Bout Of Downhill Running Research Articles

MSM Supplementation Is Associated with Reduced Inflammation and Improved Innate Immune Response following In Vitro LPS-Stimulation in Humans after a Bout of Downhill Running

Exercise-induced muscle injury and the subsequent release of Damage-Associated Molecular Patterns (DAMP) result in soreness and inflammation. Dietary supplements may accelerate the rate of recovery by supporting resolution of inflammation. The purpose of this study was to determine if methylsulfonylmethane (MSM) supplementation (30 d prior to exercise and during recovery) altered mRNA expression in LPS-exposed blood leukocytes after a bout of downhill running. Exercise consisted of 60 min of downhill running (−15% grade). Blood (baseline, pre-exercise, 4, 24, 48, and 72 h post-exercise) was diluted (1:10) and combined with LPS (20 µg/mL) for 24 h. Total RNA was isolated from leukocytes and analyzed for 574 immune-associated mRNA (Nanostring nCounter; ROSALIND.BIO). Data were expressed as log2 fold change from baseline for each condition (MSM and placebo). Compared to placebo, MSM supplementation was associated with an improved inflammation response (15 mRNA) and viral immune response (2 mRNA). The largest number of changes were found at 4 and 24 h post-exercise. The key finding in the present study is that MSM supplementation can improve inflammation management and the innate immune response after exercise.

A single bout of downhill running attenuates subsequent level running-induced fatigue

Fatigue can be defined as exercise-induced strength loss. During running, fatigue can be partially explained by repetitive low-intensity eccentric contractions-induced muscle damage (EIMD). Previous studies showed that a bout of downhill running (DR) attenuated subsequent EIMD. Thus, we tested if a 30-min DR bout would attenuate fatigue induced by subsequent 60-min level running (LR). Twenty-seven male college students were randomly allocated to an experimental (EXP) or a control (CON) group. All participants performed LR on a treadmill at 70% of the velocity (vVO2peak) corresponding to peak oxygen uptake (VO2peak). Only EXP performed a 30-min DR (− 15%) on a treadmill at 70% vVO2peak fourteen days before LR. Indirect EIMD markers and neuromuscular function were assessed before, immediately and 48 h after DR and LR. Knee extension isometric peak torque (IPT) decreased (− 36.3 ± 26%, p < 0.05) immediately following DR with full recovery reached 48 h post-DR. Muscle soreness developed (p < 0.05) immediately (37 ± 25 mm) and 48 h (45 ± 26 mm) post-DR. IPT and rate of torque development (RTD) at late phases (> 150 ms) from the onset of muscle contraction decreased significantly (− 10.7 ± 6.1% and from − 15.4 to − 18.7%, respectively) immediately after LR for the CON group and remained below baseline values (− 5.6 ± 8.5% and from − 13.8 to − 14.9%, respectively) 48 h post-LR. However, IPT and late RTD were not significantly affected by LR for the EXP group, showing a group x time interaction effect. We concluded that a single DR bout can be used to attenuate fatigue induced by a LR performed fourteen days after.

Downhill Running: An Effective Countermeasure To Limitations Of Exercise In Acute Hypoxia?

Exercise stress that results in increased expression of heat shock protein 72 (Hsp72) is linked to physiologic adaptations. Adaptations to one environmental stressor, such as heat, increase Hsp72 and induce cross adaptations to other stressors (i.e. hypoxia). Previously, two bouts of downhill running (DHR) conferred classic markers of heat acclimation (lower Tc, earlier onset of sweating). We sought to increase Hsp72 through repeated DHR to potentially expedite the acclimation process. PURPOSE: To analyze the effect of DHR on exercise performance in normobaric hypoxia. METHODS: 8 males (23.8 ± 5.8 years, VO2max 54.1 ± 5.1 ml kg-1 min-1, 13.6 ± 5.2% body fat) performed two 45-minute DHR bouts (-12.5% grade) separated by 5-7 days in the speed that elicited VT while running downhill. Pre and post blood samples were collected to quantify monocyte Hsp72. Muscle soreness (DOMS) was assessed 24 and 48 hours after each downhill bout using a Likert scale. Two normobaric hypoxic (16% FiO2) 5 km time trials (TT) were performed: one before any DHR and one 5-7 days after the last bout. Hydration was assessed before the TT while blood lactate was measured pre and post TT. During the TT, heart rate, RPE and O2 saturation (SaO2) were recorded every 1 km. RESULTS: Monocyte Hsp72 showed no change across time (p=0.53). Specifically, basal concentration from DHR I to DHR II were not different (3.5 ± 2.3 to 2.9 ± 1.5 AU). TT performance was similar between conditions (1377 ± 192 ; 1364 ± 174 sec). Hydration (1.018 ± 0.007; 1.013 ± 0.009 urine specific gravity), RPE (14.9 ± 1.1; 14.6 ± 1.3), HR (178 ± 8;178 ± 8), and blood lactate (post TT1 11.6 ± 1.8; post TT2 12.0 ± 3.1 mM) were similar in both TTs. However, SaO2 significantly increased from TT1 to TT2 (84.5 ± 4.0; 87.2 ± 2.3%, p<0.05). DOMS was significantly lowered 24 (5.1 ± 0.8 to 3.5 ± 1.4, p = 0.00) and 48 (4.6 ± 1.0 to 2.6 ± 1.5, p = 0.00) hours following the second DHR trial when compared to the first trial. CONCLUSIONS: While no change in Hsp72 or TT time were observed, this could be due to large variations found in the data with these variables. The increase in SaO2 after DHR may improve exercise capacity at elevation during moderate exercise intensities.

Water intake after dehydration makes muscles more susceptible to cramp but electrolytes reverse that effect

ObjectiveNo previous study has compared water and oral rehydration solution (ORS) intake after dehydration induced by exercise in the heat for the effect on muscle cramps. The present study tested...

Adaptive Stress Response to Repeated Bouts of Downhill Running

Adaptive Stress Response to Repeated Bouts of Downhill Running

Repeated Bouts Of Downhill Running Prevent Intense Eccentric Exercise-induced Muscle Damage In Type II Diabetes Rats

Repeated Bouts Of Downhill Running Prevent Intense Eccentric Exercise-induced Muscle Damage In Type II Diabetes Rats

GSK3β inhibition and LEF1 upregulation in skeletal muscle following a bout of downhill running

Canonical Wnt signaling is important in skeletal muscle repair but has not been well characterized in response to physiological stimuli. The objective of this study was to assess the effect of downhill running (DHR) on components of Wnt signaling. Young, male C57BL/J6 mice were exposed to DHR. Muscle injury and repair (MCadherin) were measured in soleus. Gene and protein expression of Wnt3a, active β-catenin, GSK3β, and LEF1 were measured in gastrocnemius. Muscle injury increased 6days post-DHR and MCadherin protein increased 5days post-DHR. Total and active GSK3β protein decreased 3days (9-fold and 3.6-fold, respectively) post-DHR. LEF1 protein increased 6days (5-fold) post-DHR. DHR decreased GSK3β and increased LEF1 protein expression, but did not affect other components of Wnt signaling. Due to their applicability, using models of physiological stimuli such as DHR will provide significant insight into cellular mechanisms within muscle.

Acute heat stress prior to downhill running may enhance skeletal muscle remodeling

Heat shock proteins (HSPs) are chaperones that are known to have important roles in facilitating protein synthesis, protein assembly and cellular protection. While HSPs are known to be induced by damaging exercise, little is known about how HSPs actually mediate skeletal muscle adaption to exercise. The purpose of this study was to determine the effects of a heat shock pretreatment and the ensuing increase in HSP expression on early remodeling and signaling (2 and 48h) events of the soleus (Sol) muscle following a bout of downhill running. Male Wistar rats (10weeks old) were randomly assigned to control, eccentric exercise (EE; downhill running) or heat shock + eccentric exercise (HS; 41°C for 20 min, 48 h prior to exercise) groups. Markers of muscle damage, muscle regeneration and intracellular signaling were assessed. The phosphorylation (p) of HSP25, Akt, p70s6k, ERK1/2 and JNK proteins was also performed. As expected, following exercise the EE group had increased creatine kinase (CK; 2h) and mononuclear cell infiltration (48h) compared to controls. The EE group had an increase in p-HSP25, but there was no change in HSP72 expression, total protein concentration, or neonatal MHC content. Additionally, the EE group had increased p-p70s6k, p-ERK1/2, and p-JNK (2h) compared to controls; however no changes in p-Akt were seen. In contrast, the HS group had reduced CK (2h) and mononuclear cell infiltration (48h) compared to EE. Moreover, the HS group had increased HSP72 content (2 and 48h), total protein concentration (48h), neonatal MHC content (2 and 48h), p-HSP25 and p-p70s6k (2h). Lastly, the HS group had reduced p-Akt (48h) and p-ERK1/2 (2h). These data suggest that heat shock pretreatment and/or the ensuing HSP72 response may protect against muscle damage, and enhance increases in total protein and neonatal MHC content following exercise. These changes appear to be independent of Akt and MAPK signaling pathways.

MCP‐1 −/− Mice Show Blunted Inflammatory Cytokine Response and Improved Recovery Following Exercise‐Induced Muscle Damage

The body's inflammatory response to eccentric‐biased exercise in both brain and muscle contributes to impaired performance recovery. Monocyte chemoattractant protein (MCP‐1) is essential in the release of inflammatory mediators, but its role in exercise‐induced muscle damage has not yet been determined. The purpose of this study was to determine the role of MCP‐1 on brain and muscle inflammation following a novel bout of downhill running. C57BL/6 (n=24) and MCP‐1−/− mice (n=24), 8 weeks of age were randomly assigned to one of six groups: downhill runner wild type (DH‐WT), uphill runner wild type (UH‐WT), sedentary wild type (WT), downhill runner MCP‐1−/− (DH‐MCP‐1−/−), uphill runner MCP‐1−/− (UH‐MCP‐1−/−), and sedentary MCP‐1−/− (MCP‐1−/−). The mice were run on a treadmill at −/+14% grade and 22m/min, for 150 min. Mice were sacrificed at 24h post downhill run, and the brain and gastrocnemius muscle (G) were dissected and analyzed for IL‐1β, IL‐6, TNF‐α and F4/80 mRNA using RT‐PCR. Gene expression of IL‐1β, IL‐6 and TNF‐α was increased in the cerebellum, cortex and G in DH‐WT relative to WT (p&lt;0.05), whereas DH‐MCP‐1−/− was not different from WT. A similar effect was observed for F4/80 but this reached statistical significance in G only (p&lt;0.05). No differences were found in any other groups. These data support a necessary role for MCP‐1 following exercise‐induced muscle damage.Supported by a grant from NASA and ACSM.

Adaptation of Insulin-Resistance Indicators to a Repeated Bout of Eccentric Exercise in Human Skeletal Muscle

This study determined whether disrupted glucose and insulin responses to an oral glucose-tolerance test (OGTT) induced by eccentric exercise were attenuated after a repeated bout. Female participants (n = 10, age 24.7 +/- 3.0 yr, body mass 64.9 +/- 7.4 kg, height 1.67 +/- 0.02 m, body fat 29% +/- 2%) performed 2 bouts of downhill running (DTR 1 and DTR 2) separated by 14 d. OGTTs were administered at baseline and 48 hr after DTR 1 and DTR 2. Maximum voluntary isometric quadriceps torque (MVC), subjective soreness (100-mm visual analog scale), and serum creatine kinase (CK) were assessed pre-, post-, and 48 hr post-DTR 1 and DTR 2. Insulin and glucose area under the curve (38% +/- 8% and 21% +/- 5% increase, respectively) and peak insulin (44.1 +/- 5.1 vs. 31.6 +/- 4.0 muU/ml) and glucose (6.5 +/- 0.4 vs. 5.5 +/- 0.4 mmol/L) were elevated after DTR 1, with no increase above baseline 48 hr after DTR 2. MVC remained reduced by 9% +/- 3% 48 hr after DTR 1, recovering back to baseline 48 hr after DTR 2. Soreness was elevated to a greater degree 48 hr after DTR 1 (48 +/- 6 vs. 13 +/- 3 mm), with a tendency for greater CK responses 48 hr after DTR 1 (813 +/- 365 vs. 163 +/- 43 U/L, p = .08). A novel bout of eccentric exercise confers protective effects, with subsequent bouts failing to elicit disruptions in glucose and insulin homeostasis.

Effects of eccentric treadmill exercise on inflammatory gene expression in human skeletal muscle

The present study examined the skeletal muscle expression of several genes related to the inflammatory process before and after a bout of downhill running. Twenty-nine males between the ages of 18 and 35 years performed a 45-min downhill (-17.5%) treadmill protocol at 60% of maximal oxygen consumption. Venous bloods samples and muscle biopsy samples from the vastus lateralis were donated prior to and at 3-h and 24-h postexercise, along with ratings of perceived muscle soreness. Serum creatine kinase (CK) was determined, as was skeletal muscle gene expression of interleukin (IL)-6, IL-8, IL-12 (p35), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, cyclooxygenase 2 (COX2), and nuclear factor kappa B (NFkB) (p105/p50). Gene expression was analyzed using RT-PCR and compared with a standard housekeeping gene (beta-actin). Data were analyzed for statistical differences using multivariate analysis of variance with univariate follow-up. In addition, Pearson correlations were conducted to determine if any significant relationship exists between any of these transcripts and both CK and muscle soreness. Significant (p < 0.05) up-regulations in IL-6, IL-8, and COX2 mRNA expression were observed compared with baseline, whereas no significant changes for IL-12, IL-1beta, TNF-alpha, or NFkB were noted. Significant increases in IL-6 mRNA were observed at 3 h (p < 0.001) and 24 h (p = 0.043), whereas significant increases in IL-8 (p = 0.001) and COX2 (p = 0.046) mRNA were observed at 3-h postexercise. In addition, muscle soreness was significantly correlated with IL-8 at 24 h (r = -0.370; p = 0.048), whereas CK was significantly related to NFkB at baseline (r = -0.460; p = 0.012). These data indicate that increases in the mRNA expression of IL-6, IL-8, and COX2 occur in the vastus lateralis as a result of damaging eccentric exercise in young, recreationally trained males. Further, it appears that IL-8 transcription may play some role in inhibiting postexercise muscle soreness, possibly through regulation of angiogenesis.

Changes in neutrophil count, creatine kinases and muscle soreness after repeated bouts of downhill running

Objective. A primary objective was to examine circulating neutrophil count after repeated bouts of downhill running. An additional aim was to determine creatine kinase (CK) levels during the initial 12 hours, after repeated DHRs. Design. Eleven healthy, untrained Caucasian males performed 2 x 60 min bouts of DHR (-13.5%), spaced 14 days apart, at a speed equal to 75% VO2max on a level grade. Blood was collected before, after, and every hour for 12 hours, and every 24 hours for 6 days. Absolute neutrophil count, CK, and delayed-onset muscle soreness (DOMS) were assessed. Results were analysed using repeated measures ANOVA (p

Gender and exercise regulate HSP25, HSP70 and HSC70 expression following six bouts of downhill running in murine skeletal muscle

Gender and exercise regulate HSP25, HSP70 and HSC70 expression following six bouts of downhill running in murine skeletal muscle

Gender and exercise regulate MAPKs following 1, 2 and 6 bouts of downhill running in murine skeletal muscle

MAPKs (ERK1, ERK2, p38 and JNK) are part of the cellular stress response following exercise. Male and female mice (n=5) ran downhill (−15°) for 15 min for one, two or six bouts of exercise. The two bouts were separated by a week and the six bouts were completed every other day for three days followed by a two day rest. Following all three exercises, the MAPK activities showed striking gender and bout specific responses. The magnitude of these responses decreased with the number of bouts completed, likely due either to the repeated bout phenomenon or to the initiation of a hypertrophic program in the 2 and 6 bout protocols. Overall in all three exercise protocols, ERK1 and ERK2 activities showed a much more robust response to exercise than the SAPK’s, p38 and JNK, activities. Additionally, the females showed a greater magnitude response than did the males. Following six bouts of exercise, the myogenic markers cyclinD1 and PCNA, as well as citrate synthase, were markedly increased in expression or activity, suggesting satellite cell proliferation. The number of bouts demonstrated a clear, gender-specific remodelling of the MAPK activities, as well as a differentiation between the MAPKs and SAPKs.

Changes in Running Economy following the Repeated Bout of Downhill Running

Changes in Running Economy following the Repeated Bout of Downhill Running

Gender Specific MAPK Responses in Murine Skeletal Muscle Following Six Bouts of Exercise

MAPKs (ERK1/2, p38, JNK) participate in the cellular response to exercise. This study analyzed the gender specific role of MAPKs in murine biceps brachii after six bouts of eccentrically-biased downhill running. The MAPK response seen in both genders is lower in overall magnitude than the response following a single bout of the same exercise. Exercise-naive female and male mice (8–10 weeks old, n=5) ran six downhill (15°, 20 m/min) bouts. Muscles were analyzed for MAPK activity in a pre-exercise (PE) control (−1 hr) and at 9 timepoints post-exercise (PX). ERK1 in males and females showed a similar, but opposite response (1–2 fold change from PE levels); males increased activity from 0–12 hr PX and females decreased activity between 12 and 168 hr PX. ERK2 activity decreased in females for the entire time course (0 to 672 hr) after the 6 bouts, reaching minimum levels at 9 fold below PE at 3 hr PX, whereas males generally increased ERK2 activity through 24 hr PX. p38 activity in males was elevated through 168 hr PX, whereas females also exhibited a significant decrease in p38 activity (2 fold below PE) from12 to 672 hr PX. JNK activity increased in females following exercise from 0 to 24 hr PX with a peak in activity at 3 hr PX (3 fold above PE), then decreased to 3 fold below PE from 72 to 168 hr PX. In males, JNK activity increased following exercise (peaked at 6 hr PX 6 fold above PE), with a significant decrease in activity occurring at 48 hr PX (4 fold below PE). These results demonstrate that gender is a strong determinant in ERK1, ERK2 and p38; males significantly increase these activities, whereas females decrease them following 6 bouts of downhill running.

Changes In Running Economy Following A Single Bout Of Downhill Running

Changes In Running Economy Following A Single Bout Of Downhill Running

Changes In Running Economy Following A Single Bout Of Downhill Running

Changes In Running Economy Following A Single Bout Of Downhill Running

INCREASED BODY FAT TO LEAN MASS RATIO RESULTS IN LARGER DECREMENTS IN QUADRICEPS STRENGTH FOLLOWING DOWNHILL RUNNING

1888 The purpose of this study was to determine if the added mechanical load of bearing body fat would result in greater muscle damage and decrements in leg strength following downhill running. The relationship between percentage body fat and strength decline caused by a bout of downhill running was investigated in 26 male runners (23.4±0.7 yr). Quadriceps strength was measured isokinetically one hour before and 48 hours after 30 minutes of downhill running (−11% grade). Quadriceps strength was reduced 3.8±0.5% after downhill running. Body fat was 13.4±2.1%, and was negatively correlated with the change in strength due to downhill running (r= −0.64, P<0.001). There was no relationship between body mass and the decrement in strength following downhill running. These data indicate that an increased ratio of fat mass to muscle mass places an increased load on the muscle during downhill running, possibly resulting in increased muscle damage. The ratio of fat mass to muscle mass is therefore a determinant (accounting for nearly 40% for the reduction in strength) of losses in muscle strength following downhill running. It can be concluded that individuals with increased body fat mass relative to muscle mass are at greater risk of developing muscle weakness, and potential muscle injury, following eccentric weight-bearing activities. Supported by a Grant from Experimental and Applied Sciences

Effects of ibuprofen on exercise-induced muscle soreness and indices of muscle damage.

Thirty-two volunteers participated in a two-period crossover study in which ibuprofen was tested against an identical placebo for its effectiveness in reducing muscle soreness and damage after two bouts of downhill running. Subjective soreness, quadriceps isometric strength and isometric endurance time at 50 percent of maximum strength, serum activities of creatine kinase, lactate dehydrogenase and aspartate transaminase and serum levels of creatinine and urea were recorded at intervals up to 72 hours after exercise. Each downhill run produced muscle soreness, and a decline in muscle strength and 50 percent endurance time, although these parameters were unaffected by ibuprofen treatment. All serum parameters measured increased after both runs, but for the three enzymes this increase was smaller after the second run. Serum creatine kinase and urea levels were higher in the ibuprofen group after both runs. These results indicate that ibuprofen is not an appropriate treatment for delayed onset muscle soreness and damage.