Resistance Exercise Breaks Improve Ratings of Discomfort and Sleepiness in College Students.

Background: Emerging research suggests using resistance exercises to interrupt prolonged sitting may increase physical activity and reduce fatigue, sleepiness, and muscular discomfort, yet it is unclear if these improvements occur in college students. Methods: Twenty-four students (age 23.1 ± 3.4 years, BMI 27.4 ±  5.0 kg∙m-2) completed two 7-day assessments of discomfort, physical fatigue, mental fatigue, and sleepiness while wearing an ActivPAL. Each week (CON vs REX) followed normal activities while completing assessments in the morning (M), mid-day (MD), and evening (E). During REX, hourly resistance exercise breaks (1 exercise per break, 8 breaks per day) for 2 sets of 15 repetitions. Paired t-tests evaluated difference in physical activity variables. Repeated measures ANOVA (0 between, 3 within) evaluated differences in discomfort, physical fatigue, mental fatigue, and sleepiness variables across treatment (CON vs. REX). Results: Comparison of physical activity resulted in no statistical significance between treatments for all outcomes (p ≥ 0.05). A main effect for treatment was observed for overall discomfort (CON: 2.97, REX: 1.72; p = .042) and for sleepiness (CON: 4.38, REX: 3.89; p = .011). Conclusion: Hourly simple resistance breaks resulted in no compensation in steps or sedentary time while reducing muscular discomfort and sleepiness in a relatively healthy and active population.

The impact of the covid-19 pandemic on lifestyle behaviors in U.S. college students.

OBJECTIVE: To investigate COVID-19's impact on college student health behaviors. PARTICIPANTS: 189 college students. METHODS: Participants completed an online survey on behaviors relating to sleep, sedentary activities, and physical activity before and during the COVID-19 pandemic. Comparisons utilized Students' dependent t-test or Wilcoxon signed-rank tests. RESULTS: There was an increase in time to fall asleep (before: 23.4 ± 18.0 vs. during: 42.8 ± 44.3 min·day-1, p < 0.001), time spent in bed (before: 7.8 ± 1.5 vs. during: 8.5 ± 1.5 hr·day-1, p < 0.001), as well as shifts in later bed and awake time (p < 0.001). Total sedentary time increased during the pandemic (before: 9.0 ± 3.8 vs. during: 9.9 ± 4.1 hr·day-1, p = 0.016); and time spent using a TV, computer, or phone (before: 3.1 ± 1.9 vs. during: 4.2 ± 2.3 hr·day-1, p < 0.001). There was a significant decrease in moderate-vigorous activity (before: 123.8 ± 96.0 vs. during: 108.9 ± 75.5 min·week-1, p = 0.028) and resistance training days (before: 2.4 ± 2.1 vs. during: 1.7 ± 2.1 days·week-1, p < 0.001). CONCLUSIONS: COVID-19 negatively influenced health behaviors in college students.

Overall and repeated measures agreement between brachial-femoral and carotid-femoral measures of pulse wave velocity in young and healthy individuals.

BACKGROUND: Carotid-femoral pulse-wave velocity (cfPWV) is the gold standard measure of arterial stiffness and independently predicts cardiovascular disease. However, obtaining cfPWV requires technical precision and can be difficult in some populations. Brachial-femoral PWV (bfPWV) is a simpler alternative, but there is limited research comparing the two measures. For physiological studies, it is important to know how well the measures agree at rest, and to what extent changes in the measures correspond after perturbation. OBJECTIVE: To assess the overall and repeated measures agreement between cfPWV and bfPWV. METHODS: cfPWV and bfPWV were measured in the supine and seated positions, both before and after a 3-h bout of prolonged sitting. The intraclass correlation coefficient (ICC) for overall agreement was calculated using the random variance components from linear mixed-model regression. Repeated measures agreement (change in cfPWV vs. change in bfPWV) was calculated using repeated measures correlation. RESULTS: Complete data from 18 subjects (22.6 ± 3.1 years old, 33% female) were included in the analysis. There was strong (ICC ≥ 0.70) overall agreement (ICC, 0.75; 95% CI, 0.60-0.85) and very strong (ICC ≥ 0.90) repeated measures agreement (ICC, 0.90; 95% CI, 0.84-0.94) between cfPWV and bfPWV. DISCUSSION: The current findings indicate strong overall agreement and very strong repeated measures agreement between bfPWV and cfPWV. bfPWV is a user-friendly alternative method that agrees with cfPWV-based assessments of central arterial stiffness.

Acute and Chronic Citrulline Malate Supplementation on Muscle Contractile Properties and Fatigue Rate of the Quadriceps.

This study compared the acute and chronic impact of citrulline malate (CM) supplementation on muscle contractile properties and fatigue rate of the quadriceps. Eighteen recreationally trained males consumed both a placebo (PL) and CM treatment for two separate dosing periods. The first experimental testing session for each dosing period was considered the baseline day, the second session the acute day, and the third session the chronic day, which followed seven consecutive days of supplementation. All testing sessions included exercising on a cycle ergometer at 50%-60% of their max power output for 30 min followed by performing the Thorstensson test on an isokinetic dynamometer. A two-way (Supplement × Time) analysis of variance with repeated measures resulted in no significant interactions (p > .05) (PL: baseline day, acute day, chronic day vs. CM: baseline day, acute day, chronic day) for peak power (in watts) (469 ± 81, 490 ± 97, 502 ± 99 vs. 464 ± 85, 480 ± 103, 501 ± 81); peak torque (in newton meters) (150 ± 26, 157 ± 32, 161 ± 31 vs. 149 ± 27, 156 ± 33, 161 ± 26); fatigue rate (in percentage) (57 ± 9, 57 ± 10, 58 ± 9 vs. 57 ± 10, 56 ± 9, 58 ± 9); and heart rate (in beats per minute) (156 ± 17, 146 ± 13, 146 ± 9 vs. 155 ± 11, 146 ± 11, 146 ± 9). The results of this study suggest that neither acute nor chronic supplementation of CM had an effect on recovery or fatigue rate of the quadriceps.

A Primer on Repeated Sitting Exposure and the Cardiovascular System: Considerations for Study Design, Analysis, Interpretation, and Translation.

Sedentary behavior, particularly sitting, is ubiquitous in many contemporary societies. This is a major societal concern considering the evidence for a strong association between sitting behavior and cardiovascular disease morbidity and mortality. Unsurprisingly, leading public health agencies have begun to advocate "reduction" in sitting behavior. Though, the guidelines are typically vague and non-specific. The lack of specific guidelines for prolonged sitting is attributable to the absence of available evidence to facilitate guideline development. To inform policy, well-designed randomized controlled trials are required to test the efficacy of specific and translatable sitting reduction strategies. To guide the design of randomized controlled trials, this review postulates that several gaps in the literature first need to be filled. Following a general discussion of the importance of sitting behavior to contemporary societies, each of the following are discussed: (i) acute sitting exposure and systems physiology; (ii) recommendations for a systems physiology toolbox; (iii) study design considerations for acute sitting exposure; and (iv) translation of sitting-focused research.

A Call to Clarify the Intensity and Classification of Standing Behavior.

Public health guidelines for physical activity now include recommendations to break up prolonged sitting with light-intensity activities. Concurrently, interventions to increase standing have emerged, especially within the workplace in the form of sit-stand or standing workstations. Moreover, in short-duration studies, breaking up prolonged sitting with standing has been associated improved cardiometabolic outcomes. Publicly available estimates of the intensity of standing range from 1.5 to 2.3 metabolic equivalents (METs), neatly classifying standing as a light-intensity activity (>1.5 to <3.0 METs). Further delineation between 'active' and 'passive' standing has been proposed, with corresponding METs of >2.0 METs and ≤2.0 METs, respectively. However, this study reviews data suggesting that some standing (e.g., while performing deskwork) is substantially below the minimum light intensity activity threshold of 1.5 METs. These data bring into question whether standing should be universally classified as a light-intensity behavior. The objectives of this study are to (i) highlight discrepancies in classifying standing behavior in the human movement spectrum continuum, and (ii) to propose a realignment of the 'active' vs. 'passive' standing threshold to match the light intensity threshold to help provide a clearer research framework and subsequent public health messaging for the expected health benefits from standing.

Acceptability and Impact of Office-Based Resistance Exercise Breaks.

BACKGROUND: Breaking up sedentary behavior with standing or walking can decrease discomfort, fatigue, and sleepiness. However, less is known about acceptability and impact of resistance exercise breaks on these outcomes. Therefore, we evaluated the acceptability of resistance exercise breaks and their influence on discomfort, physical and mental fatigue, and sleepiness during occupational sitting. METHODS: Workers completed two 4-hour conditions in random order: prolonged sitting (SIT) and sitting with hourly resistance exercise breaks (REX). All outcomes were measured at baseline and every hour thereafter with five total breaks. Linear mixed models evaluated overall condition effects and differences at each hour. Cohen's d estimated magnitudes of effect. Acceptability was assessed via questionnaire after the REX condition and reported as percentages. FINDINGS: Fourteen adults (age: 53.4 ± 9.5 years, body mass index [BMI]: 30.9 ± 4.8 kg/m2) were enrolled. Although ratings of discomfort, fatigue, and sleepiness were typically lower during REX as compared with SIT, overall outcomes were not significantly different between conditions (p > .05). However, a significant reduction in mental fatigue at hour 4 in favor of the REX condition (ß = -0.48 log-points, p < .05, d = 0.37) was observed. Program acceptability questions revealed the majority (>50%) of participants reported a "4" or "5" on a 5-point Likert-type scale for all questions, indicating high acceptability for implementation. CONCLUSIONS/APPLICATION TO PRACTICE: Resistance exercise breaks had high acceptability and provided preliminary evidence of improving ratings of mental fatigue. More research is needed to better understand the role of resistance training to reduce sedentary behavior.

The Effects of a Simulated Workday of Prolonged Sitting on Seated versus Supine Blood Pressure and Pulse Wave Velocity in Adults with Overweight/Obesity and Elevated Blood Pressure.

We evaluated the effects of a simulated workday of prolonged sitting on blood pressure (BP) and pulse wave velocity (PWV) and examined whether posture (seated vs. supine) affected responses. Participants (n = 25) were adults, with overweight/obesity and elevated BP, and performed seated desk work for 7.5 h. BP and PWV were measured in seated and supine postures at baseline (7:15 a.m.), midday (12:05 p.m.), and afternoon (4:45 p.m.). Generalized linear mixed models evaluated the effects of prolonged sitting on BP and PWV within each posture and interactions by posture and sex. In the recommended postures, seated BP and supine carotid-femoral pulse wave velocity (cfPWV) and carotid-ankle pulse wave velocity (caPWV), but not carotid-radial pulse wave velocity (crPWV), significantly increased over the simulated seated workday (all p < 0.05; effect sizes [d] ranged from 0.25 to 0.44). Whilst no posture-by-time interactions were observed (p > 0.05), BP, caPWV, and crPWV were higher when seated versus supine (main effects of posture p < 0.05; d ranged from 0.30 to 1.04). Exploratory analysis revealed that females had greater seated BP responses (p for interaction <0.05); seated PWV and supine BP and PWV responses were similar by sex (p for interaction >0.05). A simulated workday of prolonged sitting increased seated BP and supine cfPWV and caPWV, and posture minimally influenced these responses. These results add to the evidence suggesting a deleterious effect of prolonged sitting on cardiovascular health.

The Effect of Vinegar Supplementation on High-Intensity Cycling Performance within Recreationally Trained Individuals.

Background and objectives: To investigate the effects of vinegar ingestion upon high-intensity cycle performance in recreationally trained individuals. Materials and methods: Twenty-two participants consumed one of the following in a randomized order on four separate visits: (1) 29 mL of vinegar along with 451 mL of water, (2) 39 g of sucrose along with 441 mL of water, (3) 29 mL of vinegar and 39 g of sucrose along with 412 mL of water, or (4) 480 mL of water alone. For each of the experimental testing sessions, all participants completed in order: (1) high-intensity cycle test 1, (2) fatiguing cycle test, (3) high-intensity cycle test 2, (4) supplement consumption, (5) 90 min rest period, and (6) high-intensity cycle test 3. Total time to exhaustion (TTE) and average heart rate (HR) for each set of sprints was used in analysis. Results: There was no supplement by time interaction or significant main treatment effect observed (p > 0.05) for either TTE or HR. However, there was a main time effect observed, with TTE (p = 0.0001) being lower for cycle test 2 than both cycle test 1 and cycle test 3, and cycle test 3 being lower than cycle test 1. HR (p = 0.0001) was lower for cycle test 3 than both cycle test 1 and cycle test 2, but HR for cycle test 1 did not differ significantly from HR for cycle test 2. Conclusions: The addition of vinegar or sucrose alone, or in combination, was ineffective in improving cycle sprinting TTE when performing three cycle tests.

Comparison of Acute Cardiometabolic Responses in a 7-Minute Body Weight Circuit to 7-Minute HIIT Training Protocol.

To investigate the acute cardiometabolic responses of a 7-minute bodyweight resistance exercise circuit (HICE) compared to a 7-minute high intensity interval training cycle protocol (HIIE). METHODS: Twelve apparently healthy and active young adults were enrolled in a randomized crossover study (HICE vs HIIE). The 12 HICE exercises used a 30:5 second exercise to rest ratio, followed by a 3-minute cool-down and was replicated in the HIIE cycle protocol. Following each protocol, subjects were seated for the next hour. Measurements included blood pressure (BP) heart rate, blood glucose and triglycerides, taken prior to exercise, immediately after, 15, 30, 45, and 60-minutes post-exercise. Blood glucose and triglycerides were only taken, immediately after and at 60-minutes. General mixed linear modeling was used to analyze the data and Cohen's d was calculated for effect size. Post hoc analysis of individual time points used Bonferroni adjustment. RESULTS: There was no significant difference in overall systolic BP between HIIE and HICE (p = 0.168). However, there was a significant difference in overall diastolic BP resulting a higher response in HIIE (p = 0.002). Immediately after exercise exhibited significant (p = 0.001) and trending, respectfully, higher values in diastolic BP for HIIE. The overall post-exercise heart rate was lower for HIIE vs HICE (p < 0.001). Blood glucose and Triglycerides had no overall difference between the two protocols (p = 0.104). CONCLUSION: The HICE protocol had a similar cardiometabolic response post-exercise to HIIE but did have a reduction in diastolic BP post-exercise. However, post-exercise heart rate was higher.

Effects of Alternating Standing and Sitting Compared to Prolonged Sitting on Cerebrovascular Hemodynamics.

PURPOSE: Previous research suggests that prolonged sitting may acutely reduce cerebral blood flow velocity (CBFv). The purpose of this study was to evaluate the effects of alternating standing and sitting vs prolonged sitting on CBFv. METHODS: This randomized crossover study enrolled working adults (N=25) with pre-to-stage 1 hypertension not using antihypertensive medications, and a body mass index from 25 to < 40 kg/m2. Subjects participated in two simulated workday conditions: 1) sitting continuously (SIT), and 2) alternating standing and sitting every 30 min (SS). Beat-to-beat systolic, mean and diastolic CBFv were recorded bilaterally for 1 min via insonation of the middle cerebral artery using transcranial Doppler ultrasonography before (morning), between (midday) and following (afternoon) two 3-hr 40 min work periods. RESULTS: Mean±SD age was 42±12 years, blood pressure (BP) was 132±9/83±8 mmHg, and BMI was 32±5 kg/m2. Cerebrovascular hemodynamics did not differ across condition (P>0.05). There were, however, significant nonlinear effects of time (decrease from morning to midday; increase from midday to afternoon) on systolic CBFv (P=0.014), mean CBFv (P=0.001), diastolic CBFv (P=0.002), and pulsatility index (P=0.038). When overall time effects were evaluated during each time interval, mean and diastolic CBFv significantly decreased morning to midday and all CBFv increased from midday to afternoon. When separated by condition, significant time effects were observed for all CBFv during SIT (P<0.02) but not SS (P>0.05). CONCLUSIONS: In individuals with elevated BP and BMI, CBFv significantly decreased by midday and increased by afternoon, especially during a workday of prolonged sitting. Future studies should evaluate the combination of frequent walks and a sit-stand desk to break up prolonged sitting.

Acute cardiometabolic effects of interrupting sitting with resistance exercise breaks.

Interrupting prolonged sitting with light activity breaks, such as short walks, improves cardiometabolic outcomes, yet less is known about the impact of resistance exercise breaks. This study examined the effects of hourly, guidelines-based simple resistance exercise breaks on acute cardiometabolic health outcomes over a simulated work period. Fourteen adults (age: 53.4 ± 9.5 years, body mass index: 30.9 ± 4.8 kg/m2) completed 2 randomized 4-h conditions: prolonged sitting (SIT) and hourly resistance exercise breaks (REX). Glucose, triglycerides, blood pressure, and heart rate were measured at baseline and then hourly. Pulse wave velocity (PWV) was measured before and after each condition. Linear mixed models evaluated overall condition effects and differences at each hour. Cohen's d estimated magnitude of effects. Four-hour glucose area under the curve (AUC) did not differ by condition (REX vs. SIT: ß = -0.35 mmol/L, p = 0.278, d = 0.51). However, an attenuation of postprandial glucose at 1 h (ß = -0.69 mg/dL, p = 0.004, d = 1.02) in REX compared with SIT was observed. Triglyceride AUC, mean blood pressure, and PWV did not differ significantly between REX and SIT overall or any time point (all p > 0.05). Heart rate was higher across the experimental period in REX versus SIT (ß = 3.3 bpm, p < 0.001, d = 0.35) and individual time points (ß ≥ 3.2 bpm, p ≤ 0.044, d ≥ 0.34). Resistance exercise breaks can potentially improve 1-h postprandial glucose, but may not acutely benefit other cardiometabolic outcomes. Future studies employing guidelines-based resistance exercises to interrupt prolonged sitting with a larger sample and longer follow-up are warranted.

Accuracy and Acceptability of Commercial-Grade Physical Activity Monitors in Older Adults.

The aim of this study was to evaluate accuracy of seven commercial activity monitors in measuring steps in older adults with varying walking abilities and to assess monitor acceptability and usability. Forty-three participants (age = 87 ± 5.7 years) completed a gait speed assessment, two walking trials while wearing the activity monitors, and questionnaires about usability features and activity monitor preferences. The Accusplit AX2710 Accelerometer Pedometer had the highest accuracy (93.68% ± 13.95%), whereas the Fitbit Charge had the lowest (39.12% ± 40.3%). Device accuracy varied based on assistive device use, and none of the monitors were accurate at gait speeds <0.08 m/s. Barriers to monitor usability included inability to apply monitor and access the step display. Monitor accuracy was rated as the most important feature, and ability to interface with a smart device was the least important feature. This study identified the limitations of the current commercial activity monitors in both step counting accuracy and usability features for older adults.

Effect of Using a Sit-Stand Desk on Ratings of Discomfort, Fatigue, and Sleepiness Across a Simulated Workday in Overweight and Obese Adults.

BACKGROUND: Limited research examines the influence of sit-stand desks on ratings of discomfort, sleepiness, and fatigue. This study evaluated the time course of these outcomes over 1 day. METHODS: Adults (N = 25) completed a randomized cross-over study in a laboratory with two 8-hour workday conditions: (1) prolonged sitting (SIT) and (2) alternating sitting and standing every 30 minutes (SIT-STAND). Sleepiness was assessed hourly. Discomfort, physical fatigue, and mental fatigue were measured every other hour. Linear mixed models evaluated whether these measures differed across conditions and the workday. Effect sizes were calculated using Cohen's d. RESULTS: Participants were primarily white (84%) males (64%), with mean (SD) body mass index of 31.9 (5.0) kg/m2 and age 42 (12) years. SIT-STAND resulted in decreased odds of discomfort (OR = 0.37, P = .01) and lower overall discomfort (ß = -0.19, P < .001, d = 0.42) versus SIT. Discomfort during SIT-STAND was lower in the lower and upper back, but higher in the legs (all Ps< .01, d = 0.26-0.42). Sleepiness (ß = -0.09, P = .01, d = 0.15) and physical fatigue (ß = -0.34, P = .002, d = 0.34) were significantly lower in SIT-STAND. Mental fatigue was similar across conditions. CONCLUSIONS: Sit-stand desks may reduce acute levels of sleepiness, physical fatigue, and both overall and back discomfort. However, levels of lower extremity discomfort may be increased with acute exposure.

Accuracy of Objective Physical Activity Monitors in Measuring Steps in Older Adults.

Objective: The aim of this study is to evaluate accuracy of research activity monitors in measuring steps in older adults with a range of walking abilities. Method: Participants completed an initial assessment of gait speed. The accuracy of each monitor to record 100 steps was assessed across two walking trials. Results: In all, 43 older adults (age 87 ± 5.7 years, 81.4% female) participated. Overall, the StepWatch had the highest accuracy (99.0% ± 1.5%), followed by the ActivPAL (93.7% ± 11.1%) and the Actigraph (51.4% ± 35.7%). The accuracy of the Actigraph and ActivPAL varied according to assistive device use, and the accuracy of all three monitors differed by gait speed category (all p < .05). StepWatch was highly accurate (⩾97.7) across all conditions. Discussion: The StepWatch and ActivPAL monitor were reasonably accurate in measuring steps in older adults who walk slowly and use an assistive device. The Actigraph significantly undercounted steps in those who walk slow or use an assistive device. Researchers should consider gait speed and the use of assistive devices when selecting an activity monitor.

Reducing sedentary behaviour to decrease chronic low back pain: the stand back randomised trial.

OBJECTIVE: The Stand Back study evaluated the feasibility and effects of a multicomponent intervention targeting reduced prolonged sitting and pain self-management in desk workers with chronic low back pain (LBP). METHODS: This randomised controlled trial recruited 27 individuals with chronic LBP, Oswestry Disability Index (ODI) >10% and desk jobs (sitting ≥20 hours/week). Participants were randomised within strata of ODI (>10%-<20%, ≥20%) to receive bimonthly behavioural counselling (in-person and telephone), a sit-stand desk attachment, a wrist-worn activity-prompting device and cognitive behavioural therapy for LBP self-management or control. Self-reported work sitting time, visual analogue scales (VAS) for LBP and the ODI were assessed by monthly, online questionnaires and compared across intervention groups using linear mixed models. RESULTS: Baseline mean (SD) age was 52 (11) years, 78% were women, and ODI was 24.1 (10.5)%. Across the 6-month follow-up in models adjusted for baseline value, work sitting time was 1.5 hour/day (P<0.001) lower comparing intervention to controls. Also across follow-up, ODI was on average 8 points lower in intervention versus control (P=0.001). At 6 months, the relative decrease in ODI from baseline was 50% in intervention and 14% in control (P=0.042). LBP from VAS was not significantly reduced in intervention versus control, though small-to-moderate effect sizes favouring the intervention were observed (Cohen's d ranged from 0.22 to 0.42). CONCLUSION: An intervention coupling behavioural counselling targeting reduced sedentary behaviour and pain self-management is a translatable treatment strategy that shows promise for treating chronic LBP in desk-bound employees. TRIAL REGISTRATION NUMBER: NCT0224687; Pre-results.