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Abstract

The aim of this study was to examine the effect of two different lower body strength training schemes on upper body adaptations to resistance training. Twenty resistance-trained males (4.25+/-1.6 y of experience) were randomly assigned to either a high-intensity (HI; n=9; age=24.9+/-2.9 y; body mass=88.7+/-17.2 kg; height=177.0+/-5.6 cm) or a mixed high-volume and high-intensity resistance training program (MP; n=11; age=26.0+/-4.7 y; body mass=82.8+/-9.1 kg; height=177.54+/-5.9 cm). HI group followed a high-intensity training for both upper and lower body (4-5 reps at 88-90% of 1-RM), while the MP group performed high-volume training sessions focused on muscle hypertrophy for lower body (10-12 reps at 65-70% of 1-RM) and a high-intensity protocol for the upper body. Maximal strength and power testing occurred before and after the 6-week training program. Analysis of covariance was used to compare performance measures between the groups. Greater increases in MP groups compare to HI group were observed for bench press 1-RM (p = 0.007), bench press power at 50 % of 1-RM (p = 0.011) and for AMA (p = 0.046). Significant difference between the two groups at post-test were also observed for fat mass (p = 0.009). Results indicated that training programs focused on lower body muscle hypertrophy and maximal strength for upper body, can stimulate greater strength and power gains in the upper body compared to high-intensity resistance training programs for both the upper and lower body.

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... While GH is anabolic during childhood and puberty (1), its relevance for muscle tissue growth in adults is debated (43,46). Yet, the importance of GH as an anabolic hormone is claimed by some (2,15,23,24,29,36). Synergistic effects of GH on testosterone-mediated protein synthesis (42), and facilitated effects on muscle repair and remodeling is suggested (37). ...
... Others argue that training effects are optimal when muscle protein synthesis for the targeted muscle is increased, that is, once training of the upper-body has been performed (35). Several studies have reported potentiating effects (greater gains in strength and/or hypertrophy) of lower-body training prior to upper-body strength and hypertrophy training (2,15,27,29). Ronnestad, Nygaard, and Raastad (36) reported greater 1-RM and cross-sectional area (CSA) increases in the bicep brachii muscle for the group when leg training is performed before arm training. Meanwhile, some studies report no enhancing effect with exposure of loaded muscles to exercise-induced elevations in anabolic hormones (44,45). ...
... Training protocols designed to manipulate circulating endogenous GH and testosterone via leg exercises using high-volume training with short inter-set rest can induce a distal transfer effect (2,23,27,29). Although, the relevance of short inter-set rest has more recently become challenged (39). Such regimens are suggested to result in superior strength training adaptions and greater strength gains, with or without an additive increase in muscle mass. ...
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Resistance exercise has been shown to induce an acute hormonal response. The purpose of this study was to examine upper-body adaptations and the endocrine response to strength training in men and women when subjected to two different types of lower-body resistance training protocols. Nine males and eight females were assigned to either a Heavy Load (HL) (N = 10) or Mixed Load (ML) (N = 7) training routine three times per week for ten weeks. The HL-group executed low-volume, high-load resistance exercise for both lower and upper-body (4-6 reps at 80-90% of one repetition maximum (1-RM), three-minute inter-set rest). The ML-group performed the HL-protocol for the upper-body, but a high-volume, moderate-load protocol for the lower body (10-15 reps at 60-70% of 1-RM, one-minute inter-set rest). Volume load, 1-RM strength and hormonal measurements were analyzed by repeated-measures linear mixed models. Both groups increased their 1-RM in all assessments (p < 0.01) with no significant difference between groups at any time. Growth hormone (GH), testosterone and bioavailable testosterone (T/SHBG) increased in both groups during a standardized exercise session (p < 0.01) with ML having a greater increase in GH. The notion that acute elevations in anabolic hormones is important for muscle strength adaptation cannot be supported by the present study.
... Strength improvement in skeletal muscle can be activated not only by the trained limb, but also by the contralateral, untrained limb [1,2]. This phenomenon is usually defined as "cross-education" or "cross-transfer effect" [3,4]. It is well established that kind of motor learning induced by neural plasticity of the motor cortex, premotor complex, and cerebellum associated with the neural adaptations is related to the cross transfer [3,5,6]. ...
... This phenomenon is usually defined as "cross-education" or "cross-transfer effect" [3,4]. It is well established that kind of motor learning induced by neural plasticity of the motor cortex, premotor complex, and cerebellum associated with the neural adaptations is related to the cross transfer [3,5,6]. A transfer effect has also been observed between the lower and upper body. ...
... A transfer effect has also been observed between the lower and upper body. Bartolomei et al. (2018) suggested that combination of high volume and high intensity resistance training for lower-body exercises and upper-body exercises, respectively, can provide a greater stimulus in strength and power gains in the upper body [3]. Others have also reported this greater strength gains in upper body while lower-body strength training was added to the upper-body training program [7,8]. ...
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Background The purpose of this study is to investigate the Bottom–Up Rise Strength Transfer (BURST) induced by massed vs. distributed-rehabilitative exercise training. Methods Participants were randomly allocated to one of the 12 weeks massed (MRT) vs. distributed-(DRT) rehabilitative exercise training (performing lower limb proprioceptive, balance, agility, and resistance exercise) group or no-intervention group (Control). The upper and lower limb strength assessment was recorded at baseline (pre), 8 weeks (mid), and 12 weeks (post). Results The net right hand MVC force increased after 12 weeks of DRT (58.3%). The net left hand MVC force increased after 12 weeks of both DRT and MRT (44.0% & 33.9% respectively). The BURST effect induced by DRT was significantly larger than MRT (in right hand: 45.1% & in left hand 33.4%). Conclusions This is the first study investigating in a between-subject design the BURST effect of massed vs. distributed-rehabilitative training. The result showed middle-aged women can develop their upper limbs strength by performing both the DRT and MRT in their lower limbs. Lower body distributed resistance training, however, can provide a significantly greater stimulus for increasing the BURST in middle-aged women.
... Agility can be defined as the quickness by which an athlete can change direction and includes complete decelerations and quick accelerations [3]. Despite the importance of this element in FH, interestingly, no significant differences in agility and sprint performances were detected between division I and division II Italian players [4]. ...
... Anthropometric evaluations and muscle ultrasound measurements were performed prior to the performance assessments. A standardized warm-up [4] consisting of 5 min jogging, 10 body weight squats, 10 body weight walking lunges, 10 dynamic walking hamstring stretches, 10 dynamic walking quadriceps stretches, and 10 body weight push-ups was performed before the performance evaluations. Subsequently, each participant was tested for maximal isometric force, agility and sprinting performance. ...
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Muscle architecture has been proposed as one of the most important determinants of muscle strength and power performance. The purpose of the present investigation was to correlate the muscle architecture with power, agility and maximal strength in Italian division I Field Hockey (FH) players. Twenty players (age = 25.4 ± 5.2 y; body mass = 78.5 ± 9.0 kg; body height = 179.6 ± 7.8 cm) were assessed for body composition, agility, sprint and maximal isometric force in squat (ISQ). The pro-agility test (PRO) and 30-m sprint (SPRINT) were used for agility and speed assessments, respectively. In addition, the pennation angle (PA), fascicle length (FL) and muscle thickness (MT) of the vastus lateralis were assessed via B-mode ultrasound. Large positive correlations were found between PRO and both PA and MT (r = 0.62; p = 0.006 and r = 0.51; p = 0.032, respectively). Moreover, SPRINT was positively correlated with PA and negatively correlated with FL (r = 0.50, p = 0.046; and r = −0.50; p = 0.034, respectively). Large positive correlations were also detected between body fat and both PRO and SPRINT (r = 0.58; p = 0.012 and r = 0.61; p = 0.009, respectively), indicating detrimental effects of the body fat on specific performances. The present findings showed the existence of large relationships between the muscle architecture of the vastus lateralis and physical characteristics related to elite performance in FH. Low PA and long FL of the vastus lateralis appear important parameters for agility and sprint performances.
... It is well known that heavy resistance training can result in significant skeletal muscle hypertrophy and in maximal strength and power improvements (Bartolomei et al., 2018). The use of eccentric training, characterized by a greater external load applied during the eccentric phase of the lift, and removed before the concentric phase, has been shown to provide an advantage in strength adaptations compared to traditional loading paradigms (Walker et al., 2016). ...
... Prior to 1-RM bench press testing, participants performed a standardized warm-up described in previous studies (Bartolomei and Hoffman, 2018). The 1-RM test for the bench press was performed on a Smith machine using methods previously defined by Hoffman (2014). ...
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The purpose of this study was to compare the physiological responses of a single bout of an eccentric accentuated bench press protocol (120% of 1RM in the eccentric phase/80% in the concentric phase; [120/80]) versus a regular high-intensity exercise protocol (80%/80%; [80/80]) in resistance-trained men. Eleven men (age = 25.6 ± 3.9 y; body mass = 84.6 ± 11.2 kg; body height = 176.4 ± 3.9 cm) with 6.3 ± 3.4 y of resistance training experience performed each protocol in counterbalanced, randomized order. Isometric, isokinetic and ballistic tests were performed at the bench press (IBPF, ISOK and BTP, respectively) at baseline (BL), 15-min (15P), 24-h (24P), and 48-h (48P) post-exercise for each testing session. In addition, muscle thickness of the pectoralis major (PecMT) was measured at the same timepoints via ultrasound. Significantly greater reductions in BTP (p < 0.001), peak force during both ISOK (p = 0.005) and IBPF (p = 0.006) at 15P were detected in 120/80 compared to 80/80. BTP was still significantly (p = 0.009) impaired at 48P following the 120/80 protocol, while no differences were noted following 80/80. PecMt was significantly elevated following both 120/80 and 80/80 (p < 0.05) at 15P, but significant differences between the trials were present at 15P and 24P (p = 0.005 and p = 0.008, respectively). Results indicated that heavy eccentric loading during the bench press exercise caused greater performance deficits than a bout of traditionally loaded high intensity resistance exercise. Power performance appears to be more influenced by the 120/80 protocol than isometric peak force. Eccentrically loaded exercise sessions should be separated by at least 48 hours to obtain a complete recovery of the initial muscle morphology and performance.
... Nevertheless, current evidence is mainly limited to full body programs or programs performed only with one area of the body. Recent clinical trials have examined the effects of strength training focused on the lower or upper body, suggesting that it may lead to improvements in strength in the body area that was not involved in performing the exercises [16]. In other studies, the effects of performing targeted strength exercise on markers related to muscle mass [17] or cellular stress [18] have also been examined. ...
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Purpose To compare the effects of upper versus the lower-body resistance exercise on cognitive and physical functions of institutionalized older people. Methods This was a non-randomized multi-center comparative and crossover study (clincialtrials.gov code NCT03831373). Two experimental groups performed a 12-week intervention of resistance exercises with low-intensity elastic bands, one program focused on exercises of the upper body ( n = 20, mean age 87.6 ± 6.4 years, 75% women) and the other on the lower body ( n = 29, mean age 81.4 ± 7.7 years, 55% women). Following 12 weeks of detraining, the groups performed the other intervention. After another 12 weeks, a follow-up assessment was carried. The control group ( n = 19, mean age 81.3 ± 9.5, 68% women) performed a full body stretching exercise program in both phases. Before and after each period, cognitive and physical function was assessed by standardized test (Mini-Mental State Examination, Trail Making test and Phototest; Timed Up and Go, Back Scratch, Chair Sit and Reach and had grip strength, respectively). Intention-to-treat and per-protocol analyses were carried. Results After the first intervention, significant improvements ( p < 0.05) were observed in the cognitive function in both experimental groups, and in the hand grip strength in the group that performed lower-body exercise. After the second phase, all groups showed improvements in lower-body and shoulder flexibility and a significant worsening in hand grip strength. The lower-body exercise group showed a worsening in cognitive function, and the upper-body group in functional mobility and dynamic balance. Conclusions Resistance exercise with elastic bands showed beneficial effects on cognitive function and functional independence in institutionalized older adults. While upper body exercises seemed to be more effective on cognitive function, lower limb exercises showed better results on physical function parameters.
... The output variables of the articles were defined as follows. Fat-free mass (FMM) was calculated as "all that is not fat", subtracting fat weight from body weight, or when the measurements were obtained by dual X-ray absorptiometry was calculated as lean tissue plus bone mineral content [12]. Lean muscle mass (LMM), lean mass, lean body mass, bone-free lean body mass or mineral-free lean mass was calculated as the fat-free mass minus the bone mineral content (DXA) or as fat-free mass minus the estimated weight [13] of the live bone by the equation of Heymsfield et al. [14]. ...
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We performed a systematic review and meta-analysis to study all published clinical trial interventions, determined the magnitude of whole-body hypertrophy in humans (healthy males) and observed the individual responsibility of each variable in muscle growth after resistance training (RT). Searches were conducted in PubMed, Web of Science and the Cochrane Library from database inception until 10 May 2018 for original articles assessing the effects of RT on muscle size after interventions of more than 2 weeks of duration. Specifically, we obtain the variables fat-free mass (FMM), lean muscle mass (LMM) and skeletal muscle mass (SMM). The effects on outcomes were expressed as mean differences (MD) and a random-effects meta-analysis and meta-regressions determined covariates (age, weight, height, durations in weeks…) to explore the moderate effect related to the participants and characteristics of training. One hundred and eleven studies (158 groups, 1927 participants) reported on the effects of RT for muscle mass. RT significantly increased muscle mass (FFM+LMM+SMM; Δ1.53 kg; 95% CI [1.30, 1.76], p < 0.001; I2 = 0%, p = 1.00). Considering the overall effects of the meta-regression, and taking into account the participants' characteristics, none of the studied covariates explained any effect on changes in muscle mass. Regarding the training characteristics, the only significant variable that explained the variance of the hypertrophy was the sets per workout, showing a significant negative interaction (MD; estimate: 1.85, 95% CI [1.45, 2.25], p < 0.001; moderator: -0.03 95% CI [−0.05, −0.001] p = 0.04). In conclusion, RT has a significant effect on the improvement of hypertrophy (~1.5 kg). The excessive sets per workout affects negatively the muscle mass gain.
... It is worth mentioning that the published studies related to both cross-education and cross-transfer between lower and upper body were mainly conducted in young subjects (Hansen et al., 2001;Munn et al., 2004;Hendy and Lamon, 2017;Bartolomei et al., 2018). More recently, Ben Othman et al. (2018) discussed cross education phenomena also in developmental stage. ...
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The phenomenon of strength gain is highly relevant for sarcopenia and clinical aspect linked to aging. Recent advancements drive the interest toward the exercise-related cross-talk between distant tissues. We demonstrated the cross-talk between lower and upper limbs, we named the Bottom-Up Rise Strength Transfer (BURST), mainly linked to endurance training. In our opinion, this effect can be mainly related to systemic factors, likely circulating myokines and extracellular vesicles (recently defined in terms of “exerkines” and “exersomes”) whit an eventual concomitant reduction of a sub-clinical chronic inflammation. The neuronal mechanisms, even if to our sight less likely involved in this adaptation, need to be deeply investigated. Further studies are needed to better characterize the exercise-related BURST, concerning the specificity of different protocols and the underlying physiological mechanisms.
... 13 Bunun yanında 1TM bench press her düzeydeki sporcu, genç, yaşlı, obez ve fiziksel olarak aktif birey gibi çok değişik popülasyonda üst ekstremite maksimal dinamik kuvvetin değerlendirilmesinde yaygın olarak kullanılmaktadır. [14][15][16][17][18] Buradan hareketle bu çalışmanın amacı 1TM bench press kuvvetinin kestirilmesinde kullanılan formüllerin rekreatif olarak aktif erkek bireylerde geçerliğini belirlemektir. ...
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Objective: The aim of this study was to determine the validity of the formulas used to estimate 1 repetition maximum (1RM) strength on bench press in young men. Material and Methods: 1RM strength of 27 young men (22.7±2.6 years) was determined in bench press. Following 48 hours rest, participants performed bench press repetitions to failure (RTF) at a load of 75-90% 1RM. Their 1RM bench press strength was estimated through 16 estimation formulas (11 linear and 5 exponential), by using a load of 75-90% of 1RM and RTF. Validity of the estimation formulas was assessed using repeated measures ANOVA and Lin’s the concordance correlation coefficient (ρc). Results revealed that actual 1RM bench press strength and estimated 1RM strength from 10 formulas out of 16 showed no significant difference. Results: Concordance correlation coefficient was found “high” between estimated 1RM strength from 10 formulas and actual 1RM strength (ρc≥0.962). Concordance correlation coefficient ρc was ‘’low’’ and ‘’moderate’’ for formulas estimated 1RM “higher” and “lower”. Conclusion: The results of this study showed that 10 of the 16 formulas available in literature can be used accurately and valid determination of 1RM strength in bench press in young men.
... Ojo and Oladipo (2018) reported that body weight resistance training prompts greater performance improvements in arm power ability. Though, Bartolomeil, Hoffman, Stout and Merni, (2016) reported no significant improvement of arm power after a six ...
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The advent in technology makes people to spend less time doing physical work while incidence of sedentariness and musculoskeletal disorders increases rapidly. Since schools students enjoy screen-based activities which is sedentariness, free weights training have the potentials of accommodating such personalities while training the body. Physical performance variables include: arm strength (AS), arm power (AP) and lower back flexibility (LBF) and are required in carrying out daily activities. The study adopted the frequency, intensity, time and type (FITT) principles of fitness training. The pretest-posttest control group quasi experimental design was used. Eighty participants (forty males and forty females) selected from two secondary schools in Ondo town were randomly assigned to free weights training (FWT) and control groups. The treatment lasted for twelve (12) weeks. Data were analysed using descriptive statistics of frequency count and percentages as well Analysis of Covariance to test the hypotheses at .05 level of significance. There were significant main effects of treatment on the physical fitness variables of AS (F (1,77) =136.526; P<.05; η 2 =.639), AP(F(1,77)= 178.091; P<.05; η 2 =.698) and LBF (F(1,77)= 294.186; P<.05; η 2 =.793). The FWT was potent at improving physical fitness variables; AS, AP and F of secondary school students. Therefore, the youth should engage in FWT for health benefits and improved physical fitness regardless of their stature.
... A standardized warm-up (Bartolomei et al., 2018a) consisting of 5 min jogging, 10 body weight squats, 10 body weight walking lunges, 10 dynamic walking hamstring stretches, 10 dynamic walking quadriceps stretches and 10 body weight push-ups was performed before the evaluations. All the assessments were supervised by qualified investigators. ...
Article
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The aim of this study was to compare the effects of two resistance training programs including either a deadlift or a parallel squat on lower body maximal strength and power in resistance trained males. Twentyfive resistance trained men were randomly assigned to a deadlift group (DE; n = 14; age = 24.3 ± 4.1 y; body mass = 84.8 ± 14.2 kg; body height = 180.3 ± 6.8 cm) or to a squat group (SQ; n = 11; age = 22.3 ± 1.6 y; body mass = 83.0 ± 13.6 kg; body height 179.9 ± 6.1 cm). Both groups trained 3 times per week for 6 weeks. The deadlift and the squat were the only lower body maximal strength exercises performed by DE and SQ groups, respectively, while both training programs included jumps. A significantly (p = 0.017) greater increase in deadlift 1RM was observed in the DE compared to the SQ group, while the SQ group obtained a significantly (p = 0.049) greater increase in squat 1RM. A significant increase in jump performance (p = 0.010), without significant interactions between groups (p = 0.552), was observed in both groups. Three participants of the DE group developed lower back pain and were excluded from the study. Results indicate that both the squat and the deadlift can result in similar improvement in lower body maximal strength and jump performance and can be successfully included in strength training programs. The incidence of back pain in the DE group may suggest a marked stress of this exercise on the lower back. Proper technique should be used to minimize the risk of injury, especially when the deadlift is performed. Keywords: resistance training, jump performance, strength exercises.
... This non-localized effect may induce an increase in the performance of the lower body when the upper body muscles have been exercised, and vice versa. Chronic influences of different lower body resistance exercise protocols on the upper body strength adaptations have been previously reported [7]. Furthermore, some authors investigated the acute non-localized effects of both upper and lower body resistance exercises. ...
Article
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The aim of the present investigation was to compare the acute non-localized post-activation performance enhancement (PAPE) of an exercise protocol involving either the upper or the lower body muscles. Twenty-four resistance trained men participated in the present study and were randomly assigned to an upper body (UB) or to a lower body (LB) group. Both groups tested for upper and lower body power (bench press throw (BPT) and countermovement jump power (CMJP) tests). Participants in the UB group were tested pre and post a high-intensity (HI) and a high-power (POW) bench press protocol while participants in the LB group performed a HI squat and a jump session (POW). A significant group x time interaction was found for CMJP in HI (p = 0.012). Post hoc tests revealed that CMJP was elevated in UB group only (+1.6%; p=0.025). No other significant interactions were detected. Results of this study indicate that a non-localized PAPE on the lower body may be induced by a HI bench press protocol while a HI squat protocol may not increase upper body power. In particular, the squat protocol performed in the present study (5 sets of 1 rep) may be too demanding to produce a non-localized PAPE.
... All measurements were performed by the same qualified investigators using a Harpender Skinfold Caliper (Harpenden, British Indicators, West Sussex, UK). Prior to the strength and power evaluations, the participants performed a standardized warm-up consisting of five min on a cycle ergometer against a light resistance, 10 body weight squats, 10 body weight walking lunges, 10 dynamic walking hamstring stretches, 10 dynamic walking quadriceps stretches, and 5 push-ups [15]. Following the warm-up, the participants performed the bench press 1RM test, using the methods previously described by Bartolomei et al. [16]. ...
Article
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The purpose of the present investigation was to compare the acute responses on muscle architecture, electromechanical delay (EMD) and performance following a high volume (HV: 5 sets of 10 reps at 70% of 1 repetition maximum (1RM)) and a high intensity (HI: 5 sets of 3 reps at 90% of 1RM) bench press protocol in women. Eleven recreationally trained women (age = 23.3 1.8 y; � body weight = 59.7 6.0 kg; height = 164.0 6.3 cm) performed each protocol in a counterbalanced � � randomized order. Muscle thickness of pectoral (PEC MT) and triceps muscles (TR MT) were collected prior to and 15 min post each trial. In addition, EMD of pectoral (PEC EMD) and triceps (TR EMD) muscles were calculated during isometric bench press maximum force tests performed at the same timepoints (IBPF). Significantly greater increases in PEC MT (p < 0.001) and TR MT (p < 0.001) were detected following HV compared to HI. PEC EMD showed a significantly greater increase following HV compared to HI (p = 0.039). Results of the present study indicate that the HV bench press protocol results in greater acute morphological and neuromuscular changes compared to a HI protocol in women. Evaluations of muscle morphology and electromechanical delay appear more sensitive to fatigue than maximum isometric force assessments.
... However, the extent of cross-education effects on heterologous muscles has not been fully elucidated yet. Throughout literature, several authors have reported an enhancement in ipsilateral elbow flexors strength when an upper-body coadjutant training was added to a lower-body RT program [16][17][18]. Lately, Ben Othman et al. [19], after an 8-week training program (24 sessions) involving the unilateral leg press exercise, reported similar effects on strength in both contralateral non-trained homologous muscles and heterologous (elbow flexors) muscles in youth participants. In addition, the greater magnitudes of changes in the contralateral non-trained leg and non-trained arm were shown after training with higher intensities compared to lower intensities [19]. ...
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Background and Objectives: To investigate the effects of unilateral accentuated eccentric loading (AEL) on changes in lean mass and function of leg trained (TL) and ipsilateral non-trained arm (NTA) in young men and women. Materials and Methods: In a prospective trial, 69 Physically active university students (20.2 ± 2.2 years) were randomly placed into a training group (n = 46; 27 men, 19 women) or a control group without training (n = 23; 13 men, 10 women). Participants in the training group performed unilateral AEL in the leg press exercise of the dominant leg twice a week for 10 weeks. An electric motor device-generated isotonic resistance at different intensities for both concentric (30% of 1-RM) and eccentric contractions (105% of 1-RM). Changes in thigh and arm lean tissue mass, unilateral leg press and unilateral elbow flexion maximal concentric (1-RM) and isometric strength (MVIC), and unilateral muscle power at 40, 60, and 80% 1-RM for both leg press and elbow flexion exercises before and after intervention were compared between groups, between sexes and between TL and NTA. Results: Both men and women in the training group showed increases (p < 0.05) in lean tissue mass, 1-RM, MVIC, and muscle power for TL. In NTA, 1-RM, MVIC, and muscle power increased without significant differences between sexes, but neither in men nor women changes in lean tissue mass were observed. In addition, men showed greater changes in TL, but changes in NTA were similar between sexes. No gains in any variable were found for the control group. Conclusions: AEL protocol produced similar neuromuscular changes in TL and ipsilateral NTA, which suggests that strong ipsilateral lower-to-upper limb cross-transfer effects were induced by the eccentric-overload training. However, early ipsilateral increases in muscle force and power were not associated with lean mass gains. Both men and women experienced similar changes in NTA; however, men showed greater changes in TL.
... However, the extent of cross-education effects on heterologous muscles has not been fully elucidated yet. Throughout literature, several authors have reported an enhancement in ipsilateral elbow flexors strength when an upper-body coadjutant training was added to a lower-body RT program [16][17][18]. Lately, Ben Othman et al. [19], after an 8-week training program (24 sessions) involving the unilateral leg press exercise, reported similar effects on strength in both contralateral non-trained homologous muscles and heterologous (elbow flexors) muscles in youth participants. In addition, the greater magnitudes of changes in the contralateral non-trained leg and non-trained arm were shown after training with higher intensities compared to lower intensities [19]. ...
Article
Bartolomei, S, Rovai, C, Lanzoni, IM, and di Michele, R. Relationships between muscle architecture, deadlift performance, and maximal isometric force produced at the midthigh and midshin pull in resistance-trained individuals. J Strength Cond Res XX(X): 000-000, 2019-The aim of this study was to investigate the relationships between muscle architecture, lower-body power, and maximal isometric force produced at midthigh pull (MTP), and at midshin pull (MSP). Twenty experienced resistance-trained men (age = 25.5 ± 3.2 years; body mass = 86.9 ± 12.4 kg; body height = 178.0 ± 5.3 cm) were tested for deadlift 1 repetition maximum (1RM), countermovement jump (CMJ), peak force (PF), and rate of force development (pRFD20) produced at isometric MTP and isometric MSP. Subjects were also assessed for architecture of vastus lateralis (VL), and physiological muscle thickness, pennation angle, and fascicle length (FL) were measured. Pearson's correlation coefficients were calculated to assess the relationships between variables. In addition, differences between MTP and MSP were assessed using paired-sample t-tests. A significant (p < 0.05) difference was detected on the correlation between deadlift 1RM and MSP (r = 0.78; p < 0.001) compared with MTP (r = 0.55; p = 0.012). Moderate correlations were observed between MSP PF and VLFL (r = 0.55; p = 0.011). Midshin pull pRFD20 was the only parameter significantly correlated with CMJ (r = 0.50; p = 0.048). Significantly higher PF and pRFD20 were recorded in MTP compared with MSP (p = 0.007 and p = 0.003, respectively). The present results show that force produced from the floor position may be more important than force produced from a position that mimics the second pull of the clean for deadlift and vertical jump performances. Coaches and scientific investigators should consider using MSP to assess isometric PF using a test correlated with both muscle architecture and dynamic performances.
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Purpose Low-load venous blood flow restriction resistance training (RT + BFR) has been demonstrated to increase muscle strength to a greater degree than low-load non-BFR resistance training (RT) during isotonic training, but no previous investigations have examined RT + BFR versus RT during isokinetic training. The purpose of the present study was to examine the effects of 4 weeks of isokinetic low-load RT + BFR versus low-load RT on indices of muscle strength, muscle size, and neural adaptations. Methods Thirty women (mean ± SD; 22 ± 2 years) participated in this investigation and were randomly assigned to 4 weeks of either RT + BFR (n = 10), RT (n = 10), or control (n = 10) group. Resistance training consisted of 75 reciprocal forearm flexion–extension isokinetic muscle actions of the forearm flexors performed at a velocity of 120°s⁻¹. Results Concentric peak torque increased to a greater extent for RT + BFR after 4 weeks (36.9%) compared to RT (25.8%), but there were similar increases in isometric torque (23.3–42.1%). For both RT + BFR and RT, there were similar increases in muscle cross-sectional area and muscle thickness of the biceps brachii after 2 weeks (11.3–14.3% and 12.4–12.9%, respectively) and 4 weeks (18.7–21.9% and 19.0–20.0%, respectively). There were similar increases in mechanomyographic amplitude, mechanomyographic mean power frequency, and electromyographic mean power frequency, but no changes in electromyographic amplitude for all conditions (including control). Conclusions These findings indicated that low-load RT + BFR elicited greater increases in concentric strength than low-load RT, but elicited comparable increases in isometric strength and muscle size. There were also no differences in any of the EMG and MMG responses among conditions.
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Resistance exercise paradigms are often divided into high volume (HV) or high intensity (HI) protocols, however, it is unknown whether these protocols differentially stimulate mTORC1 signaling. The purpose of this study was to examine mTORC1 signaling in conjunction with circulating hormone concentrations following a typical HV and HI lower-body resistance exercise protocol. Ten resistance-trained men (24.7 ± 3.4 years; 90.1 ± 11.3 kg; 176.0 ± 4.9 cm) performed each resistance exercise protocol in a random, counterbalanced order. Blood samples were obtained at baseline (BL), immediately (IP), 30 min (30P), 1 h (1H), 2 h (2H), and 5 h (5H) postexercise. Fine needle muscle biopsies were completed at BL, 1H, and 5H. Electromyography of the vastus lateralis was also recorded during each protocol. HV and HI produced a similar magnitude of muscle activation across sets. Myoglobin and lactate dehydrogenase concentrations were significantly greater following HI compared to HV (P = 0.01-0.02), whereas the lactate response was significantly higher following HV compared to HI (P = 0.003). The growth hormone, cortisol, and insulin responses were significantly greater following HV compared to HI (P = 0.0001-0.04). No significant differences between protocols were observed for the IGF-1 or testosterone response. Intramuscular anabolic signaling analysis revealed a significantly greater (P = 0.03) phosphorylation of IGF-1 receptor at 1H following HV compared to HI. Phosphorylation status of all other signaling proteins including mTOR, p70S6k, and RPS6 were not significantly different between trials. Despite significant differences in markers of muscle damage and the endocrine response following HV and HI, both protocols appeared to elicit similar mTORC1 activation in resistance-trained men. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.
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In evolutionary terms, GH and intracellular STAT 5 signaling is a very old regulatory system. Whereas insulin dominates periprandially, GH may be viewed as the primary anabolic hormone during stress and fasting. GH exerts anabolic effects directly and through stimulation of IGF-I, insulin, and free fatty acids (FFA). When subjects are well nourished, the GH-induced stimulation of IGF-I and insulin is important for anabolic storage and growth of lean body mass (LBM), adipose tissue, and glycogen reserves. During fasting and other catabolic states, GH predominantly stimulates the release and oxidation of FFA, which leads to decreased glucose and protein oxidation and preservation of LBM and glycogen stores. The most prominent metabolic effect of GH is a marked increase in lipolysis and FFA levels. In the basal state, the effects of GH on protein metabolism are modest and include increased protein synthesis and decreased breakdown at the whole body level and in muscle together with decreased amino acid degradation/oxidation and decreased hepatic urea formation. During fasting and stress, the effects of GH on protein metabolism become more pronounced; lack of GH during fasting increases protein loss and urea production rates by approximately 50%, with a similar increase in muscle protein breakdown. GH is a counterregulatory hormone that antagonizes the hepatic and peripheral effects of insulin on glucose metabolism via mechanisms involving the concomitant increase in FFA flux and uptake. This ability of GH to induce insulin resistance is significant for the defense against hypoglycemia, for the development of "stress" diabetes during fasting and inflammatory illness, and perhaps for the "Dawn" phenomenon (the increase in insulin requirements in the early morning hours). Adult patients with GH deficiency are insulin resistant-probably related to increased adiposity, reduced LBM, and impaired physical performance-which temporarily worsens when GH treatment is initiated. Conversely, despite increased LBM and decreased fat mass, patients with acromegaly are consistently insulin resistant and become more sensitive after appropriate treatment.
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It has long been believed that resistance training is accompanied by changes within the nervous system that play an important role in the development of strength. Many elements of the nervous system exhibit the potential for adaptation in response to resistance training, including supraspinal centres, descending neural tracts, spinal circuitry and the motor end plate connections between motoneurons and muscle fibres. Yet the specific sites of adaptation along the neuraxis have seldom been identified experimentally, and much of the evidence for neural adaptations following resistance training remains indirect. As a consequence of this current lack of knowledge, there exists uncertainty regarding the manner in which resistance training impacts upon the control and execution of functional movements. We aim to demonstrate that resistance training is likely to cause adaptations to many neural elements that are involved in the control of movement, and is therefore likely to affect movement execution during a wide range of tasks. We review a small number of experiments that provide evidence that resistance training affects the way in which muscles that have been engaged during training are recruited during related movement tasks. The concepts addressed in this article represent an important new approach to research on the effects of resistance training. They are also of considerable practical importance, since most individuals perform resistance training in the expectation that it will enhance their performance in related functional tasks.
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It is generally accepted that neural factors play an important role in muscle strength gains. This article reviews the neural adaptations in strength, with the goal of laying the foundations for practical applications in sports medicine and rehabilitation. An increase in muscular strength without noticeable hypertrophy is the first line of evidence for neural involvement in acquisition of muscular strength. The use of surface electromyographic (SEMG) techniques reveal that strength gains in the early phase of a training regimen are associated with an increase in the amplitude of SEMG activity. This has been interpreted as an increase in neural drive, which denotes the magnitude of efferent neural output from the CNS to active muscle fibres. However, SEMG activity is a global measure of muscle activity. Underlying alterations in SEMG activity are changes in motor unit firing patterns as measured by indwelling (wire or needle) electrodes. Some studies have reported a transient increase in motor unit firing rate. Training-related increases in the rate of tension development have also been linked with an increased probability of doublet firing in individual motor units. A doublet is a very short interspike interval in a motor unit train, and usually occurs at the onset of a muscular contraction. Motor unit synchronisation is another possible mechanism for increases in muscle strength, but has yet to be definitely demonstrated. There are several lines of evidence for central control of training-related adaptation to resistive exercise. Mental practice using imagined contractions has been shown to increase the excitability of the cortical areas involved in movement and motion planning. However, training using imagined contractions is unlikely to be as effective as physical training, and it may be more applicable to rehabilitation. Retention of strength gains after dissipation of physiological effects demonstrates a strong practice effect. Bilateral contractions are associated with lower SEMG and strength compared with unilateral contractions of the same muscle group. SEMG magnitude is lower for eccentric contractions than for concentric contractions. However, resistive training can reverse these trends. The last line of evidence presented involves the notion that unilateral resistive exercise of a specific limb will also result in training effects in the unexercised contralateral limb (cross-transfer or cross-education). Peripheral involvement in training-related strength increases is much more uncertain. Changes in the sensory receptors (i.e. Golgi tendon organs) may lead to disinhibition and an increased expression of muscular force. Agonist muscle activity results in limb movement in the desired direction, while antagonist activity opposes that motion. Both decreases and increases in co-activation of the antagonist have been demonstrated. A reduction in antagonist co-activation would allow increased expression of agonist muscle force, while an increase in antagonist co-activation is important for maintaining the integrity of the joint. Thus far, it is not clear what the CNS will optimise: force production or joint integrity. The following recommendations are made by the authors based on the existing literature. Motor learning theory and imagined contractions should be incorporated into strength-training practice. Static contractions at greater muscle lengths will transfer across more joint angles. Submaximal eccentric contractions should be used when there are issues of muscle pain, detraining or limb immobilisation. The reversal of antagonists (antagonist-to-agonist) proprioceptive neuromuscular facilitation contraction pattern would be useful to increase the rate of tension development in older adults, thus serving as an important prophylactic in preventing falls. When evaluating the neural changes induced by strength training using EMG recording, antagonist EMG activity should always be measured and evaluated.
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If exercises are performed to increase muscle strength on one side of the body, voluntary strength can increase on the contralateral side. This effect, termed the contralateral strength training effect, is usually measured in homologous muscles. Although known for over a century, most studies have not been designed well enough to show a definitive transfer of strength that could not be explained by factors such as familiarity with the testing. However, an updated meta-analysis of 16 properly controlled studies (range 15-48 training sessions) shows that the size of the contralateral strength training effect is approximately 8% of initial strength or about half the increase in strength of the trained side. This estimate is similar to results of a large, randomized controlled study of training for the elbow flexors (contralateral effect of 7% initial strength or one-quarter of the effect on the trained side). This is likely to reflect increased motoneuron output rather than muscular adaptations, although most methods are insufficiently sensitive to detect small muscle contributions. Two classes of central mechanism are identified. One involves a "spillover" to the control system for the contralateral limb, and the other involves adaptations in the control system for the trained limb that can be accessed by the untrained limb. Cortical, subcortical and spinal levels are all likely to be involved in the "transfer," and none can be excluded with current data. Although the size of the effect is small and may not be clinically significant, study of the phenomenon provides insight into neural mechanisms associated with exercise and training.
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Neural adaptation following maximal strength training improves the ability to rapidly develop force. Unilateral strength training also leads to contralateral strength improvement, due to cross-over effects. However, adaptations in the rate of force development and peak force in the contralateral untrained arm after one-arm training have not been determined. Therefore, we aimed to detect contralateral effects of unilateral maximal strength training on rate of force development and peak force. Ten adult females enrolled in a 2-month strength training program focusing of maximal mobilization of force against near-maximal load in one arm, by attempting to move the given load as fast as possible. The other arm remained untrained. The training program did not induce any observable hypertrophy of any arms, as measured by anthropometry. Nevertheless, rate of force development improved in the trained arm during contractions against both submaximal and maximal loads by 40-60%. The untrained arm also improved rate of force development by the same magnitude. Peak force only improved during a maximal isometric contraction by 37% in the trained arm and 35% in the untrained arm. One repetition maximum improved by 79% in the trained arm and 9% in the untrained arm. Therefore, one-arm maximal strength training focusing on maximal mobilization of force increased rapid force development and one repetition maximal strength in the contralateral untrained arm. This suggests an increased central drive that also crosses over to the contralateral side.
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Arm muscle area (AMA, cm²) is currently calculated from triceps skinfold thickness (TSF, cm), and midarm circumference (MAC, cm). In assessing the accuracy of the current equation by comparison to AMA measured by computerized axial tomography, error in each of the four approximations made was found to result in a 20 to 25% overestimate of AMA. Two correctible error sources were: a 10 to 15% overestimation caused by assuming a circular midarm muscle compartment and a 5 to 10% overestimation due to inclusion of midarm cross-sectional bone area. Corrected AMA equations for men and women were respectively: [(MAC − π × TSF)²/4π] − 10, and [MAC − π × TSF)²/4π] − 6.5. With two additional study groups, the overall improved accuracy of the new equations was confirmed, although the average error for a given patient was 7 to 8%; the relationship between corrected AMA and total body muscle mass was established [muscle mass (kg) = (ht, cm²) (0.0264 + 0.0029 × corrected AMA)]; and the minimal range of corrected AMA values compatible with survival (9 to 11 cm²) was defined. Bedside estimates of undernutrition severity and prognosis can therefore be calculated from two simple measurements, TSF and MAC.
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The purpose of this study was to compare two different periodization models in strength and power athletes. Twenty-four experienced resistance trained man were randomly assigned to either a block periodization training program (BP; age = 24.2±3.1 years, body mass = 78.5±11.0 kg, height = 177.6±4.9 cm) or to a traditional periodization program (TP; age = 26.2±6.0 years; body mass = 80.5±13.3 kg, height = 179.2±4.6). Participants in both training programs performed four-training sessions per week. Each training program consisted of the same exercises and same volume of training (total resistance lifted per session). The difference between the groups was in the manipulation of training intensity within each training phase. Strength and power testing occurred before training (PRE) and following 15 weeks (POST) of training. Magnitude-based inferences were used to compare strength and power performance between the groups. Participants in BP were more likely (79.8%) to increase the area under the force-power curve than TP. Participants in BP also demonstrated a likely positive (92.76%) decrease in the load corresponding to maximal power at the bench press compared to TP group, and a possible improvement (∼ 60%) in maximal strength and power in the bench press. No significant changes were noted between groups in lower body strength or jump power performance following the 15 week training period. Results of this study indicate that BP may enhance upper-body power expression to a greater extent than TP with equal volume, however, no differences were detected for lower body performance and body composition measures.
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Forty college football players were tested at the conclusion of a winter conditioning program to determine the relationship among physical dimensions, seated shot put (SSP) performance, and bench press power (BPP). Absolute (AP) and relative (RP) bench press power outputs were determined with a specially designed bench press machine. AP used an absolute load of 61 kg for each subject, while RP used a load equal to 60% of the subject's l-RM bench press. The SSP was measured with a 4.5-kg indoor shot. Body composition and size were evaluated from skinfolds, segment circumferences, and limb lengths. Although SSP was significantly related to AP (r=0.51) and RP (r=0.66), removing the effect of differences in body mass reduced the correlation coefficients for both relationships (r=0.17 and 0.29, respectively). Removing the effect of LBM had the same effect on these relationships. Multiple regression analysis to predict AP selected SSP, body mass, and chest circumference (R=0.62). In predicting RP, the significant variables selected were flexed arm circumference and SSP (R=0.77). In both equations, SSP contributed less than 29% to the explained variance in BPP. Therefore it appears that the SSP is moderately related to both absolute and relative bench press power in college football players and may be greatly influenced by size and muscularity. (C) 1993 National Strength and Conditioning Association
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The purpose of this study was to compare serum growth hormone (GH), testosterone (T), cortisol (C), and whole blood lactate (L) responses to single set (1S) versus multiple set (3S) heavy-resistance exercise protocols. Eight recreationally weight-trained men completed two identical resistance exercise workouts (1S vs. 3S). Blood was obtained preexercise (PRE), immediately postexercise (OP), and 5 min (5P), 15 min (15P), 30 min (30P) and 60 min (60P) postexercise and was analyzed for GH, T, C, and L levels. For 1S and 3S, GH, L, and T significantly increased from PRE to OP and remained significantly elevated to 60P, except for 1S. For GH, T, and L, 3S showed significantly greater increases compared to 1S. For C, 3S and 1S were increased significantly from resting at OP, 5P, and 15P; 3S increased compared to 1S at 5P, 15P and 30P. Higher volumes of total work produce significantly greater increases in circulating anabolic hormones during the recovery phase following exercise.
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Unilateral strength training produces an increase in strength of the contralateral homologous muscle group. This process of strength transfer, known as cross education, is generally attributed to neural adaptations. It has been suggested that unilateral strength training of the free limb may assist in maintaining the functional capacity of an immobilised limb via cross education of strength, potentially enhancing recovery outcomes following injury. Therefore, the purpose of this review is to examine the impact of immobilisation, the mechanisms that may contribute to cross education, and possible implications for the application of unilateral training to maintain strength during immobilisation. Critical review of literature. Search of online databases. Immobilisation is well known for its detrimental effects on muscular function. Early reductions in strength outweigh atrophy, suggesting a neural contribution to strength loss, however direct evidence for the role of the central nervous system in this process is limited. Similarly, the precise neural mechanisms responsible for cross education strength transfer remain somewhat unknown. Two recent studies demonstrated that unilateral training of the free limb successfully maintained strength in the contralateral immobilised limb, although the role of the nervous system in this process was not quantified. Cross education provides a unique opportunity for enhancing rehabilitation following injury. By gaining an understanding of the neural adaptations occurring during immobilisation and cross education, future research can utilise the application of unilateral training in clinical musculoskeletal injury rehabilitation.
The purpose of this investigation was to study the effect of one-legged exercise on the strength, power and endurance of the contralateral leg. The performance of the knee extensor and flexor muscle of 20 healthy young adults (10 men and 10 women) was first tested by Cybex II+ and 340 dynamometers. Then 10 subjects were chosen at random to train using one leg three times a week for 7 weeks whilst the other 10 served as controls. During the 8th week, the tests were repeated. Both quadriceps and hamstring muscles of the trained subjects showed a cross-transfer effect from the trained limb to the untrained side. This concerned the strength and power, as well as endurance characteristics of these muscles. The average change in peak torque of the quadriceps muscle was + 19% (P<0.001) in the trained limb, + 11% (P<0.01) in the untrained limb and 0% in the control limbs. In hamstring muscles the changes were + 14% (P<0.01), + 5% and -1%, respectively. Concerning muscle endurance (work performed during the last 5 contractions in the 25-repetition test) the corresponding changes were + 15% (P<0.01), +7% (P<0.01), and -1% in quadriceps muscle, and + 17% (P<0.05), +7%, and -3% in hamstring muscles. The average strength benefit in the untrained limb was +36% (hamstring muscles) and +58% (quadriceps muscle) of that achieved in the trained limb. Untrained hamstring muscle showed better benefits in the endurance parameters than in strength or power parameters, while in the quadriceps muscle this effect was reversed. A positive relationship was observed between the changes (greater improvement in the trained limb resulted in greater improvement in the untrained limb) (hamstring muscles:r=0.83, P<0.001, quadriceps muscle:r=0.53, P<0.001). In endurance parameters, this relationship was almost linear while in the strength and power parameters the results were more in favour of a curvilinear relationship with limited benefit.
Twenty young men trained the right knee extensors and flexors on an isokinetic dynamometer three times weekly over a 10-week period. During each session, 10 men in the slow training group completed three sets of 8 maximal contractions at a rate of 1.05 rad s-1, whereas the other 10, the fast group, completed three sets of 20 contractions at a rate of 4.19 rad s-1. Subjects wer pre- and post-tested for peak torque and power on an isokinetic dynamometer at 1.05, 3.14, and 4.19 rad s-1. Proportions of muscle fibre-types and fibre cross-sectional areas were determined from biopsy specimens taken before and after training from the right vastus lateralis. When testing was conducted at 1.05 rad s-1, the slow group improved (P less than 0.05) peak torque by 24.5 N m (8.5%), but no change was noted for the fast group. Power increased (P less than 0.05) by 32.7 W (13.6%) in the slow group and 5.5 W (2.5%) in the fast. At 3.14 rad s-1, both groups increased (P less than 0.05) peak torque and power. At 4.19 rad s-1, the fast group increased (P less than 0.05) peak torque by 30.0 N m (19.7%), whereas no training effect was observed in the slow group. There was no significant change in power in either group at 4.19 rad s-1. No significant changes were observed over the 10-week training period in percentages of type I, IIa and IIb fibres, but both groups showed significant increases (P less than 0.05) in type I and IIa fibre areas.(ABSTRACT TRUNCATED AT 250 WORDS)
To investigate biochemical, histochemical and contractile properties associated with strength training and detraining, six adult males were studied during and after 10 weeks of dynamic strength training for the quadriceps muscle group of one leg, as well as during and after a subsequent 12 weeks of detraining. Peak torque outputs at the velocities tested (0-270 degrees X s-1) were increased (p less than 0.05) by 39-60% and 12-37% after training for the trained and untrained legs, respectively. No significant changes in peak torques were observed in six control subjects tested at the same times. Significant decreases in strength performance of the trained leg (16-21%) and untrained leg (10-15%) were observed only after 12 weeks of detraining. Training resulted in an increase (p less than 0.05) in the area of FTa (21%) and FTb (18%) fibres, while detraining was associated with a 12% decrease in FTb fibre cross-sectional area. However, fibre area changes were only noted in the trained leg. Neither training nor detaining had any significant effect on the specific activity of magnesium-activated myofibrillar ATPase or on the activities of enzymes of phosphagen, glycolytic or oxidative metabolism in serial muscle biopsy samples from both legs. In the absence of any changes in muscle enzyme activities and with only modest changes in FT fibre areas in the trained leg, the significant alterations in peak torque outputs with both legs suggest that neural adaptations play a prominent role in strength performance with training and detraining.
Article
To examine endogenous hormonal responses to heavy-resistance exercise, ten male strength athletes performed two fatiguing but different types of sessions on separate days. In session A the loads for the leg extensor muscles in the squat-lift exercise were maximal so that the subjects performed 20 sets at 1 repetition maximum (RM) (20 x 1 RM x 100%), whereas during session B the loads were submaximal (70%) but the subjects performed each of the 10 sets until the RM (i.e., 10 repetitions/set or 10 x 10 x 70%). The recovery time between the sets was always 3 min. A decrease of 10.3 +/- 4.7% (P < 0.001) occurred in the squat-lift in 1 RM during session A, whereas session B led to a decrease of 24.6 +/- 18.9% (P < 0.001) in 10 RM. Increases in the concentrations of serum total and free testosterone (P < 0.05 and 0.05, respectively), cortisol (P < 0.001), and growth hormone (GH, P < 0.001) were observed during session B, whereas the corresponding changes during session A were statistically insignificant except for the relatively slight increase (P < 0.01) in serum GH level. The significant (P < 0.001) increase in blood lactate concentration during the two sessions correlated significantly (P < 0.01) with the increase in serum GH concentration. The morning values of serum testosterone and free testosterone were significantly (P < 0.05-0.001) lowered on the 1st and 2nd rest days after the sessions.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Despite full voluntary effort, neuromuscular activation of the quadriceps femoris muscle appears inhibited during slow concentric and eccentric contractions. Our aim was to compare neuromuscular activation during maximal voluntary concentric and eccentric quadriceps contractions, hypothesizing that inhibition of neuromuscular activation diminishes with resistance training. In 15 men, pretraining electromyographic activity of the quadriceps muscles [vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF)] was 17-36% lower during slow and fast (30 and 240 degrees/s) eccentric and slow concentric contractions compared with fast concentric contractions. After 14 wk of heavy resistance training, neuromuscular inhibition was reduced for VL and VM and was completely removed for RF. Concurrently, electromyographic activity increased 21-52, 22-29, and 16-32% for VL, VM, and RF, respectively. In addition, median power frequency decreased for VL and RF. Eccentric quadriceps strength increased 15-17%, whereas slow and fast concentric strength increased 15 and 8%, respectively. Pre- and posttraining median power frequency did not differ between eccentric and concentric contractions. In conclusion, quadriceps motoneuron activation was lower during maximal voluntary eccentric and slow concentric contractions compared with during fast concentric contraction in untrained subjects, and, after heavy resistance training, this inhibition in neuromuscular activation was reduced.
Article
The effect of strength training and endogenously elevated hormone levels (plasma testosterone, growth hormone (GH) and cortisol) was studied in 16 young untrained males, divided into an arm only training group, A, and a leg plus arm training group, LA, in order to increase circulating levels of anabolic hormones. Both groups performed the same one-sided arm training for 9 weeks, twice a week. Group A trained only one arm (AT), the contralateral arm serving as control (AC), whereas group LA additionally trained their legs following the training of the one arm (LAT), with the contralateral arm serving as control (LAC). In spite of the attempt to match the two groups, the initial isometric arm strength was 20-25% lower for group LA compared to group A (significant for the arm to be trained). Isometric strength increased significantly in LAT and LAC by 37% and 10%, respectively, while the 9% and 2% increases in AT and AC, respectively, remained insignificant. Isokinetic strength increased at one out of three velocities tested for the trained arm relative to the untrained arm in both group A and group LA (P<0.05). Functional strength increased significantly by 20% in LAT, 18% in LAC, 19% in AT, and 17% in AC. Hormonal responses were monitored during the first and last training sessions. Resting hormone levels remained unchanged for both groups. However, during the first training session plasma testosterone as well as plasma cortisol increased significantly in group LA but not in group A. Plasma GH rose in all exercise tests, except during the last test in group LA, but was significantly higher in group LA than in group A in the first training session. In conclusion, a larger relative increase in isometric strength was found in the group having the highest hormonal response. However, due to the initial difference in isometric strength caution must be taken with the interpretation of this finding, which may only indicate a possible link between anabolic hormones and muscle strength with training.
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The mechanisms that underlie the affect of acute program variables on muscle growth and strength development for strength/power athletes have been of great interest. This investigation examined the affects of two different resistance exercise protocols on muscle oxygenation, and the anabolic hormonal response to such exercise. Eleven experienced resistance-trained male athletes performed four sets of the squat exercise using either a low-intensity, high-volume (LI; 15 repetitions at 60% one-repetition maximum [1-RM]) or high-intensity, low-volume (HI; 4 repetitions at 90% 1-RM) load. Venous blood samples were obtained before (Pre), immediate (IP), 20- (20P), and 40-min (40P) postexercise. Continuous-wave near-infrared spectroscopy was used to measure oxygen desaturation during exercise. No differences in muscle deoxygenation were seen between LI and HI. However, time-dependent postexercise reoxygenation was significantly different between the two exercise sessions (35.3 +/- 17.4 s vs 24.5 +/- 14.3 s in LI and HI, respectively). Testosterone and growth hormone (GH) concentrations were significantly elevated from Pre at IP, 20P, and 40P in both LI and HI. GH concentrations were higher (P<0.05) for LI than at HI at 20P and 40P. Muscle oxygen recovery kinetics appeared to be influenced by differences in the intensity and volume of exercise, and delayed reoxygenation appears to affect the GH response to exercise.
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1. Skinfold thickness, body circumferences and body density were measured in samples of 308 and ninety-five adult men ranging in age from 18 to 61 years. 2. Using the sample of 308 men, multiple regression equations were calculated to estimate body density using either the quadratic or log form of the sum of skinfolds, in combination with age, waist and forearm circumference. 3. The multiple correlations for the equations exceeded 0.90 with standard errors of approximately +/-0.0073 g/ml. 4. The regression equations were cross validated on the second sample of ninety-five men. The correlations between predicted and laboratory-determined body density exceeded 0.90 with standard errors of approximately 0.0077 g/ml. 5. The regression equations were shown to be valid for adult men varying in age and fatness.
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The present study was conducted to examine (a) whether there is an association between maximal oxygen uptake (Vo(2)max) and reduction in postexercise heart rate (HR) and blood lactate concentrations ([La]) following resistance exercise and (b) how intensity and Volume of resistance exercise affect postexercise Vo(2). Eleven regularly weight-trained males (20.8 +/- 1.3 years; 96.2 +/- 14.4 kg, 182.4 +/- 7.3 cm) underwent 4 sets of squat exercise on 3 separate occasions that differed in both exercise intensity and volume. During each testing session, subjects performed either 15 repetitions.set(-1) at 60% of 1 repetition maximum (1RM) (L), 10 repetitions.set(-1) at 75% of 1RM (M), or 4 repetitions.set(-1) at 90% of 1RM (H). During each exercise, Vo(2) and HR were measured before (PRE), immediately post (IP), and at 10 (10P), 20 (20P) 30 (30P), and 40 (40P) minutes postexercise. The [La] was measured at PRE, IP, 20P, and 40P. Decrease in HR (DeltaHR) was determined by subtracting HR at 10P from that at IP, whereas decrease in [La] (Delta[La]) was computed by subtracting [La] at 20P from that at IP. A significant correlation (p < 0.05) was found between Vo(2)max and DeltaHR in all exercise conditions. A significant correlation (p < 0.05) was also found between Vo(2)max and Delta[La] in L and M but not in H. The Vo(2) was higher (p < 0.05) during M than H at IP and 10P, while no difference was seen between L and M and between L and H. These results indicate that those with greater aerobic capacity tend to have a greater reduction in HR and [La] during recovery from resistance exercise. In addition, an exercise routine performed at low to moderate intensity coupled with a moderate to high exercise volume is most effective in maximizing caloric expenditure following resistance exercise.
Article
The purpose of this study was to examine acute hormonal and neuromuscular responses in men and women to 3 heavy resistance but clearly different exercise protocols: (a) submaximal heavy resistance exercise (SME), (b) maximal heavy resistance exercise (HRE), and (c) maximal explosive resistance exercise (EE). HRE included 5 sets of 10 repetition maximum (10RM) sit-ups, bench press, and bilateral leg extensions (David 210 machine) with a 2-minute recovery between the sets. In SME, the load was 70%, and in EE, the load was 40% from that used in HRE. A significant increase (p < 0.05) in serum growth hormone (GH) was observed after HRE both in men and women, but the increase was greater (p < 0.05) in men than in women. Serum testosterone (T) increased significantly (p < 0.05) only during HRE in men. Since GH and T are anabolic hormones, the acute exercise-induced response during HRE may play an important role in the long-term anabolic adaptation processes related to muscle hypertrophy and maximal strength development.
Article
Six elite women weightlifters were tested to evaluate force-time curve characteristics and intercorrelations of isometric and dynamic muscle actions. Subjects performed isometric and dynamic mid-thigh clean pulls at 30% of maximal isometric peak force and 100 kg from a standardized position on a 61.0 x 121.9 cm AMTI forceplate. Isometric peak force showed strong correlations to the athletes' competitive snatch, clean and jerk, and combined total (r = 0.93, 0.64, and 0.80 respectively). Isometric rate of force development showed moderate to strong relationships to the athletes' competitive snatch, clean and jerk, and combined total (r = 0.79, 0.69, and 0.80 respectively). The results of this study suggest that the ability to perform maximal snatch and clean and jerks shows some structural and functional foundation with the ability to generate high forces rapidly in elite women weightlifters.
Article
Despite the popularity of resistance training (RT), an accurate method for quantifying its metabolic cost has yet to be developed. We applied indirect calorimetry during bench press (BP) and parallel squat (PS) exercises for 5 consecutive minutes at several steady state intensities for 23 (BP) and 20 (PS) previously trained men. Tests were conducted in random order of intensity and separated by 5 minutes. Resultant steady state VO2 data, along with the independent variables load and distance lifted, were used in multiple regression to predict the energy cost of RT at higher loads. The prediction equation for BP was Y' = 0.132 + (0.031)(X1) + (0.01)(X2), R2 = 0.728 and S(xy) = 0.16; PS can be predicted by Y' = -1.424 + (0.022)(X1) + (0.035)(X2), R2 = 0.656 and S(xy) = 0.314; where Y' is VO2 X1 is the load measured in kg and X2 is the distance in cm. Based on a respiratory exchange ratio (RER) of 1.0 and a caloric equivalent of 5.05 kcal x L(-1), VO2 was converted to caloric expenditure (kcal x min(-1)). Using those equations to predict caloric cost, our resultant values were significantly larger than caloric costs of RT reported in previous investigations. Despite a potential limitation of our equations to maintain accuracy during very high-intensity RT, we propose that they currently represent the most accurate method for predicting the caloric cost of bench press and parallel squat.
Article
This study investigated whether muscle hypertrophy-promoting effects are cross-transferred in resistance training with blood flow restriction, which has been shown to evoke strong endocrine activation. Fifteen untrained men were randomly assigned into the occlusive training group (OCC, N = 8) and the normal training group (NOR, N = 7). Both groups performed the same unilateral arm exercise (arm curl) at 50% of one-repetition maximum (1RM) without occlusion (three sets, 10 repetitions). Either the dominant or nondominant arm was randomly chosen to be trained (OCC-T, NOR-T) or to serve as a control (OCC-C, NOR-C). After the arm exercise, OCC performed leg exercise with blood flow restriction (30% of 1RM, three sets, 15-30 repetitions), whereas NOR performed the same leg exercise without occlusion. The training session was performed twice a week for 10 wk. In a separate set of experiments, acute changes in blood hormone concentrations were measured after the same leg exercises with (N = 5) and without (N = 5) occlusion. Cross-sectional area (CSA) and isometric torque of elbow flexor muscles increased significantly in OCC-T, whereas no significant changes were observed in OCC-C, NOR-T, and NOR-C. CSA and isometric torque of thigh muscles increased significantly in OCC, whereas no significant changes were observed in NOR. Noradrenaline concentration showed a significantly larger increase after leg exercise with occlusion than after exercises without occlusion, though growth hormone and testosterone concentrations did not show significant differences between these two types of exercises. The results indicate that low-intensity resistance training increases muscular size and strength when combined with resistance exercise with blood flow restriction for other muscle groups. It was suggested that any circulating factor(s) was involved in this remote effect of exercise on muscular size.
Article
Chronic unilateral motor activity affects the motor output of the contralateral homologous muscle. Such adaptation, or "cross education," indicates an organizational and functional role for the contralateral elements of the central nervous system. In this article, cross education is used as a model to examine this contralateral organization of the human central nervous system. The possibility of whether there are direct changes in the excitability of transcallosal paths and whether, linked to these changes, there are indirect modulations in the excitability of contralateral corticospinal projections is examined. The paper also explores the possibility that there is a spinal component in cross education. The study observed that there is an abundance of evidence to suggest that chronic activation of muscles on one side of the body produces adaptations in the same muscles on the other side of the body in healthy adults as well as in individuals with a variety of pathologies. Data inferred from cross-sectional studies make it likely that interhemispheric and spinal paths both contribute to cross education. Although interhemispheric callosal paths in humans are moderate to dense with the majority of the interhemispheric connections being inhibitory, the connections between the homologous muscles tend to be excitatory, providing a neuroanatomical basis for cross education. The possibility exists that the effects of unilateral practice on interhemispheric inhibition and on the excitability of the contralateral corticospinal projections are linked, and these effects are graded according to the nature of muscle activation. The possibility also exists that cross education is mediated by cross-spinal paths. Cutaneous stimulation appears to exert strong excitatory effects on contralateral motor neurons. In total, an understanding of interhemispheric interactions in the human motor cortex may shed light on the mechanisms of motor learning and the coordination of bilateral movements and improve methods of therapeutic rehabilitation.
Effects of muscle oxygenation during resistance exercise on anabolic hormone response
  • J R Hoffman
  • J Im
  • Rundell
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  • J Kang
  • S Nioka
  • Speiring
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  • R Kime
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Hoffman, JR, Im, J, Rundell, KV, Kang, J, Nioka, S, Speiring, BA, Kime, R, Chance, B. Effects of muscle oxygenation during resistance exercise on anabolic hormone response. Med Sci Sport Exerc, 35, 1929-1934, 2003.
Effects of maximal effort strength training with different loads on dynamic strength, cross sectional area, load-power and load-velocity relationship
  • B M Moss
  • Refses
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  • A Abilgaard
  • K Nicolaysen
  • J Jensen
Moss, BM, Refses, PE, Abilgaard, A, Nicolaysen, K, Jensen, J. Effects of maximal effort strength training with different loads on dynamic strength, cross sectional area, load-power and load-velocity relationship. Eur J Appl Physiol, 75, 193-199, 1997.