Walking Bouts Research Articles

Are patients with knee osteoarthritis and patients with knee joint replacement as physically active as healthy persons?

BackgroundIt is well documented that patients with knee osteoarthritis (KOA) suffer from reduced physical function and that function of the affected knee is improved after knee joint replacement (KJR). However, it remains uncertain whether patients with KOA are less physically active than healthy people and whether patients increase their level of physical activity after surgery to a level comparable with that of healthy people. The aim of this study was to examine whether patients with KOA are less physically active than healthy participants and whether patients who have undergone KJR show an increased activity and achieve the same level of physical activity as healthy participants 5 years postoperatively. MethodsFifty-four patients with KOA (29 women; mean age 62 ± 8.6; mean body mass index (BMI) 27 ± 5), 52 patients who had KJR due to KOA 5 years earlier (26 women; mean age 66 ± 7.2; mean BMI 30 ± 5) and 171 healthy participants (76 women, mean age 64 ± 9.7, mean BMI 26 ± 5) were included in this cross-sectional study. The level of physical activity was measured over a mean period of 5.5 days with a triaxial accelerometer mounted on the thigh. Number of daily steps, number of daily short walking bouts of <10 s duration and number of daily transfers from sitting to standing position were recorded. Data were analysed using two sample t tests and were adjusted for age, gender and BMI. ResultsPatients with KOA did not differ significantly from healthy participants regarding daily steps (+321, p = 0.50) or daily transfers from sitting to standing (+1.9, p = 0.52) but performed significantly less daily short walking bouts <10 s (−11.9, p = 0.02). Patients after KJR did not differ significantly from healthy participants regarding daily steps (−281, p = 0.60) of transfers from sitting to standing position (−3.2, p = 0.32) but performed significantly less daily short walking bouts <10 s (−21.7, p = 0.001). ConclusionPatients with KOA and KJR showed no significant reduction in number of daily step counts and transfers from sitting to standing position when compared with matched healthy controls. However, the number of short walking bouts was reduced in patients with KOA and by twice as much in patients with KJR. This indicates that KOA and treatment with KJR hardly affect health-related general activity but do affect specific physical activity behaviour potentially indicative of KOA or post-KJR functional limitations. The translational potential of this articleActivity monitoring with an accelerometer-based method gives insights into health-related general activity levels such as total daily steps and specific parameters such as short walking bouts, which may serve as an objective outcome measure in clinical practice.

Cerebral Blood Flow Characteristics Responses Following Acute Aerobic Exercise in Individuals with and without Down Syndrome

Individuals with Down Syndrome (DS) commonly experience low to moderate levels of cognitive impairment and are at a high risk of developing dementia and Alzheimer's diseases (AD). Reduced cerebral blood flow (CBF) and altered CBF characteristics have been observed in the aging population without DS and has shown to have detrimental effects on cerebral microvasculature, which may increase the risk of developing dementia and AD. However, differences in CBF and its characteristics between individuals with and without DS and its response to exercise have not been studied.PurposeTo examine the differences in CBF and its characteristics following a 20‐minute bout of moderate intensity walking in individuals with and without DS.MethodsThirty‐eight young (DS=19, Age=25 yrs) individuals with and without DS participated in this study. Changes in mean middle cerebral artery velocity (mMCAv), mMCAv characteristics (pulsatility index (PI), resistance index (RI)) and hemodynamic variables were measured before, immediately post and 30‐minute post exericse.ResultsBaseline hemodynamics, systolic blood pressure (BP), diastolic BP, mean arterial pressure (MAP), heart rate (HR) and mMCAv were not different between the DS and control group (p&gt;0.05 for all). Neither group showed changes in mMCAv after moderate intensity treadmill walking exercise (p&gt;0.05). However, the DS group exhibited significantly higher PI and RI at all time points when compared to controls (p&lt;0.05 for both).ConclusionsOur results demonstrate that CBF was not altered in individuals with DS at rest and following moderate intensity exercise and was not different from that of controls. However, higher PI and RI in DS group may be associated with reduced distal cerebral perfusion and microvascular damage in individuals with DS. DS (N = 19) Control (N = 19) Baseline Immediate post EX 30‐minute post EX Baseline Immediate post EX 30‐minute post EX SBP (mmHg) 122±14 126±11* 121±13 120±10 130±12* 121±11 DBP (mmHg) 69±9 75±8* 70±9 72±6 81±8* 74±9 MAP (mmHg) 93±10 98±8* 94±9 94±7 103±7* 96±8 mMCAv (cm/s) 64.3±14.9 62.8±13.9 60.8±14.6 69.4±13.1 69.8±14.8 69.6±14.1 PI‡ 0.97±0.14 1.04±0.19 1.02±0.14 0.87±0.12 0.89±0.15 0.86±0.14 RI‡ 0.60±0.05 0.61±0.06 0.61±0.05 0.56±0.05 0.56±0.05 0.55±0.05 Significant group difference, Significant time difference from the baseline. Mean ± SD, Significance level, p &lt; 0.05 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

THE EFFECTS OF BLOOD FLOW RESTRICTION TRAINING ON FUNCTIONAL IMPROVEMENTS IN AN ACTIVE SINGLE SUBJECT WITH PARKINSON DISEASE

Blood flow restriction (BFR) applied during low intensity exercise produces hypertrophy and strength gains equivalent to traditional training. Previous research has shown the positive effects of BFR on younger and older adults. However, the effectiveness of BFR on subjects with Parkinson Disease (PD) has not been investigated. The purpose of the study was to determine the effects of BFR on a recreationally active person with PD in regards to functional improvements and safety. The hypothesis was that BFR training will demonstrate improvements in motor function, gait and endurance, while decreasing symptoms associated with Restless Leg Syndrome (RLS) in a subject with PD. A single subject, B-A design was used. The subject was an active 65-year-old male recreational boxer diagnosed with PD. Baseline data were measured on day one. The intervention (Phase B) consisted of five, two-minute bouts of walking on treadmill with lower extremity BFR cuffs interspersed with 1 minute rest, three times a week for six weeks, at 0 grade incline, and speed of 50 meters/min. The pressure increased from the initial 120 to 160 mmHg at the end of the phase B as per the subject's tolerance. A four-week baseline phase (A) without the BFR intervention followed phase B. The outcome measures which were measured every two weeks over the 10 weeks included: Timed Up and Go Test, 6-Minute Walk Test, 30-Second Chair Stand Test, and the RLS Questionnaire. All outcome measures steadily improved every two weeks during the six week intervention phase and steadily declined when the intervention was removed during the second four week baseline phase according to visual inspection of the graphed data points. The subject enjoyed and tolerated the intervention well without any adverse effects. The results were that BFR training can produce functional improvements, reduce restless leg syndrome symptoms and can be safely utilized with a subject with PD who wishes to maintain his ability to remain recreationally active.

Abstract P286: Walking as a Source of Physical Activity for Cardiovascular Disease Prevention

Introduction: Increasing physical activity among adults at risk for or with cardiovascular disease (CVD) can help prevent and manage disease. Walking may present an opportunity for promoting physical activity among this high risk group. We hypothesized that in US adults the prevalence of self-reported walking would decrease with increasing CVD risk. Methods: Nationally representative data from the 2015 National Health Interview Survey Cancer Control Supplement (N=28,780) were analyzed. Analyses were repeated after excluding those needing assistance with walking (n=2,192). Walking was defined as engaging in at least one 10-minute bout of transportation or leisure walking in the past seven days. Prevalence estimates of walking (any, transportation, and leisure) are reported overall and by presence of risk factors (overweight or obesity and ≥1 of diabetes, high cholesterol, or hypertension) or CVD (myocardial infarction or stroke). Orthogonal polynomial contrasts were used to identify significant trends. Results: Overall, 64.9% (standard error, SE=0.5) of adults reported any walking (TABLE). This prevalence was highest among those with no CVD or risk factors (67.1%, SE=0.5), decreased with increasing number of risk factors (1 risk factor: 64.0%, SE=1.0; 2 risk factors: 60.3%, SE=1.3; 3 risk factors: 54.8%, SE=2.0), and the lowest was among those with CVD (51.9%, SE=1.7). Similar trends were observed for leisure and transportation walking. To ensure differences in prevalence of walking by risk factor or disease status was not due to functional limitations, repeated analyses that excluded those needing assistance with walking observed similar patterns. Conclusions: Prevalence of any and leisure walking decreased as the presence of CVD risk factors increased and was lowest among those with disease. Promoting walking, especially among adults at higher risk, may present an important opportunity for encouraging an active lifestyle for CVD prevention and management.

Measuring Moderate-Intensity Exercise with the Apple Watch: Validation Study.

BackgroundModerate fitness levels and habitual exercise have a protective effect for cardiovascular disease, stroke, type 2 diabetes, and all-cause mortality. The Apple Watch displays exercise completed at an intensity of a brisk walk or above using a green “exercise” ring. However, it is unknown if the exercise ring accurately represents an exercise intensity comparable to that defined as moderate-intensity. In order for health professionals to prescribe exercise intensity with confidence, consumer wearable devices need to be accurate and precise if they are to be used as part of a personalized medicine approach to disease management.ObjectiveThe aim of this study was to examine the validity and reliability of the Apple Watch for measuring moderate-intensity exercise, as defined as 40-59% oxygen consumption reserve (VO2R).MethodsTwenty recreationally active participants completed resting oxygen consumption (VO2rest) and maximal oxygen consumption (VO2 max) tests prior to a series of 5-minute bouts of treadmill walking at increasing speed while wearing an Apple Watch on both wrists, and with oxygen consumption measured continuously. Five-minute exercise bouts were added until the Apple Watch advanced the green “exercise” ring by 5 minutes (defined as the treadmill inflection speed). Validity was examined using a one-sample t-test, with interdevice and intradevice reliability reported as the standardized typical error and intraclass correlation.ResultsThe mean %VO2R at the treadmill inflection speed was 30% (SD 7) for both Apple Watches. There was a large underestimation of moderate-intensity exercise (left hand: mean difference = -10% [95% CI -14 to -7], d=-1.4; right hand: mean difference = -10% [95% CI -13 to -7], d=-1.5) when compared to the criterion of 40% VO2R. Standardized typical errors for %VO2R at the treadmill inflection speed were small to moderate, with intraclass correlations higher within trials compared to between trials.ConclusionsThe Apple Watch threshold for moderate-intensity exercise was lower than the criterion, which would lead to an overestimation of moderate-intensity exercise minutes completed throughout the day.

Objective assessment of physical activity and sedentary behaviour in knee osteoarthritis patients \u2013 beyond daily steps and total sedentary time

BackgroundKnee osteoarthritis patients may become physically inactive due to pain and functional limitations. Whether physical activity exerts a protective or harmful effect depends on the frequency, intensity, time and type (F.I.T.T.). The F.I.T.T. dimensions should therefore be assessed during daily life, which so far has hardly been feasible. Furthermore, physical activity should be assessed within subgroups of patients, as they might experience different activity limitations. Therefore, this study aimed to objectively describe physical activity, by assessing the F.I.T.T. dimensions, and sedentary behaviour of knee osteoarthritis patients during daily life. An additional goal was to determine whether activity events, based on different types and durations of physical activity, were able to discriminate between subgroups of KOA patients based on risk factors.MethodsClinically diagnosed knee osteoarthritis patients (according to American College of Rheumatology criteria) were monitored for 1 week with a tri-axial accelerometer. Furthermore, they performed three functional tests and completed the Knee Osteoarthritis Outcome Score. Physical activity levels were described for knee osteoarthritis patients and compared between subgroups.ResultsSixty-one patients performed 7303 mean level steps, 319 ascending and 312 descending steps and 601 bicycle crank revolutions per day. Most waking hours were spent sedentary (61%), with 4.6 bouts of long duration (> 30 min). Specific events, particularly ascending and descending stairs/slopes, brief walking and sedentary bouts and prolonged walking bouts, varied between subgroups.ConclusionsFrom this sample of KOA patients, the most common form of activity was level walking, although cycling and stair climbing activities occurred frequently, highlighting the relevance of distinguishing between these types of PA. The total active time encompassed a small portion of their waking hours, as they spent most of their time sedentary, which was exacerbated by frequently occurring prolonged bouts.In this study, event-based parameters, such as stair climbing or short bouts of walking or sedentary time, were found more capable of discriminating between subgroups of KOA patients compared to overall levels of PA and sedentary time. Thereby, subtle limitations in physical behaviour of KOA-subgroups were revealed, which might ultimately be targeted in rehabilitation programs.Trial registrationGerman Clinical Trials Registry under ‘DRKS00008735’ at 02.12.2015.

Affective Responses to Acute Bouts of Aerobic Exercise, Mindfulness Meditation, and Combinations of Exercise and Meditation: A Randomized Controlled Intervention.

Single bouts of aerobic exercise and meditation have been shown to induce positive affect. In a novel experimental paradigm, we sought to examine the effects of an acute bout of aerobic exercise and meditation, as well as exercise and meditation combined on affect among young adults. Participants ( N = 110, mean age = 21.4 years) were randomly assigned to walk, meditate, walk then meditate, meditate then walk, or to sit (inactive control). All walking and meditation bouts were 10 minutes in duration. Participants' affect was monitored before and after the intervention using the Exercise Induced Feelings Inventory. Significant group × time interaction effects were observed for three Exercise Induced Feelings Inventory subscales, including revitalization ( p < .001), tranquility ( p = .02), and exhaustion ( p = .03); the group × time interaction for Exercise Induced Feelings Inventory positive engagement was nonsignificant ( p = .16). A single bout of brisk walking or meditation, as well as a combination of walking and meditation, may positively influence affect. There is some evidence to suggest that affective benefits may be greater following meditation or a combination of meditation and walking, when compared with walking alone.

Effects of acute aerobic exercise or meditation on emotional regulation

Effective emotional regulation is critical for overall psychological well-being; as such, it is important to investigate potential methods to optimize emotion regulation abilities. The purpose of this study was to examine the effects of an acute bout of aerobic exercise and meditation on emotional regulation among young adults. Participants (N=63, mean age=21.3yrs) were randomly assigned to stretch (control group, n=21), walk (n=21), or meditate (n=21) for 10-min, after which they were exposed to a film clip (3min) intended to elicit a negative emotional state (e.g., sadness, anger). Participants then viewed 12 International Affective Picture System images validated to elicit a negative valence. Participants' affect (valence and arousal) states were monitored before, during, and after the stretching, walking, and meditation bouts using the Feeling Scale (FS) and Felt Arousal Scale (FAS). Distinct affect was assessed utilizing an affective circumplex measure before and after the stretch/walk/meditation bout, as well as following the film clip and image viewing. A significant group×time interaction effect was present when evaluating circumplex excited: P=0.001 (η2=0.21). Additionally, an interaction effect of meditation and emotional regulation was observed (P=0.009) among those with varying degrees of meditation experience. A 10-min bout of brisk walking and meditation, prior to exposure to a negative emotion cue, did not differentially effect the ability to regulate sadness, anger, or anxiousness when compared to an active stretching control group. Future replicative work addressing this paradigm, which is in support of positive psychology theory, is warranted.

The Effects of Acute Exercise on Cognitive Function: Solomon Experimental Design.

No study has yet evaluated the effects of an acute 5-min bout of exercise (walking) on cognitive function, which was the purpose of our study. We employed a Solomon-4 experimental design, in which 22 young adult participants were included in each group. Participants in two groups (1 and 3) walked on a treadmill for 5min at a self-selected intensity. We assessed cognitive function by means of the Trail Making B test. We observed no difference in cognitive function between the two assessments for the control group (group 2: 42.8 vs. 40.6s), but found a significant effect for adults in group 1 (56.3 vs. 35.7s), whose cognitive function was markedly improved after the 5-min bout of walking. This within-group by between-group interaction (change due to the treatment) was statistically significant (-20.4 vs. -2.2s). A 5-min bout of walking at a self-selected intensity is associated with improved cognitive function. Given our observed interaction effect of the pretest and treatment (walking) on cognitive function, we encourage researchers to investigate the potential additive or synergistic effects of mental training and acute exercise on cognition.

Viewing the Outdoors During Indoor Walking May Yield No Additional Exercise-Induced Affective Benefit

Objective: We examined the experimental effects of two different indoor environmental conditions (blind up [visible view of the outdoors] or blinds down) during an acute bout of walking on participants’ affect. Methods: Participants (N= 30, mean age = 20.5 yrs) completed a 15-min walking bout on two different days – one when participants walked in front of windows with a view of the outdoors (including natural sights such as trees, flowers, etc.) and one when participants walked in front of the same windows with the blinds down and no outside view. We counter-balanced the order of these conditions, and treadmill speed was matched across the two visits. Results: There were no significant differences in affect change scores (post-walk minus baseline) between outdoor view or no outdoor view conditions. Both acute bouts of walking demonstrated positive affective changes. Conclusion: While this slight modification to the environment did not appear to alter exercise-induced hedonic responses during moderate-intensity walking, future research should continue to investigate any effects of other modifications and the extent to which biological, psychological and/or environmental mechanisms may or may not interact.

Temporal Effects of Acute Walking Exercise on Learning and Memory Function.

To evaluate the temporal effects of acute exercise on episodic memory. A quasi-experimental study. Eighty-eight college students (N = 22 per group). 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. 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. Regarding learning, the interaction of groups × trial was marginally statistically significant ( F12,332 = 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). Engaging in a 15-minute bout of moderate-intensity walking before a learning task was effective in influencing long-term episodic memory.

Postprandial walking reduces glucose levels in women with gestational diabetes mellitus.

The purpose of this study was to investigate blood glucose changes, as measured by a continuous glucose monitoring system, that occur in women with gestational diabetes mellitus (GDM) following an acute bout of moderate-intensity walking after consuming a high-carbohydrate/low-fat meal. This study found that moderate-intensity walking induced greater postprandial glucose control compared with sedentary activity and it appears that moderate-intensity activity may be used to reduce postprandial glucose levels in women with GDM.

Different Patterns of Walking and Postprandial Triglycerides in Older Women.

ABSTRACTPurposeAlthough a single bout of continuous exercise (≥30 min) reduces postprandial triglyceride (TG), little evidence is available regarding the effect of multiple short (≤10 min) bouts of exercise on postprandial TG in individuals at increased risk for cardiovascular diseases. This study compared the effects of different patterns of walking on postprandial TG in postmenopausal, older women with hypertriglyceridemia.MethodsTwelve inactive women (mean age ± SD, 71 ± 5 yr) with hypertriglyceridemia (fasting TG ≥1.70 mmol·L−1) completed three, 1-d laboratory-based trials in a random order: 1) control, 2) continuous walking, and 3) multiple short bouts of walking. On the control trial, participants sat in a chair for 8 h. For the walking trials, participants walked briskly in either one 30-min bout in the morning (0900–0930 h) or twenty 90-s bouts over 8 h. Except for walking, both exercise trials mimicked the control trial. In each trial, participants consumed a standardized breakfast (0800 h) and lunch (1100 h). Venous blood samples were collected in the fasted state and at 2, 4, 6, and 8 h after breakfast.ResultsThe serum TG incremental area under the curve was 35% and 33% lower on the continuous and multiple short bouts of walking trials than that on the control trial (8.2 ± 3.1 vs 8.5 ± 5.4 vs 12.7 ± 5.8 mmol per 8 h·L−1, respectively; main effect of trial: effect size = 0.459, P = 0.001).ConclusionsAccumulating walking in short bouts limits postprandial TG in at-risk, inactive older women with fasting hypertriglyceridemia.

Differential Experimental Effects of a Short Bout of Walking, Meditation, or Combination of Walking and Meditation on State Anxiety Among Young Adults.

Single bouts of aerobic exercise and meditation have been shown to improve anxiety states. Yet to be evaluated in the literature, we sought to examine the effects of a single, short bout of aerobic exercise or meditation, as well as exercise and meditation combined on state anxiety among young adults. Randomized controlled trial. University. Participants (N = 110, mean age = 21.4 years) were randomly assigned to walk, meditate, walk then meditate, meditate then walk, or to sit (inactive control). All walking and meditation bouts were 10 minutes in duration. Participants' state anxiety was monitored before and after the intervention using the State Trait Anxiety Inventory questionnaire. Significant group × time interaction effects were observed ( P = .01). Post hoc paired t tests revealed that state anxiety significantly decreased from baseline to postintervention in the meditation ( P = .002), meditation then walk ( P = .002), and walk then meditation ( P = .03) groups but not the walk ( P = .75) or control ( P = .45) groups. Meditation (vs a brisk walk) may be a preferred method of attenuating anxiety symptomology. Individuals desiring the health benefits associated with aerobic exercise may achieve additional anxiolytic benefits if they employ a brief meditation session before or after exercising.

The impact of acute bouts of interval and continuous walking on energy-intake and appetite regulation in subjects with type 2 diabetes.

In healthy subjects, it has been suggested that exercise may acutely suppress energy‐intake and appetite, with peak intensity being an important determinant for this effect. In subjects with type 2 diabetes (T2D), the effect of exercise on appetite‐related variables is, however, virtually unknown. We aimed to assess the effects of two exercise interventions, differing with regards to peak intensity, on energy‐intake, satiety and appetite‐related hormones in subjects with T2D. Thirteen subjects with T2D completed three 60‐min interventions with continuous measurement of oxygen consumption in a randomized and counterbalanced order: (1) Control, (2) Continuous walking (CW; intended 73% of VO 2peak), (3) Interval‐walking (IW; repeated cycles of 3 min slow [54% of VO 2peak] and 3 min fast walking [89% of VO 2peak]). Forty‐five minutes after completion of the intervention, a 3‐h liquid mixed meal tolerance test (MMTT, 450 kcal) with regular satiety assessments and blood samples for appetite‐related hormones commenced. An ad libitum meal was served after the MMTT, with subsequent calculation of energy‐intake. Moreover, free‐living diet records were completed for the following ~32 h. Exercise interventions were well‐matched for mean oxygen consumption (CW = 77 ± 2% of VO 2peak; IW = 76 ± 1% of VO 2peak, P > 0.05). No differences in appetite‐related hormones or energy‐intake were found (P > 0.05 for all comparisons). IW increased fullness compared to Control shortly after the intervention (P < 0.05) and tended to reduce hunger 2 h into the MMTT compared to CW and Control (P < 0.10). In conclusion, a single exercise session does not affect energy‐intake during the following ~4–36 h in subjects with T2D. However, satiety may be affected up to ~3 h after the exercise session, dependent on peak intensity.

Validating Walkability Models Using Volunteered Mobile Phone Data ( breakout presentation )

Walkshed modelling is a popular way of estimating where people are likely to walk when presented with a network of streets and sidewalks. One approach describes walksheds as regions accessible on foot from a point of origin by taking into account the topology of streets in a neighbourhood. While these models are useful explorations of urban form, they are limited by describing only the potential for walking. They are not representations of where people actually walk. The location history collected by mobile phones presents a new opportunity to validate these models using high spatial and temporal resolution data describing actual movement. Here we demonstrate applications of volunteered geographic information to probe walking behaviour, drawing upon a pilot study of University of Calgary students in 2016. Using approximately 10,000,000 GPS points from 30 university students (2013 to 2016; 51 person-years of data) we ask where, how far, and how often our participants walked over a three-year period. We also introduce a continuous modelling approach that describes the potential for urban form to limit walking (“the walk warp”) and test this against evidence of actual movement. We identified 593 walking bouts (1-5km/h, lasting at least 6 minutes), a number that was exceeded by vehicular bouts (2423; > 5 km/h lasting at least 6 minutes). Using the primary residences of our participants as points of origin, we found that an individual’s walking behaviour was correlated with the walk–warp of their neighbourhood. Volunteered mobile phone data are cost-effective and easy to collect. They provide an accessible means to measure walking behaviour, and as we have demonstrated in our pilot study, can be applied to test theoretical assumptions about the walkability of neighbourhoods.

Fitness Moderates Glycemic Responses to Sitting and Light Activity Breaks.

This study aimed to experimentally determine whether cardiorespiratory fitness (CRF) modifies postprandial glycemia during prolonged sitting and investigated the potentially blunting influence this may have on the benefits of interrupting postprandial sitting time with light activity breaks. Thirty-four adults (18 women; 16 men; mean ± SD age, 40 ± 9 yr, body mass index, 24.5 ± 3 kg·m) undertook two 7.5-h experimental conditions in a randomized order: 1) Prolonged sitting; 2) Sitting interspersed with 5 min light walking bouts every 30 min. Blood samples were obtained while fasting and postprandially after ingestion of two identical meals. Incremental area under the curve (iAUC) was calculated for glucose and insulin throughout experimental conditions. Maximal exercise testing quantified peak oxygen consumption (V˙O2 peak) as a measure of CRF. A repeated-measures ANOVA investigated whether V˙O2 peak modified glucose and insulin iAUC between conditions. Breaking sedentary time with light walking breaks reduced blood glucose iAUC from 3.89 ± 0.7 to 2.51 ± 0.7 mmol·L·h (P = 0.015) and insulin iAUC from 241 ± 46 to 156 ± 24 mU·L·h (P = 0.013) after adjustment for V˙O2 peak and sex. A significant interaction between treatment response and V˙O2 peak was observed for glucose (P = 0.035), but not insulin (P = 0.062), whereby the treatment effect reduced with higher CRF. Average blood glucose iAUC responses for a man at the 25th centile of CRF within our cohort (42.5 mL·kg·min) went from 5.80 to 2.98 mmol·L·h during the prolonged sitting and light walking break conditions respectively, whereas average responses for a man at the 75th centile of CRF (60.5 mL·kg·min) went from 1.99 to 1.78 mmol·L·h. Similar trends were observed for women. Individuals with low CRF gained the most metabolic benefit from breaking prolonged sitting with regular bouts of light walking.

Intermittent Standing but not a Moderate Exercise Bout Reduces Postprandial Glycemia.

This study aimed to determine whether minimum recommended moderate-to-vigorous physical activity (MVPA; 30-min bout of continuous moderate-intensity walking) is sufficient to counteract the detrimental effects of prolonged sitting on postprandial metabolism and if there are any effects of breaking up sitting with intermittent standing when achieving minimum recommended MVPA. Fourteen (n = 14) physically inactive healthy adult males underwent four intrahospital 27-h interventions: 9-h continuous sitting (SIT), 15-min standing bouts every 30 min during the 9-h sitting (STAND), 30-min moderate-intensity walking bout followed by 8.5 h of sitting (MVPA), and 30-min moderate-intensity walking bout followed by 15-min standing bouts every 30 min during 8.5 h of sitting (MVPA + STAND). Three standardized meals on intervention day (day 1) and breakfast the following day (day 2) were served. Cumulative postprandial glucose response (incremental area under the curve) was lower in STAND versus SIT (↓27%, P = 0.04, effect size [ES] = -0.7) because of decreases in postprandial glucose after breakfast on day 1 (STAND vs SIT: ↓40%, P = 0.01, ES = -0.7) and day 2 (STAND vs SIT: ↓33%, P = 0.06, ES = -0.6). STAND did not affect postprandial insulin responses. Cumulative postprandial insulin response was lower in MVPA versus SIT (↓18%, P = 0.03, ES = -0.3) and MVPA + STAND versus SIT (↓26%, P = 0.02, ES = -0.4) because of expected exercise-induced decreases in postprandial insulin after breakfast on day 1 only (MVPA vs SIT: ↓36%, P = 0.003, ES = -0.7; MVPA + STAND vs SIT: ↓43%, P = 0.0001, ES = -0.8). Breaking up prolonged sitting with nonambulatory standing across 9 h acutely reduced postprandial glycemic response during and the day after the intervention independent of insulin levels, whereas a 30-min MVPA bout did not.

Can Tai Chi training impact fractal stride time dynamics, an index of gait health, in older adults? Cross-sectional and randomized trial studies.

PurposeTo determine if Tai Chi (TC) has an impact on long-range correlations and fractal-like scaling in gait stride time dynamics, previously shown to be associated with aging, neurodegenerative disease, and fall risk.MethodsUsing Detrended Fluctuation Analysis (DFA), this study evaluated the impact of TC mind-body exercise training on stride time dynamics assessed during 10 minute bouts of overground walking. A hybrid study design investigated long-term effects of TC via a cross-sectional comparison of 27 TC experts (24.5 ± 11.8 yrs experience) and 60 age- and gender matched TC-naïve older adults (50–70 yrs). Shorter-term effects of TC were assessed by randomly allocating TC-naïve participants to either 6 months of TC training or to a waitlist control. The alpha (α) long-range scaling coefficient derived from DFA and gait speed were evaluated as outcomes.ResultsCross-sectional comparisons using confounder adjusted linear models suggest that TC experts exhibited significantly greater long-range scaling of gait stride time dynamics compared with TC-naïve adults. Longitudinal random-slopes with shared baseline models accounting for multiple confounders suggest that the effects of shorter-term TC training on gait dynamics were not statistically significant, but trended in the same direction as longer-term effects although effect sizes were very small. In contrast, gait speed was unaffected in both cross-sectional and longitudinal comparisons.ConclusionThese preliminary findings suggest that fractal-like measures of gait health may be sufficiently precise to capture the positive effects of exercise in the form of Tai Chi, thus warranting further investigation. These results motivate larger and longer-duration trials, in both healthy and health-challenged populations, to further evaluate the potential of Tai Chi to restore age-related declines in gait dynamics.Trial registrationThe randomized trial component of this study was registered at ClinicalTrials.gov (NCT01340365).

Differences in behavior, time, location, and built environment between objectively measured utilitarian and recreational walking

ObjectivesUtilitarian and recreational walking both contribute to physical activity. Yet walking for these two purposes may be different behaviors. We sought to provide operational definitions of utilitarian and recreational walking and to objectively measure their behavioral, spatial, and temporal differences in order to inform transportation and public health policies and interventions. MethodsData were collected 2008–2009 from 651 Seattle-King County residents, wearing an accelerometer and a GPS unit, and filling-in a travel diary for 7days. Walking activity bouts were classified as utilitarian or recreational based on whether walking had a destination or not. Differences between the two walking purposes were analyzed, adjusting for the nested structure of walking activity within participants. ResultsOf the 4905 observed walking bouts, 87.4% were utilitarian and 12.6% recreational walking. Utilitarian walking bouts were 45% shorter in duration (−12.1min) and 9% faster in speed (+0.3km/h) than recreational walking bouts. Recreational walking occurred more frequently in the home neighborhood and was not associated with recreational land uses. Utilitarian walking occurred in areas having higher residential, employment, and street density, lower residential property value, higher area percentage of mixed-use neighborhood destinations, lower percentage of parks/trails, and lower average topographic slope than recreational walking. ConclusionUtilitarian and recreational walking are substantially different in terms of frequency, speed, duration, location, and related built environment. Policies that promote walking should adopt type-specific strategies. The high occurrence of recreational walking near home highlights the importance of the home neighborhood for this activity.