Effects of lunges inserted in walking (eccentric walking) on lower limb muscle strength, physical and cognitive function of regular walkers.

INTRODUCTION: Walking is a popular exercise but does not increase lower limb muscle strength and balance. We hypothesized that muscle strength, physical and cognitive function would be improved by inserting lunges in conventional walking. METHODS: Eleven regular walkers (54-88 years) who had more than 5000 steps in exercise walking a day at least 5 days a week participated in this study. They walked as usual for the first 4 weeks and included lunges and descending stairs or slope walking (i.e., eccentric walking) for the next 8 weeks. The steps of eccentric walking were gradually increased from 100 to 1000 steps per week over 8 weeks. RESULTS: The average steps per day were 10,535 ± 3516 in the first 4 weeks, and 10,118 ± 3199 in the eccentric walking period without a significant difference. No significant changes in maximal voluntary isometric contraction torque of the knee extensors (MVC), 30-s chair stand (CS), 2-min step, balance assessed by center of pressure movement area with eyes close, sit and reach, a digit symbol substitution test (DSST) for cognitive function were observed in the first 4 weeks. However, significant (P < 0.05) improvements were evident in MVC (18.6 ± 15.7%), CS (24.2 ± 17.3%), balance ( - 45.3 ± 34.5%), and DSST (20.8 ± 16.7%) from weeks 4 to 12. Serum complement component 1q concentration decreased (P < 0.05) from weeks 4 to 12, although no changes in serum glucose, triglyceride, and cholesterol concentrations were observed. CONCLUSION: These results supported the hypothesis, and suggest that eccentric walking provides effects that are not achieved by conventional walking.

Eccentric-only versus concentric-only resistance training effects on biochemical and physiological parameters in patients with type 2 diabetes.

BACKGROUND: The benefits of resistance training for patients with type 2 diabetes (T2D) are well documented; however, the effects of exercise with different muscle contraction types such as eccentric versus concentric contractions on physiological outcomes for this population are not clear. This study compared eccentric-only (ECC) and concentric-only resistance training (CON) to test the hypothesis that ECC would be superior to CON to improve insulin sensitivity, lipid profile, body composition, muscle strength and physical function of patients with T2D. METHODS: Adults with T2D (50-79 years) were allocated to the ECC (n = 9) or CON group (n = 9). Resistance exercises (chest press, lateral pulldown, bicep curl, triceps extension, leg extension, leg curl, calf raise, abdominal crunch) consisting of 2-3 sets of 10 eccentric-only (5 s) or concentric-only contractions (1-2 s) was performed twice a week for 12 weeks. Changes in blood biomarkers, body composition, muscle strength and physical function from pre- to post-intervention were compared between groups. RESULTS: Overall rating of perceived exertion (RPE, 1-10 Borg scale) was lower (p < 0.05) for ECC (2.9 ± 1.2) than CON (5.4 ± 1.1). No significant changes in blood biomarkers were found for both groups. Lean mass increased [effect size (ES) = 0.148, ECC 3.2 ± 6.9%; CON 3.6 ± 2.3%], and fat mass decreased (ES = 0.545, ECC - 6.1 ± 12.4%; CON - 7.1 ± 16.4%) (p < 0.05) similarly. One-repetition maximal strength of each exercise increased (p < 0.05) for both ECC (12-37%) and CON (27-68%). Both groups improved (p < 0.05) 6-min walk distance (ES = 0.083, ECC 12.2 ± 2.3%; CON 12.5 ± 15.3%) and chair rise time (ES = 0.463, ECC - 13.4 ± 25.4%; CON - 20.0 ± 53.3%) but only ECC improved (p < 0.05) the timed up-and-go test (- 11.3 ± 13.6%, ES 0.014). No significant changes in balance tests were found for both groups. CONCLUSION: These results did not fully support the hypothesis but showed that ECC was as effective as CON to improve body composition, muscle strength, and physical function with lesser RPE. Future studies should investigate whether larger differences between ECC and CON are evident when increasing the exercise frequency and matching the intensities of the two-exercise protocols. Trial registration ACTRN12621001026819 (retrospectively registered on 5th Aug 2021).

Comparison between eccentric and concentric resistance exercise training without equipment for changes in muscle strength and functional fitness of older adults.

PURPOSE: The present study tested the hypothesis that resistance exercise training focusing on eccentric muscle contractions would improve muscle strength and functional physical fitness more than concentric contraction-focused resistance training in older adults. METHODS: Healthy older adults (65-84 years) were placed into eccentric (ECC; n = 9) or concentric training group (CON; n = 8). They performed 4-6 basic manual resistance exercises focusing on either eccentric or concentric muscle contractions once at a community centre and at least twice at home a week for 8 weeks. Muscle thickness of the quadriceps femoris (MT), knee extensor maximal voluntary isometric contraction strength (MVC), 30-second chair stand (CS), 3-metre timed up and go (TUG), 2-minute step (2MS), sit and reach (SR), and static balance with eyes open and closed (Bal-EC) were assessed before and 7 days after the last community centre session. RESULTS: Changes in MT (ECC: 21.6 ± 9.2% vs CON: 6.7 ± 7.1%), MVC (38.3 ± 22.6% vs 8.2 ± 8.4%), CS (51.0 ± 21.7% vs 34.6 ± 28.3%), TUG (16.7 ± 9.9% vs 6.3 ± 7.7%), 2MS (9.9 ± 6.0% vs 6.0 ± 7.3%) and Bal-EC (35.1 ± 6.7% vs 8.8 ± 16.2%) from baseline were greater (P < 0.05) for the ECC than the CON group. CONCLUSION: These results show that the eccentric manual resistance exercise training was more effective for improving lower limb strength, mobility, and postural stability of older adults when compared with the concentric training. This suggests the significance of emphasising eccentric muscle contractions in movements to maintain and improve physical function.

An optogenetic system for interrogating the temporal dynamics of Akt.

The dynamic activity of the serine/threonine kinase Akt is crucial for the regulation of diverse cellular functions, but the precise spatiotemporal control of its activity remains a critical issue. Herein, we present a photo-activatable Akt (PA-Akt) system based on a light-inducible protein interaction module of Arabidopsis thaliana cryptochrome2 (CRY2) and CIB1. Akt fused to CRY2phr, which is a minimal light sensitive domain of CRY2 (CRY2-Akt), is reversibly activated by light illumination in several minutes within a physiological dynamic range and specifically regulates downstream molecules and inducible biological functions. We have generated a computational model of CRY2-Akt activation that allows us to use PA-Akt to control the activity quantitatively. The system provides evidence that the temporal patterns of Akt activity are crucial for generating one of the downstream functions of the Akt-FoxO pathway; the expression of a key gene involved in muscle atrophy (Atrogin-1). The use of an optical module with computational modeling represents a general framework for interrogating the temporal dynamics of biomolecules by predictive manipulation of optogenetic modules.

Effects of exercise training on gut hormone levels after a single bout of exercise in middle-aged Japanese women.

The purpose of this study was to investigate the effects of 12 weeks of exercise training on gut hormone levels after a single bout of exercise in middle-aged Japanese women. Twenty healthy middle-aged women were recruited for this study. Several measurements were performed pre and post exercise training, including: body weight and composition, peak oxygen consumption (peak VO2), energy intake after the single bout of exercise, and the release of gut hormones with fasting and after the single bout of exercise. Exercise training resulted in significant increases in acylated ghrelin fasting levels (from 126.6 ± 5.6 to 135.9 ± 5.4 pmol/l, P < 0.01), with no significant changes in GLP-1 (from 0.54 ± 0.04 to 0.55 ± 0.03 pmol/ml) and PYY (from 1.20 ± 0.07 to 1.23 ± 0.06 pmol/ml) fasting levels. GLP-1 levels post exercise training after the single bout of exercise were significantly higher than those pre exercise training (areas under the curve (AUC); from 238.4 ± 65.2 to 286.5 ± 51.2 pmol/ml x 120 min, P < 0.001). There was a tendency for higher AUC for the time courses of PYY post exercise training than for those pre exercise training (AUC; from 519.5 ± 135.5 to 551.4 ± 128.7 pmol/ml x 120 min, P = 0.06). Changes in (delta) GLP-1 AUC were significantly correlated with decreases in body weight (r = -0.743, P < 0.001), body mass index (r = -0.732, P < 0.001), percent body fat (r = -0.731, P < 0.001), and energy intake after a single bout exercise (r = -0.649, P < 0.01) and increases in peak VO2 (r = 0.558, P < 0.05). These results suggest that the ability of exercise training to create a negative energy balance relies not only directly on its impact on energy expenditure, but also indirectly on its potential to modulate energy intake.

Changes in salivary antimicrobial peptides, immunoglobulin A and cortisol after prolonged strenuous exercise.

The aim of the present study was to examine whether amount of oral antimicrobial components, human ß-defensin-2 (HBD-2), cathelicidin (LL-37), and immunoglobulin A (IgA), might be affected by prolonged strenuous exercise. Ten young male volunteers either exercised on recumbent ergometer at 75% [Formula: see text] for 60 min (exercise session) or sat quietly (resting session). Saliva samples were obtained at 60-min intervals during sessions for measurements of saliva antimicrobial components (HBD-2, LL-37, and IgA), saliva cortisol and osmolality. Saliva flow rate was decreased and saliva osmolality was increased during the 60-min exercise. Saliva HBD-2 and LL-37 concentrations and secretion rates were increased during and after the exercise, whereas saliva IgA concentration and secretion rates were decreased after the exercise. Saliva cortisol was increased during and after the exercise. The areas under the curve of the time courses of saliva levels of HBD-2 and LL-37 were negatively correlated with those of cortisol levels in saliva. The present findings suggested that a single bout of prolonged strenuous exercise caused a transient increase in the oral HBD-2 and LL-37 levels.

Effects of aquatic exercise training using water-resistance equipment in elderly.

To prevent falls in Japan, both gait and resistance training of the lower extremities are recommended. However, resistance training for the elderly induces muscle damage. Recently, aquatic exercise using water buoyancy and resistance have commonly been performed by the elderly. We have now produced new water-resistance equipment. The purpose of the present study was to evaluate the efficacy of aquatic exercise training using the new equipment for the elderly. Subjects were divided into two groups: a resistance group of 12 subjects (using water-resistance equipment) and a non-resistance group of eight subjects (without the equipment). The aquatic exercise training was 90 min, three times per week for 8 weeks, and mostly consisted of walking. All subjects underwent anthropometric measurements, physical performance testing, and profile of mood states (POMS). Significant improvements were observed in muscle strength in plantar flexion, and the timed up and go test (TUG) in both groups. Additionally, 10-m obstacle walking and 5-m maximum walking speed and length with eye-open were significantly improved in the resistance group. Also, a low negative correlation was found between the degree of change in TUG and POMS (tension and anxiety) scores in the resistance group. As it became easier to maintain posture, stand, and move, tension and anxiety in everyday life were alleviated with improvement of strength of the lower extremities and balance function. The present aquatic exercise training using water-resistance equipment may be used by the elderly to improve balance and walking ability, which are associated with the prevention of falls.

Comparable effects of moderate intensity exercise on changes in anorectic gut hormone levels and energy intake to high intensity exercise.

There is growing interest in the effects of exercise on plasma gut hormone levels and subsequent energy intake (EI) but the effects of mode and exercise intensity on anorectic hormone profiles on subsequent EI remain to be elucidated. We aimed to investigate whether circulating peptide YY(3-36) (PYY(3-36)) and glucagon-like peptide-1 (GLP-1 or GCG as listed in the HUGO Database) levels depend on exercise intensity, which could affect subsequent EI. Ten young male subjects (mean+/-s.d., age: 23.4+/-4.3 years, body mass index: 22.5+/-1.0 kg/m(2), and maximum oxygen uptake (VO(2 max)): 45.9+/-8.5 ml/kg per min) received a standardized breakfast, which was followed by constant cycling exercise at 75% VO(2 max) (high intensity session), 50% VO(2 max) (moderate intensity session), or rest (resting session) for 30 min. At lunch, a test meal was presented, and EI was calculated. Blood samples were obtained during three sessions for measurements of glucose, insulin, PYY(3-36), and GLP-1, which includes GLP-1 (7-36) amide and GLP-1 (9-36) amide. Increases in blood PYY(3-36) levels were dependent on the exercise intensity (effect of session: P<0.001 by two-way ANOVA), whereas those in GLP-1 levels were similar between two different exercise sessions. Of note, increase in area under the curve values for GLP-1 levels was negatively correlated with decrease in the EI in each exercise session (high: P<0.001, moderate: P=0.002). The present findings raise the possibility that each gut hormone exhibits its specific blood kinetics in response to two different intensities of exercise stimuli and might play differential roles in regulation of EI after exercise.

Changes in gut hormone levels and negative energy balance during aerobic exercise in obese young males.

We examined whether changes in gut hormone levels due to a single bout of aerobic exercise differ between obese young males and normal controls, and attempted to determine the involvement of hormonal changes during exercise in the regulation of energy balance (EB) in these obese subjects. Seven obese and seven age-matched subjects of normal weight participated in exercise and rest sessions. Subjects consumed a standardized breakfast that was followed by constant cycling exercise at 50% VO(2max) or rest for 60 min. At lunch, a test meal was presented, and energy intake (EI) and relative energy intake (REI) were calculated. Blood samples were obtained at 30 min intervals during both sessions for measurement of glucose, insulin, glucagon, ghrelin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1). Plasma levels of PYY and GLP-1 were increased by exercise, whereas plasma ghrelin levels were unaffected by exercise. The areas under the curve (AUC) of the time courses of PYY and GLP-1 levels did not significantly differ between the two groups. In contrast, EI and REI were decreased by exercise in both groups, and energy deficit was significantly larger in obese subjects than in normal controls. The present findings suggest that short-term EB during a single exercise session might be regulated not by increased amounts of these gut hormones per se.

First trace and body fossil evidence of a burrowing, denning dinosaur.

A fossil discovery in the mid-Cretaceous Blackleaf Formation of southwest Montana, USA, has yielded the first trace and body fossil evidence of burrowing behaviour in a dinosaur. Skeletal remains of an adult and two juveniles of Oryctodromeus cubicularis gen. et sp. nov. a new species of hypsilophodont-grade dinosaur, were found in the expanded distal chamber of a sediment-filled burrow. Correspondence between burrow and adult dimensions supports Oryctodromeus as the burrow maker. Additionally, Oryctodromeus exhibits features of the snout, shoulder girdle and pelvis consistent with digging habits while retaining cursorial hindlimb proportions. Association of adult and young within a terminal chamber provides definitive evidence of extensive parental care in the Dinosauria. As with modern vertebrate cursors that dig, burrowing in Oryctodromeus may have been an important adaptation for the rearing of young. Burrowing also represents a mechanism by which small dinosaurs may have exploited the extreme environments of polar latitudes, deserts and high mountain areas. The ability among dinosaurs to find or make shelter may contradict some scenarios of the Cretaceous-Paleogene impact event. Burrowing habits expand the known range of nonavian dinosaur behaviours and suggest that the cursorial ancestry of dinosaurs did not fully preclude the evolution of different functional regimes, such as fossoriality.