Reward for fat and sweet dimensions of food are altered by an acute bout of running in healthy young men.

Acute moderate- to high-intensity exercise, primarily aerobic exercise, has been reported to decrease food reward in brain regions via the hedonic pathways and reduce preference for high-energy or high-fat foods. However, studies examining food reward responses to acute exercise have been limited to measuring food reward only after exercise and less frequently before and after exercise. Therefore, the changes in food reward in response to acute exercise remain unclear. This study investigated the effect of acute running on food reward in healthy young men. Fourteen young healthy men (mean ± standard deviation, age; 23 ± 2 years, body mass index; 21 ± 2 kg/m2) completed two trials (i.e., exercise and control) in a randomised, crossover design. Participants performed a 30-min running bout at 70% of maximal oxygen uptake or sitting rest before and after food reward evaluation with a computer-based food choice behaviour task tool. Food reward was assessed for foods varying in fat content and sweet taste, and there were four assessment parameters: explicit liking, explicit wanting, implicit wanting and frequency of choice of each food category (relative preference). Explicit and implicit wanting, and relative preference for high-fat relative to low-fat foods were reduced after the exercise trial compared to the control trial (trial-by-time interaction, all p ≤ 0.02). Implicit wanting and relative preference for sweet relative to savoury foods were increased after the exercise trial compared to the control trial (trial-by-time interaction, all p ≤ 0.003). These findings indicate that moderate-intensity acute running alters the reward bias away from high fat towards low fat foods and away from savoury towards sweet foods in healthy young men.

Exploring the acute effects of running on cerebral blood flow and food cue reactivity in healthy young men using functional magnetic resonance imaging.

Acute exercise suppresses appetite and alters food-cue reactivity, but the extent exercise-induced changes in cerebral blood flow (CBF) influences the blood-oxygen-level-dependent (BOLD) signal during appetite-related paradigms is not known. This study examined the impact of acute running on visual food-cue reactivity and explored whether such responses are influenced by CBF variability. In a randomised crossover design, 23 men (mean ± SD: 24 ± 4 years, 22.9 ± 2.1 kg/m2 ) completed fMRI scans before and after 60 min of running (68% ± 3% peak oxygen uptake) or rest (control). Five-minute pseudo-continuous arterial spin labelling fMRI scans were conducted for CBF assessment before and at four consecutive repeat acquisitions after exercise/rest. BOLD-fMRI was acquired during a food-cue reactivity task before and 28 min after exercise/rest. Food-cue reactivity analysis was performed with and without CBF adjustment. Subjective appetite ratings were assessed before, during and after exercise/rest. Exercise CBF was higher in grey matter, the posterior insula and in the region of the amygdala/hippocampus, and lower in the medial orbitofrontal cortex and dorsal striatum than control (main effect trial p ≤ .018). No time-by-trial interactions for CBF were identified (p ≥ .087). Exercise induced moderate-to-large reductions in subjective appetite ratings (Cohen's d = 0.53-0.84; p ≤ .024) and increased food-cue reactivity in the paracingulate gyrus, hippocampus, precuneous cortex, frontal pole and posterior cingulate gyrus. Accounting for CBF variability did not markedly alter detection of exercise-induced BOLD signal changes. Acute running evoked overall changes in CBF that were not time dependent and increased food-cue reactivity in regions implicated in attention, anticipation of reward, and episodic memory independent of CBF.

The effects of different temperatures of post-exercise protein-containing drink on gastric motility and energy intake in healthy young men.

The present study examined the effects of different temperatures of protein-containing drink after exercise on subsequent gastric motility and energy intake in healthy young men. Twelve healthy young men completed three, 1-d trials in a random order. In all trials, the subjects ran on a treadmill for 30 min at 80% of maximum heart rate. In exercise + cold drink (2°C) and exercise + hot drink (60°C) trials, the subjects consumed 300 ml of protein-containing drink (0·34 MJ) at 2°C or 60°C over a 5-min period after exercise. In the exercise (i.e. no preload) trial, the subjects sat on a chair for 5 min after exercise. Then, the subjects sat on a chair for 30 min to measure their gastric motility with an ultrasound imaging system in all trials. Thereafter, the subjects consumed a test meal until they felt comfortably full. Energy intake in the exercise + hot drink trial was 14 % and 15 % higher than the exercise (P = 0·046, 95% CI 4·010, 482·538) trial and exercise + cold drink (P = 0·001, 95% CI 160·089, 517·111) trial, respectively. The frequency of the gastric contractions in the exercise + hot drink trial was higher than the exercise (P = 0·023) trial and exercise + cold drink (P = 0·007) trial. The total frequency of gastric contractions was positively related to energy intake (r = 0·386, P = 0·022). These findings demonstrate that consuming protein-containing drink after exercise at 60°C increases energy intake and that this increase may be related to the modulation of the gastric motility.

Effects of oral cystine and glutamine on exercise-induced changes in gastrointestinal permeability and damage markers in young men.

PURPOSE: Although acute prolonged strenuous exercise has been shown to increase markers of gastrointestinal permeability and damage, little is known regarding the efficacy of nutritional supplement interventions on the attenuation of exercise-induced gastrointestinal syndrome. This study addressed the effects of oral amino acid supplementation on markers of gastrointestinal permeability and damage in response to exercise. METHODS: Sixteen active men aged 22.7 ± 2.6 years (mean ± standard deviation) completed placebo or cystine and glutamine supplementation trials in random order. Participants received either a placebo or cystine and glutamine supplements, three times a day for 5 days, separated by a 2-week washout period. On day 6, participants took their designated supplements 30 min before running at a speed corresponding to 75% of maximal oxygen uptake for 1 h, followed by a 4-h rest period. Blood samples were collected pre-exercise, immediately post-exercise, 30 min post-exercise, and 1, 2 and 4 h post-exercise on day 6. The plasma lactulose to mannitol ratio (L:M) and plasma intestinal fatty acid-binding protein (I-FABP) were used as markers of gastrointestinal permeability and damage, respectively. RESULTS: Plasma L:M (linear mixed model, coefficient ± standard error: - 0.011 ± 0.004, P = 0.0090) and changes (i.e., from pre-exercise) in plasma I-FABP (linear mixed model, - 195.3 ± 65.7 coefficient ± standard error (pg/mL), P = 0.0035) were lower in the cystine and glutamine supplementation trial than in the placebo trial. CONCLUSION: Oral cystine and glutamine supplementation attenuated the markers of gastrointestinal permeability and damage after 1 h of strenuous running in young men. TRIAL REGISTRATION NUMBER: UMIN000026008. DATE OF REGISTRATION: 13 December 2018.

Does butyrylcholinesterase mediate exercise-induced and meal-induced suppression in acylated ghrelin?

Ample evidence supports the notion that an acute bout of aerobic exercise and meal consumption reduces acylated ghrelin concentration. However, the mechanisms by which this exercise- and meal-induced suppression of acylated ghrelin occurs in humans is unknown. This study aimed to examine the concentration of butyrylcholinesterase (BChE), an enzyme responsible for hydrolysing ghrelin and other appetite-related hormones in response to a single bout of running and a standardised meal in young, healthy men. Thirty-three men (aged 23 ± 2 years, mean ± standard deviation) underwent two (exercise and meal conditions) 2-h laboratory-based experiments. In the exercise condition, all participants ran for 30 min at 70% of the maximum oxygen uptake (0930-1000) and rested until 1130. In the meal condition, participants reported to the laboratory at 0930 and rested until 1000. Subsequently, they consumed a standardised meal (1000-1015) and rested until 1130. Blood samples were collected at baseline (0930), 1000, 1030, 1100 and 1130. BChE concentration was not altered in both the exercise and meal conditions (p > 0.05). However, acylated ghrelin was suppressed after exercise (p < 0.05) and meal consumption (p < 0.05). There was no association between the change in BChE concentration and the change in acylated ghrelin before and after exercise (p = 0.571). Although des-acylated ghrelin concentration did not change during exercise (p > 0.05), it decreased after meal consumption (p < 0.05). These findings suggest that BChE may not be involved in the suppression of acylated ghrelin after exercise and meal consumption.

The effects of acute and chronic oral l-arginine supplementation on exercise-induced ammonia accumulation and exercise performance in healthy young men: A randomised, double-blind, cross-over, placebo-controlled trial.

Objective: This study examined the effects of a single and chronic oral intake of l-arginine supplementation on blood ammonia concentration and exercise performance. Methods: Sixteen healthy young men (mean ± standard deviation, 23 ± 3 years) participated in a randomised, double-blind, cross-over, placebo-controlled study. For the acute trials, the participants consumed 200 mL of water containing either l-arginine (5 g) or placebo (dextrin; 5.5 g) and performed cycling exercise at 75% of heart rate reserve for 60 min, followed by a 15-min cycling performance test. For the chronic trials, the participants continued to consume each designated supplement twice a day for another 13 days, and then repeated the same protocol as the acute trials at day 15. After a 14-day washout period, the participants changed the supplement and repeated the same protocol as above. Results: Plasma ammonia concentrations were lower in the chronic arginine trial than those in both acute placebo (mean difference - 4.5 µmol/L) and acute arginine (mean difference - 5.1 µmol/L) trials (p < 0.05). There was no difference in plasma ammonia concentration between the chronic arginine and chronic placebo trials (mean difference - 1.2 µmol/L). No differences were found in mean power output during the performance test between the chronic arginine and chronic placebo trials (mean difference 0.5 W) or between the acute arginine and acute placebo trials (mean difference 0.0 W). Conclusions: An acute and chronic oral intake of l-arginine supplementation did not attenuate exercise-induced increases in ammonia accumulation or had no significant impact on cycling performance.

Postprandial Metabolism and Physical Activity in Asians: A Narrative Review.

The widespread benefits of physical activity in enhancing health and lowering the risk of non-communicable chronic diseases are well established across populations globally. Nevertheless, the prevalence of several lifestyle-related chronic diseases, including cardiovascular disease, varies markedly across countries and ethnicities. Direct ethnic comparative studies on the health benefits of physical activity are sparse and evidence-based physical activity guidelines are not ethnicity-specific. Indeed, physical activity guidelines in some Asian countries were developed primarily based on data from Western populations even though the magnitude of potential benefit may not be the same among different ethnic groups. Unfavorable diurnal perturbations in postprandial triglycerides and glucose are risk factors for cardiovascular disease. This narrative review summarizes differences in these risk factors primarily between individuals of Asian and white European descent but also within different Asian groups. Moreover, the variable effects of physical activity on mitigating risk factors among these ethnic groups are highlighted along with the underlying metabolic and hormonal factors that potentially account for these differences. Future ethnic comparative studies should include investigations in understudied ethnic groups, such as those of East Asian origin, given that the effectiveness of physical activity for ameliorating cardiovascular disease varies even among Asian groups.

Frequency of interruptions to prolonged sitting and postprandial metabolic responses in young, obese, Chinese men.

This study aimed to examine the effects of 3-min light-intensity walking every 30 min (3-min) and 6-min light-intensity walking every 60 min (6-min) compared with prolonged sitting (SIT) on the postprandial metabolic responses in young, centrally obese, Chinese men. Twenty-one Chinese men with central obesity (age, 23 ± 4 years; body mass index, 29.8 ± 3.2 kg·m-2; waist circumference, 98.7 ± 7.1 cm; mean ± SD) underwent three 6-h experiments with a 7-day washout period, SIT, 3-min, and 6-min, in randomized order. Compared with SIT, neither walking condition showed differences in total and net incremental area under the curve (tAUC and iAUC, respectively) for glucose, insulin, nor non-esterified fatty acids. The tAUC and iAUC for triglycerides for the SIT condition (10.8 [9.3, 12.2] and 4.4 [3.7, 5.1] mmol·h·L-1, respectively; mean [95% confidence interval]) was higher than 3-min (10.4 [9.0, 11.8] and 3.8 [3.3, 4.3] mmol·h·L-1, respectively, both Ps <0.05) and 6-min (9.6 [8.1, 11.0] and 3.5 [2.9, 4.2] mmol·h·L-1, respectively, both Ps <0.01) conditions. Interrupting prolonged sitting regardless of frequency-reduced postprandial triglycerides. A higher volume of physical activity may be required to obtain greater glycaemic benefits in young Chinese men with central obesity.

The chronic effect of physical activity on postprandial triglycerides in postmenopausal women: A randomized controlled study.

OBJECTIVE: This study examined the chronic effect of increased physical activity on postprandial triglycerides in older women. METHODS: Twenty-six women, aged 72 ± 5 years (mean ± SD), participated in this study. Participants in the physical activity group (n = 11) were asked to increase their activities above their usual lifestyle levels for 12 weeks. Participants in the control group (n = 15) maintained their usual lifestyle for 12 weeks. All participants rested and consumed a standardized breakfast after a 24-h period of physical activity avoidance at baseline, 4 weeks, and 12 weeks. Blood samples were collected in the fasted state (0 h) and at 2, 4, and 6 h after breakfast. RESULTS: The average increased time spent in self-selected activities per day was 1.1 ± 19.3 min over the 12 weeks compared with the baseline in the physical activity group. There was no difference in the postprandial time-averaged triglyceride area under the curve at baseline (1.59 ± 0.81 vs. 1.39 ± 0.67 mmol/L, p = 0.515) or over the 12-week intervention (1.78 ± 1.00 vs. 1.31 ± 0.67 mmol/L, p = 0.212) between the physical activity and control groups. CONCLUSION: Postprandial triglyceride concentrations were not reduced after performing self-selected activities under free-living conditions in older women when these responses were determined 24 h after the last physical activity bout. (Trial registration ID: UMIN000037420).

Gum chewing while walking increases walking distance and energy expenditure: A randomized, single-blind, controlled, cross-over study.

BACKGROUND/OBJECTIVE: Gum chewing while walking increases walking distance and energy expenditure in middle-aged male and female individuals. This study aimed to examine the effects of gum chewing while walking on walking distance and energy metabolism in male and female individuals of various age groups. METHODS: Fifty participants (25 male and 25 female individuals) aged 22-69 years completed two trials in a random order. In the gum trial, participants walked at a natural pace for 15 min while chewing two gum pellets (1.5 g, 3 kcal per pellet) following a 50-min rest period. In the tablet trial, participants rested for 50 min before walking, and the participants then walked at a natural pace for 15 min after ingesting two pellets of tablet containing the same ingredients with the exception of the gum base. The walking distance, step count, walking speed, stride, heart rate, energy expenditure, and respiratory exchange ratio were measured. RESULTS: Walking distance, step count, walking speed, heart rate, and energy expenditure during walking were significantly higher in the gum trial than in the tablet trial. In participants aged ≥40 years, walking distance, walking speed, stride, heart rate, and energy expenditure during walking were significantly increased during the gum trial compared with those during the tablet trial. CONCLUSION: The study findings demonstrated that gum chewing while walking increased walking distance and energy expenditure in both male and female individuals.

The effects of water temperature on gastric motility and energy intake in healthy young men.

PURPOSE: Although immediate pre-meal water ingestion has been shown to reduce energy intake in healthy young men, no studies are available regarding potential mechanisms underlying the effect of energy intake in response to different temperatures of pre-meal water ingestion. This study examined the effects of consuming different temperatures of water on gastric motility and energy intake in healthy young men. METHODS: Eleven young men were completed three, 1-day trials in a random order. Subjects visited the laboratory after a 10-h overnight fast and consumed 500 mL of water at 2 °C, 37 °C, or 60 °C in 5 min. Then, subjects sat on a chair over 1 h to measure the cross-sectional gastric antral area and gastric contractions using the ultrasound imaging systems. Thereafter, subjects consumed a test meal until they felt completely full. Energy intake was calculated from the amount of food consumed. RESULTS: Energy intake in the 2 °C (6.7 ± 1.8 MJ) trial was 19% and 26% lower than the 37 °C (7.9 ± 2.3 MJ, p = 0.039) and 60 °C (8.5 ± 3.2 MJ, p = 0.025) trials, respectively. The frequency of the gastric contractions after 1-h consuming water was lowered in the 2 °C trial than the 60 °C trial (trial-time interaction, p = 0.020). The frequency of gastric contractions was positively related to energy intake (r = 0.365, p = 0.037). CONCLUSIONS: These findings demonstrate that consuming water at 2 °C reduces energy intake and this reduction may be related to the modulation of the gastric motility.

Correction to: Energy replacement diminishes the postprandial triglyceride­lowering effect from accumulated walking in older women.

The original version of this article unfortunately contained a mistake. The error of NEFA AUC values in first (mean and 95% CI) and the main text (effect size and 95% CI).

Energy replacement diminishes the postprandial triglyceride-lowering effect from accumulated walking in older women.

PURPOSE: Dietary replacement of an acute exercise-induced energy deficit offsets the postprandial triglyceride (TG)-lowering effect of exercise in young boys and middle-aged men. It is unclear whether these findings are observed when exercise is accumulated in older adults. This study examined the effect of accumulating short bouts of exercise, with and without dietary replacement of an exercise-induced energy deficit, on postprandial TG in older women. METHODS: Seventeen older women (≥ 65 years) underwent three, 8-h trials: (1) control, (2) accumulated walking and (3) accumulated walking with energy replacement. During the control trial, participants rested for 8 h. The accumulated walking trials comprised twenty 1.5 min brisk walking bouts performed at a pre-determined self-selected pace separated by 15 min seated rest. In each trial, participants consumed a standardised breakfast and lunch. The breakfast in the accumulated walking with energy replacement trial included replacement of the energy deficit (0.62 MJ, 149 kcal) induced by exercise. Venous blood samples were collected fasted and at 2, 4, 6 and 8 h after breakfast. RESULTS: Time-averaged postprandial serum TG concentrations over 8 h were lower after accumulated walking than control and accumulated walking with energy replacement (mean ± SD: 1.46 ± 0.93 vs 1.71 ± 1.01 vs 1.60 ± 0.98 mmol/L, respectively: main effect of trial p = 0.017). There was little difference between control and accumulated walking with energy replacement. CONCLUSIONS: Replacing the energy expenditure induced by accumulating 30 min of brisk walking in short (1.5 min) bouts diminishes the postprandial TG-lowering effect in older women.

Increased Urinary 3-Mercaptolactate Excretion and Enhanced Passive Systemic Anaphylaxis in Mice Lacking Mercaptopyruvate Sulfurtransferase, a Model of Mercaptolactate-Cysteine Disulfiduria.

Mercaptopyruvate sulfurtransferase (Mpst) and its homolog thiosulfate sulfurtransferase (Tst = rhodanese) detoxify cyanide to thiocyanate. Mpst is attracting attention as one of the four endogenous hydrogen sulfide (H2S)/reactive sulfur species (RSS)-producing enzymes, along with cystathionine ß-synthase (Cbs), cystathionine γ-lyase (Cth), and cysteinyl-tRNA synthetase 2 (Cars2). MPST deficiency was found in 1960s among rare hereditary mercaptolactate-cysteine disulfiduria patients. Mpst-knockout (KO) mice with enhanced liver Tst expression were recently generated as its model; however, the physiological roles/significances of Mpst remain largely unknown. Here we generated three independent germ lines of Mpst-KO mice by CRISPR/Cas9 technology, all of which maintained normal hepatic Tst expression/activity. Mpst/Cth-double knockout (DKO) mice were generated via crossbreeding with our previously generated Cth-KO mice. Mpst-KO mice were born at the expected frequency and developed normally like Cth-KO mice, but displayed increased urinary 3-mercaptolactate excretion and enhanced passive systemic anaphylactic responses when compared to wild-type or Cth-KO mice. Mpst/Cth-DKO mice were also born at the expected frequency and developed normally, but excreted slightly more 3-mercaptolactate in urine compared to Mpst-KO or Cth-KO mice. Our Mpst-KO, Cth-KO, and Mpst/Cth-DKO mice, unlike semi-lethal Cbs-KO mice and lethal Cars2-KO mice, are useful tools for analyzing the unknown physiological roles of endogenous H2S/RSS production.

The effects of isomaltulose ingestion on gastric parameters and cycling performance in young men.

BACKGROUND/OBJECTIVE: Isomaltulose is a disaccharide with a low glycaemic index and plays a role in maintaining postprandial glucose. The maintenance of glucose availability during prolonged exercise has been shown to enhance exercise performance. The present study compared the effects of pre-exercise isomaltulose versus maltodextrin ingestion on gastric parameters and cycling performance in young men. METHODS: Fourteen young men (mean ±â€¯S.D., age 23 ±â€¯2 years) performed 60 min of continuous cycling at 75% of maximum heart rate followed by a 15-min exercise performance test while ingesting a 500-mL of water containing 100 mg of 13C-sodium acetate with either 50 g of isomaltulose or 50 g of maltodextrin. Gastrointestinal discomfort was assessed periodically using an 11-point visual analogue scale throughout the study. The gastric emptying rate was evaluated periodically with the 13C-sodium acetate breath test. For the exercise performance test, participants were instructed to pedal a cycle ergometer, exerting as much effort as possible at a self-selected pace. RESULTS: Plasma glucose and insulin concentrations measured at 30 min after ingestion were lower in the isomaltulose trial than in the maltodextrin trial. There were no differences in mean power output during the exercise performance test, gastric emptying rate or the subjective feelings of gastrointestinal discomfort between both trials. CONCLUSION: Under the current exercise protocol, pre-exercise ingestion of isomaltulose compared with maltodextrin provided no additional benefit relative to gastric emptying or aerobic exercise performance. Both isomaltulose and maltodextrin ingestion did not influence gastrointestinal distress during 60 min of cycling and performance test.

Gum chewing while walking increases fat oxidation and energy expenditure.

[Purpose] Although gum chewing while walking has been reported to increase walking speed and heart rate, its effect on energy expenditure remains unclear. The purpose of the present study was to investigate the effects of gum chewing while walking on fat oxidation, energy expenditure, and different walking parameters. [Participants and Methods] This randomized crossover study included 10 males and 5 females who walked for 15 min at their own pace while chewing 2 pieces of gum in the gum trial or while eating 2 tablets in the control trial. A wearable metabolic system, heart rate monitor, and pedometer measured fat oxidation, energy expenditure, heart rate, step count, and walking distance. Walking speed and stride length were also calculated. [Results] The energy expenditure, fat oxidation and heart rate were significantly higher during the gum trial than during the control trial. Significant increases were observed in the step count, walking distance, and walking speed but not in the stride length. [Conclusion] Our results suggest that gum chewing affects sympathetic nervous system activity and walking rhythm with a consequent improvement in the health-related effects of walking, which in turn helps to maintain weight. These findings may play a role in preventing the gradual age-related weight gain that predisposes to obesity.

Effects of increased daily physical activity on mental health and depression biomarkers in postmenopausal women.

[Purpose] Little is known about the effectiveness of daily physical activity on depression biomarkers in older adults. This study aimed to investigate the effects of increased daily physical activity for 8 weeks on depression biomarkers in postmenopausal women. [Participants and Methods] Thirty-eight postmenopausal females were randomly assigned into a control or an active group and were asked to wear a uniaxial accelerometer for 8 weeks. Blood samples were obtained at baseline and at the end of the intervention. During the intervention, the active group was asked to increase their physical activity level above their usual lifestyle whereas those in the control group maintained their daily lifestyle. [Results] After the 8-week intervention, the step counts of the participants in the active group increased. The serum concentration of the brain-derived neurotrophic factor and serotonin increased significantly in the active group, but not in the control group, as compared with baseline values. The serum concentration of derivatives of reactive oxygen metabolites and biological antioxidant potential did not change after the intervention in either group. [Conclusion] These findings may suggest that promotion of daily physical activity in postmenopausal women has a positive impact on depression without any change in oxidative stress.

Halftime Rewarm-up With Intermittent Exercise Improves the Subsequent Exercise Performance of Soccer Referees.

Yanaoka, T, Yamagami, J, Kidokoro, T, Kashiwabara, K, and Miyashita, M. Halftime rewarm-up with intermittent exercise improves the subsequent exercise performance of soccer referees. J Strength Cond Res 32(1): 211-216, 2018-This study investigated the effect of halftime rewarm-up (RW) with intermittent exercise on the subsequent exercise performance of soccer referees, determined by the Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1). Using a randomized cross-over design, 10 male referees were required to complete 2 trials. The trials consisted of the Loughborough Intermittent Shuttle Test, halftime, and Yo-Yo IR1 periods. During halftime, participants either rested on a chair (Control) or performed a halftime RW exercise for 15 minutes. The halftime RW protocol comprised 2.15 minutes of seated rest, followed by 2.15 minutes of running at 70% of the maximum heart rate (HRmax)-this cycle of recovery and running was repeated for a total of 13 minutes. The halftime RW protocol started at 1 minute after the commencement of the halftime period and concluded 1 minute before its end. The Yo-Yo IR1 performance, blood glucose, free fatty acids (FFAs), triglycerides (TGs), creatine kinase (CK), and lactate concentrations, the rating of perceived exertion, mean HR, and HRmax were analyzed. The Yo-Yo IR1 performance was higher in the halftime RW trial than in the control trial (3,095 ± 326 vs. 2,904 ± 421 m, P ≤ 0.05). The mean HR and HRmax, blood glucose, FFA, TG, CK, and lactate concentrations did not differ between the trials. The rating of perceived exertion during the halftime RW, but not after the Yo-Yo IR1 period, was higher than that in the control trial. In conclusion, this study showed that halftime RW with intermittent exercise improves the subsequent exercise performance.

Very-Short-Duration, Low-Intensity Half-Time Re-warm up Increases Subsequent Intermittent Sprint Performance.

Yanaoka, T, Hamada, Y, Kashiwabara, K, Kurata, K, Yamamoto, R, Miyashita, M, and Hirose, N. Very-short-duration, low-intensity half-time re-warm up increases subsequent intermittent sprint performance. J Strength Cond Res 32(11): 3258-3266, 2018-This study investigated the effect of very-short-duration, low-intensity half-time re-warm up (RW) on subsequent intermittent sprint performance. Using a randomized cross-over design, 11 healthy men performed 3 trials. In the experimental trials, participants performed the first 40-minute intermittent exercise followed by a 15-minute half-time. The interventions at half-time were 15 minutes of seated rest (control), 3 minutes of moderate-intensity RW (cycling at 60% of maximal oxygen uptake [V[Combining Dot Above]O2max]; [60% RW]), and 3 minutes of low-intensity RW (cycling at 30% of V[Combining Dot Above]O2max; [30% RW]). After half-time, participants performed the Cycling Intermittent-Sprint Protocol (CISP), which consisted of 10 seconds of rest, 5 seconds of maximal sprint, and 105 seconds of active recovery at 50% of V[Combining Dot Above]O2max, with the cycles repeated over the 20-minute duration. The mean work and electromyogram amplitude during the sprint in the CISP were higher in both RW trials than in the control trial (p < 0.05). Muscle temperature, estimated from the skin temperature, at 60 minutes was higher in the 60% RW trial than in the control and 30% RW trials (p < 0.05). The mean change in oxygenated hemoglobin concentration during active recovery at 55-65 minutes tended to be higher in both RW trials than in the control trial (60% RW trial: p = 0.06, 30% RW trial: p = 0.06). In conclusion, very-short-duration, low-intensity RW increased intermittent sprint performance after the half-time, in comparison with a traditional passive half-time practice, and was as effective as a moderate-intensity RW when matched for total duration.

The Effect of Half-time Re-Warm up Duration on Intermittent Sprint Performance.

The purpose of the present study was to investigate the effect of different durations of half-time re-warm up (RW) on intermittent sprint performance. Using a randomized crossover design, 13 healthy men performed three trials, which consisted of two, 40-min intermittent exercises separated by a 15-min half-time. Half-time interventions were 15 min of seated rest (Control), 7 min of cycling at 70% of maximal heart rate (HRmax) (7 min RW), and 3 min of cycling at 70% of HRmax (3 min RW). The second 40-min intermittent exercise as an exercise performance test was the Cycling Intermittent-Sprint Protocol (CISP), which consisted of 10 s of rest, 5 s of maximal sprint, and 105 s of low-intensity exercise at 50% of VO2max, with the cycles repeated over the 40-min duration. The mean work during the maximal sprint in the initial 10 min of the CISP was higher in the both RW trials than in the control trial (control: 3638 ± 906 J, 7 min RW: 3808 ± 949 J, p < 0.05, 3 min RW: 3827 ± 960 J, p < 0.05). There were no significant differences among three trials for mean work at 10-20, 20-30, and 30-40 min of the CISP. In the initial 10 min of the CISP, the change in oxygenated hemoglobin concentration during the 105 s of exercise at 50% of VO2max, oxygen uptake, carbon dioxide production, and respiratory exchange ratio were higher in both RW trials than in the control trial (p < 0.05). The rating of perceived exertion after half-time interventions was higher in both RW trials than in the control trial (p < 0.05). In conclusion, the 3 min RW increased intermittent sprint performance after the half-time, compared with a traditional passive half-time practice, and was as effective in improving intermittent sprint performance as the 7 min RW.