Maximal Dynamic Strength Research Articles

Effects of eccentric-focused and conventional resistance training on strength and functional capacity of older adults.

The aim of the study was to assess the effect of eccentric training using a constant load with longer exposure time at the eccentric phase on knee extensor muscle strength and functional capacity of elderly subjects in comparison with a conventional resistance training program. Twenty-six healthy elderly women (age = 67 ± 6 years) were randomly assigned to an eccentric-focused training group (ETG; n = 13) or a conventional training group (CTG; n = 13). Subjects underwent 12 weeks of resistance training twice a week. For the ETG, concentric and eccentric phases were performed using 1.5 and 4.5 s, respectively, while for CTG, each phase lasted 1.5 s. Maximum dynamic strength was assessed by the one-repetition maximum (1RM) test in the leg press and knee extension exercises, and for functional capacity, subjects performed specific tests (6-m walk test, timed up-and-go test, stair-climbing test, and chair-rising test). Both groups improved knee extension 1RM (24-26 %; p = 0.021), timed up-and-go test (11-16 %; p < 0.001), 6-m walk test (9-12 %; p = 0.004), stair-climbing test (8-13 %; p = 0.007), and chair-rising test (15-16 %; p < 0.001), but there was no significant difference between groups. In conclusion, the strategy of increasing the exposure time at the eccentric phase of movement using the same training volume and intensity does not promote different adaptations in strength or functional capacity compared to conventional resistance training in elderly woman.

Effects of Single Vs. Multiple Sets Water-Based Resistance Training on Maximal Dynamic Strength in Young Men.

The aim of this study was to compare the effects of single vs. multiple sets water-based resistance training on maximal dynamic strength in young men. Twenty-one physically active young men were randomly allocated into 2 groups: a single set group (SS, n=10) and a multiple sets group (MS, n=11). The single set program consisted of only 1 set of 30 s, whereas the multiple sets comprised 3 sets of 30 s (rest interval between sets equaled 1 min 30 s). All the water-based resistance exercises were performed at maximal effort and both groups trained twice a week for 10 weeks. Upper (bilateral elbow flexors and bilateral elbow extensors, peck deck and inverse peck deck) as well as lower-body (bilateral knee flexors and unilateral knee extensors) one-repetition maximal tests (1RM) were used to assess changes in muscle strength. The training-related effects were assessed using repeated measures two-way ANOVA (α=5%). Both SS and MS groups increased the upper and lower-body 1RM, with no differences between groups. Therefore, these data show that the maximal dynamic strength significantly increases in young men after 10 weeks of training in an aquatic environment, although the improvement in the strength levels is independent of the number of sets performed.

Effect of Different Interrepetition Rest Periods on Barbell Velocity Loss During the Ballistic Bench Press Exercise.

This study investigated the effect of introducing different interrepetition rest (IRR) periods on the ability to sustain maximum bench press throw velocity with a range of loads commonly used to develop upper-body power. Thirty-four physically active collegiate men (age: 21.5 ± 2.8 years; body mass: 75.2 ± 7.2 kg; height: 176.9 ± 4.9 cm) were tested during 2 consecutive weeks. During the first week, the maximum dynamic strength (repetition maximum [RM]) in bench press exercise was determined (RM = 76.7 ± 13.2 kg). The following week, 3 testing sessions were conducted with 48 hours apart in random order. In each day of evaluation, only 1 load (30%RM, 40%RM, or 50%RM) was assessed in the bench press throw exercise. With each load, subjects performed 3 single sets of 15 repetitions (15-minute interset rest) with 3 different sets configurations: continuous repetitions (CR), 6 seconds of IRR (IRR6), and 12 seconds of IRR (IRR12). The decrease of peak velocity (PV) was significantly lower for IRR12 compared with CR and IRR6 at least since the repetition 4. No differences between CR and IRR6 protocols were found until the repetition 7 at 30%RM and 40%RM and until the repetition 5 at 50%RM. The decrease of PV during the CR protocol was virtually linear for the 3 loads analyzed (r > 0.99); however, this linear relationship became weaker for IRR6 (r = 0.79-0.95) and IRR12 (r = 0.35-0.87). These results demonstrate that IRR periods allow increasing the number of repetitions before the onset of significant velocity losses.

Effects of exercise intensity and occlusion pressure after 12 weeks of resistance training with blood-flow restriction.

We compared the effects of different protocols of blood-flow restriction training (BFRT) with different occlusion pressures and/or exercise intensities on muscle mass and strength. We also compared BFRT protocols with conventional high-intensity resistance training (RT). Twenty-six subjects had each leg allocated to two of five protocols. BFRT protocols were performed at either 20 or 40 % 1-RM with either 40 or 80 % occlusion pressure: BFRT20/40, BFRT20/80, BFRT40/40, and BFRT40/80. Conventional RT was performed at 80 % 1-RM (RT80) without blood-flow restriction. Maximum dynamic strength (1-RM) and quadriceps cross-sectional area (CSA) were assessed at baseline and after 12 weeks. Regarding muscle mass, increasing occlusion pressure was effective only at very low intensity (BFRT20/40 0.78 % vs. BFRT20/80 3.22 %). No additional increase was observed at higher intensities (BFRT40/40 4.45 % vs. BFRT40/80 5.30 %), with no difference between the latter protocols and RT80 (5.90 %). Exercise intensity played a role in CSA when comparing groups with similar occlusion pressure. Muscle strength was similarly increased among BFRT groups (~12.10 %) but to a lesser extent than RT80 (21.60 %). In conclusion, BFRT protocols benefit from higher occlusion pressure (80 %) when exercising at very low intensities. Conversely, occlusion pressure seems secondary to exercise intensity in more intense (40 % 1-RM) BFRT protocols. Finally, when considering muscle strength, BFRT protocols seem less effective than high-intensity RT.

Effects of Strength Training Associated With Whole-Body Vibration Training on Running Economy and Vertical Stiffness.

Running economy (RE) is defined as the energy cost to maintain a submaximal running velocity and seems to be affected by individual's neuromuscular characteristics, such as stiffness level. Both resistance training (RT) and whole-body vibration training added to RT (WBV + RT) have been shown to influence those characteristics. Thus, it is conceivable that RT and WBV + RT could also affect RE. The objective of this study was to investigate if a 6-week training period of RT and WBV + RT influences RE and vertical stiffness (VS). Fifteen recreational runners were divided into RT or WBV + RT groups. Running economy, VS, and lower-limb maximum dynamic strength (1 repetition maximum [1RM] half-squat) were assessed before and after the 6-week training period. There was a main time effect for 1RM, but no other statistically significant difference was observed. Neither conventional RT nor RT performed on a WBV platform improved VS and RE in recreational long distance runners. It is possible that movement velocity was rather low, and utilization of stretch-shortening cycle might have been compromised, impairing any expected improvement in RE.

Predicting Maximal Dynamic Strength From the Load-Velocity Relationship in Squat Exercise.

The aim of this study was to develop a rapid indirect method to determine an individual's maximal strength or 1 repetition maximum (RM) in untrained subjects during half-squat exercise. One hundred and five physically active young subjects (87 men and 18 women) performed a submaximal and a maximal load test during half-squat exercises on a Smith machine. In the submaximal test, subjects completed 3 repetitions with a load equivalent to body weight. The velocity and power of barbell displacement were recorded during the upward movement from 90° of knee flexion. All repetitions were performed at maximum velocity. In a subsequent 1-2RM test, the 1RM for the exercise was calculated. The variables' load and mean velocity (V(mean)) were used to construct an adjusted 1RM prediction model, which was capable of estimating the 1RM with an accuracy of 58% (F(exp) = 72.82; 2; 102 df; p ≤ 0.001). Our results indicate a good correlation between the mean displacement velocity of a load equivalent to body weight and 1RM. This relationship enables a safe and fast estimation of 1RM values in half-squat exercise (1RM = -61.93 + [121.92·V(mean)] + [1.74·load]) and provides valuable information to untrained subjects who are starting resistance training programs.

Effects of Water-based Concurrent Resistance and Aerobic Training in Inactive Young Women

PURPOSE: The aim was to investigate the effects of the intra-session exercise order in water-based concurrent training on peak oxygen uptake, isometric and concentric peak torques and maximal dynamic strength in young women. METHODS: Twenty-six women (25.1 ± 2.9 years) were placed into two groups: resistance before (RA) or after (AR) aerobic training. Subjects trained resistance (sets at maximal effort) and aerobic training (at heart rate in the anaerobic threshold) during 12 weeks (twice a week) performing both exercise types in the same training session. Bruce protocol was used to determine the peak oxygen uptake of the subjects. The isometric and concentric peak torques during knee flexion and elbow extension were measured with a Biodex dynamometer at 60°.s-1. Maximal dynamic strength was assessed using the 1 repetition maximal test (1RM) on the bilateral knee flexion and elbow extension. The training-related effects were assessed using a two-way ANOVA with repeated measures. RESULTS: The peak oxygen uptake showed significant increases after training (RA: 6.79 ± 7.40 vs. AR: 5.07 ± 4.32%, p<0.001) and both groups presented similar gains. After training, there were significant improvements on isometric peak torque during knee flexion (RA: 9.02 ± 4.87 vs. AR: 9.44 ± 8.19%, p<0.001) and on concentric peak torque during knee flexion (RA: 9.24 ± 10.39 vs. AR: 14.46 ± 9.86%, p<0.001) and elbow extension (RA: 6.99 ± 11.16 vs. AR: 2.74 ± 10.69%, p=0.042), with no difference between groups. Significant increases were found after training on bilateral knee flexion (RA: 27.14 ± 13.43 vs. AR: 23.93 ± 19.05%, p<0.001) and elbow extension 1RM (RA: 21.88 ± 11.70 vs. AR: 17.0 ± 17.73%, p<0.001), with no difference between groups. CONCLUSION: The intra-session exercise order in water-based concurrent training had no influence on the peak oxygen uptake, isometric and concentric peak torques and maximal dynamic strength in young women. Supported by CAPES, CNPq and FINEP.

Same-session Versus Different-Day Combined Strength And Endurance Training

Training for strength (S) and endurance (E) in the same session has previously been shown to induce similar changes in body composition and physical performance independent of the exercise order (1). Training S and E on different days requires more frequent individual training sessions to match the training volume, possibly resulting in higher post-exercise energy consumption (2). PURPOSE: To compare changes in body composition and physical fitness during same-session (SS) and different-day (DD) combined S and E training in women. METHODS: Physically active women were assigned to a SS (n=23, 30±5 yrs, 165±6 cm, 64±10 kg) or DD (n=18, 30±8 yrs, 168±5 cm, 66±8 kg) group and trained 2-3 d·w-1 (S and E in one session) or 4-6 d·w-1 (S and E on alternating days) for 24 wks. The exercise order for SS was randomized and maintained throughout 24 wks (S preceding E or vice versa). Lean and fat mass were assessed by DXA for upper (UB), lower (LB) and total body (TB). Maximal dynamic leg press strength (1RM) and endurance performance (maximal Watts, Wmax) during an incremental cycling test were measured. Subjects were required to maintain normal dietary intake throughout the intervention. RESULTS: DD significantly decreased fat mass (UB -16±16% p=0.002, btw-groups p<0.001; LB -10±13% p=0.018, btw-groups p=0.002; TB -13±14% p=0.004, btw-groups p<0.001), while changes in fat mass in SS were not significant (p>0.05). Both SS and DD increased lean mass in UB (SS 3±4% p=0.019 and DD 5±6% p=0.006), LB (SS 3±3% p=0.001 and DD 4±2% p<0.001) and TB (SS 3±2% p<0.001 and DD 5±3% p<0.001, btw-groups p=0.039). Body weight remained unchanged (p>0.05) in both groups. Both training modes increased 1RM (SS 17±11%, p<0.001 and DD 21±8%, p<0.001) and Wmax (SS 13±9%, p<0.001 and DD 22±14%, p<0.001). CONCLUSION: The main finding was that both SS and DD significantly increased lean mass and S and E performances, but reductions in fat mass were only observed following DD training. This may be due to possibly increased post-exercise energy demands in DD due to more frequent individual training sessions. Thus, DD training may be recommended for individuals aiming to optimize body composition.

Different Training Frequencies Maintain Muscle Power Performance After A Reduced Strength Training Period

Reduced strength training (RST) has been suggested to maintain muscle power performance achieved after a regular training period. This decrease is characterized by the manipulation of training volume and frequency aiming to avoid the negative effects of detraining. However, the effects of different training frequencies during RST on muscle power performance remain unknown. PURPOSE: To investigate the effects of different training frequencies during a RST period on muscle power performance. METHODS: Thirty three physically active male subjects were randomly assigned to three experimental groups: reduced strength training 2 (RST2 = two sessions per week), reduced strength training 1 (RST1 = one session per week) and detraining (DT = interrupted training). All three groups performed 8 weeks of high intensity strength training (ST) divides into two 4-wk periods (i.e. 2.d.wk-1 during 4 wk and 3.d.wk-1 at last 4 wks). After the ST, the RST1 and RT2 reduced the session volume (RST 2 = 2 x 8-6RM per session; RST 1 = 4 x 8-6RM per session) and training-frequency over 8 more weeks, while the DT group detrained. Maximal strength (1RM) and muscle power (PPw) in the half squat exercise, and Countermoviment jump height (CMJ) were measured before, after ST, and after RST. RESULTS: RST1, RST2 and DT showed similar increases in the 1RM after the ST 37.3 (±1,61%), 38.3 (±1,69%), and 41.7 (±2,61%) (p<0.01), respectively. The PPw and CMJ also increased similarly after ST 11.30 (±2.86%), 12.06 (±6.40%), and 10.77 (±5.14%) and 3.7 (±1.4%), 4.1 (±1.9), and 4.1 (±1.2), respectively. After the RST period, RST1 and RST2 groups were able to maintain their performance while DT showed significant decreased in 1RM 23.7 (±3.79%), PPw 34.86 (±12.30%), and CMJ 4.4 (±0.97%). CONCLUSION: These results support that different training frequencies during a RST period were able to maintain maximal dynamic strength and muscle power performance in physically active subjects.

Enhancing Performance in Professional Water Polo Players

We compared the effects of 6 weeks of dryland, in-water-specific strength training and plyometric training combined with a water polo (WP) training program on 7 sport-specific performance parameters. Thirty professional players were randomly assigned to 3 experimental groups: combined training (CG), in-water-specific strength (WSG), and plyometrics (PG). The program included 3 weekly strength training sessions and 5 days of WP training per week for a total of 6 weeks during the preseason. The 10-m T-agility test, 20-m maximal sprint swim, maximal dynamic strength (1 repetition maximum [1RM], bench press [BP] and full squat [FS]), in-water boost, countermovement jump (CMJ) and throwing speed (ThS) were measured before and after the 6-week training period. There were no significant differences between the groups for any of the tested variables before the initiation of the 6-week training period. After 6 weeks of training, significant improvements (p ≤ 0.001) were found in the PG group for the CMJ (6.1%) and in all groups for the in-water boost (4.4-5.1%) test. The 1RM BP (7.6-12.6%) and FS (11.5-14.6%) significantly (p ≤ 0.05) increased in all groups. Additionally, ThS significantly increased in all groups (11.4-17.5%), whereas the agility test was significantly decreased (-7.3%) in only the CG group. Combined, in-water-specific strength and plyometric training produced medium to large effects on most WP-specific performance parameters. Therefore, we propose preseason WP training should include a combined training program that contains dryland and in-water-specific strength and plyometric training to optimize the WP preparation for competition.

A single set of exhaustive exercise before resistance training improves muscular performance in young men.

The purpose of this study was to examine the effects of an additional set of exhaustive exercise before traditional hypertrophic training on quadriceps muscle performance in young men. Subjects performed maximal dynamic strength (1RM), local muscular endurance (LME), and magnetic resonance imaging (MRI) tests before and after an 8-week hypertrophic training program using a knee extensor machine. After baseline testing, the subjects were divided into 3 groups: untrained control, traditional training (TR), and prior exhaustive training (PE). Both the TR and PE groups trained using the same training protocol (2 days week(-1); 3 sets of 8-12 repetitions at 75 % of 1RM); the only difference was that the PE group performed an additional set of exhaustive exercise at 20 % of 1RM before each training session. After 8 weeks, the PE group experienced a greater (P < 0.05) increase in 1RM, cross-sectional area, and LME than the TR group. Additionally, no changes (P > 0.05) in daily dietary intake were observed between groups. These results suggest that the inclusion of a single set of exhaustive exercise at 20 % of 1RM before traditional hypertrophic training can be a suitable strategy for inducing additional beneficial effects on quadriceps strength, hypertrophy, and endurance in young men.

Effects of resistance training on neuromuscular characteristics and pacing during 10-km running time trial.

The purpose of this study was to analyze the impact of an 8-week strength training program on the neuromuscular characteristics and pacing adopted by runners during a self-paced endurance running. Eighteen endurance runners were allocated into either strength training group (STG, n = 9) or control group (CG, n = 9) and performed the following tests before and after the training period: (a) incremental test, (b) running speed-constant test, (c) 10-km running time trial, (d) drop jump test, (e) 30-s Wingate anaerobic test, (f) maximum dynamic strength test (1RM). During 1RM, the electromyographic activity was measured. In the STG, the magnitude of improvement for 1RM (23.0 ± 4.2 %, P = 0.001), drop jump (12.7 ± 4.6 %, P = 0.039), and peak treadmill speed (2.9 ± 0.8 %, P = 0.013) was significantly higher compared to CG. This increase in the 1RM for STG was accompanied by a tendency to a higher electromyographic activity (P = 0.080). The magnitude of improvement for 10-km running performance was higher (2.5 %) for STG than for CG (-0.7 %, P = 0.039). Performance was improved mainly due to higher speeds during the last seven laps (last 2800 m) of the 10-km running trial. There were no significant differences between before and after training period for maximal oxygen uptake, respiratory compensation point, running economy, and anaerobic performance for both groups (P > 0.05). These findings suggest that a strength training program offers a potent stimulus to counteract fatigue during the last parts of a 10-km running race, resulting in an improved overall running performance.

Effects of two deep water training programs on cardiorespiratory and muscular strength responses in older adults

This study aimed to investigate the effects of two deep water training programs on cardiorespiratory and muscular strength responses in older adults. Thirty-four older adults men were placed into two groups: deep water endurance training (ET; n=16; 66±4years) and deep water strength prior to endurance training (concurrent training: CT; n=18; 64±4years). The training period lasted 12weeks, with three sessions a week. The resting heart rate and the oxygen uptake at peak (VO2peak) and at the second ventilatory threshold (VO2VT2) were evaluated during a maximal incremental test on a cycle ergometer before and after training. In addition, maximal dynamic strength (one repetition maximum test — 1RM) and local muscular resistance (maximum repetitions at 60% 1RM) of the knee extensors and flexors were evaluated. After the training period, the heart rate at rest decreased significantly, while the VO2peak and VO2VT2 showed significant increases in both groups (p<0.05). Only the VO2VT2 resulted in significantly greater values for the ET compared to the CT group after the training (p<0.05). In addition, after training, there was a significant increase in the maximal dynamic strength of the knee extensors and the local muscular endurance of the knee extensors and flexors, with no difference between the groups (p>0.05). In summary, the two training programs were effective at producing significant improvements in cardiorespiratory and muscular strength responses in older adult men. However, deep water endurance training at high intensities provides increased cardiorespiratory responses compared to CT and results in similar muscular strength responses.

Changes of Body Composition, Muscular Strength and Physical Performance Due to Resistance Training in Older Persons with Sarcopenic Obesity.

At present, it is unclear whether older, obese persons with or without sarcopenia respond differently to training. Furthermore, there are no differentiated recommendations for resistance training for this special target group. The objectives are to investigate the changes in the physical parameters of older, obese men caused by training and to reappraise the modalities of resistance training for older persons. Pre-test-post-test design. The participants were 33 physically inactive and obese older men (≥ 65 years, BMI ≥30 kg/m2), with-out severe diseases. Subjects were divided into two groups: NSAR (no or presarcopenia, n= 15) or SAR (sarcopenia, n= 18). The intervention consisted of progressive resistance training, twice a week for 16 weeks with finally 80-85% of maximum strength and three sets with 8-12 repetitions. The training contained six exercises for the major muscle groups. Sarcopenia was assessed using the Short Physical Performance Battery (SPPB), hand-grip strength, skeletal muscle mass index (SMI), and gait speed over a 6-meter walkway. Furthermore, the maximum dynamic strength (1 RM) was assessed. At baseline, the NSAR group had significantly better values in SMI, SPPB score, hand-grip strength, and 1 RM. After training, the results in both groups displayed an increase in 1 RM at the lower limbs (NSAR 18%, SAR 38%) and the upper limbs (NSAR 12%, SAR 14%). Also, the SPPB score (NSAR 11%, SAR 15%) and the 6-m-gait speed (NSAR 5%, SAR 10%) increased. The SAR group was able to increase their right hand-grip strength by 12%, whereas the NSAR group maintained their initial high strength values. SMI did not change in both groups. Both groups show improvements after resistance training with slightly more benefits for men with sarcopenia. Results of this study can be used to define specific training regimens for N(SAR) subjects.

Physiological Adaptations to Resistance Training in Prepubertal Boys

Purpose: The purpose of this study was to investigate the physiological adaptations of resistance training (RT) in prepubertal boys. Methods: Eighteen healthy boys were divided into RT (n = 9, Mage = 10.4 ± 0.5 years) and control (CTR; n = 9, Mage = 10.9 ± 0.7 years) groups. The RT group underwent a resistance training during 12 weeks, 3 times per week, performing 3 sets of 6 to 15 repetitions at intensities ranging from 60% to 80% of maximal dynamic strength (1-repetition maximum [1-RM] values). Before and after the training, the groups were assessed in their body mass and composition (dual-energy X-ray absorptiometry), isokinetic dynamometry, 1-RM, and ergoespirometry. Moreover, force per unit of muscle volume was calculated by the quotient between 1-RM and lean mass. Results: Both groups presented statistically significant (p < .05) increases in the 1-RM and force per unit of muscle volume in the knee extension and elbow flexion, but these strength increases were statistically significantly greater in the RT group (effect size [ES] = 2.83–9.00) than in the CTR group (ES = 0.72–1.00). Moreover, both groups statistically significantly increased in lean body mass variables (ES = 0.12–0.38). However, increases in the fat mass variables occurred only in the CTR group (ES = − 0.01–0.50), whereas no changes were observed in the RT group. Furthermore, there were statistically significant increases in all bone mineral content variables (ES = 0.13–0.43), without differences between groups. No cardiorespiratory changes were observed. Conclusion: Twelve weeks of RT was effective in improving strength and force per unit of muscle volume and prevented fat mass increases in boys.

Strength training prior to endurance exercise: impact on the neuromuscular system, endurance performance and cardiorespiratory responses.

This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise.

Women with polycystic ovary syndrome have greater muscle strength irrespective of body composition

The aim of this study was to compare metabolic parameters, body composition (BC) and muscle strength of women with and without polycystic ovary syndrome (PCOS). This was a case–control study that evaluated 40 women with PCOS and 40 controls. Androgens and insulin resistance were measured. BC was based on dual-energy X-ray absorptiometry. Isometric handgrip and maximal dynamic muscle strength (1-RM) strength tests were performed. Median total testosterone (p < 0.01), free androgen index (p < 0.01), insulin (p < 0.01) and homeostasis model assessment-insulin resistance (p = 0.02) were higher and sex hormone binding globulin (SBHG) (p = 0.04) was lower in the PCOS group. Normoweight women with PCOS had higher percentages of android body fat. However, the prevalence of android fat distribution was higher in the PCOS than in the control group (p = 0.04). The strength 1-RM in bench press (p < 0.01), muscle strength relative to lean muscle mass in the dominant lower limb (p = 0.04) and isometric handgrip strength tests (p = 0.03) was higher in the PCOS group. PCOS was a determinant of strength in the bench press exercise (p = 0.04). The hyperandrogenism was a predictor of increased strength in biceps curl exercises (p = 0.03) in the dominant lower limb (p = 0.02) and isometric handgrip strength (p = 0.03). In conclusion, women with PCOS have greater muscle strength and a higher prevalence of central obesity, but no difference in BC. Muscle strength may be related to high androgen levels in these women.

Safety and possible effects of low-intensity resistance training associated with partial blood flow restriction in polymyositis and dermatomyositis.

IntroductionOur aim was to evaluate the safety and efficacy of a low-intensity resistance training program combined with partial blow flow restriction (BFR training) in a cohort of patients with polymyositis (PM) and dermatomyositis (DM).MethodsIn total, 13 patients with PM and DM completed a 12-week twice a week low-intensity (that is, 30% one-repetition-maximum (1RM)) resistance exercise training program combined with partial blood flow restriction (BFR). Assessments of muscle strength, physical function, quadriceps cross sectional (CSA) area, health-related quality of life, and clinical and laboratory parameters were assessed at baseline and after the intervention.ResultsThe BFR training program was effective in increasing the maximal dynamic strength in both the leg-press (19.6%, P <0.001) and knee-extension exercises (25.2% P <0.001), as well as in the timed-stands (15.1%, P <0.001) and timed-up-and-go test (−4.5%, P =0.002). Quadriceps CSA was also significantly increased after the intervention (4.57%, P =0.01). Similarly, all of the components of the Short Form-36 Health Survey, the Health Assessment Questionnaire scores, and the patient- and physician reported Visual Analogue Scale were significantly improved after training (P <0.05). Importantly, no clinical evidence or any other self-reported adverse event were found. Laboratory parameters (creatine kinase and aldolase) were also unchanged (P >0.05) after the intervention.ConclusionsWe demonstrated that a 12-week supervised low-intensity resistance training program associated with partial blood flow restriction may be safe and effective in improving muscle strength and function as well as muscle mass and health-related quality of life in patients with PM and DM.Trial registrationClinicaltrials.gov NCT01501019. Registered November 29, 2011.

Effects of high and low volume of strength training on muscle strength, muscle volume and lipid profile in postmenopausal women

Changes in lipid profile are considered a risk factor for cardiovascular disease (CVD), especially in postmenopausal woman who have been associated with age-related loss of muscle mass. The beneficial role of aerobic exercise in the prevention of CVD has been well documented. However, the effect of strength training has not been established. The purpose of this study was to determine the changes of lipoprotein levels after 12 weeks of different volumes of strength training and its correlation with strength and muscle volume in postmenopausal women. The participants were randomized into three groups: low volume (LVST; n = 12, 1 set) and high volume of strength training (HVST; n = 11, 3 sets), or control group (n = 12). Training groups performed 12 weeks of supervised strength exercises, 15 maximum repetitions, five times a week, 20 minutes for LVST and 40 minutes for HVST for each training session. Measurements included body composition, strength and muscle volume, as well as blood analysis (glucose, total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein) pre- and post-training. The HVST and LVST improved the one-repetition maximum knee extension strength (p < 0.001), maximal dynamic strength (p < 0.001), and muscle volume (p = 0.048). Post-training triglyceride was lower in HVST when compared to LVST and the control group (p = 0.047). Even though they present the same neuromuscular and morphological adaptations in postmenopausal women, the HVST is more effective than LVST in improving the lipid profile of postmenopausal woman, and can be considered as an ideal program of intervention to reverse changes in lipid metabolism commonly found in this group.

Contribution of strength characteristics to change of direction and agility performance in female basketball athletes.

Research has often examined the relationship between 1 or 2 measures of strength and change of direction (COD) ability reporting inconsistent relationships to performance. These inconsistencies may be the result of the strength assessment used and the assumption that 1 measure of strength can represent all "types" of strength required during a COD task. Therefore the purpose of this study was to determine the relationship between several lower-body strength and power measures, COD, and agility performance. Twelve (n = 12) elite female basketball athletes completed a maximal dynamic back squat, isometric midthigh pull, eccentric and concentric only back squat, and a countermovement jump, followed by 2 COD tests (505 and T-test) and a reactive agility test. Pearson product-moment correlation and stepwise regression analysis were performed on all variables. The percentage contribution of each strength measure to an athletes total strength score was also determined. Our results demonstrated that both COD tests were significantly correlated to maximal dynamic, isometric, concentric, and eccentric strength (r = -0.79 to -0.89), with eccentric strength identified as the sole predictor of COD performance. Agility performance did not correlate with any measure of strength (r = -0.08 to -0.36), whereas lower-body power demonstrated no correlation to either agility or COD performance (r = -0.19 to -0.46). These findings demonstrate the importance of multiple strength components for COD ability, highlighting eccentric strength as a deterministic factor of COD performance. Coaches should aim to develop a well-rounded strength base in athletes; ensuring eccentric strength is developed as effectively as the often-emphasized concentric or overall dynamic strength capacity.