Blood flow restriction accelerates aerobic training-induced adaptation of [Formula: see text] kinetics at the onset of moderate-intensity exercise.

It is unclear whether blood flow restriction (BFR) accelerates the adaptation of the time constant (τ) of phase II oxygen uptake ([Formula: see text]) kinetics in the moderate-intensity exercise domain via moderate-intensity aerobic training. Therefore, healthy participants underwent moderate-intensity [45-60% [Formula: see text] Reserve] aerobic cycle training with or without BFR (BFR group, n = 9; CON group, n = 9) for 8 weeks to evaluate [Formula: see text] kinetics during moderate-intensity cycle exercise before (Pre) and after 4 (Mid) and 8 (Post) weeks of training. Both groups trained for 30 min, 3 days weekly. BFR was performed for 5 min every 10 min by applying cuffs to the upper thighs. The τ significantly decreased by Mid in the BFR group (23.7 ± 2.9 s [Pre], 15.3 ± 1.8 s [Mid], 15.5 ± 1.4 s [Post], P < 0.01) and by Post in the CON group (27.5 ± 2.0 s [Pre], 22.1 ± 0.7 s [Mid], 18.5 ± 1.9 s [Post], P < 0.01). Notably, the BFR group's τ was significantly lower than that of the CON group at Mid (P < 0.01) but not at Post. In conclusion, BFR accelerates the adaptation of the [Formula: see text] kinetics of phase II by moderate-intensity aerobic training.

Effects of a 12-Month Pedometer-Based Walking Intervention in Women of Low Socioeconomic Status.

This study examined the effects of a 12-month walking intervention in overweight/obese, low socioeconomic women. Forty-six women (48.2 ± 8.0 years) entered the study. Outcomes included weight, waist and hip circumferences, body mass index (BMI), blood pressure, glycosylated hemoglobin, blood lipids, fibrinogen, and high-sensitivity C-reactive protein (hsCRP). Both intention-to-treat analyses in all participants and group analyses in study completers only (3K group = increased steps/day by ≥3,000; No Δ group = did not increase steps/day by ≥3,000) were conducted. Group × time ANOVA was used. In study completers, 3K significantly increased steps/day (6,903 ± 3,328 to 12,323 ± 5,736) compared to No Δ (4,926 ± 3,374 to 5,174 ± 3,095) from baseline to 12 months. There was a significant time effect for weight (P = 0.030), BMI (P = 0.029), and hsCRP (P = 0.044). Low socioeconomic women who adhere to a long-term, pedometer-based walking intervention significantly increased steps/day and may improve body weight, BMI, and hsCRP. This could help reduce health disparities in this population over time.

Using a practical approach for determining the most effective stretching strategy in female college division I volleyball players.

The purpose of this investigation was to quantify the effects that a practical bout of static stretching (SS) and dynamic stretching (DS) has on maximal countermovement jump (CMJ) height across a time spectrum of 25 minutes in National Collegiate Athletic Association Division I varsity volleyball players. Eleven female varsity volleyball players (mean ± SD; age 20.00 ± 1.55 years; height 1.78 ± 0.08 m; mass 74.55 ± 12.18 kg) volunteered for this investigation. Three days of randomized experimental testing (SS, DS, control) were completed. The SS protocol consisted of stretching 7 muscle groups. The DS protocol consisted of the volleyball team's actual DS routine of equal duration (30 seconds) to SS. Poststretch performance measures of CMJ were determined at 1, 5, 15, and 25 minutes poststretch. Countermovement jump had an acute significant trial-by-time interaction, indicating that DS was found to produce significantly higher scores than the SS and control session at 1 and 5 minutes poststretch, but not at 15 and 25 minutes poststretch. Additionally, there was a timing interaction within trials where SS scores were significantly lower at 1 minute poststretch compared with 5 and 25 minutes poststretch, and DS scores were significantly higher at 1 and 5 minutes poststretch compared with 15 and 25 minutes poststretch. Athletes engaging in competitive power sports should continue to utilize their DS routine but may need to do so within 5 minutes before activity.

The effects of ischemic preconditioning on aerobic and anaerobic variables associated with submaximal cycling performance.

Acute limb ischemia induced by pressure cuffs before activity (ischemic preconditioning; IPC) has been reported to improve exercise performance at maximal efforts. The purpose of this investigation was to determine the effects of IPC during a submaximal performance test in competitive amateur level cyclists. Twelve healthy, male cyclists participated in two performance tests in which they cycled at successive relative intensities of 30, 50, and 70% of their maximal power output for 5 min each. The test culminated with an intensity of 90% of their maximal power output until exhaustion. Prior to each test, subjects randomly completed a control (CON) or IPC treatment. The IPC treatment consisted of alternating 220 mmHg of pressure applied by a cuff to the proximal portion of both thighs for 3, 5 min bouts separated by 5 min of rest. In addition to performance time to exhaustion, variables associated with aerobic performance (oxygen consumption, ventilation, respiratory exchange ratio, heart rate, and blood lactate) were measured continuously throughout the performance test. Statistical comparisons of data were made with repeated measures analyses of variance or paired T tests and significance was accepted as P < 0.05. Heart rate at the 30% relative intensity was significantly higher for the IPC treatment, but there were no other statistically significant differences between the control and IPC treatments across all variables and relative intensities. In this group of competitive amateur-level cyclists, an acute treatment of IPC did not improve performance at each submaximal intensity or increase time to exhaustion.

Continuous and intermittent walking alters HDL(2)-C and LCATa.

PURPOSE: The purpose of this study was to determine if exercise, whether continuous (CE: completed all in one session) or intermittent (completed in either two (IE 2) or three (IE 3) exercise sessions) expending the same number of calories alters reverse cholesterol transport or low density lipoprotein (LDL) particle size. METHODS: Sixteen healthy (22±2.1 year old) men (VO(2) max=37.0±3.3mL/kg/min) randomly completed three exercise trials, CE, IE 2 and IE 3, expending 450 calories. Blood samples were drawn immediately post-exercise (IPE) and 24 and 48h following exercise and analyzed for total cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL-C), high density lipoprotein (HDL-C) and subfractions (HDL(2)-C, HDL(3)-C). Samples were also analyzed to determine LDL-C particle size, lecithin cholesterol acyl transferase activity (LCATa) and cholesterol ester transfer protein activity (CETPa). RESULTS: HDL(2)-C increased significantly 48h post-exercise in the CE and IE 2 groups. Additionally, the IE 3 group had significant increases in HDL(2)-C at 24 (39%) and 48h post-exercise by 66%. This change in HDL(2)-C was significantly and positively correlated (r=0.62; p<0.05) to the changes in LCATa which increased compared to baseline at 48h post-exercise in the CE and IE 3 groups. No significant changes in LDL particle size or alterations in CETPa were seen. CONCLUSIONS: The results of this study indicate that whether the exercise is continuous or intermittent, keeping calorie expenditure the same, causes significant changes in the HDL(2)-C subfraction, which was augmented by an increase in LCATa.

Postresistance exercise blood pressure reduction is influenced by exercise intensity in type-2 diabetic and nondiabetic individuals.

This study analyzed the postexercise blood pressure (BP) after resistance exercise (RE) on middle-aged type-2 diabetic (T2DM, n = 10, 46.6 +/- 13.1 years) and nondiabetic subjects (NDM, n = 10, 52.0 +/- 13.2 years). Participants performed (a) 1 repetition maximum (1RM) strength test; (b) 3 laps in an RE circuit of 6 exercises (16 repetitions at 43% 1RM); (c) 3 laps in an RE circuit (30 repetitions at 23% 1RM); and (d) a control session. The blood lactate concentration ([lac]) (YSI 2700S) and BP (Microlife BP3AC1-1) were measured pre-exercise, after exercise, and at each 15 minutes during the 120 minutes of recovery. Analysis of variance with Bonferroni as a post hoc evidenced that the 43% 1RM session elicited the highest [lac] response for both NDM (7.8 +/- 1.8 vs. 6.4 +/- 1.8 mmol x L(-1); p < 0.05) and T2DM (7.0 +/- 1.4 vs. 5.6 +/- 1.6 mmol x L(-1); p < 0.05). Also, the 43% 1RM session promoted a significant postexercise hypotension (PEH) of systolic blood pressure (SBP) and mean arterial pressure (MAP), whereas the 23% 1RM did not. The highest BP reductions for T2DM and NDM after 43% 1RM were, respectively, 9.5 +/- 11.1 and 11.0 +/- 7.1 mmHg for SBP and 6.4 +/- 7.8 and 7.7 +/- 7.9 mmHg for the MAP (p

Starch-entrapped biopolymer microspheres as a novel approach to vary blood glucose profiles.

BACKGROUND: With emerging knowledge of the impact of the metabolic quality of glycemic carbohydrates on human health, there is a need for novel carbohydrate ingredients that can be custom-made to deliver controlled amounts of glucose to the body and to test hypotheses on the postprandial metabolic consequences of carbohydrates. OBJECTIVE: The goal of the present study was to demonstrate the applicability and action of starch-entrapped biopolymer microspheres as customized, novel, slowly digestible carbohydrates to obtain desired glycemic responses. METHODS: Starch-entrapped microspheres were developed; and starch digestion and glucose release, subsequent to their cooking (100 degrees C, 20 min) in water, were initially monitored by measuring the rapidly digestible, slowly digestible, and resistant starch fractions using the in vitro Englyst assay. Glycemic and insulinemic responses after consumption of glucose and two different slowly digestible starch microsphere diets were compared using a crossover study in 10 healthy individuals. The mechanism of starch digestion in the microspheres was elucidated from scanning electron microscopic images of the in vitro digested microspheres. RESULTS: Factors such as biopolymer type and concentration, microsphere size, and starch type were manipulated to obtain starch materials with defined amounts of slowly digestible starch based on in vitro studies. Scanning electron microscopy showed that cooked starch entrapped in the dense biopolymer matrix is digested layer by layer from the outside to the inside of the microsphere. Glycemic and insulinemic responses to microsphere test diets were moderate as compared to a glucose diet, but more important, they showed extended glucose release. CONCLUSIONS: Starch-entrapped microspheres provide a useful tool to study the postprandial metabolic consequences of slowly digestible carbohydrates.

Comparison of early phase adaptations for traditional strength and endurance, and low velocity resistance training programs in college-aged women.

The purpose of this study was to investigate the effects of a six-week (16-17 training sessions) low velocity resistance training program (LV) on various performance measures as compared to a traditional strength (TS) and a traditional muscular endurance (TE) resistance training program. Thirty-four healthy adult females (21.1 +/- 2.7 y) were randomly divided into 4 groups: control (C), TS, TE, and LV. Workouts consisted of 3 exercises: leg press (LP), back squat (SQ), and knee extension (KE). Each subject was pre- and posttested for 1 repetition maximum (1RM), muscular endurance, maximal oxygen consumption (VO2max), muscular power, and body composition. After the pretesting, TS, TE, and LV groups attended a minimum of 16 out of 17 training sessions in which the LP, SQ, and KE were performed to fatigue for each of 3 sets. For each training session, TS trained at 6-10 RM and TE trained at 20-30 RM both with 1-2 second concentric/1-2 second eccentric; and LV trained at 6-10 RM, with 10 second concentric/4 s eccentric. Statistical significance was determined at an alpha level of 0.05. LV increased relative LP and KE 1 RM, but the percent increase was smaller than TS, and not different from C in the SQ. For muscular endurance, LV improved similarly to TE for LP and less than TS and TE for KE. Body composition improved for all groups including C (significant main effect). In conclusion, muscular strength improved with LV training however, TS showed a larger improvement. Muscular endurance improved with LV training, but not above what TE or TS demonstrated. For all other variables, there were no significant improvements for LV beyond what C demonstrated.

Pedometer measurement of physical activity and chronic disease risk factors of obese lower socioeconomic status African American women.

BACKGROUND: To evaluate physical activity with pedometers and health markers of chronic disease in obese, lower socioeconomic African American women. METHODS: Thirty-five women (48 +/- 8 years) wore pedometers for 2 weeks. One-way analyses of variances were used to compare age, weight, body mass indices (BMI), and health markers of chronic disease (including blood pressure, cholesterol, triglycerides, glycosylated hemoglobin, fibrinogen, C-reactive protein) between women who were classified by steps per day as sedentary (SED < 5000; 2941 +/- 1161 steps/d) or active (ACT > or = 5000; 7181 +/- 2398 steps/d). RESULTS: ACT had significantly lower BMI (ACT: 37.2 +/- 5.6; SED: 44.4 +/- 7.2 kg/m2) and hip circumferences (ACT: 37.2 +/- 5.6; SED: 44.4 +/- 37.2 cm) and higher total cholesterol (ACT: 230 +/- 53; SED: 191 +/- 32 mg/dL) than SED. There were no differences in health markers of chronic disease between SED and ACT. Pearson product moment correlations showed significant negative correlations between steps/d and weight (r = -.42), BMI (r = -.46), and hip circumference (r = -.47). CONCLUSIONS: Increased levels of physical activity were associated with reduced BMI and hip circumferences but were not associated with lower health markers for chronic disease in obese, lower socioeconomic African American women.

Iron status of young males and females performing weight-training exercise.

PURPOSE: To determine the effect of weight training on measures of iron status in young males and females. METHODS: Forty (27 female, 13 male) non-weight-trained college age subjects participated in a 12-wk weight-training program conducted 3 d.wk-1. Blood samples and food diaries were obtained pretraining and at 4-wk intervals. Blood was analyzed for hemoglobin, hematocrit, serum iron (SI), total iron binding capacity (TIBC), transferrin saturation (TS), serum ferritin (SF), soluble transferrin receptor (sTfR), and creatine kinase (CK). Subjects were grouped by SF level (FL, females < or = 20 microg.L-1; FN, females > 20 microg.L-1; ML, males < or = 45 microg.L-1; MN, males > or = 50 microg.L-1) to determine the impact of initial iron status on measured responses. RESULTS: Weight training increased strength and fat-free mass and decreased levels of percent body fat. Hemoglobin concentration declined after 12 wk of training (13.7 +/- 1.6 vs 13.2 +/- 1.7 g.dL-1), independent of gender or initial iron status. Only the MN group experienced a decline in SF level after 8 wk of training (129.7 +/- 77.9 vs 102.0 +/- 57.8 microg.L-1). No significant changes were observed for hematocrit, SI, TIBC, TS, sTfR, or CK measures. Total iron intake, but not heme or bioavailable iron intakes, declined at the 12th week of training compared with baseline (13.4 +/- 6.5 vs 10.7 +/- 4.8 mg.d-1) and was not significantly correlated with hematological or iron status measures. CONCLUSIONS: Hemoglobin concentration declines without alterations in SI, TIBC, TS, or sTfR after 12 wk of weight training. The SF level of males with adequate iron status is lowered with weight training but not among females or males with low iron status.

Blood glucose threshold and the metabolic responses to incremental exercise tests with and without prior lactic acidosis induction.

This study compared the metabolic-ventilatory responses and the glycemic threshold identified during lactate minimum (LM) and individual anaerobic threshold (IAT) tests. In addition, the ability to determine the anaerobic power, aerobic-anaerobic transition (Trans) (e.g. ventilatory threshold; VT) and the maximal oxygen consumption (VO(2max)) all within a single incremental treadmill test (IT) was investigated. Fifteen physically fit men [25.9 (5.5) years; 77.4 (6.5) kg] performed the following: test 1, IT for IAT; and test 2, LM: 30-s Wingate test followed by 8 min rest and then an IT that was the same as test 1. Blood lactate concentration [lac], glucose concentration [gluc], pH, PO(2), PCO(2), base excess (BE) and ventilatory variables were measured. At the beginning of the IT for LM, the ventilation, PO(2) and VO(2) were higher and the pH, BE and PCO(2) were lower in relation to IAT ( P<0.05), while no differences were observed after reaching LM intensity during IT. Moreover, the Trans could be identified by [lac] (IAT, LM), minute ventilation [V(E;) VT identified during IAT protocol (VT-IAT) and VT identified during LM protocol (VT-LM)], and [gluc] (IGT, GM) during the IT for IAT and LM. The velocities (kilometers per hour) corresponding to IAT (12.6+/-1.6), VT-IAT (12.5+/-1.7), IGT (12.6+/-1.6), LM (12.5+/-1.5), VT-LM (12.3+/-1.5), and GM (12.6+/-1.9) were not different from each other and the LM and IAT protocols resulted in the similar VO(2max). We concluded that: (1) after reaching the LM the metabolic responses during IT are similar to IAT; (2) performing a Wingate test prior to an IT does not interfere with the Trans and VO(2max) attainment; (3) and the IGT and GM can predict the Trans.