MyMedR

Displaying publications 141 - 150 of 150 in total

Abstract:

Sort:

Short-Term Heat Acclimation and Precooling, Independently and Combined, Improve 5-km Time Trial Performance in the Heat

James CA, Richardson AJ, Watt PW, Willmott AGB, Gibson OR, Maxwell NS

J Strength Cond Res, 2018 May;32(5):1366-1375.
PMID: 28486332 DOI: 10.1519/JSC.0000000000001979

James, CA, Richardson, AJ, Watt, PW, Willmott, AGB, Gibson, OR, and Maxwell, NS. Short-term heat acclimation and precooling, independently and combined, improve 5-km time trial performance in the heat. J Strength Cond Res 32(5): 1366-1375, 2018-Following heat acclimation (HA), endurance running performance remains impaired in hot vs. temperate conditions. Combining HA with precooling (PC) demonstrates no additive benefit in intermittent sprint, or continuous cycling exercise protocols, during which heat strain may be less severe compared to endurance running. This study investigated the effect of short-term HA (STHA) combined with mixed methods PC, on endurance running performance and directly compared PC and HA. Nine amateur trained runners completed 5-km treadmill time trials (TTs) in the heat (32° C, 60% relative humidity) under 4 conditions; no intervention (CON), PC, short-term HA (5 days-HA) and STHA with PC (HA + PC). Mean (±SD) performance times were; CON 1,476 (173) seconds, PC 1,421 (146) seconds, HA 1,378 (116) seconds and HA + PC 1,373 (121) seconds. This equated to the following improvements versus CON; PC -3.7%, HA -6.6% and HA + PC -7.0%. Statistical differences were only observed between HA and CON (p = 0.004, d = 0.68, 95% CI [-0.27 to 1.63]) however, similar effect sizes were observed for HA + PC vs. CON (d = 0.70, 95% CI [-0.25 to 1.65]), with smaller effects between PC vs. CON (d = 0.34, 95% CI [-0.59 to 1.27]), HA vs. PC (d = 0.33, 95% CI [-0.60 to 1.26]) and HA + PC vs. PC (d = 0.36, 95% CI [-0.57 to 1.29]). Pilot testing revealed a TT typical error of 16 seconds (1.2%). Precooling offered no further benefit to performance in the acclimated individual, despite modest alleviation of physiological strain. Maintenance of running speed in HA + PC, despite reduced physiological strain, may indicate an inappropriate pacing strategy therefore, further familiarization is recommended to optimize a combined strategy. Finally, these data indicate HA, achieved through cycle training, yields a larger ergogenic effect than PC on 5-km running performance in the heat, although PC remains beneficial when HA is not possible.

Matched MeSH terms: Athletes
Impact of back squat training intensity on strength and flexibility of hamstring muscle group

Shariat A, Lam ETC, Shaw BS, Shaw I, Kargarfard M, Sangelaji B

J Back Musculoskelet Rehabil, 2017;30(3):641-647.
PMID: 28372315 DOI: 10.3233/BMR-160526

STUDY DESIGN: True experimental design.
BACKGROUND: The back squat is an integral aspect of any resistance training program to improve athletic performance. It is also used for injury prevention of the lower limbs.
OBJECTIVE: The purpose of this study was to examine the effect of back squat training at different intensities on strength and flexibility of the hamstring muscle group (HMG).
METHODS: Twenty-two male recreational bodybuilders with at least two years of experience in resistance training were recruited to participate in a nine-week training program. They were randomly assigned to a heavy back squat group (90-95% of one repetition maximum) or a moderate-intensity back squat group (60-65% of one repetition maximum).
RESULTS: The heavy back squat group resulted in a significantly (p < 0.001) increased in one repetition maximum strength but a significant (p < 0.001) reduction in HMG flexibility when compared to their counterparts. The results of the study indicate that while a heavy back squat training program is effective in improving strength, it has an adverse effect on the flexibility of the HMG.
CONCLUSION: The implication of this study is that there is a tradeoff between strength and flexibility and trainers should select the appropriate training protocols for their athletes to maximize athletic performance.

Matched MeSH terms: Athletes
Fulltext Anthropometric correlates of motor performance among Malaysian university athletes

Saidon Amri, Aris Fazil Ujang, Mohd Rozilee Wazir Norjali Wazir, Ahmad Naim Ismail

Movement Health & Exercise, 2012;1(1):75-92.
MyJurnal

The purpose of this study was to investigate the relationship between anthropometric and motor performance and to determine the contribution of combined anthropometric dimensions on motor performance. A total of 225 male (n = 138) and female (n = 87) Malaysian university athletes aged
between 18 and 28 years (M = 22.1, SD = 1.8) from 18 different team related sports and individual sports participated in this study. The subjects underwent anthropometric measurements (height, weight, BMI,% body fat, waist-hip ratio) and motor performance tests (grip strength - GS, back
strength - BS, 7 level sit-up - SU7, 10m sprint - S10, 30m sprint - S30, sit and reach - SR, trunk extension test - TE, SEMO agility test - SEMO, vertical jump - VJ, standing long jump - SLJ, reaction time (audio) - RTa, reaction time (visual) - RTv, bleep test - Bleep, leg strength - LS, stork test– ST, and push-ups - PU). Descriptive analysis showed that anthropometric and performance difference between sports reflected the needs and requirements of the sports. Multivariate Analysis of Covariance (MANCOVA) and multiple regression analysis showed that height, weight, BMI, % body fat, waist-hip ratio contributed positively or negatively on specific components of motor performance. Among male athletes, all anthropometric were found to be a significant contributor to strength, vertical jump, cardiovascular endurance, while among females, only % body fat and WHR contributed significantly to abdominal strength, vertical jump and trunk extension. Findings of the study suggested that anthropometric characteristics that contributed to motor performance should provide a scientific rationale in selecting and training of athletes.

Matched MeSH terms: Athletes
Fulltext Sports Courage in Malaysian Silat Athletes: Confirmatory Factor Analysis of the Malay Language Version

Hidrus AB, Kueh YC, Arifin WN, Konter E, Kuan G

Int J Environ Res Public Health, 2020 03 06;17(5).
PMID: 32155904 DOI: 10.3390/ijerph17051736

Sports courage is one of the most important attributes to help competitive athletes overcome anxiety, nervousness, and other psychological obstacles, but this field of study is still being overlooked by most athletes and coaches. The purpose of this study is to validate the Malay language version of the Sports Courage Scale (SCS-M) for Silat athletes using confirmatory factor analysis (CFA). Data were collected during 9th UPSI International Pencak Silat Championship in Malaysia. A total of 258 competitors (male = 66.7%, female = 33.3%), with a mean age of 18 years (SD = 2.6), volunteered to participate in this study. The original SCS with 50 items underwent forward and backward translations into the Malay language and was pre-tested with ten martial arts athletes. Then, Silat athletes were asked to complete the translated SCS-M questionnaire. There were five factors in the SCS-M (i.e., mastery, determination, assertiveness, venturesome, and self-sacrificial behaviour). The first hypothesised model with 50 items did not result in a good fit to the data (RMSEA = 0.06, CFI = 0.93, NFI = 0.87, NNFI = 0.93, RMR = 0.14, SRMR = 0.09). A total of 17 problematic items were identified and were removed iteratively. The final measurement model with 33 items fit the data well (RMSEA = 0.06, CFI = 0.94, NFI = 0.89, NNFI = 0.94, RMR = 0.05, SRMR = 0.07). The reliability of each subscale based on Cronbach's alpha ranged from 0.64 to 0.76. The convergent and discriminant validities were achieved for the final measurement model. The revised version of SCS-M with 33 items was considered valid and reliable for measuring the sports courage in Silat athletes in Malaysia.

Matched MeSH terms: Athletes
Fulltext Impacts of three different relaxation techniques on mood states among athletes

Hazliza Razali, Rohayah Husain, Marhasiyah Rahim, Nor Najibah Endut, Khairi Che Mat, Nordin Simbak, et al.

Malaysian Journal of Public Health Medicine, 2017;17(2):49-58.

Relaxation technique is a method, process, procedure or activity that helps a person to relax. There are several methods of relaxation techniques that can be used proven beneficial to improve the individual state of relaxation. Relaxation can be performed individually or in a group. With suitable technique of relaxation, it will improve quality of life as well as emotional and physical. This study aims to investigate the impact of three different relaxation techniques, namely Autogenic (AGR), Progressive Muscle (PMR) and Music Relaxation (MR) on mood states among Universiti Sultan Zainal Abidin (UniSZA) athletes. Eighty UniSZA athletes aged between 18 to 25 years old were randomly assigned into four groups which were AGR, PMR, MR and control group. Each groups consisted of 20 subjects which were male and female athletes with multidiscipline of the sports involvement. The mood states were determined by Brunel Mood Scale (BRUMS) during pre and post-intervention. The subjects in the three intervention groups received relaxation training twice a week for four weeks, 30 minutes per sessions. While, a control group not received any relaxation training during the intervention time. Repeated measure ANOVA conducted showed that the two parameters in BRUMS significantly changes in post-intervention such vigour (F=16.083, p<0.0001) and confusion (F=3.412, p=0.022). Other negative mood scores showed no significant changes such; (anger; F=2.235, p=0.091, depression; F=0.960, p=0.416, fatigue; F=0.724, p=0.540, tension; F=16.083, p=0.913).The results of Pairwise Comparison revealed that the three types of relaxation techniques (AGR, PMR and MR) effective to enhance vigour (positive mood) score among the adult subjects. In this study, PMR was the most effective relaxation technique followed by AGR and MR to regulate the mood state among adults.

Matched MeSH terms: Athletes
Measuring Vertical Jump Height With Artificial Intelligence Through a Cell Phone: A Validity and Reliability Report

Tan ECH, Weng Onn S, Montalvo S

J Strength Cond Res, 2024 Sep 01;38(9):e529-e533.
PMID: 38953840 DOI: 10.1519/JSC.0000000000004854

Erik, HT, Onn, SW, and Montalvo, S. Vertical jump height with artificial intelligence through a cell phone: a validity and reliability report. J Strength Cond Res 38(9): e529-e533, 2024-This study estimated the reliability and validity of an artificial intelligence (AI)-driven model in the My Jump 2 (My Jump Lab ) for estimating vertical jump height compared with the Force Platform (FP). The cross-sectional study involved 88 athletes (33 female and 55 male athletes), performing a total of 264 countermovement jumps with hands on hips. "Jump heights were simultaneously measured using the FP and the My Jump 2 app." The FP estimated jump heights using the impulse-momentum method, whereas My Jump 2 used the flight-time method, with the latter using an AI feature for automated detection of jump take-off and landing. Results indicated high reliability for the AI model (intraclass correlation coefficient [ICC 1,3 ] = 0.980, coefficient of variation [CV] = 4.12) and FP (ICC 1,3 = 0.990, CV = 2.92). Validity assessment showed strong agreement between the AI model and FP (ICC 2,k = 0.973). This was also supported by the Bland-Altman analysis, and the ordinary least products regression revealed no significant systematic or proportional bias. The AI-driven model in My Jump 2 is highly reliable and valid for estimating jump height. Strength and conditioning professionals may use the AI-based mobile app for accurate jump height measurements, offering a practical and efficient alternative to traditional methods.

Matched MeSH terms: Athletes
Monitoring recombinant human erythropoietin abuse among athletes

Citartan M, Gopinath SCB, Chen Y, Lakshmipriya T, Tang TH

Biosens Bioelectron, 2015 Jan 15;63:86-98.
PMID: 25058943 DOI: 10.1016/j.bios.2014.06.068

The illegal administration of recombinant human erythropoietin (rHuEPO) among athletes is largely preferred over blood doping to enhance stamina. The advent of recombinant DNA technology allowed the expression of EPO-encoding genes in several eukaryotic hosts to produce rHuEPO, and today these performance-enhancing drugs are readily available. As a mimetic of endogenous EPO (eEPO), rHuEPO augments the oxygen carrying capacity of blood. Thus, monitoring the illicit use of rHuEPO among athletes is crucial in ensuring an even playing field and maintaining the welfare of athletes. A number of rHuEPO detection methods currently exist, including measurement of hematologic parameters, gene-based detection methods, glycomics, use of peptide markers, electrophoresis, isoelectric focusing (IEF)-double immunoblotting, aptamer/antibody-based methods, and lateral flow tests. This review gleans these different strategies and highlights the leading molecular recognition elements that have potential roles in rHuEPO doping detection.

Matched MeSH terms: Athletes
Fulltext A machine learning approach of predicting high potential archers by means of physical fitness indicators

Muazu Musa R, P P Abdul Majeed A, Taha Z, Chang SW, Ab Nasir AF, Abdullah MR

PLoS One, 2019;14(1):e0209638.
PMID: 30605456 DOI: 10.1371/journal.pone.0209638

k-nearest neighbour (k-NN) has been shown to be an effective learning algorithm for classification and prediction. However, the application of k-NN for prediction and classification in specific sport is still in its infancy. The present study classified and predicted high and low potential archers from a set of physical fitness variables trained on a variation of k-NN algorithms and logistic regression. 50 youth archers with the mean age and standard deviation of (17.0 ± 0.56) years drawn from various archery programmes completed a one end archery shooting score test. Standard fitness measurements of the handgrip, vertical jump, standing broad jump, static balance, upper muscle strength and the core muscle strength were conducted. Multiple linear regression was utilised to ascertain the significant variables that affect the shooting score. It was demonstrated from the analysis that core muscle strength and vertical jump were statistically significant. Hierarchical agglomerative cluster analysis (HACA) was used to cluster the archers based on the significant variables identified. k-NN model variations, i.e., fine, medium, coarse, cosine, cubic and weighted functions as well as logistic regression, were trained based on the significant performance variables. The HACA clustered the archers into high potential archers (HPA) and low potential archers (LPA). The weighted k-NN outperformed all the tested models at itdemonstrated reasonably good classification on the evaluated indicators with an accuracy of 82.5 ± 4.75% for the prediction of the HPA and the LPA. Moreover, the performance of the classifiers was further investigated against fresh data, which also indicates the efficacy of the weighted k-NN model. These findings could be valuable to coaches and sports managers to recognise high potential archers from a combination of the selected few physical fitness performance indicators identified which would subsequently save cost, time and energy for a talent identification programme.

Matched MeSH terms: Athletes
Evaluation of Shoulder and Knee Isokinetic Strength Profile Among Elite Adolescent Badminton Players

Zulfikri N, Selvanayagam VS, Yusof A

J Sport Rehabil, 2021 Jan 19;30(5):717-724.
PMID: 33465761 DOI: 10.1123/jsr.2019-0483

CONTEXT: Badminton continues to be a highly competitive sport where training is introduced at an early age and load has intensiﬁed. This exposes players to a greater risk of injuries, in particular when assessing related training outcomes such as strength, agonist-antagonist ratio, and bilateral deﬁcit among adolescents where age- and sex-associated growth and development should be considered.
OBJECTIVE: To evaluate strength proﬁle of the upper and lower limbs among adolescent elite Malaysian badminton players.
DESIGN: Cross-sectional study.
SETTING: Laboratory.
PARTICIPANTS: Forty-eight asymptomatic athletes (24 males and 24 females) were grouped into early and late adolescence (13-14 y old and 15-17 y old, respectively).
MAIN OUTCOME MEASURE(S): Strength (absolute and normalized) of the external/internal rotators of the shoulder and ﬂexor/extensor of the knee and strength derivatives, conventional strength ratio (CSR), dynamic control ratio (DCR), and bilateral deﬁcits were measured.
RESULTS: Males showed greater strength in all strength indices (P < .05). The older group had greater strength compared to younger for most of the upper and lower limb indices (P < .05); these effects diminished when using normalized data. For females, there was no age group effect in the shoulder and knee strength. All players displayed lower shoulder and knee normative values for CSR and DCR. Dominant and non-dominant knee strength were comparable between sex and age groups.
CONCLUSIONS: For males, growth and maturation had a greater contribution to strength gained compared to training, whereas for females, growth, maturation, and training did not improve strength. The normalized data indicated that training did not improve all indices measured apart from external rotator strength in females. All players also displayed lower normative values of CSR and DCR. These results suggest that training in elite adolescent Malaysian badminton players lacks consideration of strength gain and injury risk factors.

Matched MeSH terms: Athletes
Assessment of Gait Symmetry Improvements in National Athletes after Anterior Cruciate Ligament Reconstruction during Rehabilitation

Hadizadeh M, Amri S, Roohi SA, Mohafez H

Int J Sports Med, 2016 Nov;37(12):997-1002.
PMID: 27551935

This study aimed to quantify changes in gait parameters and their symmetries among athletes with anterior cruciate ligament (ACL) reconstructions during a rehabilitation program. Twenty-two national players with ACL reconstructions and 15 healthy athletes were recruited. The gait data were collected between postoperative weeks 4-5, 8-9 and 12-13 using a three-dimensional motion analysis system. The spatio-temporal gait parameters and symmetry indexes (SIs) were evaluated for the patients and the control group. One-way and repeated-measures multivariate analysis of variance were used to analyse the data. The results demonstrated significant differences among spatio-temporal (P<0.001) and SIs (P=0.007) of patients for Test 1 and the control group. Repeated measure analysis revealed significant changes in the linear combinations of spatio-temporal gait variables (P=0.002) and SIs (P=0.043) over time. The injured limb's step length, cadence and weight acceptance time presented significant improvement across time (P<0.001). Moreover, the SI of the stance time was reduced significantly by 46.48% (P=0.004) among SI parameters. After three months, no significant differences were found between patients and healthy controls for the measured gait components (P>0.05). The rehabilitation program allowed national athletes to restore symmetry in spatio-temporal gait parameters toward the control group's range 12-13 weeks post-reconstruction.

Matched MeSH terms: Athletes

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links