Hr Post Exercise Research Articles

Repeated-Sprint Exercise in the Heat Increases Indirect Markers of Gastrointestinal Damage in Well-Trained Team-Sport Athletes.

Athletes engaged in repeated-sprint training in the heat can be at an increased risk of gastrointestinal ischemia and damage in response to a redistribution of blood to working skeletal muscles and the skin. This study investigated the effects of repeated sprinting in hot and cool conditions on markers of gastrointestinal damage. Twenty-five, well-trained, nonheat acclimated male team-sport athletes completed a five-session, repeated-sprint training regimen over 7 days in either HOT (40 °C and 40% relative humidity [RH]) or COOL (20 °C and 40% RH) conditions. Participants underwent a 20-min warm-up and four sets of 5 × 6-s maximal cycling sprints, with 24-s rest and 5-min recovery between sets. Venous blood was collected pre-, post-, and 1hr postexercise and analyzed for intestinal fatty acid binding protein, lipopolysaccharide binding protein, soluble CD14, and heat-shock protein. Intestinal fatty acid binding protein concentrations were significantly increased (p < .004) postexercise (593 and 454pg/ml) and 1hr postexercise (466 and 410pg/ml) on both Days 1 and 5 in HOT. Soluble CD14 increased by 398 and 308ng/ml postexercise (p = .041), and lipopolysaccharide binding protein increased by 1,694ng/ml postexercise on Day 1 in HOT (p < .05) and by 1,520ng/ml on Day 5 in COOL (p = .026). Core and skin temperature, rating of perceived exertion, and thermal sensation were higher (p < .05) in HOT on Days 1 and 5 during sprinting. Repeated sprinting in the heat induced greater thermal strain and mild changes in gastrointestinal damage, likely attributable to the combination of environmental conditions and maximal-intensity exercise.

Exercise and Heat Stress: Inflammation and the Iron Regulatory Response.

This study determined the impact of heat stress on postexercise inflammation and hepcidin levels. Twelve moderately trained males completed three, 60-min treadmill running sessions under different conditions: (a)COOL, 18 °C with speed maintained at 80% maximum heart rate; (b)HOTHR, 35 °C with speed maintained at 80% maximum heart rate; and (c)HOTPACE, 35 °C completed at the average running speed from the COOL trial. Venous blood samples were collected pre-, post-, and 3-hr postexercise and analyzed for serum ferritin, interleukin-6 (IL-6), and hepcidin concentrations. Average HR was highest during HOTPACE compared with HOTHR and COOL (p < .001). Running speed was slowest in HOTHR compared with COOL and HOTPACE (p < .001). The postexercise increase in IL-6 was greatest during HOTPACE (295%; p = .003). No differences in the IL-6 response immediately postexercise between COOL (115%) and HOTHR (116%) were evident (p = .992). No differences in hepcidin concentrations between the three trials were evident at 3hr postexercise (p = .407). Findings from this study suggest the IL-6 response to exercise is greatest in hot compared with cool conditions when the absolute running speed was matched. No differences in IL-6 between hot and cool conditions were evident when HR was matched, suggesting the increased physiological strain induced from training at higher intensities in hot environments, rather than the heat per se, is likely responsible for this elevated response. Environmental temperature had no impact on hepcidin levels, indicating that exercising in hot conditions is unlikely to further impact transient alterations in iron regulation, beyond that expected in temperate conditions.

Sustained Exposure to High Carbohydrate Availability Does Not Influence Iron-Regulatory Responses in Elite Endurance Athletes.

This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17-23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3hr postexercise.

Ten Days of Curcumin Supplementation Attenuates Subjective Soreness and Maintains Muscular Power Following Plyometric Exercise

Curcumin has become a popular product used to decrease inflammation and enhance recovery from exercise. Purpose: To determine the effects of curcumin supplementation on delayed onset muscle soreness and muscle power following plyometric exercise. Methods: Participants (n = 22; five females, 17 males) consumed either curcumin (500 mg) or placebo twice daily for 10 days (6 days pre, day of and 3 days post exercise). Participants completed 5 x 20 drop jumps on day 7. Blood sampling and recovery tests were assessed at pre-supplementation, 24-hours and immediately pre-exercise, and immediately post-, 24, 48 and 72-hours post-exercise. Blood markers included serum creatine kinase (CK) and erythrocyte sedimentation rate (ESR), while soreness was measured during a squat and post vertical jump. Results: Both groups experienced muscle damage post-exercise with elevated CK (403 ± 390 ul; p < 0.01), soreness with squatting (38 ± 29 mm; p < 0.01), and vertical jump (36 ± 30 mm; p < 0.01). Soreness was greater in placebo vs. curcumin 48 h and 72 h post-exercise (p < 0.01); however, CK was not significantly different between groups (p = 0.28) despite being >200 IU·L −1 greater 24 hr post exercise in placebo vs. curcumin. ESR was significantly greater immediately post-exercise (6.3 ± 5.6 vs. 3.4 ± 2.6 mm/hr; p = 0.03), however these were within the normal range for this test and not significantly different between groups (p = 0.25). Vertical jump decreased over time in the placebo, but not curcumin group (19.8 ± 4.8 vs. 21.4 ± 3.2 in; p = 0.01). Conclusion: These data suggest curcumin reduces soreness and maintains muscular power following plyometric exercise.

Postexercise Inflammasome Activation and IL-1β Production Mitigated by Flavonoid Supplementation in Cyclists.

Inflammasomes are multiprotein signaling platforms of the innate immune system that detect markers of physiological stress and promote the maturation of caspase-1 and interleukin 1 beta (IL-1β), IL-18, and gasdermin D. This randomized, cross-over trial investigated the influence of 2-week mixed flavonoid (FLAV) versus placebo (PL) supplementation on inflammasome activation and IL-1β and IL-18 production after 75-km cycling in 22 cyclists (42 ± 1.7years). Blood samples were collected before and after the 2-week supplementation, and then 0hr, 1.5hr, and 21hr postexercise (176 ± 5.4min, 73.4 ± 2.0 %VO2max). The supplement (678mg FLAVs) included quercetin, green tea catechins, and bilberry anthocyanins. The pattern of change in the plasma levels of the inflammasome adaptor oligomer ASC (apoptosis-associated speck-like protein containing caspase recruitment domain) was different between the FLAV and PL trials, with the FLAV ASC levels 52% lower (Cohen's d = 1.06) than PL immediately following 75-km cycling (interaction effect, p = .012). The plasma IL-1β levels in FLAV were significantly lower than PL (23-42%; Cohen's d = 0.293-0.644) throughout 21hr of recovery (interaction effect, p = .004). The change in plasma gasdermin D levels were lower immediately postexercise in FLAV versus PL (15% contrast, p = .023; Cohen's d = 0.450). The patterns of change in plasma IL-18 and IL-37 did not differ between the FLAV and PL trials (interaction effects, p = .388, .716, respectively). These data indicate that 2-week FLAV ingestion mitigated inflammasome activation, with a corresponding decrease in IL-1β release in cyclists after a 75-km cycling time trial. The data from this study support the strategy of ingesting high amounts of FLAV to mitigate postexercise inflammation.

Extracellular vesicular miRNA expression is not a proxy for skeletal muscle miRNA expression in males and females following acute, moderate intensity exercise.

Skeletal muscle and extracellular vesicle (EV) miRNA expression increases following acute endurance exercise. However, research to date has only been performed in males. The aim of this study was to describe the expression levels of a subset of miRNAs in EVs following acute exercise and compare it to skeletal muscle miRNA expression. Twelve males (age 22.9 ± 2.6 years, mean ± SD) and eight females (age 23.0 ± 3.4 years) cycled for 60 min at 70% VO2peak. Muscle biopsies and blood samples were collected at rest, immediately after and 3 hr after exercise. Acute exercise did not significantly alter the expression of miR‐1, miR‐16, miR‐23b and miR‐133a/b in EVs in males and females combined. There were no correlations between EV and skeletal muscle miRNA expression in any of the measured species at any time point. Exploratory analysis revealed differential miRNA responses to exercise between males and females. In males, a weak negative correlation was observed between skeletal muscle and EV miR‐16 expression immediately following exercise; however, the physiological relevance of this correlation is unknown. Additionally, when compared with values at rest, male skeletal muscle miR‐16 expression significantly increased immediately following exercise, whereas miR‐133a expression significantly decreased 3 hr post exercise. Our findings suggest that miRNAs isolated from EVs are not a proxy for skeletal muscle miRNA content. Our exploratory data is the first known evidence of sex‐specific differences in the miRNA response to an acute bout of endurance exercise, particularly for miRNA species implicated in mitochondrial metabolism and angiogenesis.

The Effects of a High-Protein Diet on Markers of Muscle Damage Following Exercise in Active Older Adults: A Randomized, Controlled Trial.

This study examined whether a higher protein diet following strenuous exercise can alter markers of muscle damage and inflammation in older adults. Using a double-blind, independent group design, 10 males and eight females (age 57 ± 4years; mass 72.3 ± 5.6kg; height 1.7 ± 6.5m) were supplied with a higher protein (2.50g·kg-1·day-1) or moderate protein (1.25g·kg-1·day-1) diet for 48hr after 140 squats with 25% of their body mass. Maximal isometric voluntary contractions, muscle soreness, creatine kinase, Brief Assessment of Mood Adapted, and inflammatory markers were measured preexercise, and 24hr and 48hr postexercise. The maximal isometric voluntary contractions decreased postexercise (p = .001, ηp2=.421), but did not differ between groups (p = .822, ηp2=.012). Muscle soreness peaked at 24hr post in moderate protein (44 ± 30mm) and 48hr post in higher protein (70 ± 46mm; p = .005; ηp2=.282); however, no group differences were found (p = .585; ηp2=.083). Monocytes and lymphocytes significantly decreased postexercise, and eosinophils increased 24hr postexercise (p < 0.05), but neutrophils, creatine kinase, interleukin-6, C-reactive protein, monocyte chemotactic protein-1, and Brief Assessment of Mood Adapted were unchanged by exercise or the intervention (p > .05). In conclusion, 2.50g·kg-1·day-1 of protein is not more effective than 1.25g·kg-1·day-1 for attenuating indirect markers of muscle damage and inflammation following strenuous exercise in older adults.

Effects Of Acute Short Sleep And High-intensity Interval Exercise On Heart Rate Variability Frequency Indices

Short sleep (SS) disrupts the normal functioning of the autonomic nervous system (ANS). Heart rate variability (HRV) is a reproducible measure of ANS function. Reduction in HRV represents a disruption of the ANS. High-intensity interval exercise (HIIE) reduces HRV. The immediate HRV response and its short-term recovery after HIIE is unexplored. SS prior to HIIE may disrupt further the ANS and reduce HRV. PURPOSE: To characterize the influence of SS on HRV after a single bout of HIIE in the hours post-exercise (PE). METHODS: Fifteen physically active males (age 31.1±5.3 yr) with good sleep quality as determined by the Pittsburgh Sleep Quality Index (PSQI) participated in this study. Participants completed a non-exercise control trial after 9 to 9.5 hrs of reference sleep (RS), a HIIE treadmill running (90% and 40% of VO2reserve in 3:2 min ratio) to expend 500 kcals after reference sleep (RSX) and after 3 to 3.5 hrs of SS (SSX) in a randomized crossover design. After being in a supine position for 10 minutes in a quiet and temperature-controlled environment heart rate (HR) was recorded for 5 minutes the night before, the morning of the next day, 1-, 2-, 4- and 6-hours PE using an elastic electrode belt (Polar Wearlink®). Sleep was performed at their own residence. Supine resting HRV indices (frequency domain: LF/HF and VLF) obtained from HR were measured and processed by CardioMood®. Data were analyzed using a 3 (condition) by 6 (time) repeated measures ANOVA. Examined variables violated normality and thus were transformed into natural logarithm (ln). Bonferroni was used for post hoc comparisons. Significance was set at p < 0.05. All analyses were performed using SPSS©. RESULTS: For ln VLF there was a main effect for condition by time interaction (F10,140=3.60, p=.000, η2=.204), but not for ln LF/HF condition by time (F10,140=1.84, p=.060, η2=.116). ln VLF was both decreased in RSX at 1hr PE (6.3+.25, p=.001) and 2hr PE (7.1+.20, p=.007) and in SSX 1hr PE (6.1+.22, p=.000) and 2hr PE (7.4+.26, p=.000) compared to RS. During post hocanalysis frequency domain ln LF/HF was increased in SSX at Day 2-baseline (.29+.17, p=.040) and at 1hr PE (1.1+.19, p=.041). CONCLUSION: HIIE with 3:2 min ratio decreases HRV for up to 2 hours PE and takes more than 6 hours to return to baseline levels. These responses are not modified by a single night of short sleep.

Carbohydrate Before Resistance Exercise Doesn't Alter Performance, Blood Glucose, Or Muscle Glycogen Despite Hormonal Changes

PURPOSE: The purpose of this study was to investigate changes in resistance exercise performance, serum insulin, epinephrine, glucose, and muscle glycogen from carbohydrate supplementation. METHODS: Participants completed four sets to failure at 70% of 1-RM with 45s rest on angled leg press with or without pre-exercise carbohydrate (2g/kg) after a 3hr fast. Serum glucose, epinephrine, and insulin were assessed at baseline, 30 min post-ingestion, immediately after, and 1hr post-exercise with or without carbohydrate supplementation. Muscle glycogen was measured at baseline, immediately after exercise, and 1hr post exercise. RESULTS: There was no main effect of supplement on resistance exercise performance (F= 2.169, p=.18). There was a main effect for set on repetitions showing a decrease over sets completed (F=26.18, p<.001) There was no interaction between supplement and set on reps to fatigue (F= .337, p=.79). There was a time effect showing glycogen decreased immediately post-exercise for both groups and remained lower than baseline after 1hr (F= 14.305, p<.001). No main effect of supplement on glycogen concentration was found (F=2.847, p=.13). No supplement time interaction was found on glycogen (F = 1.191, p=.33). There was an interaction showing pre-exercise carbohydrate supplementation led serum glucose to be utilized more during exercise (F= 3.791, p=.026). No main effect for supplementation on blood glucose was found (F= .072, p=.79). Pairwise comparisons indicated no time effect on serum glucose (p>.05). An interaction occurred showing insulin decreased during exercise in the carbohydrate condition (F= 47.14, p=.003). Also, there was a main effect of insulin being elevated with carbohydrate consumption (F= 7.72, p=.027). Pairwise comparisons indicated there was no time effect on insulin concentration (p>.05). There was a main effect of carbohydrate supplement decreasing epinephrine (F=7.924, p=.023). No time effect was found on epinephrine concentration (F=1.475, p=.258). No interaction effect was found on epinephrine (F=1.94, p=.181). CONCLUSIONS: Carbohydrate supplementation before resistance exercise does not improve leg press performance to fatigue or glycogen recovery during 1hr rest despite increased glucose availability.

Temporal Robustness Of The Srpe Method Of Monitoring Training

INTRODUCTION: Session Rating of Perceived Exertion (sRPE) has been used to monitor training as an alternative to traditional measures such as heart rate, blood lactate and VO2. sRPE has traditionally been measured ~30 min post exercise, although recent data suggest that it is temporally robust in the 5-min to 24 hr post exercise window. The goal of this study was to analyze the post-exercise on temporal robustness of sRPE as well as the difference between coach-intended RPE and athlete-reported sRPE. METHODS: Collegiate swimmers (n=15) (NCAA Division III) completed 5 training sessions at different coach intended levels of sRPE. The subjects reported sRPE ~30 min post-exercise and then 5 more times in the subsequent two weeks following each training session. RESULTS: Athletes reported similar sRPE over all times post-exercise for all workouts, suggesting that sRPE is a viable method of monitoring training up to 14 days post-exercise. The sRPE reported by the athletes were significantly lower than coach indented when the intended RPE was high (sRPE~9.0), and significantly higher than coach’s when intended sRPE sas lower (~4.0-5.0). CONCLUSIONS: The findings suggest that sRPE is very temporally robust, but that there is a mismatch between coach and athlete related to training intensity.

The Effect Of Blood Flow Restriction Resistance Training On Exercise-induced Hypoalgesia

PURPOSE: Exercise-induced hypoalgesia (EIH) describes a reduction in pain sensitivity following exercise, characterised by an elevation in pain threshold or decrease pain intensity ratings following exercise. Recent research suggests that performing light-load resistance exercise with blood flow restriction (BFR-RE) may have a pain-modulation effect. Therefore, the aim of this study was to compare the magnitude of EIH with BFR-RE to resistance exercise at both low and high intensities. METHODS: Twelve recreationally active individuals were recruited to participate. In a randomised crossover design, participants completed 4 experimental trials of resistance exercise ((1) light load resistance exercise (LLRE); (2) BFR-RE with low pressure (BFR40); (3) BFR-RE with high pressure (BFR80) and (4) heavy load resistance exercise (HLRE)). Pressure pain threshold (PPT) was then assessed at multiple body sites (dominant and non-dominant quadriceps and non-dominant trapezius muscle) pre, 5 min, 10 min and 24 hr post exercise. RESULTS: There was a two-way interaction effect for the dominant quadriceps site. Post-hoc analysis showed that, compared to LLRE, PPT was higher following BFR40, BFR80 and HLRE. PPT was higher following BFR80 compared to BFR40 and HLRE. At 24h post-exercise, PPTs were 14.5 ± 6.7% and 23.9 ± 8.2% higher than pre-exercise values in the BFR40 and BFR80 trials, respectively, whereas PPTs had returned to baseline in the LLRE and HLRE trials. Compared to LLRE, the increase in PPT was greater following BFR40 (0.28 ± 0.13 AU), BFR80 (0.64 ± 0.42 AU) and HLRE (0.34 ± 0.20 AU) in the non-dominant quadriceps. At 24h PPTs had returned to baseline. Compared to LLRE, the increase in PPT was greater following BFR40 (0.31 ± 0.27 AU), BFR80 (0.30 ± 0.17 AU), and HLRE (0.26 ± 0.13 AU) for the trapezius. At 24h PPTs had returned to baseline. CONCLUSIONS: In conclusion BFR with higher pressure leads to EIH in both dominant and non-dominant limbs suggesting both central and peripheral mechanisms of action.

679-P: Endothelial and Hematopoietic Progenitor Cells Are Reduced at Rest and Have an Attenuated Mobilization Response to Exercise in People with Type 1 Diabetes

Aims: Endothelial and Hematopoietic Progenitor Cells (EPCs and HPCs) promote vascular health through secreting proangiogenic factors and replacing damaged cells. Exercise has been shown to be a mobiliser of these rare cells in healthy individuals, however, the response in chronic diseases such as type 1 diabetes (T1D) is unclear. We compared EPC and HPC counts at rest and after acute exercise in people with and without T1D. Methods: Thirty T1D participants (38±12 years, HbA1c 58.5±9.3 mmol/mol-1, diabetes duration 20±13 years) and 30 age, sex, BMI and fitness matched non diabetes controls were recruited. After a maximal exercise test, participants attended a second visit to complete 45mins of walking at 60%VO2peak. Blood samples were taken at rest, immediately and 1 hour post exercise. Circulating levels of two HPCs and five EPC phenotypes were enumerated by flow cytometry. Data (mean±SD) were analysed by mixed model ANOVA and t-test with significance accepted at p≤0.05. Results: The T1D group had significantly lower rest count of HPCs and EPCs, ranging from 21 to 41% lower across all samples compared to the control. Exercise mobilized all cell phenotypes in both groups, with significant increases from rest to post exercise, while HPCs and CD34+CD31+ EPCs remained elevated 1hr post exercise. However, the change (Δ) in HPCs and EPCs from rest to post exercise was greater in the control versus T1D group, with higher CD34+CD45dim HPCs (p=0.03, Δ 48±65 vs. 24±33 cells/ml), as well as CD34+CD31+ (p=0.04, Δ 23±19 vs. 15±25 cells/ml) and CD34+VEGFR2+ EPCs (p=0.02, Δ 24 ±24 vs. 15±31 cells/ml). Conclusion: People with T1D have reduced numbers of HPCs and EPCs at rest and also display a blunted exercise induced increase in these rare blood vessel protecting cells. Further research is needed to understand the clinical significance of an attenuated exercise mobilization of these EPCs and HPCs phenotypes in predicting future cardiovascular complications in T1D. Disclosure G.S. Taylor: None. K. Smith: None. J. Scragg: None. A. Bashir: None. A. Flatt: None. E.J. Stevenson: None. J.A. Shaw: Advisory Panel; Self; Medtronic. Speaker’s Bureau; Self; Novo Nordisk A/S. M.D. Ross: None. D.J. West: None. Funding Diabetes Research &amp; Wellness Foundation (to D.J.W.)

93 Comparison of physiological responses to exercise in horses on a conditioning regimen versus inactive horses receiving a yucca and fenugreek dietary supplement

Abstract Yucca and fenugreek are purported to reduce inflammation and improve metabolic response to exercise. Therefore, we evaluated the effects of a dietary supplement (DigestaWell NRG) in unconditioned horses completing an exercise challenge test. In this study, 10 unfit horses were assigned to receive exercise (EXC; n = 5) or the dietary supplement (SUP; n = 5). Horses assigned to EXC were ridden daily at a walk, trot, and canter. Horses assigned to SUP were ridden once per week at a walk and slow trot, but received no other exercise. Horses underwent a 14-min standardized exercise test (5 min walk, 5 min trot, 4 min canter) prior to (Period1) and after a 4-wk treatment period (Period2). Heart rate, respiration rate, blood lactate concentrations, and thermal images of six muscle groups were obtained prior to, immediately after, and 2 hr post-test. Data were analyzed using repeated measures ANOVA. During Period1, similar (P &gt; 0.05) post-exercise increases in heart rate, respiration rate, blood lactate, and thermal images were observed regardless of treatment group. During Period2, SUP horses had lower (P &lt; 0.001) lactate concentrations than EXC horses at 2 hr post exercise, and it is possible that these lower concentrations are responsible for lower peripheral temperatures. Infrequently exercised horses may benefit from yucca and fenugreek supplementation due to the observed effect of these herbs to reduce post-exercise lactate concentrations and peripheral temperatures.

44 Comparison of physiological responses to exercise in horses on a conditioning regimen versus inactive horses receiving a yucca and fenugreek dietary supplement

Abstract Yucca and fenugreek are purported to reduce inflammation and improve metabolic response to exercise. Therefore, we evaluated the effects of a dietary supplement (DigestaWell NRG) in unconditioned horses completing an exercise challenge test. In this study, 10 unfit horses were assigned to receive exercise (EXC; n = 5) or the dietary supplement (SUP; n = 5). Horses assigned to EXC were ridden daily at a walk, trot, and canter. Horses assigned to SUP were ridden once per week at a walk and slow trot, but received no other exercise. Horses underwent a 14-min standardized exercise test (5 min walk, 5 min trot, 4 min canter) prior to (Period1) and after a 4-wk treatment period (Period2). Heart rate, respiration rate, blood lactate concentrations, and thermal images of six muscle groups were obtained prior to, immediately after, and 2 hr post-test. Data were analyzed using repeated measures ANOVA. During Period1, similar (P &gt; 0.05) post-exercise increases in heart rate, respiration rate, blood lactate, and thermal images were observed regardless of treatment group. During Period2, SUP horses had lower (P &lt; 0.001) lactate concentrations than EXC horses at 2 hr post exercise, and it is possible that these lower concentrations are responsible for lower peripheral temperatures. Infrequently exercised horses may benefit from yucca and fenugreek supplementation due to the observed effect of these herbs to reduce post-exercise lactate concentrations and peripheral temperatures.

Whey Protein Augments Leucinemia and Postexercise p70S6K1 Activity Compared With a Hydrolyzed Collagen Blend When in Recovery From Training With Low Carbohydrate Availability.

We examined the effects of whey versus collagen protein on skeletal muscle cell signaling responses associated with mitochondrial biogenesis and protein synthesis in recovery from an acute training session completed with low carbohydrate availability. In a repeated-measures design (after adhering to a 36-hr exercise-dietary intervention to standardize preexercise muscle glycogen), eight males completed a 75-min nonexhaustive cycling protocol and consumed 22g of a hydrolyzed collagen blend (COLLAGEN) or whey (WHEY) protein 45min prior to exercise, 22g during exercise, and 22g immediately postexercise. Exercise decreased (p < .05) muscle glycogen content by comparable levels from pre- to postexercise in both trials (≈300-150mmol/kg·dry weight). WHEY protein induced greater increases in plasma branched chain amino acids (p = .03) and leucine (p = .02) than COLLAGEN. Exercise induced (p < .05) similar increases in PGC-1α (fivefold) mRNA at 1.5hr postexercise between conditions, although no effect of exercise (p > .05) was observed for p53, Parkin, and Beclin1 mRNA. Exercise suppressed (p < .05) p70S6K1 activity in both conditions immediately postexercise (≈25fmol·min-1·mg-1). Postexercise feeding increased p70S6K1 activity at 1.5hr postexercise (p < .05), the magnitude of which was greater (p < .05) in WHEY (180 ± 105fmol·min-1·mg-1) versus COLLAGEN (73 ± 42fmol·min-1·mg-1). We conclude that protein composition does not modulate markers of mitochondrial biogenesis when in recovery from a training session deliberately completed with low carbohydrate availability. By contrast, whey protein augments postexercise p70S6K activity compared with hydrolyzed collagen, as likely mediated via increased leucine availability.

Relationship Between Autophagy and Heat Shock Response in Peripheral Blood Mononuclear Cells Following Resistance Exercise

Autophagy and protein degradation occur during the proximal hours (hr) post-exercise (PE) and are then followed by a gradual transition to protein synthesis. Previous works suggest that this biphasic relationship is mediated in-part by the heat shock response which may influence autophagy activity and may be influenced by the presence of amino acids. PURPOSE: To determine the effect of acute resistance exercise and branched-chain amino acid (BCAA) supplementation on autophagy and the heat shock response. METHODS: Twenty males (22.3±1.5yr, 86.4±15.6kg; 175.4±6.7cm) were randomly assigned to complete 8 days of 0.22 g/kg/d BCAA or placebo (PL) supplementation. On day 5 participants performed a bout of eccentric resistance exercise. Peripheral blood mononuclear cells (PBMC) were isolated pre-exercise, immediately post-exercise (IPE), and 2, 4, 24, 48, and 72hr. PBMC protein expression of autophagy markers (LC3I & II, & p62) and HSP70 were measured using Western blot. All autophagy and heat shock markers were assessed in relation to a standard baseline (1.0RQ). Red cell lysate was collected pre-exercise, IPE, and 1, 2, 4, and 24hr to assess glutathione/total glutathione ratio (GSSG/tGSH). RESULTS: No group differences (p>0.05) were detected for protein expression of autophagy markers, HSP70, or GSSG/tGSH ratio at any time-point. When combining groups, LC3II decreased significantly (p<0.01) at 2 (0.51±0.38RQ) and 4 (0.41±0.36RQ) hr PE. p62 decreased significantly (p<0.001) at IP (0.56±0.33RQ), 2 (0.24±0.23RQ), and 4 (0.33±0.31RQ) hr PE and significantly increased (p<0.01) at 24 (1.43±0.44RQ) hr PE. HSP70 increased significantly (p<0.001) increased at 48 (1.59±0.96RQ) and 72 (4.71±3.84RQ) hr PE. GSSG/tGSH ratio significantly (p<0.05) increased from baseline (0.11±0.04RQ) at 1 (0.39±0.05RQ), 2 (0.69±0.22RQ), and 4 (0.39±0.17RQ) hr post-exercise. CONCLUSION: These data support previous work that the heat shock response may exert regulatory control of autophagy in-part through HSP70. HSP70 may assist in transitioning the cell from an initial degradation phase immediately following exercise towards protein synthesis in the latter phases of the post-exercise period. The initial autophagy upregulation may be influenced by oxidative stress.

Acute Effects of Blood Flow Restriction Resistance Exercise in a Head-down Tilt Position on Growth Hormone and Insulin-like Growth Factor-I Release

Muscular atrophy is common among astronauts while in spaceflight. Growth Hormone (GH) and IGF-I are key hormones with regards to the preservation and growth of skeletal muscle tissue. Low intensity blood flow restriction (BFR) resistance exercise is a newer training modality employed to various populations to enhance muscle growth, yet has not been thoroughly explored in the astronaut population. PURPOSE: To determine the effects of low intensity BFR in a head-down tilt position on the acute release of GH and IGF-I. METHODS: Twelve college-aged males with resistance exercise experience were included in the study. The first of three sessions consisted of informed consent, demographic measurements, and 3RM testing. The two experimental sessions consisted of subjects resting in a -6 deg head-down tilt position for 2 hr. Upon rest completion, while tilted, subjects performed the exercise protocol at 30% of estimated 1RM for the following exercises: close-grip bench press, dumbbell bicep curls, and dumbbell triceps extensions. Exercises were performed with or without BFR (160 mmHg) to the upper arms in a counterbalanced order. Venus blood draws (15 mL) occurred 10 min prior to tilt, 10-15 min post exercise protocol, and 24 hr post exercise protocol and were assayed in duplicate. Two 2 x 2 Factorial ANOVAs with repeated measures were utilized for statistical analysis of the dependent variables (GH, IGF-I). Alpha levels were set at p < 0.05. RESULTS: A significant interaction was found between exercise condition and time for GH (p < .05). No significant interaction was found between exercise condition and time for IGF-I (p > .05). No significant mean difference was observed between BFR and no BFR for IGF-I (p >.05). A significant mean difference was observed pre to post exercise protocol for IGF-I (p < .05). CONCLUSION: A low intensity BFR exercise protocol in a head-down tilt position elicited a large increase in systemic GH concentrations from pre to post exercise. Post exercise GH levels were elevated to a much greater extent with BFR compared to no BFR. A low intensity BFR modality may be beneficial to employ to astronauts while in spaceflight or post spaceflight to help promote muscular tissue growth.

The Impact of Chocolate Goat's and Cow's Milk on Postresistance Exercise Endocrine Responses and Isometric Mid-Thigh Pull Performance

ABSTRACTThe present investigation examined the effects of chocolate cow's and goat's milk on endocrine responses and isometric mid-thigh pull performance post back squat exercise. Twelve college-aged males volunteered to participate and reported to the lab on four occasions. The first visit included anthropometric measurement, one-repetition back squat (1RM), and familiarization with the isometric mid-thigh pull assessment (IMTP). During the subsequent three visits, five sets of eight repetitions of the back squat exercise at 80% of 1RM were performed. For these trials, the participants performed an IMTP and gave a saliva sample prior to, immediately after, 1 hr and 2 hr post exercise. After exercise, a treatment of low-fat chocolate goat's milk (355 ml, 225 kcal), low-fat chocolate cow's milk (355 ml, 225 kcal), or control (water 355 ml, 0 kcal) was given in a counterbalanced order. Saliva samples were analyzed for testosterone, cortisol, and dehydroepiandrosterone (DHEA). Cortisol and DHEA hormone were unaffected by exercise; however, testosterone values did increase significantly post exercise. For IMTP, there was a significant main effect for time (F = 8.41, p = .007) but no treatment or interactions effects. N changes were noted post supplementation for cortisol or DHEA, but testosterone was found to be significantly reduced in both diary treatments compared to control (F = 4.27, p = .022). Based upon these data, it appears that a single treatment of chocolate goat's or cow's milk results in similar endocrine alterations but both fail to enhance postexercise isometric strength following resistance exercise.

Effect Of Obesity On Leukocyte Activation In Response To 1 Bout of High-Intensity Interval Exercise In Children

Adult and childhood obesity are associated with chronic inflammation. While exercise is known to improve cardiovascular health via modulation of inflammatory processes, including activation of circulating leukocytes (WBC), underlying biochemical mechanisms are not well defined, especially in children. Understanding these mechanisms may optimize effectiveness of exercise interventions. PURPOSE: To evaluate the extent of circulating WBC activation in obese and non-obese children during high-intensity interval cycling. METHODS: 12 obese (BMI >95% or Body fat % >35) and 9 non-obese children (10-17 yrs) underwent a high-intensity, cycle ergometer interval exercise challenge (10 sets of 2 min cycling at 80% peak VO2 + 1 min rest). Baseline, end-exercise, and 1 hour post-exercise blood samples were antibody-stained for cell surface marker analysis by flow cytometry. The inflammatory activation profile of neutrophils (Gc) was assessed by fluorescence intensity of CD11b, CD66b and CD62L. RESULTS: (see figure) At baseline, Gc CD11b expression was comparable across groups, but Gc counts were 31% greater (4.2±0.4 vs. 3.2±0.3 x1000/ul) in obese vs non-obese children. Both CD11b expression and Gc counts increased similarly in both groups at end-exercise, and resumed near-baseline values by 1 hr post exercise. CONCLUSION: While our experimental exercise format had similar effects on Gc counts and surface marker expression across groups, consistently higher cell counts indicate a greater exposure to pro-inflammatory stimuli in obese children. Investigating these responses across different exercise paradigms may help identify which exercise interventions display the most effective pattern of inflammatory modulation in pediatric obesity and other dysmetabolic conditions. Support: NIH Grants NICHD P01HD048721 & UL1 TR000153, UCI Newkirk Center

Influence of Habitual Carbohydrate Intake on Exercise‐Induced Inflammation in Ultra‐Endurance Athletes

Low carbohydrate diets (LCD) decrease systemic inflammatory markers in humans with chronic inflammation, such as obesity and metabolic syndrome; however it is unknown whether LCD can mitigate systemic inflammation in acute situations, such as exercise bouts.PurposeTo examine exercise‐induced alterations in inflammatory markers in elite ultra‐endurance athletes on a LCD or high carbohydrate diet (HCD).MethodsElite ultra‐endurance trained men (n=20, age 33.5±6.4yr VO2max 64.5±4.9mL/kg/min) habitually consuming a LCD (11% CHO, 71% FAT, 19% PRO) or HCD (58% CHO, 28% FAT, 15% PRO) completed a 3 hr treadmill run (65% VO2max). We measured circulating immune cells and select cytokines prior to, during, and post exercise (PE).ResultsEndurance exercise resulted in leukocytosis with elevated neutrophils, monocytes, and lymphocytes immediately PE with greater lymphocytes in LCD (LCD 2873.5±869.8; HCD 1904.7±825.9; cells/uL; p&lt;0.01). Neutrophils and monocytes remained elevated at 2 hr PE, while lymphocytes declined to below baseline levels. Circulating IL‐6 and IL‐8 increased 1 hr into exercise and remained elevated 2 hrs PE. IL‐10 increased 2 hrs into exercise and remained elevated 30 minutes PE. TNFa, IL‐1β, and IL‐12p70 did not change. Cytokines were not significantly different between groups.ConclusionEndurance exercise resulted in an acute inflammatory response. LCD did not significantly modulate the selected inflammatory markers. Ongoing research in our lab is examining additional markers of systemic inflammation, as well as potential muscle‐localized effects.