Acute Physiological Responses Research Articles

Postprandial appetite responses to a pecan enriched meal: A randomized crossover trial

Longer-term pecan consumption has shown appetite-regulating effects as a part of a free-living diet, yet the physiologic appetite responses to a single pecan-containing meal are unclear. The purpose of this study was to compare the acute physiologic, subjective, and direct appetite responses of a pecan-containing meal to an energy- and macronutrient-matched control meal. This was an acute meal challenge study utilizing a double-blinded randomized crossover design with two periods. Participants were young, healthy adults (BMI: 22.9 ± 3.3 kg/m2, age: 22 ± 3 y) who consumed a meal containing either 68 g of pecans (PEC; 795 kcal) or an energy- and macronutrient-matched control meal (CON; 794 kcal) on separate testing days. At both testing visits, five postprandial blood draws, and visual analog scale (VAS) questionnaires (in-lab) were used to determine differences in peptide YY (PYY), ghrelin, and subjective appetite over a 4-h postprandial period. Participants also completed VAS questionnaires (at-home) and food records for the rest of the day after leaving the testing visits. Thirty-one out of thirty-two randomized participants completed the study. There was a greater overall postprandial PYY response (p < 0.001), and a greater suppression of postprandial ghrelin after time point 120 min (p < 0.001), with the PEC vs. CON meal. Further, there was a greater increase in subjective fullness (p = 0.001), and suppression of at-home overall appetite (p = 0.02), from time 240–780 min post-meal with PEC vs. CON meals. There were no differences in self-reported EI between meals or any other VAS measure. In conclusion, a pecan-containing breakfast shake produced more favorable physiologic and subjective improvements in appetite compared to an energy- and macronutrient-matched control meal. This trial is registered at clinicaltrials.gov (NCT05230212).

Salivary uric acid dynamics are associated with stress response hormones among African American in an urban sample

Acute physiological responses to psychosocial stressors are a potential pathway underlying racial disparities in stress-related illnesses. Uric acid (UA) is a potent antioxidant that has been linked to disparities in stress-related illnesses, and recent research has shown that UA is responsive to acute social stress. However, an examination of the relationships between the purinergic system and other commonly measured stress systems is lacking. Here, we measure and characterize associations of salivary uric acid (sUA) with markers of hypothalamic-pituitary-adrenal (HPA) axis activation, sympathetic-adreno-medullar (SAM) axis activation, and acute inflammation. A community sample of 103 African Americans (33 male, 70 female) completed the Trier Social Stress Test to induce social-evaluative threat. Passive drool collected before, during, and after the stressor task provided salivary reactivity measures of UA (sUA), cortisol, dehydroepiandrosterone sulfate (DHEAS), salivary alpha amylase (sAA – a surrogate marker of SAM activity) and C-reactive protein (sCRP). Multiple regressions revealed that total activation of cortisol, DHEAS, and sCRP were each positively associated with higher total activation of sUA. Additionally, DHEAS reactivity was positively associated with sUA reactivity. Relationships between HPA-axis markers and sUA were especially observed among younger and male participants. Overall, findings suggest potential coordination of stress systems with sUA in response to acute stress, which may further the contributions of biological stress processes to racial health disparities.

ACUTE EFFECT OF INTERVAL TRAINING SET STRUCTURE ON PHYSIOLOGICAL AND PERCEPTUAL RESPONSES TO EXERCISE

INTRODUCTION &amp; AIMS A novel method for prescribing maximal aerobic speed (MAS) interval sessions involves the use of rest redistribution (RR). This approach could reduce perceived exertion and fatigue, preventing a decline in performance. This study aimed to compare acute physiological and perceptual responses between traditional (TS) and RR MAS interval training in endurance athletes. METHODS Twenty-five endurance runners (19 males, 6 females; age=31.9±8.5 y; maximal oxygen consumption (V̇O2max)=54.6±5.7 ml·kg·min-1; height=1.77±0.10 m; body-mass=74.0±13.0 kg) who ran &amp;gt;5 hours/week participated. Participants completed two MAS interval sessions equal in duration (18 min total, 360 s exercise, TS=660 s rest/RR=680 s rest) in a randomised order; TS: 3 sets x 6 repetitions (1 rep=20 s running:20 s rest) at 110% MAS and RR: 18 sets x 1 repetition (20 s running:40 s rest) at 110% MAS. During both sessions V̇O2 and heart rate (HR) were measured after each repetition, and blood lactate (HLa-) measured pre-exercise and after repetitions 6, 12 and 18. Rating of perceived exertion (RPE) was measured after repetitions 6, 12, and 18, and overall session RPE 10 minutes post-session. RESULTS Linear mixed effects models showed that TS led to a faster increase in V̇O2 (β=.16, p=.04) and HLa- (β=.09, p&amp;lt;.01), with consistently higher HR than RR (β=5.35, p&amp;lt;.01). Additionally, RPE (β=1.35, p&amp;lt;.01) and session RPE were lower in RR than TS (β=1.13, p&amp;lt;.01). CONCLUSION Results indicate that when session time is similar, TS (1:1 work-to-rest ratio), produces a greater physiological stimulus with higher V̇O2, HR and HLa-. Conversely, RR (1:2 work-to-rest ratio) resulted in lower perceived exertion and metabolic stress. This makes RR an appropriate choice for training periods with lower physiological stress or during periods of fatigue management. The reduced physiological demands in RR can facilitate a more controlled and sustainable training experience while still providing valuable training benefits.

Comparison of Acute Physiological Responses to Different Passive Heating Modalities

The repeated use of passive heating has gained popularity as a therapeutic approach toward promoting health and wellness. Passive heating elicits a rise in core body temperature and subsequent cardiovascular demand that can result in physiological adaptations beneficial to health. Hot water immersion, traditional sauna, and far-infrared sauna are three common modalities of passive heating; however, current literature lacks a direct comparison between these modalities. The purpose of this study is to characterize and compare the acute thermoregulatory and cardiovascular responses to a single bout of hot water immersion (HWI), traditional sauna (TRAD), and far-infrared sauna (FIR). We hypothesized that HWI will induce more pronounced thermoregulatory and cardiovascular responses when compared to both TRAD and FIR. In a randomized cross-over study design, nineteen healthy adults (9 F; age 24±4 years; body mass index 26.47±5 kg/m2) completed three bouts of acute passive heating: HWI (45 minutes at 40°C), TRAD (3x10 minutes at 80°C, separated by 5 min of thermoneutral rest), and FIR (45 minutes at 45-65°C) separated by at least 1 week. These temperatures and durations were chosen based on previous research and reflect typical use of these modalities. Measurements of arterial pressure, core temperature (Tc), and heart rate (HR) were collected at pre-heating baseline and at 5-min intervals during passive heating. Cardiac output (Q) was measured before, halfway, and at the end of heating using the open-circuit acetylene wash-in method. Mean arterial pressure (MAP) was calculated as 1/3 systolic + 2/3 diastolic and stroke volume (SV) and systemic vascular resistance (SVR) were calculated by Q/HR and MAP/Q. Data were analyzed using one-way ANOVAs to compare the changes from baseline to end of heating and are presented as mean with 95% confidence intervals. The change in Tc from baseline to end of heating was greater in HWI [+1.1°C (1.0, 1.3)] vs TRAD [+0.4°C (0.2, 0.6), p&lt;0.0001], HWI vs FIR [+0.1°C (-0.1,0.2), P &lt;0.0001], and TRAD vs FIR (P=0.0291). The increase in HR was greater in HWI [+39 bpm (35, 43)] vs. FIR [+26 bpm (21, 32), P=0.0017], with no differences in HWI vs. TRAD [+34 bpm (28, 40), P=0.4247] or TRAD vs. FIR (P=0.0793). Cardiac output increased to a greater extent in HWI [+3.9 L (3.3, 4.4)] vs. TRAD [+2.4 L (1.8, 2.9), P=0.0003)] and HWI vs. FIR [+1.7 L (1.2, 2.1), p&lt;0.0001], with no difference between TRAD vs FIR (P=0.1379). MAP decreased in HWI [-14 mmHg (-20, -9)] vs TRAD [-3 mmHg (-8, 1), P=0.0058] and HWI vs FIR [-0.5 mmHg (-5, 4), P=0.0003], with no difference between TRAD vs FIR (P= 0.7506). Conclusion: A single bout of HWI elicits the greatest thermoregulatory challenge and cardiovascular strain compared to both TRAD and FIR. Funded by American Heart Association (19TPA34890033) and NIH (R01HL144128). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Acute physiological and psychological responses during an incremental treadmill test wearing a new upper-body sports garment with elastomeric technology.

Background: The use of elastomeric technology in sports garments is increasing in popularity; however, its specific impact on physiological and psychological variables is not fully understood. Thus, we aimed to analyze the physiological (muscle activation of the pectoralis major, triceps brachii, anterior deltoid, and rectus abdominis, capillary blood lactate, systolic and diastolic blood pressure, and heart rate) and psychological (global and respiratory rating of perceived exertion [RPE]) responses during an incremental treadmill test wearing a new sports garment for the upper body that incorporates elastomeric technology or a placebo garment. Methods: Eighteen physically active young adults participated in two randomized sessions, one wearing the elastomeric garment and the other wearing a placebo. Participants performed in both sessions the same treadmill incremental test (i.e., starting at 8km/h, an increase of 2km/h each stage, stage duration of 3min, and inclination of 1%; the test ended after completing the 18km/h Stage or participant volitional exhaustion). The dependent variables were assessed before, during, and/or after the test. Nonparametric tests evaluated differences. Results: The elastomeric garment led to a greater muscle activation (p < 0.05) in the pectoralis major at 16km/h (+33.35%, p = 0.01, d = 0.47) and 18km/h (+32.09%, p = 0.02, d = 0.55) and in the triceps brachii at 10km/h (+20.28%, p = 0.01, d = 0.41) and 12km/h (+34.95%, p = 0.04, d = 0.28). Additionally, lower lactate was observed at the end of the test (-7.81%, p = 0.01, d = 0.68) and after 5min of recovery (-13.71%, p < 0.001, d = 1.00) with the elastomeric garment. Nonsignificant differences between the garments were encountered in the time to exhaustion, cardiovascular responses, or ratings of perceived exertion. Conclusion: These findings suggest that elastomeric garments enhance physiological responses (muscle activation and blood lactate) during an incremental treadmill test without impairing physical performance or effort perception.

Acute physiological, biomechanical, and perceptual responses of runners wearing downward-curved carbon fiber insoles.

In a randomized controlled cross-over study ten male runners (26.7 ± 4.9 years; recent 5-km time: 18:37 ± 1:07 min:s) performed an incremental treadmill test (ITT) and a 3-km time trial (3-km TT) on a treadmill while wearing either carbon fiber insoles with downwards curvature or insoles made of butyl rubber (control condition) in light road racing shoes (Saucony Fastwitch 9). Oxygen uptake, respiratory exchange ratio, heart rate, blood lactate concentration, stride frequency, stride length and time to exhaustion were assessed during ITT. After ITT, all runners rated their perceived exertion, perceived shoe comfort and perceived shoe performance. Running time, heart rate, blood lactate levels, stride frequency and stride length were recorded during, and shoe comfort and shoe performance after, the 3-km TT. All parameters obtained during or after the ITT did not differ between the two conditions [range: p = 0.188 to 0.948 (alpha value: 0.05); Cohen's d = 0.021 to 0.479] despite the rating of shoe comfort showing better scores for the control insoles (p = 0.001; d = -1.646). All parameters during and after the 3-km TT showed no differences (p = 0.200 to 1.000; d = 0.000 to 0.501) between both conditions except for shoe comfort showing better scores for control insoles (p = 0.017; d = -0.919). Running with carbon fiber insoles with downwards curvature did not change running performance or any submaximal or maximal physiological or biomechanical parameter and perceived exertion compared to control condition. Shoe comfort is impaired while running with carbon fiber insoles. Wearing carbon fiber insoles with downwards curvature during treadmill running is not beneficial when compared to running with control insoles.

Response of antioxidation and immunity to combined influences of pH and ammonia nitrogen in the spotted babylon (Babylonia areolata)

Spotted babylon were exposed to three different pH levels (7.0, 8.0 and 9.0) and four different concentrations of ammonia nitrogen (0.02, 1.02, 5.10 and 10.20 mg/L) in seawater to determine their acute toxicity and physiological responses to environmental fluctuation. The study evaluated four antioxidant enzymes: catalase (CAT), alkaline, superoxide dismutase (SOD), peroxidase (POD) and glutathione peroxidase (GSH-PX), and two immunoenzymes: acid phosphatase (ACP) and phosphatase (AKP). Over time, the immunoenzyme activity was significantly affected by pH and ammonia nitrogen concentration. After being exposed to pH and ammonia nitrogen, the spotted babylon showed signs of unresponsiveness to external stimuli, reduced vitality, slow movement, and an inability to maintain an upright position. Over time, the spotted babylon exhibited a trend of increasing and then decreasing GSH-PX, CAT, and SOD activities to adapt to the changing environment and enhance its immunity. On the contrary, the POD and ACP activities exhibited a decreasing trend initially, followed by an increasing trend over time and the AKP activity showed a gradual increase with time. The combined effect of pH and ammonia was found to be stronger than the effect of either factor alone. The interaction between pH and ammonia increased the activity of the spotted babylon antioxidant enzymes, induced oxidative stress, and reduced the ability of the spotted babylon's non-specific immune system to reverse it. Thus, the reverse-back of the spotted babylon was higher when pH and ammonia stress were dual than when pH or ammonia were single-factor stresses. The study results will establish a theoretical basis for analyzing the risk of multiple factors to the spotted babylon, and also enrich the basic information about the shellfish immune system.

Acute physiological responses and muscle recovery in females: a randomised controlled trial of muscle damaging exercise in hypoxia

BackgroundStudies have investigated the effects of training under hypoxia (HYP) after several weeks in a male population. However, there is still a lack of knowledge on the acute hypoxic effects on physiology and muscle recovery in a female population.MethodsThis randomized-controlled trial aimed to investigate the acute effects of muscle damaging exercise, performed in HYP and normoxia (CON), on physiological responses and recovery characteristics in healthy females. Key inclusion criteria were recreationally active female participants between the age of 18 to 35 years without any previous surgeries and injuries, whilst key exclusion criteria were acute pain situations, pregnancy, and medication intake. The females conducted a muscle-damaging protocol, comprising 5 × 20 drop-jumps, in either HYP (FiO2: 12%) or CON (FiO2: 21%). Physiological responses, including capillary oxygenation (SpO2), muscle oxygenation (SmO2), heart rate (HR), core- (Tcore) and skin- (Tskin) temperature were assessed at the end of each exercise set. Recovery characteristics were quantified by taking venous blood samples (serum creatine-kinase [CK], C-reactive protein [CRP] and blood sedimentation rate [BSR]), assessing muscle swelling of the quadriceps femoris muscle, maximum voluntary isometric contraction (MVIC) of the knee extensor muscles, countermovement jump (CMJ) performance and muscle soreness ratings (DOMS) at 24-, 48- and 72-hrs post-exercise.ResultsSpO2 (HYP: 76.7 ± 3.8%, CON: 95.5 ± 1.7%, p < 0.001) and SmO2 (HYP: 60.0 ± 9.3, CON: 73.4 ± 5.8%, p = 0.03) values were lower (p < 0.05) in HYP compared to CON at the end of the exercise-protocol. No physiological differences between HYP and CON were observed for HR, Tcore, and Tskin (all p > 0.05). There were also no differences detected for any recovery variable (CK, CRP, BSR, MVIC, CMJ, and DOMS) during the 72-hrs follow-up period between HYP and CON (all p > 0.05).ConclusionIn conclusion, our results showed that muscle damaging exercise under HYP leads to reduced capillary and muscle oxygenation levels compared to normoxia with no difference in inflammatory response and muscle recovery during 72 h post-exercise.Trial registrationNCT04902924, May 26th 2021.

Parametric analysis of an integrated cardio-respiratory model in preterm newborns during apnea

The analysis of the complex interactions involved in the acute physiological response to apnea-bradycardia events in preterm newborns remains a challenging task. This paper presents a novel integrated model of cardio-respiratory interactions, adapted to preterm newborns. A sensitivity analysis, based Morris’ screening method, was applied to study the effects of physiological parameters on heart rate and desaturation, during the simulation of a 15-seconds apnea-bradycardia episode. The most sensitive parameters are associated with fundamental, integrative physiological mechanisms involving: (i) respiratory mechanics (intermediate airways and lung compliance), (ii) fraction of inspired oxygen, (iii) metabolic rates (oxygen consumption rate), (iv) heart rate regulation and (v) chemoreflex (gain). Results highlight the relevant influence of physiological variables, involved in preterm apnea-bradycardia events.

Physiological Responses and Performance during an Integrated High-Intensity Interval Aerobic and Power Training Protocol.

This study compared the acute physiological responses and performance changes during an integrated high-intensity interval aerobic and power protocol. Sixteen moderately trained athletes (age: 20.1 ± 2.2 years, body height: 180.0 ± 6.5 cm, body mass: 75.7 ± 6.4 kg, VO2max: 55.8 ± 4.3 mL/kg/min) performed a 2 × 6 min interval training protocol with 2 min passive recovery between sets on two different occasions in random and counterbalanced order. Each 6 min set included repeated periods of 15 s exercise interspersed with 15 s passive rest. On one occasion (RUN), all exercise periods included running at 100% of maximal aerobic speed, while on the other occasion an integrated protocol was used (INT) in which each of the two 6 min sets included 4 × 1.5 min periods of running exercise at 100% of maximal aerobic speed in combination with jumping (i.e., 2 × 15 running with 15 s rest and 1 × 15 s drop jumping with 15 s rest). Time spent above 85% HRmax was two-fold higher in INT compared to RUN (8.5 ± 3.6 vs. 4.3 ± 3.9 min, respectively, p = 0.0014). Interestingly, heart rate increased above 95% HRmax only in INT and almost no time was spent above 95% HRmax in RUN (1.4 ± 1.9 vs. 0.1 ± 0.2 min, respectively, p = 0.008). Blood lactate concentration at the end of the second set of INT was higher than RUN (7.3 ± 3.2 vs. 4.6 ± 2.7 mmol/L, p = 0.002). Countermovement jump was higher in INT after the end of second set by 6.4% (p = 0.04), 6.7% (p = 0.04), 7.8% (p < 0.01) and 7.3% (p < 0.001), at 2, 6 and 8 min after set 2. In conclusion, the comparison between INT and RUN shows that INT not only elicits higher physiological and metabolic responses, but also acutely enhances neuromuscular performance for at least 8 min after the end of exercise. The integrated running/jumping high-intensity interval exercise approach could be a very useful and time efficient method for strength and conditioning coaches, especially in team sports, in which the time available for the improvement of physical parameters is limited.

Effects of Acute Sleep Deprivation on the Physiological Response to Woodsmoke and Exercise.

To evaluate sleep deprivation effects on the acute physiological response to a combined stressor of woodsmoke and exercise. Ten participants completed two exercise trials (8 hours of sleep vs 4 hours) with woodsmoke. Trials were conducted in a crossover design. Key measures examined before and after each trial included heart rate variability, pulse wave velocity, blood pressure, pulmonary function testing, and oxidative stress. Acute sleep deprivation experienced before exercise and woodsmoke exposure did not impact metrics of heart rate variability, pulse wave velocity, pulmonary function testing, blood pressure, or oxidative stress. Acute sleep deprivation did not amplify physiologic metrics in response to moderate-intensity aerobic exercise with inhaled woodsmoke. Although findings do not eliminate the negative impacts of inhaling woodsmoke, more research is needed to understand the acute effects of woodsmoke exposure on the cardiovascular system. 1.

Effect of hypoxic sprint interval exercise and normoxic recovery on performance and acute physiological responses

AbstractHypoxic exercise, which can induce arterial and tissue deoxygenation, promotes physiological adaptations. However, reduced oxygen availability can lower the absolute training intensity (i.e., mechanical stress). Adding normoxic recovery to sprint interval exercise (SIE) is one potential approach to strike a balance between providing a hypoxic stimulus and maintaining the absolute training intensity. However, the effects of adding normoxic recovery to SIE on performance and physiological responses are uncertain. We tested the hypothesis that hypoxic SIE with normoxic recovery enhances arterial deoxygenation and muscle deoxygenation levels without impeding performance compared to an entirely normoxic condition. On separate days, seven male sprinters performed 4 × 30‐s ‘all‐out’ cycle sprints with 4.5‐min recovery with hypoxic exposure (FiO2: 12.7%O2) applied continuously (hypoxia, HYP), intermittently during sprint periods only (intermittent, INT), or not at all (normoxia, NOR). Power output, oxygen saturation, muscle oxygenation, surface electromyography (EMG) activity, heart rate, blood lactate concentration, and ratings of perceived exertion were measured. The total work significantly decreased in HYP than NOR (p &lt; 0.05) and INT (p &lt; 0.01). The aTrterial oxygen saturation was lower during HYP than NOR (∼86% vs. ∼97%; p &lt; 0.001), while lower values were also obtained for INT than NOR during sprint periods (∼85% vs. ∼97%; p &lt; 0.001) but not during recovery periods (∼96% vs. ∼97%). The heart rate differed (p &lt; 0.05) between conditions (NOR: ∼164 bpm; INT: ∼160 bpm; HYP: ∼156 bpm). No other variables demonstrated significant differences between conditions. Adding hypoxia during exercise while recovering in normoxia did not compromise exercise capacity during SIE, despite inducing larger arterial deoxygenation levels compared to normoxia.

The acute physiological stress responses after total sleep deprivation in health individuals: a systematic review

The acute physiological stress responses after total sleep deprivation in health individuals: a systematic review

Toxicity of nitrophenolic pollutant 4-nitroguaiacol to terrestrial plants and comparison with its non-nitro analogue guaiacol (2-methoxyphenol)

Phenols, and especially their nitrated analogues, are ubiquitous pollutants and known carcinogens which have already been linked to forest decline. Although nitrophenols have been widely recognized as harmful to different aquatic and terrestrial organisms, we could not find any literature assessing their toxicity to terrestrial plants. Maize (monocot) and sunflower (dicot) were exposed to phenolic pollutants, guaiacol (GUA) and 4-nitroguaiacol (4NG), through a hydroponics system under controlled conditions in a growth chamber. Their acute physiological response was studied during a two-week root exposure to different concentrations of xenobiotics (0.1, 1.0, and 10 mM). The exposure visibly affected plant growth and the effect increased with increasing xenobiotic concentration. In general, 4NG affected plants more than GUA. Moreover, sunflower exhibited an adaptive response, especially to low and moderate GUA concentrations. The integrity of both plant species deteriorated during the exposure: biomass and photochemical pigment content were significantly reduced, which reflected in the poorer photochemical efficiency of photosystem II. Our results imply that 4NG is taken up by sunflower plants, where it could enter a lignin biosynthesis pathway.

Biomarker Responses to Acute Exercise and Relationship with Brain Blood Flow.

There is evidence that aerobic exercise is beneficial for brain health, but these effects are variable between individuals and the underlying mechanisms that modulate these benefits remain unclear. We sought to characterize the acute physiological response of bioenergetic and neurotrophic blood biomarkers to exercise in cognitively healthy older adults, as well as relationships with brain blood flow. We measured exercise-induced changes in lactate, which has been linked to brain blood flow, as well brain-derived neurotrophic factor (BDNF), a neurotrophin related to brain health. We further quantified changes in brain blood flow using arterial spin labeling. As expected, lactate and BDNF both changed with time post exercise. Intriguingly, there was a negative relationship between lactate response (area under the curve) and brain blood flow measured acutely following exercise. Finally, the BDNF response tracked strongly with change in platelet activation, providing evidence that platelet activation is an important mechanism for trophic-related exercise responses. Lactate and BDNF respond acutely to exercise, and the lactate response tracks with changes in brain blood flow. Further investigation into how these factors relate to brain health-related outcomes in exercise trials is warranted.

RESPOSTAS FISIOLÓGICAS AGUDAS À “HIPÓXIA INTERMITENTE DE RECUPERAÇÃO” NO HIIT

ABSTRACT Introduction: Traditional intermittent hypoxia training improves sport performance after short periods of exposure, but acute exposure to intermittent hypoxia leads to decreased training intensity and technical quality. The solution to overcome these negative effects may be to perform efforts in normoxia and the intervals between efforts in hypoxia, maintaining the quality of training and the benefits of hypoxia. Objective: This study aimed to evaluate the acute physiological responses to hypoxia exposure during recovery between high intensity efforts. Materials and methods: Randomized, one-blind, placebo-controlled study. Sixteen men performed a graded exercise test to determine their maximal intensity and two sessions of high-intensity interval training. The training intervals could be in hypoxia (HRT), FIO2: 0.136 or normoxia (NRT), FIO2: 0.209. During the two-minute interval between the ten one-minute efforts, peripheral oxygen saturation (SpO2), heart rate (HR), blood lactate ([La]), blood glucose ([Glu]) were constantly measured. Results: There were differences in HR (TRN = 120 ± 14 bpm; TRH = 129 ± 13 bpm, p &lt; 0.01) and SpO2 (TRN = 96.9 ± 1.0%; TRH = 86.2 ± 3.5%, p &lt; 0.01). No differences in [La] and [Glu] TRN (4.4 ± 1.7 mmol.l-1; 3.9 ± 0.5 mmol.l-1) and TRH (5.2 ± 2.0 mmol.l-1; 4.0 ± 0.8 mmol.l-1, p = 0.17). Conclusion: The possibility of including hypoxia only in the recovery intervals as an additional stimulus to the training, without decreasing the quality of the training, was evidenced. Level of Evidence II; Randomized Clinical Trial of Minor Quality.

Effect of a moderate alcohol dose on physiological responses during rest and prolonged cycling.

We examined the acute effects of a moderate alcohol dose (48g) ingested before prolonged cycling on acute physiological responses in eight healthy males (mean ± SD; 23 ± 2years; 1.77 ± 0.04m; 75.8 ± 4.1kg). In a randomized order, euhydrated participants completed two experimental sessions with the sequence of 150-min seated at rest, 90-min of cycling at 50% of the maximal rate of oxygen consumption ($\dot{\textrm V}\textrm O$2max), 120-min seated at rest. Participants drank 250mL of flavored squash with or without alcohol (vodka; ~16g) at 10, 40, and 70min of the initial resting phase, giving a cumulative fluid intake of 750mL with 48g of alcohol. Heart rate, blood glucose, breath alcohol concentration, and respiratory gasses were recorded throughout the entire trial with cumulative urine volume recorded during both rest phases. Total carbohydrate (control = 115 ± 19g: alcohol = 119 ± 21g; P= 0.303) and lipid (control = 17 ± 4g: alcohol = 20 ± 7g; P= 0.169) oxidation was similar between conditions. Average heart rate was 7% higher in the alcohol condition (control = 111 ± 12bpm; alcohol = 119 ± 11bpm; P= 0.003). Blood glucose concentrations were similar between conditions during (P= 0.782) and after exercise (P= 0.247). Urine output was initially increased between conditions following alcohol ingestion before diminishing (P< 0.001) with no difference in total cumulative urine output (P= 0.331). Consuming an alcoholic drink containing 48g of alcohol in the hour before moderate intensity sub-maximal aerobic exercise led to detectable increases in heart rate and rate of urine production with no effect on substrate use.

Acute Performance, Physiological and Perceptual Responses to Repeated-Sprint Exercise with Continuous or Intermittent Blood Flow Restriction

Acute Performance, Physiological and Perceptual Responses to Repeated-Sprint Exercise with Continuous or Intermittent Blood Flow Restriction

One Velocity Loss Threshold Does Not Fit All: Consideration of Sex, Training Status, History, and Personality Traits When Monitoring and Controlling Fatigue During Resistance Training

PurposeThis study aimed to quantify the potential variability in the volume of work completed after reaching different velocity loss (VL) thresholds and determine the effects of sex, training status and history, as well as psychological traits on the reliability and magnitude of the amount of work completed after reaching different VL thresholds using different loads in the back-squat exercise.MethodsForty-six resistance-trained people (15 females and 31 males; 18 to 40 years of age) with a wide range of strength levels, training experience, and different training practices were recruited and performed a one-repetition maximum (1RM) test, and two repetitions to failure (RTF) tests 72 h apart. RTF tests were performed with 70, 80, and 90% of 1RM with 10 min of rest between sets. The Bland–Altman analysis for multiple observations per participant and equivalence tests were used to quantify the variability in the volume of work completed after reaching different VL thresholds, whereas linear and generalised mixed-effects models were used to examine the effects of different moderators on the stability and magnitude of the amount of work completed after reaching different VL thresholds.ResultsThe findings of the present study question the utility of using VL thresholds to prescribe resistance training (RT) volume as the agreement in the amount of work completed across two consecutive testing sessions was not acceptable. Regardless of the load used, females completed more repetitions than males across VL thresholds, while males performed repetitions at higher velocities. In addition, individuals with higher levels of emotional stability also tended to perform more repetitions across VL thresholds. Finally, sex, choice of load, strength levels and training practices, as well as emotional stability affected the linearity of the repetition–velocity relationship and when sets terminated.ConclusionUsing the same VL thresholds for all individuals, while assuming generalisability of the stimuli applied, would likely lead to variable acute physiological responses to RT and divergent neuromuscular adaptations over long term. Therefore, VL monitoring practices could be improved by considering sex, training status, history, and psychological traits of individuals due to their effects on the variability in responses to different VL thresholds.

Acute Physiological and Perceptual Responses to Whole-Body High-Intensity Interval Training Compared with Equipment-Based Interval and Continuous Training.

Low-volume, time-efficient high-intensity interval training (HIIT), which involves whole-body (WB) callisthenics exercises, has gained worldwide popularity in recent years. However, the physiological and perceptual impact of WB-HIIT in comparison to specialised, equipment-based training is relatively less studied. This study compared the acute physiological and perceptual responses to a single session of WB-HIIT, ergometer-based HIIT (ERG-HIIT) and conventional moderate-intensity continuous training (MICT). Fourteen physically inactive adults (age: 28.4 ± 6.5 years, VO2peak: 31.0 ± 6.2 mL· kg-1· min-1) underwent three main trials (WB-HIIT: 12 x 30-s high-intensity callisthenics workout; ERG: HIIT: 12 x 30-s high-intensity cycling bouts; MICT: 30-min cycling at 50% peak power output) in a randomized cross-over order 3-7 days apart. The mean session heart rate (HR) and perceived exertion were comparable across all three protocols (p > 0.05). WB-HIIT attained a similar peak HR (87.4 ± 9.4 %HRmax) as that of ERG-HIIT (83.0 ± 8.6 %HRmax), and significantly greater than that of MICT (78.7 ± 5.5 %HRmax, p = 0.001). However, WB-HIIT induced significantly higher blood lactate levels (7.2 ± 1.8 mmol/L) compared to both ERG-HIIT (5.1 ± 1.3 mmol/L, p < 0.05) and MICT (3.1 ± 1.5 mmol/L, p < 0.001). The participants reported higher self-efficacy and greater enjoyment with WB-HIIT compared to MICT (p < 0.05). The mean HR and perceived exertion responses to WB-HIIT are comparable to those of equipment-based HIIT and MICT; however, WB-HIIT results in greater metabolic strain than both other modalities. Despite this, the overall perceptual responses to WB-HIIT are positive, suggesting that it could be a viable exercise alternative, especially for individuals with limited exercise time and restricted access to facilities and equipment.