic variations in physiological and endocrinolgical baselines are known to be consistent with the eumenorrheic (healthy) menstrual cycle. The aim of this study was to examine the interaction of these variations with the physiological responses to repeated lifting. Sixteen females visited the laboratory in each of five phases of their menstrual cycle. During each visit, subjects performed a repetitive lifting task, lifting a weighted box, from knee to shoulder height, at six repetitions per minute for 10 min. Oxygen consumption, minute ventilation, heart rate (HR), and perceived exertion were monitored throughout the task. The variation in physiological and subjective responses to lifting with menstrual cycle phase did not reach statistical significance (p > .05). However, the HR response to lifting was elevated by approximately 10 beats min−1 in the postovulatory phases of the cycle (effect size > 0.61). Although the impact of the menstrual cycle upon lifting performance is minimal, alterations in HR must be taken into account in determining new international standards for manual handling. Key words: lifting, maximal oxygen consumption, subjective response, effect size

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

© 2013 Rakobowchuk et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Non-invasive forearm ischemia-reperfusion injury and low flow induced vascular dysfunction models provide methods to evaluate vascular function. The role of oestrogen, an endogenous anti-oxidant on recovery from ischemia-reperfusion injury has not been evaluated nor has the impact of prolonged low flow on vascular function been established. Eight healthy women (33610 yr) attended the lab during the follicular, ovulatory and mid-luteal phases of their menstrual cycles. After 30 minutes of rest, brachial artery vascular function was assessed by ultrasound measurements of diameter changes during 5 minutes of forearm ischemia and 3 minutes after. Subsequently, a 20-minute forearm ischemia period was completed. Further, vascular function assessments were completed 15, 30 and 45 minutes into recovery. Flow-mediated dilation, lowflow-mediated constriction, and reactive hyperaemia proximal to the area of ischemia were determined. Flow-mediated dilation was reduced at 15 minutes of recovery but recovered at 30 and 45 minutes (PRE: 7.161.0%, POST15:4.560.6%, POST30:5. 560.7% POST45:5.960.4%, p,0.01). Conversely, low-flow mediated constriction increased (PRE: 21.360.4%, POST15: 23.360.6%, POST30: 22.560.5% POST45: 21.560.12%, p,0.01). Reactive hyperaemia was reduced throughout recovery (p,0.05). Data were unaffected by menstrual phase. Prolonged low flow altered vascular function and may relate as much to increased vasoconstriction as with decreased vasodilation. Reductions in anterograde shear and greater retrograde shear likely modulate the brachial artery response, but the reduced total shear also plays an important role. The data suggest substantial alterations in vascular function proximal to areas of ischemia with potential clinical implications following reperfusion. British Heart Foundation (PG/08/060/25340),a Physiological Society summer studentship to SG, and a Wellcome Trust Vacation Studentship to EP.

The tolerable duration of continuous high-intensity exercise is determined by the hyperbolic Speed-tolerable duration (S-tLIM) relationship. However, application of the S-tLIM relationship to normalize the intensity of High-Intensity Interval Training (HIIT) has yet to be considered, with this the aim of present study. Subjects completed a ramp-incremental test, and series of 4 constant-speed tests to determine the S-tLIM relationship. A sub-group of subjects (n = 8) then repeated 4 min bouts of exercise at the speeds predicted to induce intolerance at 4 min (WR4), 6 min (WR6) and 8 min (WR8), interspersed with bouts of 4 min recovery, to the point of exercise intolerance (fixed WR HIIT) on different days, with the aim of establishing the work rate that could be sustained for 960 s (i.e. 4×4 min). A sub-group of subjects (n = 6) also completed 4 bouts of exercise interspersed with 4 min recovery, with each bout continued to the point of exercise intolerance (maximal HIIT) to determine the appropriate protocol for maximizing the amount of high-intensity work that can be completed during 4×4 min HIIT. For fixed WR HIIT tLIM of HIIT sessions was 399±81 s for WR4, 892±181 s for WR6 and 1517±346 s for WR8, with total exercise durations all significantly different from each other (P0.050). However, there was significantly less high-intensity work completed during bouts 2 (153.5±40. 9 m), 3 (136.9±38.9 m), and 4 (136.7±39.3 m), compared with bout 1 (264.9±58.7 m; P>0.050). These data establish that WR6 provides the appropriate work rate to normalize the intensity of HIIT between subjects. Maximal HIIT provides a protocol which allows the relative contribution of the work rate profile to physiological adaptations to be considered during alternative intensity-matched HIIT protocols.

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.

Physiological variables must often be scaled for body size differences to permit meaningful comparisons between groups. Using multivariate allometric scaling (MAS), this study aimed to compare the anaerobic performance of adult males and females in 12 pairs matched for physical activity status. Peak power output (PPO) was assessed via a 30-s supramaximal cycle ergometer test. Fat-free mass (FFM) and thigh muscle and bone cross-sectional area (CSA) were determined anthropometrically and served as indicators of active musculature. The MAS revealed power functions of the form PPO = a∙genderc∙FFMb (or CSAb). Common b exponents of 0.1 were identified for both FFM and CSA (negative allometry). Sex differences were found in absolute PPO (1,252 vs. 681 W, p 0.1 and CSA0.1 entered as cavariates) did not eliminate the sex difference (adjusted means 1,243 vs. 690 W, p

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).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 ICC0.6 and CoV15%. 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.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).

Exercise-induced left ventricular hypertrophy is well documented, but whether this occurs merely in line with concomitant increases in lean body mass is unclear. PURPOSE: Our aim was to model the extent of left ventricular hypertrophy associated with increased lean body mass attributable to an exercise training program. METHODS: Cardiac and whole-body magnetic resonance imaging was performed before and after a 10-wk intensive British Army basic training program in a sample of 116 healthy Caucasian males (aged 17-28 yr). The within-subjects repeated-measures allometric relationship between lean body mass and left ventricular mass was modeled to allow the proper normalization of changes in left ventricular mass for attendant changes in lean body mass. To linearize the general allometric model (Y = aX b), data were log-transformed before analysis; the resulting effects were therefore expressed as percent changes. We quantified the probability that the true population increase in normalized left ventricular mass was greater than a predefined minimum important difference of 0.2 SD, assigning a probabilistic descriptive anchor for magnitude-based inference. RESULTS: The absolute increase in left ventricular mass was 4.8% (90% confidence interval = 3.5%-6%), whereas lean body mass increased by 2.6% (2.1%-3.0%). The change in left ventricular mass adjusted for the change in lean body mass was 3.5% (1.9%-5.1%), equivalent to an increase of 0.25 SD (0.14-0.37). The probability that this effect size was greater than or equal to our predefined minimum important change of 0.2 SD was 0.78-likely to be important. CONCLUSIONS: After correction for allometric growth rates, left ventricular hypertrophy and lean body mass changes do not occur at the same magnitude in response to chronic exercise. Copyright © 2011 by the American College of Sports Medicine.

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 (ε) was significantly reduced postrace (−27% to −24%, P =0.004), but there was no change in the rates of ε. Peak ε 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.

Two-dimensional (2D) strain imaging from speckle tracking is a Doppler independent technique allowing assessment of left ventricular (LV) strain (ɛ); systolic strain rate (SRs') and early diastolic strain rate (SRe') in the radial and circumferential planes. We set out to investigate whether (i) these parameters facilitated assessment of dyssynchronous contraction and (ii) these measures could predict response to cardiac resynchronization therapy (CRT).Forty-one patients with severe, symptomatic heart failure on optimal medical therapy were recruited. Thirty-two healthy subjects were used as controls. Time to peak ɛ, SRs', and SRe' of 6 LV segments were measured in the parasternal short axis prior to and 6 weeks post CRT implantation. Time delays between segments were then calculated and ANOVA assessed for prediction of response, classified as reduction in LV end systolic volume of15%. 2D strain demonstrated significantly more dyssynchronous contraction in the heart failure population at baseline compared to healthy controls. Significant reduction in dyssynchrony was seen in ɛ and SRs' following CRT, largely confined to those with evidence of remodeling. The time delay between peak circumferential SRs' of opposing walls was the best predictor of reverse remodeling.2D strain imaging appears to be a useful measure to predict response to CRT. The time to peak circumferential SR is a new predictor of response.

Background Standard marathon running can result in a depression of left ventricular (LV) diastolic function during early recovery. Left atrial (LA) mechanics are integral in maintaining an early diastolic pressure gradient as well as being responsive to changes in LV diastolic function, and therefore the detailed assessment of LA mechanics may provide further insight. The aim of this study was to determine the impact of prolonged strenuous exercise on mechanics of the left atrium and the association with changes in LV diastolic function. Methods Myocardial speckle-tracking echocardiograms of the left atrium and left ventricle were obtained prior to, immediately after, and 6 hours after the completion of a marathon (42.2 km) in 17 healthy adult men. Speckle tracking was used to determine peak atrial deformation, early diastolic deformation rate, and contractile function, including atrial activation time. LA volumes throughout the cardiac cycle were also assessed to provide reservoir, conduit, and booster pump volumes. Diastolic assessment of the left ventricle included peak early diastolic strain rate, late diastolic strain rate, and standard indices. Temporal assessment of LV “twist” and “untwist” was also evaluated. Results All 17 subjects completed the marathon (mean finishing time, 209 ± 19 minutes; range, 173-241 minutes). Although contractile function was significantly increased, there was a reduction in early diastolic deformation rate that was correlated with reduced atrial deformation. Atrial activation time was significantly increased after the race. All LV indices of diastolic function were reduced in early diastole, whereas late diastolic function was increased after the race. LV torsion was significantly reduced at end-systole and significantly elevated in the isovolumic period and early diastole, after the race. All indices returned toward baseline at 6 hours after exercise. Conclusions This study demonstrates transient changes in LV diastolic relaxation following prolonged exercise that appear to have a direct impact on subsequent LA deformation. The impact of reduced LA preload on these findings and the delay in LA activation time requires further exploration.

The aim of the present investigation was to determine whether muscle force per physiological cross sectional area (PCSA) of the lateral gastrocnemius (GL) of elderly males increased following a 12-month physical training programme. Eleven elderly males were assigned to a 12-month training programme (TRN mean age 72.7 +/- 3.3 years, mean +/- SD) and eight elderly males were allocated to a control group (CTRL, 73.9 +/- 4.0 years) who maintained their habitual physical activity levels. In vivo measurements of muscle architecture, muscle volume (VOL), achilles tendon moment arm length and plantarflexor torque were used to estimate GL PCSA (VOL/fascicle length) and specific force (GL fascicle force/GL PCSA). Maximal GL fascicle force was calculated accounting for agonist muscle activation and antagonist co-activation. Following training GL fascicle force increased by 31% (P0.01), which was not entirely accounted for by a 17% increase in PCSA (from 27.2 +/- 5.9 to 31.8 +/- 6.2 cm(2), P0.05). Specific force increased significantly from 8.9 +/- 1.9 to 11.2 +/- 3.0 N cm(-2) (P0.05). Pennation angle, but not fascicle length, increased by 12% with training (P0.05). The CTRL group showed no change in muscle size, strength or architecture over the 12-month period. In conclusion, with the level of agonist and antagonist muscle activity accounted for a 12-month strength training programme resulted in an increase in both PCSA and specific force in elderly males.

Postexercise hypotension (PEH) has been observed in males and females; however, the impact of menstrual cycle phase upon PEH has not been evaluated. We examined the pattern of PEH in the early follicular (EF), late follicular (LF), and midluteal (ML) phases of the menstrual cycle in eight eumenorrheic women following 30 min of exercise at 80% lactate threshold.Supine hemodynamic measurements were assessed at rest and then for 45 min following exercise. Blood pressure was measured with manual sphygmomanometry, calf vascular resistance (CVR) via venous occlusion plethysmography, and central hemodynamics with echocardiography.Cardiovascular parameters did not differ between menstrual phases at rest (P0.05). The pattern of PEH was unaffected by menstrual phase, but mean arterial and diastolic (DBP) pressures dropped to significantly lower levels across the recovery period in the EF phase than in the LF and ML phases (mean DBP EF: 69 +/- 4; LF 74 +/- 3; ML 72 +/- 5; P0.05). Postexercise cardiac output, stroke volume, ejection fraction, left ventricular dimensions, and heart rate did not differ across menstrual phases (P0.05). These parameters, except for left ventricular dimensions in systole and heart rate, varied with recovery time, increasing to a peak between 5 and 10 min postexercise (P0.05). CVR displayed a significant interaction between cycle phase and recovery time as resistance increased to greater values in the ML phase compared with the EF and LF phases following 30 min of postexercise recovery (P0.05).Buffering of PEH appears to be enhanced in the LF and ML phases of the cycle where estrogen concentrations are known to be elevated.

This study investigated whether loss of power with aging is fully accounted for by a decrease in muscle volume. Triceps surae power and volume (VOL) were measured in 18 older (OM: 69-82 years) and 12 younger men (YM: 19-35 years). Isokinetic peak torque was measured to determine torque-velocity and power-velocity relationships. Both peak power observed (PP(obs)) and peak power estimated from Hill's equation (PP(est)) were markedly reduced in the OM (PP(obs) was 45% and PP(est) was 43% of those of the YM). VOL was 81% of that of the YM (p

This study investigated the influence of tendon elongation (TE) on postcontraction doublet (PCD) torque in the assessment of activation in the plantar flexors of nine elderly men (EM, age 73.7 ± 3.6 yr) and nine young men (YM, age 24.7 ± 4.7 yr). Plantar flexion maximal voluntary contractions (MVC) and activation were assessed at ankle joint angles of −20° (dorsiflexion), 0°, and 20° (plantar flexion). Across the ankle joint angles tested, compared with YM, the EM had a 36–49% lower plantar flexion MVC ( P < 0.01), TE was greater by 25–31% ( P < 0.01), and electromechanical delay was 65–108% greater ( P < 0.01). Activation (PCD torque to interpolated doublet torque) was 15% lower in EM compared with YM at −20° ( P < 0.05), but no different at 0 and 20°. In the EM, PCD torque relative to MVC torque was significantly lower at 20° compared with 0° ( P < 0.05). Electromechanical delay was positively correlated with TE ( R2 = 0.489, P < 0.01). In conclusion, this investigation demonstrates that, although a negative association exists between TE and PCD torque, the consequence of a greater TE on the estimation of activation in EM is negligible. This is due to a greater influence of ankle joint angle on the occlusion of a superimposed doublet, which counteracts the lesser influence of joint angle on TE and PCD torque. However, a greater TE in EM was found to significantly increase electromechanical delay, which is expected to influence the time needed for postural readjustments.

In elderly males muscle plantar flexor maximal voluntary contraction (MVC) torque normalised to muscle volume (MVC/VOL) is reduced compared to young males as a result of incomplete muscle activation in the elderly. The aim of the present study was to determine the influence of a 12-month resistance training programme on muscle volume, strength, MVC/VOL, agonist activation and antagonist coactivation of the plantarfexors in elderly males. Thirteen elderly males aged 70 years and over (range 70-82 years), completed a 12-month whole body resistance-training programme (TRN), training three times a week. Another eight males (range 18-30 years), who maintained their habitual physical activity for the same 12-month period as the TRN group acted as controls (CTRL). Isometric plantarflexor maximal voluntary contraction (MVC) torque increased in the TRN group by 20% (P < 0.01), from 113.1 +/- 22.0 Nm to 141.5 +/- 19.2 Nm. Triceps surae volume (TS VOL) assessed using MRI, increased by 12%, from 796.3 +/- 78.9 cm(3) to 916.8 +/- 144.4 cm(3) . PF activation, measured using supramaximal double twitch interpolation, increased from 83.6+/-11.0% pre training, to 92.1 +/- 7.6% post training (P < 0.05). Dorsiflexion MVC and antagonist coactivation (assessed using surface electromyography) did not change with training. Plantarflexor MVC torque normalized for triceps surae muscle volume (MVC/VOL) was 142.6 +/- 32.4 kN m(-2) before training and 157.0 +/- 27.9 kN m(-2) after training (a non-significant increase of 8%). No significant change in any measurement was observed in the CTRL group. This study has shown that the gain in muscle strength in response to long-term (12-month) training in older men is mostly accounted for by an increased muscle volume and activation.

Previous studies have reported a decrease in muscle torque per cross-sectional area in old age. This investigation aimed at determining the influence of agonists muscle activation and antagonists co-activation on the specific torque of the plantarflexors (PF) in recreationally active elderly males (EM) and, for comparison, in young men (YM). Twenty-one EM, aged 70-82 years, and 14 YM, aged 19-35 years, performed isometric maximum voluntary contractions (MVC). Activation was assessed by comparing the amplitude of interpolated supramaximal twitch doublets at MVC, with post-tetanic doublet peak torque. Co-activation of the tibialis anterior (TA) was evaluated as the ratio of TA-integrated EMG (IEMG) activity during PF MVC compared to TA IEMG during maximal voluntary dorsiflexion. Triceps surae muscle volume (VOL) was assessed using magnetic resonance imaging (MRI), and PF peak torque was normalised to VOL (PT/VOL) since the later approximates physiological cross-sectional area (CSA) more closely than anatomical CSA. Also, physical activity level, assessed by accelerometry, was significantly lower (21%) in the elderly males. In comparison to the YM group, a greater difference in PT (39%) than VOL (19%) was found in the EM group. PT/VOL and activation capacity were respectively lower by 25% and 21% in EM compared to YM, whereas co-activation was not significantly different. In EM PT/VOL correlated with activation (R(2)=0.31, P

Rodacki CL, Fowler NE, Rodacki AL, Birch K. Stature loss and recovery in pregnant women with and without low back pain. Arch Phys Med Rehabil 2003;84:507-12. Objectives: To assess the loss of stature and its recovery in normal and pregnant women with and without low back pain (LBP) and to examine the relations between spinal shrinkage, recovery, and LBP. Design: Stature changes were measured before and after physical activity in each group and differences in response compared between groups. Setting: A laboratory environment. Participants: Thirty-one women (7 pregnant without LBP, 8 pregnant with LBP, 16 nonpregnant with no history of low back disorders) were recruited using convenience sampling. Controls were recruited from the general community; subjects in the pregnant groups were recruited from local primary care groups. Interventions: Not applicable. Main Outcome Measures: Stature change was assessed as the main outcome measure. Changes in stature were interpreted with respect to the woman[apos]s stature at the start of the trial. Results: Stature loss induced by a moderate physical activity was similar (P[gt].05) in all groups (control, [minus]3.99[plusmn]1.13mm; pregnant no back pain, [minus]4.23[plusmn]1.23mm; pregnant with back pain, [minus]4.57[plusmn]1.53mm). Differences were found after 20 minutes in a recovery position (P[lt].05): the controls were able to recover stature to a greater extent (111.2%[plusmn]13.6%) than the other groups (P[lt].05). A negative correlation was found between regain in stature and LBP in pregnant subjects (r[equals][minus].81, P[lt].05). Conclusions: The pregnant women with LBP were unable to recover stature to the same extent as the controls and pregnant women without LBP. Results suggest that LBP in pregnancy may be related to the woman[apos]s diminished ability to recover, rather than the magnitude of the spinal shrinkage imposed during the task.

Buckley JG, Jones SF, Birch KM. Oxygen consumption during ambulation: comparison of using a prosthesis fitted with and without a tele-torsion device. Arch Phys Med Rehabil 2002;83:576-81. Objective: To determine the energy expenditure and sub- jective comfort rating of walking in transtibial amputee patients using their prosthesis fitted either with or without a tele-torsion device (TT Pylon). Design: Randomized, before-after trial. Setting: Gait laboratory. Participants: Six men, moderately active, with unilateral transtibial amputation (mean age, 39.5 9.9y). Intervention: Subjects walked on a motorized treadmill using their prosthesis fitted either with (ProsWith) or without (ProsWith- out) a TT Pylon. Trials were repeated with subjects walking at speeds 100%, 130%, and 160% of their "normal" pace. Main Outcome Measures: The energy expended (VO2) and subjective comfort rating during each walking trial. Results: VO2 during walking with the prosthesis fitted with the TT Pylon was 5.4% and 9.1% lower than when using the prosthesis without the TT Pylon, at the speeds 130% and 160% of normal, respectively. Findings at the speed 160% greater than normal were significant (P.05). Two of the subjects perceived no difference in prosthetic comfort between Pros- With and ProsWithout. The other 4 subjects preferred the TT Pylon at all speeds. Conclusion: Use of a TT Pylon can significantly reduce the

Physiological and subjective responses to physical performance have been shown to interrelate with fluctuations in the female hormonal environment throughout the menstrual cycle. The aim of this study was to examine whether these fluctuations affect the strenuous performance required in manual handling. Seventeen eumenorrheic females performed lifting tasks in five phases of their menstrual cycle. These tasks were maximal isometric lifting strength (MILS) and an endurance lift at 45% MILS (t), at both knee and waist height; and the selection of a maximal acceptable load (MAL) to lift six times per min, for 10 min, in both the sagittal and asymmetric planes. Heart rate response (HR) and rating of perceived exertion (RPE) were recorded throughout each of the lifting tasks. MILS, t and the chosen MAL were unaffected by menstrual phase over both heights and planes of lift (p0.05). HR to the isometric endurance lift was greater following ovulation than prior to ovulation by approximately 7 beats.min-1 (p0.05). This was true when the data were analysed at 50, 80 and 100% of the time to volitional fatigue, and by an area under the curve procedure. HR to the dynamic lifting tasks was also elevated by approximately 7 beats.min-1 following ovulation. This difference was non-significant due to the low power of the analysis. Re-analysis of the data by re-sampling 1000 matched comparisons produced significant phase variations (p0.05). The RPE for all of the lifting tasks was independent of menstrual phase (p0.05). The impact of the eumenorrheic menstrual cycle on lifting capability was negligible in the present study. However, the results of this study indicate that all further investigations utilizing HR data to produce recommendations for health and safety in manual handling tasks must control for menstrual cycle phase in female populations.

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; P0.05). 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 (P0.05). 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; P0.05) 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.

The purpose of this study was to construct an isometric lift dynamometer and relate isometric lifting strength to dynamic measures of muscular fitness, leg and back strength and muscular power output. Thirty-one male subjects, aged 19-24 years, performed a standing broad jump (for distance), a vertical jump (for flight time), 3 maximal pulls (for peak power) on a rowing ergometer and maximal isometric leg and back extensions on a conventional dynamometer. The results of these tests were correlated with the maximum isometric lifting strength (MILS) obtained on the lift dynamometer using cluster correlation and multiple regression. Significant correlations (p0.001) were found between isometric lifting strength and back strength (BS) (r = 0.59), and leg strength (LS) (r = 0.74). A significant correlation was also noted between isometric lifting strength and both standing broad jump (SBJ) (r = 0.58, p0.001) and power output (PO) (r = 0.38, (p0.05). Multiple regression analysis was used to predict lifting performance from a battery of standard fitness tests. The prediction equation for maximal isometric lifting strength included the terms LS, BS, SBJ and PO (r = 0.80). The relation between isometric lifting strength and other muscular fitness variables suggest that the method used provides an acceptable measure of strength and an indication of the involvement of back and leg musculature in squat lifting.

GEORGE, K. P., K. M. BIRCH, B. JONES, and R. LEA. Estrogen variation and resting left ventricular structure and function in young healthy females. Med. Sci. Sports Exerc., Vol. 32, No. 2, pp. 297–303, 2000. A potential confounding factor in the interpretation of left ventricular (LV) structural and functional data in female subjects could be menstrual phase or contraceptive use upon assessment. To date no study has addressed this issue. Seventeen eumenorrheic (EU; mean ± SD age = 21 ± 3 yr) and 14 combined-oral contraceptive pill-using (COC; mean ± SD age = 21 ± 3 yr) females volunteered to participate. The EU had stable menstrual cycles and the COC had all been using the same pill preparation for a minimum of 6 months. Echocardiographic examinations occurred during the mid-follicular phase and mid-luteal phases in the EU and during mid-consumption and mid-end of withdrawal in the COC. LV structure and function were assessed using M-mode and pulsed-wave Doppler echocardiography. Data were compared via Student t-tests and limits of agreement (LoA) were calculated. Structure and function did not significantly differ between phases of the menstrual cycle or between consumption and withdrawal of oral contraception (P > 0.05). However, there was considerable variance in the LoA between variables. Smaller LoA were reported for those variables directly measured from echocardiograms compared with those from derived data. For example, in a measured variable such as LV internal dimension in diastole, the LoA data represented a variation of ± 0.4 mm (±1%) between phases. Conversely, data for LV mass, a derived variable, reported LoA values of ± 15 g (10%) between phases. The LoA were consistent between EU and COC. Variation in both measured and derived variables were within, or close to, accepted limits of measurement or biological error. It would seem that in studies assessing LV structure and function in women the influence of menstrual phase or oral contraceptive use is of minor significance.