Arterial stiffness responses to prolonged sitting combined with a high-glycemic-index meal: a double-blind, randomized crossover trial.

Regular exposure to uninterrupted prolonged sitting and the consumption of high-glycemic-index (HGI) meals is independently associated with increased cardiovascular disease risk. Sitting for as little as 1 h can impair the health of both peripheral and central arteries. However, it is currently unknown whether combined acute exposure to uninterrupted prolonged sitting and an HGI meal is more detrimental to global (peripheral and central) vascular health. The purpose of this study was to investigate the effect of prolonged sitting (3 h), following the consumption of an HGI or a low-glycemic-index (LGI) meal, on global pulse wave velocity (G-PWV). Eighteen healthy participants [70% female, mean (standard deviation, SD) age = 22.6 (3.1) yr, body mass index (BMI) = 25.5 (6.1) kg/m2] sat for 3 h after consuming an HGI or LGI meal. G-PWV was assessed by incorporating three PWV measures (carotid-femoral, brachial-femoral, and femoral-ankle). The effects of time (PRE vs. POST) and condition (LGI vs. HGI) were analyzed using linear mixed models. Following prolonged sitting, G-PWV increased by 0.29 m/s (i.e., PRE vs. POST). However, the condition (P = 0.987) and time × condition (P = 0.954) effects were nonsignificant. The current findings support previous research showing an increase in arterial stiffness with prolonged sitting. However, in young and healthy adults, the arterial stiffness response was not worsened through HGI meal consumption.NEW & NOTEWORTHY We used novel statistical techniques and study design characteristics to examine how the cardiovascular disruptions due to prolonged sitting are changed after the consumption of low- and high-glycemic-index meals. The current study indicates that changes in arterial stiffness due to prolonged sitting are not worsened in young, healthy adults after the consumption of a high-glycemic-index meal.

Carotid artery wall mechanics in young males with high cardiorespiratory fitness.

NEW FINDINGS: What is the central question of this study? Common carotid artery (CCA) two-dimensional strain imaging detects intrinsic arterial wall properties beyond conventional measures of arterial stiffness, but the effect of cardiorespiratory fitness on two-dimensional strain-derived indices of CCA stiffness is unknown. What is the main finding and its importance? Two-dimensional strain imaging of the CCA revealed greater peak circumferential strain and systolic strain rate in highly fit men compared with their less fit counterparts. Altered CCA wall mechanics might reflect intrinsic training-induced adaptations that help to buffer the increase in pulse pressure and stroke volume during exercise. ABSTRACT: The influence of cardiorespiratory fitness on arterial stiffness in young adults remains equivocal. Beyond conventional measures of arterial stiffness, two-dimensional strain imaging of the common carotid artery (CCA) provides new information related to the intrinsic properties of the arterial wall. Therefore, the aim of this study was to assess the effect of cardiorespiratory fitness on both conventional indices of CCA stiffness and two-dimensional strain parameters, at rest and after a bout of aerobic exercise in young, healthy men. Short-axis ultrasound images of the CCA were recorded in 34 healthy men {22 years old [95% confidence interval (CI), 19, 22]} before and immediately after 5 min of aerobic exercise (40% of maximal oxygen consumption). Images were analysed for arterial diameter, peak circumferential strain (PCS) and peak systolic and diastolic strain rates (S-SR and D-SR). Heart rate, systolic and diastolic blood pressure were simultaneously assessed, and Peterson's elastic modulus (Ep ) and ß-stiffness (ß1 ) were calculated. Participants were separated post hoc into moderate- and high-fitness groups [maximal oxygen consumption, 48.9 (95% CI, 44.7, 53.2) versus 65.6 ml kg-1  min-1 (95% CI, 63.1, 68.1), respectively; P < 0.001]. The Ep and ß1 were similar between groups at baseline (P > 0.13) but were elevated in the moderate-fitness group postexercise (P < 0.04). The PCS and S-SR were elevated in the high-fitness group at both time points [3.0% (95% CI, 1.2, 4.9), P = 0.002, and 0.401 s-1 (95% CI, 0.085, 0.72), P = 0.02, respectively]. No group differences were observed in CCA heart rate, systolic or diastolic blood pressure or D-SR throughout the protocol (P > 0.05). Highly fit individuals exhibit elevated CCA, PCS and S-SR, which might reflect training-induced adaptations that help to buffer the increase in pulse pressure and stroke volume during exercise.

The validity and reliability of continuous-wave near-infrared spectroscopy for the assessment of leg blood volume during an orthostatic challenge.

UNLABELLED: Near-infrared spectroscopy (NIRS) can potentially be used to assess the cardiovascular autonomic system by monitoring orthostatic challenge-induced shifts in lower limb blood volume. However, in order to be of clinical utility the test must be valid, reliable, and relatively simple to conduct. PURPOSE: To induce lower limb blood volume shifts using a 10 min 70° head-up tilt, and: (1) in the soleus, determine the validity of an inexpensive continuous wave (cw)-NIRS device by comparing to a criterion frequency-domain (fd-) NIRS device, (2) determine the between-day reliability of soleus assessments obtained from cw-NIRS and fd-NIRS; and, (3) compare the between-day reliability for fd-NIRS assessments obtained at the soleus (standard) and gastrocnemius (simpler alternative). METHODS: Fifteen non-smoking healthy adults were tested on 3 different mornings, under standardized conditions, separated by a maximum of 7 days. Total haemoglobin concentration (tHb) was continuously monitored bi-laterally in the medial soleus using cw-NIRS and fd-NIRS. For site comparison, tHb was measured in the medial gastrocnemius using fd-NIRS. RESULTS: (1) The area under the curve (AUC) for cw-NIRS and fd-NIRS assessments at the soleus were not significantly different (p = 0.619). (2) The criterion (0.75) intra-class correlation coefficient (ICC) was exceeded for both cw-NIRS and fd-NIRS. (3) The criterion ICC was exceeded for both soleus and gastrocnemius assessments. CONCLUSION: Continuous-wave NIRS can be used to monitor orthostatic stress-induced shifts in lower leg blood volume with acceptable validity and reliability. This orthostatic test may present a relatively simple and inexpensive approach for assessing the cardiovascular autonomic nervous system.

The influence of playing surface on physiological and performance responses during and after soccer simulation.

The aim of this study was to investigate the effect of playing surface on physiological and performance responses during and in the 48 h after simulated soccer match play. Blood lactate, single-sprint, repeated-sprint and agility of eight amateur soccer players were assessed throughout a 90-min soccer-simulation protocol (SSP) completed on natural turf (NT) and artificial turf. Counter-movement jump, multiple-rebound jump, sprint (10 m, 60 m), L-agility run (L-AR), creatine kinase (CK) and perception of muscle soreness (PMS) were measured before, immediately after, 24 h and 48 h after exercise. Analyses revealed significant changes in blood lactate and single-sprint performance (both P < 0.05) during the SSP but with no significant differences between surfaces. Conversely, repeated-sprint performance demonstrated an interaction effect, with reductions in performance evident on NT only (P < 0.05). Whilst L-AR and 10-m sprint performance remained unchanged, 60-m sprint and multiple-rebound jump performance were impaired, and PMS and CK were elevated immediately following the SSP (all P < 0.05) but with no surface effects. Although performance, CK and PMS were negatively affected to some degree in the 48 h after the SSP, there was no surface effect. For the artificial and natural surfaces used in the present study, physiological and performance responses to simulated soccer match play appear to be similar. Whilst a potential for small differences in performance response exists during activity, surface type does not affect the pattern of recovery following simulated match play.

Development of a soccer simulation protocol to include repeated sprints and agility.

Existing procedures for the simulation of soccer match play fail to incorporate multidirectional and repeated-sprint activities, even though these movements are considered fundamental to match play. In the current study, selected physiological and performance responses were assessed during an adapted version of an existing soccer simulation protocol. Mean heart rates of 163 ± 14 beats·min-1, mean blood lactates of 4.9 ± 2.3 mmol·L-1 and decrements in single-sprint and repeated-sprint performances were observed. The presented adaptations to an existing soccer simulation protocol better reflect the movement characteristics as well as the physiological and performance responses of soccer match play.

The effect of 45 minutes of soccer-specific exercise on the performance of soccer skills.

PURPOSE: The aim of the study was to examine the effect of fatigue, developed during prolonged high-intensity intermittent exercise, on the performance of soccer shooting and dribbling skill. METHODS: Nine semiprofessional soccer players with a mean age of 20.7+/-1.4 years volunteered to participate in the study. Participants completed a slalom dribble test and the Loughborough Soccer Shooting Test (LSST), before and directly following the performance of three 15-min bouts of a modified version of the Loughborough Intermittent Shuttle Test (LIST). RESULTS: Mean heart rates and mean 15-m sprint times remained unchanged across the three bouts of the LIST. Following the LIST slalom dribbling time increased significantly by 4.5+/-4.0% (P=.009), while the mean total points scored during the LSST was significantly reduced by 7.6+/-7.0 points (P=.012). When fatigued the frequency of shots in the LSST achieving the highest score of 5 points was reduced by 47% while the frequency of shots achieving the lowest 0 point score increased by 85%. CONCLUSION: Results show that while 45 min of exercise caused no decrements in sprint performance there were significant reductions in the ability to perform soccer-specific skills. Both the speed (dribbling time) and accuracy (shot performance) with which soccer-specific skills were executed was impaired following exercise replicating one-half of a soccer match.