Moderate-intensity Cycling Research Articles

The Effects of Exergame Telerehabilitation in Persons With Subjective Cognitive Decline.

The primary aim of this Stage IB randomized controlled trial (RCT) was to test the preliminary effects of a dual-task exergaming telerehabilitation intervention on cognition and aerobic fitness, compared to aerobic exercise (AEx) only and attention control (stretching) in older adults with subjective cognitive decline. This RCT randomized 39 participants on a 2:1:1 allocation ratio to supervised exergame (n = 20), AEx (n = 11), and stretching (n = 8) for 12 weeks. The dual-task exergaming was concurrent moderate-intensity cycling and BrainFitRx cognitive telerehabilitation. Cognition was assessed by NIH Toolbox Cognitive Battery and aerobic fitness by 6-minute walk test (6MWT) and shuttle walk test. The participants were 74.6 (7.4) years old and 69% were female. The effect of time was significant, F(1, 23.9) = 13.16, p = .001, for the Fluid Composite score, and significant within-group changes were seen for the exergame group, t(14.08) = 2.53, p = .024, d = 0.33. Between-group changes did not reach significant levels for any cognitive test. Between-group changes for the 6MWT were not significant. The exergame participants further improved their fluid cognition, whereas the AEx and stretching groups did not, indicating a potential synergistic effect from AEx and cognitive training. The aerobic fitness changes were similar between the exergame and AEx-only groups, indicating that the feasibility of adding cognitive training to AEx concurrently without sacrificing gains in aerobic fitness from AEx. This study shows the flexibility of exergame delivery and its potentially therapeutic effects in persons at risk for Alzheimer's dementia. NCT04311736.

Effect of acute moderate-intensity cycling on cfDNA levels considering menstrual cycle phases.

We aimed to determine the effects of exercise on cell-free DNA (cfDNA) levels and concentration changes during the menstrual cycle in participants with regular menstrual cycles and no exercise habits. Eleven sedentary female students with regular menstrual cycles and ovulation performed bicycle exercises at 60% VO2max for 30 min during the menstrual, ovulatory, and luteal phases. Blood samples were collected before (Pre), immediately after (Post 0), 30 min after (Post 30), and 60 min after (Post 60) exercise. Blood concentrations of ovarian hormones, cfDNA, prostaglandin F2a (PGF2α), interleukin-6 (IL-6), and aromatase were evaluated. Based on the concentration of ovarian hormones, seven individuals were finally analyzed. No significant phase difference was observed in cfDNA across all time points. cfDNA (menstrual phase: p = 0.028, ovulatory phase: p = 0.018, and luteal phase: p = 0.048) and aromatase concentrations (menstrual phase: p = 0.040, ovulatory phase: p = 0.039, and luteal phase: p = 0.045) significantly increased from Pre to Post 0 in all phases. Serum estradiol (E2) levels were significantly higher in the luteal phase at all time points than in the menstrual phase (Pre: p < 0.001, Post 0: p < 0.001, Post 30: p = 0.005, and Post 60: p = 0.011); however, serum progesterone (P4) levels were significantly higher in the luteal phase at all time points than in the menstrual (Pre: p < 0.001, Post 0: p < 0.001, Post 30: p < 0.001, and Post 60: p < 0.001) and ovulatory phases (Pre: p = 0.005, Post 0: p = 0.005, Post 30: p = 0.003, and Post 60: p = 0.003). E2 levels significantly increased from Pre to Post 0 in the ovulatory and luteal phases, whereas P4 levels increased in the luteal phase. Progesterone to estradiol level ratio (P4/E2) changes from Pre to Post 0 (%baseline) during the luteal phase were significantly negatively correlated (r = -0.82, p = 0.046) with the changes in cfDNA from Pre to Post 0. Furthermore, the repeated measures correlation between P4/E2 and cfDNA level showed a significant negative correlation in ovulatory and luteal phases. The results indicate that while resting cfDNA levels are unlikely to be affected by a woman's menstrual cycle, the increase in cfDNA after exercise is higher in the ovulatory phase (when only E2 increases) and lower in the luteal phase (when E2 and P4 increase with exercise) compared to that in the menstrual phase (when E2 and P4 are in low levels), suggesting the contribution of increased ovarian hormone levels after exercise.

The Effects of a 90-km Outdoor Cycling Ride on Performance Outcomes Derived From Ramp-Incremental and 3-Minute All-Out Tests.

Bitel, M, Keir, DA, Grossman, K, Barnes, M, Murias, JM, and Belfry, GR. The effects of a 90-km outdoor cycling ride on performance outcomes derived from ramp-incremental and 3-minute all-out tests. J Strength Cond Res 38(3): 540-548, 2024-The purpose of this study was to determine whether laboratory-derived exercise intensity and performance demarcations are altered after prolonged outdoor cycling. Male recreational cyclists ( n = 10; RIDE) performed an exhaustive ramp-incremental test (RAMP) and a 3-minute all-out test (3MT) on a cycle ergometer before and after a 90-km cycling ride. RAMP-derived maximal oxygen uptake (V̇O 2max ), gas exchange threshold (GET), respiratory compensation point (RCP), and associated power output (PO), as well as 3MT-derived critical power (CP) and work performed above CP, were compared before and after ∼3 hours of outdoor cycling. Six active men served as "no-exercise" healthy controls (CON), who, instead, rested for 3 hours between repeated RAMP and 3MT tests. During the 90-km ride, the duration within the moderate-intensity, heavy-intensity, and severe-intensity domains was 59 ± 24%, 40 ± 24%, and 1 ± 1%, respectively. Compared with pre-90 km, post-RAMP exhibited reductions in (a) V̇O 2max (4.04 ± 0.48 vs. 3.80 ± 0.38 L·min -1 ; p = 0.026) and associated PO (392 ± 30 W vs. 357 ± 26 W; p = 0.002); (b) the V̇O 2 and PO at RCP (3.49 ± 0.46 vs. 3.34 ± 0.43 L·min -1 ; p = 0.040 and 312 ± 40 W vs. 292 ± 24 W; p = 0.023); and (c) the PO (214 ± 32 W vs. 198 ± 25 W; p = 0.027), but not the V̇O 2 at GET (2.52 ± 0.44 vs. 2.44 ± 0.38 L·min -1 ; p = 0.388). Pre-90 km vs. post-90 km 3MT variables showed reduced W' (9.8 ± 3.4 vs. 6.8 ± 2.6 kJ; p = 0.002) and unchanged CP (304 ± 26 W and 297 ± 34 W; p = 0.275). In the CON group, there were no differences in V̇O 2max , GET, RCP, W', CP, or associated power outputs ( p > 0.05) pre-to-post 3 hours of rest. The preservation of critical power demonstrates that longer-duration maximal efforts may be sustained after long-duration cycle. However, shorter sprints and higher-intensity efforts eliciting V̇O 2max will exhibit decreased PO after 3 hours of a predominantly moderate-intensity cycle.

Evaluation of a wearable fabric-based sensor for accurate sodium determination in sweat during exercise.

Newly developed wearable fabric sensors (WFS) can increase the ease and accuracy of sweat sodium measurements by performing simultaneous sampling and analysis on the body during exercise. Determine the accuracy of a WFS for measurement of sodium concentration in sweat. Subjects wore a WFS prototype and sweat collectors on their forearm during cycle ergometry. Subjects exercised at a moderate intensity (~ 65% heart rate reserve) for 30-60min. Sweat samples were collected and analyzed using a commercial sweat sodium analyzer (SSA) every 10-15min. WFS were adhered with an armband and connected to custom built electronics. Accuracy was determined by comparing predicted WFS concentration to the actual concentration from the commercial SSA and analyzed statistically using ANOVA and Bland-Altman plots. A total of 19 subjects completed the study. The average sweat sodium concentration was 59mM ± 22mM from a SSA compared with 54mM ± 22mM from the WFS. Overall, the average accuracy of the WFS was 88% in comparison to the SSA with p = 0.45. A line of best fit comparing predicted versus actual sweat sodium concentration had a slope of 0.99, intercept of - 4.46, and an r2 of 0.90. Bland-Altman analysis showed the average concentration difference between the WFS and the SSA was 5.35mM, with 99% of data points between ± 1.96 times the standard deviation. The WFS accurately predicted sweat sodium concentration during moderate intensity cycle ergometry. With the need for precise assessment of sodium loss, especially during long duration exercise, this novel analysis method can benefit athletes and coaches. Further research involving longer duration and more intense exercise is warranted.

The effects of sleep deprivation, acute hypoxia, and exercise on cognitive performance: A multi-experiment combined stressors study

IntroductionBoth sleep deprivation and hypoxia have been shown to impair executive function. Conversely, moderate intensity exercise is known to improve executive function. In a multi-experiment study, we tested the hypotheses that moderate intensity exercise would ameliorate any decline in executive function after i) three consecutive nights of partial sleep deprivation (PSD) (Experiment 1) and ii) the isolated and combined effects of a single night of total sleep deprivation (TSD) and acute hypoxia (Experiment 2). MethodsUsing a rigorous randomised controlled crossover design, 12 healthy participants volunteered in each experiment (24 total, 5 females). In both experiments seven executive function tasks (2-choice reaction time, logical relations, manikin, mathematical processing, 1-back, 2-back, 3-back) were completed at rest and during 20 min semi-recumbent, moderate intensity cycling. Tasks were completed in the following conditions: before and after three consecutive nights of PSD and habitual sleep (Experiment 1) and in normoxia and acute hypoxia (FIO2 = 0.12) following one night of habitual sleep and one night of TSD (Experiment 2). ResultsAlthough the effects of three nights of PSD on executive functions were inconsistent, one night of TSD (regardless of hypoxic status) reduced executive functions. Significantly, regardless of sleep or hypoxic status, executive functions are improved during an acute bout of moderate intensity exercise. ConclusionThese novel data indicate that moderate intensity exercise improves executive function performance after both PSD and TSD, regardless of hypoxic status. The key determinants and/or mechanism(s) responsible for this improvement still need to be elucidated. Future work should seek to identify these mechanisms and translate these significant findings into occupational and skilled performance settings.

P096 The Effect of Moderate-Intensity Exercise on Sleep Quality and Quantity in Healthy Adult Males

Abstract Introduction Acute exercise may have the ability to disrupt sleep in healthy adults. Given the popularity of afternoon exercise, it is important to determine how this affects sleep. Therefore, the aim of this study was to investigate the effect of afternoon moderate-intensity cycling exercise on objective and subjective sleep in healthy adult males. Methods To assess the effect of moderate-intensity afternoon exercise on sleep quality and quantity, 12 healthy adult males who were identified as good sleepers completed a repeated-measures, counter-balanced, crossover study design with two conditions (moderate-intensity aerobic exercise or no exercise). The exercise task involved cycling for 40 minutes at 70%HRmax and was completed ~15:30h. Polysomnography was used to measure sleep during a 9-h sleep opportunity (23:00h to 08:00h). Results There were no statistically significant differences in objective or subjective sleep between conditions. Exercise had a medium-sized effect on reducing total sleep time (mean ± SD; control 493.71 ± 12.59 mins vs exercise: 471.46 ± 55.19 mins; Cohen’s d: 0.56), sleep efficiency (mean ± SD; control 91.43 ± 2.33 % vs exercise: 87.31 ± 10.22 %; Cohen’s d: 0.56), and increasing REM onset latency (mean ± SD; control: 76.13 ± 45.10 mins vs exercise: 102.75 ± 46.85 mins; r: -0.33) (all p &amp;gt; 0.05). Discussion Healthy adult males can complete afternoon moderate-intensity exercise without compromising subsequent sleep. Individual responses in objective sleep outcomes may vary after exercise.

Body mass and V'O2 at rest affect gross efficiency during moderate-intensity cycling in untrained young healthy men: correlations with V'O2MAX.

Seventeen young healthy physically active males (age 23 ±3 years; body mass (BM) 72.5 ±7.9 kg; height 178 ±4 cm, (mean ±SD)), not specifically trained in cycling, participated in this study. The subjects performed two cycling incremental tests at the pedalling rate of 60 rev x min-1. The first test, with the power output (PO) increases of 30 W every 3 min, was to determine the maximal oxygen uptake (V'O2max) and the power output (PO) at V'O2max, while the second test (series of 6 minutes bouts of increasing intensity) was to determine energy expenditure (EE (V'O2)), gross efficiency (GE (V'O2/PO)) and delta efficiency (DE(ΔV'O2/DPO)) during sub-lactate threshold (LT) PO. V'O2max was 3.79 ±0.40 L x min-1 and the PO at V'O2max was 288 ±27 W. In order to calculate GE and DE the V'O2 was expressed in W, by standard calculations. GE measured at 30 W, 60 W, 90 W and 120 W was 11.6 ±1.4%, 17.0 ±1.4%, 19.6 ±1.2% and 21.4 ±1.1%, respectively. DE was 29.8 ±1.9%. The subjects' BM (range 59-87 kg) was positively correlated with V'O2 at rest (p<0.01) and with the intercept of the linear V'O2 vs. PO relationship (p<0.01), whereas no correlation was found between BM and the slope of V'O2 vs. PO. No correlation was found between BM and DE, whereas GE was negatively correlated with BM (p<0.01). GE was also negatively correlated with V'O2max and the PO at V'O2max (p<0.01). We conclude that: V'O2 at rest affects GE during moderate-intensity cycling and GE negatively corelates with V'O2max and the PO at V'O2max in young healthy men.

The effects of postprandial exercise and meal glycemic index on plasma glucose and glucoregulatory hormone responses after Roux-en-Y gastric bypass.

Postprandial hypoglycemia is a complication of Roux-en-Y gastric bypass (RYGB), but the effects of postprandial exercise and meal glycemic index (GI) on postprandial glucose and glucoregulatory hormone responses are unknown. Ten RYGB-operated and 10 age and weight-matched unoperated women completed four test days in random order ingesting mixed meals with high GI (HGI, GI = 93) or low GI (LGI, GI = 54), but matched on energy and macronutrient content. Ten minutes after meal completion, participants rested or cycled for 30 min at 70% of maximum oxygen uptake (V̇o2max). Blood was collected for 4 h. Postprandial exercise did not lower plasma nadir glucose in RYGB after HGI (HGI/rest 3.7 ± 0.5 vs. HGI/Ex 4.1 ± 0.4 mmol/L, P = 0.070). Replacing HGI with LGI meals raised glucose nadir in RYGB (LGI/rest 4.1 ± 0.5 mmol/L, P = 0.034) and reduced glucose excursions (Δpeak-nadir) but less so in RYGB (-14% [95% CI: -27; -1]) compared with controls (-33% [-51; -14]). Insulin responses mirrored glucose concentrations. Glucagon-like peptide 1 (GLP-1) responses were greater in RYGB versus controls, and higher with HGI versus LGI. Glucose-dependent insulinotropic polypeptide (GIP) responses were greater after HGI versus LGI in both groups. Postexercise glucagon responses were lower in RYGB than controls, and noradrenaline responses tended to be lower in RYGB, whereas adrenaline responses were similar between groups. In conclusion, moderate intensity cycling shortly after meal intake did not increase the risk of postprandial hypoglycemia after RYGB. The low GI meal increased nadir glucose and reduced glucose excursions compared with the high GI meal. RYGB participants had lower postexercise glucagon responses compared with controls.NEW & NOTEWORTHY We investigate the effect of moderate exercise after a high or a low glycemic index meal on nadir glucose and glucoregulatory hormones in gastric bypass-operated individuals and in matched unoperated controls. Cycling shortly after meal intake did not increase the risk of hypoglycemia in operated individuals. The low glycemic index meal increased glucose nadir and reduced excursions compared with the high glycemic index meal. Operated individuals had lower postexercise glucagon responses compared with controls.

Moderate intensity aerobic exercise may enhance neuroplasticity of the contralesional hemisphere after stroke: a randomised controlled study

Upregulation of neuroplasticity might help maximize stroke recovery. One intervention that appears worthy of investigation is aerobic exercise. This study aimed to determine whether a single bout of moderate intensity aerobic exercise can enhance neuroplasticity in people with stroke. Participants were randomly assigned (1:1) to a 20-min moderate intensity exercise intervention or remained sedentary (control). Transcranial magnetic stimulation measured corticospinal excitability of the contralesional hemisphere by recording motor evoked potentials (MEPs). Intermittent Theta Burst Stimulation (iTBS) was used to repetitively activate synapses in the contralesional primary motor cortex, initiating the early stages of neuroplasticity and increasing excitability. It was surmised that if exercise increased neuroplasticity, there would be a greater facilitation of MEPs following iTBS. Thirty-three people with stroke participated in this study (aged 63.87 ± 10.30 years, 20 male, 6.13 ± 4.33 years since stroke). There was an interaction between Time*Group on MEP amplitudes (P = 0.009). Participants allocated to aerobic exercise had a stronger increase in MEP amplitude following iTBS. A non-significant trend indicated time since stroke might moderate this interaction (P = 0.055). Exploratory analysis suggested participants who were 2–7.5 years post stroke had a strong MEP facilitation following iTBS (P < 0.001). There was no effect of age, sex, resting motor threshold, self-reported physical activity levels, lesion volume or weighted lesion load (all P > 0.208). Moderate intensity cycling may enhance neuroplasticity in people with stroke. This therapy adjuvant could provide opportunities to maximize stroke recovery.

Reactive hyperemia half-time response is associated with skeletal muscle oxygen saturation changes during cycling exercise.

We investigated the relationship between muscle microvascular responses during reactive hyperemia as assessed using near-infrared spectroscopy (NIRS) with changes in skeletal muscle oxygen saturation during exercise. Thirty young untrained adults (M/W: 20/10; 23±5years) completed a maximal cycling exercise test to determine exercise intensities performed on a subsequent visit separated by seven days. At the second visit, post-occlusive reactive hyperemia was measured as changes in NIRS-derived tissue saturation index (TSI) at the left vastus lateralis muscle. Variables of interest included desaturation magnitude, resaturation rate, resaturation half-time, and hyperemic area under the curve. Afterwards, two 4-minute bouts of moderate intensity cycling followed by one bout of severe intensity cycling to fatigue took place while TSI was measured at the vastus lateralis muscle. TSI was averaged across the last 60-s of each moderate intensity bout then averaged together for analysis, and at 60-s into severe exercise. The change in TSI (∆TSI) during exercise is expressed relative to a 20W cycling baseline. On average, the ΔTSI was -3.4±2.4% and -7.2±2.8% during moderate and severe intensity cycling, respectively. Resaturation half-time was correlated with the ΔTSI during moderate (r=-0.42, P=0.01) and severe (r=-0.53, P=0.002) intensity exercise. No other reactive hyperemia variable was found to correlate with ΔTSI. These results indicate that resaturation half-time during reactive hyperemia represents a resting muscle microvascular measure that associates with the degree of skeletal muscle desaturation during exercise in young adults.

Brachial Artery Shear Rate Responses To Sprint Efforts And Moderate Intensity Cycling

Brachial Artery Shear Rate Responses To Sprint Efforts And Moderate Intensity Cycling

The effects of a single bout of moderate-intensity aerobic exercise on visuomotor adaptation and its savings

Performing exercise before or after motor skill learning is thought to have a positive impact on acquisition and retention of motor memories stored in our nervous system. It has been shown that performing 25 min of moderate-intensity aerobic exercise prior to visuomotor adaptation can enhance both visuomotor adaptation and its retention compared to 25 min of rest before the adaptation. To determine whether a single bout of aerobic exercise could actually facilitate the formation of a neural representation associated with a novel visuomotor condition, we examined aftereffects and savings associated with a visuomotor adaptation task following either an exercise or a rest condition. Sixteen healthy young individuals (18–35 years) first experienced 25 min of moderate-intensity cycling or rest, and then adapted to a 30-degree visuomotor rotation condition. Immediately following that, participants experienced a washout session, which was followed by a readaptation session. Results indicated that all subjects adapted to the visuomotor rotation completely, although no difference was found between the cycling and rest conditions. Aftereffects and savings were also observed in both conditions, but with no difference between the conditions. These findings suggest that compared to a short rest session, a single bout of moderate-intensity cycling may not have a greater impact for enhancing visuomotor adaptation and its retention. Further research is needed, in which the effects of certain factors such as exercise intensity, duration and timing are more systematically investigated.

Prolonged exercise shifts ventilatory parameters at the moderate-to-heavy intensity transition.

To quantify the effects of prolonged cycling on the rate of ventilation ([Formula: see text]), frequency of respiration (FR), and tidal volume (VT) associated with the moderate-to-heavy intensity transition. Fourteen endurance-trained cyclists and triathletes (one female) completed an assessment of the moderate-to-heavy intensity transition, determined as the first ventilatory threshold (VT1), before (PRE) and after (POST) two hours of moderate-intensity cycling. The power output, [Formula: see text], FR, and VT associated with VT1 were determined PRE and POST. As previously reported, power output at VT1 significantly decreased by ~ 10% from PRE to POST. The [Formula: see text] associated with VT1 was unchanged from PRE to POST (72 ± 12 vs. 69 ± 13 L.min-1, ∆ -3 ± 5 L.min-1, ∆ -4 ± 8%, P = 0.075), and relatively consistent (within-subject coefficient of variation, 5.4% [3.7, 8.0%]). The [Formula: see text] associated with VT1 was produced with increased FR (27.6 ± 5.8 vs. 31.9 ± 6.5 breaths.min-1, ∆ 4.3 ± 3.1 breaths.min-1, ∆ 16 ± 11%, P = 0.0002) and decreased VT (2.62 ± 0.43 vs. 2.19 ± 0.36 L.breath-1, ∆ -0.44 ± 0.22 L.breath-1, ∆ -16 ± 7%, P = 0.0002) in POST. These data suggest prolonged exercise shifts ventilatory parameters at the moderate-to-heavy intensity transition, but [Formula: see text] remains stable. Real-time monitoring of [Formula: see text] may be a useful means of assessing proximity to the moderate-to-heavy intensity transition during prolonged exercise and is worthy of further research.

Skeletal muscle proteins involved in fatty acid transport influence fatty acid oxidation rates observed during exercise.

Several proteins are implicated in transmembrane fatty acid transport. The purpose of this study was to quantify the variation in fatty acid oxidation rates during exercise explained by skeletal muscle proteins involved in fatty acid transport. Seventeen endurance-trained males underwent a (i) fasted, incremental cycling test to estimate peak whole-body fatty acid oxidation rate (PFO), (ii) resting vastus lateralis microbiopsy, and (iii) 2 h of fed-state, moderate-intensity cycling to estimate whole-body fatty acid oxidation during fed-state exercise (FO). Bivariate correlations and stepwise linear regression models of PFO and FO during 0-30 min (early FO) and 90-120 min(late FO) of continuous cycling were constructed using muscle data. To assess the causal role of transmembrane fatty acid transport in fatty acid oxidation rates during exercise, we measured fatty acid oxidation during in vivo exercise and ex vivo contractions in wild-type and CD36 knock-out mice. We observed a novel, positive association between vastus lateralis FATP1 and PFO and replicated work reporting a positive association between FABPpm and PFO. The stepwise linear regression model of PFO retained CD36, FATP1, FATP4, and FABPpm, explaining ~87% of the variation. Models of early and late FO explained ~61 and ~65% of the variation, respectively. FATP1 and FATP4 emerged as contributors to models of PFO and FO. Mice lacking CD36 had impaired whole-body and muscle fatty acid oxidation during exercise and muscle contractions, respectively. These data suggest that substantial variation in fatty acid oxidation rates during exercise can be explained by skeletal muscle proteins involved in fatty acid transport.

Effects of different exercise patterns on drug craving in female methamphetamine-dependent patients: Evidence from behavior and fNIRS

ObjectiveTo explore the effects of short-term moderate-intensity cycle ergometer and aerobic calisthenics training on drug craving and brain activity. MethodsForty female methamphetamine (MA)-dependent patients were randomly assigned to receive 30 min of either moderate-intensity cycle ergometer or aerobic calisthenics training. Before and after exercise, drug-cue exposure task was used to assess changes in subjective drug craving, and functional near-infrared spectroscopy (fNIRS) was used to assess activation of prefrontal cortex. ResultsAfter the intervention, drug craving was significantly decreased in both groups, and activation of frontal polar area (FPA) was significantly decreased in the cycle ergometer group. Functional connectivity between right dorsolateral prefrontal cortex (DLPFC) and FPA in the aerobic calisthenics group was significantly reduced. Pre-exercise levels of drug craving correlated positively with FPA activation. ConclusionBoth short-term moderate-intensity cycle ergometer and aerobic calisthenics training effectively reduced subjective drug craving in female MA-dependent patients. Cycle ergometer training mainly decreased neural activity in FPA, and likely suppressed drug craving by reducing the episodic memory and pleasure experience of drug-related cues. Aerobic calisthenics training reduced functional connectivity between FPA and right DLPFC, and likely helped subjects reduce the motivation for drug-related behavior and inhibit drug craving.

Prefrontal oxygenation is quantified with time-resolved near-infrared spectroscopy: Effect of sex on baseline oxygenation and the response during exercise.

Using time-resolved near-infrared spectroscopy that enables quantitative analysis of optical properties and oxygenation in cerebral tissues and thereby subject-to-subject comparisons in the variables, this study examined the influence of sex on baseline optical properties and oxygenation in the prefrontal cortex (PFC) and the responses during cycling exercise. Absolute levels of oxygenated- and deoxygenated-hemoglobin concentration (Oxy-Hb and Deoxy-Hb) in bilateral PFC were measured at rest and during unilateral cycling at low- and moderate-intensity in young participants (8 women and 10 men). Unilateral cycling was utilized to evaluate no lateralization of the prefrontal oxygenation responses during exercise. Baseline optical properties of bilateral PFC, defined optical pathlength and reduced scattering coefficient, and their responses during cycling were not different between the sexes. Baseline absolute Oxy-Hb of bilateral PFC was significantly lower in women (37 ± 3 μM) than in men (47 ± 7 μM), whereas absolute Deoxy-Hb revealed no sex-related difference. The absolute Oxy-Hb levels in bilateral PFC during low- and moderate-intensity cycling were also lower in women. However, no sex difference was observed when using changes against the baseline levels to normalize baseline differences. No laterality-related differences were observed in the changes in prefrontal Oxy-Hb and Deoxy-Hb during unilateral cycling. Ascertaining no sex-related difference in optical properties of the PFC, the current findings suggest that baseline absolute level of oxygenation in the PFC is lower in women than in men, likely due to lower oxygen supply rather than higher oxygen utilization, and that prefrontal oxygenation responds similarly during exercise independently of sex.

MiRNA expression in human skeletal muscle following an acute bout of moderate intensity cycle ergometry exercise

Exercise is a potent stimulus that drives both physical and metabolic adaptations, with novel emerging techniques permitting investigation of their molecular mechanisms. The purpose of this study was to utilize small RNA sequencing to determine differentially expressed miRNAs in skeletal muscle of lean humans before and following a single bout of moderate cycling exercise. Total RNA was extracted (RNeasy fibrous tissue kit, Qaigen) from vastus lateralis biopsy samples collected before and after (1.5 hours) a single bout of moderate intensity (75% VO2peak) cycle ergometry exercise perform by 5 unaccustomed volunteer adults (age = 24±3 yrs, BMI = 23.7±3.2). Small RNA library was prepared using the NEXTFLEX® Small RNA-Seq Kit v3. Samples were run on an SP100 flow cell with 51bp paired end reads at TGEN Collaborative Sequencing Center (Phoenix, AZ). Fastq files were analyzed using RStudio 2022.07.1+554 for Windows. All samples were trimmed and aligned to a human reference genome and genome annotation (GRCh38.14, NCBI) using the Rsubread package (Ver 2.10.5). Feature counts were obtained and differentially expressed miRNA were identified using the DESeq2 package (Ver 1.36.0). Raw counts were normalized to sequence length and depth by calculating the reads per kilobase per million to identify uniquely expressed miRNA. Gene Ontology from the DAVID online tool was utilized to explore biological processes associated with the differentially expressed miRNAs. Further analysis of predicted gene targets was conducted using the miRDB.org tool. After alignment, there was an average of 46.5 million alignments across all samples and 23.9 million successful alignments resulting in an average of 51.2% successfully aligned reads to the reference genome. An average of 34 million features were counted across all samples with an average of 3 million counts for all known miRNAs. Differential expression analysis revealed 29 miRNAs were upregulated (log 2 fold change &gt;2, Padj &lt;0.05) following a single bout of moderate aerobic exercise. There were no miRNA significantly down regulated. Among the 29 miRNA, 2 (miRNA 483, l2fc = 2.7±0.68, Padj = 0.14 &amp; miRNA 3909, l2fc = Padj = 0.01) were identified in key biological processes linked to negative regulation of fat cell differentiation, inflammatory response, and blood vessel endothelial cell proliferation involved angiogenesis. One differentially expressed miRNA (miRNA 346 Padj = 0.03) was identified as a positive regulator of canonical Wnt signaling pathway involved in osteoblast differentiation. In sum, we identified 3 key miRNAs in skeletal muscle involved in regulating key biological processes in response to an acute bout of moderate intensity aerobic exercise. Future research should expand these findings by investigating interactions between identified miRNAs and target mRNA(s), and explore the existence of comparable responses in humans with known exercise response deficits such as obesity and/or aging. The study was supported by NIH/NIDDK grant R01DK094062 (CSK), the Mayo Clinic Metabolomics Resource Core through grant number U24DK100469 from the NIH/NIDDK and the Mayo Clinic CTSA grant UL1TR000135 from the National Center for Advancing Translational Sciences. This is the full abstract presented at the American Physiology Summit 2023 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.

Voluntary Hydration with Skimmed Lactose-Free Milk during Exercise in the Heat: Exploring Effectiveness and Tolerance.

Replacement of fluid losses (dehydration) during sports activities in the heat has been investigated with different beverages. Bovine milk has been recommended for post-exercise rehydration, but its use during exercise may provoke gastrointestinal disorders. This study compared voluntary fluid intake, hydration, and incidence and severity of gastrointestinal (GI) disorders during exercise in the heat under three conditions: no drink (ND), water (W), and skimmed lactose-free milk (SM). Sixteen physically active university students exercised at 32 °C and 70% RH for 90 min at 60-75% HRmax while drinking W or SM ad libitum, or ND assigned at random. A questionnaire explored possible GI disorders. Ad libitum intake was higher (p < 0.05) for water (1206.2 mL) than milk (918.8 mL). Dehydration showed significant differences for SM versus W and ND (W = 0.28% BM; SM = -0.07% BM; ND = 1.38% BM, p < 0.05). Urine volume was significantly higher (p < 0.05) in the W condition (W = 220.4 mL; SM = 81.3 mL; ND = 86.1 mL). Thick saliva, belching, and abdominal pain were higher for SM, but scores were low. Skimmed lactose-free milk is a suitable, effective alternative to be consumed as a hydration beverage during moderate-intensity cycling in the heat for 90 min.

Acute exercise and high-glucose ingestion elicit dynamic and individualized responses in systemic markers of redox homeostasis.

Biomarkers of oxidation-reduction (redox) homeostasis are commonly measured in human blood to assess whether certain stimuli (e.g., high-glucose ingestion or acute exercise) lead to a state of oxidative distress (detrimental to health) or oxidative eustress (beneficial to health). Emerging research indicates that redox responses are likely to be highly individualized, yet few studies report individual responses. Furthermore, the effects of complex redox stimuli (e.g., high-glucose-ingestion after exercise) on redox homeostasis remains unclear. We investigated the effect of acute exercise (oxidative eustress), high-glucose ingestion (oxidative distress), and high-glucose ingestion after exercise (both oxidative eu/distress), on commonly measured redox biomarkers in serum/plasma. In a randomized crossover fashion, eight healthy men (age: 28 ± 4 years; BMI: 24.5 ± 1.5 kg/m2 [mean ± SD]) completed two separate testing conditions; 1) consumption of a high-glucose mixed-nutrient meal (45% carbohydrate [1.1 g glucose.kg-1], 20% protein, and 35% fat) at rest (control trial), and 2) consumption of the same meal 3 h and 24 h after 1 h of moderate-intensity cycling exercise (exercise trial). Plasma and serum were analyzed for an array of commonly studied redox biomarkers. Oxidative stress and antioxidant defense markers (hydrogen peroxide, 8-isoprostanes, catalase, superoxide dismutase, and nitrate levels) increased immediately after exercise (p < 0.05), whereas nitric oxide activity and thiobarbituric acid reactive substances (TBARS) remained similar to baseline (p > 0.118). Nitric oxide activity and nitrate levels decreased at 3 h post-exercise compared to pre-exercise baseline levels. Depending on when the high-glucose mixed nutrient meal was ingested and the postprandial timepoint investigated, oxidative stress and antioxidant defense biomarkers either increased (hydrogen peroxide, TBARS, and superoxide dismutase), decreased (hydrogen peroxide, 8-isoprostanes, superoxide dismutase, nitric oxide activity, nitrate, and nitrite), or remained similar to pre-meal baseline levels (hydrogen peroxide, 8-isoprostanes, TBARS, catalase, superoxide dismutase and nitrite). Redox responses exhibited large inter-individual variability in the magnitude and/or direction of responses. Findings highlight the necessity to interpret redox biomarkers in the context of the individual, biomarker measured, and stimuli observed. Individual redox responsiveness may be of physiological relevance and should be explored as a potential means to inform personalized redox intervention.

Differences in the prefrontal cortex responses of healthy young men performing either water-based or land-based exercise at light to moderate intensity

Cerebral blood flow increases more during water-based exercise than land-based exercise owing to the effects of end-tidal CO2 (PETCO2) and mean arterial pressure (MAP) changes due to water immersion. However, it is unclear whether oxygenated hemoglobin (oxy-Hb) concentrations in the prefrontal cortex (PFC) are increased more by water-based or land-based exercise. We hypothesized that oxy-Hb concentrations in the PFC are higher during water-based exercise than land-based exercise when the exercise intensity is matched. To test this hypothesis, 10 healthy participants (age: 24.2 ± 1.7 years; height: 1.75 ± 0.04 m; weight: 69.5 ± 5.2 kg) performed light- to moderate-intensity cycling exercise in water (water-based cycling (WC); chest-high water at 30 °C) and on land (LC). Stroke volume, cardio output, heart rate, MAP, respiratory rate, PETCO2, and oxy-Hb in the PFC were assessed during 15 min of exercise, with exercise intensity increased every 5 min. Both WC and LC significantly increased oxy-Hb concentrations in the PFC as exercise intensity was increased (intensity effect: p < 0.001). There was no significant difference in oxy-Hb concentrations during WC and LC in most prefrontal areas, although significant differences were found in areas corresponding to the left dorsolateral PFC (exercise effect: p < 0.001). Thus, WC and LC increase oxy-Hb concentrations in the PFC in a similar manner with increasing exercise intensity, but part of the PFC exhibits enhanced oxy-Hb levels during WC. The neural response of the PFC may differ during water-based and land-based exercise owing to differences in external information associated with water immersion.