Physiological elevation of endogenous hormones results in superior strength training adaptation
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY   Bent R. Rønnestad, Håvard Nygaard and Truls Raastad

The purpose of this study was to determine the influence of transiently elevated endogenous hormone concentrations during exercise on strength training adaptations. Nine subjects performed four unilateral strength training session per week on the elbow flexors for 11 weeks. During two of the weekly sessions, leg exercises were performed to acutely increase the systemic anabolic hormone concentration immediately before the exercises for one of the elbow flexors (L + A). On the two other weekly training sessions, the contralateral elbow flexors were trained without prior leg exercises (A). By randomizing one arm of the subjects to serve as a control and the other as experimental, both conditions have the same nutritional and genetic environment. Serum testosterone and growth hormone was significantly increased during the L − A training session, while no hormonal changes occurred in the A session. Both A and L + A increased 1RM in biceps curl, peak power in elbow flexors at 30 and 60% of 1RM, and muscle volume of the elbow flexors (p < 0.05). However, only L + A achieved increase in CSA at the part of the arm flexors with largest cross sectional area (p < 0.001), while no changes occurred in A. L + A had superior relative improvement in 1RM biceps curl and favorable muscle adaptations in elbow flexors compared to A (p < 0.05). In conclusion, performing leg exercises prior to arm exercises, and thereby increasing the levels of serum testosterone and growth hormone, induced superior strength training adaptations compared to arm training without acute elevation of hormones.

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An examination of the time course of training-induced skeletal muscle hypertrophy
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY
Jason M. DeFreitas, Travis W. Beck, Matt S. Stock, Michael A. Dillon and Paul R. Kasishke

Skeletal muscle hypertrophy is typically considered to be a slow process. However, this is partly because the time course for hypertrophy has not been thoroughly examined. The purpose of this study was to use weekly testing to determine a precise time course of skeletal muscle hypertrophy during a resistance training program. Twenty-five healthy, sedentary men performed 8 weeks of high-intensity resistance training. Whole muscle cross-sectional area (CSA) of the dominant thigh was assessed using a peripheral quantitative computed tomography scanner during each week of training (W1–W8). Isometric maximum voluntary contractions (MVC) were also measured each week. After only two training sessions (W1), the mean thigh muscle CSA increased by 5.0 cm2 (3.46%; p

significant skeletal muscle hypertrophy likely occurred around weeks 3–4. Overall, from the pre-testing to W8, there was an increase of 13.9 cm2 (9.60%). These findings suggested that training-induced skeletal muscle hypertrophy may occur early in a training program.

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Strength and neuromuscular adaptation following one, four, and eight sets of high intensity resistance exercise in trained males
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY   P. W. M. Marshall, M. McEwen and D. W. Robbins

The optimal volume of resistance exercise to prescribe for trained individuals is unclear. The purpose of this study was to randomly assign resistance trained individuals to 6-weeks of squat exercise, prescribed at 80% of a 1 repetition-maximum (1-RM), using either one, four, or eight sets of repetitions to failure performed twice per week. Participants then performed the same peaking program for 4-weeks. Squat 1-RM, quadriceps muscle activation, and contractile rate of force development (RFD) were measured before, during, and after the training program. 32 resistance-trained male participants completed the 10-week program. Squat 1-RM was significantly increased for all groups after 6 and 10-weeks of training (P

(P < 0.05). Peak muscle activation did not change during the study. Early (30, 50 ms) and peak RFD was significantly decreased for all groups after 6 and 10-weeks of training (P < 0.05). Peak isometric force output did not change for any group. The results of this study support resistance exercise prescription in excess of 4-sets (i.e. 8-sets) for faster and greater strength gains as compared to 1-set training. Common neuromuscular changes are attributed to high intensity squats (80% 1-RM) combined with a repetition to failure prescription. This prescription may not be useful for sports application owing to decreased early and peak RFD. Individual responsiveness to 1-set of training should be evaluated in the first 3-weeks of training.

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Ca parait évident mais ça n’a pas l’air de l’être pour tous

The Effects of Sodium Bicarbonate Ingestion on Exhaustive Bench Press Performance
Medicine & Science in Sports & Exercise:  May 2011 - Volume 43 - Issue 5 - pp 847-848     Page, Richard; Siegler, Jason C. FACSM
Sodium bicarbonate (NaHCO3) has been shown to be an effective ergogenic aid in attenuating to the deleterious perturbations in acid-base status associated with high intensity exercise. However, given the plethora of studies that exist only a limited number have assessed its efficacy in enhancing resistance exercise performance.
PURPOSE: To examine the effects of NaHCO3 supplement on exhaustive bench press performance after varying recovery times between sets.
METHODS: Eight resistance trained male subjects performed six single blind, randomized trials on the bench press (three sets at a constant load of 70% of one repetition maximum (RM), the final of which completed to failure with rest intervals of 60, 120 or 180 seconds (s) between sets) 120 minutes post NaHCO3 (0.3 g·kg-1) or placebo (NaCl, 0.045 g·kg-1) ingestion. Capillary blood samples were obtained pre and post ingestion, and following the final exhaustive set. All metabolic data were assessed via a two-way ANOVA and performance data by a three-way ANOVA, both with repeated measures.
RESULTS: Post hoc analysis revealed blood acid-base status (pH, bicarbonate [HCO3-] and base excess [BE]) was significantly elevated (p < 0.05) following NaHCO3 ingestion in comparison to placebo. Although significantly lower than pre exercise (p < 0.05), post trial pH, HCO3- and BE values remained elevated in the NaHCO3 treatments compared to placebo (p < 0.05). Subsequent analysis revealed no significant interaction or main effects for treatment on the number of reps performed to exhaustion during the final set (p > 0.05).

However, the number of reps performed during the final set to failure increased proportionally to the increasing length of the rest interval (60s: 8.4 ± 3.7, 120s: 11.4 ± 3.3, 180s: 12.9 ± 3.5 p < 0.05).

CONLUSION: Thus, although NaHCO3 attenuated metabolic acidosis, it had no effect on skeletal muscle contractile function or recovery intervals between sets.

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Gain de force n’est donc pas égal à gain de muscle

Effects of Training Volume on Strength and Hypertrophy in Sedentary Young Japanese Men
Medicine & Science in Sports & Exercise: May 2011 - Volume 43 - Issue 5 - p 837

Our knowledge of the effects of training volume on upper-limb strength and hypertrophy in crossover designs is rather limited.
PURPOSE: The purpose of the present crossover study was to investigate the effects of training volume on muscular strength and hypertrophy of the elbow flexor muscles (biceps brachii and brachialis) in sedentary young Japanese men.
METHODS: Eight subjects (age, 25.0 ± 2.1 years; body weight, 64.2 ± 7.9 kg; height, 171.7 ± 5.1 cm) were recruited for this study. The subjects trained their elbow flexor muscles twice per week for 12 consecutive weeks using a seated dumbbell preacher curl. Subjects’ dominant and non-dominant arms were randomly assigned to training with 1 or 3 sets of 10 reps per set. Rest intervals between sets were 60 s. The one-repetition maximum (1RM) of each arm was measured every 4 weeks to evaluate strength gains. Magnetic resonance imaging (MRI) was used to determine changes in the cross-sectional area (CSA) of the biceps brachii and brachialis at the beginning and end of a 12-week training period.
RESULTS: Percentage gains in strength were 20.4% ± 21.6% in the 1-set arm and 31.7% ± 22.0% in the 3-set arm, although no significant differences were observed between the two protocols. However, the 3-set protocol significantly increased CSA (1 set, 8.0% ± 3.7%; 3 sets, 13.3% ± 3.6%; p

).
CONCLUSIONS: Training volume effects hypertrophy, whereas it showed a slight tendency (p <.076) to effect strength during 12 weeks of training in sedentary population.

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The Effect Of Lactate On Proliferation And Differentiation Behaviour Of C2c12 And Primary Human Myoblasts
Medicine & Science in Sports & Exercise: May 2011 - Volume 43 - Issue 5 - p 411   Willkomm, Lena; Elsen, Manuela; Borosch, Sebastian; Jung, Raphael; Bloch, Wilhelm

Lactate (La) has long been considered as a waste product of energy metabolism and the cause of decrease in muscle pH and hence muscle fatigue. This idea has changed massively in the past. Now it is known that La is rather an intermediate of glucose metabolism as well as it has been termed Lactormon for it has signalling properties inducing gene expression for skeletal muscle adaptation. It has been shown to increase MCT content as well as to increase mitochondrial biogenesis. Such skeletal muscle adaptation is one of the major foci in sports medicine. Numerous adaptational mechanisms and signalling pathways have been described in the literature, investigating among other mechanical, metabolical, nutritional, and hormonal stimuli and their effects for the improvement of physiological functioning of skeletal muscle tissue. La, as a metabolic stimulus, has not yet been investigated extensively in this context.
PURPOSE: We investigated the effects of different lactate concentrations on the proliferation status and differentiation behaviour of C2C12 mouse immortal and primary human myoblasts.
METHODS: C2C12 mouse and primary human myoblasts were constantly incubated with differentiation medium containing different lactate concentrations (10 mM, 20 mM) at 37°C and 5% CO2 over a time period of 15 days. Cells were fixed using 4% PFA in PBS for immunocytochemical staining for Ki67, activated Caspase-3, F5D (myogenin) and Mf-20 (myosin heavy chain). Additionally, cell lysates were made for Western Blot analysis using the same markers as for immunostaining. Furthermore, we repeated the experiments with an intermittent incubation of 2 h every day to simulate a more realistic training situation.
RESULTS: Densitometrical analysis of cells stained for Ki67 showed a significant decrease if treated with La in a dose-dependent manner. Controversially, apoptotic induction by activated caspase-3 was increased if treated with La. Differentiation was shown to be delayed, but not decreased if cells received the La intervention.
CONCLUSION: Lactate seems to exhibit an inhibitory effect on the proliferation and apoptotic behaviour of C2C12 and primary human myoblasts. Furthermore, differentiation seems to be delayed but not reduced in a dose-dependent manner.

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Podcast de Michael Gundill

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