Ekim Pekünlü

Acute effect of whole body vibration on isometric strength, squat jump, and flexibility in well-trained combat athletes

The purpose of this study was to investigate the effect of whole body vibration (WBV) training on maximal strength, squat jump, and flexibility of well-trained combat athletes. Twelve female and 8 male combat athletes (age: 22.8 ± 3.1 years, mass: 65.4 ± 10.7 kg, height: 168.8 ± 8.8 cm, training experience: 11.6 ± 4.7 years, training volume: 9.3 ± 2.8 hours/week) participated in this study. The study consisted of three sessions separated by 48 hours. The first session was conducted for familiarization. In the subsequent two sessions, participants performed WBV or sham intervention in a randomized, balanced order. During WBV intervention, four isometric exercises were performed (26 Hz, 4 mm). During the sham intervention, participants performed the same WBV intervention without vibration treatment (0 Hz, 0 mm). Hand grip, squat jump, trunk flexion, and isometric leg strength tests were performed after each intervention. The results of a two-factor (pre-post[2] × intervention[2]) repeated measures ANOVA revealed a significant interaction (p = 0.018) of pre-post × intervention only for the hand grip test, indicating a significant performance increase of moderate effect (net increase of 2.48%, d = 0.61) after WBV intervention. Squat jump, trunk flexion, and isometric leg strength performances were not affected by WBV. In conclusion, the WBV protocol used in this study potentiated hand grip performance, but did not enhance squat jump, trunk flexion, or isometric leg strength in well-trained combat athletes.

Relationship Between Fatigue Index and Number of Repetition Maxima with Sub-Maximal Loads in Biceps Curl

Abstract The aim of this study was to investigate the relationship between the number of repetition maxima to volitional failure (RM) at 60%, 75%, 90% of 1RM and fatigue index (FI), a determinant of the muscular endurance level. Thirty four resistance trained male participants attended two testing sessions. The first session was conducted to assess 1RM load and RM at 60%, 75% and 90% of 1RM in the supine biceps curl (SBC) exercise. In the second session, a FI test protocol consisting of five sets of SBC with 90 s rest between sets was performed to determine FI values. Each set was performed to volitional failure using a sub-maximal load in the range of 15-20RM. Hypothetical high FI and low FI groups (17 participants with the highest and lowest FI values, respectively) were formed for statistical analyses. ANOVA results revealed that RM at 60%, 75%, 90% of 1RM were not significantly different between FI groups when controlled for mean repetition tempo (p=0.11, p=0.38, p=0.13, respectively). Pearson’s correlation coefficients revealed that no significant relationship was present between FI values and RM at 60%, 75%, 90% of 1RM (p=0.40, p=0.46, p=0.14, respectively). In conclusion, the muscular endurance level of participants defined in terms of FI value was not an indicator of RM in SBC. Therefore, athletes with different muscular endurance levels can use similar percentages of 1RM in biceps curl exercise in their training programs when the aim is to elicit training adaptations related to specific RM zones.

Avoiding Systematic Errors in Isometric Squat-Related Studies without Pre-Familiarization by Using Sufficient Numbers of Trials

Abstract There is no scientific evidence in the literature indicating that maximal isometric strength measures can be assessed within 3 trials. We questioned whether the results of isometric squat-related studies in which maximal isometric squat strength (MISS) testing was performed using limited numbers of trials without pre-familiarization might have included systematic errors, especially those resulting from acute learning effects. Forty resistance-trained male participants performed 8 isometric squat trials without pre-familiarization. The highest measures in the first “n” trials (3 ≤ n ≤ 8) of these 8 squats were regarded as MISS obtained using 6 different MISS test methods featuring different numbers of trials (The Best of n Trials Method [BnT]). When B3T and B8T were paired with other methods, high reliability was found between the paired methods in terms of intraclass correlation coefficients (0.93-0.98) and coefficients of variation (3.4-7.0%). The Wilcoxon’s signed rank test indicated that MISS obtained using B3T and B8T were lower (p < 0.001) and higher (p < 0.001), respectively, than those obtained using other methods. The Bland- Altman method revealed a lack of agreement between any of the paired methods. Simulation studies illustrated that increasing the number of trials to 9-10 using a relatively large sample size (i.e., ≥ 24) could be an effective means of obtaining the actual MISS values of the participants. The common use of a limited number of trials in MISS tests without pre-familiarization appears to have no solid scientific base. Our findings suggest that the number of trials should be increased in commonly used MISS tests to avoid learning effect-related systematic errors

Drop in mechanical work: A highly reliable fatigue-related output in Wingate All-out Test

BACKGROUND: Mathematical procedures involved in the calculation of fatigue index (FI) and power drop (PD) are the main reasons why these traditional fatigue-related indices of Wingate All-out Test (WAT) are the least reliable indices. OBJECTIVE: To suggest a highly reliable fatigue-related output calculated by drop in mechanical work production (DMW). METHODS: Twenty-one well-trained male athletes (age: 21.8 ± 1.9 years, peak power [PP]: 14.7 ± 1.3 W · kg −1 ) participated in a series of WAT sessions, using 10% of their body mass as the workload, separated by 2–4 days. These WAT sessions were continued until the difference in PP between successive trials was less than 5%. Traditional FI and PD values were calculated using mean power data obtained from 5, 3, 2 and 1-second time intervals and using instantaneous power data, while DMW was calculated by predetermined areas in power-time curve. RESULTS: Intraclass correlation coefficients (ICC) and coefficient of variations (CV) revealed that DMW had higher reliability level (ICC = 0.92, CV = 4.53%) than that of traditional fatigue-related indices (ICC 0.91, CV 5.71%). In addition, DMW had the lowest limit of “real change” with 10.2% as the minimum detectable change score at 90% confidence. CONCLUSIONS: DMW might be used as a reliable output to evaluate fatigue-related power data of the anaerobic capability. Besides, Monark Inc. may easily modify its Peak Bike 894E software to make 30-second all-out test more reliable for the assessment of fatigability levels.

Uygun Olmayan İstatistiksel Analiz Kullanımı ve İstatistiksel Sonuçların Hatalı Yorumlanması

Araştırma tasarımlarında kontrol grubu kullanılmasının temel amacı, incelenen bağımlı değişken(ler)de zamana bağlı ortaya çıkabilecek olası değişim düzeyini belirlemektir. Bu şekilde “uygulama grubuna herhangi bir uygulama yapılmasaydı bu grupta da ilgili bağımlı değişkende bu düzeyde bir değişim gözlenecekti.” varsayımından yola çıkılarak, araştırmada kullanılan uygulamanın gerçek etkisinin belirlenmesi amaçlanmaktadır. Aras ve Akalan’ın araştırmasının hipotezlerini test etmek için gerçekleştirilmesi uygun olan istatistiksel analizleri şu şekilde sıralayabiliriz:

Randomization versus matching method in resistance training research: A simulation study based on maximal isometric squat strength recovery data

BACKGROUND: The randomization method (RM) is used as a gold standard for creating equal groups in most independentgroup design studies. OBJECTIVE: To identify whether the fatigue index (FI)-based matching method could be an alternative for the RM in the context of forming equal independent study groups using relative maximal isometric squat strength (R-MISS) recovery data as the dependent variable. METHODS: Baseline R-MISS values of 30 resistance-trained male participants were assessed. FI was calculated during an exhaustive training intervention (ETI), including four sets of submaximal isometric squat contractions. Maximal isometric squats were performed 30 seconds, and 2, 4, 6, 8, 10, 12, and 14 minutes after the ETI to assess the recovery levels of R-MISS. For the statistical analyses, lowand high-endurance groups, and two equal-endurance groups (each including 15 participants) were retrospectively formed based on FI scores. RESULTS:The results of the repeated-measures analysis of variance revealed that recovery moments greatly differed (8 minutes) between the highand low-endurance groups but were similar between the two equal-endurance groups (difference of 2 minutes). Simulations performed using the resampling procedure revealed that the FI-based matching method was more successful than the RM (71.6% vs. 56.2%) in the context of forming equal study groups. CONCLUSIONS: These results indicate that the FI-based matching method is a better alternative to the RM for preventing an unequal distribution of participants among independent groups in R-MISS recovery-related studies.