The influence of volume of exercise on early adaptations to strength training

The purpose of this investigation was to compare the effects of single-set strength training and 3-set strength training during the early phase of adaptation in 18 untrained male subjects (age, 20-30 years). After initial testing, subjects were randomly assigned to either the 3L-1U group (n = 8), which trained 3 sets in leg exercises and 1 set in upper-body exercises, or the 1L-3U group (n = 10), which trained 1 set in leg exercises and 3 sets in upper-body exercises. Testing was conducted at the beginning and at the end of the study and consisted of 2 maximal isometric tests (knee extension and bench press) and 6 maximal dynamic tests (1 repetition maximum [1RM] tests). Subjects trained 3 days per week for 6 weeks. After warm-up, subjects performed 3 leg exercises and 4 upper-body exercises. In both groups, each set consisted of 7 repetitions (reps) with the load supposed to induce muscular failure after the seventh rep (7RM load). After 6 weeks of training, 1RM performance in all training exercises was significantly increased (10-26%, p < 0.01) in both groups. The relative increase in 1RM load in the 3 leg exercises was significantly greater in the 3L-1U group than in the 1L-3U group (21% vs. 14%, p = 0.01). However, the relative increase in 1RM load in the 3 upper-body exercises was similar in the 3L-1U group (16%) and the 1L-3U group (14%). These results show a superior adaptation to 3-set strength training, compared with 1-set strength training, in leg exercises but not in upper-body exercises during the early phase of adaptation.     

1-Set vs. 3-set resistance training: a crossover study

This crossover study was conducted to investigate the effects of a 1-set and 3-set strength training program. The subjects were untrained men and women who were randomly signed into 1 of 3 groups: 10 subjects trained during the first 9 weeks (training period 1) with 1 set and 8-12 repetitions per set. After the break (9 weeks), they trained with 3 sets and 8-12 repetitions in training period 2. Twelve subjects started with the 3-set program and continued with the 1-set regime after the break. The control group (n = 7) did not train. The subjects were tested on 1 repetition maximum (1RM) for the biceps curl, leg press (unilateral: left and right), and bench press. Analysis of the data was done in a sampled manner for each strength training program (1-set and 3-set). The 1-set (n = 22) and 3-set (n = 22) programs led to significantly (p < 0.05) improved 1RM performances in every exercise. The relative improvements (%) for the 1RM were significantly higher during the 3-set program for the biceps curl and the bench press compared with the 1-set program. The control group exhibited no changes in any of the tested parameters over the course of this study. The design of this study allowed insight into the effects of different strength training volume without any genetical variations. The same subjects improved their 1RM during the 3-set program by 2.3 kg (biceps curl; corresponding effect size = 0.24), 8.9 kg (leg press right; 0.30), 10.9 kg (leg press left; 0.28), and 2.5 kg (bench press; 0.09) more than during the 1-set program. Depending on the goals of each trainee, these differences between the effects of different strength training volumes indicate that it may be worth spending more time on working out with a 3-set strength training regime.     

Hypertrophic response to unilateral concentric isokinetic resistance training.

The purposes of this study were to 1) determine the effect of concentric isokinetic training on strength and cross-sectional area (CSA) of selected extensor and flexor muscles of the forearm and leg, 2) examine the potential for preferential hypertrophy of individual muscles within a muscle group, 3) identify the location (proximal, middle, or distal level) of hypertrophy within an individual muscle, and 4) determine the effect of unilateral concentric isokinetic training on strength and hypertrophy of the contralateral limbs. Thirteen untrained male college students [mean age 25.1 +/- 6.1 (SD) yr] volunteered to perform six sets of 10 repetitions of extension and flexion of the nondominant limbs three times per week for 8 wk, using a Cybex II isokinetic dynamometer. Pretraining and posttraining peak torque and muscle CSA measurements for both the dominant and nondominant limbs were determined utilizing a Cybex II isokinetic dynamometer and magnetic resonance imaging scanner, respectively. The results indicated significant (P less than 0.0008) hypertrophy in all trained muscle groups as well as preferential hypertrophy of individual muscles and at specific levels. None of the muscles of the contralateral limbs increased significantly in CSA. In addition, significant (P less than 0.0008) increases in peak torque occurred for trained forearm extension and flexion as well as trained leg flexion. There were no significant increases in peak torque, however, for trained leg extension or for any movement in the contralateral limbs. These data suggest that concentric isokinetic training results in significant strength and hypertrophic responses in the trained limbs.     

Effects of linear vs. daily undulatory periodized resistance training on maximal and submaximal strength gains

The objective of this study was to verify the effect of 2 periodized resistance training (RT) methods on the evolution of 1-repetition maximum (1RM) and 8RM loads. Twenty resistance trained men were randomly assigned to 2 training groups: linear periodization (LP) group and daily undulating periodization (DUP) group. The subjects were tested at baseline and after 12 weeks for 1RM and 8RM loads in leg press (LEG) and bench press (BP) exercises. The training program was performed in alternated sessions for upper (session A: chest, shoulder and triceps) and lower body (session B: leg, back and biceps). The 12-week periodized training was applied only in the tested exercises, and in the other exercises, 3 sets of 6-8RM were performed. Both groups exhibited significant increases in 1RM loads on LEG and BP, but no statistically significant difference between groups was observed. The same occurred in 8RM loads on LEG and BP. However, DUP group presented superior effect size (ES) in 1RM and 8RM loads for LEG and BP exercises when compared to the LP group. In conclusion, periodized RT can be an efficient method for increasing the strength and muscular endurance in trained individuals. Although there was no statistically significant difference between periodization models, DUP promoted superior ES gains in muscular maximal and submaximal strength.     

Early phase strength development: a four-week training comparison of different programs

The purpose of this study was to explore the effects of various exercise sequences in the early weeks of a strength training program. Forty-two untrained men were randomly assigned to one of 4 training regimens, which were differentiated by the order in which the exercises were performed, and trained 3 days per week for 4 weeks. Three regimens were multiple-set protocols (alternating, blocked, and semiblocked), and the fourth was a single-set protocol. The exercises were arm curls, lateral raises, and triceps extensions. Results showed that the blocked group improved significantly more on the arm curl exercise than the single-set group. No other group comparisons were significant. This finding indicates that a blocked multiple-set regimen is superior to a single-set regimen for certain upper-body exercises in the early stages of strength training.     

Muscle adaptations to plyometric vs. resistance training in untrained young men

The purpose of this study was to compare changes in muscle strength, power, and morphology induced by conventional strength training vs. plyometric training of equal time and effort requirements. Young, untrained men performed 12 weeks of progressive conventional resistance training (CRT, n = 8) or plyometric training (PT, n = 7). Tests before and after training included one-repetition maximum (1 RM) incline leg press, 3 RM knee extension, and 1 RM knee flexion, countermovement jumping (CMJ), and ballistic incline leg press. Also, before and after training, magnetic resonance imaging scanning was performed for the thigh, and a muscle biopsy was sampled from the vastus lateralis muscle. Muscle strength increased by approximately 20-30% (1-3 RM tests) (p < 0.001), with CRT showing 50% greater improvement in hamstring strength than PT (p < 0.01). Plyometric training increased maximum CMJ height (10%) and maximal power (Pmax; 9%) during CMJ (p < 0.01) and Pmax in ballistic leg press (17%) (p < 0.001). This was far greater than for CRT (p < 0.01), which only increased Pmax during the ballistic leg press (4%) (p < 0.05). Quadriceps, hamstring, and adductor whole-muscle cross-sectional area (CSA) increased equally (7-10%) with CRT and PT (p < 0.001). For fiber CSA analysis, some of the biopsies had to be omitted. Type I and IIa fiber CSA increased in CRT (n = 4) by 32 and 49%, respectively (p < 0.05), whereas no significant changes occurred for PT (n = 5). Myosin heavy-chain IIX content decreased from 11 to 6%, with no difference between CRT and PT. In conclusion, gross muscle size increased both by PT and CRT, whereas only CRT seemed to increase muscle fiber CSA. Gains in maximal muscle strength were essentially similar between groups, whereas muscle power increased almost exclusively with PT training.     

A comparison of periodization models during nine weeks with equated volume and intensity for strength

The purpose of the present investigation was to determine if significant differences exist among 3 different periodization programs in eliciting changes in strength. Twenty-eight recreationally trained college-aged volunteers (mean +/- SD; 22.29 +/- 3.98) of both genders were tested for bench press, leg press, body fat percentage, chest circumference, and thigh circumference during initial testing. After initial testing, subjects were randomly assigned to 1 of 3 training groups: (a) linear periodization (n = 9), (b) daily undulating periodization (n = 10), or (c) weekly undulating periodization (n = 9). The training regimen for each group consisted of a 9-week, 3-day-per-week program. Training loads were assigned as heavy (90%, 4 repetition maximum [4RM]), medium (85%, 6RM), or light (80%, 8RM) for bench press and leg press exercises. Subjects were familiarized with the CR-10 rated perceived exertion scale and instructed to achieve an 8 or 9 on the final repetition of each set for all other exercises. Subjects were then retested after 4 weeks of training. Training loads were then adjusted according to the new 1RM. Subjects were then retested after 5 more weeks of exercise. For all subjects, significant (p < 0.05) increases in bench press and leg press strength were demonstrated at all time points (T1-T3). No significant differences (p > 0.05) were observed between groups for bench press, leg press, body fat percentage, chest circumference, or thigh circumference at all time points. These results indicate that no separation based on periodization model is seen in early-phase training.     

Effects of leucine and whey protein supplementation during eight weeks of unilateral resistance training

The purpose of this study was to determine the effects of resistance training in combination with a leucine and whey protein supplement or a carbohydrate placebo on strength and muscle cross-sectional area (CSA). Thirty-three men (mean age +/- SD = 22.4 +/- 2.4 years) were assigned to 1 of 3 groups: (1) supplementation group (SUPP), (2) placebo group (PL), or (3) control group (CON). The SUPP and PL performed unilateral training of the leg extensor muscles with the nondominant limb for 8 weeks. The strength of each limb, muscle CSA of the quadriceps femoris (QF), and body composition were assessed pretraining and posttraining. The results indicated significant increases in strength for both limbs in the SUPP but only the trained limb in the PL. The increase in strength for the trained limb of the SUPP was greater than that for the trained limb of the PL. There was no significant increase in strength for either limb in the CON. There were significant increases in the CSA of all muscles of the QF of the trained limb for the SUPP and PL, and of the vastus lateralis of the untrained limb for the SUPP. The increases in QF CSA did not differ between the SUPP and PL. No significant CSA changes were found for either limb in the CON. There were no significant changes in body composition for the SUPP, PL, or CON. The current findings suggest that leucine and whey protein supplementation may provide an ergogenic effect which enhances the acquisition of strength beyond that achieved with resistance training and a carbohydrate placebo.     

Three sets of weight training superior to 1 set with equal intensity for eliciting strength

The purpose of this study was to compare single and multiple sets of weight training for strength gains in recreationally trained individuals. Sixteen men (age = 21 +/- 2.0) were randomly assigned to 1 set (S-1; n = 8) or 3 set (S-3; n = 8) groups and trained 3 days per week for 12 weeks. One repetition maximum (1RM) was recorded for bench press and leg press at pre-, mid-, and posttest. Subjects trained according to daily undulating periodization (DUP), involving the bench press and leg press exercises between 4RM and 8RM. Training intensity was equated for both groups. Analysis of variance with repeated measures revealed statistically significant differences favoring S-3 in the leg press (p < 0.05, effect size [ES] = 6.5) and differences approaching significance in the bench press (p = 0.07, ES = 2.3). The results demonstrate that for recreationally trained individuals using DUP training, 3 sets of training are superior to 1 set for eliciting maximal strength gains.     

The effectiveness of traditional and sling exercise strength training in women

Strength training often combines closed-kinetic-chain exercises (CKCEs) and open kinetic-chain exercises (OKCEs). The CKCE may be more effective for improving performance in lower-body training. Recently, we reported upper-body CKCE (using a commercially available system of ropes and slings, Redcord AS, Staubo, Norway) was as effective as OKCE training for strength gains and that CKCE was more effective than OKCE for improving throwing performance. To our knowledge the effectiveness of a strength training program that uses exclusively CKCE is unknown. In this study, we examined the effectiveness of CKCE vs. OKCE strength training programs in women enrolled in an introductory strength training program. Twenty-six participants were randomized to OKCE (traditional exercises) or CKCE (sling-based exercises). Participants completed 6 sets per week for 13 weeks. Pre and posttraining evaluations included the following: 1 repetition maximum (1RM) leg and bench press; sling exercise push-ups; isokinetic dynamometry; lateral step-down test; and the Star Excursion Balance Test. Both groups significantly improved bench press (by an average of 4-6 kg) and leg press (by an average of 23-35 kg) (p < 0.001). There was a significant group × time interaction (p < 0.001) for sling exercise push-ups (OKCE pre = 5.5 ± 8.6, OKCE post = 6.1 ± 8.2, CKCE pre = 6.8 ± 6.0, CKCE post = 16.9 ± 6.6). Isokinetic measures of knee extension, knee flexion, shoulder internal rotation, and shoulder external rotation increased (improvements ranged from 2.7 to 27.7%), with no group differences. Both OKCE and CKCE strength training elicited similar changes in balance. We conclude that CKCE training is equally as effective as OKCE training during the initial phases of a strength training program in women. The fact that only CKCE improved sling exercise push-ups supports previous findings suggesting functional superiority of CKCE.     

Effect of short-term equal-volume resistance training with different workout frequency on muscle mass and strength in untrained men and women

Changes in muscle mass and strength will vary, depending on the volume and frequency of training. The purpose of this study was to determine the effect of short-term equal-volume resistance training with different workout frequency on lean tissue mass and muscle strength. Twenty-nine untrained volunteers (27-58 years; 23 women, 6 men) were assigned randomly to 1 of 2 groups: group 1 (n = 15; 12 women, 3 men) trained 2 times per week and performed 3 sets of 10 repetitions to fatigue for 9 exercises, group 2 (n = 14; 11 women, 3 men) trained 3 times per week and performed 2 sets of 10 repetitions to fatigue for 9 exercises. Prior to and following training, whole-body lean tissue mass (dual energy x-ray absorptiometry) and strength (1 repetition maximum squat and bench press) were measured. Both groups increased lean tissue mass (2.2%), squat strength (28%), and bench press strength (22-30%) with training (p < 0.05), with no other differences. These results suggest that the volume of resistance training may be more important than frequency in developing muscle mass and strength in men and women initiating a resistance training program.     

Effects of 8-week in-season upper and lower limb heavy resistance training on the peak power, throwing velocity, and sprint performance of elite male handball players

The aims of this study were to test the potential of in-season heavy upper and lower limb strength training to enhance peak power output (Wpeak), vertical jump, and handball related field performance in elite male handball players who were apparently already well trained, and to assess any adverse effects on sprint velocity. Twenty-four competitors were divided randomly between a heavy resistance (HR) group (age 20 ± 0.7 years) and a control group (C; age 20 ± 0.1 years). Resistance training sessions were performed twice a week for 8 weeks. Performance was assessed before and after conditioning. Peak power (W(peak)) was determined by cycle ergometer; vertical squat jump (SJ) and countermovement jump (CMJ); video analyses assessed velocities during the first step (V(1S)), the first 5 m (V(5m)), and between 25 and 30 m (V(peak)) of a 30-m sprint. Upper limb bench press and pull-over exercises and lower limb back half squats were performed to 1-repetition maximum (1RM). Upper limb, leg, and thigh muscle volumes and mean thigh cross-sectional area (CSA) were assessed by anthropometry. W(peak) (W) for both limbs (p < 0.001), vertical jump height (p < 0.01 for both SJ and CMJ), 1RM (p < 0.001 for both upper and lower limbs) and sprint velocities (p < 0.01 for V(1S) and V(5m); p < 0.001 for V(peak)) improved in the HR group. Upper body, leg, and thigh muscle volumes and thigh CSA also increased significantly after strength training. We conclude that in-season biweekly heavy back half-squat, pull-over, and bench-press exercises can be commended to elite male handball players as improving many measures of handball-related performance without adverse effects upon speed of movement.     

Acute effect of two aerobic exercise modes on maximum strength and strength endurance

The purpose of this study was to evaluate the effects of 2 modes of aerobic exercise (continuous or intermittent) on maximum strength (1 repetition maximum, 1RM) and strength endurance (maximum repetitions at 80% of 1RM) for lower- and upper-body exercises to test the acute hypothesis in concurrent training (CT) interference. Eight physically active men (age: 26.9 +/- 4.2 years; body mass: 82.1 +/- 7.5 kg; height: 178.9 +/- 6.0 cm) were submitted to: (a) a graded exercise test to determine V(.-)O2max (39.26 +/- 6.95 ml x kg(-1) x min(-1)) and anaerobic threshold velocity (3.5 mmol x L(-1)) (9.3 +/- 1.27 km x h(-1)); (b) strength tests in a rested state (control); and (c) 4 experimental sessions, at least 7 days apart. The experimental sessions consisted of a 5-kilometer run on a treadmill continuously (90% of the anaerobic threshold velocity) or intermittently (1:1 minute at V(.-)O2max). Ten minutes after the aerobic exercise, either a maximum strength or a strength endurance test was performed (leg press and bench press exercises). The order of aerobic and strength exercises followed a William's square distribution to avoid carryover effects. Results showed that only the intermittent aerobic exercise produced an acute interference effect on leg strength endurance, decreasing significantly (p < 0.05) the number of repetitions from 10.8 +/- 2.5 to 8.1 +/- 2.2. Maximum strength was not affected by the aerobic exercise mode. In conclusion, the acute interference hypothesis in concurrent training seems to occur when both aerobic and strength exercises produce significant peripheral fatigue in the same muscle group.     

Specific effects of eccentric and concentric training on muscle strength and morphology in humans

The purpose of this study was to compare pure eccentric and concentric isokinetic training with respect to their possible specificity in the adaptation of strength and morphology of the knee extensor muscles. Ten moderately trained male physical education students were divided into groups undertaking eccentric (ETG) and concentric (CTG) training. They performed 10 weeks of maximal isokinetic (90 degrees x s(-1)) training of the left leg, 4x10 repetitions - three times a week, followed by a second 10-week period of similar training of the right-leg. Mean eccentric and concentric peak torques increased by 18% and 2% for ETG and by 10% and 14% for CTG, respectively. The highest increase in peak torque occurred in the eccentric 90 degrees x s(-1) test for ETG (35%) whereas in CTG strength gains ranged 8%-15% at velocities equal or lower than the training velocity. Significant increases in strength were observed in the untrained contra-lateral leg only at the velocity and mode used in ipsilateral training. Cross-sectional area of the quadriceps muscle increased 3%-4% with training in both groups, reaching statistical significance only in ETG. No major changes in muscle fibre composition or areas were detected in biopsies from the vastus lateralis muscle for either leg or training group. In conclusion, effects of eccentric training on muscle strength appeared to be more mode and speed specific than corresponding concentric training. Only minor adaptations in gross muscle morphology indicated that other factors, such as changes in neural activation patterns, were causing the specific training-induced gains in muscle strength.     

The effects of short-term unilateral and bilateral lower-body resistance training on measures of strength and power

The purpose of this study was to compare the effects of short-term unilateral resistance training (UL) and bilateral resistance training (BL) with free weights on several tests of unilateral and bilateral lower-body strength and power in men and women. Thirty-eight untrained men and women (mean body mass 78.3 +/- 21.47 kg; age 20.74 +/- 2.6 years) completed the study. The groups trained 2 days per week for 8 weeks with free weights and 2 days per week for 5 of the 8 weeks with plyometric drills. The resistance-training program consisted of a progression from 3 sets of 15 repetitions at 50% of the subject's predicted 1 repetition maximum (1RM) to 6 sets of 5 repetitions at 87% 1RM. Training volume and intensity were equal for each group. The free-weight squat was used to measure unilateral and bilateral strength. Power was measured by the Magaria-Kalamen stair-climb test and the unilateral and bilateral vertical jump test. Analysis of covariance was used to analyze differences between men and women and the interaction of group and gender. Pretest scores were used as the covariate. The UL group improved more than the BL group on the unilateral vertical jump height (p = 0.001) and relative power (p = 0.013). After adjusting for pretest differences, the improved scores on all tests, except for the unilateral squat, were similar between the men and the women. No significant interactions on all tests were found for the men or women comparison between training groups. These results indicate that UL and BL are equally effective for early phase improvement of unilateral and bilateral leg strength and power in untrained men and women.     

Interaction between concurrent strength and endurance training

To assess the effects of concurrent strength (S) and endurance (E) training on S and E development, one group (4 young men and 4 young women) trained one leg for S and the other leg for S and E (S+E). A second group (4 men, 4 women) trained one leg for E and the other leg for E and S (E+S). E training consisted of five 3-min bouts on a cycle ergometer at a power output corresponding to that requiring 90-100% of oxygen uptake during maximal exercise (VO2 max). S training consisted of six sets of 15-20 repetitions with the heaviest possible weight on a leg press (combined hip and knee extension) weight machine. Training was done 3 days/wk for 22 wk. Needle biopsy samples from vastus lateralis were taken before and after training and were examined for histochemical, biochemical, and ultrastructural adaptations. The nominal S and E training programs were "hybrids", having more similarities as training stimuli than differences; thus S made increases (P less than 0.05) similar to those of S+E in E-related measures of VO2max (S, S+E: 8%, 8%), repetitions with the pretraining maximal single leg press lift [1 repetition maximum (RM)] (27%, 24%), and percent of slow-twitch fibers (15%, 8%); and S made significant, although smaller, increases in repetitions with 80% 1 RM (81%, 152%) and citrate synthase (CS) activity (22%, 51%). Similarly, E increased knee extensor area [computed tomography (CT) scans] as much as E+S (14%, 21%) and made significant, although smaller, increases in leg press 1 RM (20%, 34%) and thigh girth (3.4%, 4.8%). When a presumably stronger stimulus for an adaptation was added to a weaker one, some additive effects occurred (i.e., increases in 1 RM and thigh girth that were greater in E+S than E; increases in CS activity and repetitions with 80% 1 RM that were greater in S+E than S). When a weaker, although effective, stimulus was added to a stronger one, addition generally did not occur. Concurrent S and E training did not interfere with S or E development in comparison to S or E training alone.     

Comparison between nonlinear and linear periodized resistance training: hypertrophic and strength effects

The aim of this study was to investigate the effects of nonlinear periodized (NLP) and linear periodized (LP) resistance training (RT) on muscle thickness (MT) and strength, measured by an ultrasound technique and 1 repetition maximum (1RM), respectively. Thirty untrained men were randomly assigned to 3 groups: NLP (n = 11, age: 30.2 ± 1.1 years, height: 173.6 ± 7.2 cm, weight: 79.5 ± 13.1 kg), LP (n = 10, age: 29.8 ± 1.9 years, height: 172.0 ± 6.8 cm, weight: 79.9 ± 10.6 kg), and control group (CG; n = 9, age: 25.9 ± 3.6 years, height: 171.2 ± 6.3 cm, weight: 73.9 ± 9.9 kg). The right biceps and triceps MT and 1RM strength for the exercises bench press (BP), lat-pull down, triceps extension, and biceps curl (BC) were assessed before and after 12 weeks of training. The NLP program varied training biweekly during weeks 1-6 and on a daily basis during weeks 7-12. The LP program followed a pattern of intensity and volume changes every 4 weeks. The CG did not engage in any RT. Posttraining, both trained groups presented significant 1RM strength gains in all exercises (with the exception of the BP in LP). The 1RM of the NLP group was significantly higher than LP for BP and BC posttraining. There were no significant differences in biceps and triceps MT between baseline and posttraining for any group; however, posttraining, there were significant differences in biceps and triceps MT between NLP and the CG. The effect sizes were higher in NLP for the majority of observed variables. In conclusion, both LP and NLP are effective, but NLP may lead to greater gains in 1RM and MT over a 12-week training period.     

The effects of accentuated eccentric loading on strength, muscle hypertrophy, and neural adaptations in trained individuals

The purpose of this study was to compare the strength and neuromuscular adaptations for dynamic constant external resistance (DCER) training and dynamic accentuated external resistance (DAER) training (resistance training employing an accentuated load during eccentric actions). Male subjects active in resistance training were assigned to either a DCER training group (n = 10) or a DAER training group (n = 8) for 9 weeks. Subjects in the DCER group performed 4 sets of 10 repetitions with a load of 75% concentric 1 repetition maximum (RM). Subjects in the DAER group performed 3 sets of 10 repetitions with a concentric load of 75% of 1RM and an eccentric load of approximately 120% of concentric 1RM. Three measures reflecting adaptation of elbow flexors and extensors were recorded pretraining and posttraining: concentric 1RM, muscle cross-sectional area (CSA), and specific tension. Strength was assessed at midtraining periods. No significant changes in muscle CSA were observed in either group. Both training groups experienced significant increases in concentric 1RM and specific tension of both the elbow flexors and extensors, but compared with DCER training, DAER training produced significantly greater increases in concentric 1RM of the elbow extensors. These results suggest that, for some exercises, DAER training may be more effective than DCER training in developing strength within a 9-week training phase. However, for trained subjects, neither protocol is effective in eliciting muscle hypertrophy.     

Role of concentric force in limiting improvement in muscular strength

We hypothesized that resistance training with combined eccentric and concentric actions, and concentric action only, should yield similar changes in muscular strength. Subjects in a free weight group trained three times a week for 12 wk with eccentric and concentric actions (FW, n = 16), a second group trained with concentric-only contractions using hydraulic resistance (HY; n = 12), and a control group did not train (n = 11). Training for FW and HY included five sets of supine bench press and upright squat at an intensity of 1-6 repetition maximum (RM) plus five supplementary exercises at 5-10 RM for a total of 20 sets per session for approximately 50 min. Testing at pre-, mid-, and posttraining included 1) 1 RM bench press and squat with and 2) without prestretch using free weights; 3)isokinetic peak force and power for bench press and squat at 5 degrees/s, and isotonic peak velocity and power for bench press with 20-kg load and squat with 70-kg load; 4) hydraulic peak bench press force and power, and peak knee extension torque and power at fast and slow speeds; and 5) surface anthropometry (fatfolds and girths to estimate upper arm and thigh volume and muscle area). Changes in overall fatness, muscularity, and muscle + bone cross-sectional area of the limbs did not differ between groups (P greater than 0.05). Improvements in free weight bench press and squat were similar (P greater than 0.05) in FW (approximately 24%) and HY (approximately 22%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of responses to strenuous eccentric exercise of the elbow flexors between resistance-trained and untrained men

This study compared resistance-trained and untrained men for changes in commonly used indirect markers of muscle damage after maximal voluntary eccentric exercise of the elbow flexors. Fifteen trained men (28.2 +/- 1.9 years, 175.0 +/- 1.6 cm, and 77.6 +/- 1.9 kg) who had resistance trained for at least 3 sessions per week incorporating exercises involving the elbow flexor musculature for an average of 7.7 +/- 1.4 years, and 15 untrained men (30.0 +/- 1.5 years, 169.8 +/- 7.4 cm, and 79.9 +/- 4.4 kg) who had not performed any resistance training for at least 1 year, were recruited for this study. All subjects performed 10 sets of 6 maximal voluntary eccentric actions of the elbow flexors of one arm against the lever arm of an isokinetic dynamometer moving at a constant velocity of 90 degrees .s. Changes in maximal voluntary isometric and isokinetic torque, range of motion, upper arm circumference, plasma creatine kinase activity, and muscle soreness before, immediately after, and for 5 days after exercise were compared between groups. The trained group showed significantly (P < 0.05) smaller changes in all of the measures except for muscle soreness and faster recovery of muscle function compared with the untrained group. For example, muscle strength of the trained group recovered to the baseline by 3 days after exercise, where the untrained group showed approximately 40% lower strength than baseline. These results suggest that resistance-trained men are less susceptible to muscle damage induced by maximal eccentric exercise than untrained subjects.