The effect of long-term soccer training on left ventricular structure and function in elite male youth soccer players.

AIMS: Cardiac adaptations in elite, male adolescent youth soccer players have been demonstrated in relation to training status. The time course of these adaptations and the delineation of the influence of volatile growth phases from the training effect on these adaptations remain unclear. Consequently, the aims of the study were to evaluate the impact of 3 years of elite-level soccer training on changes in left ventricular (LV) structure and function in a group of highly trained elite youth male soccer players (SP) as they transitioned through the pre-to-adolescent phase of their growth. METHODS: Twenty-two male youth SP from the highest Level of English Premier League Academy U-12 teams were evaluated once a year for three soccer seasons as the players progressed from the U-12 to U-14 teams. Fifteen recreationally active control participants (CON) were also evaluated over the same 3-year period. Two-dimensional transthoracic echocardiography was used to quantify LV structure and function. RESULTS: After adjusting for the influence of growth and maturation, training-induced increases in Years 2 and 3 were noted for: LV end diastolic volume (LVEDV; p = 0.02) and LV end systolic volume (LVESV; p = 0.02) in the SP compared to CON. Training-induced decrements were noted for LV ejection fraction (LVEF; p = 0.006) and TDI-S' (p < 0.001). CONCLUSIONS: An increase in training volume (Years 2 and 3) were aligned with LV volumetric adaptations and decrements in systolic function in the SP that were independent from the influence of rapid somatic growth. Decrements in systolic function were suggestive of a functional reserve for exercise.

A scoping review of 'Pacing' for management of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): lessons learned for the long COVID pandemic.

BACKGROUND: Controversy over treatment for people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a barrier to appropriate treatment. Energy management or pacing is a prominent coping strategy for people with ME/CFS. Whilst a definitive definition of pacing is not unanimous within the literature or healthcare providers, it typically comprises regulating activity to avoid post exertional malaise (PEM), the worsening of symptoms after an activity. Until now, characteristics of pacing, and the effects on patients' symptoms had not been systematically reviewed. This is problematic as the most common approach to pacing, pacing prescription, and the pooled efficacy of pacing was unknown. Collating evidence may help advise those suffering with similar symptoms, including long COVID, as practitioners would be better informed on methodological approaches to adopt, pacing implementation, and expected outcomes. OBJECTIVES: In this scoping review of the literature, we aggregated type of, and outcomes of, pacing in people with ME/CFS. ELIGIBILITY CRITERIA: Original investigations concerning pacing were considered in participants with ME/CFS. SOURCES OF EVIDENCE: Six electronic databases (PubMed, Scholar, ScienceDirect, Scopus, Web of Science and the Cochrane Central Register of Controlled Trials [CENTRAL]) were searched; and websites MEPedia, Action for ME, and ME Action were also searched for grey literature, to fully capture patient surveys not published in academic journals. METHODS: A scoping review was conducted. Review selection and characterisation was performed by two independent reviewers using pretested forms. RESULTS: Authors reviewed 177 titles and abstracts, resulting in 17 included studies: three randomised control trials (RCTs); one uncontrolled trial; one interventional case series; one retrospective observational study; two prospective observational studies; four cross-sectional observational studies; and five cross-sectional analytical studies. Studies included variable designs, durations, and outcome measures. In terms of pacing administration, studies used educational sessions and diaries for activity monitoring. Eleven studies reported benefits of pacing, four studies reported no effect, and two studies reported a detrimental effect in comparison to the control group. CONCLUSIONS: Highly variable study designs and outcome measures, allied to poor to fair methodological quality resulted in heterogenous findings and highlights the requirement for more research examining pacing. Looking to the long COVID pandemic, our results suggest future studies should be RCTs utilising objectively quantified digitised pacing, over a longer duration of examination (i.e. longitudinal studies), using the core outcome set for patient reported outcome measures. Until these are completed, the literature base is insufficient to inform treatment practises for people with ME/CFS and long COVID.

Habitual exercise influences carotid artery strain and strain rate, but not cognitive function in healthy middle-aged females.

PURPOSE: Aging females are at risk of declining vascular and cognitive function. Exercise can augment both factors independently; however, the influence of exercise on their interdependence is less clearly understood. Ultrasound speckle tracking is a sensitive novel measure of arterial aging but has not previously been used in middle-aged females. We aimed to elucidate the potential interactions between vascular and cognitive variables in active aging females. METHODS: Twelve active (56 ± 5 years; [Formula: see text]: 34.5 ± 6.1 ml.kg.min-1) and 13 inactive (57 ± 4 years; 22.8 ± 2.6 ml.kg.min-1) healthy middle-aged females were included. Ultrasound speckle tracking assessed short-axis common carotid artery (CCA) compliance via peak circumferential strain (PCS) and strain rate (PSR) at rest, during, and after 3-min isometric handgrip exercise. Flow-mediated dilation (FMD) of the brachial artery was assessed using ultrasound. Cognitive function was measured using Verbal Fluency, Trail Making, Stroop, and Digit Span tests. RESULTS: PCS (P = 0.003) and PSR (P = 0.004), were higher in the active cohort. FMD was similar between groups (P > 0.05). Minimal differences in cognitive function existed between groups, although the inactive group performed better in one test of animal Verbal Fluency (P < 0.01). No associations were observed between PCS, PSR, or FMD with cognitive function (all P > 0.05). CONCLUSION: This is the first study to assess PCS and PSR in middle-aged females and demonstrates that active middle-aged females exhibit a superior carotid artery profile compared to their inactive counterparts. However, PCS and PSR of the carotid artery may not be linked with cognitive function in middle-aged females.

Effect of supervision and athlete age and sex on exercise-based injury prevention programme effectiveness in sport: A meta-analysis of 44 studies.

We aimed to evaluate the influence of supervision, athlete age and sex and programme duration and adherence on exercise-based injury prevention programme effectiveness in sport. Databases were searched for randomized controlled trials evaluating exercise-based injury prevention programme effectiveness compared to "train-as-normal". A random effects meta-analysis for overall effect and pooled effects by sex and supervision and meta-regression for age, intervention duration and adherence were performed. Programmes were effective overall (risk ratio (RR) 0.71) and equally beneficial for female-only (0.73) and male-only (0.65) cohorts. Supervised programmes were effective (0.67), unlike unsupervised programmes (1.04). No significant association was identified between programme effectiveness and age or intervention duration. The inverse association between injury rate and adherence was significant (ß=-0.014, p = 0.004). Supervised programmes reduce injury by 33%, but there is no evidence for the effectiveness of non-supervised programmes. Females and males benefit equally, and age (to early middle age) does not affect programme effectiveness.

Effect of long-term soccer training on changes in cardiac function during exercise in elite youth soccer players.

It is unclear what the effect of long-term, high-volume soccer training has on left ventricular (LV) function during exercise in youth soccer players. This study evaluated changes in LV function during submaximal exercise in a group of highly trained male soccer players (SP) as they transitioned over a three-year period from pre-adolescent to adolescent athletes. Data were compared to age- and sex-matched recreationally active controls (CON) over the same time period. Twenty-two SP from two professional English Premier League youth soccer academies (age: 12.0 ± 0.3 years at start of the study) and 15 CON (age: 11.7 ± 0.3 years) were recruited. Two-dimensional echocardiography was used to quantify LV function during exercise at the same submaximal metabolic load (approx. 45%VO2peak ) across the 3 years. After controlling for growth and maturation, there were training-induced changes and superiority (p < 0.001) in cardiac index (QIndex) from year 1 in the SP compared to CON. SP (year 1: 6.13 ± 0.76; year 2: 6.94 ± 1.31; and year 3: 7.20 ± 1.81 L/min/m2 ) compared to CON (year 1: 5.15 ± 1.12; year 2: 4.67 ± 1.04; and year 3: 5.49 ± 1.06 L/min/m2 ). Similar training-induced increases were noted for mitral inflow velocity (E): SP (year 1: 129 ± 12; year 2: 143 ± 16; and year 3: 135 ± 18 cm/s) compared to CON (year 1: 113 ± 10; year 2: 111 ± 12; and year 3: 121 ± 9 cm/s). This study indicated that there was evidence of yearly, training-induced increases in left ventricular function during submaximal exercise independent from the influence of growth and maturation in elite youth SP.

The influence of training status on right ventricular morphology and segmental strain in elite pre-adolescent soccer players.

Cardiac modifications to training are a product of the genetic pre-disposition for adaptation and the repetitive haemodynamic loads that are placed on the myocardium. Elite pre-adolescent athletes are exposed to high-intensity training at a young age with little understanding of the physiological and clinical consequences. It is unclear how right ventricular (RV) structure and function may respond to this type of stimulus. The aim of this study was to compare RV structure and strain across the cardiac cycle and within individual segments in elite soccer players (SP) and controls (CON). METHODS: Twenty-two highly trained, male pre-adolescent SP and 22 age-and sex-matched recreationally active individuals CON were investigated using 2D echocardiography, including myocardial speckle tracking to assess basal, mid-wall, apical and global longitudinal strain and strain rate during systole (SRS) and diastole (SRE and SRA). RESULTS: greater RV cavity size was identified in the SP compared to CON (RVD1 SP: 32.3 ± 3.1 vs. CON: 29.6 ± 2.8 (mm/m2)0.5; p = 0.005). No inter-group differences were noted for peak global RV strain (SP: - 28.6 ± 4.9 vs CON: - 30.3 ± 4.0%, p = 0.11). Lower mid-wall strain was demonstrated in the SP compared to CON (SP: - 27.9 ± 5.8 vs. CON: - 32.2 ± 4.4%, p = 0.007). CONCLUSION: Soccer training has the potential to increase RV size in pre-adolescent players. The unique segmental analyses used in this study have identified inter-group differences that were masked by global strain evaluations. The clinical and physiological implications of these findings warrant further investigation.

Sex differences in heel pad stiffness during in vivo loading and unloading.

Due to conflicting data from previous studies a new methodological approach to evaluate heel pad stiffness and soft tissue deformation has been developed. The purpose of this study was to compare heel pad (HP) stiffness in both limbs between males and females during a dynamic unloading and loading activity. Ten males and 10 females volunteered to perform three dynamic trials to unload and load the HP. The dynamic protocol consisted of three continuous phases: foot flat (baseline phase), bilateral heel raise (unloading phase) and foot flat (loading phase) with each phase lasting two seconds. Six retroreflective markers (3 mm) were attached to the skin of the left and right heels using a customised marker set. Three-dimensional motion analysis cameras synchronised with force plates collected the kinematic and kinetic data throughout the trials. Three-way repeated measures ANOVA together with a Bonferroni post hoc test were applied to the stiffness and marker displacement datasets. On average, HP stiffness was higher in males than females during the loading and unloading phases. ANOVA results revealed no significant differences for the stiffness and displacement outputs with respect to sex, sidedness or phase interactions (p > .05) in the X, Y and Z directions. Irrespective of direction, there were significant differences in stiffness between the baseline and unloading conditions (p < .001) but no significant differences between the baseline and loaded conditions (p = 1.000). Post hoc analyses for the marker displacement showed significant differences between phases for the X and Z directions (p < .032) but no significant differences in the Y direction (p > .116). Finally, females portrayed lower levels of mean HP stiffness whereas males had stiffer heels particularly in the vertical direction (Z) when the HP was both unloaded and loaded. High HP stiffness values and very small marker displacements could be valuable indicators for the risk of pathological foot conditions.

Long-term athletic training does not alter age-associated reductions of left-ventricular mid-diastolic lengthening or expansion at rest.

PURPOSE: The interaction of ageing and exercise training status on left-ventricular (LV) peak strain is unclear. Additionally, strain analysis across the entire cardiac cycle facilitates a more detailed assessment of deformation, yet this has not been implemented to characterize the ageing LV and in association with training status. This study investigated healthy ageing and training status on LV systolic and diastolic strain utilizing novel echocardiographic applications. METHODS: Forty healthy males were included and allocated into four groups; young recreationally active (YRA, n = 9; 28 ± 5 years), old recreationally active (ORA, n = 10; 68 ± 6), young trained (YT, n = 10; 27 ± 6 years), and old trained (OT, n = 11, 64 ± 4 years) groups. Two-dimensional speckle-tracking echocardiography was performed to ascertain peak LV longitudinal and circumferential strain (base and apex) strain within each myocardial layer and at 5% increments across the cardiac cycle. RESULTS: Older groups had lower diastolic longitudinal lengthening and circumferential expansion between 40-85% mid-diastole, regardless of training status (P < 0.05). Whereas, strain throughout systole was similar between groups (P > 0.05). Longitudinal and circumferential (base and apex) peak and layer-specific strain did not differ between groups (P > 0.05). CONCLUSION: Novel applications of diastolic strain revealed lower age-associated LV longitudinal lengthening and circumferential expansion in older age. Yet, diastolic strain profiles did not differ based on chronic habits of exercise training and, thus, older trained men did not demonstrate an attenuation of age-associated differences in mid-diastolic LV strain.

The effect of varying intensities of lower limb eccentric muscle contractions on left ventricular function.

PURPOSE: The effect of eccentric (ECC) resistance exercise (RE) on myocardial mechanics is currently unknown. METHOD: This study investigated ECC RE at varying intensities on left ventricular (LV) function using LV strain (ε), wall stress and haemodynamic parameters. Twenty-four healthy male volunteers completed ECC leg extensions at 20%, 50% and 80% of their ECC maximal voluntary contraction (MVC), whilst receiving echocardiograms. Global longitudinal ɛ, strain rate (SR), longitudinal tissue velocity, heart rate (HR), blood pressure (BP), mean arterial pressure (MAP), LV wall stress and rate pressure product (RPP) were assessed at baseline and during exercise. RESULTS: Left ventricular global ɛ, systolic SR and wall stress remained unchanged throughout. Systolic blood pressure (sBP), MAP and RPP increased at 80% and 50% intensities compared to rest (P < 0.01). Eccentric RE increased HR and peak late diastolic SR at all intensities compared to rest (P < 0.02). CONCLUSION: The findings suggest acute ECC RE may not alter main parameters of LV function, supporting future potential for wider clinical use. However, future studies must investigate the impact of multiple repetitions and training on LV function.

Dietary nitrate supplementation alters the oral microbiome but does not improve the vascular responses to an acute nitrate dose.

Nitrate (NO3-) contained in food and beverages can transiently increase nitric oxide (NO) availability following a stepwise reduction to nitrite (NO2-) by commensal bacteria in the oral cavity. We tested the hypothesis that regular ingestion of dietary NO3- would influence the oral microbiome, the capacity to reduce NO3- to NO2- in saliva, and the vascular responses to an acute dose of NO3-. The abundance of bacterial species on the tongue, the availability of NO markers, and vascular function were assessed in 11 healthy males before and after 7 days of supplementation with NO3--rich beetroot juice and a NO3--depleted placebo. As expected, saliva and plasma NO2- and NO3- were significantly elevated after NO3- supplementation (all P < 0.05) but not placebo. We found that NO3- supplementation increased salivary pH (7.13 ±â€¯0.54 to 7.39 ±â€¯0.68, P = 0.043) and altered the abundance of some bacteria previously implicated in NO3- reduction: Neisseria (from 2% ±â€¯3%-9% ±â€¯5%, P < 0.001), Prevotella (from 34% ±â€¯17%-23% ±â€¯11%, P = 0.001) and Actinomyces (from 1% ±â€¯1%-0.5% ±â€¯0.4%). Despite these alterations to the oral microbiota, an acute dose of NO3- increased salivary and plasma NO2-, reduced systolic blood pressure and increased the response to flow mediated dilation to a similar extent before and after 7 days of supplementation (P > 0.05). Our study establishes that supplementing the diet with NO3- for a sustained period can alter the oral environment in favour of health but does not impact the response to an acute NO3- dose. Acute ingestion of NO3- results in transient improvements in vascular function but the dietary induced adaptations to the oral bacteria did not enhance these effects.

Variability in nitrate-reducing oral bacteria and nitric oxide metabolites in biological fluids following dietary nitrate administration: An assessment of the critical difference.

There is conflicting evidence on whether dietary nitrate supplementation can improve exercise performance. This may arise from the complex nature of nitric oxide (NO) metabolism which causes substantial inter-individual variability, within-person biological variation (CVB), and analytical imprecision (CVA) in experimental endpoints. However, no study has quantified the CVA and CVB of NO metabolites or the factors that influence their production. These data are important to calculate the critical difference (CD), defined as the smallest difference between sequential measurements required to signify a true change. The main aim of the study was to evaluate the CVB, CVA, and CD for markers of NO availability (nitrate and nitrite) in plasma and saliva before and after the ingestion of nitrate-rich beetroot juice (BR). We also assessed the CVB of nitrate-reducing bacteria from the dorsal surface of the tongue. It was hypothesised that there would be substantial CVB in markers of NO availability and the abundance of nitrate-reducing bacteria. Ten healthy male participants (age 25 ±â€¯5 years) completed three identical trials at least 6 days apart. Blood and saliva were collected before and after (2, 2.5 and 3 h) ingestion of 140 ml of BR (∼12.4 mmol nitrate) and analysed for [nitrate] and [nitrite]. The tongue was scraped and the abundance of nitrate-reducing bacterial species were analysed using 16S rRNA next generation sequencing. There was substantial CVB for baseline concentrations of plasma (nitrate 11.9%, nitrite 9.0%) and salivary (nitrate 15.3%, nitrite 32.5%) NO markers. Following BR ingestion, the CVB for nitrate (plasma 3.8%, saliva 12.0%) and salivary nitrite (24.5%) were lower than baseline, but higher for plasma nitrite (18.6%). The CD thresholds that need to be exceeded to ensure a meaningful change from baseline are 25, 19, 37, and 87% for plasma nitrate, plasma nitrite, salivary nitrate, and salivary nitrite, respectively. The CVB for selected nitrate-reducing bacteria detected were: Prevotella melaninogenica (37%), Veillonella dispar (35%), Haemophilus parainfluenzae (79%), Neisseria subflava (70%), Veillonella parvula (43%), Rothia mucilaginosa (60%), and Rothia dentocariosa (132%). There is profound CVB in the abundance of nitrate-reducing bacteria on the tongue and the concentration of NO markers in human saliva and plasma. Where these parameters are of interest following experimental intervention, the CD values presented in this study will allow researchers to interpret the meaningfulness of the magnitude of the change from baseline.

Sprint Interval Training and the School Curriculum: Benefits Upon Cardiorespiratory Fitness, Physical Activity Profiles, and Cardiometabolic Risk Profiles of Healthy Adolescents.

BACKGROUND: This study examined the impact of a 4-week school-based sprint interval training program on cardiorespiratory fitness (CRF), daily physical activity (PA) behavior, and cardiometabolic risk (CMR) outcomes in adolescents. METHODS: A total of 56 adolescents (22 females) were allocated to either an intervention (n = 22; 17.0 [0.3] y) or control group (n = 30; 16.8 [0.5] y). Intervention group performed 5 to 6, 30 second "all out" running sprints, interspersed with 30-second rest intervals, 3 times per week, for 4 consecutive weeks, whereas control group performed their normal physical education lessons. CRF was estimated from the 20-m multistage fitness test and PA behavior was determined using accelerometry. Fasting blood samples were obtained to measure biochemical markers of CMR. RESULTS: Significant group × time interactions were observed for CRF (5.03 [1.66 to 8.40]; P < .001; d = 0.95), sedentary time (136.15 [91.91 to 180.39]; P = .004; d = 1.8), moderate PA (57.20 [32.17 to 82.23]; P < .001; d = 1.5), vigorous PA (5.40 [4.22 to 6.57]; P < .001; d = 1.2), fasting insulin (0.37 [-0.48 to 1.21]; P = .01; d = 1.0), homeostasis model of assessment-insulin resistance (0.26 [0.15 to 0.42]; P < .001; d = 0.9), and clustered CMR score (0.22 [-0.05 to 0.68]; P < .001; d = 10.63). CONCLUSION: Findings of this study indicate that 4 weeks of school-based sprint interval training improves CRF, improves PA profiles, and maintains CMR in adolescents during the school term.

Global and regional left ventricular circumferential strain during incremental cycling and isometric knee extension exercise.

BACKGROUND: The objective of this study was to investigate left ventricular (LV) circumferential strain responses to incremental cycling and isometric knee extension exercises. METHODS: Twenty-six healthy male participants (age = 30 ± 6 years) were used to study LV global (GCS) and regional circumferential strain at the apex (ACS) and base (BCS) during incremental cycling at 30% and 60% work rate maximum (Wmax ) and short-duration (15 seconds contractions) isometric knee extensions at 40% and 75% maximum voluntary contraction (MVC) using two-dimensional speckle tracking echocardiography. RESULTS: During cycling (n = 22), GCS increased progressively from rest to 60% Wmax (-22.85 ± 3.26% to -29.87 ± 2.59%, P < .01). ACS increased from rest to 30% Wmax (-26.29 ± 4.84% to -36.84 ± 6.94%, P < .01) and then remained unchanged to 60% Wmax (-40.72 ± 4.06%, P = .068). BCS decreased from rest to 30% Wmax (-19.41 ± 2.79 to -17.51 ± 4.66%, P = .05) and then remained unchanged to 60% Wmax . During isometric knee extension (n = 23), GCS decreased from rest to 40% MVC (-22.63 ± 3.46 to -20.10 ± 2.78%, P < .05) and then remained unchanged to 75% MVC. Similarly, BCS decreased from rest to 40% MVC (-19.21 ± 2.58% to -13.55 ± 3.45%, P < .01) and then remained unchanged, whereas ACS did not change with exercise intensity (rest, -26.05 ± 5.34%; 40% MVC, -26.64 ± 4.53% and 75% MVC -27.22 ± 5.34%, all P > .05). CONCLUSION: Global circumferential strain increased stepwise during incremental cycling, mediated by the apex with trivial changes at the base. In contrast, GCS decreased during the isometric knee extension to 40% MVC and then plateaued, due to decreased BCS as ACS was maintained. A novel finding is that the GCS response appears to be exercise modality dependant and is the consequence of region-specific changes.

High-intensity interval training (HIIT) increases insulin-like growth factor-I (IGF-I) in sedentary aging men but not masters' athletes: an observational study.

INTRODUCTION: The aim of this investigation was to examine the impact high-intensity interval training (HIIT) on serum insulin-like growth factor-I (IGF-I) in active compared with sedentary aging men. METHODS: 22 lifetime sedentary (SED; 62 ± 2 years) and 17 masters' athletes (LEX; 60 ± 5 years) were recruited to the study. As HIIT requires preconditioning exercise in sedentary cohorts, the study required three assessment phases; enrollment (phase A), following preconditioning exercise (phase B), and post-HIIT (phase C). Serum IGF-I was determined by electrochemiluminescent immunoassay. RESULTS: IGF-I was higher in LEX compared to SED at baseline (p = 0.007, Cohen's d = 0.91), and phase B (p = 0.083, Cohen's d = 0.59), with only a small difference at C (p = 0.291, Cohen's d = 0.35). SED experienced a small increase in IGF-I following preconditioning from 13.1 ± 4.7 to 14.2 ± 6.0 µg·dl-1 (p = 0.376, Cohen's d = 0.22), followed by a larger increase post-HIIT (16.9 ± 4.4 µg·dl-1), which was significantly elevated compared with baseline (p = 0.002, Cohen's d = 0.85), and post-preconditioning (p = 0.005, Cohen's d = 0.51). LEX experienced a trivial changes in IGF-I from A to B (18.2 ± 6.4 to 17.2 ± 3.7 µg·dl-1 [p = 0.538, Cohen's d = 0.19]), and a small change post-HIIT (18.4 ± 4.1 µg·dl-1 [p = 0.283, Cohen's d = 0.31]). Small increases were observed in fat-free mass in both groups following HIIT (p < 0.05, Cohen's d = 0.32-0.45). CONCLUSIONS: In conclusion, HIIT with preconditioning exercise abrogates the age associated difference in IGF-I between SED and LEX, and induces small improvements in fat-free mass in both SED and LEX.

Utility of three anthropometric indices in assessing the cardiometabolic risk profile in children.

OBJECTIVES: To evaluate the ability of BMI, WC, and WHtR to identify increased cardiometabolic risk in pre-adolescents. METHODS: This is a cross-sectional study involving 192 children (10.92 ± 0.58 years, 56% female) from the United Kingdom between 2010 and 2013. Receiver operating characteristic curves determined the discriminatory ability of BMI, WC and WHtR to identify individuals with increased cardiometabolic risk (increased clustered triglycerides, HDL-cholesterol, systolic blood pressure, cardiorespiratory fitness, and glucose). RESULTS: A WHtR ≥ 0.5 increased the odds by 5.2 (95% confidence interval 2.6 - 10.3) of having increased cardiometabolic risk. Similar associations were observed for BMI and WC. Both BMI-z and WHtR were fair predictors of increased cardiometabolic risk, although BMI-z demonstrated the best trade-off between sensitivity and specificity, 76.1% and 63.6%, compared with 68.1% and 65.5% for WHtR. Cross-validation analysis revealed that BMI-z and WHtR correctly classified 84% of individuals (kappa score = 0.671, 95% CI 0.55, 0.79). The sensitivity of the cut-points suggests that 89.3% of individuals were correctly classified as being at risk with only 10.7% misdiagnosed whereas the specificity of the cut-points indicated that 77.8% of individuals were correctly identified as being healthy with 22.2% of individuals incorrectly diagnosed as being at risk. CONCLUSIONS: Findings suggest that WHtR provides similar cardiometabolic risk estimates to age and sex adjusted BMI.

Left ventricular twist mechanics during incremental cycling and knee extension exercise in healthy men.

PURPOSE: The objective of the present study was to investigate left ventricular (LV) twist mechanics in response to incremental cycling and isometric knee extension exercises. METHODS: Twenty-six healthy male participants (age = 30.42 ± 6.17 years) were used to study peak twist mechanics at rest and during incremental semi-supine cycling at 30 and 60% work rate maximum (W max) and during short duration (15 s contractions) isometric knee extension at 40 and 75% maximum voluntary contraction (MVC), using two-dimensional speckle tracking echocardiography. RESULTS: Data presented as mean ± standard deviation or median (interquartile range). LV twist increased from rest to 30% W max (13.21° ± 4.63° to 20.04° ± 4.76°, p < 0.001) then remained unchanged. LV systolic and diastolic twisting velocities progressively increased with exercise intensity during cycling from rest to 60% W max (twisting, 88.21° ± 20.51° to 209.05° ± 34.56° s-1, p < 0.0001; untwisting, -93.90 (29.62)° to -267.31 (104.30)° s-1, p < 0.0001). During the knee extension exercise, LV twist remained unchanged with progressive intensity (rest 13.40° ± 4.80° to 75% MVC 16.77° ± 5.54°, p > 0.05), whilst twisting velocity increased (rest 89.15° ± 21.77° s-1 to 75% MVC 124.32° ± 34.89° s-1, p < 0.01). Untwisting velocity remained unchanged from rest [-90.60 (27.19)° s-1] to 40% MVC (p > 0.05) then increased from 40 to 75% MVC [-98.44 (43.54)° s-1 to -138.42 (73.29)° s-1, p < 0.01]. Apical rotations and rotational velocities were greater than basal during all conditions and intensities (all p < 0.01). CONCLUSION: Cycling increased LV twist to 30% W max which then remained unchanged thereafter, whereas twisting velocities showed further increases to greater intensities. A novel finding is that LV twist was unaffected by incremental knee extension, yet systolic and diastolic twisting velocities augmented with isometric exercise.

Strength adaptation to squat exercise is different between Caucasian and South Asian novice exercisers.

This study compared the progression of muscular strength (MS) adaptation between age-matched Caucasian (CAUC) and South Asian (SOU) men during 6 weeks (3× week-1) of resistance training. MS was determined pre and post intervention by 3-repetition maximum (3RM) strength tests, and data were analysed using repeated measures ANOVA. Pre-intervention upper and lower body 3RM were similar between groups and both upper and lower body 3RM increased in CAUCs (P < .001) and SOUs (P < .001) following resistance training. However, lower body strength adaptation (3RM) was higher in CAUCs compared with SOUs (P = .002). There was a significant group × time interaction in strength progression of the squat exercise (P = 0.03) from session 7 through to 18 (completion). The present study offers novel but provisional data that lower body strength adaptation is slower in SOU than CAUC men despite comparable adaptation to upper body strength.

Testosterone enables growth and hypertrophy in fusion impaired myoblasts that display myotube atrophy: deciphering the role of androgen and IGF-I receptors.

We have previously highlighted the ability of testosterone (T) to improve differentiation and myotube hypertrophy in fusion impaired myoblasts that display reduced myotube hypertrophy via multiple population doublings (PD) versus their parental controls (CON); an observation which is abrogated via PI3K/Akt inhibition (Deane et al. 2013). However, whether the most predominant molecular mechanism responsible for T induced hypertrophy occurs directly via androgen receptor or indirectly via IGF-IR/PI3K/Akt pathway is currently debated. PD and CON C2C12 muscle cells were exposed to low serum conditions in the presence or absence of T (100 nM) ± inhibitors of AR (flutamide/F, 40 µm) and IGF-IR (picropodophyllin/PPP, 150 nM) for 72 h and 7 days (early/late muscle differentiation respectively). T increased AR and Akt abundance, myogenin gene expression, and myotube hypertrophy, but not ERK1/2 activity in both CON and PD cell types. Akt activity was not increased significantly in either cell type with T. Testosterone was also unable to promote early differentiation in the presence of IGF-IR inhibitor (PPP) yet still able to promote appropriate later increases in myotube hypertrophy and AR abundance despite IGF-IR inhibition. The addition of the AR inhibitor powerfully attenuated all T induced increases in differentiation and myotube hypertrophy with corresponding reductions in AR abundance, phosphorylated Akt, ERK1/2 and gene expression of IGF-IR, myoD and myogenin with increases in myostatin mRNA in both cell types. Interestingly, despite basally reduced differentiation and myotube hypertrophy, PD cells showed larger T induced increases in AR abundance vs. CON cells, a response abrogated in the presence of AR but not IGF-IR inhibitors. Furthermore, T induced increases in Akt abundance were sustained despite the presence of IGF-IR inhibition in PD cells only. Importantly, flutamide alone reduced IGF-IR mRNA in both cell types across time points, with an observed reduction in activity of ERK and Akt, suggesting that IGF-IR was transcriptionally regulated by AR. However, where testosterone increased AR protein content there was no increases observed in IGF-IR gene expression. This suggested that sufficient AR was important to enable normal IGF-IR expression and downstream signalling, yet elevated levels of AR due to testosterone had no further effect on IGF-IR mRNA, despite testosterone increasing Akt abundance in the presence of IGF-IR inhibitor. In conclusion, testosterones ability to improve differentiation and myotube hypertrophy occurred predominately via increases in AR and Akt abundance in both CON and PD cells, with fusion impaired cells (PD) showing an increased responsiveness to T induced AR levels. Finally, T induced increases in myotube hypertrophy (but not early differentiation) occurred independently of upstream IGF-IR input, however it was apparent  that normal AR function in basal conditions was required for adequate IGF-IR gene expression and downstream ERK/Akt activity.

Acute whole body UVA irradiation combined with nitrate ingestion enhances time trial performance in trained cyclists.

Dietary nitrate supplementation has been shown to increase nitric oxide (NO) metabolites, reduce blood pressure (BP) and enhance exercise performance. Acute exposure to ultraviolet (UV)-A light also increases NO bioavailability and reduces BP. We conducted a randomized, counterbalanced placebo-controlled trial to determine the effects of UV-A light alone and in combination with nitrate on the responses to sub-maximal steady-state exercise and time trial (TT) performance. Nine cyclists (VO2max 53.1 ± 4.4 ml/kg/min) completed five performance trials comprising 10 min submaximal steady-state cycling followed by a 16.1 km TT. Following a familiarization the final four trials were preceded, in random order, by either (1) Nitrate gels (NIT) + UV-A, (2) Placebo (PLA) + UV-A, (3) NIT + Sham light (SHAM) and (4) PLA + SHAM (control). The NIT gels (2 × 60 ml gels, ~8.1 mmol nitrate) or a low-nitrate PLA were ingested 2.5 h prior to the trial. The light exposure consisted of 20 J/cm(2) whole body irradiation with either UV-A or SHAM light. Plasma nitrite was measured pre- and post-irradiation and VO2 was measured continuously during steady-state exercise. Plasma nitrite was higher for NIT + SHAM (geometric mean (95% CI), 332 (292-377) nM; P = 0.029) and NIT + UV-A (456 (312-666) nM; P = 0.014) compared to PLA + SHAM (215 (167-277) nM). Differences between PLA + SHAM and PLA + UV-A (282 (248-356) nM) were small and non-significant. During steady-state exercise VO2 was reduced following NIT + UVA (P = 0.034) and tended to be lower in NIT + SHAM (P = 0.086) but not PLA + UV-A (P = 0.381) compared to PLA + SHAM. Performance in the TT was significantly faster following NIT + UV-A (mean ± SD 1447 ± 41 s P = 0.005; d = 0.47), but not PLA + UV-A (1450 ± 40 s; d = 0.41) or NIT + SHAM (1455 ± 47 s; d = 0.28) compared to PLA + SHAM (1469 ± 52 s). These findings demonstrate that exposure to UV-A light alone does not alter the physiological responses to exercise or improve performance in a laboratory setting. A combination of UV-A and NIT, however, does improve cycling TT performance in this environment, which may be due to a larger increase in NO availability.

Six weeks of conditioning exercise increases total, but not free testosterone in lifelong sedentary aging men.

INTRODUCTION: Advancing age is associated with a gradual decline in circulating androgens, and the putative role of exercise training on systemic androgens remains to be adequately defined. METHODS: The present investigation examined the impact of 6 weeks of supervised exercise training on resting levels of systemic hormones in a cohort of lifelong sedentary men [SED (n = 28), 62.5 ± 5.3 years], compared with a positive control group of age-matched lifelong exercisers [LE (n = 20), 60.4 ± 4.7 years, >30 years training history]. Blood hormones were sampled pre- and post-intervention from an antecubital forearm vein and analysed using electrochemiluminescent immunoassay. Cardiorespiratory fitness ([Formula: see text]) was determined via indirect calorimetry during an incremental cycle test to volitional exhaustion. RESULTS: Analysis of variance (ANOVA) revealed a lack of significant change in any parameter amongst LE, whilst SED experienced a significant exercise-induced improvement in cardiorespiratory fitness and total testosterone (all p < 0.05). Concurrent increases in sex hormone-binding globulin (SHBG; p < 0.05) resulted in a lack of change to either bioavailable or calculated free testosterone (p > 0.05) amongst SED. CONCLUSIONS: Although resting levels of systemic total testosterone increased in response to 6 weeks of exercise training, increases in SHBG negated any potential relationship between calculated-free or bioavailable testosterone. These findings indicate that increases in bioavailable testosterone fraction are not required for cardiorespiratory fitness improvements in aging men.