by Damjana V. Cabarkapa, Dimitrije Cabarkapa and Andrew C. Fry
Original Research
Quantifying training loads as the amount of stress that athletes are exposed to during a practice session and/or game has received increased attention in recent years. The inertial measurement unit (IMU) has become one of the most commonly implemented technologies for monitoring external loads in volleyball. Thus, the purpose of the present study was to examine differences in the external load variables obtained via VertTM IMU between different playing positions (e.g., setter, middle blocker, outside, and opposite hitter) in professional male volleyball players. Eighteen athletes competing in one of the top European volleyball leagues volunteered to participate in the present study. The average of the following external load variables was obtained across three practice sessions: Stress, Jumps, Jumps 15+, Jumps 20+, Highest Jump, and Average Jump Height. The results of the present study indicated that outside hitters had a significantly greater number of Jumps 20+ as well as a greater Highest Jump when compared to the setters, while opposite hitters had significantly greater Highest Jump than both setters and middle blockers. In addition, setters demonstrated lower Average Jump Height when compared to the outsides and opposites. These findings may help strength and conditioning practitioners and volleyball coaches to develop position-specific training regimens and eventually decrease the likelihood of overuse injuries.
American Journal of Sports Science and Medicine. 2022, 10(1), 25-28. DOI: 10.12691/ajssm-10-1-5
Pub. Date: October 24, 2022
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by Ratko Pavlović, Vladan Savić, Danilo Tadić and Ljubo Milićević
Original Research
Background: Morphological dimensions represent the functioning of the growth and development of the musculoskeletal system and also play a role in specific volleyball activities. In the sphere of volleyball, it is imperative to identify the anthropometric constitution, generated by exogenous and endogenous factors. Aim study: The main goal of the research was to determine the factor structure of isolated latent dimensions of the population of female volleyball players of VC "Jahorina" Pale, a member of the volleyball Premier League of Bosnia and Herzegovina. Methods: The study involved 18 active players of the women's volleyball club Jahorina (BH=173±8.77cm; BW=66.04±9.09kg; BMI=22.03±2.19kg/m2, age=19.11±2.63 years old) members of the volleyball Premier League of Bosnia and Herzegovina. A set of 15 anthropometric variables was measured in the morphological space with the aim of determining correlations between anthropometric characteristics and identifying the latent morphological structure of volleyball players. Result: Statistical processing of the data was performed by Pearson correlation coefficients and Hoteling principal components analysis (PCA). The results of the correlation analysis showed statistically significant linear correlations between most anthropometric variables (p<0.05; p<0.01; p<0.001). The three-component model, which defined 81.45% of the proportion of the total common variance of the manifest anthropometric variables, was extracted by the method of analysis of the main components, with the Gutman-Kaiser criterion and Varimax rotation. Conclusion: It was structured by hypothetical factors with characteristic roots (Eig.>1), which were interpreted as Factor of volume and longitudinal dimensionality of the skeleton (F1=42.45%; Eig. 6.37>1), Factor of skin folds of the trunk (F2=28. 96; Eig. 4.08>1) and Subcutaneous adipose tissue factor of the lower extremities (F3=10.04; Eig.2.12>1). The correlation of the factors confirmed the inverse relationship of the factors (F1-F2=-0.85; F1-F3=-0.81). It can be concluded that the increased volume of volleyball players is not accompanied by higher values of skin folds, but is a consequence of increased muscle mass.
American Journal of Sports Science and Medicine. 2022, 10(1), 17-24. DOI: 10.12691/ajssm-10-1-4
Pub. Date: September 08, 2022
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by Andreas G. Bourantanis, Nikitas N. Nomikos, Constantinos C. Trompoukis and Weijie W. Wang
Original Research
Combat sports pose a discrete thesis in terms of biomechanics among the majority of the sport activities. This research aims to identify and study the position of Centre of Mass (CoM) in ancient Greek Athletes who participated in combat sports, especially in Pankration. This project was carried out by analyzing figures drawn on ancient pottery. The study calculated the CoM using innovative software and programming: OpenPose, Sublime text, Python programming language, and Matplotlib library. According to the results, the study succeeded (for the first time globally) in calculating the CoM of ancient Pankratiasts during the contests.
American Journal of Sports Science and Medicine. 2022, 10(1), 12-16. DOI: 10.12691/ajssm-10-1-3
Pub. Date: July 13, 2022
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by Andrew C. Fry, Justin X. Nicoll, Dimitrije Cabarkapa and Paige N. Stephens
Original Research
This study examined acute hormonal responses to multi-joint free weight exercise and single joint machine exercise. Six weight-trained males performed 3 sets of 10 repetitions at 70% of 1RM with one minute rest between each set on either the barbell squat (FW) or three single joint machine weight exercises (MW; i.e., leg curl, leg extension, back extension) using similar primary movers in a randomly-ordered crossover design. Testosterone (T), cortisol (C), growth hormone (GH), and lactate (HLa) were determined from blood samples 15 minutes before (PRE) and 5 minutes after (POST) each exercise session performed at the same time of day. The MW group completed significantly more estimated external work than the FW group (J; MW = 30776±2152, FW = 19728±2399), but the FW protocol resulted in a greater HLa response (mmol.L-1; MW, PRE = 1.2±0.1, POST = 6.7±0.7; FW, PRE = 1.5±0.1, POST = 10.5±1.6). Both exercise modalities exhibited similar increases in T (nmol.L-1; MW, PRE = 13.4±2.7, POST = 17.6±2.9; FW, PRE = 15.5±2.8, POST = 17.6±3.5) and GH (g.L-1; MW, PRE = 1.4±0.3, POST = 6.8±3.3; FW, PRE = 1.1±0.1, POST = 4.3±2.0), despite the lower work performed by the FW protocol. Although C increased for both protocols, the FW session induced a greater C response (nmol.L-1; MW, PRE = 463.2±147.8, POST = 448.1±144.1; FW, PRE = 444.4±174.0, POST = 696.9±220.4). While using similar muscle mass, these results suggest that the acute hormonal response is partially dependent on exercise modality. Despite completing less estimated external work, FW exercise protocol yielded similar or greater endocrine responses when compared to MW resistance training modality.
American Journal of Sports Science and Medicine. 2022, 10(1), 6-11. DOI: 10.12691/ajssm-10-1-2
Pub. Date: June 01, 2022
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by Yoshinori Nagasawa, Shin-ichi Demura and Hiroshi Hirai
Original Research
Center of gravity shaking (CGS) changes constantly during a standing posture and its variation increases depending on the disturbance stimulus. One-side-shoulder bag (OSB) holding with a heavy weight makes the standing posture unstable because it imposes burden on one side of the shoulder and/or lower back. It is assumed that the effect of OSB on CGS differs by bag weight and the habitual and non-habitual use of one shoulder. This study aimed to examine the effect of different weights and holding shoulders on CGS during OSB in a standing posture in 30 healthy young women aged 21-24 years. The experimental conditions were relative weight loads (0% [non-bag holding], 5%, 10%, and 15% of body mass [BM]) and bag holding shoulder (habitual and non-habitual). The participants maintained a Romberg posture (standing posture with feet closed) with eyes open for 1 minute on the measurement equipment in the above-mentioned eight conditions. The x-axis, y-axis, and total trajectory lengths and outer peripheral area were transmitted to a computer at a sampling rate of 20 Hz. The measurement order was randomized for the different weight loads and holding shoulders. Two measurements were obtained for each condition with a 1-min rest between measurements. The two measurements were then averaged. A two-way analysis of variance (ANOVA) showed that the x-axis, y-axis, and total trajectory lengths were significantly higher for weight loads of 10% BM and above. The outer peripheral area value was significantly lower for the habitual holding shoulder. The 10% and 15% BM weights had significantly higher outer peripheral area values compared with the 0% BM weight, and the 15% BM weight had significantly higher outer peripheral area values compared with the 5% and 10% BM weights. The x-axis, y-axis, and total trajectory lengths and outer peripheral area become greater as bag weight increases over 10% BM. OSB holding leads to a larger outer peripheral area in the non-habitual holding shoulder compared with the habitual holding shoulder in young women.
American Journal of Sports Science and Medicine. 2022, 10(1), 1-5. DOI: 10.12691/ajssm-10-1-1
Pub. Date: May 17, 2022
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