Sets Of Resistance Exercise Research Articles

Motor cortex tDCS does not modulate perceived exertion within multiple-sets of resistance exercises

BACKGROUND: Recent evidences have shown that the motor cortex (MC) may influence the rating of perceived exertion (RPE). Given the potential role of transcranial direct current stimulation (tDCS) in modulate cortical areas related to exercise performance, it is possible that tDCS applied on motor cortex (MC) could also influence the RPE during resistance exercises. OBJECTIVE: This study analyzed the effects of transcranial direct current stimulation on the rating of perceived exertion during multiple sets of resistance exercises. METHODS: Thirteen strength-trained men performed a resistance exercise session after either anodal tDCS or sham stimulation applied over the primary motor cortex. Resistance exercise sessions included 3 sets of 10 repetitions of 6 exercises performed with load of at 85% of 8–12 RM. The RPE was obtained using OMNI-Resistance exercise scale. RESULTS: The RPE assessed at the end of the sessions was similar in tDCS vs. sham condition (6.78 ± 1.48 vs. 6.87 ± 1.49, respectively; p = 0.56). The RPE for each exercise was similar across conditions, except for the second set of bench press (p = 0.04) and first set of seated-row (p = 0.03). CONCLUSION: In conclusion, the RPE during multiple sets of submaximal exercises was not modulated by tDCS applied upon

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<.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.

Palm Cooling and Heating Delays Fatigue During Resistance Exercise In Women

We previously reported that cold application to the palms between sets of high-intensity bench press exercise produces an ergogenic effect in men. In this study, we hypothesized that palm cooling (PC) or heating during rest intervals between high-intensity weight training sets will increase total repetitions and exercise volume load (kilograms) in resistance trained female subjects in a thermoneutral (TN) environment. Eight female subjects (mean ± SD, age = 25 ± 6 years, height = 160 ± 6 cm, body mass = 56 ± 7 kg, 1-repetition maximum [1RM] = 52 ± 6 kg, weight training experience = 6 ± 2 years) completed 4 sets of 85% 1RM bench press exercise to failure, with 3-minute rest intervals. Exercise trials were performed in a counterbalanced order on 3 days, separated by at least 3 days in TN, Palm heating (PH), and PC conditions. Heating and cooling were applied by placing both hands in a hand cooling device with the hand plate set to 45° C for heating and 10° C for cooling. Data were analyzed using a 2-factor repeated-measures analysis of variance and Tukey's post hoc tests. Palm cooling repetitions were significantly higher than TN repetitions during the second set, and PH repetitions were significantly higher than those of TN during the fourth set. Total exercise volume load (kilograms) for both PC (1,387 ± 358) and PH (1,349 ± 267) were significantly higher than TN (1,187 ± 262). In women, both heating and cooling of the palms between sets of resistance exercise increased the total exercise volume load performed. This ergogenic response to a peripheral sensory input is consistent with the central governor theory of muscular fatigue.

Dose-response of 1, 3, and 5 sets of resistance exercise on strength, local muscular endurance, and hypertrophy.

The study's purpose was to compare the response of performing 1, 3, and 5 sets on measures of performance and muscle hypertrophy. Forty-eight men, with no weight training experience, were randomly assigned to one of the 3 training groups, 1 SET, 3 SETS, 5 SETS, or control group. All training groups performed 3 resistance training sessions per week for 6 months. The 5 repetition maximum (RM) for all training groups increased in the bench press (BP), front lat pull down (LPD), shoulder press (SP), and leg press (LP) (p ≤ 0.05), with the 5 RM increases in the BP and LPD being significantly greater for 5 SETS compared with the other training groups (p ≤ 0.05). Bench press 20 RM in the 3-SET and 5-SET groups significantly increased with the increase being significantly greater than the 1-SET group and the 5-SET group increase being significantly greater than the 3-SET group (p ≤ 0.05). LP 20 RM increased in all training groups (p ≤ 0.05), with the 5-SETS group showing a significantly greater increase than the 1-SET group (p ≤ 0.05). The 3-SET and 5-SET groups significantly increased elbow flexor muscle thickness (MT) with the 5-SET increase being significantly greater than the other 2 training groups (p ≤ 0.05). The 5-SET group significantly increased elbow extensor MT with the increase being significantly greater than the other training groups (p ≤ 0.05). All training groups decreased percent body fat, increased fat-free mass, and vertical jump ability (p ≤ 0.05), with no differences between groups. The results demonstrate a dose-response for the number of sets per exercise and a superiority of multiple sets compared with a single set per exercise for strength gains, muscle endurance, and upper arm muscle hypertrophy.

Muscle activation does not increase after a fatigue plateau is reached during 8 sets of resistance exercise in trained individuals.

The premise of eliciting the greatest acute fatigue is accepted and used for designing programs that include excessive, potentially dangerous volumes of high-intensity resistance exercise. There is no evidence examining acute fatigue and neuromuscular responses throughout multiple sets of moderate-to-high intensity resistance exercise. Fifteen resistance-trained male subjects performed a single exercise session using 8 sets of Bulgarian split squats performed at 75% maximal force output. Maximal force output (N) was measured after every set of repetitions. Electromyographic (EMG) activity of vastus lateralis was monitored during all force trials and exercise repetitions. Repetitions per set decreased from the first to the third set (p < 0.001). Maximal force output decreased from preexercise to set 4 (p < 0.001). Electromyographic amplitudes during exercise did not change. Secondary subgroup analysis was performed based on the presence, or not, of a fatigue plateau (<5% reductions in maximal force output in subsequent sets). Nine participants exhibited a fatigue plateau, and 6 did not. Participants who plateaued performed less first-set repetitions, accrued less total volume, and did not exhibit increases in EMG amplitudes during exercise. Initial strength levels and neuromuscular demand of the exercise was the same between the subgroups. These data suggest that there are individual differences in the training session responses when prescribing based off a percentage of maximal strength. When plateaus in fatigue and repetitions per set are reached, subsequent sets are not likely to induce greater fatigue and muscle activation. High-volume resistance exercise should be carefully prescribed on an individual basis, with intrasession technique and training responsiveness continually monitored.

Impact of single and multiple sets of resistance exercise in type 1 diabetes

To examine glycemic and glucoregulatory responses to resistance exercise (RE) sessions of different volume in type 1 diabetes (T1DM). Eight T1DM (seven males: one female; age: 38 ± 6 years, HbA1C : 8.7 ± 1.0%/71 ± 11 mmol/mol) attended the research facility fasted and on four separate occasions, having taken their usual basal insulin, but omitted morning rapid-acting insulin. Participants completed a 1SET (14 min), 2SET (28 min), 3SET (42 min) RE session (eight exercises × 10 repetitions) at 67 ± 3% one-repetition-maximum followed by 60-min recovery, or a resting trial (CON). Venous blood samples were taken before and after exercise. Data (mean ± SEM) were analyzed using repeated-measures analysis of variance (P ≤ 0.05). RE did not induce hypoglycemia (BG < 4 mmol/L). During recovery, blood glucose (BG) concentrations remained above pre-exercise after 1SET (15-60 min, P < 0.05) and 2SET (0-60 min, P < 0.05) but comparable (P > 0.05) with pre-exercise after 3SET. BGIAUC(area-under-curve) (mmol/L/60 min) was greater after 1SET and 2SET vs CON (1SET 103.6 ± 36.9 and 2SET 128.7 ± 26.1 vs CON -24.3 ± 15.2, P < 0.05), but similar between 3SET and CON (3SET 40.7 ± 59.3, P > 0.05). Under all trials, plasma creatine kinase levels at 24 h post-exercise were similar (P > 0.05) to pre-exercise. RE does not induce acute hypoglycemia or damage muscle. BG progressively rose after one and two sets of RE. However, inclusion of a third set attenuated exercise-induced hyperglycemia and returned BG to that of a non-exercise trial.

ACUTE RESPONSES OF RATE PRESSURE PRODUCT IN SETS OF RESISTANCE EXERCISE

Objective: To compare the acute responses of rate pressure product (RPP) between dynamic and isometric sets of resistance exercise (RE); compare the acute responses of RPP between upper and lower limbs in RE. Methods: Nineteen active men (22.7 ± 2.2 years) attended this study in a random crossover model. In the first day they performed hemodynamic measurements and one maximum repetition tests (1RM) in leg press (LGP) and bench press (BCP) exercises. In the second, third, fourth and fifth days they performed the following tests: LGP isometric, BCP isometric, LGP dynamic and BCP dynamic, respectively. Isometric protocols were conducted in 3 sets of 40 s (1 st set: 25% 1RM, 2 nd set: 50% 1RM, 3 rd set: 75% 1RM) and dynamic protocols in 3 sets of 10 repetitions (1 st set: 25% 1RM, 2 nd set: 50% 1RM, 3 th set: 75% 1RM). The RPP was obtained immediately after each set. Results: A comparison between protocols showed that RPP was higher (P < 0.05) in dynamic than in isometric protocol. A comparison between exercises showed that RPP was higher (P < 0.05) in LGP than BCP exercise. Conclusions: In similar relative intensities, the acute cardiac responses are influenced by the exercise protocol, since the RPP was higher in the dynamic condition. Furthermore, RPP seems to be related with recruited muscle mass, since that were observed higher values of RPP in exercises for lower limbs .

Combined exercise circuit session acutely attenuates stress-induced blood pressure reactivity in healthy adults

ObjectiveTo investigate the blood pressure (BP) responses to cardiovascular stress test after a combined exercise circuit session at moderate intensity. MethodTwenty individuals (10 male/10 fem; 33.4± 6.9 years; 70.2± 15.8 kg; 170.4± 11.5 cm; 22.3± 6.8% body fat) were randomized in a different days to control session with no exercise or exercise session consisting of 3 laps of the following circuit: knee extension, bench press, knee flexion, rowing in the prone position, squats, shoulder press, and 5 min of aerobic exercise at 75-85% of age-predicted maximum heart rate and/or 13 on the Borg Rating of Perceived Exertion [scale of 6 to 20]. The sets of resistance exercise consisted of 15 repetitions at ~50% of the estimated 1 repetition maximum test. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured at rest and during 1h of recovery in both experimental sessions. After that, blood pressure reactivity (BPR) was evaluated using the Cold Pressor Test. ResultsDuring 1h of exercise recovery, there was a reduction in SBP (3-6 mmHg) and DBP (2-5 mmHg) in relation to pre-session rest (p<0.01), while this reduction was not observed in the control session. A decline in BPR (4-7 mmHg; p<0.01) was observed 1h post-exercise session, but not in the control session. Post-exercise reductions in SBP and DBP were significantly correlated with BPR reductions (r=0.50-0.45; p<0.05). ConclusionA combined exercise circuit session at moderate intensity promoted subsequent post-exercise hypotension and acutely attenuated BPR in response to a cardiovascular stress test. In addition, the post-exercise BP reduction was correlated with BPR attenuation in healthy adults of both genders.

Effects of Rest Interval Length on Smith Machine Bench Press Performance and Perceived Exertion in Trained Men

This study compared two different rest intervals (RI) between sets of resistance exercise. Ten resistance-trained men (M age = 24.3, SD = 3.5 yr.; M weigh t= 80.0 kg, SD = 15.3; M height = 1.75 m, SD = 0.04) performed five sets of Smith machine bench presses at 60% of one repetition maximum, either with 1.5 min. or 3 min. RI between sets. Their repetition performance, total training volume, velocity, fatigue, rating of perceived exertion, and muscular power were measured. All of these measures indicated that performance was significantly better and fatigue was significantly lower in the 3 min. RI as compared with the 1.5 min. RI, except the rating of perceived exertion which did not show a significant difference. A longer RI between sets promotes superior performance for the bench press.

Influence of continuous or intermittent blood flow restriction on muscle activation during low-intensity multiple sets of resistance exercise

Low-intensity resistance exercise with blood flow restriction (BFR) has been shown to induce a prominent increase in muscle activation in response to muscle fatigue. However, the magnitude of muscle fatigue between continuous (Con-BFR) and intermittent BFR (Int-BFR, BFR only during exercise) is currently unknown. We examined the effect of Con-BFR or Int-BFR on muscle activation during exercise. Unilateral arm curl exercise (20% of one-repetition maximum, four sets, 30 sec rest period between sets) was performed without (CON) or with Con-BFR or Int-BFR. During BFR conditions, the cuff was inflated to 160 mmHg on the proximal region of testing arm. Surface electromyography (EMG) was recorded from the biceps brachii muscle, and integrated EMG (iEMG) was analyzed. During the exercise, iEMG increased progressively in Con-BFR and Int-BFR and both conditions were greater (p < 0.05) than CON at the 3rd and 4th set. However, there were no differences (p > 0.05) in iEMG between Con-BFR and Int-BFR during exercise (∼2.45 and ∼2.40 times, respectively). Thus, the magnitude of increase in muscle activation may be similar between Con-BFR and Int-BFR when BFR exercise was performed at a high level of cuff pressure intensity.

Neuromuscular and metabolic responses to three different resistance exercise methods.

The aim of this study was to compare the effect of resistance exercise with three different methods on integrated electromyography (IEMG) and metabolic responses in recreational athletes. Twenty four males (mean 23.59±0.87 years) were randomly assigned to three experimental groups. Participants performed knee extension exercises: Slow (SL: 3-3, 3s for each concentric and eccentric action with 50% of 1 RM), Normal (NH: 1-1, 1 s for each concentric and eccentric action 80% of 1 RM) and Traditional (TH: 2-4, 2s for concentric and 4s for eccentric action with 80% of 1 RM). Plasma lactate, glucose and triglyceride concentration and IEMG was measured before and immediately after performing four sets of resistance exercise. Each method significantly decreased IEMG (P<0.05), but there was no significant difference between groups. Lactate was increased following TH and NH more than SL method (P<0.05). Each method significantly increased plasma glucose (P<0.05). Work considering time under tension (workTUT) was higher (P<0.05) during TH method than the other methods and during SL it was higher than NH method (P<0.05). Volume load was higher (P<0.05) during NH than the other two methods and during TH it was higher than SL method (P<0.05). These results indicate that exercise intensity during the resistance exercise is important for the enhancement of lactate responses, but the slow resistance exercise method could induce acute neuromuscular response as much as high intensity methods. It seems that this method will be advantageous for those who want to increase acute neuromuscular changes with low exercise intensity and volume.

Physiological and metabolic responses as function of the mechanical load in resistance exercise

The present study aimed to investigate the relationship between the mechanical load during resistance exercise and the elicited physiological responses. Ten resistance-trained healthy male subjects performed 1 set of resistance exercise each at 55%, 70%, and 85% of 1 repetition maximum for as many repetitions as possible and in 4 training modes: 4-1-4-1 (4 s concentric, 1 s isometric, 4 s eccentric, and 1 s isometric successive actions), 2-1-2-1, 1-1-1-1, and explosive (maximum velocity concentric). Mean concentric power and total concentric work were determined. Oxygen uptake (V̇O2) was measured during exercise and for 30 min post exercise. Total volume of consumed oxygen (O2 consumed) and excess post-exercise oxygen consumption (EPOC) were calculated. Maximum blood lactate concentration (LAmax) was also determined. V̇O2 exhibited a linear dependency on mean concentric power. Mean concentric power did not have a detectable effect on EPOC and LAmax. An augmentation of total concentric work resulted in significant linear increase of O2 consumed and EPOC. Total concentric work caused a significant increase in LAmax. In general, a higher mechanical load induced a larger physiological response. An increase in mean concentric power elicited higher aerobic energy turnover rates. However, a higher extent of total concentric work augments total energy cost covered by oxidative and (or) glycolytic pathways.

EFFECTS OF DIFFERENT ANTAGONIST PROTOCOLS ON REPETITION PERFORMANCE AND MUSCLE ACTIVATION – ORGINAL RESEARCH

Objective: To investigate the acute effects of different antagonist manipulation protocols on maximal repetition performance and muscle activation during seated row (SR) exercise. Methods: Fifteen men (22.4 ± 1.1 years old, height 175 cm ± 5.5, weight 76.6 kg ± 7, and 12.3 ± 2.1 of body fat percentage) with previous resistance training experience (3.5 ± 1.2 years) performed four experimental protocols: (TP) one set to repetition failure of SR exercise; (AS) Antagonist static stretching for the pectoralis major (PM) followed by one set of SR; (PNFA) Proprioceptive neuromuscular facilitation for PM followed by one set of the SR; (APS) One set of the bench press with a 10 RM loads followed by one set of the SR. The maximal repetitions and the electromyographic (EMG) signal were recorded for the latissimus dorsi (LD), biceps brachii (BB), triceps brachii lateral head (TL), and PM during the SR. Results: A significant increase in SR repetition performance was noted for the APS (14 ± 1) versus the TP (9 ± 1.2, P = 0.0001), PNFA (10 ± 1.5, P = 0.001), and AS (12 ± 1.5, P = 0.004) protocols. A significant increase in SR repetitions was also noted for the AS versus the TP (P = 0.001) and PNFA (P = 0.002) protocols. The muscle activation of the BB and LD were significantly higher during the APS and AS versus the PNFA and TP sessions. Conclusions: These results suggest that either using the APS or AS approaches can facilitate an increase in SR repetition performance versus traditional resistance exercise sets.

COMPARATIVE PERFORMANCE AND LACTATE DATA FROM BENCH PRESSES AT SUBMAXIMAL LOADS

Objective: To investigate the acute effects of different antagonist manipulation protocols on maximal repetition performance and muscle activation during seated row (SR) exercise. Methods: Fifteen men (22.4 ± 1.1 years old, height 175 cm ± 5.5, weight 76.6 kg ± 7, and 12.3 ± 2.1 of body fat percentage) with previous resistance training experience (3.5 ± 1.2 years) performed four experimental protocols: (TP) one set to repetition failure of SR exercise; (AS) Antagonist static stretching for the pectoralis major (PM) followed by one set of SR; (PNFA) Proprioceptive neuromuscular facilitation for PM followed by one set of the SR; (APS) One set of the bench press with a 10 RM loads followed by one set of the SR. The maximal repetitions and the electromyographic (EMG) signal were recorded for the latissimus dorsi (LD), biceps brachii (BB), triceps brachii lateral head (TL), and PM during the SR. Results: A significant increase in SR repetition performance was noted for the APS (14 ± 1) versus the TP (9 ± 1.2, P = 0.0001), PNFA (10 ± 1.5, P = 0.001), and AS (12 ± 1.5, P = 0.004) protocols. A significant increase in SR repetitions was also noted for the AS versus the TP (P = 0.001) and PNFA (P = 0.002) protocols. The muscle activation of the BB and LD were significantly higher during the APS and AS versus the PNFA and TP sessions. Conclusions: These results suggest that either using the APS or AS approaches can facilitate an increase in SR repetition performance versus traditional resistance exercise sets.

Planned Intensity Reduction to Maintain Repetitions Within Recommended Hypertrophy Range

The authors tested different loading schemes for the number of repetitions completed during multiple sets of resistance exercise. Twenty-four resistance-trained men (age 24.0 ± 4.5 y, body mass 78.3 ±10.2 kg, height 177 ± 7 cm) were tested over a 5-wk period. During week 1 a 10-repetition maximum (10RM) in the leg press was determined. During weeks 2-5 subjects completed 4 bouts of leg presses, in a randomized fashion, consisting of 4 sets with 60 s of interset rest. Set 1 of each bout was performed with 10RM, with differing intensity for sets 2-4 as follows: (1) 10RM load for all sets (CON), (2) 5% load reduction after each set (RED 5), (3) 10% load reduction after each set (RED 10), and (4) 15% load reduction after each set (RED 15). Significant (P < .05) decreases in repetitions completed across sets were observed in CON (sets 2, 3, and 4) and RED 5 (sets 3 and 4). Significant increases in repetitions completed across sets (2, 3, and 4) were observed in RED 10 and RED 15 (P < .05). RED 5 (8.3 ± 0.9 repetitions) and RED 10 (12.0 ± 1.1 repetitions) allowed subjects to maintain the majority (>60%) of sets in the range of 8-12 repetitions, whereas both CON and RED 15 resulted in <50% of sets in the range of 8-12 repetitions, with the majority of sets performed <8 repetitions for CON and >12 repetitions for RED 15. Reducing load 5-10% in each set should allow maintenance of 8-12RM loads for most sets of resistance exercise.

Thomas L. DeLorme and the Science of Progressive Resistance Exercise

In the latter years of the Second World War, the number of American servicemen who had sustained orthopedic injuries was overwhelming the nation's military hospitals. The backlog of patients was partly because of the sheer number of soldiers involved in the war effort, but it was exacerbated by rehabilitation protocols that required lengthy recovery times. In 1945, an army physician, Dr. Thomas L. DeLorme experimented with a new rehabilitation technique. DeLorme had used strength training to recover from a childhood illness and reasoned that such heavy training would prove beneficial for the injured servicemen. DeLorme's new protocol consisted of multiple sets of resistance exercises in which patients lifted their 10-repetition maximum. DeLorme refined the system by 1948 to include 3 progressively heavier sets of 10 repetitions, and he referred to the program as "Progressive Resistance Exercise." The high-intensity program was markedly more successful than older protocols and was quickly adopted as the standard in both military and civilian physical therapy programs. In 1951, DeLorme published the text Progressive Resistance Exercise: Technic and Medical Application, which was widely read by other physicians and medical professionals. The book, and DeLorme's academic publications on progressive resistance exercise, helped legitimize strength training and played a key role in laying the foundation for the science of resistance exercise.

Cardiovascular and perceptual responses to blood‐flow‐restricted resistance exercise with differing restrictive cuffs

The purpose of this study was to determine (i) the cardiovascular responses to acute blood-flow-restricted (BFR) resistance exercise and (ii) the influence of applied BFR cuff type on the cardiovascular and perceptual responses. In a randomized, crossover design, 27 participants wore either a 5·0cm wide elastic cuff or a 13·5cm wide non-elastic cuff around the thigh while performing four sets of knee extension exercise using 20% of 1-RM. Brachial and central blood pressure (BP) and aortic augmentation index (AIx) were measured before and after the restrictive cuffs were applied and inflated, after the 2nd and 4th set of resistance exercise, and 5 and 15min following the 4th set of exercise. Ratings of perceived exertion and pain were obtained before exercise and after the 2nd and 4th set of exercise. Both brachial and central BPs increased and AIx decreased during BFR exercise but returned to baseline levels within 15min following exercise. The wide cuffs caused a greater elevation in heart rate, brachial and central BPs, perceived effort and pain and a greater decrease in AIx during the BFR exercise. These findings suggest that low-intensity BFR resistance exercise does not appear to acutely negatively affect the vasculature. Also, cuff type will greatly affect cardiovascular and perceptual responses to BFR resistance exercise and thus is an important consideration in study design.

Acute l-arginine supplementation increases muscle blood volume but not strength performance

l-Arginine (L-arg) is an amino acid precursor to nitric oxide (NO). Dietary supplements containing L-arg have been marketed with the purpose of increasing vasodilation, thereby elevating blood flow to the exercising muscle and enhancing the metabolic response to exercise. Our goal was to identify the acute effect of L-arg supplementation on biceps strength performance, indicators of NO production (nitrite and nitrate - NOx), and muscle blood volume (Mbv) and oxygenation (Mox) during recovery from 3 sets of resistance exercise. Fifteen males participated in a randomized, double-blind, placebo-controlled study. After withdrawing resting blood samples, the subjects were supplemented with 6 g of L-arg (ARG) or placebo (PLA). Monitoring of Mbv and Mox with near-infrared spectroscopy began 30min after supplementation and lasted for 60min. The exercise protocol (3 sets of 10 maximal voluntary contractions of isokinetic concentric elbow extension at 60°·s(-1), 2-min rest between sets) was initiated 80min after supplementation. Blood samples were drawn at 30, 60, 90, and 120min after supplementation. Repeated measures ANOVA showed that Mbv significantly (p≤ 0.05) increased in ARG compared with the PLA during the recovery period of each set of resistance exercise. NOx, Mox, peak torque, total work, and set total work were not significantly different between groups. We found that acute L-arg supplementation increases Mbv during recovery from sets of resistance exercise with no increase in strength performance. It is still premature to recommend nutritional supplements containing L-arg as an ergogenic aid to increase muscle strength during resistance training in healthy subjects.

Commentary

Our randomized controlled trial showed a reduction of neck/shoulder pain and headache in response to 10 weeks of resistance training performed for 2 minutes a day (1, 2). We used a pragmatic approach and did not investigate the mechanism of pain reduction. It is well known that placebo can influence subjective outcomes. In the original article outlining the primary outcomes, we briefly discussed this: “Because blinding of participants in training studies is not possible, we cannot exclude the influence of placebo effects. However, the effect-size of changes in our study exceeds those previously reported in response to placebo” (2, p444). We mentioned that the effect size in our study (~0.5) exceeded those typically observed for placebo, with reference to a Cochrane Review for all clinical conditions (placebo effect size ~0.3) (3). Obviously this does not exclude that placebo effects influenced our findings. In their commentary “The placebo effect revisited”, Andersen & Mikkelsen (4) referenced a meta-analysis on osteoarthritis (OA) showing effects sizes &gt;0.5 for placebo. Our participants did not suffer from OA, but were generally healthy office workers with frequent neck/shoulder pain. In our study, we had three intervention groups: (i) 2 minutes of daily resistance training, (ii) 12 minutes of daily resistance training, (iii) weekly information on different health related aspects (control group). Because blinding is not possible in behavioral interventions and to avoid different outcome expectations between groups, we explained to the participants prior to randomization that none of the three interventions was known to be superior to the others. Of course, this does not guarantee that the three groups had similar outcome expectations. In hindsight, specific questions about outcome expectations – as suggested by Andersen & Mikkelsen (4) – could have provided additional valuable information. Due to the possible influence of placebo, studies investigating the effect of behavioral interventions on pain conditions should include outcomes other than subjective pain only. For this reason, we also included a manual palpation test on muscle tenderness performed by a physical therapist and a muscle strength test performed by an exercise physiologist. During these tests, the examiners remained blinded to group allocation. These tests showed a decrease in muscle tenderness and an increase in muscle strength at 10-week follow-up in the 2- and 12-minute groups compared with the control group (2), indicating that mechanisms beside placebo influenced our findings. Andersen & Mikkelsen (4) state in their commentary that biological effects of such brief training bouts are not plausible. In our study, the 2-minute group performed a single set of resistance exercise with as many repetitions as they could (ie, until momentary muscular fatigue). Electrophysiological measurements show that this results in marked acute neuromuscular changes (5). Several research groups have documented physiological adaptations – both neural and muscular – in response to training interventions using single-set resistance exercise for different muscle groups in healthy volunteers (6). Thus, based on the literature, it is plausible that physiological changes can occur in response to brief resistance exercises bouts. Whether such changes are causally related to pain reduction is unknown. Hopefully, our study will prompt future research on the mechanisms of pain reduction in response to brief resistance exercise bouts.

Active Intervals Between Sets of Resistance Exercises Potentiate the Magnitude of Postexercise Hypotension in Elderly Hypertensive Women

Active and passive intervals (AI, PI) between exercise series promote different hemodynamic responses; however, the impact of these intervals on the blood pressure response has not yet been investigated. The objective of this study was to compare the impact of AIs and PIs during resistance exercises with the magnitude of postexercise hypotension (PEH). Elderly hypertensive women (n = 21, 61.2 ± 2 years of age) completed 4 sessions for upper or lower limbs with AI or PI (3 sets, 15 repetitions, 60% load of 15 repetition maximum (RM), and an interval of 90 seconds between sets). Blood pressure was measured 10 minutes before and at 10, 20, 30, 40, and 50 minutes after the exercise sessions. The heart rate at the end of each AI was always significantly higher than that after the PI, but the perceived exertion as measured by the Perceived Exertion Scale (OMNI-RPE) was similar to that of PI exercise protocols. In the lower limb exercises, AI resulted in significantly and consistently higher PEH than in exercises with PI for both systolic (from 20 minutes postexercise) and diastolic (from 10 minutes postexercise) pressures. The upper limb exercises promoted much more discrete PEH in relation to the lower limb exercises, given that the AI promoted significantly higher PEH relative to the PI protocols, but only for systolic PEH and only from 30 minutes postexercise. This is the first time that AIs between sets in a session of resistance exercises have been shown to be a highly effective methodological strategy to increase PEH in elderly hypertensive women.