Strength Training Period Research Articles

Does A Short Period of Lower Limb Strength Training Improve Performance in Field-Based Tests of Running and Agility in Young Professional Soccer Players?

The present study assessed the effects of specific leg strength training (as part of a broader exercise program) on running speed and agility in young professional soccer players. Twenty-six male players (ages 17 to 19 years) were divided into 3 groups. The reference group (Re) performed individual technical work only, the coordination group (Co) performed a circuit designed to promote agility, coordination, and balance control (together with some technical work) and the Squat group (Sq) underwent 3 series of 3 squat repetitions (at 90% of the individual maximum value) and a sprint, before competition of the agility circuit and some technical work. These specific training programs were performed 5 times a week for 3 weeks. Before the experimental session and at the end of each week, all players were assessed using 4 types of tests, (agility, a shuttle test with changes of direction, and 2 sprints over 10 and 7.32 meters, respectively), with completion time being the only performance parameter recorded. Our results indicate that in the short sprints or shuttle sprint with changes in direction, lower limb strengthening did not improve performance. Performance improved in all 3 groups in the agility test but more so in the reference and coordination groups. It appears that soccer-specific training composed of exercise circuits specifically adapted to the different types of effort actually used in match play can enhance agility and coordination.

Lower muscle strength gains in older men with type 2 diabetes after resistance training

This investigation compared the effects of a twice-weekly whole-body supervised progressive resistance training program in older men with type 2 diabetes with those in healthy older men. Twenty sedentary older men participated in a 16-week progressive resistance training study. They were assigned either to a control group ( n=11) or to a type 2 diabetes group ( n=9). Lower as well as upper body maximal strength (one repetition maximum) and power testing and blood draws to determine basal hormone concentrations (total as well as free testosterone and cortisol) were conducted 4 weeks before training and then at Weeks 0 and 16. The training program consisted of intensities ranging from 50% to 80% of one repetition maximum, 5 to 15 repetitions per set, and three to four sets of each exercise. Baseline maximal muscle strength was not significantly different between groups. After training, significant differences were observed in the magnitude of increments in maximal arm strength and leg strength between the control and type 2 diabetes groups (36.7%±12.9% vs. 24.2%±4.1%, P=.04, and 35.6%±12.2% vs. 17.0%±3.8%, P<.01, respectively), whereas no significant difference was observed between groups in the power output increments of the arm and leg extensor muscles (22.5%±21.3% vs. 23.8%±18.3% and 34.2%±32.0% vs. 33.0%±21.2%, respectively). At baseline, significant differences were observed in the concentrations of total testosterone and cortisol between the control subjects and the patients with type 2 diabetes (20.3±6.0 vs. 10.6±2.9 nmol/l, P<.001, and 546.5±114.7 vs. 343.2±98.4 nmol/l, P<.001, respectively). However, no systematic change was observed during the 16-week strength training period in the basal concentrations of serum total as well as free testosterone and cortisol in both groups. In contrast, statistically significant correlations were observed in a combined group of healthy older men and older men with type 2 diabetes (H+D group) between the mean levels of individual serum total testosterone and cortisol (averaged for the entire training period) and the individual changes in maximal leg strength and arm strength ( r=0.85–0.51 and 0.63–0.70, respectively, P<.05). In summary, it would appear that older subjects with type 2 diabetes are equally trainable for muscle power output but not for maximal strength as their healthy counterparts.

Changes in Aerobic and Anaerobic Power Indices in Elite Handball Players Following a 4-Week General Fitness Mesocycle

Changes in Aerobic and Anaerobic Power Indices in Elite Handball Players Following a 4-Week General Fitness Mesocycle The aim of this study was to evaluate the effects of a 4-week training programme during the first phase of the preparation period on selected indices of somatic structure as well as aerobic and anaerobic power in elite handball players. Nine handball players from a first league team took part in the study; their average age was 25.5±3.7 years, body mass 86.5±7.6 kg (I session) and 87.9±7.3 kg (II session) (p&lt;0.01), lean body mass - 74.4±6.6 kg (I) and 76.2± 6.2 kg (II) (p&lt;0.01), body fat mass 12.1±3.1 kg (I) and 11.7±3.1 kg (II) respectively. Two evaluations were conducted - the first at the end of the season, the second at the initial phase of the preparation period. The second phase was preceded by a 4- week period of general endurance and strength training. Aerobic fitness was assessed indirectly, taking into account the results of the PWC170 test. The absolute and relative values of the PWC170 index increased significantly from 236.6 W to 269 W (p&lt;0.01) and from 2.73 W/kg to 3.06 W/kg (p&lt;0.01). The values of maximum oxygen uptake - VO2max were significantly improved from 3.65 l/min to 3.98 l/min (p&lt;0.01) and from 42.3 ml/kg/min to 45.4 ml/kg/min (p&lt;0.05). Anaerobic fitness was assessed using the 30-second Wingate test. A statistically significant improvement of the basic indices of aerobic fitness following the 4-week training programme proved its high effectiveness. Maintaining the level of the basic indices of anaerobic power despite the absence of specific training loads, seems to corroborate the strong effect of genetic factors on the level of anaerobic fitness and the effectiveness of strength training programs.

High eccentric strength training reduces heart rate variability in healthy older men

Background:Evaluation of non-pharmacological therapies that improve autonomic control of the heart rate in older subjects has a clinical significance, because reduced heart rate variability (HRV) can be associated with higher...

Effects Of Strength TVaining By Electrostimulation On Skeletal Muscle Oxidative Metabolism

Strength training is frequently associated with endurance exercise during training and rehabilitation. The effects of strength training (particularly when obtained by electrostimulation) per se on skeletal muscle oxidative metabolism are not well known. PURPOSE: To evaluate the effects of strength training by electrostimulation on variables of functional evaluation of oxidative metabolism specifically aimed at skeletal muscle. METHODS: Measurements were conducted on 7 young untrained subjects, during incremental cycloergometric exercises up to voluntary exhaustion and 6-min constant-load exercises below and above the gas exchange threshold (GET). Measurements were carried out before (B) and after (A) a strength training period (25 sessions of neuromuscular electrical stimulation of both quadriceps, over 8 weeks), which determined a 24% increase in force during maximal voluntary contraction. Breath-by-breath pulmonary O2 uptake (VO2) and vastus lateralis oxygenation indices by continuous-wave near-infrared spectroscopy (NIRS) were determined. Skeletal muscle O2 extraction was estimated by NIRS on the basis of changes in concentration of deoxygenated hemoglobin + myoglobin (Delta[deoxy(Hb+Mb)]), expressed as a percentage of values obtained during transient limb ischemia. RESULTS: VO2 peak and Delta[deoxy(Hb+Mb)] peak were, respectively, 44.5 ± 3.1 (x ± SE) ml/kg/min in B vs. 47.8 ± 2.2 in A; and 84.2 ± 6.0 % in B vs. 85.4 ± 6.3 in A. GET occurred at 66.6 ± 2.8 % of VO2 peak in B, vs. 67.6 ± 3.5 in A. The time-constant of VO2 kinetics during the transition to constant-load exercise below GET was 34.7 ±6.8 s in B vs. 32.3 ± 4.3 in A. During constant-load exercise above GET slow components of VO2 and Delta[deoxy(Hb+Mb)] kinetics were observed. For VO2, the slow component amplitude, expressed as a percentage of the total response, was 17.8 ± 3.3 % in B, vs. 11.7 ± 2.5 in A. With exception of force, all differences, in A vs. B, were not statistically significant. CONCLUSIONS: In young subjects a strength training program by electrostimulation of the vastus lateralis, capable of significantly increasing muscle force, did not significantly affect VO2 peak and other variables of functional evaluation specifically aimed at skeletal muscle oxidative metabolism.

High Strength Training Reduces The Heart Rate Variability In Older Healthy Men

Evaluate non-pharmacological therapies that improve the autonomic control of heart rate of older subjects has a clinical significance, since reduced heart rate variability (HRV) can be associated with higher cardiovascular morbidity and mortality rates. PURPOSE: To investigate if the strength training improves the cardiac autonomic control in healthy older men. METHODS: 9 older healthy men (62 ±2.0 years) took part of the present study. Electrocardiogram was continuously recorded for 15 min at rest, in the supine and seated position, before and after the strength training (ST) period. The effect of ST on arterial blood pressure was also assessed. To estimate the strength gains, isokinetic eccentric (ECC) knee extension and flexion peak torque (PT) of the dominant leg were measured at 60°/sec through a range from 90° to 30° knee flexion, by an isokinetic dynamometer. The ST program consisted in 2–4 sets of 8–12 repetitions of the bilateral knee eccentric flexion and extension, which was performed on the same dynamometer. Subjects trained 2d.wk-1 for 12 wk with resistance equaling approximately 70–80% of PT. Resting HR and RR intervals were analyzed by time (RMSSD index) and frequency domain methods. The power spectral components are reported in normalized units (nu) at low (LF) and high (HF) frequency, and as the LF/HF ratio. The effect of strength training was assessed by two-way ANOVA for repeated measures followed, when appropriate, by post hoc analysis. The level of significance was set at α=5%. RESULTS: Systolic blood pressure decreased (123.8 ± 8.3 to 117.7 ± 10.2 mmHg, P<0.05) and PT increased (extension: 210.0 ± 38.5 to 252.7 ± 60.9 N.m; flexion 117.6 ± 25.1 to 132.9 ± 27.3 N.m, P<0.05) after the ST. The frequency domain indices showed a significant training effect (P<0.05), since LF and LF/HF increased (supine= 57 ±14 to 68 ±14, 1.56 ±.85 to 2.35 ±1.48; seated= 65 ±15 to 74 ±8.0, 2.48 ±1.09 to 3.19 ±1.31, respectively), and HF decreased (supine= 43 ±14 to 32 ±14; seated= 35 ±15 to 26 ±8). CONCLUSION: The results of the present investigation suggest that high strength eccentric training, performed by older healthy men, increase the peak torque and reduce the blood systolic pressure. However, it causes an autonomic imbalance into sympathetic predominance, which mechanism is not clear.

Effects of strength and endurance training on antioxidant enzyme gene expression and activity in middle‐aged men

This study was aimed at investigating the effects of a 21-week period of progressive strength or endurance training on peripheral blood mononuclear cells (PBMC) antioxidant enzyme gene expression and activity in healthy middle-aged untrained men. Strength (n=11) and endurance (n=12) training were performed twice a week, including resistance exercises to activate all the main muscle groups or cycle-ergometer pedaling, respectively. mRNA levels of catalase, glutathione peroxidase (GPx), mitochondrial superoxide dismutase (MnSOD) and cytosolic superoxide dismutase (CuZnSOD) were increased after 21 weeks of strength training, while endurance training induced significant changes only in MnSOD and GPx mRNA levels. CuZnSOD protein content was significantly increased only in strength-trained subjects. The program of strength or endurance exercise training had no significant effects on the activity of any of the antioxidant enzymes. In conclusion, in a middle-aged population, 21 weeks of strength or endurance training was a sufficient stimulus to up-regulate mRNA levels of PBMC antioxidant enzymes, the strength training being a more optimal stimulus. However, the discrepancies between enzyme protein and mRNA levels suggest that the present systematic strength or endurance training period had no beneficial effects on enzymatic antioxidant defense mechanisms in previously untrained middle-aged men.

Postexercise Myostatin and Activin IIb mRNA Levels

Muscle hypertrophy is likely to result from the cumulative effects of repeated bouts of resistance exercise (RE) on postexercise molecular responses. Therefore, we determined muscle growth- and regeneration-related mRNA expression in response to a single RE bout both before and after a strength-training (ST) period. By means of this novel longitudinal setting, we examined whether postexercise gene expression at the transcriptional level is different in the trained and untrained state. Eleven untrained healthy older men and 11 controls (age 62.3 +/- 6.3 yr) volunteered as subjects. Muscle biopsies from the vastus lateralis muscle were taken at rest and 1 and 48 h after five sets of 10-repetition leg press RE both before and after 21 wk of supervised ST. Myostatin and myogenin mRNA expression, determined by real-time RT-PCR, increased (P < 0.05) after ST. Conversely, the single RE bout decreased myostatin mRNA after ST, with the decrease showing a negative correlation (r = -0.65, P < 0.05) with the long-term increase in myostatin during ST. Furthermore, RE before ST increased myogenin mRNA (P < 0.05) and tended to increase after ST (P = 0.08). Myostatin receptor activin IIb mRNA levels were decreased at 1 h after RE in the pre-ST condition (P = 0.05) and also tended to decrease in the post-ST condition (P = 0.07). RE-induced downregulation in myostatin mRNA correlated with the ST-induced increase in total body muscle mass (r = -0.82, P = 0.002). A single bout of RE in older men can downregulate the expression of myostatin receptor activin IIb mRNA. ST influences the response of myostatin to RE, as short-term RE-induced downregulation of myostatin was observed only after ST. The results also indicate that RE-induced alterations in myostatin mRNA expression may have a role in ST-induced muscle hypertrophy.

Suppression of testosterone does not blunt mRNA expression of myoD, myogenin, IGF, myostatin or androgen receptor post strength training in humans

We hypothesized that suppression of endogenous testosterone blunts mRNA expression post strength training (ST). Twenty-two young men were randomized for treatment with the GnRH analogue goserelin (3.6 mg every 4 weeks) or placebo for a period of 12 weeks. The ST period of 8 weeks started at week 4. Strength test, blood sampling, muscle biopsies, and whole-body dual-energy X-ray absorptiometry (DXA) scan were performed at weeks 4 and 12. Muscle biopsies were taken during the final ST session (pre, post 4 h, and post 24 h). Resting serum testosterone decreased significantly (P < 0.01) in the goserelin group from 22.6 +/- 1.6 (mean +/- s.e.m.) to 2.0 +/- 0.1 nmol l(-1) (week 4), whereas it remained unchanged in the placebo group. An acute increase of serum testosterone was observed during the final ST session in the placebo group (P < 0.05), whereas a decreased response was observed in the goserelin group (P < 0.05). mRNA expression of IGF-IE(bc) and myogenin increased, while expression of myostatin decreased (P < 0.01); however, no differences were observed between the groups. Muscle strength and muscle mass showed a tendency to increase more in the placebo group than in the goserelin group (P = 0.05). In conclusion, despite blocked acute responses of testosterone and 10- to 20-fold lower resting levels in the goserelin group, ST resulted in a similar mRNA expression of myoD, myogenin, IGF-IE(abc), myostatin and androgen receptor as observed in the placebo group. Therefore, in the present study, the molecular events were the same, despite divergent muscle hypertrophy and strength gains.

Effect of Time‐of‐Day‐Specific Strength Training on Serum Hormone Concentrations and Isometric Strength in Men

A time‐of‐day influence on the neuromuscular response to strength training has been previously reported. However, no scientific study has examined the influence of the time of day when strength training is performed on hormonal adaptations. Therefore, the primary purpose of this study was to examine the effects of time‐of‐day‐specific strength training on resting serum concentrations and diurnal patterns of testosterone (T) and cortisol (CORT) as well as maximum isometric strength of knee extensors. Thirty eight diurnally active healthy, previously untrained men (age 20–45 yrs) underwent a ten‐week preparatory strength training period when sessions were conducted between 17:00–19:00 h. Thereafter, these subjects were randomized into either a morning (n=20, training times 07:00–09:00 h) or afternoon (n=18, 7:00–19:00 h) training group for another ten‐week period of time‐of‐day‐specific training (TST). Isometric unilateral knee extension peak torque (MVC) was measured at 07:00, 12:00, 17:00, and 20:30 h over two consecutive days (Day 1 & Day 2) before and after TST. Blood samples were obtained before each clock‐time measurement to assess resting serum T and CORT concentrations. A matched control group (n=11) did not train but participated in the tests. Serum T and CORT concentrations significantly declined from 07:00 to 20:30 h on all test days (Time effect, p<.001). Serum CORT at 07:00 h was significantly higher on Day 1 than Day 2 in the control and afternoon group, both in Pre and Post conditions (Day×Time interaction, p<.01). In the morning group, a similar day‐to‐day difference was present in the Pre but not Post conditions (Time×Group interaction, p<.05). MVC significantly increased after TST in both the morning and afternoon groups (Pre to Post effect, p<.001). In both groups, a typical diurnal variation in MVC (Time effect, p<.001) was found, especially on Day 2 in the Pre condition, and this feature persisted from Pre to Post in the afternoon group. In the morning group, however, diurnal variation was reduced after TST on both Day 1 and Day 2 (Pre to Post×Day×Time×Group interaction, p<.05). In conclusion, 10 weeks of morning time‐of‐day‐specific strength training resulted in reduced morning resting CORT concentrations, presumably as a result of decreased masking effects of anticipatory psychological stress prior to the morning testing. The typical diurnal pattern of maximum isometric strength was blunted by the TST period in the morning but not the afternoon group. However, the TST period had no significant effect on the resting total T concentration and its diurnal pattern and on the absolute increase in maximum strength.

Lack of human muscle architectural adaptation after short‐term strength training

The mechanisms governing the increases in force production in response to short periods of strength training have yet to be fully elucidated. We examined whether muscle architectural adaptation was a contributing factor. Ultrasound imaging techniques were used to measure quadriceps muscle architecture at 17 sites in vivo in trained and untrained legs of men and women after 2.5 and 5 weeks of unilateral knee extension training, as well as in a nontraining control group. Despite increases in knee extensor strength of the trained and untrained (women only) legs, there were no changes in muscle thickness, fascicle angle, or fascicle length in any of the muscles tested. The moderate correlation between vastus lateralis thickness (middle site) and eccentric (r = 0.55; P < 0.05) and concentric (r = 0.46; P < 0.1) torque after, but not before, training is suggestive of neural rather than architectural adaptations predominating in the early phase of training.

The metabolic effects of long term exercise in Type 2 Diabetes patients

The effectiveness of physical exercise in the management of diabetes mellitus type 2 is well established. The purpose of this investigation was to evaluate the effect of long term exercise on glycemic and metabolic control measured after eight months in contrast to patients who had ceased their training after four months. After an effective 4 months' strength training or endurance training period, ten patients (5 male and 5 female, mean age +/- SE:57.1 +/- 1.6 yr) were randomised to a further 4 months of combined endurance and strength training, while a control group of 10 patients (5 male and 5 female, mean age +/- SE:56.9 +/- 1.6 yr) ceased training. Long term glycemic control improved and HbA1C values fell from 6.9 +/- 0.4 to 6.2 +/- 0.2 in active patients and increased from 7.5 +/- 0.4 to 8.7 +/- 0.6 in control patients (p = 0.002). Baseline levels of total cholesterol significantly decreased in training group (205.5 mg/dl +/- 14.1 to 177.5 +/- 13.3) and increased in controls (185.9 +/- 14.1 to 220.2 +/- 15.8) [p = 004]. In addition, significant decreases in LDL-cholesterol and triglyceride levels (both p < 05) were observed in the training group compared to controls. This study showed that in addition to a 4 month training period, continuation of training proved highly beneficial with further reductions in fasting blood glucose, HbA1C, total cholesterol, LDL-cholesterol, triglyceride, and an elevation in HDL-cholesterol concentrations in diabetes mellitus type 2 patients, thus resulting in a reduced atherogenic lipid profile. In contrast, patients who ceased training after 4 months developed an atherogenic lipid profile and a worsened glycemic control. The results of this study indicate that long term exercise plays an important role in the treatment of diabetes mellitus type 2 and may protect against the development of cardiovascular diseases.

Suppression of endogenous testosterone production attenuates the response to strength training: a randomized, placebo-controlled, and blinded intervention study

We hypothesized that suppression of endogenous testosterone would inhibit the adaptations to strength training in otherwise healthy men. Twenty-two young men with minor experience with strength training participated in this randomized, placebo-controlled, double-blinded intervention study. The subjects were randomized to treatment with the GnRH analog goserelin (3.6 mg) or placebo (saline) subcutaneously every 4 wk for 12 wk. The strength training period of 8 wk, starting at week 4, included exercises for all major muscles [3-4 sets per exercise x 6-10 repetitions with corresponding 6- to 10-repetition maximum (RM) loads, 3/wk]. A strength test, blood sampling, and whole body DEXA scan were performed at weeks 4 and 12. Endogenous testosterone decreased significantly (P < 0.01) in the goserelin group from 22.6 +/- 5.5 (mean +/- SD) nmol/l to 2.0 +/- 0.5 (week 4) and 1.1 +/- 0.6 nmol/l (week 12), whereas it remained constant in the placebo group. The goserelin group showed no changes in isometric knee extension strength after training, whereas the placebo group increased from 240.2 +/- 41.3 to 264.1 +/- 35.3 Nm (P < 0.05 within and P = 0.05 between groups). Lean mass of the legs increased 0.37 +/- 0.13 and 0.57 +/- 0.30 kg in the goserelin and placebo groups, respectively (P < 0.05 within and P = 0.05 between groups). Body fat mass increased 1.4 +/- 1.0 kg and decreased 0.6 +/- 1.2 kg in the goserelin and placebo groups, respectively (P < 0.05 within and between groups). We conclude that endogenous testosterone is of paramount importance to the adaptation to strength training.

The Significance of Endogenous Testosterone on the Adaptation to Strength Training

Endogenous testosterone (ET) interacts with skeletal muscle and is a component of an integrated endocrine system that seems to mediate the adaptive changes in muscles as a result of strength training (ST). In addition, the myogenic regulating factors (MRFs) including myoD and myogenin seem to play an essential role in the ST induced muscle hypertrophy. The interaction between ST, levels of ET, myoD and myogenin, muscle hypertrophy and increased strength has not been examined. PURPOSE: Suppression of ET will inhibit the adaptation to ST with a concomitant decrease in the mRNA expression of myoD and myogenin, leading to a less pronounced increase in lean mass and muscle strength. METHODS: Twenty-two moderately trained young men with no experience of ST volunteered to participate in this randomized, placebo-controlled, intervention study. The subjects were divided in two groups (zoladex (Z) n = 1 2 and placebo (P) n = 1 0). ET levels were suppressed using injections of GnRH-analogue (Zoladex, AstraZeneca). Zoladex (3.6 mg) or placebo (saline) was administered sub cutaneous ly every 4 wk for a period of 12 wk. The ST period started 3 wk after the first injection and the subjects were assigned to a full body ST program emphasizing the legs for 8 wk. Subjects trained 6–10 reps with corresponding 6–10 RM loads x 3 – 4 sets per exercise, 3/wk. Before and after the ST period strength test (Kin-Com 500H, USA) and whole body DEXA scan (Hologic 4500) were performed. Biopsies were taken in the right vastus lateralis at 4 time points to measure the mRNA expression of myoD and myogenin. Before (biopsy nr. 1.) and after (nr. 2.) the ST period and in relation to the last ST session (pre (nr. 2.), 4 h post (nr. 3.) and 24 h post (nr. 4.)). MyoD and myogenin mRNA expression were normalized to GAPDH. RESULTS: Absolute isometric strength increased significantly after 8 wk of ST in P from 240.2 ± 41.3 (SD) Nm to 264.1 ± 35.3 Nm (p<0.05) while Z showed no changes 224.8 ± 44.4 to 230.0 ± 39.8 Nm (p = 0.05 between groups). Lean mass for the legs increased 0.38 ± 0.1 kg in Z and 0.57 ± 0.3 kg in P (p<0.05 within and p = 0.05 between groups). MyoD expression showed no changes between different time points, whereas myogenin expression was nearly 4 fold higher when comparing biopsy nr. 3. with biopsy nr. 2. (p<0.05). In addition, biopsy nr. 3. and 4. was significantly higher than biopsy nr. 1. and 2. (p<0.05). There were no differences between the myogenin expression in the two groups. CONCLUSIONS: This study showed that ST with suppression of ET production does not inhibit local cellular mRNA expression of myogenin but leads to a less pronounced increase in lean mass and no increase in muscle strength.

Strength Training Leading to Failure Induces Insulin-like Growth Factor-I Reduction and IGFBP-3 Elevation

Dramatic changes in volume and intensity of the training stimulus can overstress the nervous and endocrine systems leading to an elevated catabolic and/or lowered anabolic state. It can be hypothesized that a training approach where each repetition was not performed to failure would result in minor changes in resting anabolic/ catabolic hormones. PURPOSE: To examine the efficacy of 11 weeks of resistance training to failure vs. non-failure, followed by an identical 5- week peaking period of maximal strength and power training for both groups as well as to examine the underlying physiological changes in basal circulating anabolic/catabolic hormones. METHODS: Forty-two physic ally-active men were matched and then randomly assigned to either a training to failure (RF; n=14), non-failure (NRF; n=15) or control groups (C; n=13). Muscular and power testing and blood draws to determine basal hormonal concentrations were conducted before the initiation of training (T0), after 6 wk of training (T1), after 11 wk of training (T2), and after 16 wk of training (T3). Subjects undertook a 16-wk (mesocycle) periodized resistance training program divided into three microcycles of 5–6 wk. One group performed high-fatigue strength training exercise to failure (3sets of 10RM and 3sets of 6RM), whereas the other performed the same volume and intensity but did not complete sets to failure (6 sets of 5 reps at 10RM and 6 sets of 3 reps at 6RM), from T0 to T1 and T1 to T2, respectively. During the peaking phase (from T2 to T3), both groups trained at 75%–80% of 1RM (∼5RM), 3 sets of 2–4 repetitions and performed a ballistic training program (i.e. Vertical jumps, sprint runs and various throwing exercises). RESULTS: Both RF and NRF resulted in similar gains in 1RM bench press (23% and 23% and) and half squat (22% and 23%), and muscle power output of the arm (27% and 28%) and leg extensor muscles (26% and 29%). The peaking phase (T2 to T3) followed after NRF resulted in larger gains in muscle power output of the lower extremities. Strength training leading to RF resulted in reductions in resting concentrations of IGF-1 and elevations in IGFBP-3, whereas NRF resulted in reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration. CONCLUSIONS This investigation demonstrated a potential beneficial stimulus of NRF for improving strength and power, especially during the subsequent peaking training period. Elevation in IGFBP-3 following resistance training may have been compensatory to accommodate the reduction in IGF-1 in order to preserve IGF availability.

Resistance Exercise-Induced Myostatin mRNA Expression Before and After a 6-month Strength Training Period

Myostatin (MSTN) inhibits skeletal muscle growth and it may also inhibit training-induced muscle growth. MSTN acts by binding to the activin IIb receptor (ActIIb) but its binding can be inhibited by follistatin-related gene (FLRG) protein. Decreased MSTN mRNA expression has been shown in untrained subjects 24h after a single resistance exercise (RE). This molecular response may be important in strength training (ST) mediated hypertrophy together with possible changes in ActIIb and FLRG expression. PURPOSE: To determine MSTN, ActIIb and FLRG responses at mRNA level to a single RE before and after six months of ST. METHODS: Nine (61.0±5.5 yrs) previously untrained healthy men participated in the study. RE was performed one wk before and one wk after ST. The RE included 5 sets of 10RM bilateral leg presses. Muscle biopsies were taken from the vastus lateralis 0.5h before (pre), and 1h (post 1h) as well as 48h (post 48h) after the RE. MSTN, ActIIb and FLRG mRNA expression were determined by Taqman probe-based realtime RT-PCR. RESULTS: The basal (pre) MSTN mRNA levels were significantly increased during the ST (p<0.05) (Fig 1). After ST the MSTN post 48h levels were significantly lower compared to the corresponding pre RE levels (p<0.01). The ActIIb mRNA levels decreased before and after ST due to RE (post 1h p<0.05; post 48h p<0.10). No changes were observed in FLRG mRNA.Fig 1: Resistance exercise-induced myostatin mRNA expression before and after ST.CONCLUSION: The present study showed that ST increased basal MSTN levels, which has been shown previously in some but not all studies. The novel finding was that both MSTN and its receptor ActIIb levels decreased due to RE. However, the decrease in MSTN was observed only in post-training RE. Both of these decreases probably decrease the catabolic action of MSTN. The present study indicates that resistance exercise decreases MSTN and ActIIb expression, at least after training. Both of these anabolic responses may be important in the skeletal muscle hypertrophy process, and they should be examined in the future. Supported by the Finnish Ministry of Education.

Acute heavy‐resistance exercise–induced pain and neuromuscular fatigue in elderly women with fibromyalgia and in healthy controls: Effects of strength training

To examine heavy-resistance exercise-induced acute neuromuscular fatigue, blood lactate concentration, and muscle pain in elderly women with fibromyalgia (FM) and in healthy controls before and after a period of strength training. Thirteen elderly women with FM (mean+/-SD age 60+/-2 years) and 10 healthy women (mean+/-SD age 64+/-3 years) performed a heavy-resistance fatiguing protocol (5 sets of leg presses with 10 repetitions maximum) before and after a 21-week strength training period. Maximal isometric force and electromyography (EMG) activity of leg extensors and blood lactate concentration were measured during the loading. Pain was assessed by visual analog scale. The strength training led to large increases in maximal force and EMG activity of the muscles and contributed to the improvement in loading performance (average load/set) at week 21. The fatiguing loading sessions typically applied in strength training before and after the experimental period caused remarkable and comparable acute decreases in maximal force and increases in blood lactate concentration in both groups. Acute exercise-induced muscle pain increased similarly in both groups, and the pain level in women with FM was lowered after the 21-week training period. The increased strength in women with FM improved high-load performance and also seemed to attenuate perceived pain. Acute exercise-induced neuromuscular changes and the time course of muscle pain in women with FM were comparable with findings in healthy controls, which suggests a typical fatiguing process and a similar trainability of the muscles in elderly women with FM.

Differential effects of strength training leading to failure versus not to failure on hormonal responses, strength, and muscle power gains

The purpose of this study was to examine the efficacy of 11 wk of resistance training to failure vs. nonfailure, followed by an identical 5-wk peaking period of maximal strength and power training for both groups as well as to examine the underlying physiological changes in basal circulating anabolic and catabolic hormones. Forty-two physically active men were matched and then randomly assigned to either a training to failure (RF; n = 14), nonfailure (NRF; n = 15), or control groups (C; n = 13). Muscular and power testing and blood draws to determine basal hormonal concentrations were conducted before the initiation of training (T0), after 6 wk of training (T1), after 11 wk of training (T2), and after 16 wk of training (T3). Both RF and NRF resulted in similar gains in 1-repetition maximum bench press (23 and 23%) and parallel squat (22 and 23%), muscle power output of the arm (27 and 28%) and leg extensor muscles (26 and 29%), and maximal number of repetitions performed during parallel squat (66 and 69%). RF group experienced larger gains in the maximal number of repetitions performed during the bench press. The peaking phase (T2 to T3) after NRF resulted in larger gains in muscle power output of the lower extremities, whereas after RF it resulted in larger gains in the maximal number of repetitions performed during the bench press. Strength training leading to RF resulted in reductions in resting concentrations of IGF-1 and elevations in IGFBP-3, whereas NRF resulted in reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration. This investigation demonstrated a potential beneficial stimulus of NRF for improving strength and power, especially during the subsequent peaking training period, whereas performing sets to failure resulted in greater gains in local muscular endurance. Elevation in IGFBP-3 after resistance training may have been compensatory to accommodate the reduction in IGF-1 to preserve IGF availability.

SHORT VS.LONG REST PERIOD BETWEEN THE SETS IN HYPERTROPHIC RESISTANCE TRAINING

Acute and long-term hormonal and neuromuscular adaptations to hypertrophic strength training were studied in 13 recreationally strength-trained men. The experimental design comprised a 6-month hypertrophic strength-training period including 2 separate 3-month training periods with the crossover design, a training protocol of short rest (SR, 2 minutes) as compared with long rest (LR, 5 minutes) between the sets. Basal hormonal concentrations of serum total testosterone (T), free testosterone (FT), and cortisol (C), maximal isometric strength of the leg extensors, right leg 1 repetition maximum (1RM), dietary analysis, and muscle cross-sectional area (CSA) of the quadriceps femoris by magnetic resonance imaging (MRI) were measured at months 0, 3, and 6. The 2 hypertrophic training protocols used in training for the leg extensors (leg presses and squats with 10RM sets) were also examined in the laboratory conditions at months 0, 3, and 6. The exercise protocols were similar with regard to the total volume of work (loads 3 sets 3 reps), but differed with regard to the intensity and the length of rest between the sets (higher intensity and longer rest of 5 minutes vs. somewhat lower intensity but shorter rest of 2 minutes). Before and immediately after the protocols, maximal isometric force and electro-myographic (EMG) activity of the leg extensors were measured and blood samples were drawn for determination of serum T, FT, C, and growth hormone (GH) concentrations and blood lactate. Both protocols before the experimental training period (month 0) led to large acute increases (p < 0.05–0.001) in serum T, FT, C < and GH concentrations, as well as to large acute decreases (p < 0.05–0.001) in maximal isometric force and EMG activity. However, no significant differences were observed between the protocols. Significant increases of 7% in maximal isometric force, 16% in the right leg 1RM, and 4% in the muscle CSA of the quadriceps femoris were observed during the 6-month strength-training period. However, both 3-month training periods performed with either the longer or the shorter rest periods between the sets resulted in similar gains in muscle mass and strength. No statistically significant changes were observed in basal hormone concentrations or in the profiles of acute hormonal responses during the entire 6-month experimental training period. The present study indicated that, within typical hypertrophic strength-training protocols used in the present study, the length of the recovery times between the sets (2 vs. 5 minutes) did not have an influence on the magnitude of acute hormonal and neuromuscular responses or long-term training adaptations in muscle strength and mass in previously strength-trained men.

Short vs. Long Rest Period Between the Sets in Hypertrophic Resistance Training: Influence on Muscle Strength, Size, and Hormonal Adaptations in Trained Men

Acute and long-term hormonal and neuromuscular adaptations to hypertrophic strength training were studied in 13 recreationally strength-trained men. The experimental design comprised a 6-month hypertrophic strength-training period including 2 separate 3-month training periods with the crossover design, a training protocol of short rest (SR, 2 minutes) as compared with long rest (LR, 5 minutes) between the sets. Basal hormonal concentrations of serum total testosterone (T), free testosterone (FT), and cortisol (C), maximal isometric strength of the leg extensors, right leg 1 repetition maximum (1RM), dietary analysis, and muscle cross-sectional area (CSA) of the quadriceps femoris by magnetic resonance imaging (MRI) were measured at months 0, 3, and 6. The 2 hypertrophic training protocols used in training for the leg extensors (leg presses and squats with 10RM sets) were also examined in the laboratory conditions at months 0, 3, and 6. The exercise protocols were similar with regard to the total volume of work (loads x sets x reps), but differed with regard to the intensity and the length of rest between the sets (higher intensity and longer rest of 5 minutes vs. somewhat lower intensity but shorter rest of 2 minutes). Before and immediately after the protocols, maximal isometric force and electromyographic (EMG) activity of the leg extensors were measured and blood samples were drawn for determination of serum T, FT, C, and growth hormone (GH) concentrations and blood lactate. Both protocols before the experimental training period (month 0) led to large acute increases (p < 0.05-0.001) in serum T, FT, C , and GH concentrations, as well as to large acute decreases (p < 0.05-0.001) in maximal isometric force and EMG activity. However, no significant differences were observed between the protocols. Significant increases of 7% in maximal isometric force, 16% in the right leg 1RM, and 4% in the muscle CSA of the quadriceps femoris were observed during the 6-month strength-training period. However, both 3-month training periods performed with either the longer or the shorter rest periods between the sets resulted in similar gains in muscle mass and strength. No statistically significant changes were observed in basal hormone concentrations or in the profiles of acute hormonal responses during the entire 6-month experimental training period. The present study indicated that, within typical hypertrophic strength-training protocols used in the present study, the length of the recovery times between the sets (2 vs. 5 minutes) did not have an influence on the magnitude of acute hormonal and neuromuscular responses or long-term training adaptations in muscle strength and mass in previously strength-trained men.