Effects of short and long inter-set rest on maximal isokinetic strength at slow and fast angular velocities in trained young males after eight weeks of resistance training

Resistance training is a widely used method to enhance muscle strength, with acute program variables influencing muscle adaptations. This study focused on the often-neglected variable of inter-set rest interval duration and its impact on muscle strength gains. Existing literature presents conflicting findings, with some studies advocating for longer rest intervals, while the others show comparable strength increases with shorter rests. Methodological differences in prescription and sample groups contributed to these inconsistencies. This study investigated the effect of short and long inter-set rests on maximal isokinetic strength gains of the upper and lower extremities during slow and fast angular velocities after eight weeks of resistance training. The research involved 26 healthy strength-trained males (age=20±1 year, body mass=81.5±8.8 kg, body height=184.4±6.1 cm) randomly assigned to G1m (1-minute rest) or G3m (3-minute rest). The resistance training programs were matched for all acute program variables, emphasizing the rest interval as the primary difference. Isokinetic dynamometry pre- and post-training assessed knee and elbow extensor and flexor maximal strength at 60º/s and 120º/s. The training program consisted of seven exercises performed at 70% 1RM until muscle failure three times per week over eight weeks. The most important result was that G3m, in contrast to G1m, led to a higher increase in peak torque of the knee (p=.037) and elbow extensors (p=.007) as well as the elbow flexors (p=.045) at 60º/s. Furthermore, G3m and G1m similarly increased the peak torque of the knee and elbow extensors and flexors at 120º/s and of the knee flexors at 60º/s (p>.138). In conclusion, the study suggests that strength training with longer inter-set rest intervals may lead to similar strength gains as strength training with shorter inter-set rest intervals. Nonetheless, individuals who prioritize maximizing their strength gains are advised to utilize longer rest intervals. However, shorter rest intervals may still yield significant strength enhancements, particularly for those who are limited by time

Relationship between knee extensor muscle strength and movement performance: the effect of load and body size

The main aim of the present study was to evaluate the effect of external loading on the relationship between leg muscle strength and vertical jump performance. Sixty-six physically active men performed maximal countermovement jumps (CMJ) under five loading conditions: body weight (BW), negative loads (85% BW and 70% BW) and positive loads (115% BW and 130% BW), on a force plate. CMJ was followed by the measurement of subjects’ maximal concentric knee extension torque at 60ºs-1 by an isokinetic dynamometer. The relationship between knee extensor strength and jumping performance with various loads was assessed by Pearson’s correlation coefficients and partial correlation coefficients after controlling for body mass. Knee extensor muscle strength correlated significantly (r=.78-.79; all p<.01) with peak power output during CMJ under all loading conditions. Considerably lower correlation coefficients (r=.18-.43; p=.01-.15) were observed between knee extensor strength and CMJ height under all loading conditions, which tended to be higher after the effect of body mass had been removed (r=.37-.51; all p<.01). These results contradict the general belief that an increase in external load is associated with the increased role of leg muscle strength in maximizing power output and jump height. Furthermore, the results suggest that relative strength is a better predictor of jumping performance than absolute strength, independently of external loads used

Osnove trreninga s otporom

Treningu s otporom u posljednjih dvadesetak godina znatno raste popularnost. To je oblik tjelesne aktivnosti koji se tradicionalno percipirao kao sastavni dio programa treninga ograničenih na vrhunske sportaše, bodybuildere i dizače utega koji nastoje poboljšati svoje izvedbe. Međutim, ta koncepcija više nije istinita. Opsežna istraživanja otkrivaju da je trening s otporom ne samo učinkovita metoda za poboljšanje mišićne izdržljivosti, jakosti i snage, nego i za poboljšanje zdravstvenog stanja većine pojedinaca, a ne isključivo natjecateljskih sportaša. Iako je do sada objavljen veliki broj knjiga i priručnika koji prikazuju razne vježbe s otporom za različite mišiće i mišićne skupine, nedostaje priručnik u kojem se detaljno opisuje metodski postupak uz prikaz niza slika karakterističnih struktura gibanja, položaja tijela, namještanja utega i trenažera prilikom izvedbe pravilne tehnike neke vježbe. Stoga je namjera autora ovog priručnika bila prikupiti i prikazati što veći broj različitih vježbi za razvoj mišićne izdržljivosti, jakosti i snage, njihovu pravilnu izvedbu po fazama, moguće varijante i tipične greške te ih kategorizirati s obzirom na mišićnu skupinu i vrstu otpora s kojom se izvode. Priručnik je stoga primjeren početnicima za samostalno učenje sadržaja, iako je prvenstveno namijenjen edukaciji stručnjaka iz područja fitnesa, ali i drugim stručnjacima u području kineziologije, trenerima i sportašima. Prvi dio priručnika opisuje osnove treninga s otporom i njegove dobrobiti te prikazuje hipotetski model razvoja mišićne izdržljivosti, jakosti i snage, dok se drugi dio odnosi na prikaz vježbi s vlastitom tjelesnom masom, slobodnim utezima, bučicama i na trenažerima

Eksploatacija geotermalne energije

S obzirom na sve veću cijenu fosilnih goriva, a i zagađenje okoliša njihovom upotrebom, sve se intenzivnije koriste obnovljivi izvori energije kao što su Sunčeva energija, energija vode, vjetra, biomase te geotermalna energija. U ovom će radu biti obrađena geotermalna energija i njezina upotreba u svrhu proizvodnje električne energije i grijanja kućanstva. Prvi dio rada opisuje samo nastajanje geotermalne energije kao obnovljivog izvora, područja s najvećim geotermalnim potencijalom, temperaturni gradijent i upotreba geotermalne energije u različite svrhe. U drugom dijelu rada obrađene su vrste geotermalnih elektrana, dijelovi od kojih se sastoje i njihov princip rada. Također su obrađene toplinske pumpe, njezini dijelovi, prednosti i mane određenih pumpi te je na jednom primjeru prikazana godišnja ušteda obiteljske kuće u odnosu na grijanje na plin. Na završetku rada napravljen je kratak osvrt na geotermalnu tehnološku inovaciju i razvoj ulaganja u geotermalnu elektranu

Osnove trreninga s otporom

Treningu s otporom u posljednjih dvadesetak godina znatno raste popularnost. To je oblik tjelesne aktivnosti koji se tradicionalno percipirao kao sastavni dio programa treninga ograničenih na vrhunske sportaše, bodybuildere i dizače utega koji nastoje poboljšati svoje izvedbe. Međutim, ta koncepcija više nije istinita. Opsežna istraživanja otkrivaju da je trening s otporom ne samo učinkovita metoda za poboljšanje mišićne izdržljivosti, jakosti i snage, nego i za poboljšanje zdravstvenog stanja većine pojedinaca, a ne isključivo natjecateljskih sportaša. Iako je do sada objavljen veliki broj knjiga i priručnika koji prikazuju razne vježbe s otporom za različite mišiće i mišićne skupine, nedostaje priručnik u kojem se detaljno opisuje metodski postupak uz prikaz niza slika karakterističnih struktura gibanja, položaja tijela, namještanja utega i trenažera prilikom izvedbe pravilne tehnike neke vježbe. Stoga je namjera autora ovog priručnika bila prikupiti i prikazati što veći broj različitih vježbi za razvoj mišićne izdržljivosti, jakosti i snage, njihovu pravilnu izvedbu po fazama, moguće varijante i tipične greške te ih kategorizirati s obzirom na mišićnu skupinu i vrstu otpora s kojom se izvode. Priručnik je stoga primjeren početnicima za samostalno učenje sadržaja, iako je prvenstveno namijenjen edukaciji stručnjaka iz područja fitnesa, ali i drugim stručnjacima u području kineziologije, trenerima i sportašima. Prvi dio priručnika opisuje osnove treninga s otporom i njegove dobrobiti te prikazuje hipotetski model razvoja mišićne izdržljivosti, jakosti i snage, dok se drugi dio odnosi na prikaz vježbi s vlastitom tjelesnom masom, slobodnim utezima, bučicama i na trenažerima

Social diversity in light of the inclusiveness of homosexually-oriented members of the Slovenian armed forces

Članek prinaša v Slovenijo prvo vojaško soci ološko raziskavo o inkluzivnosti istospolno usmerjenih pripadnic in pripadnikov v Slovensko vojsko. Na pod lagi fokusiranih strukturiranih intervjujev smo pro blematiko proučili z obeh zornih kotovs socialnega (percepcije lezbijk in gejev) in institucionalnega vidika (percepcije Slovenske vojske). Raziskava je pokazala, da so v pretežno heteronormativnem okolju istospolno usmerjene pripadnice in pripadniki Slovenske vojske – kljub varstvu dostojanstva in integritete – izpostavljeni različnim oblikam verbalne diskriminacije, nezaupa nje v disciplinske organe institucije pa jim vzbuja strah pred razkritjem istospolne usmerjenosti. Potreba po razpravljanju o tej dokaj tabuizirani problematiki je očitna, kot je nujno prepoznavanje prednosti socialne diverzitete v sodobnih vojaških organizacijahThe article brings to Slovenia the first military sociological research on the inclusion of homosexual members in the Slovenian Armed Forces (SAF). Based on focused structured interviews, we studied the issue from two standpoints: the social (perception of lesbians and gays) and institutional aspect (perception of the SAF). The research showed that in a largely heteronormative environment, homosexual members of the SAF are exposed to various forms of verbal discrimination, despite the formal protection of their dignity and integrity. The need to discuss this quite taboo issue is obvious, as is the need to acknowledge the benefits of social diversity in modern military organisation

Bilateral sequential motor cortex stimulation and skilled task performance with non-dominant hand

Objective: To check whether bilateral sequential stimulation (BSS) of M1 with theta burst stimulation (TBS), using facilitatory protocol over non-dominant M1 followed by inhibitory one over dominant M1, can improve skilled task performance with non-dominant hand more than either of the unilateral stimulations do. Both, direct motor cortex (M1) facilitatory non-invasive brain stimulation (NIBS) and contralateral M1 inhibitory NIBS were shown to improve motor learning. Methods: Forty right-handed healthy subjects were divided into 4 matched groups which received either ipsilateral facilitatory (intermittent TBS [iTBS] over non-dominant M1), contralateral inhibitory (continuous TBS [cTBS] over dominant M1), bilateral sequential (contralateral cTBS followed by ipsilateral iTBS), or placebo stimulation. Performance was evaluated by Purdue peg-board test (PPT), before (T0), immediately after (T1), and 30 min after (T2) an intervention. Results: In all groups and for both hands, the PPT scores increased at T1 and T2 in comparison to T0, showing clear learning effect. However, for the target non-dominant hand only, immediately after BSS (at T1) the PPT scores improved significantly more than after either of unilateral interventions or placebo. Conclusion: M1 BSS TBS is an effective intervention for improving motor performance. Significance: M1 BSS TBS seems as a promising tool for motor learning improvement with potential uses in neurorehabilitation

Transcranial magnetic stimulation has no placebo effect on motor learning

Objective: Motor learning is the core cognitive function in neurorehabilitation and in various other skill-training activities (e. g. sport, music). Therefore, there is an increasing interest in the use of transcranial magnetic stimulation (TMS) methods for its enhancement. However, although usually assumed, a potential placebo effect of TMS methods on motor learning has never been systematically investigated. Methods: Improvement of performance on the Purdue Pegboard Task over three test-blocks (T0, T1, and T2), separated by gt 20 min, was used to evaluate motor learning. In Experiment-1, two groups of 10 participants each were compared: one group immediately before T1 received a sham intermittent theta burst stimulation procedure (P-iTBS group), while another did not have any intervention at all (control - CON group). In Experiment-2, a third group of participants (six subjects) who received sham high-frequency repetitive TMS procedure before T1 (P-rTMS group) was compared with P-iTBS group. Results: All three groups showed significant learning over time, but without any difference between them, either in Experiment-1 between P-iTBS and CON, or in Experiment-2 between P-rTMS and P-iTBS. Conclusion: The results suggest lack of any placebo effect of TMS on motor learning. Significance: The results may help in designing further TMS-motor learning studies and in interpreting their results

Variations in polyamine conjugates in maize (Zea mays L.) seeds contaminated with aflatoxin B1: a dose–response relationship

BACKGROUND: Cereal seeds, such as maize seeds, are frequently contaminated with aflatoxin B1 (AFB1), one of the most dangerous naturally occurring carcinogens. In plants, phenolamides are involved in biotic stress response. The data on variations of phenolamides in AFB1-containing seeds are limited. RESULTS: Five polyamine conjugates, including two spermidine and three putrescine conjugates, were tentatively identified in methanolic extracts, using HPLC-DAD-MS. The ratio of putrescine to spermidine conjugates changed with increasing AFB1 concentration in a logistic dose–response manner, with a ratio of below 1 up to a concentration of 51.51 μg kg−1, and approximately 2.54 and 3 at higher concentrations of 177.4 and 308.13 μg kg−1, respectively. The observed variations of the total antioxidant activity and the total phenolic content may support this biphasic behaviour of the seeds against AFB1 stress. CONCLUSIONS: The obtained data are a contribution to the understanding of the roles of polyamine conjugates in seed defence to increasing AFB1 concentrations. According to our knowledge, this study reports for the first time the biphasic response of maize seeds to increasing AFB1 contamination level, comprising the induction of polyamine conjugate accumulation and variation in the ratio of conjugates. This dose–response relationship may provide useful information in the field of agricultural and food chemistry as an indicator of AFB1 contamination level and, hence, for selecting an appropriate seed quality

Sport-Specific Warm-Up Attenuates Static Stretching-Induced Negative Effects on Vertical Jump But Not Neuromuscular Excitability in Basketball Players

The purpose of this study was to examine the acute effects of static stretching (SS) and dynamic stretching (DS), alone and in combination with specific basketball warm-up (SBWU), on the neuromuscular excitability and vertical jump height in basketball players. Twelve healthy young male basketball players participated in the study (18 +/- 0.42 years; 17.4 - 18.6 age range; 188 +/- 9 cm; 76.5 +/- 9 kg). All participants completed two different stretching treatments (static and dynamic), performed on different days at least seven days apart, in the same period of training microcycle, in a counterbalanced order. Each session consisted of a self-paced jogging warm-up, followed by a 10-minute testing period (T0), which involved eliciting H reflex and M waves, followed by three trials of a vertical jump test. Participants then performed one of the treatment protocols. After another test (T1), participants conducted 8-minute specific basketball warm-up and then one more test (T2). Combined 3 (time) x 2 (stretching protocol) analysis of variance with repeated measures on both factors revealed that SS significantly decreased spinal excitability (H/M ratio) (p = 0.015, d = -0.38, percentage of change = -20.55%) and vertical jump height (p = 0.007, d = -1.91, percentage of change = -2.6%), but after SBWU, vertical jump height increased (p = 0.006, d = 1.13, percentage of change = 3.01%), while H/M ratio continued decreasing (p = 0.019, d = -0.45, percentage of change = -30.23%). Acute effects of DS, alone and in combination with SBWU were not significant. It seems that SBWU attenuates negative acute effects of SS on vertical jump performance in young basketball players, while DS appears to cause no significant acute effect for this population