Multi-joint Resistance Exercise Research Articles

Carbohydrate Mouth Rinses before Exercise Improve Performance of Romanian Deadlift Exercise: A Randomized Crossover Study.

(1) Background: This study compared the effects of mouth rinsing with a carbohydrate trial (CMR) and a placebo trial (PL) on concentric and eccentric contraction strength in multi-joint resistance exercise performance. (2) Methods: Twenty healthy adult men (age: 22.4 ± 3.7 years, body mass index: 26 ± 3.8, peak power: 378.3 ± 138.7 W) were recruited in this study. Participants were employed in a double-blind, randomized crossover design to divide participants into carbohydrate mouth rinsing trial (CMR) and placebo trial (PL). After warming up, participants used 6.6% maltodextrin (CMR) or mineral water (PL) to rinse their mouth for 20 s. Next, the participants underwent tests of maximum inertial Romanian deadlift resistance exercise comprising five sets of six reps, with 3 min rests between sets. After deducting the first repetition of each set, the mean values from the five sets were analyzed. (3) Results: The concentric peak power of the CMR trial was significantly higher than that of the PL trial (p = 0.001, Cohen's d = 0.46), the eccentric peak power of the CMR trial was significantly higher than that of the PL trial (p = 0.008, Cohen's d = 0.56), and the total work of the CMR trial was significantly higher than that of PL trial (p = 0.002, Cohen's d = 0.51). (4) Conclusions: These findings demonstrate that mouth rinsing with carbohydrates before exercise can improve concentric and eccentric contraction strength in multi-joint resistance exercise performance.

Regulatory Light-Chain Phosphorylation During Weightlifting Training: Association With Postactivation Performance Enhancement.

Chiu, LZF, Fry, AC, Galpin, AJ, Salem, GJ, and Cabarkapa, D. Regulatory light-chain phosphorylation during weightlifting training: association with postactivation performance enhancement. J Strength Cond Res 37(10): e563-e568, 2023-Postactivation performance enhancement has been reported for multijoint resistance exercise, with both neural and intrinsic muscle mechanisms suggested as contributing factors. The purpose of this investigation was to examine whether regulatory light-chain (RLC) phosphorylation in a primary mover is associated with enhanced weightlifting performance. Nine male athletes performed 15 sets of 3 repetitions of a multijoint weightlifting activity (clean pull) at 85% 1 repetition maximum. Measures of performance, peak barbell velocity (PV), and average barbell power (AP) were determined by video analysis. Muscle biopsies were taken within 30-60 seconds of completion of the previous lifting set from the vastus lateralis before (PRE), during (MID), and after (POST) a training session. AP was significantly greater for sets 3, 4, and 5 compared with set 1, with large effect sizes (0.8-1.0). Increases in PV did not reach significance; however, the effect size increase for sets 3 and 4 versus set 1 was moderate (0.4). Relative change scores for AP and RLC phosphorylation were positively and negatively correlated at MID (r = 0.60; p = 0.05) and POST (r = -0.74; p = 0.01) exercise, respectively. These data suggest that RLC phosphorylation initially may be associated with postactivation performance enhancement during repeated multijoint exercise.

The effects of set number in stepwise load reduction resistance training on training volume and duration

Objective: This study aimed to clarify the effects of the number of loads used in stepwise load reduction training for upper body single and multi-joint resistance exercises on the training volume, duration, and the rating of perceived exertion. Design: Experimental study. Methods: Eleven young male participants performed three experimental sessions for bench press and dumbbell curls ran domly. First, they performed a high load (80% of the one-repetition maximum [1RM]) set, followed by four sets at 65%, 50%, 40%, and 30% 1RM in the five-load reduction condition (5LR), two sets at 50% and 30% 1RM in the three-load reduction condition (3LR), or one set at 30% 1RM in the two-load reduction condition (2LR) until concentric failure, with minimum intervals between the loads. The total exercise duration included exercise movement and non-exercise (setting) durations. Results: For both tests, the training volume (Load × repetitions; 1028 ± 258 kg in 5LR, 999 ± 160 kg in 3LR, and 1,003 ± 238 kg in 2LR for bench press and 226 ± 74 kg in 5LR, 200 ± 44 kg in 3LR, and 192 ± 36 kg in 2LR for dumbbell curls) and rating of perceived exertion did not differ among the conditions, whereas the total exercise and non-exercise dura tions in the five-load reduction condition were significantly longer than those in the other conditions (p < 0.01 and p < 0.001, respectively). Conclusion: The number of loads for stepwise load reduction training in upper-body single and multi-joint resistance exer cises did not affect the training volume and rating of perceived exertion. However, the training duration was shorter under the conditions with fewer loads than that under those with larger loads because of its increased non-exercise dura tion. The protocol would be more efficient if fewer loads could induce a similar adaptation.

Accuracy of Predicted Intraset Repetitions in Reserve (RIR) in Single- and Multi-Joint Resistance Exercises Among Trained and Untrained Men and Women.

We assessed the accuracy of intraset repetitions in reserve (RIR) predictions on single-joint machine-based movements of trained and untrained men and women. Participants were 27 men (M age = 22, SE = 0.6 years; M weight = 90.8, SE = 4.0kg; M height = 182.3, SE = 1.4cm; M training experience = 66, SE = 9 months) and 31 women (M age = 20, SE = 0.4 years; M weight = 67.8, SE = 2.3kg; M height = 167.6, SE = 1.1cm; M training experience = 22, SE = 4 months). In one session, participants performed a five-repetition maximum (5RM) test on biceps curl, triceps pushdown, and seated row exercises; we then estimated one repetition maximum (1RM). Participants then performed four sets of each exercise, in a randomized order, to the point of momentary muscular failure at 72.5% of 1RM. During each set, participants indicated when they first perceived 5RIR and then predicted RIR on every repetition thereafter until failure. The difference between actual repetitions performed and predicted repetitions at each intraset prediction was determined to be the RIR difference (RIRDIFF). A 3-way repeated measures ANCOVA found that a 3-way interaction was not statistically significant (p = 0.435) and no covariates of sex (p = 0.917), training experience (p = 0.462) nor experience rating RIR significantly affected RIRDIFF (p = 0.462-0.917). There were significant main effects for the proximity to failure of the prediction and the set number (p < 0.01) but not for exercise (p = 0.688). Thus, intraset RIR predictions were more accurate when closer to failure and in later sets, but sex, training experience, and experience rating RIR did not significantly influence RIR prediction accuracy on machine-based single-joint exercises.

Acute Hormonal Responses to Multi-Joint Resistance Exercises with Blood Flow Restriction.

The purpose of this study was to investigate the acute effects of multi-joint resistance exercises (MJRE) with blood flow restriction on hormonal responses. Ten men participated in the study and underwent two experimental protocols in random order: four sets (30, 15, 15, and 15 reps, respectively) of MJRE (half squat and horizontal chest press) were performed with 20% of 1RM and a rest time between sets of 30 s, combined with intermittent blood flow restriction (LI + BFR protocol); and four sets (8, 8, 8, 20 reps, respectively) of the same MJRE performed with 75% of 1RM load (HI protocol), with a 90 s rest between the first three sets and 30 s between the third to the fourth set. Blood samples were collected before (PRE), immediately after (POST), and 15 min after the performance of MJRE (POST15). A time effect was observed for growth hormone (GH) and insulin-like-growth-factor-1-binding-protein-3 (IGFPB-3), but no protocol effects or interactions between protocol and times were observed (p > 0.05). There was no effect of either protocol or time (p > 0.05) on total testosterone, free testosterone, or cortisol concentrations. However, significant (p < 0.05) increases were observed in the GH serum concentrations of 2072.73% and 2278.5%, HI, and LI + BFR protocols, respectively, from the PRE to POST15 test. In addition, there was an increase of 15.30% and 13.29% in the IGFPB-3 concentrations (p < 0.05) from PRE to POST0 times for HI and LI + BFR protocols, respectively. Furthermore, there was a decrease of −6.17% and −11.54%, p = 0.00, between the times POST0 to POST15 in the IGFPB-3 for the HI and LI + BFR protocols, respectively. It is concluded that multi-joint resistance exercises combined with intermittent blood flow restriction seemed to promote acute hormonal responses in a manner similar to traditional exercise with high loads. Future studies may investigate whether chronic use of LI + BFR with MJRE may promote muscle hypertrophy.

Hypertrophic Effects of Single- Versus Multi-Joint Exercise of the Limb Muscles: A Systematic Review and Meta-analysis

ABSTRACT We performed a systematic review and meta-analysis comparing the effects of single-joint (SJ) and multijoint (MJ) resistance exercises on muscle hypertrophy of the limb muscles. A systematic search was performed to identify randomized trials that directly compared hypertrophic changes between SJ and MJ resistance exercises, as well as combinations of the 2, in healthy adults. A total of 7 studies met inclusion criteria, comprising 10 nested comparisons. Meta-analysis indicated a trivial standardized point estimate with a relatively moderate precision for the confidence interval estimate. Subgroup analyses showed no effect on results when stratifying studies according to combined SJ + MJ versus MJ training alone, as well as under volume-equated or nonequated conditions. However, scrutiny of individual studies in conjunction with related indirect evidence collectively indicate that SJ exercise may provide the ability to preferentially hypertrophy muscular subdivisions, potentially promoting more complete muscle development. We conclude that current evidence indicates similar whole muscle hypertrophy between MJ and SJ training. There may be added benefit to combining SJ and MJ exercises for targeting individual aspects of a given muscle, although this hypothesis remains understudied. Future studies are needed to explore the effects of SJ and MJ exercises in resistance training on regional muscle hypertrophy.

Low-volume acute multi-joint resistance exercise elicits a circulating brain-derived neurotrophic factor response but not a cathepsin B response in well-trained men.

This study examined if acute multi-joint resistance exercises (RE; back squat, bench press, and deadlift) to volitional failure elicited a postexercise increase in the circulating response of biomarkers associated with neuroprotection. Thirteen males (age: 24.5 ± 3.8 years, body mass: 84.01 ± 15.44 kg, height: 173.43 ± 8.57 cm, training age: 7.1 ± 4.2 years) performed 4 sets to failure at 80% of a 1-repetition maximum on the squat, bench press, and deadlift in successive weeks. The measured biomarkers were brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), cathepsin B (CatB), and interleukin 6 (IL-6). Biomarkers were assessed immediately before and 10-min after exercise. There was a main time effect (pre-exercise: 24.00 ± 0.61 to postexercise: 27.38 ± 0.48 ng/mL; p < 0.01) for BDNF with increases in the deadlift (p = 0.01) and bench press (p = 0.01) conditions, but not in the squat condition (p = 0.21). There was a main time effect (pre-exercise: 0.87 ± 0.16 to postexercise: 2.03 ± 0.32 pg/mL; p < 0.01) for IL-6 with a significant increase in the squat (p < 0.01), but not the bench press (p = 0.88) and deadlift conditions (p = 0.24). No main time effect was observed for either CatB (p = 0.62) or IGF-1 (p = 0.56). In summary, acute multi-joint RE increases circulating BDNF. Further, this investigation is the first to report the lack of a transient change of CatB to an acute RE protocol. Novelty Low-volume RE to failure can increase BDNF. Resistance training does not confer an acute Cat B response.

Training specificity performing single-joint vs. multi-joint resistance exercises among physically active females: A randomized controlled trial.

Resistance-training of the lower limbs can be performed using exercises moving one (single-joint exercises) or several joints (multi-joint exercises). This study compared the effects of training one multi-joint exercise (leg press) or two single-joint exercises (leg extension and kickback) on dynamic and isometric strength and the transferability of dynamic strength between exercises. Fifty-three physically active women were randomized to a multi-joint (MJ) training group (age = 21.95±0.82 years, mass = 64.85±5.76 kg, height = 167.35±2.47 cm; n = 20), single-joint (SJ) training group (age = 22.56±1.66 years, mass = 64.85±5.76 kg, height = 165.94±2.84 cm; n = 18), or a control (CON) group (age = 21.27±0.68 years, mass = 68.43±4.86 kg, height = 168.63±2.84 cm; n = 15). The training groups participated in an 8-week supervised single- or multi-joint lower limb training consisting of 18 sessions. Pre- and post-training, six repetitions maximum (RM) and maximal voluntary isometric contraction in the three exercises were assessed, along with electromyography of the superficial quadriceps muscles. Improvements in all dynamic exercises were greatest after training the specific exercises (ES = 1.26–2.14, P<0.001–0.025) and all were greater in the training groups than in the CON group (ES = 1.43–3.31, P<0.001–0.021). The SJ group improved 6RM in leg extension and kickback more than leg press (ES = 1.51 and 2.04, respectively, P<0.001), whereas the MJ group improved leg press 6RM more than kickback (ES = 1.10, P = 0.002). However, leg press and leg extension strength improved similarly in the MJ group (ES = 0.54, P = 0.072). All strength and electromyographic measures remained unchanged in the CON group (ES = 0.00–0.44, P = 0.412–0.966). Improved dynamic strength in leg press, kickback and leg extension is best attained by training the specific exercises, but both training modalities can improve strength across all exercises.

Functional strength exercise and blood-flow restriction protocols: a systematic review

Objective: To assess current literature focused on the influence of functional training with blood flow restriction (BFR) on muscular adaptation in adults below the age of 65 years. Methods: A systematic literature search was performed with the following databases: PubMed, CINAHL Complete EBSCOhost, and ScienceDirect. Two researchers filtered the articles according to the criteria and quality, supported by the Consolidated Standards of Reporting Trials (CONSORT) tool. Studies were limited to those with participants with a mean age between18 and 65 years. Articles were peer-reviewed, available in English, and utilized either multi-joint resistance exercises or functional exercise as the intervention. Results: The search yielded 16 studies on uninjured, older adult, injured and athletic subjects. Regardless of the population, the studies tended to favor BFR training for improvements of strength, but this was highly dependent on cuff pressure and training load. Conclusions: Current literature suggests that BFR with functional and or multi-joint strength training is successful in improving strength, hypertrophy, function and in pain reduction. Favorable results with functional BFR included procedures using relative and well-controlled occlusion pressure. More research is necessary to understand the effect of BFR on self-reported outcomes and hypertrophy in athletic and older adults.

Could Knee Extension And Leg Press Exercises Induce Different Time Course Of Muscle Recovery?

Single- (SJ) and multiple-joint (MJ) resistance exercises are recommended for strength and hypertrophic gains. However, the levels of mechanical strain and hence muscle damage may be distinct between MJ and SJ resistance exercises. Studies comparing symptoms of muscle damage following MJ and SJ exercises are lacking. PURPOSE: This study investigated the time course of symptoms of muscle recovery after two knee extension exercises in resistance-untrained men. METHODS: Seven men (25 ± 4 yrs) were randomly assigned to perform a unilateral MJ multi-joint resistance exercise (i.e. leg press, LP) and a unilateral single-joint resistance exercise (i.e. seated knee extension, KE) with the contralateral limb. Participants performed 8 sets of 10 repetition maximum of both exercises with 2 min rest between sets. Muscle edema (ME), peak torque (PT), 1-legged countermovement (CMJ), and muscle soreness (MS) were measured pre, post, 24, 48, 72 and 96h following exercise. RESULTS: ME of the rectus femoris returned to baseline at 48h after LP exercise, and at 24h after the KE exercise. ME of the vastus lateralis recovered at 24h after both exercises. PT recovered at 24h, and there was no difference between both exercises (p>0.05). CMJ returned to the baseline values 72h after the LP exercise, and 24h after the KE exercise. Muscle soreness of the rectus femoris was greater at 48h after KE when compared to LP exercise. There was no difference between exercises in the magnitude of MS response in vastus lateralis (p>0.05). CONCLUSIONS: Resistance-untrained men experience different muscle recovery following LP and KE exercises. The MJ condition was more stressful for knee extensors muscles than SJ, taking more time to recover from muscle damage.

A single multi-joint high-intensity resistance exercise involving large muscle groups elicits post-exercise hypotension in normotensive-trained women: a crossover trial

The aim of this study was to investigate whether only 1 multi-joint resistance exercise involving large muscle groups can elicit post-exercise hypotension (PEH). A randomized crossover trial was conducted with 13 normotensive-trained women (21.8 ± 2.1 years; 23.5 ± 3.1 kg/m2; blood pressure 100.4 ± 4.9/58.6 ± 5.6 mmHg). They were submitted randomly into two sessions: (a) a single multi-joint resistance exercise session (3 sets of 20 repetitions at 80% of 20 repetitions maximum performed on double-leg press machine) and (b) control session (15 min of resting in a seated position). Blood pressure (BP) was measured before and at 20, 40, and 60 min following the control and resistance exercise sessions. It was observed a reduction in systolic BP at 40 min (4.8 ± 4.6 mmHg) and 60 min (6.3 ± 4.3 mmHg) post-exercise with a moderate magnitude (d ≥ 0.79, p 0.05). A single multi-joint high-intensity resistance exercise involving large muscle groups and performed within a very low time commitment elicited systolic PEH in normotensive-trained women.

Single vs. Multi-Joint Resistance Exercises: Effects on Muscle Strength and Hypertrophy

Background:Some authors suggest that single joint (SJ) exercises promote greater muscle hypertrophy because they are easier to be learned and therefore have less reliance on neural factors. On the other hand, some authors recommend an emphasis on multi-joint (MJ) exercises for maximizing muscle strength, assuming that MJ exercises are more effective than SJ exercises because they enable a greater magnitude of weight to be lifted.Objectives:The present study aimed to compare the effects of MJ vs. SJ exercises on muscle size and strength gains in untrained young men.Patients and Methods:Twenty-nine young men, without prior resistance training experience, were randomly divided into two groups. One group performed (n = 14) only MJ exercises involving the elbow flexors (lat. pull downs), while the other (n = 15) trained the elbow flexors muscles using only SJ exercises (biceps curls). Both groups trained twice a week for a period of ten weeks. The volunteers were evaluated for peak torque of elbow flexors (PT) in an isokinetic dynamometer and for muscle thickness (MT) by ultrasonography.Results:There were significant increases in MT of 6.10% and 5.83% for MJ and SJ, respectively; and there were also significant increases in PT for MJ (10.40%) and SJ (11.87%). However, the results showed no difference between groups pre or post training for MT or PT.Conclusions:In conclusion, the results of the present study suggest that MJ and SJ exercises are equally effective for promoting increases in upper body muscle strength and size in untrained men. Therefore, the selection between SJ and MJ exercises should be based on individual and practical aspects, such as, equipment availability, movement specificity, individual preferences and time commitment.

Nonuniform Muscle Hypertrophy

Muscle hypertrophy in response to resistance training has been reported to occur nonuniformly along the length of the muscle. The purpose of the present study was to examine whether the regional difference in muscle hypertrophy induced by a training intervention corresponds to the regional difference in muscle activation in the training session. Twelve young men participated in a training intervention program for the elbow extensors with a multijoint resistance exercise for 12 wk (3 d · wk(-1)). Before and after the intervention, cross-sectional areas of the triceps brachii along its length were measured with magnetic resonance images. A series of transverse relaxation time (T2)-weighted magnetic resonance images was recorded before and immediately after the first session of training intervention. The T2 was calculated for each pixel within the triceps brachii. In the images recorded after the session, the number of pixels with a T2 greater than the threshold (mean + 1 SD of T2 before the session) was expressed as the ratio to the whole number of pixels within the muscle and used as an index of muscle activation (percent activated area). The percent activated area of the triceps brachii in the first session was significantly higher in the middle regions than that in the most proximal region. Similarly, the relative change in cross-sectional area induced by the training intervention was also significantly greater in the middle regions than the most proximal region. The results suggest that nonuniform muscle hypertrophy after training intervention is due to the region-specific muscle activation during the training session.

Effect of Squat Depth and Barbell Load on Relative Muscular Effort in Squatting

Resistance training is used to develop muscular strength and hypertrophy. Large muscle forces, in relation to the muscle's maximum force-generating ability, are required to elicit these adaptations. Previous biomechanical analyses of multi-joint resistance exercises provide estimates of muscle force but not relative muscular effort (RME). The purpose of this investigation was to determine the RME during the squat exercise. Specifically, the effects of barbell load and squat depth on hip extensor, knee extensor, and ankle plantar flexor RME were examined. Ten strength-trained women performed squats (50-90% 1 repetition maximum) in a motion analysis laboratory to determine hip extensor, knee extensor, and ankle plantar flexor net joint moment (NJM). Maximum isometric strength in relation to joint angle for these muscle groups was also determined. Relative muscular effect was determined as the ratio of NJM to maximum voluntary torque matched for joint angle. Barbell load and squat depth had significant interaction effects on hip extensor, knee extensor, and ankle plantar flexor RME (p < 0.05). Knee extensor RME increased with greater squat depth but not barbell load, whereas the opposite was found for the ankle plantar flexors. Both greater squat depth and barbell load increased hip extensor RME. These data suggest that training for the knee extensors can be performed with low relative intensities but require a deep squat depth. Heavier barbell loads are required to train the hip extensors and ankle plantar flexors. In designing resistance training programs with multi-joint exercises, how external factors influence RME of different muscle groups should be considered to meet training objectives.

The Effect of Load Reductions on Repetition Performance for Commonly Performed Multijoint Resistance Exercises

The purpose of this study was to compare 4 different loading schemes for the free weight bench press, wide grip front lat pull-down, and free weight back squat to determine the extent of progressive load reductions necessary to maintain repetition performance. Thirty-two recreationally trained women (age = 29.34 ± 4.58 years, body mass = 59.61 ± 4.72 kg, height = 162.06 ± 4.04 cm) performed 4 resistance exercise sessions that involved 3 sets of the free weight bench press, wide grip front lat pull-down, and free weight back squat, performed in this exercise order during all 4 sessions. Each of the 4 sessions was conducted under different randomly ordered loading schemes, including (a) a constant 10 repetition maximum (RM) load for all 3 sets and for all 3 exercises, (b) a 5% reduction after the first and second sets for all the 3 exercises, (c) a 10% reduction after the first and second sets for all the 3 exercises, and (d) a 15% reduction after the first and second sets for all the 3 exercises. The results indicated that for the wide grip front lat pull-down and free weight back squat, a 10% load reduction was necessary after the first and second sets to accomplish 10 repetitions on all the 3 sets. For the free weight bench press, a load reduction between 10 and 15% was necessary; specifically, a 10% reduction was insufficient and a 15% reduction was excessive, as evidenced by significantly >10 repetitions on the second and third sets for this exercise (p ≤ 0.05). In conclusion, the results of this study indicate that a resistance training prescription that involves 1-minute rest intervals between multiple 10RM sets does require load reductions to maintain repetition performance. Practitioners might apply these results by considering an approximate 10% load reduction after the first and second sets for the exercises examined, when training women of similar characteristics as in this study.

High-power resistance exercise induces MAPK phosphorylation in weightlifting trained men

Power is critical to muscle performance, specifically in athletic populations. Mitogen-activated protein kinase (MAPK) pathways (extracellular signal-regulated protein kinase (ERK 1/2), p38, and c-Jun NH(2)-terminal kinase (JNK)) are intracellular signal transduction mechanisms that partially regulate exercise-induced skeletal muscle alterations. These pathways are highly responsive to exercise, but their reaction to high power, multi-joint resistance exercise is yet to be examined. Nine weightlifting-trained men performed 15 sets of three repetitions of a dynamic clean pull exercise at 85% of their one repetition maximum. Vastus lateralis biopsies were obtained prior to (pre) and after the 8th (mid) and 15th set (post) of exercise. Three subjects returned to serve as non-exercising controls for a similar sequence of biopsies (CON). The ratio of phosphorylated MAPK to total MAPK increased significantly for p38 (3.0 fold, p<0.05) and JNK (2.4 fold, p<0.05) by the mid biopsy. ERK 1/2 phosphorylation followed a similar trend (2.3 fold) (p= 0.052). The ratio of phosphorylation to total MAPK did not differ from mid to post biopsy. None of the pathways were phosphorylated above resting in the CON condition (p>0.05), and thus the biopsy procedure itself did not account for the entire increase in MAPK phosphorylation during EX. These data indicate MAPK pathways are activated early and remain elevated throughout the duration of high power resistance exercise. These findings help describe the mechanisms partially responsible for chronic adaptations in response to high intensity, high power resistance training in humans.

Effects Of Caffeine On Resistance Exercise Performance, Mood, Heart Rate, And Rating Of Perceived Exertion

Previous studies examined acute effects of caffeine on muscular strength and endurance. However, limited research exists on the influence of caffeine on performance and perception over the course of an entire resistance exercise bout. PURPOSE: Therefore, we investigated the effects of caffeine on resistance exercise performance, mood, heart rate (HR), and rating of perceived exertion (RPE). METHODS: Nine resistance trained males completed two separate trials of resistance exercise after ingesting caffeine (10 mg/kg of BW) or placebo. During each trial, subjects performed four major multi-joint resistance exercises (2 sets of 10 repetitions followed by 1 set to exhaustion) with two minutes rest between sets. Investigators measured RPE, HR, and Profile of Mood States (POMS) before, during, and after each trial. RESULTS: No significant differences existed between conditions in total repetitions during the final set of each exercise and RPE. HR during caffeine trials significantly exceeded placebo at several time points during the first two exercises. Significant main effects indicated that Tension-Anxiety (+ 45%), Depression-Dejection (+ 81%), Anger-Hostility (+ 68%), and Total Mood Disturbance (+ 62 %) in the caffeine condition significantly exceeded the placebo condition. CONCLUSION: These results suggest that pre-workout caffeine ingestion fails to alter performance and RPE while influencing mood characteristics and HR during a resistance exercise bout.

Voluntary Increase in Latissimus Dorsi Muscle Activity During the Lat Pull-Down Following Expert Instruction

It has been observed anecdotally that while performing the multijoint lat pull-down exercise, novice strength trainers often rely on the elbow flexors to complete the movement rather than fully utilizing the relevant back muscles such as the latissimus dorsi (LD) and teres major (TM). The primary aim of the study was to determine whether specific technique instruction could result in a voluntary increase in LD and TM electromyographic (EMG) activity with a concurrent decrease in the activity of the biceps brachii (BB) during the front wide-grip lat pull-down exercise. Eight women with little or no background in strength training were asked to perform lat pull-down exercise with only basic instruction, performing 2 sets of 3 repetitions at 30% max. After a brief rest, subjects then performed the same 2 sets of 3 repetitions following verbal technique instruction on how to emphasize the latissimus while de-emphasizing the biceps. EMG activity of the LD, TM, and BB were recorded, converted to root mean square, and normalized to the maximum isometric EMG (NrmsEMG). A significant increase was seen in Nrms EMG in the LD (p = 0.005) from the average of preinstruction NrmsEMG to the average of postinstruction NrmsEMG. No significant differences were observed between pre- and postinstruction muscle activity in the BB or TM. The results show that untrained individuals can voluntarily increase the activity of a specified muscle group during the performance of a multijoint resistance exercise, but the increase probably does not represent "isolation" of the muscle group through voluntary reduction of activity in complementary agonist muscles.

Pro-antioxidant ratio in healthy men exposed to muscle-damaging resistance exercise

The purpose of this study was to compare the pro-antioxidant status in healthy men exposed to muscle-damaging resistance exercise, and to investigate the practical application of Loverro's coefficient (P/A ratio) to evaluate the presence of oxidative stress. Twenty-eight healthy men were assigned to two groups performed multi-joint (M) or single-joint (S) resistance exercise. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) as well as the concentration of lipid peroxidation products (TBARS) in blood were evaluated. The P/A ratio was calculated from the mean values of erythrocyte TBARS, SOD, CAT and GPx. Creatine kinase (CK) activity was used as a marker of muscle damage. The applied resistance exercises triggered off the changes in pro-antioxidant ratio towards peroxidation which was proved by significant increase in erythrocyte TBARS concentration in M (+25%) and S (+27%) groups. Plasma TBARS increased only after multi-joint resistance exercise and correlated with erythrocyte P/A ratio (r = 0.536, P < 0.01). The multi-joint exercise caused decrease in SOD activity by 28% whereas the single-joint resistance exercise elevated enzyme activity by 20%. Activities of the other antioxidant enzymes changed simultaneously i.e. CAT activity increased by 14%-16% immediately after exercise, and GPx activity declined by 18%-34% during recovery in M and S groups. Even though, all erythrocyte parameters significantly changed following multi-joint and single-joint resistance exercises, the assessment of pro-antioxidant ratio showed the considerable increase in P/A only in M group. In summary, an analysis of pro- and antioxidant parameters showed significant changes in response to muscle-damaging exercise and demonstrated the practical application of P/A ratio to evaluate the risk of oxidative stress in athletes.

ACUTE MUSCLE SORENESS RESPONSES TO PLYOMETRIC AND MULTIJOINT WEIGHT LIFTING EXERCISES ARE RELATED TO INTENSITY.

Plyometric (P) and resistance exercise are used widely in athletic training. However, the effects of multijoint weight lifting exercises (MJ) on DOMS development when combined to plyometrics is still unclear. In addition, there is limited information concerning the influence of exercise intensity of MJ on DOMS. PURPOSE To determine the acute effects of MJ, of either moderate or high intensity, and P on development of DOMS and related indices. METHODS 32 college aged students were randomly assigned to one of four groups (n = 8/group): control (C), plyometrics (P), combination of P and MJ exercises (squat and hang cleans) of moderate (70% of 1-RM, MMJP) or high intensity (95% of 1-RM, HMJP). DOMS, CK and LDH activity, IL-1b, IL-6, cortisol and testosterone conentrations in plasma, were measured pre, immediately post as well as 24, 48, 72 and 96 hours post exercise. Data were analyzed using MANOVA repeated measures. RESULTS HMJP and MMJP elicited a higher increase in DOMS (8.2±2.1 and 7.8±1 .8) compared to P (6.1±2.2) at peak (48h). CK and LDH peaked at 24h in HMJP (524±56.7 U/L and 529.8±44.2 U/L) and MMJP (438.7±67.5 U/L and 567.3±85.6 U/L) and at 48h in P (138.3±35.8 U/L and 254.9±41.6 U/L). Testosterone and cortisol peaked at 48h in HMJP (11.6±2.3 ng/ml and 224.5±55.8 ng/ml), MMJP (9.9±2.1 ng/ml and 176.8±46.2 ng/ml) and P (9.9±1.8 ng/ml and 164.5±39.4 ng/ml). IL-1b and 6 peaked at 24h in HMJP (110,4±23.8 pg/ml and 18.2±4.4 pg/ml), MMJP (75.2±24.1 pg/ml and 12.7±3.1 pg/ml) and P (68.4±19.5 pg/ml and 9.6±2.6 pg/ml). HMJP elicited significantly greater responses in all variables examined, except DOMS, than the other exercise groups (DOMS development was the same in HMJP and MMJP) CONCLUSION Plyometric and multijoint resistance exercises seem to elicit a significant DOMS response one or two days post exercise. However, this response was greater when high intensity multijoint exercises were utilized. Biochemical and DOMS responses followed a different time course of development.