Min Of Recovery Research Articles

Practical internal and external cooling methods do not influence rapid recovery from simulated taekwondo performance

Background/ObjectivesThe influence of post-exercise cooling on recovery has gained much attention in the empirical literature, however, data is limited in regards to optimizing recovery from taekwondo performance when combat is repeated in quick succession within the same day. The aim of this study was therefore to compare the effects of external and internal cooling after simulated taekwondo combat upon intestinal temperature (Tint), psychomotor skills (reaction time, response time, movement time), and neuromuscular function (peak torque, average power, time to reach peak torque). MethodsUsing a randomized counterbalanced crossover design, 10 well-trained male taekwondo athletes completed four recovery methods on separate occasions: passive recovery (CON), a 5-minute thermoneutral water immersion (35°C) (TWI), a 5-min cold water immersion (15°C) (CWI), and ice slurry ingestion (-1°C) (ICE; consumed every 5 min for 30 min). Heart rate (HR), blood lactate (Blac) concentrations, and Tint were determined at rest, immediately after combat, and at selected intervals during a 90-min recovery period. Neuromuscular functional (measured with isokinetic dynamometer) and psychomotor indices were assessed at baseline and after the recovery period. ResultsICE led to a significantly lower Tint at 30 min (P<0.01) and 45 min (P<0.01) after simulated combat; 15-30 min after cessation of ingesting ice slurry, compared with the CON and TWI conditions, respectively. However, there were no differences in Tint across time points between the other conditions (P>0.05). Psychomotor skills and neuromuscular function indices returned to baseline values after the 90 min recovery period (P>0.05) with no differences observed between conditions (P>0.05). ConclusionThe present findings suggest that internal (ICE) and external (CWI) recovery methods appear to have little impact on physiological and functional indices over the time course required to influence repeated taekwondo combat performance.

Myoelectric activity during electromagnetic resistance alone and in combination with variable resistance or eccentric overload

The purpose of this study was to compare the effects of electromagnetic resistance alone, as well as in combination with variable resistance or accentuated eccentric methods, with traditional dynamic constant external resistance exercise on myoelectric activity during elbow flexion. The study employed a within-participant randomized, cross-over design whereby 16 young, resistance-trained male and female volunteers performed elbow flexion exercise under each of the following conditions: using a dumbbell (DB); using a commercial electromagnetic resistance device (ELECTRO); variable resistance (VR) using a setting on the device that attempts to match the level of resistance to the human strength curve, and; eccentric overload (EO) using a setting on the device that increases the load by 50% on the eccentric portion of each repetition. Surface electromyography (sEMG) was obtained for the biceps brachii, brachioradialis and anterior deltoid on each of the conditions. Participants performed the conditions at their predetermined 10 repetition maximum. " The order of performance for the conditions was counterbalanced, with trials separated by a 10-min recovery period. The sEMG was synced to a motion capture system to assess sEMG amplitude at elbow joint angles of 30°, 50°, 70°, 90°, 110°, with amplitude normalized to the maximal activation. The anterior deltoid showed the largest differences in amplitude between conditions, where median estimates indicated greater concentric sEMG amplitude (~ 7–10%) with EO, ELECTRO and VR compared with DB. Concentric biceps brachii sEMG amplitude was similar between conditions. In contrast, results indicated a greater eccentric amplitude with DB compared to ELECTRO and VR, but unlikely to exceed a 5% difference. Data indicated a greater concentric and eccentric brachioradialis sEMG amplitude with DB compared to all other conditions, but differences were unlikely to exceed 5%. The electromagnetic device tended to produce greater amplitudes in the anterior deltoid, while DB tended to produce greater amplitudes in the brachioradialis; amplitude for the biceps brachii was relatively similar between conditions. Overall, any observed differences were relatively modest, equating to magnitudes of ~ 5% and not likely greater than 10%. These differences would seem to be of minimal practical significance.

The field study about the effects of artificial CO2-rich cool-water immersion after outdoor sports activity in a hot environment

Background/ObjectivesIn our previous laboratory experiment (room temperature of 25 °C), CO2-rich cool-water immersion (CCWI) suppressed subjects' core body temperature even during repeated exercise. It is unclear whether the suppression of body temperature elevation would also continue after CCWI in a hot outdoor environment. Herein we investigated the thermal effects of CCWI after regular exercise training in heat on subjects' core temperature (Tcore), three skin temperatures (Tskin), heart rate (HR), and the rate of perceived ice (RPI). MethodsThirty-six subjects (25 males, 11 females) were randomly allocated into three groups (CCWI, CWI, and control). After training at their competitive clubs, each subject was immersed up to the chest in CCWI or CWI at 20 °C for 20 min, followed by a 60-min recovery period. Tcore, Tskin, HR, and RPI were measured at the initial rest, the end of immersion, and every 10 min during the recovery period. ResultsCompared to the control, the CCWI subjects' Tcore was significantly lower at 50–60 min after the end of immersion (p < 0.05). Tskin at abdominal and lower-leg regions during the recovery period was maintained at significantly lower values in the CWI and CCWI groups versus control (p < 0.05). The CCWI subjects maintained lower Tskin for a longer time than the CWI subjects. ConclusionsThese findings indicate that CCWI suppresses the rise in body temperatures more than CWI, even in a hot environment, suggesting that CCWI may be a more effective countermeasure against increasing body temperature in a hot outdoor environment.

Effects of Low-Intensity Aerobic Exercise on Neurophysiological and Behavioral Correlates of Cognitive Function.

Acute aerobic exercise exerts a small beneficial effect on cognition. Previous research primarily examines cognitive changes following a bout of exercise, while little is currently known about changes in cognitive performance during exercise. The primary purpose of this study was to examine the effects of low-intensity cycling on cognitive function indexed by behavioral (response accuracy; reaction time) and neurocognitive (P3 mean amplitude; P3 centroid latency) responses. Twenty-seven (Mage = 22.9 ± 3.0 years old) individuals were counterbalanced into low-intensity exercise (EX) and seated control (SC) conditions spread across two testing sessions. During each condition, participants completed a 10 min resting baseline period, 20 min of either sustained cycling or seated rest, and a 20 min recovery period. Primary outcomes were assessed at 10 min intervals (five blocks total) throughout each condition via a modified visual oddball task while electroencephalography (EEG) responses were measured. Across time blocks, both conditions exhibited faster reaction times on frequent trials but reduced accuracy to rare trials, suggesting a speed-accuracy tradeoff. There were no differences between conditions in P3 centroid latency, whereas a significant reduction in P3 amplitude was observed during the 20 min exercise period compared to the control condition. Taken together, results suggest that exercise at lower doses may have minimal influence on behavioral outcomes of cognitive performance but may impact more basic measures of brain function. Information gathered from this study may aid in the development of appropriate exercise prescriptions for populations looking to specifically target cognitive function deficits.

Combat Sports as a Model for Measuring the Effects of Repeated Head Impacts on Autonomic Brain Function: A Brief Report of Pilot Data.

Automated pupil light reflex (PLR) is a valid indicator of dysfunctional autonomic brain function following traumatic brain injury. PLR's use in identifying disturbed autonomic brain function following repeated head impacts without outwardly visible symptoms has not yet been examined. As a combat sport featuring repeated 'sub-concussive' head impacts, mixed martial arts (MMA) sparring may provide a model to understand such changes. The aim of this pilot study was to explore which, if any, PLR variables are affected by MMA sparring. A cohort of n = 7 MMA athletes (age = 24 ± 3 years; mass = 76.5 ± 9 kg; stature = 176.4 ± 8.5 cm) took part in their regular sparring sessions (eight rounds × 3 min: 1 min recovery). PLR of both eyes was measured immediately pre- and post-sparring using a Neuroptic NPi-200. Bayesian paired samples t-tests (BF10 ≥ 3) revealed decreased maximum pupil size (BF10 = 3), decreased minimum pupil size (BF10 = 4) and reduced PLR latency (BF10 = 3) post-sparring. Anisocoria was present prior to sparring and increased post-sparring, with both eyes having different minimum and maximum pupil sizes (BF10 = 3-4) and constriction velocities post-sparring (BF10 = 3). These pilot data suggest repeated head impacts may cause disturbances to autonomic brain function in the absence of outwardly visible symptoms. These results provide direction for cohort-controlled studies to formally investigate the potential changes observed.

Local passive heating administered during recovery impairs subsequent isokinetic knee extension exercise performance

BACKGROUND: Passive heating has attracted attention as a potentially promising recovery modality in sports. However, investigations of passive heating have yielded only inconsistent results for exercise performance. OBJECTIVE: To investigate the acute effects of local passive heating administered between repeated bouts of isokinetic exercise. METHODS: The experiment was a randomized crossover study. There was a total of three visits including a familiarization visit. During the remaining two visits, eleven healthy men performed three bouts of nine sets of isokinetic knee extensions using their dominant single-leg (30 repetitions/set, 180∘/sec). A 15 min recovery, during which a local passive heating pad at control (CON) or heating (HT) was applied to the rectus femoris, was afforded after the 3rd and 6th sets (Recovery 1 and 2). Isokinetic exercise performance, as assessed by peak torque, total work, and average power was analyzed using two-way repeated-measures ANOVA. RESULTS: Following Recovery 1 and 2, isokinetic exercise performance, as assessed by peak torque, total work, and average power was reduced in Set 4 (p&lt; 0.001, p&lt; 0.001, p= 0.080) and Set 7 (p&lt; 0.001, p&lt; 0.001, p= 0.009) in the HT group relative to the CON group. Electromyography analysis revealed that signal amplitude was lower in the HT group in Set 4 (p&lt; 0.001) subsequent to Recovery 1, and that firing frequency was higher in Set 7 (p= 0.002) in the HT group after Recovery 2. Furthermore, EMG time-frequency maps from one representative participant showed that following Recovery 1 and 2 peak energy decreased during the first five repetitions in Set 4 and 7. CONCLUSIONS: Local passive heating administered during recovery decreased subsequent performance of isokinetic knee extensors, muscle activation ability and increased firing frequency maintaining force output. Therefore, local passive heating is not an appropriate acute recovery strategy for isokinetic exercises.

Capturing postural blood pressure dynamics with near-infrared spectroscopy-measured cerebral oxygenation

Orthostatic hypotension (OH) is highly prevalent in older adults and associated with dizziness, falls, lower physical and cognitive function, cardiovascular disease, and mortality. OH is currently diagnosed in a clinical setting with single-time point cuff measurements. Continuous blood pressure (BP) devices can measure OH dynamics but cannot be used for daily life monitoring. Near-infrared spectroscopy (NIRS) has potential diagnostic value in measuring cerebral oxygenation continuously over a longer time period, but this needs further validation. This study aimed to compare NIRS-measured (cerebral) oxygenation with continuous BP and transcranial Doppler-measured cerebral blood velocity (CBv) during postural changes. This cross-sectional study included 41 participants between 20 and 88 years old. BP, CBv, and cerebral (long channels) and superficial (short channels) oxygenated hemoglobin (O2Hb) were measured continuously during various postural changes. Pearson correlations between BP, CBv, and O2Hb were calculated over curves and specific characteristics (maximum drop amplitude and recovery). BP and O2Hb only showed good curve-based correlations (0.58–0.75) in the initial 30 s after standing up. Early (30–40 s) and 1-min BP recovery associated significantly with O2Hb, but no consistent associations were found for maximum drop amplitude and late (60–175 s) recovery values. Associations between CBv and O2Hb were poor, but stronger for long-channel than short-channel measurements. BP associated well with NIRS-measured O2Hb in the first 30 s after postural change. Stronger associations for CBv with long-channel O2Hb suggest that long-channel NIRS specifically reflects cerebral blood flow during postural transitions, necessary to better understand the consequences of OH such as intolerance symptoms.

Comparable effects of circuit and traditional resistance exercise on platelet α2bβ3 receptor and platelet activation and function.

Resistance exercise induces thrombocytosis and increases platelet activation and function. These changes might be related to exercise variables including exercise intensity and type. We compared the effects of traditional resistance exercise (TRE) and circuit resistance exercise (CRE) on cellular markers of platelet activation and function. In this crossover study ten healthy male (mean±SD: age, 25.6±2.4 years) subjects performed TRE encompassed 3 sets of 10 repetitions at 100% of 10-RM (10 repetition maximum) for 6 exercises, and CRE protocols included 3 sets of 10 repetitions at 100% of 10-RM for all 6 exercises consecutively, in two separate weeks. To measure platelet indices, PAC1, CD41a, CD42b and CD62P three blood samples were taken before, immediately after exercise, and after 30 min recovery. Lactate concentration, blood pressure, platelet count (PLT), and mean platelet volume (MPV) were significantly (p < 0.05) increased following both resistance exercise trials. Significant increases in PAC1, and CD62P; and significant reductions for CD42b and CD41a were detected following both REs (p < 0.05). However, changes in PAC1 and CD62P were significantly different between the two protocols (p < 0.05), with higher increases detected following CRE. Acute RE increases platelet indices and platelet activation; and that CRE results in higher platelet activation than TRE, probably due to exercise-induced increases in shear stress.

Intense interval exercise induces lactate accumulation and a greater suppression of acylated ghrelin compared with submaximal exercise in middle-aged adults.

Exercise in young adults (18-25 yr) suppresses appetite in a dose-response relationship with exercise intensity. Although several mechanisms have been proposed to explain this response, lactate is the most well established. To date, no study has investigated this specifically in middle-aged adults where the appetite response to a meal is different. To explore the effects of submaximal, near maximal, and supramaximal intensity exercise on appetite regulation in middle-aged adults. Nine participants (age: 45 ± 10 yr) completed four experimental sessions: 1) no-exercise control (CTRL); 2) moderate-intensity continuous training [MICT; 30 min, 65% maximal oxygen consumption (V̇o2max)]; 3) high-intensity interval training (HIIT; 10 × 1 min efforts, 90% heart rate maximum, 1 min recovery); and 4) sprint interval training (SIT; 8 × 15 s "all-out" efforts, 2 min recovery). Acylated ghrelin, active glucagon-like peptide-1 (GLP-1), active peptide tyrosine tyrosine (PYY), lactate, and subjective appetite perceptions were measured pre-exercise, 0-, 30-, and 90-min postexercise. Energy intake was recorded the day before and day of each session. Acylated ghrelin was suppressed (P < 0.001, [Formula: see text] = 0.474) by HIIT (0-min and 30-min postexercise; P < 0.091, d > 1.84) and SIT (0-min, 30-min, and 90-min postexercise; P < 0.037, d > 1.72) compared with CTRL, and SIT suppressed concentrations compared with MICT (0-min and 30-min postexercise; P < 0.91, d > 1.19). There were no effects of exercise on active PYY, active GLP-1, appetite perceptions, or free-living energy intake (P > 0.126, [Formula: see text] < 0.200). Intense interval exercise that generates lactate accumulation suppresses acylated ghrelin with little effect on anorexigenic hormones, overall appetite, or free-living energy intake.NEW & NOTEWORTHY We explored the effects of submaximal, near maximal, and supramaximal intensity exercise on appetite regulation in middle-aged adults. Our data support the intensity-dependent effect of exercise on acylated ghrelin suppression that is closely related to lactate accumulation, though there appears to be little effect on anorexigenic hormones [active peptide tyrosine tyrosine (PYY), active glucagon-like peptide-1 (GLP-1)], overall appetite, or free-living energy intake. These data support previous results in younger adults where lactate was implicated in the exercise-induced suppression of acylated ghrelin.

Intraocular pressure variation from ocular compression in low and high myopia

ABSTRACT Clinical relevance Change in intraocular pressure during acute ocular compression is related to aqueous humour dynamics. Monitoring intraocular pressure (IOP) change throughout ocular compression has potential to evaluate aqueous outflow facilities. Background Recent studies have monitored lamina cribrosa deformation using optical coherence tomography during ocular compression. IOP was measured only once immediately after ocular compression. This study aimed to evaluate IOP changes during and after ocular compression and compare the differences between low and high myopia. Methods Two groups of young, healthy adults were age-matched and underwent ocular compression. IOP was measured at baseline and monitored during a 2-min ocular compression followed by a 10-min recovery phase. Rebound tonometry was used and applied at 30-s intervals. Results Thirty low and 30 high myopes (60 right eyes) were included in the study. They had similar baseline IOP at 14.9 mmHg. IOP was elevated to 21.7 ± 3.8 mmHg and 22.3 ± 4.2 mmHg for the low and high myopic group, respectively (p = 0.877). Low myopes had faster IOP decay during ocular compression at −3.24 mmHg/min than high myopes at −2.58 mmHg/min (p = 0.0528). The IOP dropped below the baseline level after the release of the compressive force. Low myopes had IOP that returned to baseline levels faster (at 360 s) than high myopes (at 510 s). Conclusion Measuring IOP once immediately after ocular compression could under-estimate the effect of IOP elevation during ocular compression. Further studies are required regarding IOP changes from ocular compression in aqueous humour dynamics.

Effects of a Graphene Heating Device on Fatigue Recovery of Biceps Brachii.

Far-infrared (FIR) is considered to be an ideal method to promote fatigue recovery due to its high permeability and strong radiation. In this paper, we report a flexible and wearable graphene heating device to help fatigue recovery of human exercise by using its high FIR divergence property. This study compares two different fatigue recovery methods, graphene far-infrared heating device hot application and natural recovery, over a 20 min recovery time among the male colleges' exhaustion exercise. Experimental results show that the achieved graphene device holds excellent electro-thermal radiation conversion efficiency of 70% and normal total emissivity of 89%. Moreover, the graphene FIR therapy in our work is more energy-efficient, easy to use, and wearable than traditional fatigue recovery methods. Such an anti-fatigue strategy offers new opportunities for enlarging potential applications of graphene film in body science, athletic training recovery, and wearable devices.

Performance changes during repeated military occupational test and its associations to physical performance

ABSTRACT The present study investigated performance changes during three runs (1 min recovery) of repeated military simulation task test (RMST) and its associations with physical performance. Voluntary male soldiers (N = 114) participated in a series of measurements of physical performance. Lower body explosive force production, anaerobic endurance and upper body strength endurance together explained 58% of the variance in the first RSMT (p < 0.001). The same variables explained the variance in the second and third runs of RSMT by 60% and 51%, but explosive force production was replaced with aerobic endurance, assessed by the 3.2 km loaded run (p < 0.001). This study demonstrated that the role of explosive power of the lower body decreased and military specific aerobic endurance increased when occupational performance was assessed under acute fatigue even during a short high-intensity test. These results may benefit tactical strength and conditioning coaches in training optimization for improved occupational performance in military.

Cognitive Function in Response to an Acute, High Intensity Exercise-Does Gender Plays a Role?

The growing evidence favoring the positive effect of exercise on cognition is mostly based on men participants (75%). We therefore exposed females and males to acute exercise and evaluated gender cognitive response to this intervention. Thirty- two adults (M=17; F=15) ages 18-34 participated in the study. The exercise consisted of ten repetitions: 10 seconds sprints at maximal speed, followed by 50 seconds active recovery. Stroop test (ST) 1-3; Trail-making test (TMT) 1-2; Word fluency were evaluated prior to; immediately post exercise; and at 45’ recovery. Two-way ANOVA with repeated measures (three test points X 2 gender groups) was used to test the effect of exercise on cognitive performance. All participants reached close to maximal heart rates at the end of the 10th sprint round. Stroop 1- 2 results improved for both males and females from pre to post exercise (p&lt;0.01). After 45’ males returned to pre-exercise while females retained high values. For Stroop 3 both genders improved from pre to post (p&lt;0.01) and retained high values after 45’. For TMT-1 males showed no response while females’ results improved immediately and at 45’ post intervention (p&lt;0.01). For TMT-2 both genders improved after exercise (p&lt;0.01); however, only females continued improving at 45’ recovery. Word fluency was positively affected by exercise in males only. Acute bout of exercise has a positive immediate effect on cognitive performance both in males and females; whereas males returned to pre-intervention values at 45’ min recovery, females retained the positive effect of exercise also after 45 minutes.

Effects of Acute Red Spinach Extract Ingestion on Repeated Sprint Performance in Division I NCAA Female Soccer Athletes

Red spinach extract is high in inorganic nitrate/nitrite (NO3/NO2) which has been shown to enhance vascular function, cognition, and physical performance. To date, there have been no investigations as to whether red spinach extract serves as an effective strategy to improve repeated exercise performance, which is applicable to many sports and activities. The purpose of this study was to investigate the effect of acute red spinach extract ingestion on repeated sprint ability in female athletes. Eleven Division I NCAA female athletes (ages 18–24) were recruited. In a double-blinded, randomized, counterbalanced design, participants completed two separate visits each with a different treatment: placebo (placebo; tomato juice) or red spinach extract (~400 mg nitrate). For each trial, participants consumed their respective treatment two hours before exercise. Following a warm-up, participants completed 3 × 15 s Wingate Anaerobic Tests (WAnTs) separated by 2 min of recovery. A capillary blood sample was obtained pre-exercise to measure NO2 concentrations. Performance outcomes, heart rate (heart rate), and rate of perceived exertion were measured following each WAnT. Blood lactate (La-) was obtained prior to exercise (PRE) and after the completion of the repeated sprints (POST). Each visit was separated by a minimal recovery period of 72 h. Mean power (p = 0.204), peak power (p = 0.067), heart rate (p = 0.151), and rate of perceived exertion (p = 0.379) were not significantly different between treatments. POST La- concentration was significantly higher with red spinach extract when compared to the placebo (p = 0.030). Furthermore, the fatigue index (p = 0.018) was significantly lower with red spinach extract. The results do not support the use of red spinach extract for the enhancement of power output during repeated anaerobic exercise. However, it may result in improved La-/H+ removal from the muscle, thereby combating physical fatigue.

Early Heart Rate Recovery after a 6-min Walking Test Predicts Clinical Benefits in Patients after Percutaneous Aortic Valve Implantation.

It was hypothesized that the time-appropriate return to a resting heart rate (HR) after cessation of exercise could be a marker for predicting outcomes in patients with heart failure (HF). We aimed to evaluate the prognostic value of HR recovery in functional improvement among adults with severe aortic stenosis undergoing percutaneous aortic valve implantation (TAVI). We performed a 6 min walk test (6MWT) in 93 individuals before TAVI and 3 months after the procedure. The change in walking distance was calculated. During the pre-TAVI 6MWT, we analyzed the differences between baseline HR, HR at the end of the test, and HR at the 1st, 2nd, and 3rd minute of recovery. After 3 months, 6MWT distances improved by 39 ± 63 m and reached a total of 322 ± 117 m. Multiple linear regression proved the differences between HR after 2 min of recovery and baseline HR in pre-TAVI after a 6MWT was the only significant predictor of waking distance improvement during follow-up. Our study suggests that analysis of HR recovery after a 6MWT may be a helpful and easy parameter to assess improvements in exercise capacity after TAVI. This simple method can help to identify patients in whom no significant benefit in functional improvement can be expected despite successful valve implantation.

First Principles Study of Toxic Gas Molecules Adsorption on Group IVA (C, Si, Ge) 2-Dimensional Materials

Two-dimensional materials from group IVA namely graphene, silicene, and germanene have gained research interest in various fields of applications recently due to their extraordinary properties. These substrates have been successfully synthesized and are found to have interesting gas sensing capabilities. In this work, first-principles study using density functional theory is carried out to investigate the adsorption of toxic gases such as CO, Cl2, NO2, and COCl2 on these monolayers. We analyze the best adsorption site and orientation for these molecules on the monolayers by calculating the adsorption energy. Charge transfer, the density of state (DOS) and band diagram calculations are performed to explore the changes in their electronic and structural properties due to the adsorbed gas molecules. As for the sensing performance, crude estimations of the sensitivity and recovery time are performed. The results show that silicene and germanene monolayers are better at detecting CO and NO2 as compared to graphene. They have a short recovery time for CO but a long recovery time for NO2 implying that they are better for scavenging NO2. Besides, silicene is also a better gas sensor for chlorine gas with a 44 min recovery time. As for graphene, it is the best gas sensor for phosgene among the substrates. This study gives a clear prediction of substrates for the detection of these toxic gases.

Human skeletal muscle mitochondrial responses to single-leg intermittent or continuous cycle exercise training matched for absolute intensity and total work.

There is renewed interest in the potential for interval (INT) training to increase skeletal muscle mitochondrial content including whether the response differs from continuous (CONT) training. Comparisons of INT and CONT exercise are impacted by the manner in which protocols are "matched", particularly with respect to exercise intensity, as well as inter-individual differences in training responses. We employed single-leg cycling to facilitate a within-participant design and test the hypothesis that short-term INT training would elicit a greater increase in mitochondrial content than work- and intensity-matched CONT training. Ten young healthy adults (five males and five females) completed 12 training sessions over 4 weeks with each leg. Legs were randomly assigned to complete either 30 min of CONT exercise at a challenging sustainable workload (~50% single-leg peak power output; Wpeak) or INT exercise that involved 10 × 3-min bouts at the same absolute workload. INT bouts were interspersed with 1min of recovery at 10% Wpeak and each CONT session ended with 10min at 10% Wpeak. Absolute and mean intensity, total training time, and volume were thus matched between legs but the pattern of exercise differed. Contrary to our hypothesis, biomarkers of mitochondrial content including citrate synthase maximal activity, mitochondrial protein content and subsarcolemmal mitochondrial volume increased after CONT (p < 0.05) but not INT training. Both training modes increased single-leg Wpeak (p < 0.01) and time to exhaustion at 70% of single-leg Wpeak (p < 0.01). In a work- and intensity-matched comparison, short-term CONT training increased skeletal muscle mitochondrial content whereas INT training did not.

Cardio-respiratory interactions in response to lower-body negative pressure

The relationship between heart rate and blood pressure, as well as cardiorespiratory coupling, play a critical role in maintaining blood pressure and organ perfusion during conditions of blood loss. Traditional vital signs such as blood pressure, breathing rate, and oxygen saturation are poor markers of blood loss, making it difficult for medics to assess the severity of central hypovolemia. Monitoring hemorrhage is further complicated by the fact that some patients have a low tolerance to hemorrhage and would reach the point of cardiovascular collapse in less time than high tolerant individuals. Therefore, this study aimed to investigate the potential of the physiological interaction between heart rate and blood pressure, and cardiorespiratory coupling to track the progression of simulated hemorrhage, as well as distinguish individuals with low tolerance (LT) from the ones with high tolerance (HT) to hypovolemia. Nineteen subjects (age: 28 ± 6 years; height: 170 ± 7 cm; weight: 68 ± 10 kg) underwent a progressive lower body negative pressure (LBNP) protocol in which the participant was supine inside the chamber for 12 min (baseline) before 12 min of chamber decompression at –20, –30, –40, –50 and –60 mmHg followed by a 12 min recovery period. Twelve subjects reached presyncope before or during –60 mmHg LBNP stage and were considered low tolerant (LT, 12 participants), while the ones who completed –60 mmHg were considered high tolerant (HT, 7 participants). Continuous blood pressure (BP), respiration (RSP), and electrocardiogram (ECG) signals were acquired simultaneously during baseline and each LBNP stage. RR interval was calculated using ECG, while systolic blood pressure (SBP), and pulse pressure were derived from BP waveform. Wavelet transform coherence and convergent cross-mapping techniques were employed to study the physiological interdependence and the causal relationship between heart rate, blood pressure, and respiration. The interaction between blood pressure and heart rate in terms of gain, active gain, and fraction time active to maintain homeostasis was higher in the LT group during baseline, and LBNP simulated mild, moderate, and severe hemorrhage. The significant time of interaction between SBP and RSP, and the causal effect of blood pressure on respiration were higher in the HT group during baseline compared to the LT group. HT participants also had a higher causal effect of respiration on blood pressure during –30 and –40 mmHg compared to LT. Moreover, the HT group displayed a higher causal drive of respiratory-related changes in heart rate and heart rate mediated changes in respiration during severe simulated hemorrhage (–40 mmHg) compared to the LT group. The calculated metrics to distinguish between individual LT from HT subjects achieved a sensitivity of 58%–83%, an accuracy of 63%–84%, and an area under the ROC curve of 74%–86%, while the overlap of LT individual responses with HT was 0%–33%. These results indicate the potential of cardiorespiratory coupling, and heart rate and blood pressure interaction toward tracking the progression of hemorrhage and distinguishing individuals with low tolerance to hypovolemia from those with high tolerance. Measurements of such interactions could improve clinical outcomes for patients with low tolerance to hypovolemia and therefore reduce morbidity and mortality through early implementation of life-saving interventions.

Comet assay in Aegla platensis (Decapoda: Anomura) using a non-lethal hemolymph field sampling for in situ monitoring of freshwater genotoxicity.

This study aimed to apply the comet assay on Aegla platensis crabs as a suitable non-destructive approach for in situ monitoring of freshwater genotoxicity. Animals were captured during four sampling periods in a stream under minor anthropogenic impacts in Southern Brazil. Crabs were captured with a hand net, then the hemolymph samples were collected, and the animals were released into the stream after a 20-min recovery time. Hemolymph samples were transported to the laboratory and used to perform the alkaline comet assay. Results showed an intermediate level in the DNA damage index (range 107.3-165.0 arbitrary unit). No significant differences were observed among the different sampling periods. Hemolymph was successfully used as a non-lethal source of biological samples, and the comet assay using A. platensis proved to be a feasible approach for genotoxicity studies.

Cardiac Behavior and Heart Rate Variability in Elderly Hypertensive Individuals during Aerobic Exercise: A Non-Randomized Controlled Study.

High blood pressure is an important public health problem due to its high prevalence, the difficulty to control it, and its high contribution to morbidity. A series of changes may be linked to the aging process, compromising cardiac conduction, and reducing cardiovascular baroreceptor function. Advancing age promotes a decline in heart rate variability and this decrease can increase the probability of cardiovascular disease. The aim of this study was to analyze the autonomic modulation of heart rate in hypertensive elderly individuals during and after a session of aerobic exercise, and to compare it with elderly individuals without cardiovascular or metabolic disease. Our study was a non-randomized controlled study with hypertensive elderly (HBP group) and elderly without cardiovascular and/or metabolic diseases (control group). Data on blood pressure and heart rate variability (HRV) were collected before, during, and after 30 min of aerobic physical exercise on a treadmill. There was a reduction in HF (ms2) and SD1 (ms) in the 5 min of recovery for the elderly in the control group. The elderly in the control group also had greater RMSSD and SD1 30 min post-exercise when compared to the initial mins of recovery. We concluded that there was no difference in autonomic modulation and global heart rate variability between elderly individuals without cardiovascular and metabolic diseases and hypertensive individuals after a bout of aerobic exercise. Elderly individuals without metabolic diseases showed a decrease in parasympathetic modulation and global variability between the time of rest and 5 min of recovery. However, up to 30 min of post-exercise recovery, they restored parasympathetic activity.