scholarly journals Effects of creatine hydrochloride supplementation on physical performance and hormonal changes in soldiers

2021 ◽  
Vol 9 (1) ◽  
pp. 93-99
Author(s):  
Mohammad Milad Tayebi ◽  
Mitra Yousefpour ◽  
Laya Ghahari
Keyword(s):  
Physical Performance ◽  
Vertical Jump ◽  
Hormonal Changes ◽  
Power Performance ◽  
Mean Power ◽  
Wingate Anaerobic Test ◽  
Double Blind ◽  
Back Squat ◽  
Before And After ◽  
Army Soldiers

Purpose: The aim of this study was to examine the effects of 2 weeks of creatine hydrochloride (CrHCl) supplementation on physical performance and hormonal changes in army soldiers. Materials: Eighteen male army soldiers were randomly assigned in a double-blind fashion to either a CrHCl (n=9) or placebo (Pl) (n=9) groups. CrHCl group costumed 3g of creatine per day, whereas Pl group was given dextrose. Before and after supplementation period, the subjects performed a battery of performance tests including one repletion maximum (1RM) of bench press and back squat, vertical jump (VJ) and Wingate anaerobic test. In addition, blood samples were obtained to determine changes in testosterone and cortisol concentrations per and post supplementation. Results: There were significant increases in VJ, peak and mean power, and 1RM back squat test following the 2 weeks of CrHCl supplementation (p < 0.05) without any significant change for the Pl group. In addition significant changes were observed in testosterone and cortisol concentrations from before to after supplementation in CrHCl group (p < 0.05) and compared with Pl group (p=0.001). Conclusions: In conclusion, the present study indicates that CrHCl supplementation can improve VJ, power performance, 1RM back squat and hormonal changes in army soldiers.

Impact of Clomiphene Citrate on the Steroid Profile in Dysmetabolic Men with Low Testosterone Levels

2021 ◽  
Vol 53 (08) ◽  
pp. 520-528
Author(s):  
Carla Pelusi ◽  
Flamina Fanelli ◽  
Margherita Baccini ◽  
Giovanni De Pergola ◽  
Vincenzo Triggiani ◽  
...  
Keyword(s):  
Clomiphene Citrate ◽  
Serum Levels ◽  
Male Hypogonadism ◽  
Hormonal Changes ◽  
Double Blind ◽  
Adrenal Steroidogenesis ◽  
Steroid Profiling ◽  
Corticosteroid Binding Globulin ◽  
Before And After ◽  
17Β Estradiol

AbstractClomiphene citrate (CC) in male hypogonadism increases testosterone (T) and estrogen levels by stimulating pituitary gonadotropin release. Our group confirmed these hormonal changes in a randomized, cross-over, double-blind trial of CC versus placebo in addition to metformin, conducted in 21 obese dysmetabolic men with low T levels. However, we hypothesize that based on its mechanism of action, CC may directly or indirectly affect adrenal steroidogenesis. The aim of this sub-study was to better understand the changes in steroid levels and metabolism induced by CC treatment. We assessed 17α-hydroxypregnelone (17αOH-P5), dehydroepiandrosterone (DHEA), progesterone (P4), 17α-hydroxyprogesterone (17αOH-P4), androstenedione (A), T, dihydrotestosterone (DHT), estrone (E1), 17β-estradiol (E2), 11-deoxycortisol (11 S), cortisol (F), and cortisone (E) by LC-MS/MS, and corticosteroid binding globulin (CBG) by ELISA, before and after each treatment. In addition, free-F and steroid product/precursor ratios were calculated. We observed a significant change in serum levels induced by CC compared with placebo for 17αOH-P4, DHT, T, E2, E1, F, E, and CBG, but not free-F. In addition, compared to placebo, CC induced higher 17αOH-P4/P4, E2/E1, 17αOH-P4/17αOH-P5, A/17αOH-P4, T/A, E1/A, F/11 S, and F/E ratios. Therefore, besides the CC stimulating effect on testis steroidogenesis, our study showed increased F, E, but not free-F, levels, indicating changes in steroid metabolism rather than adrenal secretion stimulation. The steroid profiling also revealed the CC stimulation of the Δ5 rather than the Δ4 pathway, thus indicating considerable testicular involvement in the increased androgen secretion.

scholarly journals Repeated Menthol Mouth Swilling Affects Neither Strength nor Power Performance

Sports ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 90 ◽  
Author(s):  
Russ Best ◽  
Dani Temm ◽  
Holly Hucker ◽  
Kerin McDonald
Keyword(s):  
Repeated Measures ◽  
Vertical Jump ◽  
Average Power ◽  
Small Degree ◽  
Power Performance ◽  
Mean Power ◽  
Experimental Conditions ◽  
Jump Performance ◽  
Experimental Trials ◽  
And Control

This study aimed to assess the effects of repeated menthol mouth swilling upon strength and power performance. Nineteen (10 male) participants completed familiarisation and experimental trials of repeated menthol mouth swilling (0.1% concentration) or control (no swill) in a randomised crossover design. Participants performed an isometric mid-thigh pull (IMTP; peak and mean force; N), vertical jump (peak; cm) and six second sprint (peak and mean power; W) under each condition. Participants completed three efforts per exercise task interspersed with three-minute recoveries. Mean best values were analysed via a two-way mixed repeated measures ANOVA, and differences reported as effect sizes ± 95% confidence intervals, with accompanying descriptors and p values. Differences in peak IMTP values were unclear between familiarisation and experimental trials, and between menthol and control conditions. Mean IMTP force differed between familiarisation and control (0.51; −0.15 to 1.14; p = 0.001) and familiarisation and menthol conditions (0.50; −0.15 to 1.14; p = 0.002) by a small degree, but were unclear between control and menthol conditions. Unclear differences were also noted on vertical jump performance compared to familiarisation and between experimental conditions, with repeated six second peak and average power performance also showing unclear effects across all comparisons. We conclude that repeated menthol mouth swilling does not improve strength or power performance.

scholarly journals Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Javier Zaragoza ◽  
Grant Tinsley ◽  
Stacie Urbina ◽  
Katelyn Villa ◽  
Emily Santos ◽  
...  
Keyword(s):  
Physical Performance ◽  
Linear Models ◽  
Dynamic Testing ◽  
Collegiate Athletes ◽  
Performance Testing ◽  
The Body ◽  
Double Blind ◽  
Movement Accuracy ◽  
Beneficial Effects ◽  
Before And After

Abstract Background A limited amount of research has demonstrated beneficial effects of caffeine and theanine supplementation for enhancement of mental performance. The purpose of this investigation was to determine whether the acute ingestion of a supplement containing caffeine, theanine and tyrosine improves mental and physical performance in athletes. Methods Twenty current or former male collegiate athletes (age: 20.5 ± 1.4 y; height: 1.82 ± 0.08 m; weight: 83.9 ± 12.6 kg; body fat: 13.8 ± 5.6%) completed this randomized, double-blind, placebo-controlled crossover trial. After familiarization, each participant completed two identical testing sessions with provision of a proprietary dietary supplement (SUP) containing caffeine theanine and tyrosine or a placebo (PL). Within each testing session, participants completed assessments of mental and physical performance before and after provision of SUP or PL, as well as after two rounds of exercise. Assessments were performed using a performance testing device (Makoto Arena) that evaluated multiple aspects of mental and physical performance in response to auditory and visual stimuli. Testing was performed both with the body in a static position and during dynamic movement. General linear models were used to evaluate the effects of SUP and PL on performance. Results Changes in movement accuracy during performance assessment were greater following SUP ingestion as compared to PL for both static and dynamic testing (SUP: + 0.4 to 7.5%; PL: − 1.4 to 1.4% on average; p < 0.05). For dynamic testing, the change in number of targets hit was higher and the change in average hit time was lower with SUP as compared to PL (p < 0.05). However, there were no differences between conditions for the changes in number of targets hit or average hit time during static testing. There were no differences in changes of subjective variables during either condition, and performance measures during the two rounds of exercise did not differ between conditions (p > 0.05). Discussion The present results indicate that a combination of a low-dose of caffeine with theanine and tyrosine may improve athletes’ movement accuracy surrounding bouts of exhaustive exercise without altering subjective variables. Based on this finding, supplementation with caffeine, theanine and tyrosine could potentially hold ergogenic value for athletes in sports requiring rapid and accurate movements. Trial registration NCT03019523. Registered 24 January 2017.

scholarly journals The Effects of Plyometric Conditioning Exercises on Volleyball Performance with Self-Selected Rest Intervals

2021 ◽  
Vol 11 (18) ◽  
pp. 8329
Author(s):  
Michal Krzysztofik ◽  
Rafal Kalinowski ◽  
Aleksandra Filip-Stachnik ◽  
Michal Wilk ◽  
Adam Zajac
Keyword(s):  
Performance Enhancement ◽  
Lower Body ◽  
Mean Power ◽  
Back Squat ◽  
Specific Performance ◽  
Volleyball Players ◽  
Before And After ◽  
Ball Velocity ◽  
Mean Power Output ◽  
Rest Intervals

Post-activation performance enhancement remains a topic of debate in sport science. The purpose of this study was to examine the effects of lower-body plyometric conditioning activity (CA) with a self-selected intra-complex rest interval on upper and lower-body volleyball specific performance. Eleven resistance-trained female volleyball players participated in the study (age: 20 ± 2 years; body mass: 67.8 ± 4.4 kg; height: 178 ± 6 cm; half back squat one-repetition maximum: 78.6 ± 10.2 kg; experience in resistance training: 5.5 ± 2.1 years and in volleyball training: 10 ± 2.3 years). Each participant performed a plyometric CA followed by two different sport-specific tests: an attack jump and a standing spike attack. The changes in jump height (JH), relative mean power output (MP) and ball velocity (BV) were analyzed before and after the CA with self-selected rest intervals. The applied plyometric CA with self-selected intra-complex rest intervals led to an insignificant decline in JH (p = 0.594; effect size [ES]: −0.27) and MP (p = 0.328; ES: −0.46) obtained during the attack jump as well as a significant decline in BV (p = 0.029; ES: −0.72) during the standing spike attack. This study showed that a plyometric CA with self-selected intra-complex rest intervals failed to elicit localized and non-localized PAPE effect in a group of sub-elite volleyball players.

scholarly journals Combined but Not Isolated Ingestion of Caffeine and Taurine Improves Wingate Sprint Performance in Female Team-Sport Athletes Habituated to Caffeine

Sports ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 162
Author(s):  
Raci Karayigit ◽  
Alireza Naderi ◽  
Bryan Saunders ◽  
Scott C. Forbes ◽  
Juan Del Coso ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Mass ◽  
Perceived Exertion ◽  
Female Athletes ◽  
Team Sport ◽  
Mean Power ◽  
Wingate Anaerobic Test ◽  
Double Blind ◽  
Experimental Trials ◽  
Anaerobic Test

Previous studies have investigated caffeine (CAF) and taurine (TAU) in isolation and combined during exercise in males. However, the potential synergistic effect during high-intensity exercise remains unknown in female athletes. Seventeen female team-sport athletes participated (age: 23.4 ± 2.1 years; height: 1.68 ± 0.05 m; body mass: 59.5 ± 2.2 kg). All participants were habitual caffeine consumers (340.1 ± 28.6 mg/day). A double-blind randomized crossover design was used. Participants completed four experimental trials: (i) CAF and TAU (6 mg/kg body mass of CAF + 1 g of TAU), (ii) CAF alone; (iii) TAU alone; and (iv) placebo (PLA). Supplements were ingested 60 min before a 30-s Wingate Anaerobic Test (WAnT). Heart rate and blood lactate (BL) were measured before and immediately after the WAnT; and ratings of perceived exertion (RPE) were recorded immediately after the WAnT. Peak power (PP) was significantly higher following co-ingestion of CAF+TAU compared to PLA (p = 0.03) and TAU (p = 0.03). Mean power (MP) was significantly higher following co-ingestion of CAF+TAU compared to PLA (p = 0.01). No other differences were found between conditions for PP and MP (p > 0.05). There were also no observed differences in fatigue index (FI), BL; heart rate; and RPE between conditions (p > 0.05). In conclusion, compared to PLA the combined ingestion of 6 mg/kg of CAF and 1 g of TAU improved both PP and MP in female athletes habituated to caffeine; however; CAF and TAU independently failed to augment WAnT performance.

Micronutrient Fortified Carbohydrate Supplementation and Speed, Agility and Power in Indian Adolescent Athletes

2017 ◽  
Vol 54 (1) ◽  
pp. 1
Author(s):  
Tessa E. Morris ◽  
Rachana Bhoite ◽  
Ritu Karwal ◽  
, Verma ◽  
, Bhavna ◽  
...  
Keyword(s):  
Intermittent Exercise ◽  
Cycle Ergometer ◽  
Adolescent Athletes ◽  
Mean Power ◽  
Wingate Anaerobic Test ◽  
Performance Impact ◽  
Treatment Groups ◽  
Before And After ◽  
The Difference ◽  
Mean Power Output

The positive performance impact of exogenous carbohydrate intake on prolonged endurance is well established. The effect on shorter duration activities has been less documented, in particular with adolescents. In this randomized, cross over study, thirty adolescent athletes (24 male and 6 female; age: 13.5 ± 1.0 yrs; height: 161.4 ± 8.1cm; weight: 50.4 ± 9.3 kg) performed the same sequence of procedures; baseline assessments, a treatment drink before and after a 45 min intermittent exercise protocol followed by post-baseline assessments. Participants were randomised to one of three blinded treatment drinks; micronutrient fortified carbohydrate (CHO), calorie-matched control (PRO) or water (WAT). The assessments involved repeated sprint and repeated agility tests (6 repetitions; 65 sec. provided to complete the repetition and recover prior to the next effort) and a repeated Wingate anaerobic test (3 x 30 sec) on a cycle ergometer. The Fatigue Index (FI) was calculated from the sprint and agility results and Mean Power Output (MPO) from the repeated Wingate results. The difference between the baseline and post-baseline results was then calculated and CHO, PRO and WAT treatment groups compared using Analysis of variance (ANOVA). No significant differences were found between speed, agility and power change from baseline results when CHO, PRO and WAT treatment groups were compared (p ≥ 0.05). Supplementation with a micronutrient fortified carbohydrate beverage does not increase repeated speed, agility or power in Indian adolescent team sport athletes.

Four weeks of normobaric “live high-train low” do not alter muscular or systemic capacity for maintaining pH and K+ homeostasis during intense exercise

2012 ◽  
Vol 112 (12) ◽  
pp. 2027-2036 ◽  
Author(s):  
N. B. Nordsborg ◽  
C. Siebenmann ◽  
R. A. Jacobs ◽  
P. Rasmussen ◽  
V. Diaz ◽  
...  
Keyword(s):  
Placebo Group ◽  
Buffer Capacity ◽  
Maximal Exercise ◽  
Monocarboxylate Transporters ◽  
Intense Exercise ◽  
Mean Power ◽  
Double Blind ◽  
Before And After ◽  
Arterial Plasma ◽  
Sprint Ability

It was investigated if athletes subjected to 4 wk of living in normobaric hypoxia (3,000 m; 16 h/day) while training at 800–1,300 m [“live high-train low” (LHTL)] increase muscular and systemic capacity for maintaining pH and K+ homeostasis as well as intense exercise performance. The design was double-blind and placebo controlled. Mean power during 30-s all-out cycling was similar before and immediately after LHTL (650 ± 31 vs. 628 ± 32 W; n = 10) and placebo exposure (658 ± 22 vs. 660 ± 23 W; n = 6). Supporting the performance data, arterial plasma pH, lactate, and K+ during submaximal and maximal exercise were also unaffected by the intervention in both groups. In addition, muscle buffer capacity (in mmol H+·kg dry wt−1·pH−1) was similar before and after in both the LHTL (140 ± 12 vs. 140 ± 16) and placebo group (145 ± 2 vs. 140 ± 3). The expression of sarcolemmal H+ transporters (Na+/H+ exchanger 1, monocarboxylate transporters 1 and 4), as well as expression of Na+-K+ pump subunits-α1, -α2, and -β1 was also similar before and after the intervention. In conclusion, muscular and systemic capacity for maintaining pH and K+ balance during exercise is similar before and after 4 wk of placebo-controlled normobaric LHTL. In accordance, 30-s all-out sprint ability was similar before and after LHTL.

scholarly journals Passive Repetitive Isokinetic Training Compared with Resistance Training: Effects on Performance and Hormones in Untrained Men

2007 ◽  
Vol 13 (1) ◽  
pp. 20-28
Author(s):  
Shu Lin LEE ◽  
Chuan Show CHEN ◽  
Tzyy Yuang SHIANG ◽  
Mu San CHANG ◽  
Hsin I LO ◽  
...  
Keyword(s):  
Resistance Training ◽  
Vertical Jump ◽  
Performance Testing ◽  
Maximal Strength ◽  
Power Performance ◽  
Isokinetic Training ◽  
Strength Performance ◽  
Before And After ◽  
Traditional Resistance Training ◽  
Stretch Shortening Cycle

LANGUAGE NOTE | Document text in English; abstract also in Chinese. The purpose of this study was to investigate the effects of 10 weeks Passive Repetitive Isokinetic Training (PRI) training on hormone concentrations and physical performance. Nineteen untrained men were randomized to intervention with either PRI training (n=10) or traditional resistance training (n=9). PRI group performed five sets with ten repetitions with corresponding 70-75% repetition maximum (RM) loads on the PRI platform and 2-min rest periods, whereas TR group performed the same protocol with squat exercise. Strength and power performance testing were measured before and after 10-week training. Resting hormones were measured at pre-training (week-0), week-6, and post training (week-10). The results of our study were that after 10 weeks of PRI training, vertical jump, running vertical jump, 30-m sprint time and maximal strength by squat-test were significantly higher with respect to pre-training (p<0.05). In TR group, maximal strength by squatting test was significantly increased compared with pre-training (p<0.05), while no significantly changes were observed for the other power tests. There were no significantly changes in GH, IGF-1, testosterone, cortisol, and T/C ratio during the 10-week training period in both groups. The data indicated that PRI and traditional resistances training have similar hormonal states. The PRI training significantly increased power and strength performance. 被動反覆衝擊式訓練(Passive Repetitive Isokinetic Training；PRI)主要是依據伸展縮短循環(Stretch-Shortening-Cycle)特性所發展出的一種訓練肌力和爆發力的器材，然而PRI訓練對訓練效果及人體體內荷爾蒙的影響，尚無相關的實驗數值來證實。因此，本研究目的在探討PRI訓練前後安靜期血液中荷爾蒙之變化及肌力與爆發力等運動表現的影響。研究中共有19名受試者，隨機分為PRI訓練組(n=10)及傳統蹲舉訓練組(TR；n=9)，進行每週三次共10週之訓練，並於訓練前、訓練第6週及訓練後分別進行安靜時的血液採集，分析安靜時血液中生長激素(Growth hormone；GH)、類胰島素生長因子(Insulin-likc growth factor)、睪固酮(Testosterone)及皮質醇(Cortisol)的濃度我於訓練前後進行肌力及爆發力測試，結果發現：PRI組其肌力及爆發力表現在訓練後顯著的提升，而TR組僅增加最大肌力，兩組間以變化百分比進行比較：PRI在肌力及爆發力的變化百分比皆顯著高於TR組。血液荷爾蒙的結果：第6週和第10週時之安靜生長激素、類胰島素生長因子、睪固酮及皮質醇的濃度，組內訓練前後相比並無顯著性的改變；PRI組與TR組兩組間安靜期的荷爾蒙濃度反應亦無差異。由本研究得知：為期10週之PRI訓練能有效的提升肌力以及爆發力之運動表現，然而安靜期的荷爾蒙於訓練前、中、後並無顯著的變化。

Optimal Peak and Mean Power on the Wingate Test: Relationship with Sprint Ability, Vertical Jump, and Standing Long Jump in Boys

2000 ◽  
Vol 12 (4) ◽  
pp. 349-359 ◽  
Author(s):  
Khalid S. Almuzaini
Keyword(s):  
Body Mass ◽  
Pearson Correlation ◽  
Vertical Jump ◽  
Correlation Coefficients ◽  
Mean Power ◽  
Wingate Anaerobic Test ◽  
Performance Tasks ◽  
Standing Long Jump ◽  
Long Jump ◽  
Braking Force

The first purpose of the present study was to test sensitivity of the Wingate anaerobic test (WAnT) to alterations in resistance settings. The second purpose was to investigate whether using optimal braking force on WAnT enhances its relation with a 50-m dash, a vertical jump (VJ), or a standing long jump (LJ) tests. Twenty-three 12 year-old boys performed a 50-m dash, VJ, LJ, and WAnT using four braking force resistances (BFR; .065, .070, .075, and .080 kp/kg BM). Results revealed significant (p ≤ .05) differences among the four BFRs in peak power (PP) and in mean power (MP). Post hoc tests indicated significant differences among all of the four BFRs in PP and between the 0.065 and both the 0.075 and the 0.08 kp/kg BM in MP. Results of Pearson correlation coefficients indicated that using the optimal BFR for both PP and MP enhanced their relation with performance during the 50-m dash, VJ, and LJ tests. Also, partial correlation coefficients, controlling for body weight, height, percent fat, or body mass index supported these findings. It was concluded that for untrained, healthy 12-year-old boys, WAnT is sensitive to incremental alterations in resistance settings ranging from 0.065 to 0.080 kp/kg body mass. To be more specific, PP is sensitive to small increments in BFR, while MP is only sensitive to larger increments in BFR. Furthermore, optimizing resistance settings on WAnT enhances its relationship with anaerobic performance tasks, such as the 50-m dash, the VJ, and the LJ.

scholarly journals Effects of Caffeine Supplementation on Power Performance in a Flywheel Device: A Randomised, Double-Blind Cross-Over Study

Nutrients ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 255 ◽  
Author(s):  
Daniel Castillo ◽  
Raúl Domínguez ◽  
Alejandro Rodríguez-Fernández ◽  
Javier Raya-González
Keyword(s):  
Inertial Load ◽  
Power Performance ◽  
Mean Power ◽  
Placebo Condition ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Squat Exercise ◽  
Ergogenic Effects ◽  
The Mean ◽  
Double Blind Design

Despite the demonstrated evidence of the importance of eccentric contractions in sports performance, no research has evaluated the ergogenic effects of caffeine on this type of contraction means during flywheel exercises. Therefore, the aims of the present study were to compare the power outcomes, using different inertial loads, between caffeine and placebo conditions. Twenty-four young, healthy, and active men (age: 22.5 ± 4.8 years) took part in the study. A crossed, randomised double-blind design was used to analyse the effects of caffeine on lower limb power outcomes during a flywheel half-squat exercise. Participants completed four sets of eight all-out repetitions with a fixed three-minutes rest interval, and each set was performed using different inertial loads (i.e., 0.025, 0.050, 0.075 and 0.100 kg·m−2). Both the mean power (MP) and peak power (PP) in concentric (CON) and eccentric (ECC) movement phases at each inertial load were recorded after participants were administered either a caffeine supplement (6 mg·kg−1) or placebo (sucrose). Participants receiving a caffeine supplementation demonstrated improvements versus the placebo in total MP (MPtotal), as well as MP in CON phase (MPcon) and in ECC phase (MPecc) at each inertial load (22.68 to 26.53%; p < 0.01, effect size (ES) = 0.89–1.40). In addition, greater improvements with caffeine ingestion were obtained with respect to the placebo condition (18.79 to 24.98%; p < 0.01, ES = 1.03–1.40) in total PP (PPtotal), as well as PP in CON phase (PPcon) and in ECC phase (PPecc) at each inertial load. Thus, the supplementation of 6 mg·kg−1 caffeine may be considered to maximise on-field physical performance in those sports characterised by high demands of resistance.

Sign in / Sign up

Export Citation Format

Share Document