Thigh-muscles strength training, dance exercise, dynamometry, and anthropometry in professional ballerinas

The purpose of the present study was to assess the effects of 12 weeks of quadriceps and hamstring strength training on torque levels after a dance exercise and on selected anthropometric parameters. The sample consisted of 22 (ages, 25 +/- 1.3 years) full-time professional ballerinas who were randomly assigned into experimental (n = 12) and control (n = 10) groups. A dance routine designed to cause fatigue within 5 minutes, isokinetic dynamometry, and anthropometric assessments were conducted before and after strength training in both groups. Before strength training, the dance routine resulted in significant reductions of hamstring (p < 0.001) and quadriceps (p < 0.001) peak torques in both subject groups. However, after strength training, only control subjects demonstrated such torque decrements (p < 0.001) after the dance routine. Furthermore, the experimental group revealed greater knee extension (119 vs. 138 N.m; p < 0.001) and flexion (60 vs. 69 N.m; p < 0.001) torques, smaller sum of skinfolds (33.6 vs. 27.8 mm; p < 0.01), more fat-free mass (37.7 vs. 39.4 kg; p < 0.05), but unchanged body mass (p > 0.05) and thigh circumferences (p > 0.05). A negative relationship (p < 0.001) was found between initial strength levels and improvements measured at the end of the 12-week program. These results suggest that supplementary strength training for hamstring and quadriceps muscles is beneficial to professional ballerinas and their dancing; weaker individuals are more likely to benefit from such regimens than their stronger counterparts, whereas increases in thigh-muscle strength do not alter selected aesthetic components.     

Are changes in maximal squat strength during preseason training reflected in changes in sprint performance in rugby league players?

Because previous research has shown a relationship between maximal squat strength and sprint performance, this study aimed to determine if changes in maximal squat strength were reflected in sprint performance. Nineteen professional rugby league players (height = 1.84 ± 0.06 m, body mass [BM] = 96.2 ± 11.11 kg, 1 repetition maximum [1RM] = 170.6 ± 21.4 kg, 1RM/BM = 1.78 ± 0.27) conducted 1RM squat and sprint tests (5, 10, and 20 m) before and immediately after 8 weeks of preseason strength (4-week Mesocycle) and power (4-week Mesocycle) training. Both absolute and relative squat strength values showed significant increases after the training period (pre: 170.6 ± 21.4 kg, post: 200.8 ± 19.0 kg, p < 0.001; 1RM/BM pre: 1.78 ± 0.27 kg·kg(-1), post: 2.05 ± 0.21 kg·kg(-1), p < 0.001; respectively), which was reflected in the significantly faster sprint performances over 5 m (pre: 1.05 ± 0.06 seconds, post: 0.97 ± 0.05 seconds, p < 0.001), 10 m (pre: 1.78 ± 0.07 seconds, post: 1.65 ± 0.08 seconds, p < 0.001), and 20 m (pre: 3.03 ± 0.09 seconds, post: 2.85 ± 0.11 seconds, p < 0.001) posttraining. Whether the improvements in sprint performance came as a direct consequence of increased strength or whether both are a function of the strength and power mesocycles incorporated into the players' preseason training is unclear. It is likely that the increased force production, noted via the increased squat performance, contributed to the improved sprint performances. To increase short sprint performance, athletes should, therefore, consider increasing maximal strength via the back squat.     

Occlusion training increases muscular strength in division IA football players

The purpose of this study was to investigate the effectiveness of 4 weeks of low-intensity resistance training with blood-flow occlusion on upper and lower body muscular hypertrophy and muscular strength in National Collegiate Athletic Association Division IA football players. There were 32 subjects (average age 19.2 ± 1.8 years) who were randomized to an occlusion group or control group. The athletes performed 4 sets of bench press and squat in the following manner with or without occlusion: 30 repetitions of 20% predetermined 1 repetition maximum (1RM), followed by 3 sets of 20 repetitions at 20% 1RM. Each set was separated by 45 seconds. The training duration was 3 times per week, after the completion of regular off-season strength training. Data collected included health history, resting blood pressure, pretraining and posttraining bench press and squat 1RM, upper and lower chest girths, upper and lower arm girths, thigh girth, height, and body mass. The increases in bench press and squat 1RM (7.0 and 8.0%, respectively), upper and lower chest girths (3 and 3%, respectively), and left upper arm girth were significantly greater in the experiment group (p < 0.05). Occlusion training could provide additional benefits to traditional strength training to improve muscular hypertrophy and muscular strength in collegiate athletes.     

Short-term effects of resistance training frequency on body composition and strength in middle-aged women

Although a dose-response relationship between resistance training frequency and strength has been identified, there is limited research regarding the association between frequency and body composition. This study evaluated the effects of 3 vs. 4 d·wk(-1) of resistance training on body composition and strength in middle-aged women. Twenty-one untrained women (age 47.6 ± 1.2 years) completed 8 weeks of resistance training either 3 nonconsecutive days of the week using a traditional total-body protocol (RT3) or 4 consecutive days of the week using an alternating split-training protocol (RT4). The RT3 completed 3 sets of 8 exercises, whereas RT4 completed 3 sets of 6 upper body exercises or 6 sets of 3 lower body exercises. Both groups completed 72 sets per week of 8-12 repetitions at 50-80% 1 repetition maximum. Weekly training volume load was calculated as the total number of repetitions × load (kg) completed per week. Body composition was measured using air displacement plethysmography. At baseline and after 8 weeks of resistance training, there were no significant between-group differences. Both protocols resulted in significant increases in absolute lean mass (1.1 ± 0.3 kg; p = 0.001), body weight (1.02 ± 0.3 kg; p = 0.005), body mass index (0.3 ± 0.1 kg·m(-2); p = 0.006), strength (p < 0.001), and weekly training volume load (p < 0.001). Correlation analysis revealed that weekly training volume load was strongly and positively related to gains in lean mass (r = 0.56, p = 0.05) and strength (r = 0.60, p = 0.006). In these untrained, middle-aged women, initial short-term gains in lean mass and strength were not influenced by training frequency when the number of training sets per week was equated.     

Interrelationships between strength, anthropometrics, and strongman performance in novice strongman athletes

The sport of strongman is relatively new; hence, specific research investigating this sport is currently very limited. The purpose of this study was to determine the relationships between anthropometric dimensions and maximal isoinertial strength to strongman performance in novice strongman athletes. Twenty-three semiprofessional rugby union players with considerable resistance training and some strongman training experience (age 22.0 ± 2.4 years, weight 102.6 ± 10.8 kg, height 184.6 ± 6.5 cm) were assessed for anthropometry (height, body composition, and girth measurements), maximal isoinertial performance (bench press, squat, deadlift, and power clean), and strongman performance (tire flip, log clean, and press, truck pull, and farmer's walk). The magnitudes of the relationships were determined using Pearson correlation coefficients, and interpreted qualitatively according to Hopkins (90% confidence limits ～±0.37). The highest relationship observed was between system force (body mass + squat 1-repetition maximum) and overall strongman performance (r = 0.87). Clear moderate to very large relationships existed between performance in all strongman events and the squat (r = 0.61-0.85), indicating the importance of maximal squat strength for strongman competitors. Flexed arm girth and calf girth were the strongest anthropometric correlates of overall strongman performance (r = 0.79 and 0.70, respectively). The results of this study suggest that body structure and common gymnasium-based exercise strength are meaningfully related to strongman performance in novice strongman athletes. Future research should investigate these relationships using more experienced strongman athletes and determine the relationships between changes in anthropometry, isoinertial strength, and strongman performance to determine the role of anthropometry and isoinertial strength in the sport of strongman.     

The effect of strength training on three-kilometer performance in recreational women endurance runners

In this study, we investigated whether a heavy strength training program, as an additive to an endurance running program, would cause significant improvements in 3-km run time in a group of recreationally fit women when compared with endurance-only (EO) training. Sixteen women aged between 18 and 27 years of age were randomly assigned to either an EO group (n = 9) or a concurrent strength and endurance (CSE) group (n = 7). A 10-week training program for both groups consisted of an endurance running program performed three afternoons per week. The CSE group also participated in strength training on the morning of each running session. Testing was conducted pre and post training in a 3-km time trial and measured VO2peak, running economy, muscular strength (1 repetition maximum), and body composition and girth. There was a trend (P = 0.07) toward greater improvement in 3-km performance time for the CSE group (106.7 +/- 91.4 seconds) when compared with the EO group (77.3 +/- 93.0 seconds). Further, the CSE group showed an increase in strength levels when compared with the EO group. The CSE group showed significant increases (P 相似文献   

Using squat testing to predict training loads for the deadlift, lunge, step-up, and leg extension exercises

The purpose of this study was to determine whether there is a linear relationship between the squat and a variety of quadriceps resistance training exercises for the purpose of creating prediction equations for the determination of quadriceps exercise loads based on the squat load. Six-repetition maximums (RMs) of the squat, as well as four common resistance training exercises that activate the quadriceps including the deadlift, lunge, step-up, and leg extension, were determined for each subject. Subjects included 21 college students. Data were evaluated using linear regression analysis to predict quadriceps exercise loads from 6RM squat data and were cross-validated with the prediction of sum of squares statistic. Analysis of the data revealed that the squat is a significant predictor of loads for the dead lift (R2 = 0.81, standard error of the estimate [SEE] = 12.50 kg), lunge (R2 = 0.62, SEE = 12.57 kg), step-up (R2 = 0.71, SEE = 9.58 kg), and leg extension (R2=0.67, SEE = 10.26 kg) exercises. Based on the analysis of the data, the following 6RM prediction equations were devised for each exercise: (a) deadlift load = squat load (0.83) + 14.92 kg, (b) lunge load = squat load (0.52) + 14.82 kg, (c) step-up load = squat load (0.50) + 3.32 kg, and (d) leg extension load = squat load (0.48) + 9.58 kg. Results from testing core exercises such as the squat can provide useful data for the assignment of loads for other exercises.     

Kettlebell swing training improves maximal and explosive strength

The aim of this study was to establish the effect that kettlebell swing (KB) training had on measures of maximum (half squat-HS-1 repetition maximum [1RM]) and explosive (vertical jump height-VJH) strength. To put these effects into context, they were compared with the effects of jump squat power training (JS-known to improve 1RM and VJH). Twenty-one healthy men (age = 18-27 years, body mass = 72.58 ± 12.87 kg) who could perform a proficient HS were tested for their HS 1RM and VJH pre- and post-training. Subjects were randomly assigned to either a KB or JS training group after HS 1RM testing and trained twice a week. The KB group performed 12-minute bouts of KB exercise (12 rounds of 30-second exercise, 30-second rest with 12 kg if <70 kg or 16 kg if >70 kg). The JS group performed at least 4 sets of 3 JS with the load that maximized peak power-Training volume was altered to accommodate different training loads and ranged from 4 sets of 3 with the heaviest load (60% 1RM) to 8 sets of 6 with the lightest load (0% 1RM). Maximum strength improved by 9.8% (HS 1RM: 165-181% body mass, p < 0.001) after the training intervention, and post hoc analysis revealed that there was no significant difference between the effect of KB and JS training (p = 0.56). Explosive strength improved by 19.8% (VJH: 20.6-24.3 cm) after the training intervention, and post hoc analysis revealed that the type of training did not significantly affect this either (p = 0.38). The results of this study clearly demonstrate that 6 weeks of biweekly KB training provides a stimulus that is sufficient to increase both maximum and explosive strength offering a useful alternative to strength and conditioning professionals seeking variety for their athletes.     

Effect of Olympic and traditional resistance training on vertical jump improvement in high school boys

The purpose of this study was to compare the effects of a ballistic resistance training program of Olympic lifts with those of a traditional resistance training program of power lifts on vertical jump improvement in male high school athletes. Twenty-seven male student athletes were recruited from a high school football program at a small, rural school in the Southeast. The subjects were divided into an Olympic training group (OT, n = 11), a power training group (PT, n = 10), and a control group (n = 6). Analysis of variance was used to determine whether a significant mean difference existed among groups on vertical jump improvement after 8 weeks of group-specific training. Effect size of vertical jump improvement between groups, and correlations between strength and vertical jump performance, were also examined. There was no significant mean difference (p >or= 0.05) among OT, PT, and control groups, but large effect sizes between OT and control (d = 1.06) and PT and control (d = 0.94) demonstrate that both OT and PT are effective in improving vertical jump performance in male high school athletes. Moderate to high correlations were noted between squat score and vertical jump after adjusting for body weight (r = 0.42) and between power clean and vertical jump after adjusting for body weight (r = 0.75). Findings from the current study indicate that Olympic lifts as well as power lifts provide improvement in vertical jump performance and that Olympic lifts may provide a modest advantage over power lifts for vertical jump improvement in high school athletes.     

The effects of a calisthenics and a light strength training program on lower limb muscle strength and body composition in mature women

This study evaluated and compared the effectiveness of an aerobics-calisthenics (A-CAL) and an aerobics/weight training (A-WT) programs on lower limb strength and body fat (%). Thirty-five adult women (age 42.1 +/- 5.2 years) were randomly assigned to A-CAL (n = 14), A-WT (n = 14), or a control group (n = 7). The A-CAL and A-WT trained 3 days per week for 10 weeks. Maximal bilateral isometric and isokinetic knee extension (KEXT) and flexion (KFLEX) torque, squat jump (SJ), and body fat (%) were measured before and immediately after training. The results revealed nonsignificant differences between A-CAL and A-WT (p > 0.05). Both A-CAL and A-WT improved SJ (p < 0.001). A-WT increased isometric torque of KEXT and KFLEX (p < 0.05), isokinetic torque of KFLEX (p < 0.05), and decreased body fat (%) (p < 0.05) when compared with controls. In summary, the application of a 10-week light-weight training program improved selected strength parameters of healthy women, compared with controls, but the effectiveness of the calisthenics exercises as an independent form of strength training is dubious.     

The effect of whole-body vibration training and conventional strength training on performance measures in female athletes

The purpose of this study was to examine the effects of regular whole-body vibration (WBV) training on lower body strength and power. National Collegiate Athletic Association Division III softball athletes (n = 9) completed the 9-week protocol as part of their off-season strength and conditioning program. The athletes were randomly assigned to 1 of 2 groups. Week 1, pretesting included 3 repetition maximum (3RM) back squat, standing long jump (SLJ), and vertical countermovement jump (VCMJ). Phase I training (weeks 2-4) consisted of either WBV training (group 1) or conventional strength training (CST, group 2). The primary programmatic difference between WBV and CST was the inclusion of WBV sets after squat sets. Posttesting (3RM squat, SLJ, VCMJ) occurred at week 5. Phase II training (weeks 6-8) consisted of either WBV training (group 2) or CST (group 1). Posttesting was repeated at week 9 after the completion of phase II. Three 2 × 2 mixed factorial analyses of variance were computed. No significant differences (p > 0.05) were found between groups or between groups and testing period for the SLJ, VCMJ, and estimated 1RM back squat. Increases (p < 0.05) were observed in SLJ, VCMJ, and back squat from pretest to posttest 1. Back squat increased (p < 0.05) from posttest 1 to posttest 2. All the athletes experienced significantly greater (p < 0.05) percent changes from pretest to posttest 1 for SLJ and VCMJ. These results indicate that the inclusion of WBV as part of an off-season strength and conditioning program has no apparent benefit over CST methods for collegiate softball players.     

Effects of Swiss-ball core strength training on strength, endurance, flexibility, and balance in sedentary women

The purpose of this study was to investigate the effects of Swiss-ball core strength training on trunk extensor (abdominal)/flexor (lower back) and lower limb extensor (quadriceps)/flexor (hamstring) muscular strength, abdominal, lower back and leg endurance, flexibility and dynamic balance in sedentary women (n = 21; age = 34 ± 8.09; height = 1.63 ± 6.91 cm; weight = 64 ± 8.69 kg) trained for 45 minutes, 3 d·wk-1 for 12 weeks. Results of multivariate analysis revealed significant difference (p ≤ 0.05) between pre and postmeasures of 60 and 90° s trunk flexion/extension, 60 and 240° s-1 lower limb flexion/extension (Biodex Isokinetic Dynamometer), abdominal endurance (curl-up test), lower back muscular endurance (modified Sorensen test), lower limb endurance (repetitive squat test), lower back flexibility (sit and reach test), and dynamic balance (functional reach test). The results support the fact that Swiss-ball core strength training exercises can be used to provide improvement in the aforementioned measures in sedentary women. In conclusion, this study provides practical implications for sedentary individuals, physiotherapists, strength and conditioning specialists who can benefit from core strength training with Swiss balls.     

Influence of compressive gear on powerlifting performance: role of blood flow restriction training

This study investigated the effects of powerlifting gear on training volume and performance, defined by the squat, bench press, and deadlift. Eighteen powerlifters (18-26 years) were randomized into either a group that trained and competed using compressive gear (CG) or without the gear (NON). Training volume, volume progression, and powerlifting performance were assessed before and after 10 weeks of training. Training volume increased in the first 4 weeks for both groups. Volume lifted for squat and the totals were greater in the CG. There was an increase in squat (19.05 ± 30.97 lb, p = 0.02), deadlift (19.05 ± 21.17 lb, p = 0.001), and the total score (44.00 ± 60.44 lb, p = 0.005) for both the groups. The improvements in squat (CG = 33.85 vs. NON = 5.74, p = 0.07) and totals (CG = 66.59 vs. NON = 23.67, p = 0.15) were greater in the CG. Both groups showed a significant and similar increase in the Wilks scores (+13.54 points, p = 0.03). There was a trend toward greater volume progression in those wearing CG during the initial stages of training. Both the groups significantly improved performance for the squat, and deadlift, and had higher totals, and Wilks scores, indicating significant strength gains. The greater magnitude of improvements in the squat and totals for the CG lifters suggests an ergogenic potential of training with powerlifting gear.     

Twitch potentiation after fatiguing exercise in man

Twitch potentiation was studied in the human triceps surae complex before and after intermittent maximal voluntary contractions or electrical stimulation at 20 Hz. Both forms of exercise were conducted with intact circulation for a maximum of 10 min or with circulatory occlusion until force output declined 50%. The relative potentiation was determined when a control twitch was compared to a twitch obtained after 5 s of maximal voluntary plantar flexion. The unpotentiated twitch torque (PT) and potentiated twitch torque (PT*) were reduced most severely after voluntary ischemic exercise (63.2% and 52.5% respectively, (P less than 0.001)). However, the relative potentiation (PT*/PT) immediately after voluntary ischemic exercise increased to 1.65 +/- 0.18 from 1.22 +/- 0.13 at rest. Both PT and PT* recovered quickly after exercise. At rest, twitch contraction time (CT) and one-half relaxation time (1/2 RT) in the unpotentiated twitch were longer than that of contraction (CT*) and one-half relaxation time (1/2 RT*) in the potentiated twitch. Following non-occluded exercise, CT, CT*, 1/2 RT and 1/2 RT* were shortened relative to rest. After ischemic exercise CT and CT* were shortened although 1/2 RT and 1/2 RT* increased relative to rest. Both CT* and 1/2 RT* quickly recovered to pre-exercise values by 5 min post-exercise. Ratios of potentiated/control twitch parameters were not altered after nonoccluded exercise, but were increased after ischemic exercise. These results suggest that the mechanisms of fatigue which depress voluntary torque and twitch and potentiated twitch torques, do not interfere with the extent of potentiation after fatiguing exercise.     

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.     

Specificity of joint angle in isometric training

Six healthy women (21.8 +/- 0.4 y) did isometric strength training of the left plantarflexors at an ankle joint angle of 90 degrees. Training sessions, done 3 times per week for 6 weeks, consisted of 2 sets of ten 5 s maximal voluntary contractions. Prior to and following the training, and in random order, voluntary and evoked isometric contraction strength was measured at the training angle and at additional angles: 5 degrees, 10 degrees, 15 degrees, and 20 degrees intervals in the plantarflexion and dorsiflexion directions. Evoked contraction strength was measured as the peak torque of maximal twitch contractions of triceps surae. Training increased voluntary strength at the training angle and the two adjacent angles only (p less than 0.05). Time to peak twitch torque was not affected by training. Twitch half relaxation time increased after training (p = 0.013), but the increase was not specific to the training angle. There was a small (1.1%, p less than 0.05) increase in calf circumference after training. Evoked twitch torque did not increase significantly at any joint angle. It was therefore concluded that a neural mechanism is responsible for the specificity of joint angle observed in isometric training.     

The effects of plyometric, tennis-drills, and combined training on reaction, lateral and linear speed, power, and strength in novice tennis players

Reaction time, first-step quickness, lateral (side steps), and forward speed over short distances are important parameters for tennis performance. The aims of this study were: (i) to diagnose the presence of laterality in tennis lateral movements and (ii) to compare the effects of plyometric training (PT), tennis-specific drills training (TDT), and combined training (CT) on performance in tennis-specific movements and power/strength of lower limbs. Sixty-four novice tennis players (21.1 +/- 1.3 years) were equally (n = 16) assigned to a control (C), PT, TDT, or CT. Training was performed 3 times/week for 9 weeks. Testing was conducted before and after training for the evaluation of reaction time (single lateral step), 4-m lateral and forward sprints, 12-m forward sprints with and without turn, reactive ability, power, and strength. There was a significant difference in lateral speed (side-steps) between the 2 sides (P < 0.05). PT, TDT, or CT improved the 4m lateral and forward sprints (P < 0.05). PT and CT improved also the reaction time of the "slow" side (P < 0.05), whereas TDT and CT improved the 12-m sprint performances with and without turn (P < 0.05). Power and strength improved in most tests after PT and CT. Lateral and forward sprints were correlated (r = -0.50 to -0.75; P < 0.05) with power/strength. In conclusion, PT improved fitness characteristics that rely more on reactive strength and powerful push-off of legs such as, lateral reaction time, 4-m lateral and forward sprints, drop jump and maximal force. TDT improved all 4-m and 12-m sprint performances, whereas CT appeared to incorporate the advantage of both programs and improved most tests items. Tennis coaches should be aware that each training regimen may induce more favorable changes to different aspects of fitness.     

Effects of creatine supplementation and three days of resistance training on muscle strength, power output, and neuromuscular function

Previous studies have demonstrated increases in peak torque (PT) and decreases in acceleration time (ACC) after only 2 days of resistance training, and other studies have reported improvements in isokinetic performance after 5 days of creatine supplementation. Consequently, there may be a combined benefit of creatine supplementation and short-term resistance training for eliciting rapid increases in muscle strength, which may be important for short-term rehabilitation and return-to-play for previously injured athletes. The purpose of this study, therefore, was to examine the effects of 3 days of isokinetic resistance training combined with 8 days of creatine monohydrate supplementation on PT, mean power output (MP), ACC, surface electromyography (EMG), and mechanomyography (MMG) of the vastus lateralis muscle during maximal concentric isokinetic leg extension muscle actions. Twenty-five men (mean age +/- SD = 21 +/- 3 years, stature = 177 +/- 6 cm, and body mass = 80 +/- 12 kg) volunteered to participate in this 9-day, double-blind, placebo-controlled study and were randomly assigned to either the creatine (CRE; n = 13) or placebo (PLA; n = 12) group. The CRE group ingested the treatment drink (280 kcal; 68 g carbohydrate; 10.5 g creatine), whereas the PLA group received an isocaloric placebo (70 g carbohydrate). Two servings per day (morning and afternoon) were administered in the laboratory on days 1-6, with only 1 serving on days 7-8. Before (pre; day 1) and after (post; day 9) the resistance training, maximal voluntary concentric isokinetic leg extensions at 30, 150, and 270 degrees x s(-1) were performed on a calibrated Biodex System 3 dynamometer. Three sets of 10 repetitions at 150 degrees x s(-1) were performed on days 3, 5, and 7. Peak torque increased (p = 0.005; eta(2) = 0.296), whereas ACC decreased (p < 0.001; eta(2) = 0.620), from pretraining to posttraining for both the CRE and PLA groups at each velocity (30, 150, and 270 degrees x s(-1)). Peak torque increased by 13% and 6%, whereas ACC decreased by 42% and 34% for the CRE and PLA groups, respectively, but these differences were not statistically significant (p > 0.05). There were no changes in MP, EMG, or MMG amplitude; however, EMG median frequency (MDF) increased, and MMG MDF increased at 30 degrees x s(-1), from pretraining to posttraining for both the CRE and PLA groups. These results indicated that 3 days of isokinetic resistance training was sufficient to elicit small, but significant, improvements in peak strength (PT) and ACC for both the CRE and PLA groups. Although the greater relative improvements in PT and ACC for the CRE group were not statistically significant, these findings may be useful for rehabilitation or strength and conditioning professionals who may need to rapidly increase the strength of a patient or athlete within 9 days.     

Effects of resistance training intensity on sleep quality and strength recovery in trained men: a randomized cross-over study

Resistance training (RT) variables can affect sleep quality, strength recovery and performance. The aim of this study was to examine the acute effect of RT leading to failure vs. non-failure on sleep quality (SQ), heart rate variability (HRV) overnight and one-repetition maximum (1-RM) performance 24 hours after training. Fifteen resistance-trained male athletes (age: 23.4 ± 2.4 years; height 178.0 ± 7.6 cm; weight: 78.2 ± 10.6 kg) performed two training sessions in a randomized order, leading to failure (4x10) or non-failure (5x8(10) repetitions), with 90 seconds for resting between sets at 75% 1-RM in bench press (BP) and half squat (HS). The day after, the participants completed the predicted 1-RM test for both exercises. In addition, the subjective and actigraphic SQ and HRV during sleep were measured after each training session. The day after the training protocol leading to failure, the 1-RM of BP (MD = 7.24 kg; -7.2%; p < 0.001) and HS (MD = 20.20 kg; -11.1%; p < 0.001) decreased. However, this parameter did not decrease after a non-failure RT session. No differences were observed between failure and non-failure training sessions on SQ and HRV; therefore, both types of training sessions similarly affected the SQ and the autonomic modulation during the night after the training session. This study provides an insight into the influence of different training strategies on SQ, strength performance and recovery after moderate- to high-demand training. This information could be useful especially for professional coaches, weightlifters and bodybuilders, due to the potential influence on the programming processes.     

Changes in strength over a 2-year period in professional rugby union players

The purpose of this study was to assess the magnitude of upper and lower body strength changes in highly trained professional rugby union players after 2 years of training. An additional purpose was to examine if the changes in strength were influenced by the starting strength level, lean mass index (LMI), or chronological age. This longitudinal investigation tracked maximal strength and body composition over 3 consecutive years in 20 professional rugby union athletes. Maximal strength in the bench press and back squat and body composition was assessed during preseason resistance training sessions each year. The athletes completed a very rigorous training program throughout the duration of this study consisting of numerous resistance, conditioning and skills training sessions every week. The primary findings of this study were as follows: (a) Maximal upper and lower body strength was increased by 6.5-11.5% after 2 years of training (p = 0.000-0.002 for bench press; p = 0.277-0.165 for squat); (b) magnitude of the improvement was negatively associated with initial strength level (r = -0.569 to -0.712, p ≤ 0.05); (c) magnitude of improvement in lower body maximal strength was positively related to the change in LMI (an indicator of hypertrophy; r = 0.692-0.880, p ≤ 0.05); and (d) magnitude of improvement was not associated with the age of professional rugby union athletes (r = -0.068 to -0.345). It appears particularly important for training programs to be designed for continued muscle hypertrophy in highly trained athletes. Even in professional rugby union athletes, this must be achieved in the face of high volumes of aerobic and skills training if strength is to be increased.