Single Session Of Resistance Training Research Articles

Modified-release gliclazide acutely improves recovery but causes undesirable blood glucose decrease after a resistance exercise session in healthy adults: a pilot study for a randomized clinical trial.

Sulfonylureas have been used to improve performance in strength sports. However, this hypothetical effect has not been proven. We examined the ergogenic acute effect of gliclazide on resistance training performance and muscle recovery. We conducted a double-blind, randomized, crossover pilot study with 10 healthy resistance-trained adults (29.3 ± 4.4 years), nonusers of anabolic steroids. The participants were randomized to two exercise sessions. In the first session, five participants received placebo and the other five received gliclazide modified release, both administered 8 hours before the session. Session two was performed in a crossover fashion a week later. The volume load was calculated as the maximum number of repetitions of four sets multiplied by load (65% 1-RM). Blood samples were collected before and after exercise, as well as 24 hours and 48 hours after exercise for measurement of creatine kinase (CK-MM) and lactate dehydrogenase (LDH) activity. Blood glucose was measured with a glucometer before, during, and after the exercise sessions. Gliclazide did not enhance volume load for bench press (placebo: 2,698.0 ± 923.0 kg; gliclazide: 2,675.0 ± 1,088.0 kg; p = 0.073) or leg press (placebo: 10,866.0 ± 2,671.0 kg; gliclazide: 10,817.0 ± 2,888.0 kg; p = 0.135). However, CK-MM (-27.7%; p = 0.034) and LDH (-21.1%; p = 0.021) activities were decreased with gliclazide 48 hours after exercise. There was also a decrease in blood glucose in the gliclazide compared with the placebo session (p = 0.018). Gliclazide did not enhance performance in a single resistance training session, but promoted faster muscle recovery. The decrease in blood glucose post-exercise with gliclazide was an undesirable effect that could lead to long-term glucose metabolism disorders. Registered in ClinicalTrials.gov under number NCT04443777.

Effects of 7-day quercetin intervention on motor unit activity and muscle contractile properties before and after resistance exercise in young adults randomized controlled trials.

We investigated whether the alteration of the motor unit recruitment threshold (MURT) caused by quercetin ingestion intervention for 7 days modifies motor unit activation patterns before and after a single session of resistance exercise. Twenty young male and female adults were divided into two groups: ingestion of placebo (PLA) or quercetin glycosides at 200mg/day (QUE). High-density surface electromyography during submaximal contractions was measured to assess the motor unit firing rate (MUFR) and MURT of the vastus lateralis muscle before (PRE) and after (POST) resistance exercise (DAY1). The same measurements were repeated after 7 days of placebo or quercetin glycoside ingestion (DAY8). In QUE, MURT decreased more from DAY1-PRE to DAY8-PRE (29.1±9.1 to 27.1±9.5% MVC, p<0.001) but not in PLA (29.8±10.4 to 28.9±9.7% MVC, p<0.167). For percentage change in MUFR following resistance exercise, there was a significant interaction (day × group, p<0.001). The degree of changes in MURT from DAY1-PRE to DAY8-PRE was significantly correlated with the percentage change of MUFR from DAY8-PRE to DAY8-POST in QUE (p=0.014, r = -0.363) but not in PLA (p=0.518). The study suggests that 7-day quercetin ingestion alters the motor unit recruitment pattern, and this may induce changes in motor unit firing patterns during a single session of resistance training (Trial registration: UMIN000052255, R000059650).

Effect of a resistance exercise at acute moderate altitude on muscle health biomarkers

The intensification of the stress response during resistance training (RT) under hypoxia conditions could trigger unwanted effects that compromise muscle health and, therefore, the ability of the muscle to adapt to longer training periods. We examined the effect of acute moderate terrestrial hypoxia on metabolic, inflammation, antioxidant capacity and muscle atrophy biomarkers after a single RT session in a young male population. Twenty healthy volunteers allocated to the normoxia (N < 700 m asl) or moderate altitude (HH = 2320 m asl) group participated in this study. Before and throughout the 30 min following the RT session (3 × 10 reps, 90 s rest, 70% 1RM), venous blood samples were taken and analysed for circulating calcium, inorganic phosphate, cytokines (IL-6, IL-10 and TNF-α), total antioxidant capacity (TAC) and myostatin. Main results displayed a marked metabolic stress response after the RT in both conditions. A large to very large proportional increase in the adjusted to pre-exercise change of inflammatory and anti-inflammatory markers favoured HH (serum TNF-α [ES = 1.10; p = 0.024] and IL-10 [ES = 1.31; p = 0.009]). The exercise produced a similar moderate increment of myostatin in both groups, followed by a moderate non-significant reduction in HH throughout the recovery (ES = − 0.72; p = 0.21). The RT slightly increased the antioxidant response regardless of the environmental condition. These results revealed no clear impact of RT under acute hypoxia on the metabolic, TAC and muscle atrophy biomarkers. However, a coordinated pro/anti-inflammatory response balances the potentiated effect of RT on systemic inflammation.

Altitude-induced effects on neuromuscular, metabolic and perceptual responses before, during and after a high-intensity resistance training session.

We tested if an acute ascending to 2320m above sea level (asl) affects corticospinal excitability (CSE) and intracortical inhibition (SICI) measured with transcranial magnetic stimulation (TMS) at rest, before, during and after a traditional hypertrophy-oriented resistance training (RT) session. We also explored whether blood lactate concentration (BLa), ratings of perceived exertion (RPE), perceived muscular pain and total training volume differed when the RT session was performed at hypoxia (H) or normoxia (N). Twelve resistance-trained men performed eight sets of 10 repetitions at 70% of one repetition maximum of a bar biceps curl at N (SpO2 = 98.0 ± 0.9%) and H (at 2320 asl, SpO2 = 94.0 ± 1.9%) in random order. Before each session, a subjective well-being questionnaire, the resting motor threshold (rMT) and a single pulse recruitment curve were measured. Before, during and after the RT session, BLa, RPE, muscle pain, CSE and SICI were measured. Before the RT session only the rMT differed between H (- 5.3%) and N (ES = 0.38). RPE, muscle pain and BLa increased through the RT session and were greater at H than N (12%, 54% and 15%, respectively) despite a similar training volume (1618 ± 468kg vs. 1638 ± 509kg). CSE was reduced during the RT session (~ 27%) but recovered ten minutes after, regardless of the environmental condition. SICI did not change after any RT session. The data suggest that acute exposure to moderate hypoxia slightly increased the excitability of the most excitable structures of the corticospinal tract but did not influence intracortical or corticospinal responses to a single RT session.

The acute effects of concurrent endurance and resistance training on circulating microRNAs in trained rugby players

MicroRNA (miR) are small noncoding RNA involved in the post-transcriptional regulation of gene expression and may serve as biomarkers of muscle fatigue and muscle adaptations. The present study aimed to explore the acute responses of cycling vs. running endurance exercises within a concurrent endurance/resistance training on some specific miR. We hypothesized miR would acutely reveal greater muscle damage during the running endurance exercise as compared to cycling that would affect muscle protein synthesis biomarkers.Twenty-five trained rugby players participated in three randomized experimental sessions: 1) cycling endurance training session followed by a resistance session (CYCLE), 2) running endurance training session followed by a resistance session (RUN), and 3) a single resistance training session (CONTROL). Cycling and running endurance sessions were conducted in the morning and consisted in three sets of six 6-s maximal (cycling or running) sprints with 24 seconds passive recovery. Four hours later, volunteers conducted the resistance training (afternoon) composed of several upper- and lower-body strength exercises with heavy loads and low repetitions. During CONTROL, volunteers only performed the resistance training during the afternoon. Blood samples were collected before (PRE), immediately after (POST) and 3h after (POST3) the resistance training sessions. Extracellular vesicular miR were subsequently extracted and quantified using a real time quantitative PCR.The statistical analyses revealed that hsa-miR-203a-3p, hsa-miR-205-5p and hsa-miR-184 were not affected by our experimental procedures (p&gt;0.05). hsa-miR-9-5p and hsa-miR-1290 were significantly higher during CONTROL as compared to CYCLE (p=.033 and p=.039, respectively). hsa-miR-206 was significantly higher POST during RUN as compared to CYCLE and CONTROL (p=.018 and p=.014, respectively). hsa-miR-19-3p was significantly higher during RUN as compared to CONTROL (p=.38).Taken as a whole, our results revealed some differences in circulating miR as a result of a running endurance exercise as compared to no endurance or cycling endurance exercise. Confirming our a priori hypothesis, the higher values of circulating miR suggested greater muscle damage (i.e., hsa-miR-206) after running that could affect the muscle protein synthesis pathway expected by a subsequent resistance training session. Indeed, the higher hsa-miR-19-3p after RUN could have an inhibitory effect on Akt/mTOR. It is therefore suggested that conducting cycling endurance exercises within a concurrent training program could lower the likely interferences between endurance and resistance training in trained individuals. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Potential mechanisms involved in regulating muscle protein turnover after acute exercise: A brief review.

It is well established that resistance training increases muscle mass. Indeed, there is evidence to suggest that a single session of resistance training is associated with an increase in muscle protein synthesis in young adults. However, the fundamental mechanisms that are involved in regulating muscle protein turnover rates after an acute bout of physical exercise are unclear. Therefore, this review will briefly focus on summarizing the potential mechanisms behind the growth of skeletal muscle after physical exercise. We also present mechanistic differences that may exist between young and older individuals during muscle protein synthesis and breakdown after physical exercise. Pathways leading to the activation of AKT/mTOR signals after resistance exercise and the activation of AMPK signaling pathway following a HIIT (High intensity interval training) are discussed.

Acute Response Of Blood Glucose After Two Resistance Training Protocols With Different Execution Velocities

PURPOSE: Studies have demonstrated that a single session of resistance training (RT) can reduce glycemia in subjects with or without diabetes. The aim of this study was to compare the acute response of blood glucose after 2 resistance training protocols with different execution velocities in amateur weightlifting athletes. METHODS: A randomized clinical trial was conducted in 24 amateur weightlifting athletes (23.5± 6.2 years). The participants were randomized into 2 groups: high velocity (MV, n =12) or low velocity (LV, n =12). The RT training protocol was based on a session with these characteristics: 3 sets of 12 repetitions at 60% of a maximum repetition in each of the exercises (bench press, squat and military press). The only difference between the training session was that the MV group performed all the repetitions at 100% of their maximum velocity and the LV group performed at 50%. This variable was controlled with the T-force system. An oral glucose tolerance test (OGTT) was conducted with metabolic measurements immediately after each RE protocol and every 30 min until 120 min of recovery. For the statistical analysis, the area under the blood glucose curve (AUC) was calculated at each time point. Cohen’s d for effect size were also calculated to determine the magnitude of the group differences. The criteria to interpret the magnitude of the ES was as follows: trivial (< 0.2), small (0.2-0.59), moderate (0.60-1.19), large (1.2-2.0), or very large (> 2.0) RESULTS: The responses of blood glucose following each protocol and OGTT was similar in all groups, reaching the glycemic peak at 30 min of recovery. However, The MV group exhibited significantly lower values in the AUC when compared with LV group over two hours monitoring period (P=0.021, ES=1.198). CONCLUSIONS: The present study showed that RT at different velocities can generate different metabolic responses. In conclusion, the results of this study indicated that RT at a high velocity could be the optimum for postprandial glucose control.

Contraction intensity-dependent variations in the responses to brain and corticospinal tract stimulation after a single session of resistance training in men.

The aim of this study was to determine the effects of acute resistance training (RT) intensity on motor-evoked potentials (MEPs) generated by transcranial magnetic brain stimulation and on cervicomedullary motor-evoked potentials (CMEPs) produced by electrical stimulation of the corticospinal tract. In four experimental sessions, 14 healthy young men performed 12 sets of eight isometric contractions of the elbow flexors at 0 (Control session), 25, 50, and 75% of the maximal voluntary contraction (MVC). Before and after each session, MEPs, CMEPs, and the associated twitch forces were recorded at rest. MEPs increased by 39% (P < 0.05 versus 25% in the control condition, Effect size (ES) = 1.04 and 1.76, respectively) after the 50% session and by 70% (P < 0.05 vs. all other conditions, ES = 0.91-2.49) after the 75% session. In contrast, CMEPs increased similarly after the 25%, 50%, and 75% sessions with an overall increase of 27% (P < 0.05 vs. control condition, ES = 1.34). The amplitude of maximal compound muscle action potentials (Mmax) was unchanged during the experiment. The MEP- and CMEP-associated twitch forces also increased after RT, but training intensity affected only the increases in MEP twitch forces. The data tentatively suggest that the intensity of muscle contraction used in acute bouts of RT affects cortical excitability.NEW & NOTEWORTHY Resistance training (RT) can acutely increase the efficacy of the corticospinal-motoneuronal synapse, motoneuron excitability and motor cortical excitability. We show that motor-evoked potential generated by transcranial magnetic stimulation but not cervicomedullary electrical stimulation increased in proportion to the intensity of training used during a single session of RT. The data suggest that the intensity of muscle contraction used in acute bouts of RT affects cortical excitability.

Effects of one resistance training session on body checking behaviors in male adults

The objective of this study is to analyse the effects of a session of resistance training on body checking in male adults. Participants included 50 volunteers aged between 18 and 30 years. A single session of resistance training was performed, and we used hypertrophy as our training method. Body checking behaviors were assessed using the Male Body Checking Questionnaire (MBCQ). Participants answered the MBCQ before (T1), immediately after (T2), and 24 h (T3), 48 h (T4) and 72 h (T5) after the resistance training session. The findings showed no difference in the subscale "compared to other people" (p=0.32). However, statistically significant differences were found for the subscales “use of reflective surface” (p=0.03), "check by clamping" (p=0.04) and "evaluation by others" (p=0.02). We concluded that a single session of resistance training was able to positively change some body checking behaviors of male adults.

Effect of carbohydrates versus carbohydrates plus proteins and antioxidants on oxidative stress and muscle damage induced by single bout resistance exercise

Although nutritional supplementation is controversial in the literature, the ergogenic value attributed to carbohydrate supplementation is recognized by delaying fatigue in resistance exercises. The aim of this study was to investigate the effect of supplementation of a commercial carbohydrate compound plus protein and antioxidants (CPA) in muscle damage and oxidative stress induced by a single resistance training session. Ten healthy young subjects (24 ± 4 years; 23.2 ± 1 kg/m2; $$ V{\text{O}}_{2\hbox{max} } $$ 44.9 ± 10 ml/kg/min) performed three series of ten exercises until concentric failure, randomly ingesting water (WAT), isolated carbohydrates (CHO) or carbohydrates associated with proteins and antioxidants (CPA). Blood samples were taken before, immediately and 24 h after each exercise session for analysis of muscle damage markers, creatine kinase (CK) and malondialdehyde (MDA) oxidative stress. Blood glucose was measured before, during and after the end of the exercises. CHO or CPA resulted in significant increases in glucose of 24 and 9.5%, respectively, at post-exercise compared to pre-exercise values. WAT resulted in a significant post-exercise increase in CK (107.6 ± 34.9–227.4 ± 82.2 U/l; p = 0.02), while CHO promoted no significant increase (226 ± 90–318 ± 190 U/l; p = 0.02) and CPA did not promote a significant reduction (130 ± 125–121 ± 83 U/l). CHO or CPA did not affect the concentration of lipid peroxidation. This study revealed that ingestion of CHO or CPA during resistance exercise decreases muscle damage, but does not influence the lipidic peroxidation marker MDA.

The acute effect of Quercetin on muscle performance following a single resistance training session.

To examine the effect of acute quercetin (Q) ingestion on neuromuscular function, biomarkers of muscle damage, and rate of perceived exertion (RPE) in response to an acute bout of resistance training. 10 young men (22.1 ± 1.8 years, 24.1 ± 3.1 BMI) participated in a randomized, double-blind, crossover study. Subjects consumed Q (1g/day) or placebo (PLA) 3h prior to a resistance training session which consisted of 3 sets of 8 repetitions at 80% of the one repetition maximum (1RM) completed bilaterally for eight different resistance exercises. Electromyographic (EMG) signals were recorded from the knee extensor muscles during maximal isometric (MVIC) and isokinetic voluntary contractions, and during an isometric fatiguing test. Mechanical and EMG signals, biomarkers of cell damage, and RPE score were measured PRE, immediately POST, and 24h (blood indices only) following the resistance exercise. After a single dose of Q, the torque-velocity curve of knee extensors was enhanced and after the resistance exercise, subjects showed a lower MVIC reduction (Q: 0.91 ± 6.10%, PLA: 8.66 ± 5.08%) with a greater rate of torque development (+ 10.6%, p < 0.005) and neuromuscular efficiency ratio (+ 28.2%, p < 0.005). Total volume of the resistance exercises was significantly greater in Q (1691.10 ± 376.71 kgrep) compared to PLA (1663.65 ± 378.85 kgrep) (p < 0.05) with a comparable RPE score. No significant differences were found in blood marker between treatments. The acute ingestion of Q may enhance the neuromuscular performance during and after a resistance training session.

AORTIC POST-RESISTANCE EXERCISE HYPOTENSION IN PATIENTS WITH PERIPHERAL ARTERY DISEASE

ABSTRACT Introduction: A single session of resistance training decreases brachial blood pressure (BP) in patients with peripheral artery disease (PAD). However, it is not known whether similar responses occur in aortic BP, which is a better predictor of cardiovascular risk. Objective: This study aimed to analyze the effects of a single session of resistance training on aortic BP in PAD patients. Methods: This randomized, crossover, controlled trial involved 16 patients. All of them performed a session of resistance training (R - 3 x 10 reps in eight exercises, 5-7 on the OMNI Scale) and a control session (C - resting for 50 min). Before and after each session, aortic BP was assessed by applanation tonometry technique. Results: There was an increase in systolic (P&lt;0.002) and mean (P&lt;0.001) aortic BP in both sessions; however, higher increases were observed in C session (P&lt;0.001). Additionally, diastolic aortic BP only increased after C session (P=0.004). The hypotensive effect of the exercise on systolic, diastolic, and mean aortic BP were -12±2, -6±2, and -7±2 mmHg, respectively. Conclusion: A single session of resistance training promoted a hypotensive effect on aortic BP of patients with PAD, indicating an acute reduction in cardiovascular risk in this population. Level of Evidence I; Therapeutic studies - Investigating the results of treatment.

Effect of Ziziphus jujuba Supplementation before One Session of Acute Resistance Exercise on the Serum Glutathione Peroxidase and Superoxide Dismutase Activity

Aims: Intense exercise damages tissues and disturb some cellular processes through oxidative stress and antioxidants can modulate intense exerciseinduced oxidative stress. The aim of the present study was to examine the effect of Ziziphus jujube supplements on the glutathione peroxidase (GPX) and superoxide dismutase (SOD) activity in serum after a single session of resistance training. Materials & Methods: In this semi-experimental study, 24 young non-athletes females were purposefully selected and were randomly divided into two groups; Ziziphus jujube consumption+intensive resistance exercise and intensive resistance exercise. The first group received 0.4g/kg of body weight of Ziziphus jujube daily for 3 weeks, but another group prohibited from Ziziphus jujube consumption. Both groups carried out a session of intensive resistance exercise consisting of 5 movements at 90% of one maximum repetition. Blood samples were measured in three phases; baseline, after 3 weeks of the Ziziphus jujube consumption, and after the resistance exercise session. In order to valuation the enzymes activity the enzymatic method was used. Data were analyzed by the repeated measures ANOVA and LSD tests in SPSS 22 software. Findings: The Ziziphus jujube supplement significantly increased GPX activity (p=0.001) but it had no significant (p=0.19) influence on SOD activity. In addition, intensive resistance training significantly decreased the SOD (p=0.03) and GPX (p=0.02) activity immediately after exercise. Conclusion: Using Ziziphus jujube supplements improves the antioxidant enzyme activity of GPX, but this improvement is not likely enough to inhibit the depression of the antioxidant status after performing resistance exercise.

Is the Self-Selected Resistance Exercise Intensity by Older Women Consistent With the American College of Sports Medicine Guidelines to Improve Muscular Fitness?

The purpose of this study was to verify the self-selected intensity during resistance training (RT) in older women. Twenty healthy women (mean age, 65.6 years) underwent a 2-week familiarization period followed by 3 experimental sessions. During the first session, anthropometric measurements were taken. The second session involved completion of a 1 repetition maximum (1RM) test for the following exercises: chest press, leg press, lat pull-down, leg extension, lateral shoulder raise, leg curl, biceps curl, and triceps pushdown. Last, a single RT session was performed at a self-selected intensity. During the RT session, participants were instructed to self-select a load for performing 3 sets of 10-15 repetitions. Data were analyzed by mean (SD) and analysis of variance with repeated measures (p < 0.05). Global mean of the 3 sets was bench press 41.0% 1RM (11.9), leg press 43.0% 1RM (17.2), lat pull-down 47.2% 1RM (11.1), leg extension 33.0% 1RM (8.1), lateral shoulder raise 51.1% 1RM (12.1), leg curl 43.5% 1RM (8.8), biceps curl 48.0% 1RM (15.5), and triceps pushdown 51.7% 1RM (13.3); there were no significant differences between the sets (p > 0.05). These results indicate that inactive older women self-selected an intensity exercise during RT below the recommendation for improvements on muscle fitness in apparently healthy older adults. However, this intensity is recommended for very deconditioned individuals. Nevertheless, the use of self-selection strategy during an exercise program can have greater advantages because of its easy applicability, its positive relation with exercise adherence, and for promoting initial muscle conditioning in older adults. Furthermore, it is crucial to gradually increase the RT load to guarantee better and sustainable effects on muscle fitness. Finally, future studies are needed to establish the chronic effects of RT at self-selected intensity on muscle fitness and the functional health of older adults.

Reply to Scott, Sale, Greeves, and Fraser

to the editor: We thank Scott et al.([1][1]) for their interest in our recent study ([2][2]) that examined the acute response of bone turnover markers to a single bout of resistance training (RT) or plyometrics (PLY). We appreciate the acknowledgement of the strengths of our study design: we

Efeito de uma sessão de exercício resistido na sensibilidade cutânea em idosas hipertensas e normotensas fisicamente ativas. 10.5007/1980-0037.2011v13n6p409

The aim of this study was to analyze the effect of a single session of resistance training on skin sensitivity in physically active, hypertensive and normotensive older women, as well as compare skin sensitivity in both groups. Thirty-two physically active women (mean age 65.8 } 5.1 years; weight, 69.5 } 13.7 kg; height, 1.60 } 0.1 m) participated in this study and were classified as hypertensive (n = 15) or normotensive (n = 17). All participants answered a clinical history questionnaire and the Modified Baecke Questionnaire for Older Adults. Before and after the resistance training session, the skin sensitivity of the dominant hand was assessed at seven anatomical sites on the dorsal and palmar surfaces by stimulation with a Semmes-Weinstein monofilament esthesiometer. The loads employed during the resistance training session were determined one week before the experimental protocol. The Wilcoxon test showed no statistically significant differences in the skin sensibility test before and after resistance training in either groups. However, the Mann-Whitney U revealed a statistically significant between-group difference in sensitivity at three sites before resistance training and at only site post-training. A single session of resistance training had no effect on the skin sensitivity of hypertensive and normotensive older women. However, hypertensive participants exhibited reduced skin sensibility at some anatomical sites as compared with normotensive women.

Resistance exercise-induced increase in muscle mass correlates with p70S6 kinase phosphorylation in human subjects

The purpose of the present study was to investigate the possible relationship between a change in Thr(389) phosphorylation of p70S6 kinase (p70(S6k)) after a single resistance training session and an increase in skeletal muscle mass following short-term resistance training. Eight male subjects performed an initial resistance training session in leg press, six sets of 6RM with 2 min between sets. Muscle biopsies were obtained from the vastus lateralis before (T1) and 30 min after the initial training session (T2). Six of these subjects completed a 14-week resistance-training programme, three times per week (nine exercises, six sets, 6RM). A third muscle biopsy was obtained at the end of the 14-week training period (T3). One repetition maximum (1RM) squat, bench press and leg press strength as well as fat-free mass (FFM, with dual energy X-ray absorptiometry) were determined at T1 and T3. The results show that the increase in Thr(389) phosphorylation of p70(S6k) after the initial training session was closely correlated with the percentage increase in whole body FFM (r = 0.89, P < 0.01), FFM(leg) (r = 0.81, P < 0.05), 1RM squat (r = 0.84, P < 0.05), and type IIA muscle fibre cross sectional area (r = 0.82, P < 0.05) after 14 weeks of resistance training. These results may suggest that p70(S6k) phosphorylation is involved in the signalling events leading to an increase in protein accretion in human skeletal muscle following resistance training, at least during the initial training period.

Glucose Uptake Following Resistance Training Sessions of Different Intensities but of Equal Work Volume

Acute exercise and exercise training can have positive effects on insulin sensitivity and glucose uptake in healthy and glucose-intolerant subjects. An interest in resistance training and its effects on glucose uptake has increased in recent years. Past studies have indicated that high-intensity resistance exercise augments post-exercise glucose uptake to a greater degree than low-intensity resistance exercise. However, few studies have equated the work volumes among intensity levels, making it difficult to differentiate whether the resultant increased glucose uptake was due to the exercise intensity or the amount of work completed. To date, little is known about the effects that different exercise intensities, of equal workloads during a single session of resistance training, may have on glucose uptake. PURPOSE: To compare the effect of acute low- and high-intensity resistance exercise of equal work volume on glucose uptake in resistant-trained males. METHODS: Fifteen healthy male (22.9±3.8 y), resistance-trained (6.7 ±3.9 y) subjects completed three treatment sessions: CON (no-exercise control), HI (3 × 8, 85% 10-RM), and LO (3x15, 45% 10-RM). Exercise sessions consisted of eight resistance exercises. Glucose uptake was measured the following morning by hyperinsulinemic euglycemic clamp technique. Glucose disposal was measured by analyzing the glucose infusion rate during the final 30 minutes of steady-state blood glucose concentrations. Insulin sensitivity was calculated by dividing the glucose infusion rate by the average insulin infusion. RESULTS: Fasting blood glucose levels did not change among treatment sessions (CON=80.5± 5.3 vs. HI=77.0±4.9 vs. LO=77.1±6.0 mg/dl). Glucose uptake was not significantly different among treatment sessions (CON=11.3±3.0 vs. HI=11.7±2.7 vs. LO=11.4±2.8 mg/kgFFM/min). Insulin sensitivity did not change among treatment sessions [CON=0.26±0.09 vs. HI=0.28±0.07 vs. LO=0.27±0.06 (mg/kgFFM/min) / (uU/ml)]. CONCLUSIONS: These data indicate that for acute resistance exercise bouts with an equated work volume, low- and high-intensity sessions have similar effects on glucose uptake, but are no different than a no-exercise control session in resistance-trained men. The trained status of the subjects may have allowed for maximum training-induced cellular adaptations for enhanced insulin sensitivity and glucose uptake. Further investigations utilizing untrained males are warranted to further clarify the effects of intensity and workload on glucose uptake. Supported by the National Strength and Conditioning Association, the VCU-GCRC (M01 RR00065, NCRR, NIH), and the VCU School of Education

ARTERIAL AND VENOUS AMINO ACID CONCENTRATIONS AND PROTEIN BALANCE AFTER A RESISTANCE TRAINING SESSION

Increase in skeletal muscle size with resistance exercise training represents a fundamental biologic adaptation to an increased workload. Such hypertrophy results from changes in the rates of protein synthesis and/or breakdown. After a single resistance training session (RTS) both protein synthesis and protein breakdown occur and net balance is either positive or negative. PURPOSE: To assess the effects of RTS on arterial and venous free amino acid concentrations and protein balance in male subjects. METHODS: Both the exercise group (EG) and the control group (CG) consisted of six healthy physically active males. On the measurement day in fasting conditions stable isotopic tracer of L-[ring-2H5] phenylalanine was infused during the experiment and enrichment was analysed by GC/MS. EG started a heavy hypertrofic 50 minute RTS for lower extremities 55 minutes after infusion. At the same time CG was at rest. Blood samples were drawn from femoral artery and vein before infusion and at 135, 145, 155 and 165 and 270, 280, 290 and 300 minutes and muscles samples from the vastus lateralis muscle at 165 and 300 minutes after infusion. A three-compartment model was used for determination of leg muscle protein kinetics. Blood samples for amino acids (n = 18) were analysed by HPLC. Subjects recorded their dietary intake for 5 days and training for 2 weeks before the experiment day. RESULTS: There were no significant differences between the groups in the arterial and venous concentrations of all free amino acids. After RTS both protein synthesis and breakdown were greater (p < 0.05) in EG than in CG resulting in similar negative protein net balance in both groups (−23 ± 9 nmol phe min−1 100 ml leg volume−1 for EG and -21 ± 3 nmol phe min−1 100 ml leg volume−1 for CG). Dietary intake and training were similar in the groups. CONCLUSION: These results indicate that RTS induced in fasting conditions a similar response in protein net balance as occurred at rest. Simultaneously arterial and venous free amino acid concentrations were similar after RTS and at rest. Supported by TEKES 40721/00.