Untrained Adults Research Articles

Resistance Training Using VAriable Resistance Suit (VARS) Increased Isometric and Isokinetic Muscle Strength.

While resistance training promotes muscle hypertrophy and strength, accessibility of equipment is a barrier. This study evaluated a wearable VAriable Resistance Suit (VARS) as a novel and alternative method to achieve muscle strength improvement. It was hypothesized that by providing adjustable, bi-directional and speed dependent resistance, VARS can target specific muscles to improve muscle strength via an accessible and portable device. Twelve untrained healthy male adults (22.08 ± 4.1 years old) participated in an 8-week long resistance training using VARS to strengthen four muscles (biceps brachii, triceps brachii, biceps femoris, rectus femoris) of their non-dominant arm and leg using VARS. The results showed significant improvements in the muscle strength measured by isokinetic dynamometer - 49.9±9.6% increase in isokinetic force and 30.6±7.6% increase in isometric force. Muscle size and body composition were also assessed using ultrasound imaging and bioelectrical impedance analysis, which did not show significant changes. The study demonstrates the efficacy and feasibility of VARS as a resistance training tool to achieve muscle strength improvement and its potential extension to clinical populations.

The Effects of Suspension Training on Dynamic, Static Balance, and Stability: An Interventional Study.

Background and Objectives: While suspension training devices are increasingly gaining popularity, there is limited evidence on their effects on balance, and no comprehensive assessment has been conducted. This study aimed to evaluate the effects of a 9-session suspension training program on dynamic and static balance, stability, and functional performance. Materials and Methods: A total of forty-eight healthy adults, aged between 18 and 30, participated in a 9-session suspension training program. The program included exercises targeting upper and lower body muscles as well as core muscles. Balance was comprehensively assessed using various dynamic balance tests, including the Y Balance Test (YBT) as the primary outcome, single-leg Emery test, and sideways jumping test. Static balance was evaluated through the monopedal and bipedal Romberg tests. Changes from baseline were analyzed using a one-way ANOVA test. Results: Thirty-nine participants (mean age: 21.8 years) completed the intervention. The intervention resulted in significant improvements in YBT, jumping sideways, Emery, and 30s-SST scores (p < 0.001). Platform measures indicated enhanced monopedal stability (p < 0.001) but did not show a significant effect on bipedal stability (p > 0.05). Conclusions: Suspension training is a safe and feasible method for improving dynamic balance and functional performance in healthy, untrained young adults. However, it does not appear to significantly impact the ability to maintain a static posture while standing.

МОРФОЛОШКЕ И ФУНКЦИОНАЛНЕ КАТАКТЕРИСТИКЕ ДЕСНОГ СРЦА КОД ЕЛИТНИХ ТРИАТЛОНАЦА ИЗ СРБИЈЕ

Many research papers show that the most intense cardiac remodelling can be seen in endurance athletes, but no studies have examined right heart remodelling in triathletes. The aim of the study is to examine the morphological and functional characteristics of the right heart in elite Serbian triathletes. To assess the morpho-functional characteristics of the right heart, cardiac ultrasounds were performed following current recommendations, using a Philips IE33 device and a 5.2-MHz probe. The right ventricular diameter (RVEDD) was measured from the parasternal cross-section, and the right atrial volume (RAvol) and the right ventricular wall thickness (RVWT) were measured from the four-cavity cross-section. The M-mode method was used to measure the amplitude of the movement of the right ventricular tricuspid annulus (TAPSE). The sample consisted of two groups of men: experimental – elite triathlete seniors from Serbia (n=17; age: 35.88±11.27), and control – healthy untrained adults (n=20; age: 21.35±2.08). RVEDD, RAvol, and RVWT were significantly higher in the experimental group compared to the control group (p&lt;0.01), but no significant difference was observed in TAPSE (p=0.653). Also, RVEDD and RAvol in the experimental group showed values higher than the reference values for the general population, while RVWT and TAPSE were within reference values. The obtained results indicate that there are signs of right heart remodeling in triathletes. Considering the growing number of persons involved in triathlon, it is necessary to draw the attention of all coaches and athletes to the importance of regularly monitoring the triathletes’ hearts.

Triceps surae muscle hypertrophy is greater after standing versus seated calf-raise training.

Background: The triceps surae muscle plays important roles in fundamental human movements. However, this muscle is relatively unresponsive to resistance training (difficult to hypertrophy) but prone to atrophy with inactivity compared with other muscles. Thus, identifying an effective training modality for the triceps surae is warranted. This study compared triceps surae muscle hypertrophy after standing/knee-extended versus seated/knee-flexed plantarflexion (calf-raise) training, where the gastrocnemius is lengthened and shortened, respectively. Methods: Fourteen untrained adults conducted calf-raise training with one leg in a standing/knee-extended position and the other leg in a seated/knee 90°-flexed position at 70% of one-repetition maximum. Each leg performed 10 repetitions/set, 5 sets/session, 2 sessions/week for 12weeks. Before and after the intervention, magnetic resonance imaging scans were obtained to assess muscle volume of each and the whole triceps surae. Results: Muscle volume significantly increased in all three muscles and the whole triceps surae for both legs (p ≤ 0.031), except for the gastrocnemius muscles of the seated condition leg (p = 0.147-0.508). The changes in muscle volume were significantly greater for the standing than seated condition leg in the lateral gastrocnemius (12.4% vs. 1.7%), medial gastrocnemius (9.2% vs. 0.6%), and whole triceps surae (5.6% vs. 2.1%) (p ≤ 0.011), but similar between legs in the soleus (2.1% vs. 2.9%, p = 0.410). Conclusion: Standing calf-raise was by far more effective, therefore recommended, than seated calf-raise for inducing muscle hypertrophy of the gastrocnemius and consequently the whole triceps surae. This result and similar between-condition hypertrophy in the soleus collectively suggest that training at long muscle lengths promotes muscle hypertrophy.

Endocannabinoid and psychological responses to acute resistance exercise in trained and untrained adults.

This study examined the effects of acute resistance exercise on circulating endocannabinoid (eCB) and mood responses in trained and untrained healthy adults. Thirty-two healthy adults (22.1 ± 2.9 years) were recruited from trained (reporting resistance exercise at least twice per week for ≥ previous three months) and untrained (performing no resistance exercise for ≥ previous three months) groups. Participants (13 male, 19 female) completed three sets of resistance exercise (16 repetitions at 50% 1-repetition max, 12 repetitions at 70% 1-repetition max, 8 repetitions at 80% 1-repetition max). Resistance machines targeted the legs, chest, back, and abdominal muscles. Mood states, affect, and circulating eCB concentrations were evaluated before and after resistance exercise. There were significant decreases in AEA, PEA, and OEA levels following acute resistance exercise (p <0.05; ds = -0.39, -0.48, -0.65, respectively), with no significant group differences or group by time interactions. 2-AG did not change significantly. Positive affect increased significantly following resistance exercise (p = 0.009), while negative affect decreased (p <0.001). Depressive symptoms, anger, confusion, and total mood disturbance decreased significantly (p <0.05), while vigor increased significantly following resistance exercise (p = 0.005). There were no significant group differences or group by time interactions for any psychological outcomes. These results indicate that acute resistance exercise may reduce eCB and related lipid concentrations, which is opposite to the increase in lipids typically observed with acute aerobic exercise. Furthermore, psychological improvements occur after resistance exercise regardless of decreases in eCBs, supporting the notion that psychological changes with exercise likely occur through a wide variety of biological and environmental mechanisms.

Effect of Moderate Versus Vigorous Exercise Intensity on Body Composition in Young Untrained Adults: The Activating Brown Adipose Tissue Through Exercise (ACTIBATE) Randomized Controlled Trial.

The present study aimed to investigate the effect of a 24-week aerobic + resistance training programs at moderate versus vigorous intensity on body composition, and the persistence of the changes after a 10-month free-living period, in young untrained adults. This report is based on a secondary analysis from the activating brown adipose tissue through exercise (ACTIBATE) single-center unblinded randomized controlled trial. A total of 144 young adults (65.6% women) aged 18-25years were randomly allocated to three different groups: (a)aerobic + resistance exercise training program based on the international physical activity recommendations at vigorous intensity (Ex-Vigorous group), (b)at moderate intensity (Ex-Moderate group), and (c)control group (no exercise). Body composition outcomes were determined by a dual-energy X-ray absorptiometry scanner. Both Ex-Vigorous and Ex-Moderate decreased body weight, fat mass, and visceral adipose tissue mass in a similar manner (all p < .04). After a 10-month free-living period, these parameters returned to baseline levels in both exercise groups (all ps < .03). No differences between the exercise groups and the control group were noted in lean mass changes (all ps > .1). A 24-week aerobic + resistance training intervention based on the international physical activity recommendations was enough to improve body weight, fat mass, and visceral adipose tissue mass in untrained young adults, independently of the exercise intensity (moderate vs. vigorous).

Endocannabinoid Responses To Acute Resistance Exercise In Trained And Untrained Adults

Endocannabinoid Responses To Acute Resistance Exercise In Trained And Untrained Adults

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.

Rhodiola rosea as an adaptogen to enhance exercise performance: a review of the literature.

Rhodiola rosea (RR) is a plant whose bioactive components may function as adaptogens, thereby increasing resistance to stress and improving overall resilience. Some of these effects may influence exercise performance and adaptations. Based on studies of rodents, potential mechanisms for the ergogenic effects of RR include modulation of energy substrate stores and use, reductions in fatigue and muscle damage and altered antioxidant activity. At least sixteen investigations in humans have explored the potential ergogenicity of RR. These studies indicate acute RR supplementation (∼200 mg RR containing ∼1 % salidroside and ∼3 % rosavin, provided 60 min before exercise) may prolong time-to-exhaustion and improve time trial performance in recreationally active males and females, with limited documented benefits of chronic supplementation. Recent trials providing higher doses (∼1500 to 2400 mg RR/d for 4–30 d) have demonstrated ergogenic effects during sprints on bicycle ergometers and resistance training in trained and untrained adults. The effects of RR on muscle damage, inflammation, energy system modulation, antioxidant activity and perceived exertion are presently equivocal. Collectively, it appears that adequately dosed RR enhances dimensions of exercise performance and related outcomes for select tasks. However, the current literature does not unanimously show that RR is ergogenic. Variability in supplementation dose and duration, concentration of bioactive compounds, participant characteristics, exercise tests and statistical considerations may help explain these disparate findings. Future research should build on the longstanding use of RR and contemporary clinical trials to establish the conditions in which supplementation facilitates exercise performance and adaptations.

Effects of a 10-week musical instrument training on cognitive function in healthy older adults: implications for desirable tests and period of training.

Previous studies have shown that musical instrument training programs of 16 or more weeks improve verbal memory (Logical Memory Test delayed recall), processing speed (Digit Symbol Coding Test), and executive function (Trail Making Test Part B) of musically untrained healthy older adults. However, it is unclear whether shorter-period instrument training can yield similar effects. We sought to (1) verify those results and (2) clarify if intervention effects could be detected using other measures such as reaction time. Healthy older adults (mean age = 73.28 years) were pseudo-randomly assigned to an untrained control group (n = 30) or an intervention group (n = 30) that received a weekly 10-session musical instrument training program (using melodica). We conducted neuropsychological tests on which intervention effects or association with musical training were reported in previous studies. We newly included two reaction time tasks to assess verbal working memory (Sternberg task) and rhythm entrainment (timing task). Intervention effects were determined using a "group × time" analysis of variance (ANOVA). The intervention effects were detected on the reaction time in Sternberg task and phonological verbal fluency. Although intervention effects had been reported on Logical Memory test, Digit Symbol Coding Test and Trail Making Test in previous studies with longer training periods, the present study did not show such effects. Instead, the test-retest practice effect, indicated by significant improvement in the control group, was significant on these tests. The present results indicated the usefulness of working memory assessments (Verbal Fluency Test and Sternberg task) in detecting the effects of short-term melodica training in healthy older adults. The practice effect detected on those three tasks may be due to the shorter interval between pre- and post-intervention assessments and may have obscured intervention effects. Additionally, the findings suggested the requirement for an extended interval between pre- and post-tests to capture rigorous intervention effects, although this should be justified by a manipulation of training period.

The relevance of body composition assessment for the rating of perceived exertion in trained and untrained women and men.

Introduction: Mechanic power output (MPO) and oxygen consumption (VO2) reflect endurance capacity and are often stated relative to body mass (BM) but less often per skeletal muscle mass (SMM). Rating of perceived exertion (RPE) has previously shown conflicting results between sexes at submaximal intensities. Individual body composition, however, largely differs due to sex and training status. It was the aim of this study to evaluate RPE of untrained and trained individuals of both sexes considering body composition and to estimate whether RPE could be improved as a tool to determine endurance capacity. Methods: The study included 34 untrained adults (age 26.18 ± 6.34years, 18 women) and 29 endurance trained (age 27.86 ± 5.19, 14 women) who were measured for body composition (InBody 770, InBody Europe B.V., Germany) and tested on a treadmill (Pulsar, H/P/Cosmos, Germany) for aerobic capacity (Metalyzer 3B, Cortex Biophysik GmbH, Germany) in an all-out exercise test applying the Bruce-protocol. VO2, MPO, heart rate (HR), and RPE were obtained at each exercise stage. VO2 and MPO were calculated per BM and SMM. RPE values were correlated with absolute VO2 and MPO, as well as relative to BM, and SMM. HR values and the parameters' standardized values served for comparison to standard procedures. Results: VO2 and MPO were higher in men compared to women and in trained compared to untrained participants. No differences between groups and sexes exist when VO2 and MPO were calculated per BM. When calculated per SMM, VO2 and MPO indicate opposite results already at low intensity stages of exercise test. RPE values had highest correlation with MPO per SMM (R2 = 0.8345) compared to absolute MPO (R2 = 0.7609), or MPO per BM (R2 = 0.8176). Agreement between RPE and MPO per SMM was greater than between RPE and HR (p = 0.008). Conclusion: Although RPE represents a subjective value at first glance, it was shown that RPE constitutes a valuable tool to estimate endurance capacity, which can be further enhanced if individual body composition is considered. Furthermore, MPO and VO2 should be considered relative to SMM. These findings might help to avoid over-exertion, especially among untrained people, by adjusting the training intensity for each subject according to the individual strain evaluated in an exercise test based on individual body composition.

Blueberry intake elevates post-exercise anti-inflammatory oxylipins: a randomized trial

This study determined if 18 days of supplementation with blueberries (BL) compared to placebo (PL) could mitigate muscle soreness and damage and improve inflammation resolution in untrained adults (n = 49, ages 18–50 years) after engaging in a 90-min bout of “weekend warrior” eccentric exercise. The BL freeze dried supplement provided 1 cup of fresh blueberries per day equivalent with 805 mg/day total phenolics and 280 mg/day anthocyanins. Urine levels of eight BL gut-derived phenolics increased after 14- and 18-days supplementation with 83% higher concentrations in BL vs. PL (p < 0.001). The 90-min exercise bout caused significant muscle soreness and damage during 4d of recovery and a decrease in exercise performance with no significant differences between PL and BL. Plasma oxylipins were identified (n = 76) and grouped by fatty acid substrates and enzyme systems. Linoleic acid (LA) oxylipins generated from cytochrome P450 (CYP) (9,10-, 12,13-dihydroxy-9Z-octadecenoic acids) (diHOMEs) were lower in BL vs. PL (treatment effect, p = 0.051). A compositive variable of 9 plasma hydroxydocosahexaenoic acids (HDoHEs) generated from docosahexaenoic acid (DHA, 22:6) and lipoxygenase (LOX) was significantly higher in BL vs. PL (treatment effect, p = 0.008). The composite variable of plasma 14-HDoHE, 17-HDoHE, and the eicosapentaenoic acid (EPA)-derived oxylipin 18-hydroxyeicosapentaenoic acid (18-HEPE) (specialized pro-resolving lipid mediators, SPM, intermediates) was significantly higher in BL vs PL (treatment effect, p = 0.014). Pearson correlations showed positive relationships between post-exercise DHA-LOX HDoHEs and SPM intermediates with urine blueberry gut-derived phenolics (r = 0.324, p = 0.023, and r = 0.349, p = 0.015, respectively). These data indicate that 18d intake of 1 cup/day blueberries compared to PL was linked to a reduction in pro-inflammatory diHOMES and sustained elevations in DHA- and EPA-derived anti-inflammatory oxylipins in response to a 90-min bout of unaccustomed exercise by untrained adults.

#5621 BENEFICIAL EFFECTS OF CHRONIC INTRADIALYTIC EXERCISE TRAINING ON HEMODIALYSIS-INDUCED-MYOCARDIAL STUNNING

Abstract Background and Aims Hemodialysis (HD) induces left ventricular (LV) segmental regional wall motion abnormalities (RWMAs) due to hypoperfusion, leading to acute LV transient dysfunction, well known as myocardial stunning. Repeated episodes of HD-related myocardial stunning contribute directly to the development of heart failure and increased mortality in patients receiving HD (Burton et al., 2009). Exercise training exert pleiotropic favorable effects on the cardiovascular system. No study has however investigated its impact on the kinetics of regional myocardial function during HD. This study aims to evaluate the effect of intradialytic exercise (IDE) on RWMAs compared with standard care. Method This was a prospective, open-label, two-center trial (clinicaltrials.gov NCT04697459) with two parallel groups: 31 patients (ENT) undergoing a 4-month IDE program (30min of cycling + 30min of resistance training starting 30 min after HD onset) and 21 patients continuing usual care (CTRL). Untrained adults, aged 20-79 years, undertaking maintenance HD for &amp;gt;3 months were eligible to participate. Exclusion criteria were poor echogenicity, contraindication to exercise, orthopedic complications, severe heart (ischemic, valvular, ...), vascular or respiratory diseases, ejection fraction &amp;lt;45% and body mass index &amp;gt;35. Longitudinal strain (LS) using speckle-tracking echocardiography were measured during a standard HD session, just before HD onset (HDT0) and at peak stress of HD (30 min before HD-ending, HDPeak). The same procedure was used before and after 4-months of IDE or usual care. LS from a 18 LV segment model were used to assess the presence of HD-induced RWMAs, defined as a ≥20% reduction in LS at peak stress compared to baseline. A generalized linear mixed model (Poisson model) was used to analyze the effect of IDE on RWMAs. Results After 4 months of IDE, we observed a significant reduction of RWMAs at HDPeak (mean before: 6.03±3.19 vs after: 4.55±2.26; point estimate: -1.48, 95% confident interval CI: -0.39/-2.57, p = 0.03), whereas its occurrence remained unchanged in CTRL (mean before: 6.14±3.51 vs after: 6.09±3.16; point estimate: -0.05; 95% CI: 1.45/-1.54, p = 0.96). There was also evidence that IDE program significantly attenuated the decline of global LS observed during HD (before: 2.11±2.39% vs after: 1.10±1.95%; point estimate: -1.01%; 95% CI: -1.86/-0.13, p = 0.02) compared to the similar impairment in CTRL (before: 1.60±2.30% vs after: 1.79±2.08%; point estimate: +0.18%; 95% CI: +1.20/-0.85 p = 0.72). Conclusion There is clear evidence that chronic IDE is cardioprotective. Identifying the underlying mechanisms responsible for exercise-induced cardioprotection was beyond the scope of our study, but we can reasonably assume that structural and/or functional changes in the coronary arteries, especially in microcirculatory territories (i.e. increased collateral circulation due to angiogenesis/arteriogenesis, improved endothelial function, reduced blood viscosity) and/or intrinsic changes in the cardiac myocyte (reduced fibrosis, enhanced calcium handling/sensitivity, altered mitochondrial turnover and phenotype), related among others to reduced oxidative stress and/or inflammation, might play a role (Powers et al 2014). Whether our results translate to longer-term reduction in clinical outcomes and cardiovascular mortality in end-stage renal disease patients require further studies.

Myoelectric activity and improvements in strength and hypertrophy are unaffected by the ankle position during prone leg curl exercise – a within person randomized trial

ABSTRACT To examine the effect of ankle position (i.e. gastrocnemius muscle length) on training outcomes during leg curl exercise, we recruited untrained and trained healthy adults to participate in two separate experiments. In Experiment 1, we studied the acute influence of ankle position on knee flexor myoelectric (EMG) activity during leg curl exercise in a group of trained and a separate group of untrained adults. In Experiment 2, we studied the effects of ankle position on knee flexors muscle thickness and torque across a 10-week training protocol in trained adults. We hypothesized that leg curl exercise with the ankle in a plantarflexed position would enhance EMG activity, muscular strength, and hamstrings muscle thickness. We randomized the legs within a person to perform leg curl exercise with one in a plantarflexed position and the other in a dorsiflexed position. Experiment 1 revealed no significant differences between ankle positions in the EMG activity of hamstring muscle in either group (all p > 0.05). Experiment 2 revealed a significant pre- to post-intervention increase in biceps femoris long head (BFLH) muscle thickness (p = 0.026) and isometric torque (p = 0.03), but there were no significant effects of the ankle position (p = 0.596) or interaction between ankle position and timepoint for these variables (p = 0.420). In sum, the ankle position did not have acute effects on hamstrings EMG activity, nor did it affect strength and hypertrophy adaptations after 10-weeks of leg curl exercise training. Interestingly, however, the limb which performed leg curl exercise in a dorsiflexed position performed a higher total training volume. Highlights Different ankle positions (i.e. dorsiflexion or plantarflexion) do not affect hamstrings EMG activity during prone leg curl exercise. Different ankle positions show similar adaptation in strength and hypertrophy of biceps femoris long head after 10 weeks of training. Training in the plantarflexed position may be useful for time-constrained individuals, allowing similar training adaptations with smaller training volume.

Equalization of the Occlusal State by Wearing a Mouthguard Contributes to Improving Postural Control Function

The aim of this study was to clarify the effect on the postural control function of equalizing the occlusal contact state by wearing a mouthguard. Method: Participants included 23 untrained adults, 11 gymnasts, and 10 weightlifters. Custom mouthguards were fabricated and adjusted so that all teeth were in even contact with light clenching. The standing postural control function was evaluated by the displacement of the center of foot pressure (COP) measured using a gravity center fluctuation meter. Measurement conditions were with and without a mouthguard. Statistical analyses were performed on the differences in COP displacement among participant groups and between mouthguard conditions and the difference in the reduction rate of COP displacement when wearing a mouthguard among participant groups. Results: COP significantly decreased in the order of untrained adults to weightlifters to gymnasts, irrespective of the mouthguard condition. The reduction rate in COP displacement after wearing a mouthguard was greatest in gymnasts. Conclusions: The effect of the mouthguard on postural control function was more pronounced in gymnasts than in untrained adults and weightlifters, and this study suggests that equalization of the occlusal state by wearing a mouthguard contributes to improving postural control function.

When Naïve Pedagogy Breaks Down: Adults Rationally Decide How to Teach,but Misrepresent Learners' Beliefs.

From early in childhood, humans exhibit sophisticated intuitions about how to share knowledge efficiently in simple controlled studies. Yet, untrained adults often fail to teach effectively in real-world situations. Here, we explored what causes adults to struggle in informal pedagogical exchanges. In Experiment 1, we first showed evidence of this effect, finding that adult participants failed to communicate their knowledge to naïve learners in a simple teaching task, despite reporting high confidence that they taught effectively. Using a computational model of rational teaching, we found that adults assigned to our teaching condition provided highly informative examples but failed to teach effectively because their examples were tailored to learners who were only considering a small set of possible explanations. In Experiment 2, we then found experimental evidence for this possibility, showing that knowledgeable participants systematically misunderstand the beliefs of naïve participants. Specifically, knowledgeable participants assumed naïve agents would primarily consider hypotheses close to the correct one. Finally, in Experiment 3, we aligned learners' beliefs to knowledgeable agents' expectations and showed learners the same examples selected by participants assigned to teach in Experiment 1. We found that these same examples were significantly more informative once learners' hypothesis spaces were constrained to match teachers' expectations. Our findings show that, in informal settings, adult pedagogical failures result from an inaccurate representation of what naïve learners believe is plausible and not an inability to select informative data in a rational way.

Molecular predictors of resistance training outcomes in young untrained female adults.

We sought to determine if the myofibrillar protein synthetic (MyoPS) response to a naïve resistance exercise (RE) bout, or chronic changes in satellite cell number and muscle ribosome content, were associated with hypertrophic outcomes in females or differed in those who classified as higher (HR) or lower (LR) responders to resistance training (RT). Thirty-four untrained college-aged females (23.4 ± 3.4 kg/m2) completed a 10-wk RT protocol (twice weekly). Body composition and leg imaging assessments, a right leg vastus lateralis biopsy, and strength testing occurred before and following the intervention. A composite score, which included changes in whole body lean/soft tissue mass (LSTM), vastus lateralis (VL) muscle cross-sectional area (mCSA), midthigh mCSA, and deadlift strength, was used to delineate upper and lower HR (n = 8) and LR (n = 8) quartiles. In all participants, training significantly (P < 0.05) increased LSTM, VL mCSA, midthigh mCSA, deadlift strength, mean muscle fiber cross-sectional area, satellite cell abundance, and myonuclear number. Increases in LSTM (P < 0.001), VL mCSA (P < 0.001), midthigh mCSA (P < 0.001), and deadlift strength (P = 0.001) were greater in HR vs. LR. The first-bout 24-hour MyoPS response was similar between HR and LR (P = 0.367). While no significant responder × time interaction existed for muscle total RNA concentrations (i.e., ribosome content) (P = 0.888), satellite cell abundance increased in HR (P = 0.026) but not LR (P = 0.628). Pretraining LSTM (P = 0.010), VL mCSA (P = 0.028), and midthigh mCSA (P < 0.001) were also greater in HR vs. LR. Female participants with an enhanced satellite cell response to RT, and more muscle mass before RT, exhibited favorable resistance training adaptations.NEW & NOTEWORTHY This study continues to delineate muscle biology differences between lower and higher responders to resistance training and is unique in that a female population was interrogated. As has been reported in prior studies, increases in satellite cell numbers are related to positive responses to resistance training. Satellite cell responsivity, rather than changes in muscle ribosome content per milligrams of tissue, may be a more important factor in delineating resistance-training responses in women.

Almond intake alters the acute plasma dihydroxy-octadecenoic acid (DiHOME) response to eccentric exercise.

This investigation determined if 4-weeks ingestion of nutrient-dense almonds mitigated post-exercise inflammation and muscle soreness and damage. An acute 90-min of eccentric exercise (90-EE) was used to induce muscle damage in 64 non-obese adults not engaging in regular resistance training (ages 30-65 years, BMI < 30 kg/m2). Using a parallel group design, participants were randomized to almond (AL) (57 g/d) or cereal bar (CB) (calorie matched) treatment groups for a 4-week period prior to the 90-EE (17 exercises). Blood and 24-h urine samples were collected before and after supplementation, with additional blood samples collected immediately post-90-EE, and then daily during 4 additional days of recovery. Changes in plasma oxylipins, urinary gut-derived phenolics, plasma cytokines, muscle damage biomarkers, mood states, and exercise performance were assessed. The 90-EE protocol induced significant muscle damage, delayed onset of muscle soreness (DOMS), inflammation, reduced strength and power performance, and mood disturbance. Interaction effects (2 group × 7 time points) supported that AL vs. CB was associated with reduced post-exercise fatigue and tension (p = 0.051, 0.033, respectively) and higher levels of leg-back strength (p = 0.029). No group differences were found for post-90-EE increases in DOMS and six cytokines. AL was associated with lower levels of serum creatine kinase immediately- and 1-day post-exercise (p = 0.034 and 0.013, respectively). The 90-EE bout increased plasma levels immediately post-exercise for 13 oxylipins. Interaction effects revealed significantly higher levels for AL vs. CB for 12,13-DiHOME (p < 0.001) and lower levels for 9,10-DiHOME (p < 0.001). Urine levels increased in AL vs. CB for seven gut-derived phenolics including 5-(3',4'-dihydroxyphenyl)-γ-valerolactone that was inversely related to changes in plasma 9,10-DiHOME (r = -0.029, p = 0.021). These data support some positive effects of almond intake in improving mood state, retaining strength, decreasing muscle damage, increasing the generation of gut-derived phenolic metabolites, and altering the plasma oxylipin DiHOME response to unaccustomed eccentric exercise in untrained adults. The elevated post-exercise plasma levels of 12,13-DiHOME with almond intake support positive metabolic outcomes for adults engaging in unaccustomed eccentric exercise bouts.

Acute resistance exercise training does not augment mitochondrial remodelling in master athletes or untrained older adults.

Background: Ageing is associated with alterations to skeletal muscle oxidative metabolism that may be influenced by physical activity status, although the mechanisms underlying these changes have not been unraveled. Similarly, the effect of resistance exercise training (RET) on skeletal muscle mitochondrial regulation is unclear. Methods: Seven endurance-trained masters athletes ([MA], 74 ± 3years) and seven untrained older adults ([OC]. 69 ± 6years) completed a single session of knee extension RET (6 x 12 repetitions, 75% 1-RM, 120-s intra-set recovery). Vastus lateralis muscle biopsies were collected pre-RET, 1h post-RET, and 48h post-RET. Skeletal muscle biopsies were analyzed for citrate synthase (CS) enzyme activity, mitochondrial content, and markers of mitochondrial quality control via immunoblotting. Results: Pre-RET CS activity and protein content were ∼45% (p < .001) and ∼74% greater in MA compared with OC (p = .006). There was a significant reduction (∼18%) in CS activity 48h post-RET (p < .05) in OC, but not MA. Pre-RET abundance of individual and combined mitochondrial electron transport chain (ETC) complexes I-V were significantly greater in MA compared with OC, as were markers of mitochondrial fission and fusion dynamics (p-DRP-1Ser616, p-MFFSer146, OPA-1 & FIS-1, p < .05 for all). Moreover, MA displayed greater expression of p-AMPKThr172, PGC1α, TFAM, and SIRT-3 (p < .05 for all). Notably, RET did not alter the expression of any marker of mitochondrial content, biogenesis, or quality control in both OC and MA. Conclusion: The present data suggest that long-term aerobic exercise training supports superior skeletal muscle mitochondrial density and protein content into later life, which may be regulated by greater mitochondrial quality control mechanisms and supported via superior fission-fusion dynamics. However, a single session of RET is unable to induce mitochondrial remodelling in the acute (1h post-RET) and delayed (48h post-RET) recovery period in OC and MA.

Intensity of arm swing exercise with music-movement synchrony in untrained young adults

IntroductionThe research aimed to study the intensity of arm swing exercise (ASE) with different tempi of music-movement synchrony in untrained young adults and to investigate the effect of different music tempi on heart rate and oxygen consumption.MethodsParticipants were 30 healthy volunteers (15 males and 15 females), 20.67 ± 1.37 years and low-to-moderate physical activity. They performed ASE synchronised with music at a tempo of 60 and 140 bpm with a random sequence. They were measured for heart rate and oxygen consumption using a Quark SPIRO (COSMED) before and after the ASE for 6 minutes of each tempo. They rested for at least 15 minutes between music tempi during the ASE. The intensity of ASE with music-movement synchrony of each tempo was calculated as a percentage of maximum heart rate (%HRmax) and percentage maximum oxygen consumption (%VO&lt;sub&gt;2max&lt;/sub&gt;).ResultsThe %HRmax of all participants post-ASE at 60 and 140 bpm were 58.64 ± 8.82 and 60.12 ± 8.95%, respectively. The %VO&lt;sub&gt;2max&lt;/sub&gt; of all participants post-ASE at 60 and 140 bpm were 38.65 ± 11.36 and 40.17 ± 10.71%, respectively. There was no significant difference in HR and VO2 of ASE between music tempi.ConclusionsThe ASE with music-movement synchrony at 60 and 140 bpm is a low-intensity aerobic exercise, so is a suitable choice for people with low physical activity. Furthermore, the faster tempo did not significantly alter the intensity, therefore, we recommend selecting the slower music tempo at 60 bpm to avoid repetitive shoulder joint injury.