Short Rest Periods Research Articles

Effects of Elevated Circulating Hormones on Resistance Exercise-Induced Akt Signaling

Hormones and muscle contraction alter protein kinase B (Akt) signaling via distinct mechanisms. Therefore, the purpose of this study was to determine whether physiologically elevated circulating hormones modulate resistance exercise (RE)-induced signaling of Akt and its downstream targets. We hypothesized that elevated circulating hormones would potentiate the signaling response. Seven healthy men (mean +/- SD age, 27 +/- 4 yr; body mass, 79.1 +/- 13.6 kg; body fat, 16% +/- 7%) performed two identical lower-body RE protocols (five sets of five maximal repetitions of knee extensions) in a randomized order and separated by 1-3 wk: one protocol was preceded by rest [low-circulating hormonal concentration (LHC) trial], and the other was preceded by a bout of high-volume upper-body RE using short rest periods designed to elicit a large increase in circulating hormones [high-circulating hormonal concentration (HHC) trial]. The HHC trial invoked significantly (P < or = 0.05) greater growth hormone (GH) and cortisol concentrations compared with the LHC trial. There were minimal differences between trials in insulin and insulin-like growth factor-I (IGF-I) concentrations. Contrary to our hypothesis, 70-kDa ribosomal protein S6 kinase (p70 S6K) threonine (Thr) 389 phosphorylation within the vastus lateralis was attenuated at 180 min post-RE during the HHC trial. RE did not affect Akt or glycogen synthase kinase-3beta (GSK-3beta) phosphorylation nor were there differences between trials. Immediately post-RE, eukaryotic initiation factor (eIF) 4E binding protein-1 (4E-BP1) phosphorylation declined, and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation increased; however, there were no differences between trials in these variables. p70 S6K Thr 389 phosphorylation was attenuated during the HHC trial despite dramatically greater (>2.5-fold) circulating GH concentrations; this was potentially due to cortisol-induced inhibition of p70 S6K Thr 389 phosphorylation.

The Combined Acute Effects of Massage, Rest Periods, and Body Part Elevation on Resistance Exercise Performance

Although massage administered between workouts has been suggested to improve recovery and subsequent performance, its application between bouts of repetitive supramaximal anaerobic efforts within a given workout has received little attention. The purpose of the study compared different forms of very short rest periods administered between resistance exercise sets of individual workouts on subsequent performance. With a within-subjects design methodology, subjects (n = 30) performed three workouts that were identical in terms of the exercises (45 degrees leg press, prone leg curl, seated shoulder press, standing barbell curl), number of sets, and the resistance employed. For each workout, subjects received one of the following treatments between sets: 1 minute of rest as they stood upright, 30 seconds of rest as they stood upright, or 30 seconds of concurrent massage and body part elevation (MBPE), which entailed petrassage of the exercised limbs in a raised and supported position in an attempt to abate fatigue and enhance recovery from the previous set. Subjects were instructed to perform as many repetitions as possible for each set. For each exercise, two dependent variables were calculated: a total work/elapsed time ratio and the cumulative number of repetitions performed. For each exercise, one-way repeated-measures analysis of variance and Tukey's post hoc test revealed the following total work/elapsed time results: 1 minute rest <30 seconds' rest, 30 seconds' MBPE. For each exercise, cumulative repetition results were as follows: 1 minute rest >30 seconds' rest, 30 seconds' MBPE. Results imply that rest period duration exerts more influence on resistance exercise performance than MBPE. Those who seek improved resistance exercise performance should pay particular attention to rest period durations.

Mobilization and early hospital discharge for patients with acute myocardial infarction: literature review

OBJECTIVE: This study was a literature review with the purpose of analyzing articles comparing early and late mobilization and those comparing early and late discharge for patients with acute myocardial infarction. METHODS: The literature review was performed using the Lilacs and Medline databases (1966-2007), and the length of the resting period, the hospitalization and possible complications were analyzed. RESULTS: We selected 18 articles; 11 of them compared early and late mobilization and 7 compared early and late discharge. The length of the resting period in the early mobilization group varied from 2 to 10 days and 5 to 28 days for the longest resting period. The early discharge group stayed in the hospital from 3 to 14 days and the late discharge group stayed in the hospital from 5 to 21 days. CONCLUSION: The studies show that there is no evidence of complications related to short periods of bed rest and hospitalization.

RESEARCHES REGARDING FROST RESISTANCE AND BELATED SPRING FROST RESISTANCE OF SOME APRICOT TREE VARIETIES IN S D TIMISOARA CONDITIONS, UNDER CUTTINGS IN GREEN INFLUENCE

Trees spring passing from the rest period to intense biological activity brings trees frost resistance decrease. In case of the apricot tree, specie with short biological rest period, return frosts are very harmful after the un-tempering period, but especially spring belated frosts. Belated spring frosts catch trees in the phase with flowers or fruits barely formed, phase of maximum sensibility, which has an effect over yield diminution through fruits loss or fruits quality depreciation.

Fotossíntese foliar do capim-xaraés [Brachiaria brizantha (A. Rich.) Stapf. cv. Xaraés] e modelagem da assimilação potencial de dosséis sob estratégias de pastejo rotativo

Objetivou-se com este trabalho quantificar a fotossíntese foliar ao longo do período de rebrotação e modelar a fotossíntese de dosséis vegetativos em função da arquitetura foliar e do ambiente luminoso em pastagens de capim-xaraés [Brachiaria brizantha (A. Rich.) Stapf.] submetidas a estratégias contrastantes de pastejo rotativo. Na fase inicial de rebrotação, o potencial fotossintético foi pequeno, em média 10,4 µmol CO2 m-2 s-1 e, no tratamento de maior intervalo de pastejo (100% IL), esse potencial foi ainda menor (3,3 µmol CO2 m-2 s-1), o que pode comprometer o desenvolvimento das plantas. No dia médio (DM) do ciclo, ocorreram os maiores valores de fotossíntese foliar, em média 26 µmol CO2 m-2 s-1. No pré-pastejo, o tratamento 95%, que apresentou os menores intervalos de pastejo (22 dias), continuou com os maiores valores de fotossíntese foliar (26,1 µmol CO2 m-2 s-1). Enquanto isso, os tratamentos com maiores intervalos de pastejo (28 e 32 dias, respectivamente para o tratamento 28 dias e 100% IL) tiveram seus valores de fotossíntese foliar reduzidos (21,3 e 24,5 µmol CO2 m-2 s-1). No tratamento de maior freqüência de pastejo (95% de IL), o menor intervalo de pastejo e a manutenção de menor IAF médio (2,08) resultaram em maior entrada de luz no interior do dossel. O manejo adequado do capim-xaraés deve ser feito com intervalos de pastejo inferiores a 28 dias, a fim de possibilitar maiores valores de fotossíntese de dossel ao longo do ciclo de rebrotação.

Bed rest for acute uncomplicated myocardial infarction

Bed rest is prescribed to all patients with acute myocardial infarction (AMI), but to a variable extent. Current guidelines (American College of Cardiology/ American Heart Association) recommend at least 12 hours bed rest in patients with uncomplicated ST-elevation myocardial infarction, however the basis for this recommendation is unclear. To compare the effects of short versus longer bed rest in patients with uncomplicated AMI. We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2005), MEDLINE (January 1966 - August 2005), EMBASE (January 1988 - August 2005), PASCAL BioMed (January 1996 - August 2005); PsycINFO (January 1966 - August 2005) and BIOSIS Previews (January 1990 - August 2005). Randomised and quasi-randomised controlled trials of short versus longer bed rest in patients with uncomplicated AMI were sought. Study selection was performed independently by at least two investigators according to the predefined inclusion criteria. Data were extracted by two investigators independently and in duplicate. Authors were contacted to obtain missing information. We found 15 trials with 1487 patients assigned to a short period of bed rest (median 6 days) and 1471 patients assigned to longer bed rest (median 13 days). Generally the studies were outdated and appeared to be of moderate to poor methodological reporting quality. There was no evidence that shorter bed rest was more harmful than longer bed rest in terms of all cause mortality (RR=0.85 (95%CI 0.68 to 1.07), cardiac mortality (RR=0.81 (95%CI 0.54 to 1.19), or reinfarction (RR=1.07 (95%CI 0.79 to 1.44)). Bed rest ranging from 2 to 12 days appears to be as safe as longer periods of bed rest. The quality of most trials is unsatisfactory. Current bed rest recommendations are not supported by the existing evidence as the optimal duration of bed rest is unknown. The lack of adequate trials is surprising, considering the large size of several studies to compare effectiveness of drugs on people with AMI.

Effects of rest interval during high-repetition resistance training on strength, aerobic fitness, and repeated-sprint ability

The effect of altering the rest period on adaptations to high-repetition resistance training is not well known. Eighteen active females were matched according to leg strength and repeated-sprint ability and randomly allocated to one of two groups. One group performed resistance training with 20-s rest intervals between sets, while the other group employed 80-s rest intervals between sets. Both groups performed the same total training volume and load. Each group trained 3 days a week for 5 weeks [15- to 20-repetition maximum (RM), 2 – 5 sets]. Repeated-sprint ability (5×6-s maximal cycle sprints), 3-RM leg press strength, and anthropometry were determined before and after each training programme. There was a greater improvement in repeated-sprint ability after training with 20-s rest intervals (12.5%) than after training with 80-s rest intervals (5.4%) (P = 0.030). In contrast, there were greater improvements in strength after training with 80-s rest intervals (45.9%) than after training with 20-s rest intervals (19.6%) (P = 0.010). There were no changes in anthropometry for either group following training. These results suggest that when training volume and load are matched, despite a smaller increase in strength, 5 weeks of training with short rest periods results in greater improvements in repeated-sprint ability than the same training with long rest periods.

Morphological and pomological traits variability of almond genotypes from Slankamen hill population

Almond production in Serbia is much lower then needs and possibilities and its growing are limited on garden plots. Short period of biological rest is characteristic of almond tree. Because of that its growth can be successful only in some locations in Serbia. One of such places is Slankamen hill, where almost every garden plot has almond seedlings. Spontaneous almond population from Slankamen hill has great variability of morphological and pomological traits. After several years of visiting this location and evaluating of more than 300 almond seedlings, 20 genotypes with good and regular cropping have been selected. During the 2003-06, their morphological and pomological traits were examined. Description was given on the basis of almond descriptor (G?LCAN, 1985). The research, selection and collection of almond genotypes from this locality should contribute expansion of almond tree growing area in Serbia. Genotypes 1 and 19 with medium fruit and regular crop, as well as the late-blooming genotypes 29 and 13 were selected.

Effects of Short vs. Long Rest Period Between Sets on Elbow-Flexor Muscular Endurance During Resistance Trainingto Failure

This study aimed to examine short-term resistance training effects of resting period length between sets on maximal number of repetitions and mean velocity over a moderate-intensity (60% of the maximum voluntary isometric contraction [MVIC]) set to failure on elbow-flexor muscles. The MVIC and surface electromyographic activity (sEMG) were also measured. Twenty-one untrained subjects were divided into 3 groups: short rest between sets (1 minute; SR), long rest between sets (4 minutes; LR), and nontraining control group (CG). The SR and LR performed 3 sets to failure in an arm-curl machine, 2 days per week for 5 weeks, with moderate loads (60-75% of the MVIC). The LR completed a significantly higher (31.6%, p < 0.05) total training volume than the SR. Both training groups enhanced the maximal number of repetitions to failure, with no significant differences in the magnitude of gains. The posttraining average velocity achieved by the SR at 40, 50, 60, 70, 80, and 90% of the total number of repetitions completed was significantly higher (p < 0.05) than the corresponding average velocity achieved on pretraining conditions, whereas no significant differences were observed in the LR. No significant changes in the MVIC or sEMG were observed in any group. We conclude that short-term elbow-flexor resistance training to failure, allowing 1 or 4 minutes of rest between sets, induces similar gains concerning local muscular endurance. Nevertheless, only the SR training approach reduced the rate of decline in the average repetition velocity during a set to failure. This can be of some importance in sport modalities in which not only the maximal number of repetitions (e.g., muscle endurance), but also a greater maintenance of high repetition velocities, may be critical for performance.

Sensory – Motor control of ligaments and associated neuromuscular disorders

The ligaments were considered, over several centuries, as the major restraints of the joints, keeping the associated bones in position and preventing instability, e.g. their separation from each other and/or mal-alignment. This project, conducted over 25 years, presents the following hypothesis: 1. Ligaments are also major sensory organs, capable of monitoring relevant kinesthetic and proprioceptive data. 2. Excitatory and inhibitory reflex arcs from sensory organs within the ligaments recruit/de-recruit the musculature to participate in maintaining joint stability as needed by the movement type performed. 3. The synergy of the ligament and associated musculature allocates prominent role for muscles in maintaining joint stability. 4. The viscoelastic properties of ligaments and their classical responses to static and cyclic loads or movements such as creep, tension–relaxation, hysteresis and strain rate dependence decreases their effectiveness as joint restraint and stabilizers and as sensory organs and exposes the joint to injury. 5. Long-term exposure of ligaments to static or cyclic loads/movements in a certain dose-duration paradigms consisting of high loads, long loading duration, high number of load repetitions, high frequency or rate of loading and short rest periods develops acute inflammatory responses which require long rest periods to resolve. These inflammatory responses are associated with a temporary (acute) neuromuscular disorder and during such period high exposure to injury is present. 6. Continued exposure of an inflamed ligament to static or cyclic load may result in a chronic inflammation and the associated chronic neuromuscular disorder known as cumulative trauma disorder (CTD). 7. The knowledge gained from basic and applied research on the sensory – motor function of ligaments can be used as infrastructure for translational research; mostly for the development of “smart orthotic” systems for ligament deficient patients. Three such “smart orthosis”, for the knee and lumbar spine are described. 8. The knowledge gained from the basic and applied research manifests in new physiotherapy modalities for ligament deficient patients. Ligaments, therefore, are important structures with significant impact on motor control and a strong influence on the quality of movement, safety/stability of the joint and potential disorders that impact the safety and health of workers and athletes.

Self‐assessed quality of sleep, occupational health, working environment, illness experience and job satisfaction of female nurses working different combination of shifts

The aim of this study was to describe and compare the self-assessed quality of sleep, occupational health, working environment, illness experience and job satisfaction among female nurses working different combinations of shifts. Evidence from several studies indicates that there is an association between the disruption of the circadian cycle caused by shift work and adverse health effects. A cross-sectional design was used with a sample of 348 nurses drawn from the registry of the Icelandic Nurses' Association, representing 17% of the workforce of Icelandic nurses. A self-administered questionnaire, measuring occupational health, quality of sleep, the illness experience, job satisfaction and working environment was used. Data were analysed according to type of shift (days only, rotating days/evenings, rotating days/evenings/nights) by use of analysis of variance and chi-square. No difference was found between participants based on type of shift with regard to the illness experience, job satisfaction and quality of sleep. Nurses working rotating day/evening/night shifts reported a longer working day, more stressful environmental risk factors, more strenuous work and that they were less able to control their work-pace. In general, the nurses reported low severity of symptoms; however, nurses working rotating days/evenings shifts experienced more severe gastrointestinal and musculoskeletal symptoms when compared with others. This was explained by the short rest period provided for between evening and morning shifts. In general Icelandic nurses are satisfied with their work and their shift assignment does not seem to pathologically disrupt their circadian cycle. Nevertheless, nursing directors are advised to look more closely at the organization of nurses' work during night shifts, as well as the rest period for nurses changing from evening to day shifts.

Does blood flow restriction enhance hypertrophic signaling in skeletal muscle?

in the last decade, there was a dramatic increase in our knowledge of the molecular events that accompany changes in skeletal muscle mass in response to resistance exercise training or to chronic unloading. For example, the role of myostatin in limiting skeletal muscle growth during development was

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.

Trained Vs Untrained Hr And Bp Responses To High Intensity Resistance Exercise

Recently, high intensity (80% of 1 RM) resistance exercise (RE), in particular, has been shown to elicit post exercise hypotension (PEH) in normotensive individuals during separate upper and lower body training sessions (Simoes et al., 2004). It remains unclear whether PEH occurs in resistance trained (T) and untrained (UT) normotensive. PURPOSE To examine heart rate (HR) and blood pressure (BP) response during and after combined upper and lower body RE in resistance trained (continuous training for at least 6 weeks) and untrained (UT) normotensives. METHODS After 1 RM determination for bench press (BPr), leg press (LP), shoulder press, biceps curl, triceps pushdown (TP), lat pulldown, and leg curl (LC), ten T and ten UT college aged volunteers performed two sets of 8 to 10 RM at 75% of 1RM for each exercise in the above order. Two minutes rest was given between sets and different exercises with HR and BP recorded after the second set for upper body (BPr), lower body (LP) and the smaller accessory muscle groups (TP and LC). HR and BP were also recorded in the seated position at 10-minute intervals during recovery for 1 hour. RESULTS Trained subjects had a significantly (p<.05) greater 1 RM compared to UT for each of the exercises with the greatest differences in the lower extremity (LP: 538.6 ± 154.3 vs. 400.1 ± 78.4 lb) and the smallest difference in the triceps (TP: 104.5 ± 26.1 vs. 80.5 ± 16.4 lb). HR responses were not significantly (p>.05) different between UT and T groups for any of the measurement times. The highest HR occurred following LP in UT (159 ±11.1 bpm) and TP (161.2 ± 10.9 bpm) in the T. HR response for LP in T was 158 ± 16.6 bpm. Systolic BP was not significantly (p>.05) different for any of the measurement times between groups although within groups it was significantly (p<.05) different in response to the exercises (LP vs. LC for T: 142 ± 19.6 vs 117.2 ± 15.8 mmHg; LP vs. BP for UT: 145 ± 15.8 vs. 131.2 ± 10.8 mmHg). PEH was evident in both UT (mean ± SD =22 ± 6.6 mmHg drop in SBP from rest, n=7) and T (mean ± SD =24 ± 9.5 mmHg drop from rest, n=4). CONCLUSIONS Based on these results, PEH appears more common in UT than trained but still occurs in the trained. We speculate that short rest periods repeated over the course of a resistance training program contribute to PEH due to compromised vasoregulation.

Static Stretch And Warm-up

Stretching is generally recommended to prevent injury and to improve individual's performance. Many authors have demonstrated the thermal agents benefits on the flexibility enhancement. For instance, Williford et al. (1986) proposed stretching alone, i.e. without warm-up, for a better flexibility improvement. However, such stretching modality may be moot for some athletes due to the high stress on the musculoskeletal system. Therefore, warm-up followed by a short rest period prior to stretching seems to be more appropriate. PURPOSE Thus, we investigated the effects of a 5-weeks static stretch program following a warm-up interspersed or not with a 20-minutes rest period. The training-induced effects were examined on the lower-limb flexibility and vertical jumping ability. METHODS Ten physical education students volunteered to participate in this study. Five of them conducted the static stretches of the lower-limb immediately after 10 minutes warm-up (jogging). The remaining five performed the same stretching training after a 20-minutes rest period following the warm-up. Static stretch sessions consisted of four bilateral 30-second passive stretches of the quadriceps femoris, hamstring, adductor and calf muscles, conducted two times a week for five weeks. flexibility (i.e., range of motion) of the hamstring, adductor and calf muscles was measured before and after the stretch training using goniometry. Moreover, the explosive strength was assessed using vertical jump tests (squat jump and counter movement jump). Stretch effects were then analyzed using a two-way analysis of variance with repeated measures. RESULTS While no significant improvement was recorded for the vertical jump performance and the calf and adductor muscles flexibility, our results indicate a significant hamstring flexibility increase (P <0.05) after the 5-weeks period. Indeed, the right leg to hip angle (supine subject), exhibited 14.6 ± 6.2° and 11.0 ± 6.0° mean (± S.D.) increases respectively for the group with and without the resting period between warm-up and stretching. Nevertheless, these flexibility improvements were not different between groups. CONCLUSIONS Our results reveal that a 5-weeks stretch program is sufficient to improve the hamstring flexibility but not for calf and adductor muscles. Increasing either or both training duration and session number per week seems required to obtain a flexibility increase for these two muscle groups. Performing stretches after a rest period or immediately after the warm-up does not appear to significantly modify the effectiveness of static stretching. Finally, stretching does not improve jump height.

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.

Does hippocampus associate discontiguous events? Evidence from event‐related fMRI

To examine the hypothesis that the hippocampus is necessary to overcome temporal or spatial "discontiguity" (Wallenstein et al., Trends Neurosci 1998; 21:317-323), subjects were imaged by functional magnetic resonance imaging (fMRI) when they were making judgments as to whether two words were semantically related. Two words were presented, either at the same time (the Simultaneous Presentation Condition) or one after the other with a short unfilled rest period (the Delayed Presentation Condition). The latter condition, relative to the former, was proposed to involve the process of "discontiguity association." Event-related fMRI results of eight subjects showed that, relative to the binding of simultaneously presented words, the binding of delay presented words was associated with left hippocampus activity. This result provided direct neuroimaging evidence for the role of the hippocampus in "discontiguity association."

Short rest periods after static lumbar flexion are a risk factor for cumulative low back disorder

The objective of this work was to study the effect of rest periods of various durations applied between six 10-min sessions of static flexion on the development of cumulative low back disorder (CLBD). Three experimental groups of a feline model were used, and the rest duration between sequential static load periods was set to 5, 10, and 20 min, with a corresponding load-to-rest ratio of 2:1, 1:1 and 1:2, respectively. The reflex electromyographic (EMG) activity from the multifidus muscles and supraspinous ligament displacement (creep) were recorded during the flexion periods and over 7 h of rest following the load–rest cycles. It was found that a minor disorder developed in all the groups whereas a severe neuromuscular disorder including a delayed hyperexcitability was observed only in the group subjected to 5 min rest. The two-way ANOVA showed a significant effect of time post loading ( p < 0.001) and rest duration ( p < 0.001) on the Normalized Integrated EMG (NIEMG) recovery data; a significant effect of time post loading on the Displacement data ( p < 0.001) was observed as well. The post hoc Fisher test performed on the NIEMG data during the recovery phase showed a significant difference between the group subjected to 5 min rest and the other two groups ( p < 0.001). These results suggest that while a short rest period of 2:1 load-to-rest ratio leads to CLBD, longer rest at 1:1 and 1:2 load-to-rest ratio are more favorable for preventing or attenuating the development of CLBD. Short rest periods between sessions of static lumbar flexion, therefore, are a risk factor for the development of CLBD.

Blindness and brain plasticity: contribution of mental imagery?: An fMRI study

The purpose of this study was to study brain plasticity in the visual cortex, in six subjects totally blind from birth. The protocol we used was the same as that employed in a prior study on blindfolded sighted subjects (Brain Res., 924 (2002) 176). The production of mental images from animal names versus passive listening to abstract words, involved, in the early blind subjects as well as in the blindfolded sighted subjects of our control group, the superior occipital, inferior and superior parietal areas, premotor area, visual association. Activation foci in the somatosensory areas in the left hemisphere, as well as in the temporal and fusiform gyri were only visible in the blind subjects. The experiment, which was repeated after a short period of rest, demonstrated, this time again, predominant involvement of the dorsal pathway and activation of the primary visual area (in a region of interest). With respect to the ongoing debate on brain reorganization, our study shows that the primary visual area is activated in early blind subjects, and that activation persists in a mental imagery task involving no sensory input other than verbal instructions.

Evaluation of the reliability of two field hockey specific sprint and dribble tests in young field hockey players

Objectives: To determine the reliability of two field hockey specific tests: the shuttle sprint and dribble test (ShuttleSDT) and the slalom sprint and dribble test (SlalomSDT). Methods: The shuttle sprint...