Eveleen Sng

Randomized controlled trial evaluating the temporal effects of high‐intensity exercise on learning, short‐term and long‐term memory, and prospective memory

The broader purpose of this study was to examine the temporal effects of high‐intensity exercise on learning, short‐term and long‐term retrospective memory and prospective memory. Among a sample of 88 young adult participants, 22 were randomized into one of four different groups: exercise before learning, control group, exercise during learning, and exercise after learning. The retrospective assessments (learning, short‐term and long‐term memory) were assessed using the Rey Auditory Verbal Learning Test. Long‐term memory including a 20‐min and 24‐hr follow‐up assessment. Prospective memory was assessed using a time‐based procedure by having participants contact (via phone) the researchers at a follow‐up time period. The exercise stimulus included a 15‐min bout of progressive maximal exertion treadmill exercise. High‐intensity exercise prior to memory encoding (vs. exercise during memory encoding or consolidation) was effective in enhancing long‐term memory (for both 20‐min and 24‐h follow‐up assessments). We did not observe a differential temporal effect of high‐intensity exercise on short‐term memory (immediate post‐memory encoding), learning or prospective memory. The timing of high‐intensity exercise may play an important role in facilitating long‐term memory.

The Effects of Exercise on Memory Function Among Young to Middle-Aged Adults: Systematic Review and Recommendations for Future Research

Objective: To systematically summarize the experimental effects of exercise on cognitive-related memory function among young to middle-aged adults, which has yet to be done in the literature. Data Source: PubMed. Study Inclusion and Exclusion Criteria: Studies were included if they were published in the English language, indexed in PubMed, employed an experimental study design (eg, traditional parallel group randomized controlled trial: either acute intervention or chronic/training intervention study), and conducted among human adults. Studies were excluded if nonhumans (ie, animal models) were studied, if children/adolescents (<18 years) or older adults (>50 years) were evaluated, and if select chronic diseases (eg, diabetes and dementia) were present. Data Extraction: A systematic review approach was employed. Data Synthesis: An extraction table was created synthesizing the key results, and recommendations for future research are emphasized. Results: Among the 17 evaluated studies, 2 were published before the year 2000 (ie, 1998 and 1999), 2 were published in 2007, and the remaining 13 were published in the years 2011 and beyond. This highlights the emergence of this research topic within this age-group (young to middle-aged adults). Among the 17 evaluated studies, 14 were conducted among healthy samples, with 3 conducted among those with a diagnosis of depression. Among the 17 studies, 4 employed a chronic training protocol, with 13 utilizing an acute exercise protocol. Among the 3 experimental studies in the depressed population, all demonstrated a favorable effect of exercise on memory function. Among the 14 trials in the nondepressed population, 10 (71%) demonstrated a favorable effect of exercise on some aspect of memory function. Conclusion: Acute and chronic exercise appears to play a pronounced effect on memory function among young to middle-aged adults. Implications and recommendations for future research are outlined in this systematic review.

Mode-specific physical activity and leukocyte telomere length among U.S. adults: Implications of running on cellular aging

BACKGROUND Previous research demonstrates that physical activity participation is associated with longer leukocyte telomere length, with shorter leukocyte telomere length being a hallmark characteristic of cellular aging. What remains under-investigated, however, is whether there is a mode-specific association of physical activity on leukocyte telomere length, which was this studys purpose. METHODS Data from the 1999-2002 National Health and Nutrition Examination Survey were used (N=6474 adults analyzed). Leukocyte telomere length was assessed using quantitative polymerase chain reaction. Physical activity was assessed via self-report, with participants classified as meeting physical activity guidelines (≥2000 metabolic equivalent of task-min-month) for 9 separate physical activities, including aerobics (unweighted percent meeting guidelines: 2.98%; n=193), basketball (2.0%; n=129), bicycling (3.71%; n=240), dance (2.30%; n=149), running (3.09%; n=200), stair climbing (1.33%, n=86), swimming (1.85%, n=120), walking (13.53%; n=876), and weight lifting (2.61%; n=169). RESULTS In a single multivariable linear regression model including the independent variables of age, gender, race-ethnicity, weight status, total cholesterol, C-reactive protein, total metabolic equivalent of task-min-month of physical activity and the 9 binary meeting physical activity guideline variables, the only mode of physical activity that was significantly associated with leukocyte telomere length was meeting physical activity guidelines from running (β=0.06; 95% CI: 0.01-0.11; P=0.03). CONCLUSION Running-specific physical activity was the only evaluated physical activity associated with leukocyte telomere length, which may provide one potential mechanism (i.e., leukocyte telomere length) through which running-based physical activity may help to prevent cardiovascular disease and premature mortality.

Temporal Effects of Acute Walking Exercise on Learning and Memory Function

Purpose: To evaluate the temporal effects of acute exercise on episodic memory. Design: A quasi-experimental study. Sample: Eighty-eight college students (N = 22 per group). Measures: Four experimental groups were evaluated, including a control group, exercising prior to memory encoding, exercising during encoding, and exercising during memory consolidation. The exercise stimulus consisted of a 15-minute moderate-intensity walk on a treadmill. Participants completed the Rey Auditory Verbal Learning Test (RAVLT) to assess learning and memory. Prospective memory was assessed via a Red Pen Task. Long-term memory (recognition and attribution) of the RAVLT was assessed 20 minutes and 24 hours after exercise. Analysis: Repeated-measures analysis of variance (ANOVA) assessed the performance of RAVLT scores of trials 1 to 5 across groups. One-way ANOVA assessed the performance of individual trials across groups, whereas χ2 assessed the performance of the Red Pen Task across groups. Results: Regarding learning, the interaction of groups × trial was marginally statistically significant (F 12,332 = 1.773, P = .05), indicating that the group which exercised before encoding did better than the group that exercised during encoding and consolidation. For both 24-hour recognition and attribution performance, the group that exercised before memory encoding performed significantly better than the group that exercised during consolidation (P = .05 recognition, P = .006 attribution). Discussion: Engaging in a 15-minute bout of moderate-intensity walking before a learning task was effective in influencing long-term episodic memory.

The effects of objectively measured sedentary behavior on all-cause mortality in a national sample of adults with diabetes

BACKGROUND Diabetes is a highly prevalent chronic disease that has been increasing globally and is the seventh leading cause of death in the United States. Sedentary behavior is associated with increased risk of diabetes and is unfavorably related to all-cause mortality, but there are limited studies examining the sedentary-mortality relationship among those with diabetes, which was the purpose of this study. METHODS Using data from the 2003-2006 NHANES, 712 adult participants with evidence of diabetes had complete data on the study variables. A multivariable Cox proportional hazard model was used to examine the association between objectively measured sedentary behavior and all-cause mortality among this diabetic sample. RESULTS Results showed that for every 60min/day increase in sedentary behavior, independent of moderate-to-vigorous physical activity (MVPA) and other covariates, adults with diabetes had a 13% increased risk of all-cause mortality (HRadjusted=1.13; 95% CI=1.03-1.24; P=0.01). However, after adjusting for total physical activity (light and MVPA), sedentary behavior was no longer associated with mortality risk (HRadjusted=1.04; 95% CI=0.92-1.16; P=0.46). CONCLUSION Among those with diabetes, sedentary behavior may not have increased mortality risk independent of total physical activity behavior.

Physical Activity and Residual-specific Mortality among Adults in the United States

INTRODUCTION The purpose of this study was to examine the association between physical activity and residual-specific mortality (deaths not from the major nine causes of death) among a national sample of adults in the United States, which has yet to be investigated. METHODS Data from the 1999-2006 National Health and Nutrition Examination Survey were employed, with 16,329 participants constituting the analytical sample. Participants were followed through 2011, including a median follow-up of 101 months. Moderate to vigorous physical activity (MVPA) was assessed via self-report and accelerometry. RESULTS After adjusting for age, gender, race-ethnicity, blood pressure, and other covariates, participants who self-reported meeting physical activity guidelines (≥2000 MET·min·month) had a 33% reduced risk for residual-specific mortality (HR = 0.67; 95% confidence interval, 0.53-0.85; P = 0.001). With regard to accelerometry-assessed MVPA, for every 30 min·d increase in MVPA, participants had a 53% reduced hazard of residual-specific mortality (HR = 0.47; 95% confidence interval, 0.26-0.84; P = 0.01; N = 7739). CONCLUSION The major finding of this study was that physical activity was inversely associated with residual-specific mortality risk.

Muscle strengthening activity associates with reduced all-cause mortality in COPD:

Objective Emerging research suggests that aerobic-based physical activity may help to promote survival among chronic obstructive pulmonary disease patients. However, the extent to which engagement in resistance training on survival among chronic obstructive pulmonary disease patients is relatively unknown. Therefore, the purpose of this study was to examine the independent associations of muscle strengthening activities on all-cause mortality among a national sample of U.S. adults with chronic obstructive pulmonary disease. We hypothesize that muscle strengthening activities will be inversely associated with all-cause mortality. Methods Data from the 2003–2006 NHANES were employed, with follow-up through 2011. Aerobic-based physical activity was objectively measured via accelerometry, muscle strengthening activities engagement was assessed via self-report, and chronic obstructive pulmonary disease was assessed via physician-diagnosis. Results Analysis included 385 adults (20 + yrs) with chronic obstructive pulmonary disease, who represent 13.3 million chronic obstructive pulmonary disease patients in the USA. The median follow-up period was 78 months (IQR=64–90), with 82 chronic obstructive pulmonary disease patients dying during this period. For a two muscle strengthening activity sessions/week increase (consistent with national guidelines), chronic obstructive pulmonary disease patients had a 29% reduced risk of all-cause mortality (HR=0.71; 95% CI: 0.51–0.99; P = 0.04). Conclusion Participation in muscle strengthening activities, independent of aerobic-based physical activity and other potential confounders, is associated with greater survival among chronic obstructive pulmonary disease patients.

Experimental Effects of Acute Exercise on Episodic Memory Function: Considerations for the Timing of Exercise

Our previous work employing a between-subject randomized controlled trial design suggests that exercising prior to memory encoding is more advantageous in enhancing retrospective episodic memory function when compared to exercise occurring during or after memory encoding. The present experiment evaluates this potential temporal effect of acute exercise on memory function while employing a within-subject, counterbalanced design. In a counterbalanced order (via Latin squares), 24 participants completed four visits including (1) exercising (moderate-intensity walking) prior to memory encoding, (2) exercising during memory encoding, (3) exercising after memory encoding, and (4) a control visit (no exercise). Retrospective memory function (short term and long term; 24-hour follow-up) was assessed from a multitrial word list. Prospective memory was assessed from a time-based task. Compared to all other visits, short-term memory was greater in the visit that involved exercising prior to memory encoding (F = 3.76; P = .01; η2 = .79). Similar results occurred for long-term memory, with no significant effects for prospective memory performance. We provide robust evidence demonstrating that acute moderate-intensity exercise prior to memory encoding is optimal in enhancing short-term and long-term memory function when compared to no exercise as well as exercising during and after memory encoding.

Experimental effects of acute exercise on episodic memory acquisition: Decomposition of multi-trial gains and losses

OBJECTIVE Research demonstrates that acute exercise may enhance retention of multi-trial episodic memories. Previous work has examined the effects of exercise on the mean level of memory recall. However, no study has examined whether exercise can influence the acquisition of new items, which was the purpose of this experiment. METHODS Using a randomized controlled trial design, participants (young adults; Mage=22yrs) completed either a high-intensity bout of treadmill exercise for 15-min (n=22) or sat (n=22) prior to completing a multi-trial episodic memory task. This task involved recalling 15 words for six successive trials, as well as after a 20-min delay (Trial 7). The performance on the multiple trials was categorized into gains (items not recalled on Trial n that were recalled on Trial n+1) and losses (items recalled on Trial n that were not recalled on Trial n+1). RESULTS The exercise group recalled more words on Trial 6 (11.4 vs. 9.7; P=0.009) and after the 20-min delay (10.9 vs. 9.4; P=0.01). The exercise group (vs. control) had a smaller proportion of losses from Trial 3-4 (10.4% vs. 20.3%; P=0.04) and had a greater proportion of gains from Trial 5-6 (38.5% vs. 14.8%; P=0.01). CONCLUSIONS The exercise-induced multi-trial memory effect may be influenced by greater item gains.

Randomized Controlled Trial Considering Varied Exercises for Reducing Proactive Memory Interference

We evaluated the effects of exercise on proactive memory interference. Study 1 (n = 88) employed a 15-min treadmill walking protocol, while Study 2 (n = 88) included a 15-min bout of progressive maximal exertion treadmill exercise. Each study included four distinct groups, in which groups of 22 participants each were randomly assigned to: (a) exercise before memory encoding, (b) a control group with no exercise, (c) exercise during memory encoding, and (d) exercise after memory encoding (i.e., during memory consolidation). We used the Rey Auditory Verbal Learning Test (RAVLT) to assess proactive memory interference. In both studies, the group that exercised prior to memory encoding recalled the most words from list B (distractor list) of the RAVLT, though group differences were not statistically significant for Study 1 (walking exercise) (p = 0.521) or Study 2 (high-intensity exercise) (p = 0.068). In this sample of young adults, high intensity exercise prior to memory encoding showed a non-significant tendency to attenuate impairments in recall attributable to proactive memory interference. Thus, future work with larger samples is needed to clarify potential beneficial effects of exercise for reducing proactive memory interference.