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Appl Physiol Nutr Metab [journal]
- Book review. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):587.
- Effects of an acute bout of resistance exercise on fiber-type specific to GLUT4 and IGF-1R expression. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):581-6.
The effects of resistance exercise on fiber-type-specific expression of insulin-like growth factor I receptor (IGF-1R) and glucose transporter 4 (GLUT4) was determined in 6 healthy males. The expression of both genes increased in Type I fibers (p < 0.05), but only GLUT4 increased (p < 0.05) in Type II fibers. These data demonstrates that an acute bout of resistance exercise can up-regulate mechanisms of glucose uptake in slow and fast-twitch fibers, but the IGF signaling axis may not be as effective in fast-twitch fibers.
- Open-ended time durations for stationary start intense cycle ergometer exercise testing. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):574-80.
The study involved application of different applied loads to measure altered test durations, time to peak power, peak power, and peak cadence during intense cycle ergometry exercise. Healthy, physically active male (n = 11) and female (n = 11) subjects (18-45 years) performed the following 3 bouts of intense cycle ergometry at peak cadence to volitional exhaustion on 3 separate days, 48 h to 1 week apart: (i) 85 g·kg(-1) body mass load; (ii) 75 g·kg(-1) body mass load; and (iii) 100 g·kg(-1) body mass load. Trials (ii) and (iii) were performed in random order after trial (i). Exercise consisted of a stationary start, where test termination occurred when cadence decreased to <35 r·min(-1). Mean (±SD) for gender main effects for time to peak power were 7.64 ± 2.76 vs. 9.49 ± 2.76 s (p < 0.001) for males and females, respectively. Relative peak power data for males vs. females for 75, 85, and 100 g·kg(-1) were 10.01 ± 1.371 vs. 7.81 ± 1.25, 10.16 ± 1.61 vs. 7.67 ± 1.35, and 10.91 ± 2.03 vs. 7.31 ± 1.37 W·kg(-1), respectively. The means for test duration for the GENDER × LOAD interaction (p = 0.09) were 68.25 ± 17.80 vs. 56.5 ± 11.56, 63.70 ± 17.21 vs.57.95 ± 10.45, and 51.99 ± 14.59 vs. 49.54 ± 12.45 s for males vs. females for each of 75, 85, and 100 g·kg(-1), respectively. Stepwise multiple regression involving load and gender resulted in an explanation of variance (R(2)) of only 31.2%. Open-ended testing should be performed at a load of 100 g·kg(-1) body mass for males and 85 g·kg(-1) body mass females, causing volitional exhaustion in approximately 60 s and should allow test duration to be another measured variable.
- Prolonged moderate-intensity exercise oxygen uptake response following heavy-intensity priming exercise with short- and longer-term recovery. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):566-73.
This study examines the effects of recovery duration following heavy-intensity "priming" exercise (Hvy) on pulmonary oxygen (O2) uptake (V̇O2p) during subsequent prolonged moderate-intensity exercise (Mod). Nine participants (6 men and 3 women) (27 ± 7 years) each completed 3 repetitions of 2 continuous Mod 1-Hvy-Mod 2 leg-cycling protocols in which Mod 2 lasted 30 min, but was preceded by a recovery duration of either 6 (R6) or 20 (R20) min at 20 W following Hvy; in each case, Mod 1 and Hvy lasted 6 min and were preceded by 6 min at 20 W. V̇O2p, heart rate (HR), and near-infrared spectroscopy (NIRS)-derived muscle deoxygenation ([HHb]) responses were modeled as a monoexponential; additionally, 60-s averages were computed every 6 min in Mod 1 and Mod 2. V̇O2p was elevated (p < 0.05) throughout Mod 2 compared with Mod 1 in both R6 and R20 (by -82 mL·min(-1) or ∼5.0%); this occurred despite a complete recovery of baseline V̇O2p (V̇O2pBsln) following R20. HR and minute ventilation (V̇E), but not [HHb], were also elevated throughout Mod 2. The phase II time constant for V̇O2p (τV̇O2p) was reduced in Mod 2 (22 s (Mod 1), 19 s (Mod 2); p < 0.05), as was the "overshoot" in the normalized [HHb]/O2 uptake ratio (p < 0.05). This study shows that V̇O2p was elevated during Mod following Hvy, regardless of recovery duration; however, a determining role for V̇O2pBsln is precluded. Furthermore, neither V̇O2p, HR, nor V̇E showed any evidence of a readjustment back to no-Hvy conditions during prolonged Mod (p > 0.05). Lastly, regardless of recovery duration, τV̇O2p was reduced to a similar extent with Hvy, likely resulting from an improved matching of local muscle O2 delivery to O2 utilization.
- Antioxidant effect of organic purple grape juice on exhaustive exercise. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):558-65.
This study aimed to assess the potential protective effect of organic purple grape juice (PGJ) on oxidative stress produced by an exhaustive exercise bout in rats. To test this hypothesis, rats were acutely treated with organic PGJ (Vitis labrusca) and subsequently submitted to an exhaustive exercise bout. Parameters of oxidative stress, such as thiobarbituric acid reactive species (TBARS) levels, 2',7',-dichlorofluorescein diacetate (DCFH-DA) oxidation, and nonprotein sulfhydryl levels (NP-SH) in the brain, skeletal muscle, and blood, were evaluated. Enzyme activity of Na(+),K(+)-ATPase, Ca(2+)-ATPase, and δ-aminolevulinate dehydratase (δ-ALA-D) in the brain, skeletal muscle, and blood were also assayed. Statistical analysis showed that the exhaustive exercise bout increased TBARS levels and DCFH-DA oxidation, and decreased NP-SH levels in rat tissue. Ca(2+)-ATPase activity was increased in groups exposed to both exercise and PGJ treatment. The results indicate that organic PGJ intake was able to protect against the oxidative damage caused by an exhaustive exercise bout in different rat tissues.
- Effect of plasma donation and blood donation on aerobic and anaerobic responses in exhaustive, severe-intensity exercise. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):551-7.
The purpose of this study was to investigate the immediate and delayed effects of plasma donation and blood donation on responses in exhaustive, severe-intensity exercise. Nineteen young men and women performed exhaustive cycle ergometer tests at ∼3.3 W·kg(-1) before and then 2 h, 2 days, and 7 days after withdrawal of either 8-10 mL·kg(-1) (∼700 mL) of plasma (n = 10) or 1 unit (450 mL) of whole blood (n = 9). Time to exhaustion was significantly (p < 0.05) decreased after the removal of plasma (-11% after 2 h) and after the removal of blood (-19% after 2 h and -7% after 2 days). Maximal oxygen uptake ([Formula: see text]) was not affected by plasma donation, but [Formula: see text] was reduced following blood withdrawal (-15% after 2 h, -10% after 2 days, and -7% after 7 days) presumably because of effects on blood volume, total haemoglobin content, and haemoglobin concentration. The kinetics of the oygen uptake ([Formula: see text]) response was not affected by either intervention. Two measures of anaerobic capacity, postexercise blood lactate concentration, and maximal accumulated oxygen deficit were reduced (-14%, -15%, respectively) 2 h after plasma donation, but neither was affected by blood donation. Removal of plasma and removal of blood have different effects on blood constituency, on the [Formula: see text] response, and on performance. Plasma donation appears to affect exercise performance because of reduced anaerobic capacity, whereas blood donation affects performance because of lowered [Formula: see text].
- Effect of exercise training on diastolic function in metabolic syndrome. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):545-50.
It has been reported that metabolic syndrome (MetS) impairs left ventricular (LV) diastolic function. The objective of this study was to determine whether exercise training can improve LV diastolic function in individuals with MetS. Twenty-eight individuals with MetS (9 males, aged 60 ± 5 years) underwent a 1-year combined endurance and resistance exercise training program; maximal aerobic capacity (V̇O2max), blood pressure, blood markers, and LV diastolic function were measured at weeks 0, 12, 24, and 52 throughout the training. Pulsed wave Doppler echocardiography across the mitral valve was used to assess peak early flow velocity (E) and peak atrial flow velocity (A) to determine the E/A ratio. Individuals with MetS had a reversed E/A ratio, suggesting impaired LV relaxation, the first stage of LV diastolic dysfunction. Exercise training reduced systolic blood pressure (SBP) (129 ± 14 to 120 ± 12 mm Hg; p < 0.01) and increased V̇O2max (29.2 ± 6.3 to 33.4 ± 6.5 mL·kg(-1)·min(-1); p < 0.01) and high-density lipoprotein cholesterol (1.04 ± 0.21 to 1.12 ± 0.25 mmol·L(-1); p = 0.02), but did not improve LV diastolic function. Individuals with an E/A ratio <1 at the start of training had a tendency toward an increased E/A ratio (p = 0.12) accompanied by significant decreases in SBP and increases in V̇O2max with exercise training. Combined resistance and aerobic exercise training improved cardiometabolic health but did not improve the impaired LV diastolic function of individuals with MetS.
- Comparison of intra-arterial and manual auscultation of blood pressure during submaximal exercise in humans. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):537-44.
Blood pressure (BP) is a key measure of cardiovascular function, and accurate measurement is important to ensure proper clinical evaluation, diagnosis, and treatment. We compared intra-arterial (direct) and cuff auscultation (manual) measurement techniques at rest and during 2 levels of submaximal constant-load exercise (9 min at 40% and 75% maximum watts). Sixty-four adults (aged 29.0 ± 0.7 years; 48% male; height, 173.7 ± 1.2 cm; mass, 73.0 ± 1.7 kg; body mass index, 24.1 ± 0.4 kg·m(-2); body surface area, 1.87 ± 0.03 m(2)) participated in the study. At rest, low, and moderate intensity, direct measurement demonstrated higher systolic BP (SBP) and diastolic BP (DBP) (bias for SBP: 22, 31, and 27 mm Hg and for DBP: 5, 7, and 17 mm Hg; rest, low-, and moderate-intensity, respectively; p < 0.01). At rest, the correlation and agreement between the 2 methods was modest (SBP: r = 0.56, bias = +22.1 mm Hg; DBP: r = 0.53, bias = +4.9 mm Hg; p < 0.001). There was good correlation and agreement with SBP at low and moderate intensity; however, DBP demonstrated a weaker relationship (SBP: r = 0.74 and 0.74, bias = +30.2 and +26.8 mm Hg; DBP: r = 0.39 and 0.28, bias = +7.1 and +13.4 mm Hg; for low and moderate intensity, respectively; p < 0.001). Further, manual measurement demonstrated a greater slope from rest to moderate exercise for the relationship between pulse pressure (PP) and cardiac output (13.6 ± 0.4 vs 12.3 ± 0.4, p = 0.03). As exercise intensity increases, manual DBP tends to bias low compared with direct DBP, which, when combined with parallel increases in SBP, leads to no differences in PP between methods at moderate exercise. Because PP is used to calculate other cardiovascular parameters (mean arterial pressure, systemic vascular resistance), measurement technique and exercise intensity should be considered when using cardiovascular variables as outcome measures.
- A study of DNA protective effect of orange juice supplementation. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):533-6.
The potential acute genoprotective effect of orange juice supplementation was investigated. Six healthy subjects (aged 33 to 60 years; 3 women and 3 men) were asked to drink 400 mL of commercial orange juice, which contained 100 mg vitamin C and 40.8 g sugar. Venous blood (2 mL) was taken before and 2 h after ingestion (test trial). A week later, the subjects were asked to repeat the trial by drinking 400 mL water with 100 mg vitamin C and 40.8 g glucose (control trial). Lymphocytes isolated from blood samples underwent comet assay on the day of collection. Pre- and postingestion DNA damage scores were measured in both the test and control trials. Results showed that there was a significant decrease in DNA damage induced by hydrogen peroxide after 2 h of supplementation with orange juice, and no change in baseline DNA damage. There was no significant decrease in the DNA damage in lymphocytes in the control trial.
- The ergogenic effect of beta-alanine combined with sodium bicarbonate on high-intensity swimming performance. [Journal Article]
- Appl Physiol Nutr Metab 2013 May; 38(5):525-32.
We investigated the effect of beta-alanine (BA) alone (study A) and in combination with sodium bicarbonate (SB) (study B) on 100- and 200-m swimming performance. In study A, 16 swimmers were assigned to receive either BA (3.2 g·day(-1) for 1 week and 6.4 g·day(-1) for 4 weeks) or placebo (PL; dextrose). At baseline and after 5 weeks of supplementation, 100- and 200-m races were completed. In study B, 14 were assigned to receive either BA (3.2 g·day(-1) for 1 week and 6.4 g·day(-1) for 3 weeks) or PL. Time trials were performed once before and twice after supplementation (with PL and SB), in a crossover fashion, providing 4 conditions: PL-PL, PL-SB, BA-PL, and BA-SB. In study A, BA supplementation improved 100- and 200-m time-trial performance by 2.1% (p = 0.029) and 2.0% (p = 0.0008), respectively. In study B, 200-m time-trial performance improved in all conditions, compared with presupplementation, except the PL-PL condition (PL-SB, +2.3%; BA-PL, +1.5%; BA-SB, +2.13% (p < 0.05)). BA-SB was not different from BA-PL (p = 0.21), but the probability of a positive effect was 78.5%. In the 100-m time-trial, only a within-group effect for SB was observed in the PL-SB (p = 0.022) and BA-SB (p = 0.051) conditions. However, 6 of 7 athletes swam faster after BA supplementation. The probability of BA having a positive effect was 65.2%; when SB was added to BA, the probability was 71.8%. BA and SB supplementation improved 100- and 200-m swimming performance. The coingestion of BA and SB induced a further nonsignificant improvement in performance.