Impact of proximal and distal cuff inflation on brachial artery endothelial function in healthy individuals.

PURPOSE: In this study, we examined whether the decrease in endothelial function associated with short-term exposure to elevated retrograde shear rate (SR), could be prevented when combined with a concurrent drop in transmural pressure in humans. METHODS: Twenty-five healthy individuals reported to our laboratory on three occasions to complete 30-min experimental conditions, preceded and followed by assessment of endothelial function using flow-mediated dilation (FMD). We used cuff inflation for 30-min to manipulate retrograde SR and transmural pressure in the brachial artery. Subjects underwent, in randomised order: (1) forearm cuff inflation to 60 mmHg (distal cuff; causing increase in retrograde SR), (2) upper arm cuff inflation to 60 mmHg (proximal cuff; causing increase in retrograde SR + decrease in transmural pressure), and (3) no cuff inflation (Control). RESULTS: The distal and proximal cuff conditions both increased brachial artery retrograde SR (p < 0.001) and oscillatory shear index (p < 0.001). The Control intervention did not alter SR patterns or FMD (p > 0.05). A significant interaction-effect was found for FMD (p < 0.05), with the decrease during distal cuff (from 6.9 ± 2.3% to 6.1 ± 2.5%), being reversed to an increase with proximal cuff (from 6.3 ± 2.0 to 6.9 ± 2.0%). The proximal cuff-related increase in FMD could not be explained by the decrease in antegrade or increase in retrograde shear. CONCLUSION: This study suggests that a decrease in transmural pressure may ameliorate the decline in endothelial function that occurs following exposure to elevated retrograde shear in healthy individuals.

A whole family approach to childhood obesity management (GOALS): relationship between adult and child BMI change.

BACKGROUND: A growing body of evidence advocates a multidisciplinary, family-focused approach to childhood obesity management, but there is a need to explore familial factors associated with intervention success. AIM: This study explored the relationship between adult BMI change and child BMI SDS change following completion of a community-based, lifestyle change intervention for obese children and families (Getting Our Active Lifestyles Started (GOALS)). METHOD: Sixty of 121 families with overweight children completed the GOALS intervention between September 2006 and March 2009.Complete pre- and post-intervention (6 months) BMI data was available for 47 of these families, 26 of whom attended 12-month follow-up. Child BMI was converted to age- and sex-specific standard deviation scores (SDS) using the 1990 UK growth references. RESULTS: There was a strong correlation between adult BMI change and child BMI SDS change from pre- to post-intervention (r = 0.53, p < 0.001) and from pre-intervention to 12-month follow up (r = 0.72, p < 0.001). Over both time periods, children with adults who reduced BMI were more likely to reduce BMI SDS (p < 0.01) and showed a greater reduction in BMI SDS (p < 0.01) than children with adults who maintained or increased BMI. CONCLUSION: The results showed a strong positive association between adult BMI change and child BMI SDS change, particularly during the post-intervention period where therapeutic contact was minimal. The findings suggest active involvement of adult family members in the weight loss process improves child treatment outcomes.

The effectiveness of compression garments and lower limb exercise on post-exercise blood pressure regulation in orthostatically intolerant athletes.

OBJECTIVE: Orthostatic intolerance (OI) may occur postexercise in normotensive individuals due to gravitational stress and removal of muscle pump. DESIGN: Six subjects performed 3 maximal bouts of exercise associated with (1) no intervention (CONTROL) (initial trial), (2) with use of lower limb compression garment (TROU), and (3) lower limb exercise (HEEL). SETTING: In each trial, 10 minutes of supine rest was followed by 10 minutes of standing before and immediately after maximal exercise. PARTICIPANTS: All subjects were OI during the CONTROL trial. INTERVENTIONS: In the TROU trial, the compression garment was worn during the supine and standing phases. In the HEEL trial, heel raises were performed every 60 seconds during standing periods. MAIN OUTCOME MEASURES: Systolic blood pressure and heart rate were continuously recorded, and stroke, cardiac output, and total peripheral resistance were estimated (PortAPres, TNO Biomedical Instrumentation, Amsterdam, the Netherlands). Positional changes were compared preexercise and postexercise in CONTROL, TROU, and HEEL via 2-way analysis of variance. RESULTS: All 6 subjects experienced OI in the CONTROL trial, but this was reduced to 2 after the HEEL and 1 after the TROU. Minor increases in systolic blood pressure (CONTROL, 3 +/- 11; TROU, 12 +/- 18; HEEL, 7 +/- 15 mm Hg) and heart rate (CONTROL, 10 +/- 12; TROU, 16 +/- 8; HEEL, 15 +/- 13 beats.min) were observed, but total peripheral resistance did not alter significantly during orthostasis postexercise (CONTROL, 0.462 +/- 0.351; TROU, 0.325 +/- 0.212; HEEL, 0.746 +/- 0.412 medical units). CONCLUSIONS: It seems that simple methods/practices adopted by athletes can have a positive impact on OI.

The physiological cost and enjoyment of Wii Fit in adolescents, young adults, and older adults.

BACKGROUND: Active video games (exergames) increase energy expenditure (EE) and physical activity (PA) compared with sedentary video gaming. The physiological cost and enjoyment of exergaming in adolescents, and young and older adults has not been documented, nor compared with aerobic exercise. This study compared the physiological cost and enjoyment of exergaming on Wii Fit with aerobic exercise in 3 populations. METHODS: Cardiorespiratory and enjoyment measurements were compared in 14 adolescents, 15 young adults, and 13 older adults during handheld inactive video gaming, Wii Fit activities (yoga, muscle conditioning, balance, aerobics), and brisk treadmill walking and jogging. RESULTS: For all groups EE and heart rate (HR) of Wii Fit activities were greater than handheld gaming (P < .001) but lower than treadmill exercise (P

Influence of age, sex, and aerobic capacity on forearm and skin blood flow and vascular conductance.

This study investigated the influence of age, sex, and aerobic capacity on resting and peak forearm and cutaneous blood flow (FBF, CBF). We recruited 93 female and 129 male subjects (age range 16-76 years). FBF and CBF were assessed by plethysmography and laser-Doppler flowmetry, respectively. Peak FBF was obtained following 5 min forearm vascular occlusion and peak CBF in response to local skin heating of 42 degrees C. Blood pressure was measured manually and by Finapres. Maximal oxygen uptake (VO2max) was obtained from a treadmill exercise stress test. Age was associated with declines in resting FBF (y = -1.176 ln(x) + 6.6899, r(2) = 0.45) and peak FBF (y = -17.21 ln(x) + 93.843, r(2) = 0.53) (both p < 0.05). Peak CBF decreased with increasing age (y = -223.6 ln(x) + 1,102.9, r(2) = 0.34) (p < 0.05), but resting CBF was unchanged (p > 0.05). Males had higher resting and peak FBF than females (p < 0.05) and these variables were related to ageing better in males (y = -1.245 ln(x) + 7.188, r(2) = 0.71 and y = -18.53 ln(x) + 102.82, r(2) = 0.69) than in females (y = -1.149 ln(x) + 6.4307, r(2) = 0.38 and y = -16.59 ln(x) + 88.872, r(2) = 0.55). There were no sex differences in resting CBF (p > 0.05). Peak CBF was much better related to ageing in males than females (y = -276.1 ln(x) + 1,365.4, r(2) = 0.53 vs. y = -183.1 ln(x) + 907.86, r(2) = 0.28). VO2max decreased with advancing age and this decline was associated with the decline in peak FBF (y = -0.5933x + 10.91, r(2) = 0.36, p < 0.05) but not with peak CBF (p > 0.05). These results suggest that healthy ageing is associated with a curvilinear decline in resting and peak forearm and peak cutaneous vasodilator capacity, with males more severely affected than females. The data indicate that peak FBF is influenced by VO2max but peak CBF is not.

Impact of inactivity and exercise on the vasculature in humans.

The effects of inactivity and exercise training on established and novel cardiovascular risk factors are relatively modest and do not account for the impact of inactivity and exercise on vascular risk. We examine evidence that inactivity and exercise have direct effects on both vasculature function and structure in humans. Physical deconditioning is associated with enhanced vasoconstrictor tone and has profound and rapid effects on arterial remodelling in both large and smaller arteries. Evidence for an effect of deconditioning on vasodilator function is less consistent. Studies of the impact of exercise training suggest that both functional and structural remodelling adaptations occur and that the magnitude and time-course of these changes depends upon training duration and intensity and the vessel beds involved. Inactivity and exercise have direct "vascular deconditioning and conditioning" effects which likely modify cardiovascular risk.

Is the ratio of flow-mediated dilation and shear rate a statistically sound approach to normalization in cross-sectional studies on endothelial function?

It has been deemed important to normalize flow-mediated dilation (FMD), a marker of endothelial function, for between-subject differences in the eliciting shear rate (SR) stimulus. Conventionally, FMD is divided by the area under the curve of the SR stimulus. In the context of a cross-sectional comparison across different age cohorts, we examined whether this ratio approach adhered to established statistical assumptions necessary for reliable normalization. To quantify brachial artery FMD and area under the curve of SR, forearm cuff inflation to suprasystolic pressure was administered for 5 min to 16 boys aged 10.9 yr (SD 0.3), 48 young men aged 25.3 yr (SD 4.2), and 15 older men aged 57.5 yr (SD 4.3). Mean differences between age groups were statistically significant (P < 0.001) for nonnormalized FMD [children: 10.4% (SD 5.4), young adults: 7.5% (SD 2.9), older adults: 5.6% (SD 2.0)] but not for ratio-normalized FMD (P = 0.10). Moreover, all assumptions necessary for reliable use of ratio-normalization were violated, including regression slopes between SR and FMD that had y-intercepts greater than zero (P < 0.05), nonlinear and unstable relations between the normalized ratios and SR, skewed data distributions, and heteroscedastic variance. Logarithmic transformation of SR and FMD before ratio calculation improved adherence to these assumptions and resulted in age differences similar to the nonnormalized data (P = 0.03). In conclusion, although ratio normalization of FMD altered findings about age differences in endothelial function, this could be explained by violation of statistical assumptions. We recommend that exploration of these assumptions should be routine in future research. If the relationship between SR and FMD is generally found to be weak or nonlinear or variable between samples, then ratio normalization should not be applied.

Proteomic investigation of changes in human vastus lateralis muscle in response to interval-exercise training.

No previous study has used proteomics to investigate the effects of exercise training on human skeletal muscle. Five recreationally active men completed a 6-wk training programme involving three sessions per week, utilising six 1-min bouts at maximum oxygen uptake (V O(2)max) interspersed with 4 min at 50% V O(2)max. Vastus lateralis was biopsied at standardised times before and after the training intervention. Protein expression profiling was performed using differential analysis of 2-DE gels; complemented with quantitative analysis (iTRAQ) of tryptic peptides from 1-DE gel lane-segments using LC-MALDI MS/MS. Interval training increased average V O(2)max (7%; p<0.001) and was associated with greater expression of mitochondrial components, including succinate dehydrogenase, trifunctional protein-alpha and ATP synthase alpha- and beta-chains. 2-DE resolved 256 spots, and paired t-tests identified 20 significant differences in expression (false discovery rate <10%). Each differentially expressed gene product was present as multiple isoelectric species. Therefore, the differences in spot expression represent changes in post-transcriptional or post-translational processing. In particular, modulation of muscle creatine kinase and troponin T were prominent. Pro-Q Diamond staining revealed these changes in expression were associated with phosphorylated protein species, which provides novel information regarding muscle adaptation to interval training.

Brachial artery blood flow responses to different modalities of lower limb exercise.

INTRODUCTION/PURPOSE: Cycling is associated with a reproducible systolic anterograde and diastolic retrograde flow pattern in the brachial artery (BA) of the inactive upper limb, which results in endothelial nitric oxide (NO) release. The purpose of this study was to examine the impact of different types and intensities of lower limb exercise on the BA flow pattern. METHODS: We examined BA blood flow and shear rate patterns during cycling, leg kicking, and walking exercise in 12 young subjects (24 +/- 3 yr). BA diameter, blood flow, and shear rate were assessed at baseline (1 min) and at three incremental intensity levels of cycling (60, 80, and 120 W), bilateral leg kicking (5, 7.5, and 10 kg), and walking (3, 4, and 5 km x h(-1)), performed for 3 min each. Edge detection and wall tracking of high-resolution B-mode arterial ultrasound images, combined with synchronized Doppler waveform envelope analysis, were used to calculate conduit artery diameter and anterograde/retrograde blood flow and shear rate continuously across the cardiac cycle. RESULTS: BA mean blood flow and shear rate increased significantly throughout each exercise protocol (P < 0.001), and BA anterograde blood flow and shear rate showed comparable increases throughout each protocol (P < 0.001). Retrograde blood flow and shear rate, however, demonstrated a significant increase during cycling and walking (P < 0.001) but not during leg kicking. CONCLUSION: Rhythmic lower limb exercise (cycling and walking) results in an increase in BA systolic anterograde blood flow and shear rate, directly followed by a large retrograde flow and shear rate. This typical pattern, previously linked with endothelial NO release, is not present during a different type of exercise such as leg kicking.

Exercise training-induced gender-specific heat shock protein adaptations in human skeletal muscle.

This study investigates the effects of short-term endurance training on heat shock protein (HSP) adaptations of male and female human skeletal muscle. The data demonstrate that females did not respond to continuous or interval training in terms of increasing HSP content of the vastus lateralis muscle. In contrast, males displayed HSP adaptations to both training interventions. These data provide a platform for future human studies to examine a potential gender-specific stress response to exercise.

Trained men display increased basal heat shock protein content of skeletal muscle.

PURPOSE: 1) To compare the baseline levels of heat shock and antioxidant protein content in the skeletal muscle of trained and untrained humans and 2) to characterize the exercise-induced stress response of aerobically trained human skeletal muscle to an acute exercise challenge. METHODS: Resting muscle biopsies were obtained from the vastus lateralis muscle of six untrained and six aerobically trained young males. To characterize the stress response of a trained population, the trained subjects also performed a 45-min nondamaging running exercise protocol at an intensity corresponding to 75% of V O2max. Muscle biopsies were obtained from the vastus lateralis muscle at 48 h and 7 d after exercise. RESULTS: Trained subjects displayed significantly higher (P<0.05) resting levels of heat shock protein 60 (HSP60, 25%), alphaB-crystallin (43%), and manganese superoxide (MnSOD, 45%) protein content compared with untrained subjects. Trained subjects also exhibited no significant change (P > 0.05) in resting levels of HSP70 (16%), HSC70 (13%), and total superoxide dismutase (SOD) activity (46%) compared with untrained subjects. Resting HSP27 levels were unaffected by exercise training (P > 0.05). In the trained subjects, exercise failed to induce significant increases (P>0.05)in muscle content of HSP70, HSC70, HSP60, HSP27, alphaB-crystallin, and MnSOD protein content or in the activity of SOD at any time point after exercise. CONCLUSION: This study demonstrates for the first time that trained men display a selective up-regulation of basal heat shock and antioxidant protein content and do not exhibit a stress response to customary running exercise. It is suggested that an increase in these protective systems functions to maintain homeostasis during the stress of exercise by protecting against disruptions to the cytoskeleton/contractile machinery, by maintaining redox balance, and by facilitating mitochondrial biogenesis.

The impact of altered climatic conditions and altitude on circadian physiology.

Knowing the output of the "body clock" is fundamental to the science of chronobiology. As the clock resides within the suprachiasmatic nuclei, direct measurement is not feasible and therefore, characteristics of the clock are often inferred from the measurement of marker rhythms, one of which is core temperature. Core temperature is often the marker rhythm of choice due to ease of measurement, particularly in field conditions. However, if the output of the "body clock" is to be inferred from measurement of this variable, it is important to establish whether environmental conditions change or moderate the circadian rhythm of core temperature. Although the majority of circadian patterns do demonstrate independence from such exogenous influences, there does appear to be seasonal variation to their period. Given that humans can easily travel to environments of altered temperature and altitude, there is a need to ascertain the exact effect of such change on the rhythm of core temperature. This review will therefore outline the evidence that the circadian rhythm of core temperature is affected by ambient temperature and by hypoxia. Furthermore, the review will discuss whether these environmental factors act as zeitgebers (affecting the endogenous rhythm) or as masking influences of the inherent rhythm.

Time course and differential responses of the major heat shock protein families in human skeletal muscle following acute nondamaging treadmill exercise.

The exercise-induced expression of heat shock proteins (HSPs) in rodent models is relatively well defined. In contrast, comparable data from human studies are limited and the exercise-induced stress response of human skeletal muscle is far from understood. This study has characterized the time course and magnitude of the HSP response in the skeletal muscles of a healthy active, but untrained, young male population following a running exercise protocol. Eight subjects performed 45 min of treadmill running at a speed corresponding to their lactate threshold (11.7 +/- 0.5 km/h; 69.8 +/- 4.8% maximum O2 uptake). Muscle biopsies were obtained from the vastus lateralis muscle immediately before and at 24 h, 48 h, 72 h, and 7 days postexercise. Exercise induced a significant (P < 0.05) but variable increase in HSP70, heat shock cognate (HSC) 70, and HSP60 expression with peak increases (typically occurring at 48 h postexercise) to 210, 170, and 139% of preexercise levels, respectively. In contrast, exercise did not induce a significant increase in either HSP27, alphaB-crystallin, SOD 2 (MnSOD) protein content, or the activity of SOD and catalase. When examining baseline protein levels, HSC70, HSP27, and alphaB-crystallin appeared consistently expressed between subjects, whereas HSP70 and MnSOD displayed marked individual variation of up to 3- and 1.5-fold, respectively. These data are the first to define the time course and extent of HSP production in human skeletal muscle following a moderately demanding and nondamaging running exercise protocol. Data demonstrate a differential effect of aerobic exercise on specific HSPs.