The effects of prolonged sitting, prolonged standing, and activity breaks on vascular function, and postprandial glucose and insulin responses: A randomised crossover trial.

The objective of this study was to compare acute effects of prolonged sitting, prolonged standing and sitting interrupted with regular activity breaks on vascular function and postprandial glucose metabolism. In a randomized cross-over trial, 18 adults completed: 1. Prolonged Sitting; 2. Prolonged Standing and 3. Sitting with 2-min walking (5 km/h, 10% incline) every 30 min (Regular Activity Breaks). Flow mediated dilation (FMD) was measured in the popliteal artery at baseline and 6 h. Popliteal artery hemodynamics, and postprandial plasma glucose and insulin were measured over 6 h. Neither raw nor allometrically-scaled FMD showed an intervention effect (p = 0.285 and 0.159 respectively). Compared to Prolonged Sitting, Regular Activity Breaks increased blood flow (overall effect of intervention p<0.001; difference = 80%; 95% CI 34 to 125%; p = 0.001) and net shear rate (overall effect of intervention p<0.001; difference = 72%; 95% CI 30 to 114%; p = 0.001) at 60 min. These differences were then maintained for the entire 6 h. Prolonged Standing increased blood flow at 60 min only (overall effect of intervention p<0.001; difference = 62%; 95% CI 28 to 97%; p = 0.001). Regular Activity Breaks decreased insulin incremental area under the curve (iAUC) when compared to both Prolonged Sitting (overall effect of intervention P = 0.001; difference = 28%; 95% CI 14 to 38%; p<0.01) and Prolonged Standing (difference = 19%; 95% CI 4 to 32%, p = 0.015). There was no intervention effect on glucose iAUC or total AUC (p = 0.254 and 0.450, respectively). In normal-weight participants, Regular Activity Breaks induce increases in blood flow, shear stress and improvements in postprandial metabolism that are associated with beneficial adaptations. Physical activity and sedentary behaviour messages should perhaps focus more on the importance of frequent movement rather than simply replacing sitting with standing.

Factors Influencing Energy Drink Consumption in Participants and Viewers of Extreme Sports.

OBJECTIVE: To quantify energy drink consumption and influences affecting consumption in those who participate in or watch extreme sports. METHODS: An online survey, informed by focus groups, was administered via Quadrics®. Advertisement was via social media, emailing extreme sport clubs, flyers at extreme sport locations, and word of mouth. Participation was limited to those >18 y who watched and/or participated in extreme sports. The study was conducted in New Zealand, with international online availability. Variables measured comprised age, sex, energy drink consumption, reasons for their use, extreme sport viewing, advertising, and sponsorship. Logistic regression models were utilised. RESULTS: Amongst participants who completed the questionnaire (n = 247), the mean (SD) age was 26.2 (8.2) y, 40.5% were female, 57.9% consumed energy drinks, and 25.5% consumed >one per week. For every year older, odds of consuming energy drinks were 3.1% lower (p=0.04). A 31% increase in energy drink consumption for every single increase of viewing extreme sport per week was observed (p=0.009); however, reported viewing of advertising was not associated with increased consumption. CONCLUSIONS: A large proportion of extreme sport enthusiasts regularly consume energy drinks, especially younger adults. Extreme sport viewing, where energy drink sponsorship is common, appears to increase their consumption, even if not considered advertising by the viewers themselves.

Energy utilisation and postprandial responses during sitting interrupted by regular activity breaks.

Interrupting sedentary behaviour with regular activity breaks benefits glycaemic control; however, the influence of the energy utilised during these activity breaks on postprandial metabolic response is relatively unknown. Therefore, the aim of this study was to investigate whether the energy utilisation of regular (every 30 min) short (1 min 40 s or 2 min) activity breaks was associated with the lowering of postprandial glycaemia, insulinemia and lipidemia.Using separate data from two previously performed studies (ALPhA Study n = 65, age 25.7 (5.2) y, 40% male, BMI 23.6 (4.1) kg · m-2. ABPA study n = 35, age 25.1 (3.7) y, 31% male, BMI 23.4 (3.2) kg · m-2) we investigated the association between energy utilisation (measured by indirect calorimetry) and postprandial glucose, insulin and triglycerides during prolonged sitting, and regular activity breaks.Results.Mixed effects regression models indicated that energy utilisation was not consistently associated with postprandial glucose, insulin or triglyceride responses (p > 0.05 for all). Additionally, there was some indication that energy utilisation was obscuring (mildly suppressing) the effects of regular activity breaks on glucose, insulin and triglyceride iAUC.Conclusions.If energy utilisation does not mediate the association between regular activity breaks and postprandial glycaemic response, it is possible that it is the frequency of the activity breaks that is beneficial.

Association between the faecal short-chain fatty acid propionate and infant sleep.

The gut microbiota harvests energy from indigestible plant polysaccharides, forming short-chain fatty acids (SCFAs) that are absorbed from the bowel. SCFAs provide energy-presumably after easily digested food components have been absorbed from the small intestine. Infant night waking is believed by many parents to be due to hunger. Our objective was to determine whether faecal SCFAs are associated with longer uninterrupted sleep in infants. Infants (n = 57) provided faecal samples for determining SCFAs (7 months of age), and questionnaire data for determining infant sleep (7 and 8 months). Linear regression determined associations between SCFAs-faecal acetate, propionate and butyrate-and sleep. For each 1% higher propionate at 7 months of age, the longest night sleep was 6 (95% CI: 1, 10) minutes longer at both 7 and 8 months. A higher proportion of total faecal SCFA as propionate was associated with longer uninterrupted infant sleep.

No clear benefit of muscle heating on hypertrophy and strength with resistance training.

Heat is a major stressor during exercise, though its value in driving adaptation is not well understood. Muscle heating can upregulate pathways facilitating protein synthesis and could thereby enhance effects of exercise training, however, few studies have investigated this possibility. We examined whether heating active muscle during resistance training differentially affected physical and functional adaptations. Within a randomised contralateral-limb control study, ten healthy, resistance-untrained individuals (21 ± 3 y; 5 female) completed 30 sessions of progressive resistance training (12 weeks), performing 4 × 8 unilateral knee extensions at 70% of 1RM. One randomly-allocated thigh was heated during, and for 20 min after, each session using an electric pad eliciting muscle temperatures of >38 °C (HOT); the contralateral limb remained unheated (CON). Training intensity was progressed using 4-weekly strength assessments. Quadricep lean mass (measured using DXA) increased by 15 ± 7% in HOT (p = 0.00) and 15 ± 6% in CON (p = 0.00); the difference being trivial (p = 0.94). Peak isokinetic torque at 90°.s-1 increased by 30 ± 25% (HOT; p = 0.00) and 34 ± 33% (CON; p = 0.01), with no difference (p = 0.84) between limbs. Rate of torque development increased ∼40%, with no difference between limbs (p = 0.73). The increase in 3-RM strength was also similar in HOT (75 ± 16%) and CON (71 ± 14%; p = 0.80 for difference). No differences in mass or strength changes were evident between sexes. In conclusion, supplemental heating of active muscle during and after each bout of resistance training showed no clear positive (or negative) effect on training-induced hypertrophy or function.

Physical and Physiological Demands of Elite Rugby Union Officials.

PURPOSE: To examine the movement and physiological demands of rugby union officiating in elite competition. METHODS: Movement demands of 9 elite officials across 12 Super Rugby matches were calculated, using global positioning system devices. Total distance (in m), relative distance (in m·min-1), and percentage time spent in various speed zones were calculated across a match. Heart-rate (HR) responses were also recorded throughout each match. Cohen d effect sizes were reported to examine the within-match variations. RESULTS: The total distance covered was 8030 (506) m, with a relative distance of 83 (5) m·min-1 and with no differences observed between halves. Most game time was spent at lower movement speeds (76% [2%]; <2.0 m·s-1), with large effects for time spent >7.0 m·s-1 between halves (d = 2.85). Mean HR was 154 (10) beats·min-1 (83.8 [2.9]%HRmax), with no differences observed between the first and second halves. Most game time was spent between 81%HRmax and 90%HRmax (40.5% [7.5%]) with no observable differences between halves. Distances covered above 5.1 m·s-1 were highest during the first 10 min of a match, while distance at speeds 3.7 to 5 m·s-1 decreased during the final 10 min of play. CONCLUSIONS: These findings highlight the highly demanding and intermittent nature of rugby union officiating, with only some minor variations in physical and physiological demands across a match. These results have implications for the physical preparation of professional rugby union referees.

Interrupting Prolonged Sitting with Regular Activity Breaks does not Acutely Influence Appetite: A Randomised Controlled Trial.

Regular activity breaks increase energy expenditure; however, this may promote compensatory eating behaviour. The present study compared the effects of regular activity breaks and prolonged sitting on appetite. In a randomised, cross-over trial, 36 healthy adults (BMI (Body Mass Index) 23.9 kg/m² (S.D. = 3.9)) completed four, two-day interventions: two with prolonged sitting (SIT), and two with sitting and 2 min of walking every 30 min (RAB). Standardized meals were provided throughout the intervention, with an ad libitum meal at the end of Day 2. Appetite and satiety were assessed throughout both days of each intervention using five visual analogue scales. The five responses were combined into a single appetite response at each time point. The area under the appetite response curve (AUC) was calculated for each day. Intervention effects for appetite response AUC and ad libitum meal intake were tested using linear mixed models. Appetite AUC did not differ between interventions (standardised effect of RAB compared to SIT: Day 1: 0.11; 95% CI: -0.28, 0.06; p = 0.212; Day 2: 0.04; 95% CI: -0.15, 0.24; p = 0.648). There was no significant difference in energy consumed at the ad libitum lunch meal on Day 2 between RAB and SIT. Interrupting prolonged sitting with regular activity breaks does not acutely influence appetite or volume of food consumed, despite inferred increases in energy expenditure. Longer-term investigation into the effects of regular activity breaks on energy balance is warranted.

Sedentary Behavior and Body Weight and Composition in Adults: A Systematic Review and Meta-analysis of Prospective Studies.

BACKGROUND: The cumulative effect of too much sedentary behavior may contribute to weight gain and obesity. OBJECTIVE: The aim of this study was to conduct a systematic review and meta-analysis of prospective cohorts and randomized controlled studies to determine the association between sedentary behavior and body weight and obesity in adults. DATA SOURCES AND STUDY SELECTION: Relevant studies were identified from searches of the MEDLINE, Embase, AMED and PubMed databases up to May 2017, and by manual searches of in-text citations. Studies that evaluated the association in adults between sedentary behavior and body weight or obesity, while controlling for physical activity, were included. Overall, 31 publications met the eligibility criteria, including 23 prospective cohort studies with data that could be extracted for a quantitative meta-analysis, and a single randomized controlled trial. RESULTS: There were no significant associations between sedentary behavior and any measure of body weight or obesity, with the exception of waist circumference. For the latter outcome, over a 5-year follow-up period, each 1 h per day increase-from baseline to follow-up-in sedentary behavior was associated with a 0.02 mm [95% confidence interval (CI) 0.01-0.04; p = 0.001) increase in waist circumference. The odds ratio of becoming overweight or obese was 1.33 (95% CI 1.11-1.60; p = 0.001) in the highest compared with lowest categories of sedentary behavior. CONCLUSIONS: Meta-analysis of data from prospective cohort studies showed small, inconsistent and non-significant associations between sedentary behavior and body weight.

Can Neck Strength be Measured Using a Single Maximal Contraction in a Simulated Contact Position?

Salmon, DM, Handcock, PJ, Sullivan, SJ, Rehrer, NJ, and Niven, BE. Can neck strength be measured using a single maximal contraction in a simulated contact position? J Strength Cond Res 32(8): 2166-2173, 2018-Neck strengthening has been postulated to potentially reduce the incidence and severity of concussions and neck injuries in collision-based sports. A quick and reliable method to assess neck strength would permit identification of those at risk and tracking of progress after injury. The purpose of this study was to determine if neck strength could be reliably assessed in a simulated contact posture using a single maximal contraction. During a single session, 30 healthy male university students performed 3 maximal voluntary contractions of the neck musculature in each of the following directions: extension (Ext), flexion (Flx), left lateral flexion (LtFlx), and right lateral flexion (RtFlx). To evaluate the reliability of these measures, intraclass correlation coefficients (ICCs) were calculated. The findings revealed a significant effect for direction (p < 0.01), where Ext (234.8 N) tested stronger than Flx (141.0 N), LtFlx (134.5 N), and RtFlx (123.0 N). In addition, Flx tested stronger than RtFlx (p = 0.03). No other differences were observed between LtFlx and RtFlx. When the combined mean values of the trials (1: 151.6 N, 2: 160.0 N, 3: 163.5 N) and the interaction contrast were compared, these were not significant (p = 0.08-1.0), indicating no changes in peak force occurred over the 3 trials. The ICC values for Ext, RtFlx, and LtFlx were all "excellent" (0.91-0.94), whereas Flx demonstrated "good" reliability (0.86). In a simulated contact posture, a reliable measure of peak force was obtained using a single maximal contraction. This may have practical applications for the quick and reliable assessment of contact sport athletes in a position that has functional relevance to their sports.

Neck strength and self-reported neck dysfunction: what is the impact of a season of Rugby Union?

BACKGROUND: Neck strength has been reported to reduce the incidence of concussions and neck injuries. However, little is known about how neck strength changes over a playing season. The aim of this study was to understand the impact a 20-week rugby season has on neck strength, neck pain (NP) and neck stiffness (NS) in a cohort of rugby players, relative to a non-contact control group. METHODS: This prospective cohort study employed a fixed-frame dynamometer to measure neck strength in a simulated contact posture in rugby players (N.=32) and controls (N.=15). During each assessment, participants performed a single maximal voluntary contraction in extension, flexion, left (LtFlx) and right lateral flexion (RtFlx). To quantify neck dysfunction, "current," "average," and "worst" NP and NS were measured using visual analogue scales. RESULTS: Post-season improvements (35.3-59.1 N) in neck strength were observed for the forwards for all measured directions (P<0.01), and were significant when compared to controls. For the backs, improvements were seen in extension, flexion and LtFlx (P=0.01-0.05), with only extension (29.8 N) and flexion (35.14 N) remaining significant when contrasted against the controls. The controls' neck strength remained unchanged over the season. Despite improvements in peak force, NP increased (all three measures) for the forwards (P=0.01-0.04), while only current (P=0.03) and worst NP (P=0.04) increased for the backs. Unexpectedly, NS remained unchanged for the forwards, while backs reported increases for all three measures (P=0.01-0.02). CONCLUSIONS: A season of rugby resulted in neck strength adaptations in the rugby players. Despite these improvements, increased levels of NP and NS were reported.

Regular activity breaks combined with physical activity improve postprandial plasma triglyceride, nonesterified fatty acid, and insulin responses in healthy, normal weight adults: A randomized crossover trial.

BACKGROUND: Compared with prolonged sitting, regular activity breaks immediately lower postprandial glucose and insulin, but not triglyceride responses. Postprandial triglycerides can be lowered by physical activity but the effect is often delayed by ∼12 to 24 hours. OBJECTIVE: The objective of the study was to determine whether regular activity breaks affect postprandial triglyceride response in a delayed manner similar to physical activity. METHODS: In a randomized crossover trial, 36 adults (body mass index 23.9 kg/m2 [standard deviation 3.9]) completed four 2-day interventions: (1) prolonged sitting (SIT); (2) prolonged sitting with 30 minutes of continuous walking (60% VO2max), at the end of Day 1 (SIT + PAD1); (3) Sitting with 2 minutes of walking (60% VO2max) every 30 minutes (RAB); (4) A combination of the continuous walking and regular activity breaks in 2 and 3 above (RAB + PAD1). Postprandial plasma triglyceride, nonesterified fatty acids, glucose, and insulin responses were measured in venous blood over 5 hours on Day 2. RESULTS: Compared with SIT, both RAB (difference: -43.61 mg/dL·5 hours; 95% confidence interval [CI] -83.66 to -2.67; P = .035) and RAB + PAD1 (-65.86 mg/dL·5 hours; 95% CI -112.14 to -19.58; P = .005) attenuated triglyceride total area under the curve (tAUC). RAB + PAD1 produced the greatest reductions in insulin tAUC (-23%; 95% CI -12% to -31%; P < .001), whereas RAB resulted in the largest increase in nonesterified fatty acids (tAUC, 10.08 mg/dL·5 hours; 95% CI 5.60-14.84; P < .001). There was no effect on glucose tAUC (P = .290). CONCLUSIONS: Postprandial triglyceride response is attenuated by regular activity breaks, when measured ∼24 hours after breaks begin. Combining regular activity breaks with 30 minutes of continuous walking further improves insulinemic and lipidemic responses.

Similar metabolic response to lower- versus upper-body interval exercise or endurance exercise.

PURPOSE: To compare energy use and substrate partitioning arising from repeated lower- versus upper-body sprints, or endurance exercise, across a 24-h period. METHODS: Twelve untrained males (24±4 y) completed three trials in randomized order: (1) repeated sprints (five 30-s Wingate, 4.5-min recovery) on a cycle ergometer (SITLegs); (2) 50-min continuous cycling at 65% V̇O2max (END); (3) repeated sprints on an arm-crank ergometer (SITArms). Respiratory gas exchange was assessed before and during exercise, and at eight points across 22h of recovery. RESULTS: Metabolic rate was elevated to greater extent in the first 8h after SITLegs than SITArms (by 0.8±1.1kJ/min, p=0.03), and tended to be greater than END (by 0.7±1.3kJ/min, p=0.08). Total 24-h energy use (exercise+recovery) was equivalent between SITLegs and END (p = 0.55), and SITLegs and SITArms (p=0.13), but 24-h fat use was higher with SITLegs than END (by 26±38g, p=0.04) and SITArms (by 27±43g, p=0.05), whereas carbohydrate use was higher with SITArms than SITLegs (by 32±51g, p=0.05). Plasma volume-corrected post-exercise and fasting glucose and lipid concentrations were unchanged. CONCLUSION: Despite much lower energy use during five sprints than 50-min continuous exercise, 24-h energy use was not reliably different. However, (i) fat metabolism was greater after sprints, and (ii) carbohydrate metabolism was greater in the hours after sprints with arms than legs, while 24-h energy usage was comparable. Thus, sprints using arms or legs may be an important adjunct exercise mode for metabolic health.

The Beneficial Effect of Parasympathetic Reactivation on Sympathetic Drive During Simulated Rugby Sevens.

PURPOSE: To determine whether a facilitated recovery via cold-water immersion (CWI) after simulated rugby sevens would influence parasympathetic reactivation and repeated-sprint (RS) performance across 6 matches in a 2-d tournament. METHODS: Ten male team-sport athletes completed 6 rugby sevens match simulations over 2 d with either postmatch passive recovery (PAS) or CWI in a randomized crossover design. Parasympathetic reactivation was determined via the natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent R-R intervals (ln rMSSD). RS performance was calculated as time taken (s) to complete 6 × 30-m sprints within the first half of each match. RESULTS: There were large increases in postintervention ln rMSSD between CWI and PAS after all matches (ES 90% CL: +1.13; ±0.21). Average heart rate (HR) during the RS performance task (HRAverage RS) was impaired from baseline from match 3 onward for both conditions. However, HRAverage RS was higher with CWI than with PAS (ES 90% CL: 0.58; ±0.58). Peak HR during the RS performance task (HRPeak RS) was similarly impaired from baseline for match 3 onward during PAS and for match 4 onward with CWI. HRPeak RS was very likely higher with CWI than with PAS (ES 90% CL: +0.80; ±0.56). No effects of match or condition were observed for RS performance, although there were moderate correlations between the changes in HRAverage RS (r 90% CL: -0.33; ±0.14), HRPeak RS (r 90% CL: -0.38; ±0.13), and RS performance. CONCLUSION: CWI facilitated cardiac parasympathetic reactivation after a simulated rugby sevens match. The decline in average and peak HR across matches was partially attenuated by CWI. This decline was moderately correlated with a reduction in RS performance.

Reliability of repeated isometric neck strength and endurance testing in a simulated contact posture.

The purpose of this study was to examine the reliability of repeated isometric measurements of neck strength and endurance in a simulated rugby contact posture. Data were collected from healthy active university students (n = 20) over 3 sessions. Each session consisted of a single maximal voluntary contraction (MVC) and endurance trial for extension and flexion. The endurance trials were analyzed to determine the area under the force curve (%AUC) and the time to fatigue (TTF). Reliability was calculated using the SEM and minimal detectable change (MDC). The results revealed that the MVC values for extension were nonsignificant for session (p = 0.21), whereas some session differences were seen for flexion (p = 0.01), where session 1, 115.3 N was less than session 3, 126.4 N (p = 0.03). For %AUC, flexion values (%AUC 86.0) were greater than extension (%AUC 59.4) (p = 0.02). A similar effect was observed for TTF with flexion (125.0 seconds) having significantly greater TTF than extension (86.1 seconds). For peak force, the greatest SEM and MDC were achieved for extension (15.3 and 42.3 N), while flexion produced lower values (11.3 and 31.2 N). In contrast, for the endurance trials, SEM and MDC were greater in flexion than in extension. The findings from this study indicate that the neck musculature can be reliably assessed in a simulated contact posture. For peak force, extension provided more consistent measures across time as there seems to be a learning effect for flexion. Additionally, the SEM and MDC scores provide a useful tool for future assessment of neck strength and endurance.

Protein supplements: do they alter dietary intakes?

Effects of protein versus mixed macronutrient supplementation on total energy intake (TEI) and protein intake during an ad libitum diet were examined. Trained males undertook two, 2-week dietary interventions which were randomized, double blinded, and separated by 2 weeks. These were high-protein supplementation (HP: 1034.5 kJ energy, 29.6 g protein, 8.7 g fat and 12.3 g CHO) and standard meal supplementation (SM: 1039 kJ energy, 9.9 g protein, 9.5 g fat, and 29.4 g CHO) consumed daily following a week of baseline measures. Eighteen participants finished both interventions and one only completed HP. TEI (mean ± SD) was not different between baseline (11148 ± 3347 kJ) and HP (10705 ± 3143 kJ) nor between baseline and SM (12381 ± 3877 kJ), however, TEI was greater with SM than HP (923 ± 4015 kJ p = .043). Protein intake (%TEI) was greater with HP (22.4 ± 6.2%) than baseline (19.4 ± 5.4%; p = .008) but not SM (20.0 ± 5.0%). No differences in absolute daily protein intake were found. Absolute CHO intake was greater with SM than HP (52.0 ± 89.5 g, p = .006). No differences in fat intake were found. Body mass did not change between baseline (82.7 ± 11.2 kg) and either HP (83.1 ± 11.7 kg) or SM (82.9 ± 11.0 kg). Protein supplementation increases the relative proportion of protein in the diet, but doesn't increase the absolute amount of total protein or energy consumed. Thus some compensation by a reduction in other foods occurs. This is in contrast to a mixed nutrient supplement, which does not alter the proportion of protein consumed but does increase TEI.

Body armour: the effect of load, exercise and distraction on landing forces.

We investigated the effect of added load and intense exercise on jump and landing performance and ground reaction force (GRF) during landings where attentional demand was varied. Fifty-two males (37 ± 9.2 years, 180.7 ± 6.1 cm, 90.2 ± 11.6 kg, maximal aerobic fitness (VO(2max)) 50 ± 8.5 ml (.) kg(-1 .) min(-1), BMI 27.6 ± 3.1, mean ± s) completed a VO(2max) test. Experimental sessions were completed (≥4 days in between) in a randomised counterbalanced order, one while wearing body armour and appointments (loaded) and one without load (unloaded). A vertical jump, a drop landing concentrating on safe touchdown, a drop jump and a drop landing with an attentional distraction were performed. These were repeated 1 min after a 5-min treadmill run. Mean jump height decreased by 12% (P < 0.001) with loading and a further by 6% following the running task. Peak GRFs were increased by 13-19% with loading (P < 0.001) depending on the landing task demands and a further by 4-9% following intense exercise. The distracted drop landing had significantly higher GRFs compared to all other landings. Results demonstrate that added load impacts on jumping and landing performance, an effect that is amplified by prior intense exercise, and distraction during landing. Such increases in GRF apply to police officer performance in their duties and may increase the risk of injury.

Breaking prolonged sitting reduces postprandial glycemia in healthy, normal-weight adults: a randomized crossover trial.

BACKGROUND: Sedentary behavior is a risk factor for cardiometabolic disease. Regularly interrupting sedentary behavior with activity breaks may lower this risk. OBJECTIVE: We compared the effects of prolonged sitting, continuous physical activity combined with prolonged sitting, and regular activity breaks on postprandial metabolism. DESIGN: Seventy adults participated in a randomized crossover study. The prolonged sitting intervention involved sitting for 9 h, the physical activity intervention involved walking for 30 min and then sitting, and the regular-activity-break intervention involved walking for 1 min 40 s every 30 min. Participants consumed a meal-replacement beverage at 60, 240, and 420 min. RESULTS: The plasma incremental area under the curve (iAUC) for insulin differed between interventions (overall P < 0.001). Regular activity breaks lowered values by 866.7 IU · L(-1) · 9 h(-1) (95% CI: 506.0, 1227.5 IU · L(-1) · 9 h(-1); P < 0.001) when compared with prolonged sitting and by 542.0 IU · L(-1) · 9 h(-1) (95% CI: 179.9, 904.2 IU · L(-1) · 9 h(-1); P = 0.003) when compared with physical activity. Plasma glucose iAUC also differed between interventions (overall P < 0.001). Regular activity breaks lowered values by 18.9 mmol · L(-1) · 9 h(-1) (95% CI: 10.0, 28.0 mmol · L(-1) · 9 h(-1); P < 0.001) when compared with prolonged sitting and by 17.4 mmol · L(-1) · 9 h(-1) (95% CI: 8.4, 26.3 mmol · L(-1) · 9 h(-1); P < 0.001) when compared with physical activity. Plasma triglyceride iAUC differed between interventions (overall P = 0.023). Physical activity lowered values by 6.3 mmol · L(-1) · 9 h(-1) (95% CI: 1.8, 10.7 mmol · L(-1) · 9 h(-1); P = 0.006) when compared with regular activity breaks. CONCLUSION: Regular activity breaks were more effective than continuous physical activity at decreasing postprandial glycemia and insulinemia in healthy, normal-weight adults. This trial was registered with the Australian New Zealand Clinical Trials registry as ACTRN12610000953033.