Single Daily Session Research Articles

Cardiometabolic and Cellular Adaptations to Multiple vs. Single Daily HIIT Sessions in Wistar Rats: Impact of Short-Term Detraining.

Multiple short daily bouts of HIIT are more effective than single daily sessions in improving cardiometabolic and cellular adaptations in rats. We hypothesize that a short period of detraining is sufficient to abolish the superior adaptive responses to multiple versus single daily sessions of HIIT in rats. Male rats were divided into untrained, 1xHIIT, and 3xHIIT groups. Over eight weeks, the 1xHIIT group performed 115 min single daily sessions of HIIT, while the 3xHIIT group performed three 5 min sessions with 4 h intervals. After training, both groups remained sedentary for four weeks (detraining). Resting oxygen consumption (VO2), body composition, glucose/insulin tolerance, and blood pressure were recorded. After euthanasia, cardiac function/histology and gastrocnemius mitochondrial density were analyzed. After training, both 1xHIIT and 3xHIIT protocols induced similar improvements in VO2, maximal oxygen uptake (VO2max), cardiac function/hypertrophy, and gastrocnemius mitochondrial density. These effects were maintained even after detraining. Only the 3xHIIT protocol improved insulin sensitivity. After detraining, this effect was abolished. After training, both 1xHIIT and 3xHIIT protocols reduced adiposity. After detraining, the adiposity increased in both groups, with a more pronounced increase in the 3xHIIT rats. A four-week detraining period abolishes the superior adaptive responses to multiple versus single daily HIIT sessions in rats.

Accumulated HIIT inhibits anxiety and depression, improves cognitive function, and memory-related proteins in the hippocampus of aged rats.

This study aimed to compare the effects of High-Intensity Interval Training (HIIT) performed in a single session(1xHIIT) versus three daily sessions (3xHIIT) on fitness level and behavior of aged rats. Eighteen-month-old Wistar rats were assigned to Untrained (UN), 1xHIIT, or 3xHIIT (n = 12/group). Both groups, 1xHIIT and 3xHIIT, performed 15min of a treadmill running HIIT protocol during 8 weeks. 1xHIIT protocol consisted of a single daily session of 15min, while the 3xHIIT performed three daily sessions of 5min with a 4h interval between the sessions. Morris Water Maze (MWM) task was used to evaluate spatial learning and memory. Splash test, Forced Swim test, and Elevated Plus Maze task (EPM) were used to evaluate anhedonic, depressive-like, and anxious behaviors, respectively. Rats were euthanized, and the hippocampus was harvested for western blot analyses (CaMKII and BDNF). Both HIIT protocols improved VO2max and spatial memory. Notably, only the 3xHIIT protocol attenuated anxious and depressive-like behaviors. Western blot analyses of the hippocampus revealed that both HIIT protocols increased BDNF levels. BDNF levels were higher in the 3xHIIT when compared with 1xHIIT group, and we observed increasement of the CamKII levels just in the 3x HIIT group. Therefore, this study provides evidence indicating that accumulated HIIT sessions is more effective than traditional daily HIIT sessions in improving fitness level, cognitive function, memory, inhibiting the development of mood disorders, and enhancing BDNF and CaMKII levels in the hippocampus of aged rats.

Superior cardiometabolic and cellular adaptive responses to multiple versus single daily sessions of high-intensity interval training in Wistar rats

This study aimed to compare in rats the cardiometabolic and cellular adaptative responses to 8 weeks of high-intensity interval training (HIIT) performed in a single (1xHIIT) or three shorter daily sessions (3xHIIT). Male Wistar rats were assigned to untrained (n = 10), 1xHIIT (n = 10), and 3xHIIT (n = 10) groups. Both HIIT groups performed 15 min of a treadmill run five times per week for 8 weeks. The 1xHIIT performed single daily sessions of 15 min, and the 3xHIIT performed three daily sessions of 5 min with an interval of 4 h between sessions. Resting VO2 and VO2max were measured using a metabolic chamber; blood pressure and heart rate were measured by plethysmography; body composition was estimated by DEXA; Glucose and insulin tolerance tests were performed; after euthanasia, hearts, gastrocnemius, and visceral fat were harvested for analysis of cardiac function, histology, and morphology. Mitochondrial densities of the gastrocnemius and left ventricle muscles were determined by electron microscopy. 3xHIIT induced similar positive adaptative responses to 1xHIIT on resting VO2 and VO2max, cardiac function, and mitochondria density. 3xHIIT was superior to 1xHIIT in reducing visceral fat weight and adipocyte size and improving insulin tolerance. Multiple short daily bouts of HIIT may be superior to single HIIT daily sessions in improving cardiometabolic and cellular adaptations in rats.

Accumulated High-intensity Interval Training Protocol: A New Approach to Study Health Markers in Wistar Rats.

High-Intensity Interval Training (HIIT) and accumulated exercises are two time-efficient programs to improve health in humans and animal models. However, to date, there are no studies on whether HIIT performed in an accumulated fashion is as effective as a traditional HIIT performed with single daily sessions in improving health markers. This paper presents the effects of a new HIIT protocol, called accumulated HIIT, on body weight gain, maximal oxygen consumption (VO2max), and cardiac hypertrophy in young Wistar rats. Sixty-day-old male Wistar rats were assigned to three groups: untrained (UN; n = 16), HIIT performed with single daily sessions (1-HIIT; n = 16), and HIIT performed with three daily sessions (3-HIIT; n = 16). Body weight and VO2max were recorded before and after the training period. The VO2max measurements were taken using a metabolic analyzer at the maximal running velocity (Vmax). The training was performed for both HIIT groups five days per week over eight weeks with the same weekly progression of the exercise intensity (85-100% Vmax). The 1-HIIT group performed single daily sessions (6 bouts of 1 min interspersed with 1 min of passive recovery). The 3-HIIT group performed three daily sessions (2 bouts of 1 min interspersed with 1 min of passive recovery with an interval of 4 h between bouts). After the last VO2max test, the rats were euthanized, and their hearts were harvested and weighed. The results showed that 3-HIIT had similar beneficial effects to 1-HIIT in preventing body weight gain, improving VO2max, and inducing cardiac hypertrophy. These findings reveal for the first time the efficacy of an accumulated HIIT protocol on the health markers of young Wistar rats. This new HIIT protocol may be more feasible than traditional HIIT protocols as exercise can be split into very short sessions throughout a day in this new approach.

Estradiol effects on spatial memory in women

To examine the role of estradiol in hippocampal-dependent spatial memory in women, 86 female undergraduates were tested in a virtual Morris water task (VMWT), a virtual radial arm maze (VRAM), and a mental rotation task (MRT) within a single daily session. The VMWT and RAM were also administered 24 h later to examine the effects of estradiol on memory consolidation. Women on oral contraceptives (OCs) or those who were naturally cycling and exhibited low estradiol (LE) or high estradiol (HE), as determined by salivary assays, were included. At the start of day two, the HE group showed superior spatial reference memory on the VMWT relative to the LE group, as evidenced by significantly shorter distances navigating to the hidden platform. The LE group also had the poorest probe trial performance at the start of day two compared to both other groups. There were no group differences in performance on the RAM or MRT. These results provide support for estradiol’s role in the consolidation of spatial reference memory in women, and emphasize the differential sensitivities of various virtual memory tasks in assessing spatial memory function in women.

Anatomy of a failure: Chronic interventional paired associative stimulation in stroke (CIPASS)

Paired associative stimulation (PAS) is a specific non-invasive brain stimulations technique that allows to modulate motor plasticity in both patients and healthy participants. Our goal was to demonstrate a therapeutic interest for PAS with a lasting increase in motor cortex plasticity for extensor wrist (ECR) muscles and an improvement in upper limb function after 5 days of daily stimulation, in subacute post-stroke patients. A total of 24 patients were included in a double-blind, placebo-controlled trial and randomly assigned to one of two groups (PAS or sham). In the PAS condition, patients underwent a 5-day course of electrical peripheral stimulation, combined with magnetic cortical stimulation, which was applied to the ECR muscle in a single daily session at a frequency of 0.1 Hz for 30 min. It was associated with 2 hours of conventional physiotherapy. Variations in the motor evoked potential (MEP) surface area of the ECR muscle and Upper-Extremity Fugl-Meyer Motor Scale scores were analyzed up to Day 12. No significant difference was observed between the two groups on either electrophysiological or motor parameters. However, repetitive PAS sessions did seem to have an influence on patients with low initial cortical excitability. The negative results underlines some methodological considerations: the inappropriate characteristic of post-stroke MEP for assessing motor recovery, the considerable variability in PAS effects between patients and across the sessions, the heterogeneity of post-stroke population. Five days of daily PAS session failed to improve motor functions in post-stroke patients: PAS cannot be recommended as therapeutic adjuvant in post-stroke rehabilitation.

Five-day course of paired associative stimulation fails to improve motor function in stroke patients

BackgroundNon-invasive brain stimulation has been studied as a therapeutic adjunct for upper-limb recovery in patients with stroke. One type of stimulation, paired associative stimulation (PAS), has effects on plasticity in both patients and healthy participants. Lasting several hours, these effects are reversible and topographically specific. ObjectiveThe goal was to investigate the presence of a lasting increase in motor cortex plasticity for extensor wrist muscles — extensor carpi radialis (ECR) — and an improvement in upper-limb function after 5 days of daily PAS in patients at the subacute post-stroke stage. MethodsA total of 24 patients (mean [SD] age 50.1 [12.1] years, weeks since stroke 10.1 [5.3]) were included in a double-blind, placebo-controlled trial and randomly assigned to the PAS or sham group (n=13 and n=11). For the PAS group, patients underwent a 5-day course of electrical peripheral stimulation combined with magnetic cortical stimulation applied to the ECR muscle in a single daily session at 0.1Hz for 30min; patients with sham treatment received minimal cortical stimulation. Both patient groups underwent 2 hr of conventional physiotherapy. Variations in the motor evoked potential (MEP) surface area of the ECR muscle and Fugl–Meyer Assessment–Upper-Limb motor scores were analysed up to day 12. ResultsThe 2 groups did not differ in electrophysiological or motor parameters. Repeated PAS sessions seemed to affect only patients with low initial cortical excitability. We found considerable variability in PAS effects between patients and across the sessions. ConclusionWe failed to induce a lasting effect with PAS in the present study. PAS does not seem to be the main method for post-stroke brain stimulation. Perhaps recruitment of patients could be more selective, possibly targeting those with a wide altered ipsilesional corticomotor pathway.

The rabbit as a behavioral model system for magnetic resonance imaging

BackgroundfMRI requires that subjects not move during image acquisition. This has been achieved by instructing people not to move, or by anesthetizing experimental animal subjects to induce immobility. We have demonstrated that a surgically implanted headbolt onto the skull of a rabbit allows their brain to be imaged comfortably while the animal is awake. This article provides a detailed method for the preparation. New methodWe took advantage of the rabbit's tolerance for restraint to image the brain while holding the head at the standard stereotaxic angle. Visual stimulation was produced by flashing green LEDs and whisker stimulation was done by powering a small coil of wire attached to a fiber band. Blinking was recorded with an infrared emitter/detector directed at the eye with fiber-optic cabling. ResultsResults indicate that a single daily session of habituation is sufficient to produce adequate immobility on subsequent days to avoid movement artifacts. Results include high resolution images in the stereotaxic plane of the rabbit. Comparison with existing method(s)We see no degradation or distortion of MR signal, and the headbolt provides a means for rapid realignment of the head in the magnet from day to day, and across subjects. The use of rabbits instead of rodents allows much shorter periods of habituation, and the rabbit allows behavior to be observed during the day while the animal is in its normal wake cycle. ConclusionsThe natural tolerance of the rabbit for restraint makes it a valuable subject for MRI studies of the brain.

Effects of 10 Hz Repetitive Transcranial Magnetic Stimulation of the Left Dorsolateral Prefrontal Cortex in Disorders of Consciousness.

While repetitive transcranial magnetic stimulation (rTMS) has been applied in treatment of patients with disorders of consciousness (DOC), a standardized stimulation protocol has not been proposed, and its therapeutic effects are inconsistently documented. To assess the efficacy of rTMS in improving consciousness in patients with persistent minimally conscious state (MCS) or unresponsive wakefulness syndrome (UWS), previously known as vegetative state (VS). A prospective single-blinded study, with selected subjects, was carried out. In total, 16 patients (5 MCS and 11 VS/UWS) with chronic DOC were included. All patients received active 10 Hz rTMS at the left dorsolateral prefrontal cortex (DLPFC), at one session per day, for 20 consecutive days. A single daily session of stimulation consisted of 1,000 pulses (10 s of 10 Hz trains; repeated 10 times with an inter-train interval of 60 s; and 11 min and 40 s for total session). The main outcome measures were changes in the total score on the JFK Coma Recovery Scale-Revised (CRS-R) scale. Additional measures were the impressions of caregivers after the conclusion of the interventions, which were assessed using the Clinical Global Impression-Improvement (CGI-I) scale. The CRS-R scores were increased in all 5 MCS patients and 4 of 11 VS/UWS patients, while a significant enhancement of CRS-R scores was observed compared to the baseline in all participants (p = 0.007). However, the improvement was more notable in MCS patients (p = 0.042) than their VS/UWS counterparts (p = 0.066). Based on the CGI-I scores, two patients improved considerably, two improved, six minimally improved, six experienced no change, and none deteriorated. Good concordance was seen between the CGI-I result and the increases in CRS-R scores. Treatment of 10 Hz multisession rTMS applied to the left DLPFC is promising for the rehabilitation of DOC patients, especially those in MCS. Further validation with a cohort of a larger sample size is required.

Retention of the spacing effect with mental practice in hemiparetic stroke.

Mental practice (MP) is a promising adjuvant to physical practice that involves many of the same mechanisms and takes on many of the same properties as physical practice. This study compared efficacy of a "massed" MP regimen versus a "distributed" MP regimen on upper extremity (UE) motor impairment and functional limitation. Twenty-seven chronic stroke survivors were administered the UE section of the Fugl-Meyer (FM) and Action Research Arm Test (ARAT), followed by standardized physical practice and MP regimens. One group was administered "massed" MP (60min of MP during a single daily session) and a second group administered distributed MP (20min of MP occurring three times/day). After intervention, changes in FM and ARAT scores of subjects in the distributed condition were significantly higher than those of subjects in the massed condition (FM 3.65, 95% CI 0.82-6.49, p value=0.01; ARAT 3.95, 95% CI 1.24-6.67, p value=0.006). Likewise, at POST 3, subjects in the distributed group showed significantly higher change in ARAT scores (ARAT 4.90, 95% CI 0.57-9.22, p value=0.03); the change in FM scores at POST 3 was 3.18 points higher among subjects in the distributed condition, but only approached significance (95% CI -1.27 to 7.63, p value=0.15). Results suggest that a distributed MP schedule is more efficacious in bringing about paretic UE changes than a massed practice schedule, especially in terms of reducing UE functional limitation.

The Effects of Different Repetitive Transcranial Magnetic Stimulation (rTMS) Protocols on Cortical Gene Expression in a Rat Model of Cerebral Ischemic-Reperfusion Injury.

Although repetitive Transcranial Magnetic Stimulation (rTMS) in treatment of stroke in humans has been explored over the past decade the data remain controversial in terms of optimal stimulation parameters and the mechanisms of rTMS long-term effects. This study aimed to explore the potential of different rTMS protocols to induce changes in gene expression in rat cortices after acute ischemic-reperfusion brain injury. The stroke was induced by middle cerebral artery occlusion (MCAO) with subsequent reperfusion. Changes in the expression of 96 genes were examined using low-density expression arrays after MCAO alone and after MCAO combined with 1Hz, 5Hz, continuous (cTBS) and intermittent (iTBS) theta-burst rTMS. rTMS over the lesioned hemisphere was given for two weeks (with a 2-day pause) in a single daily session and a total of 2400 pulses. MCAO alone induced significant upregulation in the expression of 44 genes and downregulation in 10. Two weeks of iTBS induced significant increase in the expression of 52 genes. There were no downregulated genes. 1Hz and 5Hz had no significant effects on gene expression, while cTBS effects were negligible. Upregulated genes included those involved in angiogenesis, inflammation, injury response and cellular repair, structural remodeling, neuroprotection, neurotransmission and neuronal plasticity. The results show that long-term rTMS in acute ischemic-reperfusion brain injury induces complex changes in gene expression that span multiple pathways, which generally promote the recovery. They also demonstrate that induced changes primarily depend on the rTMS frequency (1Hz and 5Hz vs. iTBS) and pattern (cTBS vs. iTBS). The results further underlines the premise that one of the benefits of rTMS application in stroke may be to prime the brain, enhancing its potential to cope with the injury and to rewire. This could further augment its potential to favorably respond to rehabilitation, and to restore some of the loss functions.

Sensory and sympathetic correlates of heat pain sensitization and habituation in men and women

Habituation and sensitization are important behavioural responses to repeated exposure to painful stimuli, but little is known about the factors determining sensory, affective and sympathetic habituation to repeated pain stimulation in men and women. Thirty volunteers (15 women) underwent a standardized heat pain paradigm spread over 8 consecutive days. At the beginning of the experiment, personality dimensions, coping strategies and pain catastrophizing thoughts were determined. Receiving a series of 10 blocks of six painful heat stimuli a day, participants rated pain intensity and unpleasantness. Skin conductance was recorded throughout the sessions. The results show similar habituation of both the sensory and affective dimensions of pain in men and women, although skin conductance did not undergo a significant decrease across the eight days. When focusing on single daily sessions, women showed pain sensitization but sympathetic habituation, while men showed pain sensitization but stable sympathetic activation. Our findings therefore indicate that the process of long-term habituation to painful heat stimuli is a common feature in both genders, whereas men and women might differently recruit their sympathetic nervous system for short-term pain processing. This study could potentially help to better evaluate gender-specific mechanisms in pain perception.

Comparison of the effect of multiple short-duration with single long-duration exercise sessions on glucose homeostasis in type 2 diabetes mellitus

We evaluated and compared the effects on glycaemic control of two different exercise protocols in elderly men with type 2 diabetes mellitus. Eighteen patients with type 2 diabetes mellitus carried out home-based bicycle training for 5 weeks. Patients were randomly assigned to one of two training programmes at 60% of maximal oxygen uptake: three 10 min sessions per day (3 x 10) or one 30 min session per day (1 x 30). Plasma insulin, C-peptide and glucose concentrations were measured during a 3 h oral glucose tolerance test (OGTT). Insulin sensitivity index (ISI(composite)), pre-hepatic insulin secretion rates (ISR) and change in insulin secretion per unit change in glucose concentrations (B(total)) were calculated. Cardiorespiratory fitness increased in response to training in both groups. In group 3 x 10 (n = 9) fasting plasma glucose (p = 0.01), 120 min glucose OGTT (p = 0.04) and plasma glucose concentration areas under the curve at 120 min (p < 0.04) and 180 min (p = 0.07) decreased. These parameters remained unchanged in group 1 x 30 (n = 9). No significant changes were found in ISI(composite), ISR and B(total) in either of the exercise groups. In a matched time-control group (n = 10), glycaemic control did not change. Moderate to high-intensity training performed at 3 x 10 min/day is preferable to 1 x 30 min/day with regard to effects on glycaemic control. This is in spite of the fact that cardiorespiratory fitness increased similarly in both exercise groups. A possible explanation is that the energy expenditure associated with multiple short daily sessions may be greater than that in a single daily session.

In-Hospital Short-term Training Program for Patients With Chronic Airway Obstruction

To compare the functional benefits and relative costs of administering an intense short-term inpatient vs a longer outpatient pulmonary rehabilitation program (PRP) for patients with chronic airway obstruction (CAO). Retrospective case-control study. Pulmonary ward and outpatient clinic of a rehabilitation center. Forty-three patients (case subjects) selected on the basis of selection criteria were compared with control subjects matched to them for age, sex, FEV(1), and diagnosis of either COPD or asthma. Case subjects performed 10 to 12 daily sessions (5 sessions a week) of inpatient PRP; control subjects performed 20 to 24 sessions (3 sessions a week) of outpatient PRP. At baseline and after the PRP, an incremental exercise test was performed, including evaluation of dyspnea and leg fatigue by Borg scale (D and F, respectively) at each workload step. The cost of PRP was also evaluated. Both PRPs resulted in similar significant improvements in cycloergometry peak workload (from 68 +/- 18 to 82 +/- 22 and from 75 +/- 17 to 87 +/- 27 W in case subjects and control subjects, respectively), isoload D (from 6.4 +/- 1.6 to 4.2 +/- 1.8 for case subjects and from 8.5 +/- 1.9 to 6.3 +/- 2.4 for control subjects) and isoload F (from 6.6 +/- 1.8 to 4.2 +/- 1.8 for case subjects and from 8.9 +/- 1.9 to 7.0 +/- 1.8 for control subjects). Although the single daily session was less expensive, the outpatient PRP total costs were greater because of the higher number of sessions and the cost of daily transportation. In patients with CAO, a shorter inpatient PRP may result in improvement in exercise tolerance similar to a longer outpatient PRP but with lower costs. Whether a shorter outpatient PRP may get physiologic and clinical benefits, while further reducing costs, must be evaluated by future controlled, randomized, prospective studies.

Breakpoint Determination and Ethanol Self‐Administration Using an Across‐Session Progressive Ratio Procedure in the Rat

Progressive ratio schedules are used to determine the "breakpoint" or limit to the amount of "work" that a subject is willing to perform to obtain a reinforcer. Reinforcing efficacy is inferred from the breakpoint values, which are typically measured in a single session by increasing the number of responses required for successive reinforcer presentations. This procedure is not feasible, however, when assessing the reinforcing efficacy of a substance that can change as a function of its physiological actions during self-administration, as in the case of ethanol. The present study made use of a procedure that increased the response requirement across single daily sessions rather than within a session. Completion of the response requirement in each daily session resulted in the presentation of a drinking tube that allowed for self-administration of ethanol for a 20-min period. This procedure made possible the assessment of ethanol-directed appetitive (number of lever presses) and consummatory (number of licks and intake volume) behaviors. Reliable responding for 10% ethanol was initiated using sucrose-substitution on a fixed ratio (FR) 4 schedule in male Long Evans rats. Then four successive breakpoint determinations were made which were separated by a return to the FR4 schedule to re-establish baseline responding. The results indicated that there was an increase in breakpoint values from the first to the second determination, which was then stable over the following three determinations. Individual rats reached breakpoints as high as 240 lever presses to receive access to 10% ethanol and maintained ethanol intake over sessions in the 1.0 g/kg range. Ethanol intake (g/kg), however, was stable across all four determinations (mean 0.86 +/- 0.06 to 1.01 +/- 0.10). Moreover, ethanol intake was not related to the preceding appetitive responding, as no differences between intake on the session before a breakpoint (high FR) and the following baseline period (FR4) were observed. This model provides an assessment of the distinct mechanisms that mediate ethanol-seeking versus ethanol consumption in subjects that drink measurable amounts of ethanol, with the appetitive behaviors not altered by the pharmacological effects of ethanol.

Efficient conditioned inhibition of the rabbit’s nictitating membrane response with massed training

Using a light (L) as the reinforced CS and a tone (T) as the conditioned inhibitor, rabbits received conditioned inhibition (CI) training of the nictitating membrane response. In Experiment 1, animals were matched in terms of initial acquisition to L and T, using electric shock to the eye as the UCS to form three groups. Group 100 received 100 CI trials per single daily session, Group 200 received 200 CI trials per single daily session, and Group 100/100 received 200 daily trials in two sessions separated by an interval of approximately 3 h. Each unit of 100 trials consisted of 50 reinforced L trials (L+) and 50 nonreinforced L-T compound trials (LT-). The development of suppressed conditioned responding over the course of 1,300 CI trials and the results of a retardation test (T+) failed to detect differences among these three trials-distribution procedures. Experiment 2 examined the development of CI using the two-session/day procedure with intersession intervals of 3 and 6 h. No differences in CI were apparent over the course of 2,000 trials or in the retardation test. These findings suggest robust CI can be obtained with relatively massed training and that theories of CI might minimize the role of distribution of training in their formulations.