1-minute Duration Research Articles

TIME IS OF THE ESSENCE: RELIABLE MEASUREMENT OF HEART RATE VARIABILITY IN OLDER ADULTS

Abstract Heart rate variability (HRV) decreases with age and is an important correlate of psychosocial and physical health. Recommendations for the minimum duration of EKG to accurately derive HRV vary from 1 minute to several minutes. However, the definition of “accuracy” or reliability depends on study design, including whether the focus of the study is on stable or momentary between-person differences or within-person changes in HRV. In a sample of 216 older adults (Mage = 72.7, 62.5% women), ECG was measured at 1000 Hz for 10 minutes every 6 months for up to 6.5 years. HRV was high-frequency power (0.15–0.40). A generalizability study determined the variance due to minute, occasion, person, and their interactions. The most variance was due to idiosyncratic occasion differences (46%), followed by stable person variance (18%). A decision study determined how accuracy in HRV measurement could be achieved. Between-person differences in HRV at a specific occasion could be reliably measured with 6 minutes of ECG (.80); within-person changes in HRV between occasions could be reliably measured with 3 minutes of ECG (.83). For stable individual differences, 10 or more occasions of 1-minute duration produced a more reliable estimate (.73) than increasing the length of a single ECG recording to 10 minutes (.25). The necessary duration of ECG for measuring HRV reliably depends on the study design and research question. Ultra-short durations (1-2 minutes) are generally not recommended for older adults.

Does Stretching Training Influence Muscular Strength? A Systematic Review With Meta-Analysis and Meta-Regression.

Thomas, E, Ficarra, S, Nunes, JP, Paoli, A, Bellafiore, M, Palma, A, and Bianco, A. Does stretching training influence muscular strength? A systematic review with meta-analysis and meta-regression. J Strength Cond Res 37(5): 1145-1156, 2023-The aim of this study was to review articles that performed stretching training and evaluated the effects on muscular strength. Literature search was performed using 3 databases. Studies were included if they compared the effects on strength following stretching training vs. a nontraining control group or stretching training combined with resistance training (RT) vs. an RT-only group, after at least 4 weeks of intervention. The meta-analyses were performed using a random-effect model with Hedges' g effect size (ES). A total of 35 studies ( n = 1,179 subjects) were included in this review. The interventions lasted for a mean period of 8 weeks (range, 4-24 weeks), 3-4 days per week, applying approximately 4 sets of stretching of approximately 1-minute duration. The meta-analysis for the stretching vs. nontraining control group showed a significant small effect on improving dynamic (k = 14; ES = 0.33; p = 0.007) but not isometric strength (k = 8; ES = 0.10; p = 0.377), following static stretching programs (k = 17; ES = 0.28; p = 0.006). When stretching was added to RT interventions, the main analysis indicated no significant effect (k = 17; ES = -0.15; p = 0.136); however, moderator analysis indicated that performing stretching before RT sessions has a small but negative effect (k = 7; ES = -0.43; p = 0.014); the meta-regression revealed a significant negative association with study length (β = -0.100; p = 0.004). Chronic static stretching programs increase dynamic muscular strength to a small magnitude. Performing stretching before RT and for a prolonged time (>8 weeks) can blunt the strength gains to a small-to-moderate magnitude. Performing stretching in sessions distant from RT sessions might be a strategy to not hinder strength development.

Effect of aquatic exercise on mental health, functional autonomy, and oxidative damages in diabetes elderly individuals

ABSTRACT This study investigated the effect of aquatic exercise on mental health, functional autonomy, and oxidative dysfunction in elderly with DM2. A total of 104 elderly were included in the longitudinal clinical study and were attributed to the diabetes group (n = 30) and the non-diabetic group (n = 29). Both groups were involved in the aquatic exercise (nine exercises; 3 sets x 1-minute duration each; linear intensity and frequency measured twice a week) for 12 weeks. The assessments of mental health, functional autonomy, and oxidative dysfunction were done. All results were evaluated at baseline and 12 weeks later. The values of the following variable scores decreased in the DM2 group after participation in the aquatic exercise: depression (−56 ± 2 scores; 57%), anxiety (−8.2 ± 2 scores; 41%), stress (−3.1 ± 0.3 scores; 32%), and sleep (−3. 7 ± 1.3 points; 51%); an improvement in Berg scores was observed (+53.1 ± 2 points; 8%), Tug tests (−6.1 ± 0.7 points; 25%), carbonyl groups (−0.048 ± 0.01 nnmol/mg/protein; 49%), and total thiol (+0.33 ± 0.08 nnmol/mg/protein; 83%). We have concluded that a linear intensity aquatic exercise program improves mental health, functional autonomy, and oxidative dysfunction in elderly with DM2.

Intermittent Hypoxemia in Preterm Infants: A Potential Proinflammatory Process.

A major consequence of prematurity is intermittent hypoxemia (IH). Data from both adult studies and neonatal animal models suggest that IH is proinflammatory; however, there is limited data in preterm infants. Here, we assess the relationship between IH and systemic inflammation, namely, serum C-reactive protein (CRP) in preterm infants. Serum CRP was measured at 30 days of life, at the time of peak IH frequency. IH measures (e.g., per cent time in hypoxemia, frequency, duration) were calculated the week prior to CRP collection. Statistical analyses were based on Spearman's correlation. A total of 26 infants were included. Median gestational age and birth weight were 274/7 weeks and 980 g, respectively. There were positive correlations between primary IH measures and CRP levels, especially for events longer than 1-minute duration (r range: 0.56-0.74, all p < 0.01). We demonstrate that IH is associated with increased CRP for the first time in preterm infants. Our findings are consistent with studies from adults and neonatal animal models suggesting that IH is a proinflammatory process. · IH events are common.. · IH is associated with elevated C-reactive protein.. · Longer IH events (>1 min) are of most significance..

Muscle oxygenation in Type 1 diabetic and non-diabetic patients with and without chronic compartment syndrome.

BackgroundType 1 diabetic patients and non-diabetic patients were referred for evaluation for chronic exertional compartment syndrome (CECS) based on clinical examination and complaints of activity-related leg pain in the region of the tibialis anterior muscle. Previous studies using near-infrared spectroscopy (NIRS) showed greater deoxygenation during exercise for CECS patients versus healthy controls; however, this comparison has not been done for diabetic CECS patients.MethodsWe used NIRS to test for differences in oxygenation kinetics for Type 1 diabetic patients diagnosed with (CECS-diabetics, n = 9) versus diabetic patients without (CON-diabetics, n = 10) leg anterior chronic exertional compartment syndrome. Comparisons were also made between non-diabetic CECS patients (n = 11) and healthy controls (CON, n = 10). The experimental protocol consisted of thigh arterial cuff occlusion (AO, 1-minute duration), and treadmill running to reproduce symptoms. NIRS variables generated were resting StO2%, and oxygen recovery following AO. Also, during and following treadmill running the magnitude of deoxygenation and oxygen recovery, respectively, were determined.ResultsThere was no difference in resting StO2% between CECS-diabetics (78.2±12.6%) vs. CON-diabetics (69.1±20.8%), or between CECS (69.3±16.2) vs. CON (75.9±11.2%). However, oxygen recovery following AO was significantly slower for CECS (1.8±0.8%/sec) vs. CON (3.8±1.7%/sec) (P = 0.002); these data were not different between the diabetic groups. StO2% during exercise was lower (greater deoxygenation) for CECS-diabetics (6.3±8.6%) vs. CON-diabetics (40.4±22.0%), and for CECS (11.3±16.8%) vs. CON (34.1±21.2%) (P<0.05 for both). The rate of oxygen recovery post exercise was faster for CECS-diabetics (3.5±2.6%/sec) vs. CON-diabetics (1.4±0.8%/sec) (P = 0.04), and there was a tendency of difference for CECS (3.1±1.4%/sec) vs. CON (1.9±1.3%/sec) (P = 0.05).ConclusionThe greater deoxygenation during treadmill running for the CECS-diabetics group (vs. CON-diabetics) is in line with previous studies (and with the present study) that compared non-diabetic CECS patients with healthy controls. Our findings could suggest that NIRS may be useful as a diagnostic tool for assessing Type 1 diabetic patients suspected of CECS.

Effect of Various Intensities of Short-Term Interval Training on Oxygen Uptake Kinetics

Oxygen (O2) uptake kinetics reflect the rate at which an individual’s oxygen consumption (VO2) changes to meet a new metabolic demand, such as an increase or decrease in exercise intensity. O2 uptake kinetics can indicate cardiovascular and metabolic fitness and are described by the time variable, τ (tau), of the exponential equation describing the change in VO2. With training τ decreases, indicating a more rapid increase in VO2 to meet the new metabolic demand. Interval training at supramaximal (&gt;100% VO2max) intensities has been shown to elicit similar improvements in O2 uptake kinetics to traditional endurance training. This study looked to determine the optimal intensity of interval training for eliciting improvements in O2 uptake kinetics. Fifteen recreationally active individuals (males: n=9, age = 23.3±3.3 years, VO2max = 44.2±6.5 ml O2•min-1•kg-1; females: n=6, age = 21.5±0.7 years, VO2max = 39.7±5.4 ml O2•min-1•kg-1) participated in 12 training sessions over 4 weeks. To measure O2 uptake kinetics subjects completed three step transitions from loadless (~25W) to low work-rate (~80W) cycling, prior and following training. Each subject was randomly assigned to one of three intensities - high-intensity interval training (HIIT ~120% VO2max), moderate-intensity interval training (MIIT ~90% VO2max), and low-intensity interval training (LIIT ~65% VO2max). Each session consisted of 8-12 intervals of 1-minute duration with 1-minute recovery on a stationary bicycle at the prescribed relative intensity. No significant differences between groups were observed in changes in τ (Δτ: LIIT: 3.1±8.3s; MIIT: -0.59±12.4s; HIIT: 6.2±6.0s).

Effect of Durations of Wheelchair Tilt-in-Space and Recline on Skin Perfusion Over the Ischial Tuberosity in People With Spinal Cord Injury

ObjectiveTo compare the efficacy of various durations of wheelchair tilt-in-space and recline on enhancing skin perfusion over the ischial tuberosity in people with spinal cord injury (SCI). DesignRepeated-measures, intervention and outcomes measure design. SettingUniversity research laboratory. ParticipantsPower wheelchair users with SCI (N=9). InterventionsThree protocols of various durations (3min, 1min, and 0min) of wheelchair tilt-in-space and recline were randomly assigned to the participants. Each protocol consisted of a baseline 15-minute sitting, a duration of 0- to 3-minute reclined and tilted, a second 15-minute sitting, and a 5-minute recovery. The position at the baseline and the second sitting was no tilt/recline of the participant and at the reclined and tilted and recovery was at 35° tilt-in-space and 120° recline. Main Outcome MeasuresSkin perfusion response to tilt and recline was assessed by laser Doppler and was normalized to mean skin perfusion at the baseline sitting. ResultsThe results showed that mean skin perfusion during recovery at the 3-minute duration was significantly higher than that at the 1-minute duration (P<.017) and mean skin perfusion was not significantly different between the 1-minute and 0-minute durations (not significant). Skin perfusion during the second sitting was significantly higher at the 3-minute duration than at the 1-minute and 0-minute durations (P<.017). ConclusionsOur findings suggest that performing the 3-minute duration of wheelchair tilt-in-space and recline is more effective than the 1-minute duration in enhancing skin perfusion of weight-bearing soft tissues.

Transpupillary Thermotherapy of Subfoveal Choroidal Neovascularization Secondary to Pathologic Myopia

To assess the safety and effectiveness of transpupillary thermotherapy treatment of subfoveal choroidal neovascular membrane secondary to pathologic myopia. Seventy-four patients (74 eyes) with pathologic myopia underwent transpupillary thermotherapy treatment using a 3.0-mm spot size, 1-minute duration, and 520-mW power delivered through a contact lens. Clinical evaluation included measurement of best-corrected Snellen visual acuity, slit-lamp biomicroscopy, fundus color photography, and fluorescein angiography. Sixty-four eyes (86%) received one treatment session. Six eyes (8%) improved 0.1 logarithm of the minimum angle of resolution (LogMAR) visual acuity post-treatment, 10 eyes (13.5%) lost more than 0.2 LogMAR acuity, and another 10 eyes (13.5%) lost 0.1 LogMAR acuity. The remaining 48 eyes (65%) had unchanged visual acuity after the last follow-up visit. Transpupillary thermotherapy preserves vision in patients with choroidal neovascular membrane associated with pathologic myopia. Younger patients and eyes with higher refractive error are more likely to benefit from treatment.

SUBTHRESHOLD TRANSPUPILLARY THERMOTHERAPY FOR EARLY RESOLUTION OF FOVEAL SUBRETINAL FLUID IN CHOROIDAL METASTASIS

To report the effectiveness of subthreshold transpupillary thermotherapy (TTT) in the early resolution of subretinal fluid at the fovea in solitary choroidal metastasis. : Three consecutive patients who had adenocarcinoma of the lung with choroidal metastasis and macular subretinal fluid were treated by subthreshold TTT. Tumor response and fluorescein angiographic and visual results were recorded. Fluorescein angiography revealed solitary choroidal metastasis at the posterior pole with subretinal fluid in all patients. Initial best-corrected visual acuity in Patient 1, a 57-year-old man, was 40/200. Instead of usual high laser intensity, three applications of TTT, 400-mW power, 3-mm size, and 1-minute duration, were performed over the tumor mass. Repeated treatment with the same regimen was performed after 1 week. Visual acuity improved to 20/25 2 months after treatment. Best-corrected visual acuity in Patient 2, a 68-year-old woman, was 10/200 in the right eye before treatment. Visual acuity improved to 80/200 after treatment and remained stable for 14 months. Visual acuity improved from 20/100 to 20/60 in a third patient 2 months after treatment. The disappearance of subretinal fluid over the fovea was noted by fluorescein angiography 2 months after laser treatment and remained stable until the end of follow-up. Improvement of visual acuity and cessation of fluorescein leakage in the tumor showed that subthreshold (i.e., biomicroscopically invisible laser effect) TTT served as an effective treatment modality in the early resolution of macular subretinal fluid in choroidal metastasis. Multiple sessions of subthreshold TTT are safe to apply very close to the macula.

Transpupillary thermotherapy of juxtafoveal recurrent choroidal neovascularization.

To evaluate the effectiveness of low power transpupillary thermotherapy (TTT) in treating juxtafoveal recurrent choroidal neovascularization (CNV) after laser photocoagulation in patients with age-related macular degeneration (ARMD). Eight eyes of eight patients with ARMD and juxtafoveal recurrent CNV were treated with low power TTT, delivered using an 810-nm diode laser with 350 mW, 2.0 mm spot, and 1-minute duration. Visual acuity (VA) ranged from 20/100 to 20/50. Treatment effect was evaluated by fluorescein angiography, indocyanine green angiography, and VA measurements (Early Treatment Diabetic Retinopathy Study) at 1-week, 2-week, and monthly follow-up visits. No retinal damage was visible ophthalmoscopically during treatment. At the first follow-up visit, seven eyes had obliteration of CNV and one eye required a second TTT application. VA was unchanged in six eyes, improved in one eye, and worsened in one eye. Recurrences occurred in all eyes between 1 and 7 months after TTT and were treated with photodynamic therapy (PDT). More than two PDT treatments were performed in each eye in the year after recurrence. Low power TTT is as able to close juxtafoveal recurrent CNV as is high power conventional laser photocoagulation but does not prevent recurrences. Further intervention with TTT in order to treat recurrences is under investigation.

Calcification in choroidal melanoma after transpupillary thermotherapy

PURPOSE: To report the response of calcification in choroidal melanoma after transpupillary thermotherapy. METHODS: Interventional case report. A 66-year-old male with a posterior uveal melanoma measuring 10 × 8 × 4.4 mm underwent infrared diode laser transpupillary thermotherapy three times, each 12 weeks apart. For each treatment, a 3-mm spot size of 1-minute duration was used, and the power setting varied between 450 mW and 500 mW. RESULTS: Two months after the last transpupillary thermotherapy session, A- and B-mode echographic patterns strongly suggestive of intratumor calcification were observed. The tumor regressed to 2.8 mm in thickness, but calcification persisted. Local recurrence or distant metastasis was not detected during a follow-up of 14 months. CONCLUSION: Clinically detectable calcification is extremely rare in choroidal melanomas. Tumor regression with slowly progressive calcification may occur after transpupillary thermotherapy.

The sympathetic nervous system modulates perception and reflex responses to gut distention in humans

Background/Aims : Intestinal distention induces perception and gut reflexes via sympathetic and vagal pathways, but the modulatory mechanisms of such responses remain obscure. The aim of this study was to determine the effects of sympathetic nervous activity on sympathetic and vagal reflexes as well as on intestinal and somatic perception. Methods : In 9 healthy volunteers, proximal duodenal distentions were produced in 4-mL increments and hand transcutaneous electrical nerve stimulation was produced in 3-mA increments. Increasing stimuli of 1-minute duration were randomly performed at 10-minute intervals both with and without sympathetic activation (induced by means of lower body negative pressure). Intestinal and somatic perception was scored by specific questionnaires; vagal enterogastric and sympathetic intestinointestinal relaxatory reflexes were simultaneously measured by gastric and distal duodenal barostats. Results : Sympathetic activation significantly heightened perception of intestinal distention without modifying perception of somatic stimuli (perception scores increased by 41% and −2%, respectively). The reflex responses to duodenal distention significantly increased during sympathetic activation both in the stomach and in the intestine (relaxation increased by 91% and 69%, respectively; P < 0.05 for both). Conclusions : Activation of the sympathetic nervous system selectively increases visceral but not somatic sensitivity and enhances both vagally and sympathetically driven reflexes in the gut.

Selective dysfunction of mechanosensitive intestinal afferents in irritable bowel syndrome

Background/Aims : Experimental studies have shown gut hypersensitivity in irritable bowel syndrome. The aim of this study was to determine whether heightened perception of gut distention in irritable bowel syndrome is related to either decreased gut compliance, altered mechanosensitive afferents, or nonspecific sensory dysfunction. Methods : In 17 patients with irritable bowel syndrome and 15 healthy controls, stimulus-related perception of (1) intestinal balloon distentions, (2) transmucosal electrical nerve stimulation (15 Hz, 100 μs), and (3) somatic transcutaneous electrical nerve stimulation (100 Hz, 100 μs) was measured. Individual stimuli of 1-minute duration were randomly applied at 5-minute intervals. Results : Patients tolerated smaller intestinal volumes than controls (33 ± 3 mL vs. 43 ± 4 mL, respectively; mean ± SE; P < 0.05), whereas both intestinal compliance and perception of transmucosal electrical nerve stimulation were normal (patients tolerated 58 ± 5 mA and healthy subjects tolerated 69 ± 5 mA). Interestingly, patients perceived both stimuli more diffusely than controls; 48% ± 9% distentions and 52% ± 9% electrical stimuli were perceived over more than one abdominal region vs. 21% ± 9% and 18% ± 6%, respectively, in controls ( P < 0.05 for both). In contrast to gut distentions, patients showed higher tolerance of somatic stimuli than controls (68 ± 7 mA vs. 42 ± 6 mA, respectively; P < 0.05). Conclusions : Patients with irritable bowel syndrome show selective hypersensitivity of intestinal mechanosensitive pathways associated with a nonspecific, probably central dysfunction of viscerosomatic referral.

Behavior and pheromone studies withAttagenus elongatulus Casey (Coleoptera: Dermestidae)

Males ofAttagenus elongatulus Casey responded to a source of female odor with a characteristic sequence of actions which included: extension of the antennae, elevation of the body by leg extension, rapid zig-zag running, and intermittent bobbing up and down. The courtship sequence also consisted of several activities and was usually followed by a typical copulatory act of less than 1-minute duration. Virgin females exhibited calling behavior which was associated with pheromone release. Female calling activity, female pheromone content, and male responsiveness followed a diurnal cycle with peak values occurring during the earlier hours of the 16L∶8D photoperiod. Quantitative bioassay indicated that a 50% male response level (RD50) occurred at ca. 0.014 female equivalent (FE) exposure.

NONNUTRITIVE SUCKING IN NEWBORNS UNDER VISUAL AND AUDITORY STIMULATION

Light and sound stimulations of 1-minute duration were presented to 10 newborn infants on each of their first 5 days of life. Diferential stimulus effects on frequency of sucking "bursts" were observed. No differential effects were found on time spent sucking during periods of stimulation. An inverted U-shaped relation was found between level of light intensity and number of sucking bursts. Sound stimulation decreased burst frequency. No additive efects of combined light and sound stimulation were found. Stimulus change affected sucking bursts but did not inhibit sucking. Reliable individual differences were found for average number of sucking bursts per minute, burst length, interburst interval length, and seconds of sucking per minute.