Sedentary Control Condition Research Articles

Effect Of Frequent Daily Walking Bouts On Sedentary Time And Self-perceived Fatigue In Free-living Adults

PURPOSE: Breaking up sedentary time with frequent short bouts of activity has been suggested as a novel strategy to reduce sedentary behaviors, but whether this strategy will be effective at reducing sedentary time in free-living conditions is unknown. In this pilot study, objective measures of physical activity and self-reported measures of fatigue and vigor were compared over 3-days among the following free-living conditions (1) microburst activity (MICRO: 5-min of brisk walking every hour for 9 hours), (2) one 45-min bout of brisk walking (ONE), and (3) a sedentary control condition (SED). METHODS: Eighteen sedentary overweight adults (12F/6 M, mean±SD; age=32.2± 6.1 yo, BMI= 30.8±2.5 kg/m2) completed each condition (MICRO, ONE, SED) in a randomized crossover study. The percentage of time spent in sedentary, light-intensity (LPA) and moderate-to-vigorous intensity physical activity (MVPA) were measured by accelerometry (ActiGraph GT3X+). At the end of each day, participants self-reported their level of fatigue and vigor using visual analog scales (VAS). RESULTS: Both MICRO (7.5±3.3%, p=0.04) and ONE (9.5 ± 3.3%, p < 0.0001) increased the percentage of time spent in MVPA during waking hours compared to SED (5.2±2.4%). However, MVPA decreased between the first (10.1±2.5%) and the third day (8.2±2.5%, p=0.02) of ONE, while no changes occurred in MICRO. ONE (79.3 ± 5.9%, p<0.0001), but not MICRO (83.1±5.4%) reduced the percentage of time spent sedentary during waking compared to SED (84.4±5.7%). The fact that LPA was lower with MICRO (10.6±4.1%) than with ONE (12.9±5.4%, p=0.03) suggests a spontaneous displacement from LPA towards sedentary time. Participants reported feeling less “worn out” (34.3±25.9 vs. 42.8±26.1, p = 0.04), “bushed” (33.8±25 vs. 41.6±24.1, p=0.05), and had a lower desire to close their eyes (37.3±27.5 vs. 44.1±26.6, p=0.05) and lie down (39.5±28.0 vs. 47.6±27.7, p=0.055) during MICRO compared to ONE conditions. CONCLUSIONS: Performing a continuous bout of brisk walking per day seems to be more potent at increasing MVPA and reducing time spent sitting, however, the effects may not be long lasting. Small lifestyle changes such as those induced by microbouts of activity may be easier to implement in at-risk populations. Long term studies are needed to confirm this hypothesis.

Acute effects of outdoor physical activity on affect and psychological well-being in depressed patients – A preliminary study

IntroductionPhysical activity (PA) is well established in the treatment of people with depressive symptoms. Most of this activity is done in an indoor setting. There is growing evidence that PA outdoors shows larger positive effects on affective states than PA indoors. The aim of the present study was to compare the affective experience of an acute outdoor exercise bout with indoor and sedentary equivalents for individuals with clinical depression. Method14 in-patients with mild to moderate depression were recruited during treatment in a mental health center. In a within-subjects experimental study, all participants completed three 60-min sessions: a sedentary control condition (SC), an indoor PA condition (IC), and an outdoor PA condition (OC). Mood, valence and activation were assessed throughout each session using the Mood Survey Scale (MSS), Feeling Scale and Felt Arousal Scale. ResultsConcerning the MSS subscales, whilst patients in the SC exhibited minimal changes, significantly lower “excitement” scores and higher “activation” scores were reported following the OC. Affective activation also differed significantly between OC and IC. ConclusionA single outdoor exercise bout showed greater affective improvements compared to indoor and sedentary equivalents for self-reported excitement and activation. As patients felt more active, an outdoor setting might be useful in overcoming listlessness during depression treatment. Due to methodological limitations associated with the pragmatic nature of the trial, findings must be interpreted with caution. Further trials should focus on wider feasibility and acceptability of outdoor exercise in depressive patients.

Exercise leads to the re-emergence of the cholinergic/nestin neuronal phenotype within the medial septum/diagonal band and subsequent rescue of both hippocampal ACh efflux and spatial behavior

Exercise has been shown to improve cognitive functioning in a range of species, presumably through an increase in neurotrophins throughout the brain, but in particular the hippocampus. The current study assessed the ability of exercise to restore septohippocampal cholinergic functioning in the pyrithiamine-induced thiamine deficiency (PTD) rat model of the amnestic disorder Korsakoff Syndrome. After voluntary wheel running or sedentary control conditions (stationary wheel attached to the home cage), PTD and control rats were behaviorally tested with concurrent in vivo microdialysis, at one of two time points: 24-h or 2-weeks post-exercise. It was found that only after the 2-week adaption period did exercise lead to an interrelated sequence of events in PTD rats that included: (1) restored spatial working memory; (2) rescued behaviorally-stimulated hippocampal acetylcholine efflux; and (3) within the medial septum/diagonal band, the re-emergence of the cholinergic (choline acetyltransferase [ChAT+]) phenotype, with the greatest change occurring in the ChAT+/nestin+ neurons. Furthermore, in control rats, exercise followed by a 2-week adaption period improved hippocampal acetylcholine efflux and increased the number of neurons co-expressing the ChAT and nestin phenotype. These findings demonstrate a novel mechanism by which exercise can modulate the mature cholinergic/nestin neuronal phenotype leading to improved neurotransmitter function as well as enhanced learning and memory.

Long-term mild exercise training enhances hippocampus-dependent memory in rats.

Although exercise training improves hippocampus-related cognition, the optimum exercise intensity is still disputed. Based on the lactate threshold (LT, approximately 20 m/min on treadmill) of rats, we have shown that 2 weeks of training with stress-free mild exercise (ME, <LT), but not intense exercise (IE, >LT), comprising exercise stress, promotes adult hippocampal neurogenesis (Okamoto et al., PNAS, 2012), a potential substrate for memory improvement. These results led us to postulate that long-term ME, but not IE, training leads to improved hippocampal function as assessed with a Morris water maze (MWM) task. To test this hypothesis, we investigated the changes in physiological stress levels and MWM task performance in rats assigned to 6 weeks of sedentary control (CONT), ME-training or IE-training conditions. Results showed that, compared to the other conditions, only IE causes general adaptive syndrome (GAS), including adrenal hypertrophy, thymic atrophy and hypercorticosteronemia. In the MWM, ME led to enhanced memory, but not learning, compared with CONT, while IE produced no change in either capacity, probably due to GAS. These findings support the hypothesis that 6 weeks of continuous ME training leads to enhanced hippocampus-related memory, which may have implications for both healthy adults and subjects with low physical capacity.

Effect of Moderate-Intensity Exercise Versus Activities of Daily Living on 24-Hour Blood Glucose Homeostasis in Male Patients With Type 2 Diabetes

OBJECTIVETo investigate the impact of activities of daily living (ADL) versus moderate-intensity endurance-type exercise on 24-h glycemic control in patients with type 2 diabetes.RESEARCH DESIGN AND METHODSTwenty males with type 2 diabetes participated in a randomized crossover study consisting of three experimental periods of 3 days each. Subjects were studied under sedentary control conditions, and under conditions in which prolonged sedentary time was reduced either by three 15-min bouts of ADL (postmeal strolling, ∼3 METs) or by a single 45-min bout of moderate-intensity endurance-type exercise (∼6 METs). Blood glucose concentrations were assessed by continuous glucose monitoring, and plasma insulin concentrations were determined in frequently sampled venous blood samples.RESULTSHyperglycemia (glucose >10 mmol/L) was experienced for 6 h 51 min ±1 h 4 min per day during the sedentary control condition and was significantly reduced by exercise (4 h 47 min ± 1 h 2 min; P < 0.001), but not by ADL (6 h 2 min ± 1 h 16 min; P = 0.67). The cumulative glucose incremental areas under the curve (AUCs) of breakfast, lunch, and dinner were, respectively, 35 ± 5% (P < 0.001) and 17 ± 6% (P < 0.05) lower during the exercise and ADL conditions compared with the sedentary condition. The insulin incremental AUCs were, respectively, 33 ± 4% (P < 0.001) and 17 ± 5% (P < 0.05) lower during the exercise and ADL conditions compared with the sedentary condition.CONCLUSIONSWhen matched for total duration, moderate-intensity endurance-type exercise represents a more effective strategy to improve daily blood glucose homeostasis than repeated bouts of ADL. Nevertheless, the introduction of repeated bouts of ADL during prolonged sedentary behavior forms a valuable strategy to improve postprandial glucose handling in patients with type 2 diabetes.

Positive impact of Tai Chi Chuan participation on biopsychosocial quality of life compared to exercise and sedentary controls: a cross-sectional survey

Tai Chi Chuan (TCC) is a traditional Chinese medicine practice and martial art with biopsychosocial aspects. This study aimed to examine the impact of participation in TCC on multiple domains of Quality of Life (QoL) and to assess the involvement of the psychological factors of self-efficacy, Locus of Control (LoC) and Hope in these effects. A total of 68 participants from the general community (13 males and 55 females) aged between 18 and 68 (M=43.55 years) and not currently suffering from a mental or physical illness took part in the study. It was found that TCC participants, as a group, scored significantly better than those in sedentary (book club) and active (gym exercise) control conditions on Psychological and Physical QoL, and that the Physical QoL benefits of TCC continue to accrue with years of practice. The three psychological factors were shown to variously mediate (self-efficacy) and moderate (internal LoC and Hope) this latter relationship. Whilst the results bear limitations (in particular small sample sizes), it is hoped that these findings will encourage further research into TCC, and consideration of TCC as part of the range of treatment options available in community-based mental and physical health management.

A comparison of low- and high-impact forced exercise: Effects of training paradigm on learning and memory

In this study we compared two types of forced exercise—a low impact paradigm to minimize stress, which included speeds up to 10m/min and a stressful high impact paradigm, with speeds up to 21m/min. 150 male C57BL/6J mice were randomly assigned to the low impact, high impact, or sedentary control conditions and were tested on the rotorod and Morris water maze (MWM) as indices of motor learning and spatial memory. We found that 5weeks of stressful high speed forced exercise led to significant improvement in rotorod performance, as high impact runners outperformed both low impact runners and controls at 15 and 25rpm speeds. These differences were the result of improved physical fitness due to exercise and likely do not reflect enhanced learning in these mice. In the MWM, 5weeks of stressful high impact exercise led to significant impairment in spatial memory acquisition compared to low impact runners and controls. Low impact exercise for 10weeks significantly improved retention of spatial memory compared to high impact exercise. Results suggested that these two paradigms produced different effects of forced exercise on learning and memory. The low impact paradigm led to some improvements, whereas the stressful high impact program caused significant impairment. Comparison of these two paradigms begins to address the window between the beneficial and detrimental effects of forced exercise, and have suggested a boundary of exercise intensity that leads to impairment in learning.

Effects of a Single Exercise Bout on Insulin Sensitivity in Black and White Individuals

Previous research suggests non-Hispanic blacks (blacks) are more insulin resistant than non-Hispanic whites (whites). Physical activity can play an important role in reducing insulin resistance. However, it is unknown whether racial differences exist in response to exercise. Therefore, the purpose of this study was to compare metabolic responses to a single bout of exercise in blacks and age-, sex-, and body mass index-matched whites. Whole-body insulin sensitivity, glucose storage, glucose oxidation, and respiratory exchange ratio (RER) were assessed during a hyperinsulinemic-euglycemic clamp in normoglycemic blacks (n = 11) and whites (n = 10). Outcome measures were evaluated in a sedentary control condition and 12 h after treadmill walking at 75% of maximal heart rate for 75 min. In the control condition, there were no differences in insulin sensitivity between blacks and whites (P = 0.54). During the clamp, glucose oxidation and insulin-stimulated RER values were significantly higher in blacks compared with whites (P = 0.04 and P < 0.01, respectively). Despite similar RER values during exercise, RER values at 60, 90, and 120 min after exercise in blacks were also significantly higher compared with whites (P < 0.05). After exercise, there were no significant improvements in insulin sensitivity (P = 0.57) or glucose storage (P = 0.42) in blacks or whites; however, glucose oxidation was significantly lower in both racial groups (P < 0.05). These data suggest that insulin sensitivity is similar in blacks and age-, sex-, and body mass index-matched whites, but the glucose disposal pathways (storage vs. oxidation) are somewhat different. Compared with whites, blacks appear to have a greater capacity to increase glucose oxidation immediately after exercise and during insulin stimulation.

Aerobic exercise intensity and time of stressor administration influence cardiovascular responses to psychological stress

This study examined cardiovascular responses as a function of time following exercise in which participants were exposed to a laboratory stressor. Ninety (42 women) young (18-35 years old) nonsmoking normotensive participants engaged in 30 min of high and low intensity (75-80% and 50-55% VO(2) max) aerobic exercise and a sedentary control condition. Participants were randomly assigned to a laboratory stressor 5, 30, or 60 min following the exercise bout. Results indicate that low and high intensity exercise significantly reduce heart rate (HR) and systolic and diastolic blood pressure reactivity and HR recovery values. An inverse relationship between intensity of exercise and subsequent cardiovascular reactivity was found. These findings suggest attenuated stress responses following acute exercise depend both on exercise intensity and the time of exposure to psychological stress following exercise.

Parasympathetic Rebound and Time Of Stressor Administration Influence Psychophysiological Stress Responses Following Acute Exercise

Despite the anecdotal claims that exercise is effective in alleviating stress, the scientific community has been much more reluctant to make such claims due to issues regarding the nature of the relationship between exercise and stress, including the time course of stress-induced cardiovascular changes following exercise as well as plausible mechanisms underlying the effects. PURPOSE To determine the time course of cardiovascular reactivity and recovery from mental arithmetic following acute aerobic exercise. A related purpose was to examine the role of the autonomic nervous system (ANS), using low and high frequency components of heart rate (HR) variability, as a contributing mechanism underlying cardiovascular responses to stress following exercise. METHODS Ninety (48 male; 42 female) participants initially completed a maximal treadmill test for the determination of maximal oxygen consumption. The effects of 30 min of high- and low-intensity (i.e., 75–80% & 50–55% VO2 max, respectively) aerobic exercise were compared to the effects of a 30 min sedentary control condition on cardiovascular responses to a 6 min mental arithmetic challenge administered at 5, 30, or 60 min post exercise. Measures of HR, HR variability, systolic blood pressure, and diastolic blood pressure were assessed during baseline, stress, and recovery periods. Participants also completed measures of state anxiety, affect, and perceived difficulty before and following the stressor. RESULTS Both low- and high-intensity exercise resulted in significantly reduced stress reactivity and recovery following exercise. Furthermore, high-intensity exercise was more effective at reducing cardiovascular reactivity and enhancing recovery when the stressor was administered at 5, 30, and 60 min post-exercise. CONCLUSION The results indicated that attenuated stress responses following acute exercise depend both on exercise intensity and time of exposure to psychological stress. The results also demonstrated greater cardiac vagal tone following exercise that persisted during exposure to the laboratory stressor, suggesting that parasympathetic rebound may be a viable mechanism underlying exercise-induced reductions in cardiovascular responses to stress.

Effect of estradiol and exercise on lymphocyte proliferation responses in female mice

Many North American women are encouraged to take estrogen replacement therapy and to begin (or continue) physical activity during the postmenopausal years. This study investigated the effect of estradiol exposure and physical exercise on lymphocyte proliferation responses to T and B cell mitogens in female mice. Sixty C57BL/6 mice were randomized to hormone and exercise treatment conditions: hormone treatment consisted of estradiol in vivo (71.4 μg estradiol per day for 21 days) or placebo pellet following bilateral ovariectomy, or surgical sham (mice were not ovariectomized). Exercise consisted of a single forced treadmill run (26 m/min, 6° slope, 90 min) or a sedentary control condition. Outcomes were thymic and splenic lymphocyte proliferation responses to the mitogens concanavalin A (ConA, 1.0 and 5.0 μg/mL concentrations) and lipopolysaccharide (LPS, 0.5, 1.0, and 2.0 μg/mL concentrations). In the thymus, there was a significant reduction of proliferation to ConA in the Ovx + E2 animals relative to the other conditions at both concentrations of mitogen. At 1.0 μg/mL concentration, there was a significant interaction of hormone and exercise treatments. Sham (control) mice given exercise had a higher proliferation response relative to sedentary counterparts, whereas E2 mice did not differ in proliferation responses, irrespective of exercise condition. In the spleen, exposure to high concentrations of estradiol was associated with reduced proliferation responses to both mitogens; there were, however, no main or interaction effects of exercise. These results suggest that high levels of estradiol exposure following ovariectomy in mice significantly reduces lymphocyte blastogenesis responses, and that thymic immunomodulation after acute exercise is masked by the hormonal effect.

Associations of lecithin: cholesterol acyltransferase (LCAT) mass concentrations with exercise, weight loss, and plasma lipoprotein subfraction concentrations in men

The relationships between plasma lecithin: cholesterol acyltransferase (LCAT) mass concentrations and lipids, apolipoprotein, and lipoprotein subfraction concentrations were studied in men assigned at random to a one-year exercise program ( n = 48) and to a sedentary control condition ( n = 31). Exercise training did not significantly affect mean concentrations of LCAT-mass. Moreover changes in LCAT within the exercise group were unrelated to distance run and weight loss. The baseline data and the one-year change data showed consistent positive correlations between LCAT concentrations and total cholesterol, low density lipoprotein cholesterol, very low density lipoprotein cholesterol, and apolipoprotein B concentrations, and consistently weak correlations between LCAT concentrations and high density lipoprotein (HDL)-cholesterol, HDL 2, and apolipoprotein A-I concentrations. The strong correlation between LCAT and total cholesterol may account for LCAT's relationships with lipoprotein subfractions, apolipoprotein B and other lipoprotein cholesterol concentrations.