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This study provides causal evidence demonstrating that consuming a high flavanol diet improves dentate gyrus function and dentate gyrus–dependent cognitive functions in aged humans. The dentate gyrus (DG) is a region in the hippocampal formation whose function declines in association with human aging and is therefore considered to be a possible source of age-related memory decline. Causal evidence is needed, however, to show that DG-associated memory decline in otherwise healthy elders can be improved by interventions that enhance DG function. We addressed this issue by first using a high-resolution variant of functional magnetic resonance imaging (fMRI) to map the precise site of age-related DG dysfunction and to develop a cognitive task whose function localized to this anatomical site. Then, in a controlled randomized trial, we applied these tools to study healthy 50–69-year-old subjects who consumed either a high or low cocoa flavanol–containing diet for 3 months. A high-flavanol intervention was found to enhance DG function, as measured by fMRI and by cognitive testing. Our findings establish that DG dysfunction is a driver of age-related cognitive decline and suggest non-pharmacological means for its amelioration.

To determine the separate effects of exercise intensity and amount on interindividual cardiorespiratory fitness (CRF) response. Participants were 121 (75 females, 62%) sedentary, middle-aged (mean [SD] age, 53.2 [7.5] years), abdominally obese adults who completed at least 90% of 5 weekly exercise sessions prescribed over a 24-week intervention. Participants were randomly assigned to (1) low-amount, low-intensity exercise (LALI) (180 and 300 kcal per session for women and men, respectively, at 50% of CRF [V˙O2peak]; n=39), (2) high-amount, low-intensity exercise (HALI) (360 and 600 kcal per session for women and men, respectively, at 50% of CRF; n=51), or high-amount, high-intensity exercise (HAHI) (360 and 600 kcal per session for women and men, respectively, at 75% of CRF; n=31). Cardiorespiratory fitness was measured using a treadmill test at 4, 8, 16, and 24 weeks. The study duration was September 1, 2009, through May 31, 2013. Cardiorespiratory fitness increased within all 3 groups at 24 weeks (P<.001). At 24 weeks, 38.5% (15 of 39), 17.6% (9 of 51), and 0% (0 of 31) of the participants within the LALI, HALI, and HAHI groups, respectively, were CRF nonresponders. At a fixed exercise intensity, increasing exercise amount reduced the rate of nonresponse by 50% (P=.02). At a fixed amount of exercise, increasing the exercise intensity eliminated nonresponse (P=.001). Exposure to exercise decreased the number of CRF nonresponders between 4 and 8 weeks for LALI and by 16 weeks for HALI but plateaued thereafter. For HAHI, the number of CRF nonresponders decreased continually over the 24 weeks. For a fixed amount of exercise, increasing exercise intensity consistent with consensus recommendations eliminated CRF nonresponse. Low-intensity exercise may not be sufficient to improve CRF for a substantial proportion of sedentary obese adults.

The purpose of this study was to assess the accuracy of the Cosmed K5 portable metabolic system dynamic mixing chamber (MC) and breath-by-breath (BxB) modes against the criterion Douglas bag (DB) method. Fifteen participants (mean age±SD, 30.6±7.4 yrs) had their metabolic variables measured at rest and during cycling at 50, 100, 150, 200, and 250W. During each stage, participants were connected to the first respiratory gas collection method (randomized) for the first four minutes to reach steady state, followed by 3-min (or 5-min for DB) collection periods for the resting condition, and 2-min collection periods for all cycling intensities. Collection periods for the second and third methods were preceded by a washout of 1-3 min. Repeated measures ANOVAs were used to compare metabolic variables measured by each method, for seated rest and each cycling work rate. For ventilation (VE) and oxygen uptake (VO2), the K5 MC and BxB modes were within 2.1 l/min (VE) and 0.08 l/min (VO2) of the DB (p≥0.05). Compared to DB values, carbon dioxide production (VCO2) was significantly underestimated by the K5 BxB mode at work rates ≥150W by 0.12-0.31 l/min (p<0.05). K5 MC and BxB respiratory exchange ratio values were significantly lower than DB at cycling work rates ≥100W by 0.03-0.08 (p<0.05). Compared to the DB method, the K5 MC and BxB modes are acceptable for measuring VE and VO2 across a wide range of cycling intensities. Both K5 modes provided comparable values to each other.

Assessing the total energy expenditure (TEE) and the levels of physical activity in free-living conditions with non-invasive techniques remains a challenge. The purpose of the present study was to investigate the accuracy of a new uniaxial accelerometer for assessing TEE and physical-activity-related energy expenditure (PAEE) over a 24 h period in a respiratory chamber, and to establish activity levels based on the accelerometry ranges corresponding to the operationally defined metabolic equivalent (MET) categories. In study 1, measurement of the 24 h energy expenditure of seventy-nine Japanese subjects (40 (SD 12) years old) was performed in a large respiratory chamber. During the measurements, the subjects wore a uniaxial accelerometer (Lifecorder; Suzuken Co. Ltd, Nagoya, Japan) on their belt. Two moderate walking exercises of 30 min each were performed on a horizontal treadmill. In study 2, ten male subjects walked at six different speeds and ran at three different speeds on a treadmill for 4 min, with the same accelerometer. O2 consumption was measured during the last minute of each stage and was expressed in MET. The measured TEE was 8447 (SD 1337) kJ/d. The accelerometer significantly underestimated TEE and PAEE (91·9 (SD 5·4) and 92·7 (SD 17·8) % chamber value respectively); however, there was a significant correlation between the two values (r 0·928 and 0·564 respectively; P<0·001). There was a strong correlation between the activity levels and the measured MET while walking (r2 0·93; P<0·001). Although TEE and PAEE were systematically underestimated during the 24 h period, the accelerometer assessed energy expenditure well during both the exercise period and the non-structured activities. Individual calibration factors may help to improve the accuracy of TEE estimation, but the average calibration factor for the group is probably sufficient for epidemiological research. This method is also important for assessing the diurnal profile of physical activity.

PurposeTo determine the effect of prolonged exercise on moderate-to-heavy intensity transition power output and heart rate.MethodsFourteen endurance-trained cyclists and triathletes took part in the present investigation (13 males, 1 female, V·O2peak 59.9 ± 6.8 mL.kg−1.min−1). Following a characterisation trial, participants undertook a five-stage incremental step test to determine the power output and heart rate at the moderate-to-heavy intensity transition before and after two hours of cycling at 90% of the estimated power output at first ventilatory threshold (VT1).ResultsPower output at the moderate-to-heavy intensity transition significantly decreased following acute prolonged exercise when determined using expired gases (VT1, 217 ± 42 W vs. 196 ± 42 W, P < 0.0001) and blood lactate concentrations (LoglogLT, 212 ± 47 W vs. 190 ± 47 W, P = 0.004). This was attributable to loss of efficiency (VT1, -8 ± 10 W; LoglogLT, − 7 ± 9 W) and rates of metabolic energy expenditure at the transition (VT1, − 14 ± 11 W; LoglogLT, − 15 ± 22 W). The heart rate associated with the moderate-to-heavy intensity transition increased following acute prolonged exercise (VT1, 142 ± 9 beats.min−1 vs. 151 ± 12 beats.min−1, P < 0.001; LoglogLT, 140 ± 13 beats.min−1 vs. 150 ± 15 beats.min−1, P = 0.006).ConclusionThese results demonstrate the external work output at the moderate-to-heavy intensity transition decreases during prolonged exercise due to decreased efficiency and rates of metabolic energy expenditure, but the associated heart rate increases. Therefore, individual assessments of athlete ‘durability’ are warranted.

Despite a practical guideline of 30-meter walking path during 6-minute walk test (6MWT), such walking course length is not possible in every clinical setting due to unavailable sufficient space. Existing evidence has investigated using several shorter course lengths, it remains unclear whether a walking course length shorter than the standard walking course length is appropriate for 6MWD testing. This study aimed (i) to compare maximum walking distances at various shorter walking course lengths (i.e., 10, 20, and 25 meters) and 30 meters, and (ii) to assess agreements in maximum walking distances achieved at intervals below 30 meters, specifically 10, 15, 20, and 25 meters. This study was a cross-sectional with cross-over design. Forty-eight healthy participants were randomly ordered to perform 6MWT with five different walkways (10, 15, 20, 25, 30 meters). The maximum walking distance (six-minute walk distance, 6MWD) covered was recorded. Eligible participants aged 41.0 ± 17.2 years, with equal sex (24 males) participated in this study. The 6MWD at 10, 15, and 20-meter walkways significantly shorter than the 30-meter standard walkway (489.6 ± 59.3 m, 513.1 ± 62.6 m, 524.7 ± 63.7 m vs 539.1 ± 63.1 m, respectively (P<0.01)). Very strong agreement was observed at 15, 20, and 25 meters with the standard 30 meters (0.819-0.875, P<0.001). Subgroup analysis showed strong to very strong agreement in 10-meter walkway length onwards with the standard walkway length among older adults (0.757-0.918, P<0.001). Testing on 20 meters walkway and shorter yielded varied results compared to the standard 30-meter walk, with exceptional congruence observed at 15 meters onwards. In particular, a minimum walkway of 10 meters had strong agreement with a standard 30-meter walkway in elderly.

Transcatheter aortic valve implantation (TAVI) is increasingly applied for aortic stenosis in elderly patients with impaired mobility and reduced quality of life. These patients may particularly benefit from postinterventional exercise programs, but no randomized study has evaluated the safety and efficacy of exercise in this population. In a prospective pilot study, 30 patients after TAVI (mean age, 81±6 years, 44% female, 83±34 days postintervention) were randomly allocated 1:1 to a training group (TG) performing 8 weeks of supervised combined endurance and resistance exercise or to usual care. The formal primary efficacy end point was between-group difference in change in peak oxygen uptake assessed by cardiopulmonary exercise testing; secondary end points included muscular strength, 6-minute walk distance, and quality of life (Kansas City Cardiomyopathy Questionnaire and Medical Outcomes Study 12-Item Short-Form Health Survey questionnaires). Safety was assessed by documenting training-related adverse events, prosthesis, and renal function. Significant changes in favor of TG were observed for peak oxygen uptake (group difference, 3.7 mL/min per kg [95% CI, 1.1-6.3; P=.007]), muscular strength (bench press, 6 kg [95% CI, 3-10; P=.002]; rowing, 7 kg [95% CI, 3-11; P<.001]; pulldown, 9 kg [95% CI, 4-14; P=.001]; shoulder press, 5 kg [95% CI, 1-8; P=.008]; leg press, 17 kg [95% CI 6-28; P=.005]), components of quality of life (Kansas City Cardiomyopathy Questionnaire physical limitation, 19.2 [95% CI, 4.1-34.2; P=.015]; symptom burden, 12.3 [95% CI, 0.5-24.0; P=.041]; clinical summary, 12.4 [3.4-21.4; P=.009]), but not for other questionnaire subscales and 6-minute walk distance (15 m [95% CI, −23 to 53; P=.428]). Three dropouts unrelated to exercise occurred (TG=2; usual care,=1); prosthesis and renal function were not affected by the exercise intervention. In patients after TAVI, exercise training appears safe and highly effective with respect to improvements in exercise capacity, muscular strength, and quality of life. Clinical Trial Registration: Clinicaltrials.govNCT01935297.

Background Exercise is often proposed as a non-pharmacological intervention to delay cognitive decline in people with dementia, but evidence remains inconclusive. Previous studies suggest that combining physical exercise with cognitive stimulation may be more successful in this respect. Exergaming is a promising intervention in which physical exercise is combined with cognitively challenging tasks in a single session. The aim of this study was to investigate the effect of exergame training and aerobic training on cognitive functioning in older adults with dementia. Methods A three-armed randomized controlled trial (RCT) compared exergame training, aerobic training and an active control intervention consisting of relaxation and flexibility exercises. Individuals with dementia were randomized and individually trained three times a week during 12 weeks. Cognitive functioning was measured at baseline, after the 12-week intervention period and at 24-week follow-up by neuropsychological assessment. The domains of executive function, episodic memory, working memory and psychomotor speed were evaluated. Test scores were converted into standardized z -scores that were averaged per domain. Between-group differences were analysed with analysis of covariance. Results Data from 115 people with dementia (mean (SD) age = 79.2 (6.9) years; mean (SD) MMSE score = 22.9 (3.4)) were analysed. There was a significant improvement in psychomotor speed in the aerobic and exergame groups compared to the active control group (mean difference domain score (95% CI) aerobic versus control 0.370 (0.103–0.637), p  = 0.007; exergame versus control 0.326 (0.081–0.571), p  = 0.009). The effect size was moderate (partial η 2  = 0.102). No significant differences between the intervention and control groups were found for executive functioning, episodic memory and working memory. Conclusions To our knowledge, this is the first RCT evaluating the effects of exergame training and aerobic training on cognitive functioning in people with dementia. We found that both exergame training and aerobic training improve psychomotor speed, compared to an active control group. This finding may be clinically relevant as psychomotor speed is an important predictor for functional decline. No effects were found on executive function, episodic memory and working memory. Trial registration Netherlands Trial Register, NTR5581 . Registered on 7 October 2015.