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Showing papers in "European Journal of Applied Physiology in 2015"


Journal ArticleDOI
TL;DR: BFRT protocols benefit from higher occlusion pressure (80 %) when exercising at very low intensities when considering muscle strength, and conventional high-intensity resistance training (RT) protocols seem less effective than high- intensity RT.
Abstract: We compared the effects of different protocols of blood-flow restriction training (BFRT) with different occlusion pressures and/or exercise intensities on muscle mass and strength We also compared BFRT protocols with conventional high-intensity resistance training (RT) Twenty-six subjects had each leg allocated to two of five protocols BFRT protocols were performed at either 20 or 40 % 1-RM with either 40 or 80 % occlusion pressure: BFRT20/40, BFRT20/80, BFRT40/40, and BFRT40/80 Conventional RT was performed at 80 % 1-RM (RT80) without blood-flow restriction Maximum dynamic strength (1-RM) and quadriceps cross-sectional area (CSA) were assessed at baseline and after 12 weeks Regarding muscle mass, increasing occlusion pressure was effective only at very low intensity (BFRT20/40 078 % vs BFRT20/80 322 %) No additional increase was observed at higher intensities (BFRT40/40 445 % vs BFRT40/80 530 %), with no difference between the latter protocols and RT80 (590 %) Exercise intensity played a role in CSA when comparing groups with similar occlusion pressure Muscle strength was similarly increased among BFRT groups (~1210 %) but to a lesser extent than RT80 (2160 %) In conclusion, BFRT protocols benefit from higher occlusion pressure (80 %) when exercising at very low intensities Conversely, occlusion pressure seems secondary to exercise intensity in more intense (40 % 1-RM) BFRT protocols Finally, when considering muscle strength, BFRT protocols seem less effective than high-intensity RT

137 citations


Journal ArticleDOI
TL;DR: The findings indicate that arm circumference and SBP should be taken into account when determining BFR cuff pressures and confirmed that thigh circumference is the greatest predictor of arterial occlusion in the lower body.
Abstract: To determine what factors should be accounted for when setting the blood flow restriction (BFR) cuff pressure for the upper and lower body. One hundred and seventy one participants visited the laboratory for one testing session. Arm circumference, muscle (MTH) and fat (FTH) thickness were measured on the upper arm. Next, brachial systolic (SBP) and diastolic (DBP) blood pressure measurements were taken in the supine position. Upper body arterial occlusion was then determined using a Doppler probe. Following this, thigh circumference and lower body arterial occlusion were determined. Models of hierarchical linear regression were used to determine the greatest predictor of arterial occlusion in the upper and lower body. Two models were employed in the upper body, a Field (arm size) and a Laboratory model (arm composition). The Laboratory model explained 58 % of the variance in arterial occlusion with SBP (β = 0.512, part = 0.255), MTH (β = 0.363, part = 0.233), and FTH (β = 0.248, part = 0.213) contributing similarly to explained variance. The Field model explained 60 % of the variance in arterial occlusion with arm circumference explaining the greatest amount (β = 0.419, part = 0.314) compared to SBP (β = 0.394, part = 0.266) and DBP (β = 0.147, part = 0.125). For the lower body model the third block explained 49 % of the variance in arterial occlusion with thigh circumference (β = 0.579, part = 0.570) and SBP (β = 0.281, part = 0.231) being significant predictors. Our findings indicate that arm circumference and SBP should be taken into account when determining BFR cuff pressures. In addition, we confirmed our previous study that thigh circumference is the greatest predictor of arterial occlusion in the lower body.

124 citations


Journal ArticleDOI
TL;DR: These findings suggest that dietary NO3− enhances repeated sprint performance and may attenuate the decline in cognitive function (and specifically reaction time) that may occur during prolonged intermittent exercise.
Abstract: It is possible that dietary nitrate (NO 3 − ) sup- plementation may improve both physical and cognitive performance via its influence on blood flow and cellular energetics.

120 citations


Journal ArticleDOI
TL;DR: Oral curcumin likely reduces pain associated with DOMS with some evidence for enhanced recovery of muscle performance and mechanisms and translational effects on sport or vocational performance are required.
Abstract: Oral curcumin decreases inflammatory cytokines and increases muscle regeneration in mice. To determine effects of curcumin on muscle damage, inflammation and delayed onset muscle soreness (DOMS) in humans. Seventeen men completed a double-blind randomized-controlled crossover trial to estimate the effects of oral curcumin supplementation (2.5 g twice daily) versus placebo on single-leg jump performance and DOMS following unaccustomed heavy eccentric exercise. Curcumin or placebo was taken 2 d before to 3 d after eccentric single-leg press exercise, separated by 14-d washout. Measurements were made at baseline, and 0, 24 and 48-h post-exercise comprising: (a) limb pain (1–10 cm visual analogue scale; VAS), (b) muscle swelling, (c) single-leg jump height, and (d) serum markers of muscle damage and inflammation. Standardized magnitude-based inference was used to define outcomes. At 24 and 48-h post-exercise, curcumin caused moderate-large reductions in pain during single-leg squat (VAS scale −1.4 to −1.7; 90 %CL: ±1.0), gluteal stretch (−1.0 to −1.9; ±0.9), squat jump (−1.5 to −1.1; ± 1.2) and small reductions in creatine kinase activity (−22–29 %; ±21–22 %). Associated with the pain reduction was a small increase in single-leg jump performance (15 %; 90 %CL ± 12 %). Curcumin increased interleukin-6 concentrations at 0-h (31 %; ±29 %) and 48-h (32 %; ±29 %) relative to baseline, but decreased IL-6 at 24-h relative to post-exercise (−20 %; ±18 %). Oral curcumin likely reduces pain associated with DOMS with some evidence for enhanced recovery of muscle performance. Further study is required on mechanisms and translational effects on sport or vocational performance.

108 citations


Journal ArticleDOI
TL;DR: Investigating electromyographic amplitude, EMG mean power frequency, exercise volume, total work, iEMG, and TUCL during, and muscle cross-sectional area before and after 3 sets to failure of leg extension exercise found muscle activation was greater at 80 % 1RM.
Abstract: Purpose The purpose of this study was to investigate electromyographic amplitude (EMG AMP), EMG mean power frequency (MPF), exercise volume (VOL), total work and muscle activation (iEMG), and time under concentric load (TUCL) during, and muscle cross-sectional area (mCSA) before and after 3 sets to failure at 80 vs. 30 % 1RM resistance exercise.

106 citations


Journal ArticleDOI
TL;DR: The above approach can yield useful information on the bioenergetics and biomechanics of accelerated/decelerated running on flat terrain and, on a 10 % down-sloping track Bolt could cover 100 m in 8.2 s.
Abstract: To estimate the energetics and biomechanics of accelerated/decelerated running on flat terrain based on its biomechanical similarity to constant speed running up/down an ‘equivalent slope’ dictated by the forward acceleration (a f). Time course of a f allows one to estimate: (1) energy cost of sprint running (C sr), from the known energy cost of uphill/downhill running, and (2) instantaneous (specific) mechanical accelerating power (P sp = a f × speed). In medium-level sprinters (MLS), C sr and metabolic power requirement (P met = C sr × speed) at the onset of a 100-m dash attain ≈50 J kg−1 m−1, as compared to ≈4 for running at constant speed, and ≈90 W kg−1. For Bolt’s current 100-m world record (9.58 s) the corresponding values attain ≈105 J kg−1 m−1 and ≈200 W kg−1. This approach, as applied by Osgnach et al. (Med Sci Sports Exerc 42:170–178, 2010) to data obtained by video-analysis during soccer games, has been implemented in portable GPS devices (GPEXE©), thus yielding P met throughout the match. Actual O2 consumed, estimated from P met assuming a monoexponential VO2 response (Patent Pending, TV2014A000074), was close to that determined by portable metabolic carts. Peak P sp (W kg−1) was 17.5 and 19.6 for MLS and elite soccer players, and 30 for Bolt. The ratio of horizontal to overall ground reaction force (per kg body mass) was ≈20 % larger, and its angle of application in respect to the horizontal ≈10° smaller, for Bolt, as compared to MLS. Finally, we estimated that, on a 10 % down-sloping track Bolt could cover 100 m in 8.2 s. The above approach can yield useful information on the bioenergetics and biomechanics of accelerated/decelerated running.

99 citations


Journal ArticleDOI
TL;DR: It appears that both chronotype and habitual training time-of-day need to be considered when assessing diurnal variation in performance, as both types had lower fatigue and higher vigour prior to the 18h30 TT.
Abstract: Purpose The aim of this study was to compare morning and evening time-trial performance, RPE and mood state of trained swimmers, taking into account chronotype, habitual training time-of-day and PERIOD3 (PER3) variable number tandem repeat genotype.

93 citations


Journal ArticleDOI
TL;DR: Women show a Cr similar to men of similar body mass, despite differences in gait pattern, and the superiority of black African runners is presumably related to their leg architecture and better elastic energy storage and reuse.
Abstract: Metabolic measurement is still the criterion for investigation of the efficiency of mechanical work and for analysis of endurance performance in running. Metabolic demand may be expressed either as the energy spent per unit distance (energy cost of running, C r) or as energy demand at a given running speed (running economy). Systematic studies showed a range of costs of about 20 % between runners. Factors affecting C r include body dimensions: body mass and leg architecture, mostly calcaneal tuberosity length, responsible for 60–80 % of the variability. Children show a higher C r than adults. Higher resting metabolism and lower leg length/stature ratio are the main putative factors responsible for the difference. Elastic energy storage and reuse also contribute to the variability of C r. The increase in C r with increasing running speed due to increase in mechanical work is blunted till 6–7 m s−1 by the increase in vertical stiffness and the decrease in ground contact time. Fatigue induced by prolonged or intense running is associated with up to 10 % increased C r; the contribution of metabolic and biomechanical factors remains unclear. Women show a C r similar to men of similar body mass, despite differences in gait pattern. The superiority of black African runners is presumably related to their leg architecture and better elastic energy storage and reuse.

87 citations


Journal ArticleDOI
TL;DR: Sauna bathing following normal training largely expanded PV in well-trained cyclists after just four exposures, and the utility of HR and HRV indices for tracking changes in PV was uncertain.
Abstract: We investigated the effect of post-exercise sauna bathing on plasma volume (PV) expansion and whether such responses can be tracked by changes in heart rate (HR)-based measures. Seven, well-trained male cyclists were monitored for 35 consecutive days (17 days baseline training, 10 days training plus sauna, 8 days training). Sauna exposure consisted of 30 min (87 °C, 11 % relative humidity) immediately following normal training. Capillary blood samples were collected while resting seated to assess PV changes. HR (HRwake) and vagal-related HR variability (natural logarithm of square root mean squared differences of successive R–R intervals, ln rMSSDwake) were assessed daily upon waking. A sub-maximal cycle test (5 min at 125 W) was performed on days 1, 8, 15, 22, 25, 29, and 35 and HR recovery (HRR60s) and ln rMSSDpostex were assessed post-exercise. Effects were examined using magnitude-based inferences. Compared with baseline, sauna resulted in: (1) peak PV expansion after four exposures with a likely large increase [+17.8 % (90 % confidence limits, 7.4; 29.2)]; (2) reduction of HRwake by a trivial-to-moderate amount [−10.2 % (−15.9; −4.0)]; (3) trivial-to-small changes for ln rMSSDwake [4.3 % (1.9; 6.8)] and ln rMSSDpostex [−2.4 % (−9.1; 4.9)]; and (4) a likely moderate decrease in HRR60s [−15.6 % (−30.9; 3.0)]. Correlations between individual changes in PV and HR measures were all unclear. Sauna bathing following normal training largely expanded PV in well-trained cyclists after just four exposures. The utility of HR and HRV indices for tracking changes in PV was uncertain. Future studies will clarify mechanisms and performance benefits of post-training sauna bathing.

83 citations


Journal ArticleDOI
TL;DR: Seven-day intake of New Zealand blackcurrant extract improves 16.1 km cycling time-trial performance and increases fat oxidation during moderate intensity cycling.
Abstract: PURPOSE: Blackcurrant intake increases peripheral blood flow in humans, potentially by anthocyanin-induced vasodilation which may affect substrate delivery and exercise performance. We examined the effects of New Zealand blackcurrant (NZBC) extract on substrate oxidation, cycling time-trial performance and plasma lactate responses following the time-trial in trained cyclists. METHODS: Using a randomized, double-blind, crossover design, fourteen healthy men (age: 38 ± 13 years, height: 178 ± 4 cm, body mass: 77 ± 9 kg, VO2max: 53 ± 6 ml·kg-1·min-1, mean ± SD) ingested NZBC extract (300 mg∙day-1 CurraNZ™ containing 105 mg anthocyanin) or placebo (PL, 300 mg microcrystalline cellulose M102) for 7-days (washout 14-days). On day 7, participants performed 30 min of cycling (3x10 min at 45, 55 and 65% VO2max), followed by a 16.1 km time-trial with lactate sampling during a 20-minute passive recovery. RESULTS: NZBC extract increased fat oxidation at 65% VO2max by 27% (P < 0.05) and improved 16.1 km time-trial performance by 2.4% (NZBC: 1678 ± 108 s, PL: 1722 ± 131 s, P < 0.05). Plasma lactate was higher with NZBC extract immediately following the time-trial (NZBC: 7.06 ± 1.73 mmol∙L-1, PL: 5.92 ± 1.58 mmol∙L-1 P < 0.01). CONCLUSIONS: Seven days intake of New Zealand blackcurrant extract improves 16.1 km cycling time-trial performance and increases fat oxidation during moderate intensity cycling.

80 citations


Journal ArticleDOI
TL;DR: Regular moderate physical activity enhances liver health and cross-sectional and longitudinal studies show that regular exercise can reduce hepatic fat, but the effect on circulating aminotransferases is unclear and the modality and dose of physical activity optimizing health benefits need clarification.
Abstract: To review the responses of the liver to acute and chronic physical activity and to summarize relationships between physical activity and liver health. A systematic search of HealthStar/Ovid from 1975 through June of 2013, supplemented by articles from other sources. 351 of 8,010 articles identified by HealthStar/Ovid were supplemented by 92 other papers; after focussing, the review was reduced to 435 citations. Prolonged acute exercise reduces hepatic blood flow, stimulating hepatic glycogenolysis, gluconeogenesis and synthesis of some proteins; however, lipid metabolism shows little change. Glutathione depletion suggests oxidative stress. Enzymes affecting carbohydrate metabolism are up-regulated, and lipogenic enzymes are down-regulated. The main triggers are humoral, but hepatic afferent nerves, cytokines, reactive oxygen species, and changes in hepatic blood flow may all play some role. Regular aerobic exercise training improves blood glucose control during exercise by increasing glycogen stores and up-regulating enzymes involved in gluconeogenesis and carbohydrate metabolism. Resistance to oxidant stress is generally increased by training. Lipogenic enzymes are down-regulated, and lipid metabolism is augmented. Modulations of insulin, insulin-like growth factor, glucagon and interleukin-6 may trigger the adaptive responses to training. Cross-sectional and longitudinal studies show that regular exercise can reduce hepatic fat, but the effect on circulating aminotransferases is unclear and the modality and dose of physical activity optimizing health benefits need clarification. Regular moderate physical activity enhances liver health. Adverse functional changes can develop if habitual activity is inadequate, and extremely prolonged competitive exercise may also be harmful, particularly under harsh environmental conditions.

Journal ArticleDOI
TL;DR: It is concluded that theracurmin ingestion attenuates some aspects of muscle damage such as MVC loss and CK activity increase.
Abstract: Polyphenolic curcumin is known to have potent anti-inflammatory effects; thus the present study investigated the hypothesis that curcumin ingestion would attenuate muscle damage after eccentric exercise Fourteen untrained young men (24 ± 1 years) performed 50 maximal isokinetic (120°/s) eccentric contractions of the elbow flexors of one arm on an isokinetic dynamometer and the same exercise with the other arm 4 weeks later They took 150 mg of curcumin (theracurmin) or placebo (starch) orally before and 12 h after each eccentric exercise bout in a randomised, crossover design Maximal voluntary contraction (MVC) torque of the elbow flexors, range of motion of the elbow joint, upper-arm circumference, muscle soreness, serum creatine kinase (CK) activity, and plasma interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) concentration were measured before, immediately after, and 24, 48, 72 and 96 h after each eccentric exercise Changes in these variables over time were compared between curcumin and placebo conditions by two-way repeated measures ANOVA MVC torque decreased smaller and recovered faster (eg, 4 days post-exercise: −31 ± 13 % vs −15 ± 15 %), and peak serum CK activity was smaller (peak: 7684 ± 8959 IU/L vs 3398 ± 3562 IU/L) for curcumin than placebo condition (P < 005) However, no significant differences between conditions were evident for other variables, and no significant changes in IL-6 and TNF-α were evident after exercise It is concluded that theracurmin ingestion attenuates some aspects of muscle damage such as MVC loss and CK activity increase

Journal ArticleDOI
TL;DR: While the NLMF literature is conflicting, certain variables appear to affect NLMF responses which can account for some of the discrepancies and it appears that NLMF effects may be muscle group dependent.
Abstract: Non-local muscle fatigue (NLMF) is characterized by muscle performance impairments in a contralateral or remote non-exercised muscle(s) following a fatiguing protocol of a different muscle group(s) This topic is of interest as it affords insights into physiological determinants of muscle fatigue and may provide practical applications concerning the order of exercises in training and rehabilitation programs A literature review was conducted using Web of Science, PubMed, and Google Scholar databases to evaluate the NLMF effects and possible underlying mechanisms Overall, 35 studies with 58 outcome measures that met the inclusion criteria were identified The literature is conflicting with approximately half of the studies reporting NLMF effects (32 of 58 measurements) However, on closer examination 76 % of outcome measures of the lower limbs reported NLMF effects (23 of 30 measurements) compared to only 32 % in the upper body (9 of 28 measurements) Thus, it appears that NLMF effects may be muscle group dependent Also, tests that involve prolonged or repetitive contractions provide clearer evidence of NLMF Other variables potentially influencing the size of the NLMF effect include the fatigued muscle groups, the protocols used to elicit the fatigue, gender and training background of participants While the NLMF literature is conflicting, certain variables appear to affect NLMF responses which can account for some of the discrepancies Furthermore, the NLMF effects may be attributed to four different but interconnected pathways: neurological, biochemical, biomechanical and psychological

Journal ArticleDOI
TL;DR: Near identical responses in performance and physiological parameters between mental fatigue and control conditions suggest that peripheral mechanisms primarily regulate maximal anaerobic exercise.
Abstract: Mental fatigue can negatively impact on submaximal endurance exercise and has been attributed to changes in perceived exertion rather than changes in physiological variables. The impact of mental fatigue on maximal anaerobic performance is, however, unclear. Therefore, the aim of the present study was to induce a state of mental fatigue to examine the effects on performance, physiological and perceptual variables from subsequent tests of power, strength and anaerobic capacity. Twelve participants took part in the single-blind, randomised, crossover design study. Mental fatigue was induced by 90 min of the computer-based Continuous Performance Task AX version. Control treatment consisted of 90 min of watching emotionally neutral documentaries. Participants consequently completed countermovement jump, isometric leg extension and a 3-min all-out cycling tests. Results of repeated measures analysis of variance and paired t tests revealed no difference in any performance or physiological variable. Rating of perceived exertion tended to be greater when mentally fatigued (mental fatigue = 19 ± 1 vs control = 18 ± 1, p = 0.096, $$\eta^{2}_{\text{p}}$$ = .232) and intrinsic motivation reduced (mental fatigue = 11 ± 4 vs control = 13 ± 6, p = 0.063, d = 0.597) in the mental fatigue condition. Near identical responses in performance and physiological parameters between mental fatigue and control conditions suggest that peripheral mechanisms primarily regulate maximal anaerobic exercise. Whereas mental fatigue can negatively impact submaximal endurance exercise, it appears that explosive power, voluntary maximal strength and anaerobic work capacity are unaffected.

Journal ArticleDOI
TL;DR: It is demonstrated that REHIT is associated with a pronounced disturbance of physiological homeostasis and associated activation of signalling pathways, which together may help explain previously observed adaptations once considered exclusive to aerobic exercise.
Abstract: We have previously shown that 6 weeks of reduced-exertion high-intensity interval training (REHIT) improves $$\dot{V}{\text{O}}_{2}$$ max in sedentary men and women and insulin sensitivity in men. Here, we present two studies examining the acute physiological and molecular responses to REHIT. In Study 1, five men and six women (age: 26 ± 7 year, BMI: 23 ± 3 kg m−2, $$\dot{V}{\text{O}}_{2}$$ max: 51 ± 11 ml kg−1 min−1) performed a single 10-min REHIT cycling session (60 W and two 20-s ‘all-out’ sprints), with vastus lateralis biopsies taken before and 0, 30, and 180 min post-exercise for analysis of glycogen content, phosphorylation of AMPK, p38 MAPK and ACC, and gene expression of PGC1α and GLUT4. In Study 2, eight men (21 ± 2 year; 25 ± 4 kg·m−2; 39 ± 10 ml kg−1 min−1) performed three trials (REHIT, 30-min cycling at 50 % of $$\dot{V}{\text{O}}_{2}$$ max, and a resting control condition) in a randomised cross-over design. Expired air, venous blood samples, and subjective measures of appetite and fatigue were collected before and 0, 15, 30, and 90 min post-exercise. Acutely, REHIT was associated with a decrease in muscle glycogen, increased ACC phosphorylation, and activation of PGC1α. When compared to aerobic exercise, changes in $$\dot{V}{\text{O}}_{2}$$ , RER, plasma volume, and plasma lactate and ghrelin were significantly more pronounced with REHIT, whereas plasma glucose, NEFAs, PYY, and measures of appetite were unaffected. Collectively, these data demonstrate that REHIT is associated with a pronounced disturbance of physiological homeostasis and associated activation of signalling pathways, which together may help explain previously observed adaptations once considered exclusive to aerobic exercise.

Journal ArticleDOI
TL;DR: Results of the present study suggest that low to moderate exercise intensity does not alter Executive functioning, but that exercise impairs cognitive functions (Executive and non-Executive) when the physical workload becomes heavy.
Abstract: To assess the relationship between exercise intensity, cerebral HbO2 and cognitive performance (Executive and non-Executive) in young adults. We measured reaction time (RT) and accuracy, during a computerized Stroop task, in 19 young adults (7 males and 12 females). Their mean ± SD age, height, body mass and body mass index (BMI) were 24 ± 4 years, 1.67 ± 0.07 m, 72 ± 14 kg and 25 ± 3 kg m−2, respectively. Each subject performed the Stroop task at rest and during cycling at exercise of low intensity [40 % of peak power output (PPO)], moderate intensity (60 % of PPO) and high intensity (85 % of PPO). Cerebral oxygenation was monitored during the resting and exercise conditions over the prefrontal cortex (PFC) using near-infrared spectroscopy (NIRS). High-intensity exercise slowed RT in both the Naming (p = 0.04) and the Executive condition (p = 0.04). The analysis also revealed that high-intensity exercise was associated with a decreased accuracy when compared to low-intensity exercise (p = 0.021). Neuroimaging results confirm a decrease of cerebral oxygenation during high-intensity exercise in comparison to low- (p = 0.004) and moderate-intensity exercise (p = 0.003). Correlations revealed that a lower cerebral HbO2 in the prefrontal cortex was associated with slower RT in the Executive condition only (p = 0.04, g = −0.72). Results of the present study suggest that low to moderate exercise intensity does not alter Executive functioning, but that exercise impairs cognitive functions (Executive and non-Executive) when the physical workload becomes heavy. The cerebral HbO2 correlation suggests that a lower availability of HbO2 was associated with slower RT in the Executive condition only.

Journal ArticleDOI
TL;DR: Findings demonstrate that stimulation of the M1 using tDCS does not induce analgesia during exercise, suggesting that the processing of pain produced via classic measures of experimental pain (i.e., a CPT) is different to that of EIP.
Abstract: Transcranial direct current stimulation (tDCS) provides a new exciting means to investigate the role of the brain during exercise. However, this technique is not widely used in exercise science, with little known regarding effective electrode montages. This study investigated whether tDCS of the motor cortex (M1) would elicit an analgesic response to exercise-induced pain (EIP). Nine participants completed a VO2max test and three time to exhaustion (TTE) tasks on separate days following either 10 min 2 mA tDCS of the M1, a sham or a control. Additionally, seven participants completed 3 cold pressor tests (CPT) following the same experimental conditions (tDCS, SHAM, CON). Using a well-established tDCS protocol, tDCS was delivered by placing the anodal electrode above the left M1 with the cathodal electrode above dorsolateral right prefrontal cortex. Gas exchange, blood lactate, EIP and ratings of perceived exertion (RPE) were monitored during the TTE test. Perceived pain was recorded during the CPT. During the TTE, no significant differences in time to exhaustion, RPE or EIP were found between conditions. However, during the CPT, perceived pain was significantly (P < 0.05) reduced in the tDCS condition (7.4 ± 1.2) compared with both the CON (8.6 ± 1.0) and SHAM (8.4 ± 1.3) conditions. These findings demonstrate that stimulation of the M1 using tDCS does not induce analgesia during exercise, suggesting that the processing of pain produced via classic measures of experimental pain (i.e., a CPT) is different to that of EIP. These results provide important methodological advancement in developing the use of tDCS in exercise.

Journal ArticleDOI
TL;DR: Low-load resistance exercise to exhaustion is an effective method for promoting muscle swelling regardless of BFR and NBFR, and the increase in muscle swelling for both NBFR and BFR is maintained even 60 min after the exercise.
Abstract: The effects on muscle swelling were compared between low-load resistance exercise to exhaustion with (BFR) and without blood flow restriction (NBFR). Ten young men [aged 27 (SD 5) years, standing height 1.74 (SD 0.05) m, body mass 70.3 (SD 4.3) kg] performed 20 % of one repetition maximal dumbbell curl exercise to exhaustion (four sets, rest intervals were 30 s for BFR and/or 3 min for NBFR, respectively). One arm was randomly chosen for BFR exercise and the other arm performed NBFR exercise. During the BFR exercise session, an elastic cuff was worn proximally on the testing arm at 160 mmHg. Electromyography (EMG) signals were recorded from surface electrodes placed on the biceps brachii muscle and analyzed for integrated EMG (iEMG). Biceps brachii muscle thickness (MTH) was measured using B-mode ultrasound. The total number of exercise repetitions was greater (p < 0.01) in NBFR (221 ± 67 reps) than in BFR (111 ± 36 reps). During the exercise session, iEMG for biceps brachii muscles increased (p < 0.01) during BFR and NBFR (3.94 and 4.45 times of baseline value). Immediately after the exercise, MTH sharply increased (p < 0.01) with BFR and NBFR (1.21 and 1.20 times of baseline value). These results demonstrate that both BFR and NBFR exercises lead to pronounced muscle activation and muscle swelling. Low-load resistance exercise to exhaustion is an effective method for promoting muscle swelling regardless of BFR. Furthermore, our data indicate that the increase in muscle swelling for both NBFR and BFR is maintained even 60 min after the exercise.

Journal ArticleDOI
TL;DR: The effects of stretching on joint passive torque do not reflect changes in the medial gastrocnemius shear elastic modulus, and these responses to stretching depend on its intensity.
Abstract: We investigated the effects of plantarflexor static stretching of different intensities on the medial gastrocnemius (GAS) shear elastic modulus, GAS fascicle length and ankle passive torque–angle responses during and after stretching. Participants performed three stretching sessions of different intensities: 40 % (R40) of maximal dorsiflexion range of motion (ROM), 60 % (R60) of ROM, and 80 % (R80) of ROM. Each stretching lasted 10 min. The GAS architecture, GAS shear elastic modulus, ankle passive torque–angle, and muscle activity were assessed before, during, and after the stretching. The absolute and relative (i.e., normalized to the static stretching start value) GAS shear elastic modulus relaxation varied across stretching intensities. The absolute passive torque relaxation varied across intensities (p < 0.05) but not when normalized to the stretching start value. No significant changes were observed in GAS fascicle length during the stretching (p = 0.93). After stretching, passive torque at a given angle was significantly decreased for R60 [−0.99 ± 0.59 Nm (−6.5 ± 3.8 %), p < 0.001] and R80 [−1.05 ± 1.12 Nm (−6.8 ± 6.3 %), p = 0.004], and GAS shear elastic modulus decreased only for the R80 [−9.3 ± 7.2 kPa (−14.1 %), p = 0.003]. No significant correlations were found between the magnitude of relaxation during stretching and post-stretching effect in the GAS shear elastic modulus or ankle passive torque variables. No significant relation was found between the shear elastic modulus and the ankle passive torque responses during and after stretching. The effects of stretching on joint passive torque do not reflect changes in the medial gastrocnemius shear elastic modulus, and these responses to stretching depend on its intensity.

Journal ArticleDOI
TL;DR: The findings add to the evidence that the linear F–V and, consequently, parabolic P–V models could be used to study the mechanical properties of muscular systems, as well as to design a relatively simple, reliable, and ecologically valid routine test of the muscle ability of force, power, and velocity production.
Abstract: A number of recent studies have revealed an approximately linear force–velocity (F–V) and, consequently, a parabolic power–velocity (P–V) relationship of multi-joint tasks. However, the measurement characteristics of their parameters have been neglected, particularly those regarding arm muscles, which could be a problem for using the linear F–V model in both research and routine testing. Therefore, the aims of the present study were to evaluate the strength, shape, reliability, and concurrent validity of the F–V relationship of arm muscles. Twelve healthy participants performed maximum bench press throws against loads ranging from 20 to 70 % of their maximum strength, and linear regression model was applied on the obtained range of F and V data. One-repetition maximum bench press and medicine ball throw tests were also conducted. The observed individual F–V relationships were exceptionally strong (r = 0.96–0.99; all P 0.80), while their concurrent validity regarding directly measured F, P, and V ranged from high (for maximum F) to medium-to-low (for maximum P and V). The findings add to the evidence that the linear F–V and, consequently, parabolic P–V models could be used to study the mechanical properties of muscular systems, as well as to design a relatively simple, reliable, and ecologically valid routine test of the muscle ability of force, power, and velocity production.

Journal ArticleDOI
TL;DR: The results indicate that cfDNA liberated in response to acute physical exercise is not released by vesicular means and circulates in a soluble form in blood plasma which could indicate different biological functions exerted by cfDNA and EVs.
Abstract: Strenuous exercise induces a rapid and transient elevation of cell free DNA (cfDNA) concentration in blood plasma. The detection of cfDNA in the presence of plasma nucleases could indicate an association of cfDNA with protective vesicular structures. Several cell types release extracellular vesicles (EVs), including exosomes and shedding microvesicles, which are known to mediate the exchange of proteins and nucleic acids (largely RNA) between cells. Here, we assessed whether EVs play a role in the exercise-dependent release of cfDNA in blood plasma. Venous blood collected from healthy volunteers before and after incremental treadmill exercise was separated into vesicular (EV) and soluble fractions. Nuclear and mitochondrial DNA content in plasma supernatants and EV fractions was determined by quantitative real-time PCR (qPCR). We show that the majority of cfDNA is located in the plasma supernatants. Only minute amounts of DNA were observed in the EV-associated fractions including microvesicles and exosomes. Nuclear and mitochondrial DNA species differ in terms of their quantities in the several plasma fractions. Our results indicate that cfDNA liberated in response to acute physical exercise is not released by vesicular means and circulates in a soluble form in blood plasma which could indicate different biological functions exerted by cfDNA and EVs. The different nature of DNA species in plasma has major implications for the preparation of plasma and other bodily fluids prior to analysis.

Journal ArticleDOI
TL;DR: This study suggests 8 weeks of periodized high-intensity strength RT with shortened RI induces significantly greater enhancements in body composition, muscular performance, and functional performance, compared to the same RT prescription with extended RI, in older men.
Abstract: Purpose To determine if 8 weeks of periodized strength resistance training (RT) utilizing relatively short rest interval lengths (RI) in between sets (SS) would induce greater improvements in body composition and muscular performance, compared to the same RT program utilizing extended RI (SL).

Journal ArticleDOI
TL;DR: The sequential peak activity of MTP flexors followed by MTP extensors suggests that their biomechanical contributions may be largely separable from each other and from other extrinsic foot muscles during walking.
Abstract: The human foot undergoes complex deformations during walking due to passive tissues and active muscles. However, based on prior recordings it is unclear if muscles that contribute to flexion/extension of the metatarsophalangeal (MTP) joints are activated synchronously to modulate joint impedance, or sequentially to perform distinct biomechanical functions. We investigated the coordination of MTP flexors and extensors with respect to each other, and to other ankle–foot muscles. We analyzed surface electromyographic (EMG) recordings of intrinsic and extrinsic foot muscles for healthy individuals during level treadmill walking, and also during sideways and tiptoe gaits. We computed stride-averaged EMG envelopes and used the timing of peak muscle activity to assess synchronous vs. sequential coordination. We found that peak MTP flexor activity occurred significantly before peak MTP extensor activity during walking (P < 0.001). The period around stance-to-swing transition could be roughly characterized by sequential peak muscle activity from the ankle plantarflexors, MTP flexors, MTP extensors, and then ankle dorsiflexors. We found that foot muscles that activated synchronously during forward walking tended to dissociate during other locomotor tasks. For instance, extensor hallucis brevis and extensor digitorum brevis muscle activation peaks decoupled during sideways gait. The sequential peak activity of MTP flexors followed by MTP extensors suggests that their biomechanical contributions may be largely separable from each other and from other extrinsic foot muscles during walking. Meanwhile, the task-specific coordination of the foot muscles during other modes of locomotion indicates a high-level of specificity in their function and control.

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TL;DR: The increase in JV, PV, and FV cross-sectional area during spaceflight confirmed that there was venous blood pooling in the cephalic, splanchnic, and pelvic regions.
Abstract: To determine if 6 months in microgravity resulted in significant changes in the major central and peripheral veins indicating a redistribution of venous blood flow. Ten astronauts participated in the study. Jugular vein (JV), portal vein (PV), femoral vein (FV), tibial vein (TibV), and gastrocnemius vein (Gast V) were assessed by echography for the measurement of vessel cross-sectional area. Inflight exams were conducted by astronauts using a volume capture method in which images collected were processed to produce a 3D reconstruction of the vessel which was later analyzed by a trained sonographer. Measurements were conducted pre-flight, at the beginning of the flight (day 15), near the end of the flight (4–5.5 months), and post-flight. During the flight, JV, PV, JV/PV ratio, and FV were found significantly increased from pre-flight at 15 days and 4–5.5 months (JV: 178 and 225 %, p < 0.05; PV: 36 and 45 %, p < 0.05; JV/PV ratio: 102 and 120 %, p < 0.05; FV: 124 and 169 %, p < 0.05). Conversely, calf veins decreased at day 15 and at 4–5.5 months (TibV: −45 % and−52 %, p < 0.05; Gast V: −68 and −55 %, p < 0.05). All veins returned to base line conditions 4 days after returning to Earth. The increase in JV, PV, and FV cross-sectional area during spaceflight confirmed that there was venous blood pooling in the cephalic, splanchnic, and pelvic regions. Further investigation is needed to determine the consequences of this fluid stagnation on the brain, eye, splanchnic, and pelvic organ morphology and or function.

Journal ArticleDOI
TL;DR: There is a decline in the EEG response to exercise in the PFC following the RCP, whilst alpha activity in the MC is preferentially maintained; therefore, changes within the P FC appear to play a role in exercise termination.
Abstract: The purpose of this study was to measure the EEG response in the prefrontal cortex (PFC) and motor cortex (MC) during incremental exercise and align these responses with ventilatory parameters. The EEG activity at the motor (MC) and frontal cortices was measured during an incremental exercise test (IET) in 11 cyclists (peak oxygen uptake $$\left( {\dot{V}{\text{O}}_{{2 {\text{peak}}}} } \right)$$ 4.1 ± 0.74 (SD) L min−1). EEG power spectral densities were calculated for alpha slow (αS) (8–10 Hz), alpha fast, (αF) (10–13 Hz), Beta (β) (13–30 Hz), and Gamma (γ) (30–40 Hz). EEG data were calculated as % change from eyes open (EO) baseline and a repeated measures analysis of variance (ANOVA) was performed on regions of interest (ROI), time and bandwidth. All EEG activity increased from 50 % $$\dot{V}{\text{O}}_{{ 2 {\text{peak}}}}$$ to ventilatory threshold (VT) (P = 0.045) and respiratory compensation point (RCP) (P = 0.019) and decreased from RCP to end of exercise (END) (P = 0.04). Significant differences between regions were found at the VLPFC and MC for both αS and αF. αS and αF increased from 50 % $$\dot{V}{\text{O}}_{{ 2 {\text{peak}}}}$$ to RCP (14.9 ± 10.2 to 23.8 ± 15.5 and 18.9 ± 10.6 to 26.12 ± 12.7, respectively) and then decreased to END (23.8 ± 15.5 to 14.4 ± 10.3 and 26.1 ± 12.7, to 17.7 ± 8.8, respectively) (P < 0.01) and concomitantly only decreased significantly in MC in αF from VT to END (P < 0.05). There is a decline in the EEG response to exercise in the PFC following the RCP, whilst alpha activity in the MC is preferentially maintained; therefore, changes within the PFC appear to play a role in exercise termination.

Journal ArticleDOI
TL;DR: 15 weeks of soccer training with sedentary middle-aged women caused marked increases in bone turnover markers, with concomitant increases in leg bone mass, as well as prolonged submaximal or high-intensity intermittent swimming training.
Abstract: Purpose The present study examined the effects of 15 weeks of soccer training and two different swimming training protocols on bone turnover in sedentary middle-aged women.

Journal ArticleDOI
TL;DR: Even one session of plyometric exercises appear to stimulate bone formation in boys and men, as reflected by the increase in bone ALP and OPG, suggesting that during growth, cellular bone activities respond with greater magnitude to mechanical stimuli.
Abstract: The acute exercise effects on bone markers in adults are unclear, while in children, there are no such data. To investigate the acute response of biochemical markers of bone turnover to a high-impact exercise session consisting of high-mechanical loading in boys and young men. Twelve boys (10.2 ± 0.4 years) and 14 men (22.0 ± 0.8 years) underwent a protocol of plyometric jumping exercises (total 144 jumps). Venous blood samples were collected pre-, 5 min, 1 and 24 h post-exercise, and analyzed for markers of bone formation and resorption: bone-specific alkaline phosphatase (bone ALP), osteoprotegerin (OPG), amino-terminal cross-linking telopeptide (NTx), and receptor activator of nuclear factor kappa beta ligand (RANKL). Boys had higher resting bone ALP (111.9 ± 29.2 vs. 30.6 ± 11.2 µg/L, p < 0.05) and NTx levels (49.8 ± 13.2 vs. 21.7 ± 5.9 nM BCE, p < 0.05) than men but no group differences were observed in resting OPG or RANKL. Following exercise (24 h), bone ALP and NTx increased in both boys and men (bone ALP: 24.1 vs. 9.9 %, respectively; NTx: 23.5 vs. −5 %, respectively), although the group-by-time interaction was not statistically significant. OPG increased significantly (p < 0.05) in both groups (5.7 and 16.1 %, respectively). Even one session of plyometric exercises appear to stimulate bone formation in boys and men, as reflected by the increase in bone ALP and OPG. The boys’ response appears more pronounced than the men’s, suggesting that during growth, cellular bone activities respond with greater magnitude to mechanical stimuli.

Journal ArticleDOI
TL;DR: Findings suggest an important role of estradiol in blunting the muscle damage response to intense eccentric exercise and preserving muscle function after EiMD.
Abstract: To examine the influence of estradiol on muscle damage and leg strength after intense eccentric exercise Eight men (MEN), eight normally menstruating women (WomenNM), and eight women using oral contraceptives (WomenOC) participated in this study Subjects performed 240 maximal-effort bilateral eccentric contractions of the quadriceps muscle groups designed to elicit exercise-induced muscle damage (EiMD) Serum creatine kinase (CK), myoglobin (Mb), and fatty acid-binding protein (FABP) concentrations were measured before (pre-) EiMD, as well as 0, 6, 24, and 48 h post-EiMD Peak isometric quadriceps torque (ie, leg strength) was measured pre-EiMD, as well as 24 and 48 h post-EiMD The increases in CK, Mb, and FABP concentrations from pre- to post-EiMD were greater in MEN (10-fold, 15-fold, and fourfold, respectively) and WomenOC (sevenfold, 11-fold, and ninefold) compared with WomenNM (five-, six-, and threefold; p < 005) The decline in leg strength was about 10 % pre- to 24 h post-EiMD in all groups and decreased a further 10–15 % by 48 h post-EiMD in the MEN and WomenOC only Our findings suggest an important role of estradiol in blunting the muscle damage response to intense eccentric exercise and preserving muscle function after EiMD

Journal ArticleDOI
TL;DR: The repeated anaerobic sprint test leads to substantial alterations in stride mechanics and leg-spring behaviour and the link between repeated-sprint ability and the change in neuromuscular activation as well as in muscle de- and re-oxygenation rates is strengthened.
Abstract: This study aimed to determine the neuro-mechanical and metabolic adjustments in the lower limbs induced by the running anaerobic sprint test (the so-called RAST). Eight professional football players performed 6 × 35 m sprints interspersed with 10 s of active recovery on artificial turf with their football shoes. Sprinting mechanics (plantar pressure insoles), root mean square activity of the vastus lateralis (VL), rectus femoris (RF), and biceps femoris (BF) muscles (surface electromyography, EMG) and VL muscle oxygenation (near-infrared spectroscopy) were monitored continuously. Sprint time, contact time and total stride duration increased from the first to the last repetition (+17.4, +20.0 and +16.6 %; all P 0.05), decreased over sprint repetitions and were correlated with the increase in running time (r = −0.82 and −0.90; both P < 0.05). Together with a better maintenance of RF and BF muscles activation levels over sprint repetitions, players with a better repeated-sprint performance (lower cumulated times) also displayed faster muscle de- (during sprints) and re-oxygenation (during recovery) rates (r = −0.74 and −0.84; P < 0.05 and 0.01, respectively). The repeated anaerobic sprint test leads to substantial alterations in stride mechanics and leg-spring behaviour. Our results also strengthen the link between repeated-sprint ability and the change in neuromuscular activation as well as in muscle de- and re-oxygenation rates.

Journal ArticleDOI
TL;DR: Data support aerobic exercise being a more appropriate BFRE for prescription in older adults that may contribute to limiting the effects of age-related muscle atrophy.
Abstract: Light-load blood flow restriction exercise (BFRE) may provide a novel training method to limit the effects of age-related muscle atrophy in older adults. Therefore, the purpose of this study was to compare the haemodynamic response to resistance and aerobic BFRE between young adults (YA; n = 11; 22 ± 1 years) and older adults (OA; n = 13; 69 ± 1 years). On two occasions, participants completed BFRE or control exercise (CON). One occasion was leg press (LP; 20 % 1-RM) and the other was treadmill walking (TM; 4 km h−1). Haemodynamic responses (HR, $$\dot{Q}$$ , SV and BP) were recorded during baseline and exercise. At baseline, YA and OA were different for some haemodynamic parameters (e.g. BP, SV). The relative responses to BFRE were similar between YA and OA. Blood pressures increased more with BFRE, and also for LP over TM. $$\dot{Q}$$ increased similarly for BFRE and CON (in both LP and TM), but with elevated HR and reduced SV (TM only). While BFR conferred slightly greater haemodynamic stress than CON, this was lower for walking than leg-press exercise. Given similar response magnitudes between YA and OA, these data support aerobic exercise being a more appropriate BFRE for prescription in older adults that may contribute to limiting the effects of age-related muscle atrophy.