Acute Bout Of Resistance Exercise Research Articles

The Response of Leukemia Inhibitory Factor to High-Intensity and High-Volume Resistance Training in Trained Men

PURPOSE: Leukemia inhibitory factor (LIF) and Follistatin like-1 (FSTL1) are myokines involved in the inflammatory response, and have been suggested to be involved in muscle adaptation. The purpose of this study was to characterize the LIF and FSTL1 response to a high intensity (HI) and high volume (HV) bout of resistance exercise (RE) before (PRE) and after (POST) 7 weeks of HI and HV resistance training (RT). METHODS: Twenty resistance trained men (23.5±2.6 y, 1.79±0.05 m, 75.7±13.75) volunteered for this study. Following a 2-week preparatory phase, participants were randomized into either a HV (n = 10, 4 x 10-12RM, 1-min rest) or HI (n = 10, 4 x 3-5RM, 3-min rest) training protocol for 7 weeks (4 d·week-1). Blood draws were obtained prior to (BL), immediately (IP), 30 min (30P), and 60 min (60P) post-exercise at PRE and POST. Plasma LIF and FSTL1 concentrations were determined using a multiplex signaling assay kit and analyzed with MAGPIX® technology. Area under the curve (AUC) for each myokine was calculated via the trapezoidal method. Data were analyzed using a repeated measures ANOVA. When appropriate, post-hoc analysis using unpaired t-tests were conducted with Bonferroni corrections. In addition, bivariate relationships were examined using Pearson product-moment correlations. RESULTS: A significant (p=0.021) training x time interaction was observed for LIF. No main effect of time (p=0.262) was observed at PRE, but was at POST (p=0.025). LIF concentrations at 60P (13.29 pg[BULLET OPERATOR]mL-1) trended (p=0.083) towards an attenuation from BL concentrations (32.67 pg[BULLET OPERATOR]mL-1). A significant main effect of time was also observed for FSTL1. FSTL1 concentrations at 60P (6693 pg[BULLET OPERATOR]mL-1) were significantly (p=0.013) lower compared to IP (7542 pg[BULLET OPERATOR]mL-1) when collapsed across PRE and POST. Significant correlations were noted between ΔBLLIF and ΔBLFSTL1(r=0.834, p=0.01), and between ΔAUCLIF and ΔAUCFSTL1 (r=0.809, p=0.01). CONCLUSIONS: LIF concentrations were attenuated at 60P in response to an acute bout of RE after 7-weeks of training. Similarly, FSTL1 concentrations, collapsed across groups, were attenuated after exercise. Changes in LIF were highly correlated to changes in FSTL1 suggesting that adaptations regulating these myokines may be linked.

Resistance Exercise and Polyphenol Supplementation elicits Unique Recruitment of Monocyte Subsets in Untrained Men

PURPOSE: To examine the monocyte subset response to resistance exercise and supplementation with an aqueous proprietary polyphenol blend (PPB) sourced from Camellia sinensis. METHODS: Untrained men (n=38, 22.1 ± 3.1 yrs; 174.0 ± 7.9 cm; 77.8 ± 14.5 kg) were randomized to: PPB (n=13), placebo (PL; n=15) or control (CON; n=10). PPB and PL supplemented for 28 days prior to an acute bout of resistance exercise, consisting of 10 repetitions at 70% of 1-RM for the squat (6 sets), leg press (4 sets) and leg extension (4 sets). Blood was drawn pre (PR), immediately (IP), 1 (1H), 5 (5H), 24 (24H) and 48 (48H) hours post exercise (PPB/PL), or rest (CON). Biopsies were obtained from the vastus lateralis at PR, 1H, 5H and 48H. Plasma and intramuscular monocyte chemoattractant protein-1 (MCP-1) was assessed by multiplex assay. Relative percent of classical (CLAS; CD14++/CD16-), intermediate (INT; CD14++/CD16+) and nonclassical (NC; CD14+/CD16+) monocytes were assessed via flow cytometry. Repeated measures ANOVA were applied, and non-normally distributed data were LN transformed. RESULTS: A group x time interaction was observed for circulating MCP-1 (p = 0.005), which was greater at 5H in PPB (502.0 ± 154.2 pg[BULLET OPERATOR]ml-1; p = 0.001) and PL (416.8 ± 109.9 pg[BULLET OPERATOR]ml-1; p = 0.012) than CON (307.3 ± 142.6 pg[BULLET OPERATOR]ml-1). A time effect was observed for intramuscular MCP-1 content (p < 0.001), with elevations observed (PR: 9.6 ± 5.0 pg[BULLET OPERATOR]mg-1; p < 0.001) at 1H (374.2 ± 388.8 pg[BULLET OPERATOR]ml-1), 5H (595.7 ± 528.6 pg[BULLET OPERATOR]ml-1) and 48H (217.0 ± 189.1 pg[BULLET OPERATOR]ml-1). Interactions were observed for CLAS, INT and NC (p < 0.001) populations. At IP, CLAS was reduced in PPB (86.2 ± 7.6%; p = 0.008) and PL (85.9 ± 5.1%; p = 0.003) versus CON (93.8 ± 4.3%). At 1H, PPB (96.3 ± 2.0%; p = 0.002) and PL (95.3 ± 4.0%; p = 0.006) was greater than CON (90.8 ± 4.3%). INT were greater at IP in PPB (4.9 ± 2.3%; p = 0.034) and PL (6.0 ± 2.0; p = 0.001) than CON (2.9 ± 1.8%) and reduced at 1H in PPB (1.6 ± 1.0%; p = 0.003) and PL (2.0 ± 1.2%; p = 0.008) versus CON (3.4 ± 1.6%). PPB was greater than CON at 24H (6.7 ± 2.9%; 4.0 ± 0.9%; p = 0.016) and 48H (7.9 ± 3.4%; 4.1 ± 1.6%; p = 0.007). NC was greater at IP in PPB (8.9 ± 6.9%; p = 0.020) and PL (8.1 ± 4.0%; p = 0.028) than CON (3.4 ± 3.2%). CONCLUSIONS: Exercise resulted in increased MCP-1 and the mobilization of specific monocyte subsets. Supplementation with PPB may augment the monocyte response. Funded by Kemin Foods, L.C.

Endocrinological Roles for Testosterone in Resistance Exercise Responses and Adaptations.

Chronic increases in testosterone levels can significantly increase hypertrophy and strength, as has been demonstrated by pharmacological intervention. However, decreases in basal testosterone levels can have the opposite result, as has been seen in hypogonadal populations. Because of these profound effects on hypertrophy and strength, testosterone has often been studied in conjunction with resistance exercise to examine whether the endocrine system plays a role in adaptations to the stimulus. Whereas some studies have demonstrated a chronic increase in basal testosterone, others have failed to find an adaptation to regular resistance exercise. However, improvements in strength and hypertrophy appear to be possible regardless of the presence of this adaptation. Testosterone has also been shown to acutely rise immediately following an acute resistance exercise bout. While this substantial mobilization of testosterone is brief, its effects are seen for several hours through the upregulation of the androgen receptor. The role of this acute response at present is unknown, but further study of the non-genomic action and possible intracrinological processes is warranted. This response does not seem to be necessary for resistance training adaptations to occur either, but whether this response optimizes such adaptations has not yet been determined.

Sex-based difference in Achilles peritendinous levels of matrix metalloproteinases and growth factors after acute resistance exercise.

Several recent investigations have demonstrated that the ability of various tendons to alter structural and functional properties in response to exercise are muted in women compared with men. We hypothesize that this disparity between men and women may be due to a reduced tendon production of key mediators of tendon extracellular matrix (ECM) remodeling in response to mechanical loading, e.g., exercise. Using microdialysis before and after an acute bout of resistance exercise, we evaluated Achilles peritendinous levels of insulin-like growth factor-1 (IGF-1) and interleukin-6 (IL-6), which have both been shown to increase tendon collagen synthesis. Additionally, the matrix remodeling enzymes matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) were also evaluated. IGF-1 levels were elevated (P < 0.05) to a similar extent in men and women after 3 h of exercise but remained elevated at 4 h in only women. IL-6 levels were ~4-fold greater after exercise in both men and women (P < 0.05). MMP-2 levels increased to a similar extent (~2-3-fold) in men and women (P < 0.05). In contrast, MMP-9 increased with exercise but only in men (P < 0.05). Last, TIMP-1 levels also increased (P < 0.05) with exercise in men and women but the increase was more prolonged in women. In conclusion, we observed modest sex differences in tendon release of MMP-9, TIMP-1, and IGF-1 after acute resistance exercise. If such differences persist throughout a chronic exercise training, they may contribute to the reduced ability of women to adapt to exercise compared with men.NEW & NOTEWORTHY In this investigation we utilized microdialysis of the peritendinous Achilles to evaluate potential differences between men and women in tendon production of key regulators of extracellular matrix remodeling. We demonstrate that a modest sex-specific difference exists in peritendinous levels of several key extracellular matrix modulators after an acute bout of resistance exercise.

Striated muscle activator of Rho signalling (STARS) is reduced in ageing human skeletal muscle and targeted by miR-628-5p.

The striated muscle activator of Rho signalling (STARS) is a muscle-specific actin-binding protein. The STARS signalling pathway is activated by resistance exercise and is anticipated to play a role in signal mechanotransduction. Animal studies have reported a negative regulation of STARS signalling with age, but such regulation has not been investigated in humans. Ten young (18-30years) and 10 older (60-75years) subjects completed an acute bout of resistance exercise. Gene and protein expression of members of the STARS signalling pathway and miRNA expression of a subset of miRNAs, predicted or known to target members of STARS signalling pathway, were measured in muscle biopsies collected pre-exercise and 2h post-exercise. For the first time, we report a significant downregulation of the STARS protein in older subjects. However, there was no effect of age on the magnitude of STARS activation in response to an acute bout of exercise. Finally, we established that miR-628-5p, a miRNA regulated by age and exercise, binds to the STARS 3'UTR to directly downregulate its transcription. This study describes for the first time the resistance exercise-induced regulation of STARS signalling in skeletal muscle from older humans and identifies a new miRNA involved in the transcriptional control of STARS.

The effect of an acute bout of resistance exercise on carotid artery strain and strain rate.

Arterial wall mechanics likely play an integral role in arterial responses to acute physiological stress. Therefore, this study aimed to determine the impact of low and moderate intensity double‐leg press exercise on common carotid artery (CCA) wall mechanics using 2D vascular strain imaging. Short‐axis CCA ultrasound images were collected in 15 healthy men (age: 21 ± 3 years; stature: 176.5 ± 6.2 cm; body mass; 80.6 ± 15.3 kg) before, during, and immediately after short‐duration isometric double‐leg press exercise at 30% and 60% of participants' one‐repetition maximum (1RM: 317 ± 72 kg). Images were analyzed for peak circumferential strain (PCS), peak systolic and diastolic strain rate (S‐SR and D‐SR), and arterial diameter. Heart rate (HR), systolic and diastolic blood pressure (SBP and DBP) were simultaneously assessed and arterial stiffness indices were calculated post hoc. A two‐way repeated measures ANOVA revealed that during isometric contraction, PCS and S‐SR decreased significantly (P < 0.01) before increasing significantly above resting levels post exercise (P < 0.05 and P < 0.01, respectively). Conversely, D‐SR was unaltered throughout the protocol (P = 0.25). No significant differences were observed between the 30% and 60% 1RM trials. Multiple regression analysis highlighted that HR, BP, and arterial diameter did not fully explain the total variance in PCS, S‐SR, and D‐SR. Acute double‐leg press exercise is therefore associated with similar transient changes in CCA wall mechanics at low and moderate intensities. CCA wall mechanics likely provide additional insight into localized intrinsic vascular wall properties beyond current measures of arterial stiffness.

Dose-Response and Time Course Effects of Acute Resistance Exercise on Executive Function.

The purpose of this study was to examine possible dose-response and time course effects of an acute bout of resistance exercise on the core executive functions of inhibition, working memory, and cognitive flexibility. Twenty-eight participants (14 female; Mage = 20.5 ± 2.1 years) completed a control condition and resistance exercise bouts performed at 40%, 70%, and 100% of their individual 10-repetition maximum. An executive function test battery was administered at 15 min and 180 min postexercise to assess immediate and delayed effects of exercise on executive functioning. At 15 min postexercise, high-intensity exercise resulted in less interference and improved reaction time (RT) for the Stroop task, while at 180 min low- and moderate-intensity exercise resulted in improved performance on plus-minus and Simon tasks, respectively. These findings suggest a limited and task-specific influence of acute resistance exercise on executive function in healthy young adults.

Matrix metalloproteinases in exercise and obesity

Matrix metalloproteinases (MMPs) are zinc- and calcium-dependent endoproteinases that have the ability to break down extracellular matrix. The large range of MMPs’ functions widens their spectrum of potential role as activators or inhibitors in tissue remodeling, cardiovascular diseases, and obesity. In particular, MMP-1, -2, and -9 may be associated with exercise and obesity. Thus, the current study reviewed the effects of different types of exercise (resistance and aerobic) on MMP-1, -2, and -9. Previous studies report that the response of MMP-2 and -9 to resistance exercise is dependent upon the length of exercise training, since long-term resistance exercise training increased both MMP-2 and -9, whereas acute bout of resistance exercise decreased these MMPs. Aerobic exercise produces an inconsistent result on MMPs, although some studies showed a decrease in MMP-1. Obesity is related to a relatively lower level of MMP-9, indicating that an exercise-induced increase in MMP-9 may positively influence obesity. A comprehensive understanding of the relationship between exercise, obesity, and MMPs does not exist yet. Future studies examining the acute and chronic responses of these MMPs using different subject models may provide a better understanding of the molecular mechanisms that are associated with exercise, obesity, and cardiovascular disease.

Vascular Responses Following an Acute Bout of Resistance Exercise in Resistance-trained Individuals

Evaluation of arterial stiffness and pulse wave reflection provide insight into vascular function to a greater degree than traditional measures such as blood pressure (BP). PURPOSE: To determine the effects of an acute bout of free-weight resistance exercise on arterial stiffness, peripheral and central BP, and pulse wave reflection in young, resistance trained individuals. METHODS: Fifteen young, healthy individuals (aged 23±3 yrs) with 9±3 yrs of resistance training volunteered for the study. Participants performed 2 counterbalanced sessions consisting of an acute bout of resistance exercise (ARE) using free-weights or a quiet control. The ARE consisted of 3 sets of 10 repetitions at 75% 1 repetition maximum for the squat, bench press, and deadlift with 2 minutes of rest between sets and exercises. The quiet control consisted of the participant lying supine for 30 minutes. Data were collected at rest and 10 minutes during recovery for each session. Arterial stiffness was assessed using carotid-femoral pulse wave velocity (cfPWV) while pulse wave reflection was evaluated using applanation tonometry. A repeated measures ANOVA was used to determine the effects of condition (ARE, control) across time (rest, recovery). RESULTS: There was a significant interaction for cfPWV (rest: 5.34±0.61; recovery: 5.86±0.74, p≤0.05) such that it was elevated during recovery from the ARE, but not the control. There were no significant interactions (p>0.05) for peripheral or central BP. However, there were significant interactions for the augmentation index (AIx)(rest: 115.8±8.7; recovery: 123.2±8.5, p=0.004), the AIx normalized at 75bpm (rest: 3.3±14.9; recovery: 27.3±13.1, p=0.0001), augmentation pressure (rest: 4.5±5.7; recovery: 10.4±5.7mmHg, p=0.003), time of the reflected wave (rest: 150.3±7.1ms; recovery: 145.5±5.6ms, p=0.003), and wasted left ventricular energy (rest: 641.6±684.2dynes s/cm2; recovery: 1785.3±920.6dynes s/cm2, p=0.013) such that they were altered during recovery from the ARE but not the control. CONCLUSIONS: These data demonstrate that an acute bout of free-weight resistance exercise does not alter peripheral or central BP, but does significantly increase arterial stiffness and measures of pulse wave reflection.

Menstrual Phase and the Vascular Response to Acute Resistance Exercise In Women

Aerobic exercise has a favorable effect on arterial stiffness and reduces the risk for cardiovascular disease (CVD). The effects of resistance exercise (RE) on arterial stiffness are less clear. Acute RE increases central stiffness and decreases peripheral stiffness in men. However, cyclic hormonal changes in women may modulate the vascular response to RE. PURPOSE: To examine the effect of acute RE on central and peripheral arterial stiffness in women during the early follicular and ovulatory phase of the menstrual cycle. METHODS: Eighteen healthy women (28±7 years, Body Mass Index (BMI) 22.6±2.9 kg/m2) completed an acute RE bout during the early follicular and ovulatory phase of the menstrual cycle. Salivary 17β-Estradiol concentration was measured during each phase. Pulse-Wave Velocity (PWV) was obtained from the carotid-femoral and carotid-radial pulse sites to measure central and peripheral arterial stiffness, respectively. PWV was measured at rest, immediately, 10, 20 and 30 minutes post-RE. RESULTS: 17β-Estradiol concentration was significantly lower in the early follicular versus ovulatory phase (1.78±0.51 pg/ml vs. 2.40±0.26 pg/ml, p<0.05). Central PWV significantly increased (p<0.05) and peripheral PWV significantly decreased (p<0.05) post-RE in early follicular and ovulatory phase. No phase-by-time interaction was detected for either vascular segment (Table, p>0.05). CONCLUSION: Menstrual cycle phase may not influence the vascular response to acute RE, even though there are significant differences in 17β-Estradiol concentrations between menstrual phases. Supported by NIH NIA P30 AG0344645 05 (KSH).Table: No title available.a Significantly different from baseline (time effect), p<0.05; MAP, Mean Arterial Pressure.

Training Enhances the Recovery of Monocyte Subset Response to a Bout of Resistance Exercise

Monocytes play a key role in inflammatory processes. Little is known on monocyte response to resistance exercise. The purpose of this study was to examine the acute changes in monocyte subsets following an acute muscle damaging bout of resistance exercise before (PRE) and after (POST) six weeks of resistance training. Fifteen recreationally active men (22.1 ± 2.2 y) completed an acute, muscle damaging protocol PRE and POST that consisted of the squat (6 sets), leg press (4 sets) and leg extension (4 sets) exercises. Ten repetitions at 70% of 1‐RM were completed for each set. Blood was drawn at baseline (BL), immediately (IP), one (1H), five (5H), 24 (24H) and 48 hours (48H) post‐exercise. Flow cytometry was used to identify monocyte subpopulations: classical (CLAS; CD14++/CD16−) and intermediate (INT; CD14++/CD16+). Repeated measures ANOVA was applied. A significant training x time interaction was observed for CLAS (p = 0.008) and INT (p = 0.036). CLAS significantly increased at 1H (BL, 89.3±5.5% vs.1H, 95.10 ± 4.19%; p &lt; 0.001) and 5H (p = 0.012; 91.79 ± 4.14%) in PRE, while at POST, only a trend toward a significant increase was noted at 1H (BL, 90.66 ± 4.62% vs. 1H, 92.50 ± 3.75%, p = 0.067). Additionally, CLAS was significantly higher PRE than POST at 1H (95.10 ± 4.19% vs. 92.50± 3.75%; p = 0.048) and 5H (91.79 ± 4.14% vs. 88.42 ± 5.46%; p = 0.005). During PRE, the proportion of INT appeared to increase (p &lt; 0.001) from BL (4.23 ± 2.19%) at IP (5.62 ± 2.77%), but decreased at both 1H (p &lt; 0.001; 2.01 ± 1.56%) and 5H (p = 0.001; 3.16 ± 1.82%). However, increases from BL were noted at 24H (p = 0.010; 5.83 ± 3.35%) and 48H (p = 0.049; 6.15 ± 3.25%). At POST, changes in INT were similar to PRE, except proportion of INT returned to BL levels at 5H and remained there throughout the 48H recovery period. In conclusion, resistance training appears to enhance the recovery of monocyte subsets to resting proportions following an acute bout of resistance exercise.

Changes in the BDNF Response to Resistance Exercise is Associated with Changes in Power Performance in Experienced, Resistance‐Trained Men

Brain‐derived neurotrophic factor (BDNF) has been demonstrated to have an important role in neuronal remodeling and modulating synaptic plasticity and neurotransmitter release. Acute elevations in BDNF concentrations have been seen following resistance exercise (RE), however knowledge regarding the training response from different resistance training protocols is limited. Thus, the purpose of this study was to examine changes in circulating BDNF concentrations at rest and in response to exercise following 8‐weeks of resistance training in experienced, resistance trained men. Twenty resistance trained men were randomly assigned to either a high intensity (HI; n=10, 22.6±2.3 y; 87.0±15.1 kg; 1.79±0.05m) or high volume (HV; n=10, 24.5±2.6 y; 89.5±12.9 kg; 1.66±0.34m) training protocol. Power outputs were determined by a linear velocity transducer attached to the barbell during one repetition maximum (1RM) assessment of the bench press (BP) and squat (SQT) exercises. Prior to the 8‐week resistance training program (PRE), participants performed an acute bout of exercise using either the HI (3–5 reps; 90% 1‐RM) or HV (10–12 reps; 70% 1‐RM) training paradigm. The acute exercise protocol was repeated following the 8‐week training program (POST). Blood samples were obtained prior to (BL), immediately (IP), 30 min (30P) and 60 min (60P) post‐exercise at PRE and POST. Area under the curve with respect to increase (AUCi) was determined using the trapezoidal method and subtracting the distance from baseline at all measurements. Raw data were square root transformed due to non‐normality. Data was analyzed using a training x group repeated measures ANOVA, and bivariate relationships were examined using Pearson product‐moment correlations. No significant main effects for training (p=0.408) or significant (p=0.483) interactions were observed for AUCi. However, a significant main effect for group (p=0.044) was observed. Post hoc analysis demonstrated AUCi values were not significantly different between groups at PRE (p=0.339), but were at POST (p=0.032). No significant differences in circulating concentrations for resting BDNF or in the training response was noted following 8‐week training program for either HI or HV. However, significant correlations were noted between the change in BDNF AUCi and the change in peak power output during the BP exercise (r=0.594, p=0.006) and the change in relative peak power BP (r=0.600, p=0.005). The results of this study indicated that 8‐weeks of resistance training did not alter BL or the AUCi response of BDNF to an acute bout of resistance exercise in resistance trained men. However, an acute HV bout elicited significantly higher BDNF AUCi as compared to HI after 8 weeks of training but not before. In addition, changes in BDNF AUCi appear to be related to changes in power output during the BP exercise only.

Acute Effects of 30 Minutes Resistance and Aerobic Exercise on Cognition in a High School Sample

Purpose: The purpose of this study was to determine differences in cognition between acute bouts of resistance exercise, aerobic exercise, and a nonexercise control in an untrained youth sample. Method: Ninety-four participants performed 30 min of aerobic exercise, resistance exercise, or nonexercise separated by 7 days each in a randomized crossover design. After each exercise intervention, participants were assessed using 2 cognitive tests. The Dot, Word, and Color elements of the Stroop Test (Victoria version) and Parts A and B of the Trail-Making Test were used to measure cognition. Results: Acute resistance and aerobic exercise resulted in similar improvements over nonexercise in all forms of the Stroop Test. Acute aerobic exercise led to improved performance over nonexercise and resistance exercise in Part B of the Trail-Making Test. Neither exercise intervention showed significant changes in time to complete Part A of the Trail-Making Test. Boys outperformed girls on the Stroop Dot and Color Test following acute aerobic exercise, in the Stroop Dot, Word, and Color Test following acute resistance exercise, and in the Stroop Color Test and Trail-Making Test Part B following nonexercise. Conclusions: Both acute resistance and aerobic exercise increased measures of cognition over a nonexercise control in untrained high school youth. These findings suggest the merits of acute resistance exercise as an alternative or complement to aerobic activity for educators aiming to increase youth physical activity and cognitive function concurrently.

Oxidative DNA damage and lipid peroxidation to cluster vs. traditional sets resistance exercise in professional volleyball players

Cells continuously produce free radicals and reactive oxygen species (ROS) as part of metabolic processes. Exercise can induce an imbalance between ROS and antioxidants, which is referred to as oxidative stress. Acute bout of resistance exercise (RE) induces activation of several distinct systems of radicals generation, but the effects of different RE loading on oxidative stress response is not clear. Therefore, the purpose of this study was to examine the influence of cluster vs. traditional sets of RE on oxidative DNA damage, lipid peroxidation and uric acid response in athletes. To elicit blood oxidative stress, 12 professional young male volleyball players undertook two different RE loading patterns: 1) cluster loading pattern, 2) traditional loading pattern which was standardized for total volume and completed in a randomized crossover fashion with a four-day interval between trials. Blood samples were collected before and after RE for markers of oxidative stress and damage. In response to both the cluster and traditional sets, 8-hydroxy-2-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal (4-HNE), and uric acid were significantly elevated post exercise (p&amp;lt;.05). Although no statistically significant differences between loading patterns were observed, the rate of elevations in 8-OHdG (effect size [ES]: 1.4 vs. 1.3) and 4-HNE (ES: 8.1 vs. 7.9) was greater for the traditional sets; likewise, the rate of uric acid excretion was greater for the cluster RE (ES: 1.6 vs. 1.4). These data suggests that RE induced DNA damage, and lipid peroxidation, but they were greater for the traditional RE. Therefore, strength and conditioning professionals in the field of volleyball must keep in their mind that RE induces oxidative stress and should use proper RE loading patterns in their training schedule.

Corticomotor Excitability is Increased Following an Acute Bout of Blood Flow Restriction Resistance Exercise.

We used transcranial magnetic stimulation (TMS) to investigate whether an acute bout of resistance exercise with blood flow restriction (BFR) stimulated changes in corticomotor excitability (motor evoked potential, MEP) and short-interval intracortical inhibition (SICI), and compared the responses to two traditional resistance exercise methods. Ten males completed four unilateral elbow flexion exercise trials in a balanced, randomized crossover design: (1) heavy-load (HL: 80% one-repetition maximum [1-RM]); (2) light-load (LL; 20% 1-RM) and two other light-load trials with BFR applied; (3) continuously at 80% resting systolic blood pressure (BFR-C); or (4) intermittently at 130% resting systolic blood pressure (BFR-I). MEP amplitude and SICI were measured using TMS at baseline, and at four time-points over a 60 min post-exercise period. MEP amplitude increased rapidly (within 5 min post-exercise) for BFR-C and remained elevated for 60 min post-exercise compared with all other trials. MEP amplitudes increased for up to 20 and 40 min for LL and BFR-I, respectively. These findings provide evidence that BFR resistance exercise can modulate corticomotor excitability, possibly due to altered sensory feedback via group III and IV afferents. This response may be an acute indication of neuromuscular adaptations that underpin changes in muscle strength following a BFR resistance training programme.

Neurotrophic growth factor responses to lower body resistance training in older adults.

Resistance exercise is an efficacious stimulus for improving cognitive function in older adults, which may be mediated by the upregulation of blood-borne neurotrophic growth factors (NTFs) like brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1). However, the NTF response to resistance exercise and training in older adults is poorly understood. Therefore, the purpose of this study was to characterize the timing and magnitude of the NTF response following an acute bout of resistance exercise before and after 8 weeks of resistance training. Ten cognitively normal, older adults (ages 60-77 years, five men) were examined. The acute NTF response to resistance exercise was assessed via serum samples drawn at designated time points following exercise. This procedure was then repeated following 8 weeks of resistance training. BDNF increased immediately post-exercise (Δ9% pre-training, Δ11% post-training) then returned to resting levels while IGF-1 remained stable following resistance exercise before and after 8 weeks of resistance training. Basal levels of both NTFs were unaffected by the 8 week training period. We report a transient increase in serum BDNF following a bout of resistance exercise in older adults, which could have implications for the design of interventions seeking to maximize cognitive function in older adults.

Effects of age on arterial stiffness and central blood pressure after an acute bout of resistance exercise.

To investigate the influence of age on arterial stiffness and blood pressure after performing a resistance exercise bout. Recreationally active men were separated into young (YG, n = 12, 26.5 ± 3.3 years), middle (MG, n = 14, 49.4 ± 5.7 years), and old (OG, n = 10, 67.4 ± 6.3 years)-aged groups. In a randomized cross-over design, participants performed control and exercise conditions with at least 3 days separating conditions. The exercise condition consisted of leg press, chest press, knee flexion, lat pulldown and knee extension at ~65% one-repetition maximum for three sets of 10 repetitions. Brachial and central blood pressures, augmented pressure, augmentation index, central and peripheral pulse wave velocities were measured prior to each condition and starting at 5 min post-exercise. Brachial systolic blood pressure (SBP) significantly increased similarly after exercise for all age groups (YG, 8 ± 8 mmHg; MG, 5 ± 5 mmHg; OG, 5 ± 6 mmHg; p < 0.05). However, central SBP did not significantly increase for any age group after exercise. Augmentation index significantly increased after exercise only in the YG (11 ± 8%, p < 0.05). Central pulse wave velocity did not significantly increase in any age group after exercise when compared to the control condition. When performing a whole body moderate resistance exercise bout, acute changes in arterial stiffness and blood pressure appear to be minimally affected by age.

Ribosome biogenesis adaptation in resistance training-induced human skeletal muscle hypertrophy.

Resistance training (RT) has the capacity to increase skeletal muscle mass, which is due in part to transient increases in the rate of muscle protein synthesis during postexercise recovery. The role of ribosome biogenesis in supporting the increased muscle protein synthetic demands is not known. This study examined the effect of both a single acute bout of resistance exercise (RE) and a chronic RT program on the muscle ribosome biogenesis response. Fourteen healthy young men performed a single bout of RE both before and after 8 wk of chronic RT. Muscle cross-sectional area was increased by 6 ± 4.5% in response to 8 wk of RT. Acute RE-induced activation of the ERK and mTOR pathways were similar before and after RT, as assessed by phosphorylation of ERK, MNK1, p70S6K, and S6 ribosomal protein 1 h postexercise. Phosphorylation of TIF-IA was also similarly elevated following both RE sessions. Cyclin D1 protein levels, which appeared to be regulated at the translational rather than transcriptional level, were acutely increased after RE. UBF was the only protein found to be highly phosphorylated at rest after 8 wk of training. Also, muscle levels of the rRNAs, including the precursor 45S and the mature transcripts (28S, 18S, and 5.8S), were increased in response to RT. We propose that ribosome biogenesis is an important yet overlooked event in RE-induced muscle hypertrophy that warrants further investigation.

Forearm Blood Flow And Reactive Hyperemia In Response To An Acute Bout Of Resistance Exercise Using Free-weights.

An acute bout of resistance exercise has been suggested to have a negative effect on vascular function. Previous studies have utilized isolation exercises on resistance machines rather than whole-body resistance exercises using free weights. PURPOSE: To evaluate the effects of free-weight resistance exercises on forearm blood flow (FBF) in resistance-trained individuals. METHODS: Ten young, healthy individuals (8 males, 2 females; aged 23±3 yrs) with 9±3 yrs of lifting experience were assessed for height (1.75±0.51m), weight (81.6±10.2kg) and body fat percentage (15.6±7.9%). One repetition maximum (1RM) was assessed on the squat (144.1±32.2kg), bench press (108.6±32.6kg) and deadlift (159.6±39.9kg). Vasodilatory capacity was assessed by strain gauge plethysmography at rest and followed by 5 minutes of circulatory occlusion (220 mmHg) to induce reactive hyperemia before and 10 minutes after an acute bout of resistance exercise consisting of 3 sets of 10 repetitions at 75% 1RM on the squat, bench press and deadlift. Each participant also completed a quiet control session of the same duration. Two minutes of rest was given between sets and exercises. Area under the curve (AUC) was also utilized to determine differences in blood flow. Data were analyzed by an analysis of variance to examine the effects of condition by time. Tukey HSD was used as a post-hoc test if the interaction was deemed significant. The alpha level was set apriori at 0.05. RESULTS: Resting FBF (4.2±1.5 2ml//min/100ml) and peak blood flow (20.4±13.62 ml//min/100ml) were similar at rest between conditions. There was a significant interaction (p<0.05) for FBF after the free-weight resistance exercises (10.9±6.2 ml//min/100ml) as well as peak blood flow (32.7±23. 2 ml//min/100ml) such that it was different than during rest and recovery after the control (FBF: 3.9±1.6 ml//min/100ml; peak blood flow: 20.4±12.3 ml//min/100ml). Area under the curve for FBF-RH significantly (p<0.05) increased after the acute bout of free-weight resistance exercises by 128% and did not change after the control (5.6%). CONCLUSION: These data demonstrate that free-weight resistance exercises significantly alter microvascular endothelial function in young, healthy resistance-trained individuals.

Delayed Activation of Muscle Protein Synthesis following Resistance Exercise in Mice is mTORC1‐Dependent

The activation of the mechanistic target of rapamycin-complex-1 (mTORC1) is important for muscle hypertrophy following resistance exercise. However, our present understanding of the dynamics of anabolic signaling and muscle protein synthesis (MPS) following an acute bout of resistance exercise in mice is lacking. PURPOSE: To determine the time course of anabolic signaling and MPS in response to an acute bout of resistance exercise in mice. METHODS: Three month old C57BL/6 mice (n = 56) were anesthetized, the sciatic nerve exposed before the point of trifurcation, and all of the muscles of the right distal hindlimb were stimulated for 10 sets of 6 repetitions with 1 minute rest between sets. Both control and stimulated tibialis anterior (TA) muscles were collected 0, 0.75, 1.5, 3, 4.5, 6, 9, 12 and 24 hours post-loading. Thirty minutes prior to collection animals were injected with 100 μL of 0.04 μmol/g puromycin. Two additional groups of mice were injected with 110 μL of 1.5 μg/g rapamycin or saline immediately prior to loading and collected 6h later. Muscles were processed for western blot analysis of proposed anabolic signaling molecules and MPS via SUnSET. RESULTS: ERK1/2 phosphorylation peaked at 0.75h (2.76 ± 0.60) and pS6K1 Thr389 was significantly higher 1.5h (4.18 ± 2.75) and 3h (5.39 ± 0.62) post-loading (p < 0.05). MPS showed two peaks, the first at 0.75h (1.27 ± 0.14) and the second at 6h (1.27 ± 0.10) post-loading. Rapamycin abolished the peak at 6h even though mTORC1 activity was not elevated at this timepoint. CONCLUSION Following acute resistance exercise in mice, there are two peaks of anabolic activity. The first corresponds with an increase in ERK1/2 activity 0.75h after loading and the second, at 6h, is dependent on mTORC1 activation.