Dehydroepiandrosterone in nails of infants: a potential biomarker of intrauterine responses to maternal stress

Easily accessible biomarkers for fetal stress biology are lacking. We here explore whether quantification of major fetal steroids, dehydroepiandrosterone (DHEA) or DHEA sulfate (DHEAS), with liquid chromatography/tandem mass spectrometry in infant nails is a tool to assess fetal stress biology in response to maternal stressful life events during pregnancy. Sufficient nail (≥1 mg) was available from 80 infants (93% of those providing samples). The concentration of DHEA, but not DHEAS, was increased in infants of mothers with stressful life events during pregnancy (DHEA: F_1,41 = 6.105, P = 0.018; DHEAS: F_1,77 = 0.767, P = 0.384). DHEA concentrations were not related to maternal stress before pregnancy (F_1,41 = 0.010, P = 0.922). Infant nail DHEA may be a fetal biological correlate of intrauterine exposure to maternal stress. The method promises the first non-invasive retrospective biomarker for intrauterine stress biology, opening new ways for research and clinical applications in fetal medicine, endocrinology, obstetrics, gynecology, and for understanding the developmental origins of health and disease.     

Effect of glutamine supplementation combined with resistance training in young adults

The purpose of this study was to assess the effect of oral glutamine supplementation combined with resistance training in young adults. A group of 31 subjects, aged 18–24 years, were randomly allocated to groups (double blind) to receive either glutamine (0.9 g·kg lean tissue mass^–1·day^–1; n=17) or a placebo (0.9 g maltodextrin·kg lean tissue mass^–1·day^–1; n=14) during 6 weeks of total body resistance training. Exercises were performed for four to five sets of 6–12 repetitions at intensities ranging from 60% to 90% 1 repetition maximum (1 RM). Before and after training, measurements were taken of 1 RM squat and bench press strength, peak knee extension torque (using an isokinetic dynamometer), lean tissue mass (dual energy X-ray absorptiometry) and muscle protein degradation (urinary 3-methylhistidine by high performance liquid chromatography). Repeated measures ANOVA showed that strength, torque, lean tissue mass and 3-methylhistidine increased with training (P<0.05), with no significant difference between groups. Both groups increased their 1 RM squat by approximately 30% and 1 RM bench press by approximately 14%. The glutamine group showed increases of 6% for knee extension torque, 2% for lean tissue mass and 41% for urinary levels of 3-methylhistidine. The placebo group increased knee extension torque by 5%, lean tissue mass by 1.7% and 3-methylhistidine by 56%. We conclude that glutamine supplementation during resistance training has no significant effect on muscle performance, body composition or muscle protein degradation in young healthy adults. Electronic Publication     

Correlation between plasma and saliva adrenocortical hormones in response to submaximal exercise

This study examined the relationships between plasma and saliva adrenocortical hormones in response to long-duration submaximal exercise. In nine healthy, physically active, female volunteers, blood and saliva samples were taken at rest and every 30 min during a 120-min cycling trial at 50–55% VO_2max for cortisol and dehydroepiandrosterone (DHEA) analysis. Correlation analysis revealed a moderate but significant relationship between plasma and saliva cortisol (r = 0.35, P < 0.02) and plasma and saliva DHEA (r = 0.47, P < 0.001) during the submaximal exercise. When expressed in percent of resting values, the correlations between the plasma and saliva concentrations were higher for both hormones during the exercise (cortisol: r = 0.72; DHEA: r = 0.68, P < 0.001). The results thus suggest that, even under prolonged exercise conditions, non-invasive saliva samples may offer a practical approach to assessing pituitary–adrenal function, especially when compared with individual basal values.     

Strength training effects on physical performance and serum hormones in young soccer players

To determine the effects of simultaneous explosive strength and soccer training in young men, 8 experimental (S) and 11 control (C) players, aged 17.2 (0.6) years, were tested before and after an 11-week training period with respect to the load-vertical jumping curve [loads of 0–70 kg (counter-movement jump CMJ0–70)], 5- and 15-m sprint performances, submaximal running endurance and basal serum concentrations of testosterone, free testosterone and cortisol. In the S group, the 11-week training resulted in significant increases in the low-force portion of the load-vertical jumping curve (5–14% in CMJ0–30, P<0.01) and in resting serum total testosterone concentrations (7.5%, P<0.05), whereas no changes were observed in sprint running performance, blood lactate during submaximal running, resting serum cortisol and resting serum free testosterone concentrations. In the C group, no changes were observed during the experimental period. In the S group, the changes in CMJ0 correlated (P<0.05–0.01) with the changes in the 5-m (r=0.86) and 15-m (r=0.92) sprints, whereas the changes in CMJ40 correlated negatively with the changes in the testosterone:cortisol ratio (r=–0.84, –0.92, respectively, P<0.05). These data indicate that young trained soccer players with low initial strength levels can increase explosive strength by adding low-frequency, low-intensity explosive-type strength training. The inverse correlations observed between changes in CMJ40 and changes in the testosterone:cortisol ratio suggest that a transient drop in this ratio below 45% cannot always be interpreted as a sign of overstrain or neuroendocrine dysfunction.An erratum to this article can be found at     

Effect of low-intensity resistance training on arterial function

Although high-intensity resistance training increases central arterial stiffness, moderate-intensity resistance training does not. However, the effects of low-intensity resistance training on arterial stiffness are unknown. The aim of this study was to investigate the effect of low-intensity resistance training with short inter-set rest period (LSR) on arterial stiffness. Twenty-six young healthy subjects were randomly assigned to training (10 males, 3 females) and control groups (9 males, 4 females). The subjects performed LSR twice a week at 50% of one repetition maximum for 10 weeks. Training consisted of five sets of ten repetitions with an inter-set rest period of 30 s. Changes in brachial-ankle pulse wave velocity (baPWV) and brachial flow-mediated dilation (FMD) were assessed before and after the intervention period. After the intervention period, one repetition maximum strength increased (by 9–38%, P < 0.05 to <0.001; increases varied among the exercise types), baPWV decreased (from 1,093 ± 148 to 1,020 ± 128 cm/s, P < 0.05), and brachial FMD increased (from 9.7 ± 1.3 to 11.8 ± 1.9%, P < 0.05). These values did not change in the control group. These results suggest that LSR reduced arterial stiffness and improved vascular endothelial function.     

Responses to eccentric and concentric resistance training in females and males

The adaptive responses to 12 weeks of accommodated resistance training were compared in females (n= 11) and males (n= 11). They performed four to five sets of six maximum bilateral coupled concentric and eccentric quadriceps muscle actions at 1.05 rad s^-1 three times per week. Uni- and bilateral concentric and eccentric peak torque at different angular velocities (0.52, 1.57 and 2.62 rad s^-1), three repetition maximum half-squat and vertical jump height were measured before and after training. Both groups displayed marked increases (P < 0.05) in concentric and eccentric peak torque at all angular velocities. The relative increases (P < 0.05) in unilateral concentric (26 vs. 26%) and eccentric (28 vs. 36%) peak torque across speeds were similar in females and males. The corresponding increases (P < 0.05) in bilateral concentric and eccentric peak torque across speeds were 20 vs. 28% and 24 vs. 39% respectively. The three repetition maximum half-squat (20 vs. 25%) and vertical jump height (10 vs. 8%) increased (P < 0.05) equally in females and males. These results suggest that the overall increases in concentric and eccentric peak torque and functional strength, in response to short-term accommodated resistance training, occur at a rate that is independent of sex. The torque-velocity relationship, however, appears to change in males suggesting a relatively greater enhancement of maximum voluntary force in the slow-speed, high-force region.     

Lipid and lipoprotein profiles, cardiovascular fitness, body composition, and diet during and after resistance, aerobic and combination training in young women

The purpose of this study was to evaluate the effects of various modes of training on the time-course of changes in lipoprotein-lipid profiles in the blood, cardiovascular fitness, and body composition after 16 weeks of training and 6 weeks of detraining in young women. A group of 48 sedentary but healthy women [mean age 20.4 (SD 1) years] were matched and randomly placed into a control group (CG, n=12), an aerobic training group (ATG, n=12), a resistance training group (RTG, n=12), or a cross-training group that combined both aerobic and resistance training (XTG, n=12). The ATG, RTG and XTG trained for 16 weeks and were monitored for changes in blood concentrations of lipoprotein-lipids, cardiovascular fitness, body composition, and dietary composition throughout a 16 week period of training and 6 weeks of detraining. The ATG significantly reduced blood concentrations of triglycerides (TRI) (P < 0.05) and significantly increased blood concentrations of high-density lipoprotein-cholesterol (HDL-C) after 16 weeks of training. The correlation between percentage fat and HDL-C was 0.63 (P < 0.05), which explained 40% of the variation in HDL-C, while the correlation between maximal oxygen uptake (V˙O_2max) and HDL-C was 0.48 (P < 0.05), which explained 23% of the variation in HDL-C. The ATG increased V˙O_2max by 25% (P < 0.001) and decreased percentage body fat by 13% (P < 0.05) after 16 weeks. Each of the alterations in the ATG had disappeared after the 6 week detraining period. The concentration of total cholesterol (TC), TRI, HDL-C and low density lipoprotein-cholesterol in the blood did not change during the study in RTG, XTG and CG. The RTG increased upper and lower body strength by 29% (P < 0.001) and 38%, respectively. The 6 week detraining strength values obtained in RTG were significantly greater than those obtained at baseline. The XTG increased upper and lower body strength by 19% (P < 0.01) and 25% (P < 0.001), respectively. The 6 week detraining strength values obtained in XTG were significantly greater than those obtained at baseline. The RTG, XTG and CG did not demonstrate any significant changes in either V˙O_2max, or body composition during the training and detraining periods. The results of this study suggest that aerobic-type exercise improves lipoprotein-lipid profiles, cardiorespiratory fitness and body composition in healthy, young women, while resistance training significantly improved upper and lower body strength only. Accepted: 9 April 2000     

Individual differences in the responses to endurance and resistance training

Large individual differences in the responsiveness of cardiorespiratory fitness (VO_2peak) to endurance training have been observed in healthy subjects. We tested the hypothesis that subjects with a poor responsiveness to endurance training might benefit from resistance training in terms of aerobic fitness. The study population consisted of sedentary healthy male and female subjects (n=91, 42±5 year) assigned to either a training (n=73) or a control group (n=18). The randomized cross-over study design included a 2-week laboratory-controlled endurance or resistance training period with a 2-month detraining period between the interventions. Large individual differences were observed in the changes of VO_2peak (ΔVO_2peak) after both the endurance (average 8±6 %, P<0.001, range −5 to +22%) and resistance training (average 4±5%, P<0.001, range −8 to +16%). The average increase in ΔVO_2peak between genders was similar after both the endurance (8±6% for both genders, P=ns) and resistance training (3±5% for males and 5±6% for females, P=ns). There was no linear relationship between the changes in VO_2peak after each training intervention (r=−.09, P=ns). On the contrary, when the study group was divided into quartiles according to the endurance training response (1±3, 6±1, 9±1, and 16±3% increase in VO_2peak), the group with the lowest response to endurance training increased VO_2peak after the resistance training intervention (ΔVO_2peak 7±5%, P<0.001). The individual responsiveness of VO_2peak to exercise training is related to the mode of training. The healthy males and females whose training response is low after endurance training seem to result in a marked improvement in their cardiorespiratory fitness by resistance training.     

Independent and combined effects of liquid carbohydrate/essential amino acid ingestion on hormonal and muscular adaptations following resistance training in untrained men

This investigation examined chronic alteration of the acute hormonal response associated with liquid carbohydrate (CHO) and/or essential amino acid (EAA) ingestion on hormonal and muscular adaptations following resistance training. Thirty-two untrained young men performed 12 weeks of resistance training twice a week, consuming ~675 ml of either, a 6% CHO solution, 6 g EAA mixture, combined CHO + EAA supplement or placebo (PLA). Blood samples were obtained pre- and post-exercise (week 0, 4, 8, and 12), for determination of glucose, insulin, and cortisol. 3-Methylhistidine excretion and muscle fibre cross-sectional area (fCSA) were determined pre- and post-training. Post-exercise cortisol increased (P<0.05) during each training phase for PLA. No change was displayed by EAA; CHO and CHO + EAA demonstrated post-exercise decreases (P<0.05). All groups displayed reduced pre-exercise cortisol at week 12 compared to week 0 (P<0.05). Post-exercise insulin concentrations showed no change for PLA; increases were observed for the treatment groups (P<0.05), which remained greater for CHO and CHO + EAA (P<0.001) than PLA. EAA and CHO ingestion attenuated 3-methylhistidine excretion 48 h following the exercise bout. CHO + EAA resulted in a 26% decrease (P<0.01), while PLA displayed a 52% increase (P<0.01). fCSA increased across groups for type I, IIa, and IIb fibres (P<0.05), with CHO + EAA displaying the greatest gains in fCSA relative to PLA (P<0.05). These data indicate that CHO + EAA ingestion enhances muscle anabolism following resistance training to a greater extent than either CHO or EAA consumed independently. The synergistic effect of CHO + EAA ingestion maximises the anabolic response presumably by attenuating the post-exercise rise in protein degradation.An erratum to this article can be found at     

Acute and cumulative effects of focused high-frequency vibrations on the endocrine system and muscle strength

The purpose of this study was to evaluate the acute and long-term effects of local high-intensity vibration (HLV, f = 300 Hz) on muscle performance and blood hormone concentrations in healthy young men. Totally 18 subjects (cV group) were studied in two sessions, either without (control) or with HLV treatment. The protocol was the same on both control and test days, except that, in the second session, subjects underwent HLV treatment. Counter-movement jumping (CMJ), maximal isometric voluntary contraction (MVC) test, and hormonal levels were measured before the procedure, immediately thereafter, and 1 h later. To assess the long-term effects of HLV, the cV group was subjected to HLV on the leg muscles for 4 weeks, and a second group (cR group, n = 18) embarked upon a resistance training program. All subjects underwent an MVC test and an isokinetic (100 deg/s) test before training, 4 weeks after training, and 2 months after the end of training. The HLV protocol significantly increased the serum level of growth hormone (GH, P < 0.05) and creatine phosphokinase (CPK, P < 0.05), and decreased the level of cortisol (P < 0.05). None of GH, CPK or testosterone levels were altered in controls. There was a significant improvement in MVC (P < 0.05). After 4 weeks, both the cV and cR groups demonstrated significant improvement in MVC and isokinetic tests (P < 0.05). This increase persisted for at least 2 months. Our results indicate that HLV influences the levels of particular hormones and improves neuromuscular performance. Our results indicate that HLV has a long-term beneficial effect comparable to that of resistance training.     

Effects of amount of training on the saliva concentrations of cortisol, dehydroepiandrosterone and on the dehydroepiandrosterone: cortisol concentration ratio in women over 16 weeks of training

This study was designed to investigate in the saliva the influence in female athletes of handball or volleyball training on concentrations of cortisol [C], dehydroepiandrosterone [DHEA], and on the [DHEA]:[C] ratio over 16 weeks of training. Data were compared to those of sedentary women. Saliva samples were collected upon waking after an overnight fast during the 1st week (W₁) of the training programme and in the 16th week (W₁₆). The training programme increased the resting concentrations of saliva [DHEA] in all the sportswomen. In contrast, a decrease of [DHEA] was noted in the sedentary group (W₁₆?1; P?1 and W₁₆, the [DHEA]:[C] ratio increased by more than 30% in all the sportswomen. In addition, the athletes with the highest performance levels and greatest amount of training had the lowest [DHEA]:[C] ratio. Negative linear relationships between the amount of training and the [DHEA]:[C] ratio were found both at W₁ (r?=??0.53 P?16 (r=?0.73 P?相似文献   

Increase in calf post-occlusive blood flow and strength following short-term resistance exercise training with blood flow restriction in young women

The response of calf muscle strength, resting (R _bf) and post-occlusive (PO_bf) blood flow were investigated following 4 weeks resistance training with and without blood flow restriction in a matched leg design. Sixteen untrained females performed unilateral plantar-flexion low-load resistance training (LLRT) at either 25% (n = 8) or 50% (n = 8) one-repetition maximum (1 RM). One limb was trained with unrestricted blood flow whilst in the other limb blood flow was restricted with the use of a pressure applied cuff above the knee (110 mmHg). Regardless of the training load, peak PO_bf, measured using venous occlusion plethysmography increased when LLRT was performed with blood flow restriction compared to no change following LLRT with unrestricted blood flow. A significant increase (P < 0.05) in the area under the blood time–flow curve was also observed following LLRT with blood flow restriction when compared LLRT with unrestricted blood flow. No changes were observed in R _bf between groups following training. Maximal dynamic strength (1 RM), maximal voluntary contraction and isokinetic strength at 0.52 and 1.05 rad s⁻¹ also increased (P < 0.05) by a greater extent following resistance training with blood flow restriction. Moreover, 1 RM increased to a greater extent following training at 50% 1 RM compared to 25% 1 RM. These results suggest that 4 weeks LLRT with blood flow restriction provides a greater stimulus to increase peak PO_bf as well as strength parameters than LLRT with unrestricted blood flow.     

Effects of dynamic resistance training on heart rate variability in healthy older women

Twenty healthy women aged between 65 and 74 years, trained three times a week, for 16 weeks, on a cycle ergometer, to determine the effects of dynamic resistance training on heart rate variability (HRV). Subjects were allocated to two training groups, high (HI, n=10) and low (LO, n=10) intensity. The HI group performed eight sets of 8 revolutions at 80% of the maximum resistance to complete 2 pedal revolutions (2RM); the LO group performed eight sets of 16 pedal revolutions at 40% of 2RM. Subjects were tested twice before, as control period (−4 weeks and 0 weeks) and once after training (16 weeks) for HRV, maximum voluntary contraction (MVC) of knee extensors and peak power (P _p) of lower limbs by jumping on a force platform. HRV was measured using time and frequency domain parameters. Two-way ANOVA for repeated measures was performed on all variables (P<0.05). Results showed no differences between training groups. Following training HRV was not modified, while MVC and P _p significantly increased. The two proposed forms of dynamic resistance training were appropriate to improve muscle power and strength in elderly females without affecting HRV. More research should verify the effects of an isometric and more prolonged training stimulus on HRV in older subjects. Electronic Publication     

Dehydroepiandrosterone and exercise in golden hamsters.

Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) are adrenal androgens that have been associated with a sense of well-being in humans. We describe two experiments done to test the hypothesis that an increase in DHEA or DHEAS secretion is associated with the inclination to exercise using a hamster model. In the first experiment, morning blood samples were obtained from adult male golden hamsters at various intervals after being placed in cages with (EX group) or without (SED group) access to running wheels. The EX group had lower DHEA (6, 12, and 14 weeks; p < 0.05) and DHEAS (13 and 16 weeks; p < 0.01) levels than the SED hamsters. In the second experiment, the number of wheel revolutions was monitored in castrated adult male hamsters implanted with Silastic capsules containing no hormone (blank control group), testosterone, or DHEA. The number of wheel revolutions in the group receiving DHEA was not significantly different than the blank control group, whereas testosterone increased wheel running at 4, 5, and 7 weeks (p < 0.05). These results indicate that DHEA and DHEAS levels decrease with exercise in male golden hamsters and that exogenous DHEA does not enhance the tendency to run on wheels.     

Effects of dehydroepiandrosterone supplement on health-related quality of life in glucocorticoid treated female patients with systemic lupus erythematosus

The objective of this study was to evaluate the efficacy of low dose dehydroepiandrosterone (DHEA) on health-related quality of life (HRQOL) in glucocorticoid treated female patients with systemic lupus erythematosus (SLE). Forty one women ( ≥ 5 mg prednisolone/day) were included in a double-blind, randomized, placebo-controlled study for 6 months where DHEA was given at 30 mg/20 mg ( ≤ 45/ ≥ 46 years) daily, or placebo, followed by 6 months open DHEA treatment to all patients. HRQOL was assessed at baseline, 6 and 12 months, using four validated questionnaires and the patients' partners completed a questionnaire assessing mood and behaviour at 6 months. DHEA treatment increased serum levels of sulphated DHEA from subnormal to normal. The DHEA group improved in SF-36 “role emotional” and HSCL-56 total score (both p < 0.05). During open DHEA treatment, the former placebo group improved in SF-36 “mental health” (p < 0.05) with a tendency for improvement in HSCL-56 total score (p = 0.10). Both groups improved in McCoy's Sex Scale during active treatment (p < 0.05). DHEA replacement decreased high-density lipoprotein (HDL) cholesterol and increased insulin-like growth factor I (IGF-I) and haematocrit. There were no effects on bone density or disease activity and no serious adverse events. Side effects were mild. We conclude that low dose DHEA treatment improves HRQOL with regard to mental well-being and sexuality and can be offered to women with SLE where mental distress and/or impaired sexuality constitutes a problem.     

The effects of resistance training on functional outcomes in patients with chronic obstructive pulmonary disease

Aerobic exercise training is used for rehabilitation in patients with chronic obstructive pulmonary disease (COPD), although it has little effect on muscle weakness and atrophy. Resistance training may be a useful addition to aerobic programs for these patients. The purpose of the present study was to investigate the effects of resistance training in addition to aerobic training on functional outcomes in patients with COPD. Seventeen COPD patients enrolled in an aerobic-based program that met twice a week were assigned to a 12-week control/aerobic [CON: n=8; 63 (8) years; mean (SD)] or a resistance/aerobic group [RES: n=9; 61 (7) years]. RES trained an additional twice a week on 12 resistance machines, performing three sets of 8–12 repetitions at 32–64% of their one-repetition maximum (1-RM) lifts. RES (P<0.05) increased upper (36%) and lower (36%) body strength, as well as lean body mass (5%), while CON showed little to no change. The 12-min walk distance increased (P<0.05) in only the RES [676 (219) to 875 (172) m]. Measurements of three of the eight tasks of activities of daily living improved in RES (P<0.05) compared to CON. This study demonstrated that progressive resistance training was well tolerated and improved functional outcomes in COPD patients that were currently involved in an aerobic training program.     

High-intensity endurance training improves adiponectin mRNA and plasma concentrations

Adiponectin is an anti-inflammatory protein that reduced in obesity. Exercise training may reduce the adipose tissue (AT), although it is not well known whether exercise-induced change in AT, increases the adiponectin mRNA expression and plasma concentrations or not; therefore, the purpose of this study was to investigate the adiponectin mRNA and plasma concentrations in middle-aged men after 12 weeks high-intensity exercise training and after a week detraining. Sixteen sedentary overweight and obese middle-aged men (age 41.18 ± 6.1 years; ± SD) volunteered to participate in this study. The subjects were randomly assigned to training group (n = 8) or control group (n = 8). The training group performed endurance training 4 days a week for 12 weeks at an intensity corresponding to 75–80% individual maximum oxygen consumption for 45 min. After 12 weeks of training, subjects underwent a week of detraining. The results showed that the BMI as well as central and peripheral AT volume were decreased in the training group compared to the control group (P < 0.05). After 12 weeks, the training group resulted in a significant increase (P < 0.05) in the adiponectin gene expression in abdominal and gluteal subcutaneous AT when compared with the control group. The results showed that plasma adiponectin concentrations increased and insulin resistance decreased after training compared to the control group (P < 0.05). After a week of detraining, the variables were not changed significantly in the training group. In conclusion, high-intensity endurance training caused an increase adiponectin mRNA in obese middle-aged men.     

Comparison of muscle buffer capacity and repeated-sprint ability of untrained, endurance-trained and team-sport athletes

We measured the muscle buffer capacity (βm) and repeated-sprint ability (RSA) of young females, who were either team-sport athletes (n=7), endurance trained (n=6) or untrained but physically active (n=8). All subjects performed a graded exercise test to determine followed 2 days later by a cycle test of RSA (5×6 s, every 30 s). Resting muscle samples (Vastus lateralis) were taken to determine βm. The team-sport group had a significantly higher βm than either the endurance-trained or the untrained groups (181±27 vs. 148±11 vs. 122±32 μmol H⁺ g dm⁻¹ pH⁻¹ respectively; P<0.05). The team-sport group also completed significantly more relative total work (299±27 vs. 263±31 vs. 223±21 J kg⁻¹, respectively; P<0.05) and absolute total work (18.2±1.6 vs. 14.6±2.4 vs. 13.0±1.9 kJ, respectively; P<0.05) than the endurance-trained or untrained groups during the RSA test. The team-sport group also had a greater post-exercise blood lactate concentration, but not blood pH. There was a significant correlation between βm and RSA (r = 0.67; P<0.05). Our findings show that young females competing in team sports have a larger βm than either endurance-trained or untrained females. This may be the result of the intermittent, high-intensity activity during training and the match play of team-sport athletes. The team-sport athletes also had a greater RSA than either the endurance-trained or untrained subjects. The greater total work by team-sport athletes was predominantly due to a better performance during the early sprints of the repeated-sprint bout.     

Effect of combined resistance and aerobic training on reactive hyperemia in men

Reduced response to reactive hyperemia (RH) in the extremities reflects impaired endothelium-dependent vasodilation of the microvasculature. The aims of the present study were to determine whether resistance training and a combination of aerobic and resistance training increase the endothelial vasodilation of the forearm assessed by RH. A total of 39 young men were assigned to either high-intensity resistance training (HIR; six types of exercises, 80% 1RM × 10 repetitions × 3 sets, n = 14) or moderate-intensity resistance training (MIR; six types of exercises, 50% 1RM × 16 repetitions × 3 sets, n = 14) or a combination of high-intensity resistance training and moderate-intensity endurance training (COMBO; HIR and 60% maximal heart rate × 30 min, n = 11) groups. We measured forearm blood flow response to RH before and after 4 months of exercise intervention. All training groups increased maximal strength in all muscle groups tested (all P < 0.05). After 4 months of training, the forearm blood flow during RH increased significantly in the MIR and COMBO groups, from 57 ± 4 to 66 ± 7 ml/min per 100 ml tissue and from 59 ± 6 to 74 ± 8 ml/min per 100 ml tissue, respectively (both P < 0.05). There was no change in the response to RH in the HIR groups. In conclusion, the findings in this study demonstrate that combined resistance and aerobic training may affect the vasoreactivity response to RH in the forearm, but not resistance training alone.