Validation of a generalized transfer function to noninvasively derive central blood pressure during exercise

Exercise brachial blood pressure ( BP) predicts mortality, but because of wave reflection, central ( ascending aortic) pressure differs from brachial pressure. Exercise central BP may be clinically important, and a noninvasive means to derive it would be useful. The purpose of this study was to test the validity of a noninvasive technique to derive exercise central BP. Ascending aortic pressure waveforms were recorded using a micromanometer-tipped 6F Millar catheter in 30 patients (56 +/- 9 years; 21 men) undergoing diagnostic coronary angiography. Simultaneous recordings of the derived central pressure waveform were acquired using servocontrolled radial tonometry at rest and during supine cycling. Pulse wave analysis of the direct and derived pressure signals was performed offline (SphygmoCor 7.01). From rest to exercise, mean arterial pressure and heart rate were increased by 20 +/- 10 mm Hg and 15 +/- 7 bpm, respectively, and central systolic BP ranged from 77 to 229 mm Hg. There was good agreement and high correlation between invasive and noninvasive techniques with a mean difference (+/- SD) for central systolic BP of -1.3 +/- 3.2 mm Hg at rest and -4.7 +/- 3.3 mm Hg at peak exercise ( for both r=0.995; P < 0.001). Conversely, systolic BP was significantly higher peripherally than centrally at rest (155 +/- 33 versus 138 +/- 32mm Hg; mean difference, -16.3 +/- 9.4mm Hg) and during exercise (180 +/- 34 versus 164 +/- 33 mm Hg; mean difference, -15.5 +/- 10.4 mm Hg; for both P < 0.001). True myocardial afterload is not reliably estimated by peripheral systolic BP. Radial tonometry and pulse wave analysis is an accurate technique for the noninvasive determination of central BP at rest and during exercise.

Does estrogen fluctuation throughout the menstrual cycle impact flow-mediated dilation during exercise in healthy premenopausal women?

The endothelium is the inner most layer of cells that lines all arteries. A primary function of endothelial cells is to regulate responses to increased blood flow and the resulting frictional forces or shear stress by producing factors such as nitric oxide that mediate arterial dilation (flow mediated dilation (FMD)). Menstrual cycle variations in estrogen (E2) have been shown to influence brachial artery (BA) FMD in response to transient increases in shear stress brought about by the release of a brief forearm occlusion (reactive hyperemia (RH)). FMD can also be assessed in response to a sustained shear stress stimulus such as that created with handgrip exercise (HGEX), and studies have shown that RH- and HGEX stimulated FMD provide unique information regarding endothelial function. However, the impact of menstrual phase on HGEX-FMD is unknown. Therefore, the purpose of this study was to determine the impact of cyclical changes in E2 levels on HGEX-FMD over two discrete phases of the menstrual cycle. FMD was assessed via ultrasound. 12 subjects (21 ± 2yrs) completed two experimental visits: (1) low estrogen phase (early follicular) and (2) High estrogen phase (late follicular). In each visit both RH- and HGEX-FMD (6 min handgrip exercise) were assessed. Results are mean ± SD. E2 increased from the low to the high estrogen phase of the menstrual cycle (low: 34 ± 8, high: 161 ± 113pg/mL, p = 0.004). There was no change in mean FMD between phases (RH-FMD: 7.7 ± 4.3% vs. 6.4 ± 3.1%, p = 0.139; HGEX-FMD: 4.8 ± 2.8% vs. 4.8 ± 2.3%, p = 0.979). The observation that both RH- and HGEX-FMD did not differ between phases indicates that menstrual cycle fluctuations in estrogen may not universally impact endothelial function in young, healthy premenopausal women. Further research is needed to improve our understanding of the mechanisms that underlie variability in the impact of menstrual phase on both transient and sustained FMD responses.

The effects of increased endurance training load on biomarkers of heat intolerance during intense exercise in the heat

The effects of increased training (IT) load on plasma concentrations of lipopolysaccharides (LPS), proinflammatory cytokines, and anti-LPS antibodies during exercise in the heat were investigated in 18 male runners, who performed 14 days of normal training (NT) or 14 days of 20% IT load in 2 equal groups. Before (trial 1) and after (trial 2) the training intervention, all subjects ran at 70% maximum oxygen uptake on a treadmill under hot (35 degrees C) and humid (similar to 40%) conditions, until core temperature reached 39.5 degrees C or volitional exhaustion. Venous blood samples were drawn before, after, and 1.5 h after exercise. Plasma LPS concentration after exercise increased by 71% (trial 1, p < 0.05) and 21% (trial 2) in the NT group and by 92% (trial 1, p < 0.01) and 199% (trial 2, p < 0.01) in the IT group. Postintervention plasma LPS concentration was 35% lower before exercise (p < 0.05) and 47% lower during recovery (p < 0.01) in the IT than in the NT group. Anti-LPS IgM concentration during recovery was 35% lower in the IT than in the NT group (p < 0.05). Plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha concentrations after exercise (IL-6, 3-7 times, p < 0.01, and TNF-alpha, 33%, p < 0.01) and during recovery (IL-6, 2-4 times, p < 0.05, and TNF-alpha, 30%, p < 0.01) were higher than at rest within each group. These data suggest that a short-term tolerable increase in training load may protect against developing endotoxemia during exercise in the heat.

Body temperature and its effect on leukocyte mobilization, cytokines and markers of neutrophil activation during and after exercise

We investigated the influence of rectal temperature on the immune system during and after exercise. Ten well-trained male cyclists completed exercise trials (90 min cycling at 60% VO(2max) + 16.1 - km time trial) on three separate occasions: once in 18 degrees C and twice in 32 degrees C. Twenty minutes after the trials in 32 degrees C, the cyclists sat for approximately 20 min in cold water (14 degrees C) on one occasion, whereas on another occasion they sat at room temperature. Rectal temperature increased significantly during cycling in both conditions, and was significantly higher after cycling in 32 degrees C than in 18 degrees C (P < 0.05). Leukocyte counts increased significantly during cycling but did not differ between the conditions. The concentrations of serum interleukin (IL)-6, IL-8 and IL-10, plasma catecholamines, granulocyte-colony stimulating factor, myeloperoxidase and calprotectin increased significantly following cycling in both conditions. The concentrations of serum IL-8 (25%), IL-10 (120%), IL-1 receptor antagonist (70%), tumour necrosis factor-alpha (17%), plasma myeloperoxidase (26%) and norepinephrine (130%) were significantly higher after cycling in 32 degrees C than in 18 degrees C. During recovery from exercise in 32 degrees C, rectal temperature was significantly lower in response to sitting in cold water than at room temperature. However, immune changes during 90 min of recovery did not differ significantly between sitting in cold water and at room temperature. The greater rise in rectal temperature during exercise in 32 degrees C increased the concentrations of serum IL-8, IL-10, IL-1ra, TNF-alpha and plasma myeloperoxidase, whereas the greater decline in rectal temperature during cold water immersion after exercise did not affect immune responses.

Effects of compression on lymphoedema during resistance exercise in women with breast cancer-related lymphoedema: A randomised, cross-over trial

Background The use of compression garments during exercise is recommended for women with breast cancer-related lymphoedema, but the evidence behind this clinical recommendation is unclear. The aim of this randomised, cross-over trial was to compare the acute effects of wearing versus not wearing compression during a single bout of moderate-load resistance exercise on lymphoedema status and its associated symptoms in women with breast cancer-related lymphoedema. Methods Twenty-five women with clinically diagnosed, stable unilateral breast cancer-related lymphoedema completed two resistance exercise sessions, one with compression and one without, in a randomised order separated by a 14 day wash-out period. The resistance exercise session consisted of six upper-body exercises, with each exercise performed for three sets at a moderate-load (10-12 repetition maximum). Primary outcome was lymphoedema, assessed using bioimpedance spectroscopy (L-Dex score). Secondary outcomes were lymphoedema as assessed by arm circumferences (percent inter-limb difference and sum-of-circumferences), and symptom severity for pain, heaviness and tightness, measured using visual analogue scales. Measurements were taken pre-, immediately post- and 24 hours post-exercise. Results There was no difference in lymphoedema status (i.e., L-Dex scores) pre- and post-exercise sessions or between the compression and non-compression condition [Mean (SD) for compression pre-, immediately post- and 24 hours post-exercise: 17.7 (21.5), 12.7 (16.2) and 14.1 (16.7), respectively; no compression: 15.3 (18.3), 15.3 (17.8), and 13.4 (16.1), respectively]. Circumference values and symptom severity were stable across time and treatment condition. Conclusions An acute bout of moderate-load, upper-body resistance exercise performed in the absence of compression does not exacerbate lymphoedema in women with breast cancer-related lymphoedema.

Compression use during an exercise intervention and associated changes in breast cancer-related lymphoedema

Aim This study assessed the association between compression use and changes in lymphoedema observed in women with breast cancer-related lymphoedema who completed a 12 week exercise intervention. Methods This work uses data collected from a 12 week exercise trial, whereby women were randomly allocated into either aerobic-based only (n=21) or resistance-based only (n=20) exercise. Compression use during the trial was at the participant’s discretion. Differences in lymphoedema (measured by L-Dex score and inter-limb circumference difference [%]) and associated symptoms between those who wore, and did not wear compression during the 12 week intervention were assessed. We also explored participants’ reasons surrounding compression during exercise. Results No significant interaction effect between time and compression use for lymphoedema was observed. There was no difference between groups over time in the number or severity of lymphoedema symptoms. Irrespective of compression use, there were trends for reductions in the proportion of women reporting severe symptoms, but lymphoedema status did not change. Individual reasons for the use of compression, or lack thereof, varied markedly. Conclusion Our findings demonstrated an absence of a positive or negative effect from compression use during exercise on lymphoedema. Current and previous findings suggest the clinical recommendation that garments must be worn during exercise is questionable, and its application requires an individualised approach.

Effect of caffeine ingestion during prolonged exhaustive exercise on salivary immunoglobulin A, alpha-amylase and cortisol

Exercise can have deleterious effects on the secretion of salivary immunoglobulin A (s-IgA), which appears to be related to perturbations in sympatheticoadrenal activation (Teeuw et al., 2004). Caffeine, commonly used for its ergogenic properties is associated with increased sympathetic nervous system activity, and it has been previously shown that caffeine ingestion before intensive cycling enhances s-IgA responses during exercise (Bishop et al., 2006). Therefore, the aim of the present study was to examine the effect of a performance cereal bar, containing caffeine, before and during prolonged exhaustive cycling on exercise performance and the salivary secretion of IgA, alpha-amylase activity and cortisol. Using a randomised cross-over design and following a 10 – 12 hour overnight fast, 12 trained cyclists, mean (SEM) age: 21(1) yr; height: 179(2) cm; body mass: 73.6(2.5) kg; maximal oxygen uptake, VO2max: 57.9(1.2) completed 2.5 h of cycling at 60%VO2max (with regular water ingestion) on a stationary ergometer, which was followed by a ride to exhaustion at 75% VO2max. Immediately before exercise, and after 55 min and 115 min of exercise participants ingested a 0.9 MJ cereal bar containing 45 g carbohydrate, 5 g protein, 3 g fat and 100 mg of caffeine (CAF) or an isocaloric noncaffeine bar (PLA). Unstimulated timed saliva samples were collected immediately before exercise, after 70 min and 130 min of exercise, and immediately after the exhaustive exercise bout. Saliva was analysed for s-IgA, alpha-amylase activity and cortisol concentration. Saliva flow rates were determined to calculate the s-IgA secretion rate. Data were analysed using a 2-way repeated measures ANOVA and post-hoc t-tests with Holm Bonferroni adjustments applied where appropriate. Time to exhaustion was 35% longer in CAF compared with PLA ((2177 (0.2) vs 1615 (0.16) s; P < 0.05)). Saliva flow rate did not change significantly during the exercise protocol. Exercise was associated with elevations in s-IgA concentration (9% increase), s-IgA secretion rate (24% increase) and alpha-amylase activity (224% increase) post-exhaustion (P < 0.01), but there was no effect of CAF on these responses. Salivary cortisol concentration increased by 64% post-exhaustion in the CAF trial only (P < 0.05), indicating an increase in adrenal activity following caffeine ingestion. Values were 35.7 (5.5) and 19.6 (3.4) nmol/L post-exhaustion for CAF and PLA, respectively. These findings show that ingestion of a caffeine containing cereal bar during prolonged exhaustive cycling enhances endurance performance, increases salivary cortisol secretion post-exhaustion, but does not affect the exercise-induced increases in s-IgA or alpha-amylase activity.

Dynamic magnetic resonance spectroscopy of phosphate energetics during muscle exercise and recovery

Entailing of phosphorus exchanges in most bio-chemicals as a key factor in disease, increases researcher’s interest to develop the technologies capable of detecting this metabolite. Phosphorus magnetic resonance spectroscopy is able to detect key metabolites in a non-invasive manner. Particularly, it offers the ability to measure the dynamic rate of phosphocreatine(PCr) degeneration through the exercise and recovery. This metric as a valid indication of mitochondrial oxidative metabolism in muscle, differentiate between normal and pathological state. To do magnetic resonance imaging and spectroscopy, clinical research tools provide a wide variety of anatomical and functional contrasts, however they are typically restricted to the tissues containing water or hydrogen atoms and they are still blind to the biochemicals of other atoms of interests. Through this project we intended to obtain the phosphorus spectrum in human body – specificadenerativelly in muscle – using 31P spectroscopy. To do so a double loop RF surface coil, tuned to phosphorus frequency, is designed and fabricated using bench work facilities and then validated through in vitro spectroscopy using 3 Tesla Siemens scanner. We acquired in vitro as well as in vivo phosphorus spectrum in a 100 mM potassium phosphate phantom and human calf muscle in rest-exercise-recovery phase in a 3T MR scanner. The spectrum demonstrates the main constituent in high-energy phosphate metabolism. We also observed the dynamic variation of PCr for five young healthy subjects who performed planter flexions using resistance band during exercise and recovery. The took steps in this project pave the way for future application of spectroscopic quantification of phosphate metabolism in patients affected by carotid artery disease as well as in age-matched control subjects.

Exercise domain profile through pulmonary gas exchange response during kendo practice by men

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of an isotonic beverage on autonomic regulation during and after exercise

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Manipulation effects of prior exercise intensity feedback by the Borg scale during open-loop cycling

Objective To verify the effects of exercise intensity deception by the Borg scale on the ratings of perceived exertion (RPE), heart rate (HR) and performance responses during a constant power output open-loop exercise. Methods Eight healthy men underwent a maximal incremental test on a cycle ergometer to identify the peak power output (PPO) and heart rate deflection point (HRDP). Subsequently, they performed a constant power output trial to exhaustion set at the HRDP intensity, in deception (DEC) and informed (INF) conditions: DEC-subjects were told that they would be cycling at an intensity corresponding to two categories below the RPE quantified at the HRDP; INF-subjects were told that they would cycle at the exact intensity corresponding to the RPE quantified at the HRDP. Results The PPO and power output at the HRDP obtained in maximal incremental tests were 247.5 +/- 32.1 W and 208.1 +/- 27.1 W, respectively. No significant difference in the time to exhaustion was found between DEC (525 +/- 244 s) or INF (499 +/- 224 s) trials. The slope and the first and second measurements of the RPE and HR parameters showed no significant difference between trials. Conclusions Psychophysiological variables such as RPE and HR as well as performance were not affected when exercise intensity was deceptively manipulated via RPE scores. This may suggest that unaltered RPE during exercise is a regulator of performance in this open-loop exercise.